Body-conformable absorbent article

Abstract

An absorbent article having a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent structure comprising an open-cell absorbent foam material disposed between the topsheet and the backsheet. The absorbent article has been incrementally stretched in at least a first stretching direction and a second stretching direction such that the topsheet and the backsheet each comprise a plastically stretched zone, the plastically stretched zones are disposed substantially along a first plurality of deformation lines substantially perpendicular to the first stretching direction and a second plurality of deformation lines substantially perpendicular to the second stretching direction. The absorbent foam material breaks substantially along the first plurality of deformation lines and the second plurality of deformation lines into a plurality of discrete foam sheets separated from adjacent sheets by gaps. An adhesive is positioned between the topsheet and the discrete foam sheets and bonds the discrete foam sheets to the topsheet.

Description

Technical Field

[0001] The present disclosure relates to a body-conformable absorbent article and a method of manufacturing such absorbent articles. Background Art

[0002] For many years, women have used absorbent articles such as feminine hygiene pads (also known as sanitary napkins) to intercept, contain, absorb, and retain the discharged menstrual fluid and avoid soiling underwear, outerwear, bedding, etc. during menstruation.

[0003] To perform its intended function well, ideally, a feminine hygiene pad should:

[0004] • Conform closely to the body of the wearer to intercept the discharged fluid moving along the skin surface and prevent it from escaping from the pad;

[0005] • Readily receive and wick the discharged fluid;

[0006] • Absorb the fluid easily;

[0007] • Have an absorption capacity and associated discharge volume during the wearing duration sufficient to provide reasonable convenience to the wearer / user;

[0008] • Resist allowing the absorbed fluid to wick back to the surface facing the wearer (which can result in an undesirable wet feeling against the wearer's skin);

[0009] • Resist allowing the absorbed fluid to be extruded from the pad under the pressure exerted on the pad during, for example, body movement, sitting, etc.; and

[0010] • Remain reliably positioned properly within the wearer's underwear during the wearing duration while accommodating the stretching and movement of the underwear fabric as the wearer's body moves.

[0011] In addition, many users prefer the pad to be relatively small and / or thin (relatively low surface area and / or low volume / thickness) in some situations so as to be discreet when worn with a tight fit and / or showing through outerwear. Users generally also prefer the pad to be comfortable to wear, i.e., feel soft, compliant, and / or "breathable", i.e., steam permeable (to allow water vapor to escape and prevent the pad from feeling uncomfortably warm and / or prevent excessive hydration of the area of the wearer's skin under the pad during wearing).

[0012] It should be understood that it is difficult to design a feminine hygiene pad having a combination of component materials and configurations that fully meet all of these objectives, as they are somewhat conflicting. For example, sufficient absorbency typically requires a minimum volume and / or amount of absorbent material, which may come at the expense of small size, low volume / thickness, and flexibility or conformability. As another example, absorbent materials currently used in many feminine hygiene pads, including combinations containing cellulose fibers, are effective for the purposes of fluid wicking and absorbency, but do not contribute to (and in many cases impede) the configuration of a particularly flexible, compliant, or body-conformable pad.

[0013] Accordingly, there is still room for improvement in the combination of component materials and configurations of feminine hygiene pads that more effectively meet more of the objectives identified above. SUMMARY OF THE INVENTION

[0014] An absorbent article is described herein that includes a longitudinal axis and a lateral axis; a liquid-permeable topsheet having a garment-facing surface and an opposing wearer-facing surface; a liquid-impermeable backsheet having a garment-facing surface and an opposing wearer-facing surface; and an absorbent structure including an open-cell absorbent foam material disposed between the topsheet and the backsheet. The absorbent article has been incrementally stretched along at least a first stretch direction and a second stretch direction different from the first stretch direction such that the topsheet and the backsheet each include plastically stretched regions that are disposed substantially along a first plurality of deformation lines that are substantially perpendicular to the first stretch direction and a second plurality of deformation lines that are substantially perpendicular to the second stretch direction. The absorbent foam material is broken into a plurality of discrete foam sheets substantially along the first plurality of deformation lines and the second plurality of deformation lines, wherein the discrete foam sheets are separated from adjacent sheets by gaps. An adhesive of from about 15 gsm to about 35 gsm is positioned between the garment-facing surface of the topsheet and the wearer-facing surface of the discrete foam sheets and bonds the discrete foam sheets to the topsheet.

[0015] The present document also describes an absorbent article that includes a longitudinal axis and a lateral axis; a liquid-permeable topsheet having a clothing-facing surface and an opposite wearer-facing surface; a liquid-impermeable backsheet having a clothing-facing surface and an opposite wearer-facing surface; and an absorbent structure that includes an open-cell absorbent foam material disposed between the topsheet and the backsheet. The topsheet and the backsheet each include plastically stretchable regions that are disposed substantially along a first plurality of deformation lines extending in a first direction and a second plurality of deformation lines extending in a second direction. The first plurality of deformation lines form an angle α with respect to the longitudinal axis, and the second plurality of deformation lines form an angle β with respect to the longitudinal axis, where each of the angle α and the angle β is from about 5 degrees to 85 degrees. The absorbent structure includes a plurality of discrete foam sheets arranged along the deformation lines, where the discrete foam sheets are separated from adjacent sheets by a gap of 0.3 mm to 1.2 mm.

[0016] The present document also describes an absorbent article that includes a longitudinal axis and a lateral axis; a liquid-permeable topsheet; a liquid-impermeable backsheet having a basis weight of from about 20 gsm to about 28 gsm; and an absorbent structure that includes a high internal phase emulsion foam disposed between the topsheet and the backsheet. The topsheet and the backsheet each include plastically stretchable regions, where a portion of the plastically stretchable regions extends continuously from a first side of the topsheet to a second side of the topsheet. The absorbent structure includes a plurality of discrete foam sheets arranged in a pattern that extends across the entire absorbent structure, where the discrete foam sheets are spaced apart from adjacent sheets by a gap greater than 0.1 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A plan view of an example of an absorbent article in the form of a feminine hygiene pad, with the wearer-facing side up, showing an example of a two-way deformation pattern.

[0018] Figure 2 A plan view of an example of an absorbent article in the form of a feminine hygiene pad, with the wearer-facing side up, showing various other features.

[0019] Figures 3A to 3C A schematic plan view of several possible non-limiting examples of the pattern of the bonding area between the topsheet of the absorbent article and the underlying components.

[0020] Figure 3D A schematic plan view of another possible example of the adhesive deposition pattern for forming a bonding area between the topsheet of the absorbent structure and the underlying components.

[0021] Figure 4A For Figure 1 taken along line 4A-4A inFigure 1 Schematic side cross-section of the article shown.

[0022] Figure 4B In one possible example, Figure 4A The part marked by circle 4B in Figure 4A Enlarged view.

[0023] Figure 4C In another possible example, Figure 4A The part marked by circle 4B in Figure 4A Enlarged view.

[0024] Figure 4D In another possible example, Figure 4A The part marked by circle 4B in Figure 4A Enlarged view.

[0025] Figure 5 Plan view of another example of an absorbent article in the form of a feminine hygiene pad, with the wearer-facing side up, showing another example of a biaxial deformation pattern.

[0026] Figure 6 Enlarged view of arrows indicating the direction of the stretching and deformation lines along the x-y plane, the relative longitudinal and lateral axes of the absorbent structure.

[0027] Figure 7 Plan view of another example of an absorbent article in the form of a feminine hygiene pad, with the wearer-facing side up, showing specific features.

[0028] Figure 8 Simplified schematic side view of the components of a process arranged to deform a composite fiber web.

[0029] Figure 9 Perspective view of an example of a pair of deformation rollers.

[0030] Figure 10 View of the engagement features of a part of an example of a pair of deformation rollers.

[0031] Figure 11 Is Figure 10 A closer view of the features shown in

[0032] Figure 12 Schematic cross-sectional view (along the z-direction plane) of an example of a deformed fiber web.

[0033] Figure 13 View along the machine direction of another example of a pair of deformation rollers.

[0034] Figure 14Is a machine direction view of another example of a pair of pattern rolls.

[0035] Figure 15A Is a machine direction view of another example of a pair of pattern rolls.

[0036] Figure 15B Is a machine direction view of another example of a pair of pattern rolls.

[0037] Figure 16A Is a machine direction view of another example of a pair of pattern rolls.

[0038] Figure 16B Is a machine direction view of another example of a pair of pattern rolls.

[0039] Figure 17 Is a schematic diagram of the equipment used in the conformable force measurement method described herein.

[0040] Figure 18 Is a schematic diagram of the equipment used in the capillary work potential via the pore volume distribution method described herein.

[0041] Figure 19 Is a reproduction of a photograph of an absorbent article in the form of a feminine sanitary pad, with the wearer side facing up, which gives an example of a biaxial deformation pattern.

[0042] Figure 20 Is Figure 19 Is a reproduction of a portion of a side cross-sectional cut photograph of the absorbent article shown, shown adjacent to a scale with centimeter / millimeter markings.

[0043] Figure 21A Is an enlarged schematic cross-section of a portion of an absorbent article including two adjacent sheets of an absorbent structure shown in a flat configuration along a plane in the z-direction.

[0044] Figure 21B Is an enlarged schematic cross-section of a portion of an absorbent article including two adjacent sheets of an absorbent structure shown in a curved configuration along a plane in the z-direction.

[0045] Figure 22A Is an enlarged schematic cross-section of a portion of an absorbent article including two adjacent sheets of an absorbent structure shown in a flat configuration along a plane in the z-direction.

[0046] Figure 22B Is an enlarged schematic cross-section of a portion of an absorbent article including two adjacent sheets of an absorbent structure shown in a curved configuration along a plane in the z-direction.

[0047] Figure 23It is a cross-sectional view of a line contact gripper for high-speed tensile testing in this article.

[0048] Figure 24 It is a perspective view of a pair of opposing line contact grippers for high-speed tensile testing in this article.

[0049] Figure 25 It is a graphical illustration of a suitable deformation scheme for high-speed tensile testing in this article. Detailed implementation

[0050] Definition

[0051] For the purposes of this article, the following terms will have the meanings set forth:

[0052] "Absorbent article" means a layered product that includes an absorbent structure and is configured to be worn around the exterior of a person's lower body and / or crotch area and is configured to contain and / or absorb body exudates, which may include urine, menstrual fluid, or feces. Examples of absorbent articles include feminine hygiene pads (also known as menstrual pads or sanitary napkins), pantiliners, menstrual underwear, incontinence pads, absorbent underwear (configured for example to manage incontinence), and diapers and training pants.

[0053] "Biaxial" - with respect to a layered composite fibrous web structure or any of its layer components, refers to the directions of two axes that intersect at a smaller angle within the range of 20 degrees to 90 degrees in the x-y plane.

[0054] A fibrous web, sheet, or film material, or a laminate or composite thereof, is considered "extensible" for the purposes of this article if a tensile force of no greater than 50 gf / mm (gf / mm sample width, where the width is measured perpendicular to the tensile direction) is applied to the material in question along the tensile direction, and the material can extend along that direction to an elongation dimension that is at least 110% of its original relaxed dimension (i.e., it can extend by at least 10% of its original relaxed dimension) without significant breakage (fracture, breakage) of the fibrous web, sheet, or film material or its laminate or composite in question. For the purposes of this article, plastic deformation is not considered significant damage.

[0055] For the purposes of this document, a web, sheet or film material, or a laminate or composite thereof, is "elastic" or "elastically extensible" for the purposes of this document if, when a tensile force not greater than 50 gf / mm (gf / mm of the sample width, where the width is measured perpendicular to the direction of stretch) is applied to the material in question along the direction of stretch, the material can be extended along that direction to an extended dimension that is at least 110% of its original relaxed dimension (it can extend by at least 10% of its original relaxed dimension) without significant damage such as rupture or breakage of the web, sheet or film material in question or its laminate or composite. And when the force is removed from the material in question, the material contracts along the direction of stretch to recover at least 40% of such extension. For example, if a piece of fabric having an original relaxed length of 100 mm and a width of 40 mm can be extended to a length of 110 mm in the direction along its length by a tensile force of 2000 gf (50 gf / mm) without significant damage and will contract to a length not greater than 106 mm (110 mm - 106 mm = 4 mm = 40% of 10 mm) when the force is removed, then it is "elastic" as defined herein. The "elongation rate" used herein to quantify and represent the strain applied to an elastic material in the direction of stretch means: {[(the strained length of the strand) – (the length of the strand before strain)] / (the length of the strand before strain)} × 100%.

[0056] "Joined" includes configurations by which an element can be directly fixed to another element by directly connecting one element to the other; it also includes configurations by which an element can be indirectly fixed to another element by connecting one element to an intermediate member and then connecting the intermediate member to other elements.

[0057] "Lateral" - with respect to an absorbent article or a component thereof, means the direction parallel to a horizontal line tangent to the front surface of the upper portion of the wearer's leg adjacent to the torso when the article is worn normally and the wearer has assumed a uniform, square, normal standing posture. The "width" dimension of any component or feature of the absorbent article is measured along the lateral direction. When the absorbent article or a component thereof is placed flat on a horizontal surface, the "lateral" direction corresponds to the lateral direction with respect to the structure when it is worn, as defined above. With respect to an absorbent article opened and lying flat on a horizontal flat plane, "lateral" means the direction perpendicular to the longitudinal direction and parallel to the horizontal flat plane.

[0058] The "lateral axis" of an absorbent article or a component thereof is a lateral line located in the x - y plane and, when the absorbent article or a component thereof is opened and lying flat on a horizontal surface, this lateral line bisects the length of the article or component. The lateral axis is perpendicular to the longitudinal axis.

[0059] "Longitudinal" - with respect to an absorbent article or a component thereof, refers to a direction perpendicular to the lateral direction. The "length" dimension of any component or feature of a layered absorbent structure is measured along the longitudinal direction from its forward extent to its rearward extent. When the absorbent article or a component thereof is laid flat on a horizontal surface, the "longitudinal" direction is perpendicular to the lateral direction with respect to the structure when it is being worn, as defined above.

[0060] The "longitudinal axis" of an absorbent article or a component thereof is a longitudinal line lying in the x-y plane, and when the article is opened and laid flat on a horizontal surface, this longitudinal line bisects the width of the article. The longitudinal axis is perpendicular to the lateral axis.

[0061] "Liquid-impermeable" - refers to one or more properties or characteristics of a film, a nonwoven material, or a laminate thereof, which, under the ordinary use conditions of an absorbent article, cause it to resist the passage of aqueous liquids therethrough (from one major surface to the other opposing major surface). A film, a nonwoven material, or a laminate thereof may be liquid-impermeable but may also be vapor-permeable ("breathable").

[0062] "Machine direction" - with respect to the process for manufacturing a nonwoven material or a laminate or a layered arrangement of nonwoven materials, refers to the main direction in which the material is conveyed along a production line when viewed from above the production line. It should be understood that the machine direction may change in the absolute direction orientation in space at a particular location along the production line if the production line is so configured. With respect to the nip between a single roll or a pair of rolls, on or in which a nonwoven material or a combination of nonwoven materials is conveyed, laminated, or deformed on the production line, the "machine direction" is generally perpendicular to the axis of the roll, and the "cross-machine direction" is generally parallel to the axis of the roll.

[0063] "Permanent mechanical deformation" - means plastic deformation, fracture (fractured, broken), or having individual fiber components that have been plastically deformed, fractured (fractured, broken), and / or directionally rearranged or reoriented by the application of mechanical force.

[0064] The "x-y plane" with respect to an absorbent article or a component thereof means any horizontal plane occupied by the horizontal surface or any layer of the article or component when laid flat on a horizontal surface.

[0065] The "z-direction" with respect to an absorbent article or a component thereof is the direction orthogonal to the x-y plane when laid flat on a horizontal surface. When the article is being worn by a user (and thus has been pushed into a curved configuration), the "z-direction" at any particular point location on the pad refers to the direction perpendicular to the surface of the pad facing the wearer at the particular point location.

[0066] With respect to an absorbent article or its components, the terms "front", "rear", "forward", and "backward" and similar relative position terms relate to a feature or region of the pad that corresponds to the position that would be occupied by the user when normally worn, relative to the front (anterior) and back (posterior) of the wearer / user's body when standing.

[0067] With respect to an absorbent article, "toward the wearer" is a relative position term that refers to a feature of a component or structure of the article that, when in use, is closer to the wearer than another feature of a component or structure placed along the same z-direction line. For example, the topsheet has a surface that is toward the wearer and that is closer to the wearer than the opposite, outward-facing surface of the topsheet.

[0068] With respect to an absorbent article, "outward-facing" (sometimes referred to herein as "toward the clothing") is a relative position term that refers to a feature of a component or structure of the article that, when in use, is farther from the wearer than another feature of a component or structure placed along the same z-direction line. For example, the topsheet has an outward-facing surface that is farther from the wearer than the opposite, wearer-facing surface of the topsheet.

[0069] The terms "top", "bottom", "upper", "lower", "above", "below", "beneath", "adjacent above", "adjacent below", and similar vertical position terms, when used herein to refer to a layer, component, or other feature of a wearable absorbent article, are to be interpreted relative to the article as it would appear when opened out and laid flat on a horizontal surface, with its wearer-facing surface facing up and its outward-facing surface facing down. Detailed Description

[0070] This disclosure relates to absorbent articles, and more particularly, to absorbent articles having improved flexibility and conformability. In some configurations, an absorbent article can include a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent structure disposed between the topsheet and the backsheet. The absorbent structure, together with one or both of the topsheet and the backsheet, can be incrementally stretched, resulting in permanent deformation of the topsheet and / or the backsheet and fracture of the absorbent structure into discrete sheets. Surprisingly, it has been found that when an absorbent article having non-orthogonal biaxial deformation adheres to the inside of the wearer's undergarment, it is more likely to shift and conform to the body movements of the wearer (e.g., walking). The absorbent articles described herein can bend, flex, and stretch with the wearer's undergarment, allowing the article to remain in close contact with the body as she moves and providing a more comfortable experience for the wearer while still keeping the discrete sheets of the absorbent structure in place.

[0071] See Figure 1 and Figure 4A, the absorbent article 10 (shown herein in the form of a feminine sanitary pad) may include a liquid-permeable topsheet 20, a liquid-impermeable backsheet 30, and an absorbent structure 40 disposed between the topsheet and the backsheet. The absorbent structure has an outer periphery 40a. In the region outside the outer periphery 40a, the topsheet and the backsheet may be bonded together in a laminated configuration by any suitable mechanism including, but not limited to, adhesive bonding, thermal bonding, pressure bonding, etc., thereby holding and securing the absorbent structure 40 in the encapsulated space between the topsheet 20 and the backsheet 30. The article 10 may include opposing wings 15 that extend laterally outside the periphery 40a and have a relatively greater width dimension than the width dimensions of the frontmost and rearmost portions of the pad. The outer surface of the backsheet forming the underside of the main body and the wings 15 may have a deposit of adhesive 35 thereon. The adhesive deposit 35 may be provided so that the user can adhere the pad to the inner side of her underwear in the crotch region, wrap the wings 15 through and around the inner edge of the leg opening of the underwear, and adhere them to the outer / lower side of the underwear in the crotch region, thereby providing supplementary holding support and helping to protect the inner side of the leg edge of the underwear from soiling. When the article 10 is encapsulated, the adhesive deposit 35 may be covered by one or more sheets of release film or paper (not shown) that covers / protects the adhesive deposit 35 from contact with other surfaces until the user is ready to remove the release film or paper and place the pad in her underwear for wearing / use.

[0072] Top sheet

[0073] The topsheet 20 may be formed of any suitable nonwoven web material having plastic / non-elastic extensibility suitable for the purposes described herein. Referring back to the drawings, the topsheet 20 is positioned adjacent to the wearer-facing surface of the absorbent structure 40 and may be joined thereto and to the backsheet 30 by any suitable attachment or bonding method. The topsheet 20 and the backsheet 30 may be joined directly to each other in the outer peripheral region outside the periphery 40a of the absorbent structure 40 and may be joined indirectly by joining them respectively directly to the wearer-facing surface and the outward-facing surface of the absorbent structure.

[0074] The article 10 may have any known topsheet 20 that is otherwise effective, such as a topsheet that is compliant, feels soft, and is non-irritating to the wearer's skin. Suitable topsheet materials will include liquid-permeable materials that are comfortable when in contact with the wearer's skin and allow the discharged menstrual fluid to rapidly penetrate therethrough. Suitable topsheets may be made of a variety of materials, such as woven and knitted materials, nonwoven web materials, or perforated films.

[0075] Non-limiting examples of nonwoven web materials suitable for use as topsheet 20 include fibrous materials made from natural fibers, modified natural fibers, synthetic fibers, or combinations thereof. Some suitable examples are described in U.S. Patent Nos. 4,950,264, 4,988,344, 4,988,345, 3,978,185, 7,785,690, 7,838,099, 5,792,404, and 5,665,452. Particularly suitable topsheet materials can include spunbond nonwoven materials comprising polyethylene (PE) / polypropylene (PP) bicomponent fibers (PE skin and PP core).

[0076] In some configurations, the topsheet can be a highly extensible nonwoven fibrous web comprising short fibers or continuous multicomponent fibers, such as, for example, those described in US 2020 / 0337910A1. The highly extensible nonwoven fibrous web can beneficially reduce fiber breakage under mechanical processing that can cause the nonwoven fibrous web to experience high strain forces, such as during an incremental stretching process. In the context of an absorbent article, this can have the desired effect of reducing the amount of broken fibers that adhere to the wearer's skin. In some configurations, the topsheet can include a first polymer component having a first melting temperature and a second polymer component having a second melting temperature. For example, the first polymer component can have a low crystallinity between about 10% and about 41%, between about 15% and about 38%, between about 20% and about 35%, between about 25% and about 33%, or between about 28% and about 30%, specifically listing the specified ranges and all 0.1% increments within or formed therefrom. Crystallinity can be measured in fibers or nonwoven fibrous webs containing fibers according to the crystallinity tests disclosed herein. For example, the first polymer component can have a melting temperature between about 130°C and about 161°C, between about 130°C and about 155°C, or between about 135°C and about 155°C, specifically listing the specified ranges and all 0.1°C increments within or formed therefrom. Without being bound by theory, it is believed that a polymer with low crystallinity can increase the ductility of fibers by increasing the ultimate tensile strength of the fibers. In one example, polypropylene with a crystallinity between about 20% and about 41% can be the first polymer of a multicomponent fibrous nonwoven web. In another example, polyethylene terephthalate with a crystallinity between about 20% and about 41% can be the first polymer of a multicomponent fibrous nonwoven web. For example, the second polymer component can have a high crystallinity between about 40% and about 80%, between about 45% and about 75%, between about 50% and about 70%, or between about 55% and about 65%, specifically listing the specified ranges and all 0.1% increments within or formed therefrom. Without being bound by theory, it is believed that a polymer with high crystallinity can increase the tensile strength of the fibers and the tensile strength of the nonwoven fibrous web containing such fibers. The second polymer component can optionally have the same or a lower melting temperature than the first polymer component. In one example, polyethylene can be the second polymer component of a multicomponent continuous fiber.

[0077] In the context of a nonwoven fibrous web comprising continuous bicomponent fibers, the first polymer component may be or may comprise polypropylene having a crystallinity between about 20% and about 41%. The polypropylene may have a melting temperature between about 130 °C and 161 °C. The second polymer component may be or may comprise polyethylene having a crystallinity between about 45% and about 75%. The polyethylene may have a crystallization rate between about 1300 ms and about 1360 ms. The polyethylene may have a melting temperature between about 100 °C and about 140 °C. The bicomponent fibers may have a core / sheath configuration, where the polypropylene forms the core of the fiber and where the polyethylene forms the sheath, partially or completely surrounding the polypropylene core. Without being bound by theory, it is believed that the low crystallinity polypropylene fiber core can be used to produce a nonwoven fibrous web having improved tensile properties, including increased ductility. Additionally, it is believed that the skin material having high crystallinity and fast crystallization time partially or completely surrounding the core material during fiber spinning can protect the core material and result in a more amorphous structure in the finished fiber.

[0078] In another example, the first polymer component of the bicomponent continuous fiber may be polyethylene terephthalate (PET) having a crystallinity between about 20% and about 41%. The second polymer component may be polyethylene. The continuous fiber may comprise a core / sheath structure, where the PET may form the core of the fiber and the polyethylene may partially or completely surround the PET and form the sheath of the fiber.

[0079] In some configurations, the topsheet may comprise a highly extensible nonwoven fibrous web having an extensibility between about 300% and about 500%, between about 305% and about 450%, between about 310% and about 425%, between about 315% and about 400%, or between about 320% and about 375%, specifically listing the specified ranges according to high speed tensile testing and all 1% increments within all ranges formed therein or therefrom. The highly extensible nonwoven fibrous web having an extensibility within the above ranges can beneficially reduce fiber breakage under mechanical processing, which can cause the nonwoven fibrous web to experience high strain forces. Reduced fiber breakage can result in a stronger nonwoven fibrous web with reduced lint.

[0080] In some configurations, the topsheet 20 may comprise a plurality of holes. In some configurations, it may be preferred to have a topsheet that does not include holes to help prevent the foam sheet from escaping from the article during use.

[0081] In some configurations, the topsheet 20 may have a basis weight of about 10 gsm (herein, "gsm" means grams / m 2 ) to about 50 gsm, about 22 gsm to about 45 gsm, or about 25 gsm to about 30 gsm, specifically listing these ranges and all values within any resulting ranges.

[0082] In some configurations, topsheet 20 may include clusters, as described in US 8,728,049, US 7,553,532, US 7,172,801, US 8,440,286, US 7,648,752, and US 7,410,683. Topsheet 20 may have a pattern of discrete hair-like fibrils as described in US 7,655,176 or US 7,402,723. Additional examples of suitable topsheet materials include those described in US 8,614,365; US 8,704,036; US 6,025,535, and US 2015 / 041640. Another suitable topsheet may be formed from a three-dimensional substrate, as described in detail in US 2017 / 0258647. The topsheet may have one or more layers, as described in US 2016 / 0167334; US 2016 / 0166443, and US 2017 / 0258651.

[0083] As contemplated herein, the component nonwoven web material from which topsheet 20 may be cut may be a nonwoven web material comprising cellulose plant fibers or even consisting essentially (by weight) of cellulose plant fibers or consisting entirely of cellulose plant fibers, such as fibers of cotton, linen, hemp, jute, or mixtures thereof, which cellulose plant fibers are naturally hydrophilic or are suitably processed to be hydrophilic (or have increased hydrophilicity) and are processed to have a suitable soft feel against the skin. In some cases, plant-based fibers may be preferred to appeal to consumers' preference for natural products. In other examples, semi-synthetic fibers derived from cellulose materials, such as rayon (for the purposes of this document, "rayon" includes viscose fiber, lyocell fiber, MODAL (a product of Lenzing AG, Lenzing, Austria), and cuprammonium rayon) may be included as nonwoven components.

[0084] The nonwoven web may be formed via any suitable method by which limited length fibers (e.g., staple fibers) may be distributed and accumulated onto a forming belt in a controlled manner to form a batt having a desired fiber distribution and achieving a desired basis weight. Suitable methods may include carding, air-laying, and wet-laying. The batt may be processed to consolidate the fibers and entangle them in the z-direction by methods that may include calendering, needling, and water entanglement via a water jet.

[0085] In some examples, a topsheet cut from a nonwoven fabric may be preferred, the nonwoven fabric comprising plant fibers such as cotton fibers or consisting primarily (by weight) of plant fibers or consisting entirely of plant fibers. In some examples, the nonwoven web material may be formed via a carding process. In other examples, the nonwoven web material may be formed via an airlaid or wetlaid process. In some examples, the nonwoven web material may be a spunbond web that includes monocomponent continuous fibers spun from a polymeric resin, or alternatively, bicomponent or multicomponent fibers, or a blend of monocomponent fibers spun from different polymeric resins, or any combination thereof. In some examples, the web may be formed in a coforming process where a limited length of plant-based fibers is physically blended or mixed with a longer but indeterminate length stream of spun fibers, spun from a polymeric resin, and placed on a forming belt to form the web, as described in, for example, US 8,017,534; US 4,100,324; US 2003 / 0200991; US 5,508,102; US 2003 / 0211802; EP 0 333 228; WO 2009 / 10938; US 2017 / 0000695; US 2017 / 0002486; US 9,944,047; 2017 / 0022643 and US 2018 / 0002848.

[0086] To ensure that fluid contacting the top (wearer-facing) surface of the hydrophilic topsheet will move appropriately quickly in the z-direction via capillary action to the bottom (outward-facing) surface of the topsheet, where the fluid can be wicked into the absorbent structure, it may be important to ensure that the nonwoven web material forming the topsheet has an appropriate weight / volume density, reflective of the appropriate presence of void channels among and between the constituent fibers, through which the fluid can move within the nonwoven material. A nonwoven having overly densely consolidated fibers can have an insufficient number and / or volume of void channels, and the nonwoven can block rather than facilitate rapid z-direction fluid movement. On the other hand, a nonwoven having fibers that are not sufficiently consolidated to provide sufficient fiber-to-fiber contact and / or sufficiently small void channels can provide insufficient potential to wick in the z-direction via capillary action. In examples where the nonwoven web material comprises cotton fibers or consists primarily or entirely of cotton fibers, to balance the priorities of fluid concealability and mechanical strength (required for processing), relative to limiting the amount of topsheet material through which the liquid must move in the z-direction to reach the underlying absorbent structure, it may be desirable for the web to have a basis weight of from about 20 gsm to about 50 gsm, more preferably from about 25 gsm to about 45 gsm, and even more preferably from about 30 gsm to about 40 gsm. In combination, it may be desirable for the web to have a density of from about 74 kg / m3 to about 110 kg / m3, and more preferably from about 83 kg / m3 to about 101 kg / m3, where the density is calculated as the basis weight divided by the thickness (z-direction thickness, measured using the thickness measurement method described below). Alternatively, or in combination with the control of the above values, the thickness of the topsheet material can be controlled to balance the competing demands of opacity and bulk (which require higher thicknesses) with the limitation on the z-direction distance through which the discharged fluid must travel from the wearer-facing surface through the topsheet to the outward-facing surface to reach the underlying absorbent structure. Thus, it may be desirable to control the manufacture of the topsheet material to produce a topsheet material having a thickness of from about 0.20 mm to about 0.60 mm, more preferably from about 0.25 mm to about 0.55 mm, and even more preferably from about 0.30 mm to about 0.45 mm. For the purposes of this article, the thickness is measured using the thickness measurement method described below.

[0087] After separation from the cotton boll, cotton fibers are naturally hydrophobic due to the presence of natural wax and oil compounds on the fiber surface. After ginning to separate the cotton fibers from the seeds, the raw cotton fiber tufts (stored and transported in bales) typically contain a large amount of impurities (particles, small pieces of plant matter, etc.) trapped within the fiber matrix and / or adhered to the wax and oil, which both discolor the cotton fibers and render them unsuitable for many uses. In order to make the raw cotton fibers commercially available for most uses, the fibers must first be processed in several steps to remove the impurities. Typical methods also remove the natural wax and oil and render the cotton fibers hydrophilic. Hydrophobic agents such as oil, wax, or silicone can be reintroduced to make the cotton fibers and cotton-based fiber structures hydrophobic and non-absorbent, but for the purposes of this article, an unperforated hydrophobic cotton-based topsheet would be inappropriate because it would not properly accept and wick away the discharged fluid.

[0088] After processing to remove the impurities, the cotton fiber tufts will be further mechanically processed to convert them into their intended final use conditions and structures. Due to their hydrophilic nature, any processed cotton fiber tufts, whether presented as a textile / fabric, paper product, nonwoven fiber web product, or a component of an absorbent product, will absorb aqueous fluids to some extent and will exhibit capillary wicking characteristics.

[0089] Rayon fibers are made from regenerated cellulose. At the molecular level, it is chemically similar to cotton fibers. At the fiber level, rayon fibers can be given complex surface geometries and a large amount of curvature or crimp, and are naturally hydrophilic. Rayon fiber tufts typically have absorption characteristics that exceed those of equal cotton fiber tufts.

[0090] The absorbency and wicking performance can vary depending on the way in which the fibers are further processed and can be manipulated by such means. Factors such as the consolidation level (i.e., compaction) of the fiber tufts in the end structure and the orientation of the individual fibers within the end structure can affect the absorbency and wicking performance.

[0091] Accordingly, for the purposes contemplated herein, in combination with being given a suitable basis weight, density, and / or thickness as described above, it may be desirable for the cotton- and / or rayon-based nonwoven web material used to form the topsheet 20 to be formed via a nonwoven web manufacturing process in which a substantial number of the fibers are given a direction of orientation that includes some z-direction orientation rather than an orientation that is predominantly biased along the machine direction or the x-y plane in which the web structure is formed. After any suitable process (e.g., spunbonding, air-laying, wet-laying, carding, etc.) in which the fibers are distributed and laid in a batt on a horizontal forming belt, an additional process step may be employed that forces some of the fibers or portions thereof to reorient in the z direction. For example, suitable process steps may include needling and hydroentangling. Hydroentangling may be desirable because of its effectiveness in reorienting the fibers while causing less fiber breakage and forming less broken fiber lint and surface fuzz (free fiber ends extending from the main structure of the web), where the high-speed jets of water are directed at the batt as it is conveyed past an array of fine high-speed water jets on a porous belt or drum. A vacuum dewatering system (where air is suctioned in the z direction through the web into and through an array of orifices or holes in the drum or belt that conveys the batt, thereby pulling the ejected water with it) may be desirable because it tends to form, add, open, and / or clear small z-direction channels within the fiber matrix of the web in a pattern generally corresponding to the orifices or holes. Without intending to be bound by theory, it is believed that an increased number of fibers (or portions thereof) oriented in the z direction and z-direction channels enhance the ability and tendency of the web to wick aqueous fluids in the z direction. In the topsheet, this would mean that the material can more readily wick aqueous fluids from the topsheet's wearer-facing surface to the topsheet's outward-facing surface, i.e., directly downward into the underlying absorbent structure, and thus less fluid will be wicked along the x-y plane directions (resulting in lateral and / or longitudinal spreading of stains from the discharged fluid).

[0092] For the purposes of this disclosure, depending on the degree of x-y plane deformation to be imparted as described herein, in some cases, a nonwoven fibrous web precursor of the topsheet may be preferred, which is partially or predominantly or even completely formed of continuous fibers (sometimes referred to as "filaments") spun from a polymer resin and / or regenerated cellulose (rayon). (As used herein, "continuous" fibers will be understood to be fibers that are not cut into short fiber lengths, but are continuously spun and accumulated without cutting or chopping to form a batt on a moving forming belt in a continuous process. The batt is then consolidated and bonded (e.g., via calendering and thermocompression point bonding) to form an adherent web. It should be understood that the fibers do not have an infinite length, but typically have a variable infinite length that is substantially greater than the short fiber length. The method for forming such webs is sometimes referred to as the "spunbond" method and is described in the art. Without being bound by theory, it is believed that the spunbond web or topsheet formed therefrom may be better adapted to the deformation methods described herein because it allows for deformation / plastic elongation along the x-y plane while better maintaining cohesion and structural integrity compared to webs formed primarily of shorter length staple fibers and / or natural plant fibers such as cotton.)

[0093] Absorbent structure

[0094] The absorbent structure 40 of the present disclosure may be given any suitable shape, including but not limited to oval, discorectangle, rectangular, asymmetric, and hourglass shapes. For example, in some configurations, the absorbent structure 40 may have a contoured shape, such as being narrower in the middle region than in the end regions. As another example, the absorbent structure may have a tapered shape, having a wider portion in one end region of the pad and tapering to a narrower end region at the other end region of the pad. In the case where the article is an absorbent pad intended for use by females, it may be desirable for the rear end region to be wider and the front end region to be narrower. In the case where the article is an absorbent pad intended for use by males, it may be desirable for the rear end region to be narrower and the front end region to be wider. The absorbent structure 40 may include different stiffnesses in the longitudinal direction and the lateral direction.

[0095] The configuration and construction of the absorbent structure 40 may vary (e.g., the absorbent structure 40 may have different thickness zones, hydrophilic gradients, superabsorbent gradients, or lower average density and lower average basis weight collection zones). Additionally, the size and absorbent capacity of the absorbent structure 40 may also vary to accommodate a variety of wearers. However, the total absorbent capacity of the absorbent structure 40 should be compatible with the design load and intended use of the absorbent article.

[0096] In some forms, the absorbent structure 40 may include multiple multifunctional layers. For example, the absorbent structure 40 may include a core wrapper (not shown) for encapsulating other layers. The core wrapper may be formed of one or two segments of nonwoven material, a substrate, a laminate, a film, or other materials. In some examples, the core wrapper may be formed of a single material or laminate that at least partially wraps around itself.

[0097] The absorbent structure 40 may include one or more adhesives, for example to help secure the absorbent gelling material / superabsorbent polymer (SAP) or other absorbent materials included within the absorbent structure.

[0098] Absorbent structures having various absorbent structure / core designs and containing a relatively high amount of SAP are disclosed in US 2008 / 0312622A1; US 5,599,335; EP 1,447,066; WO 95 / 11652; and WO 2012 / 052172 by Hundorf et al. These can be used to construct superabsorbent layers.

[0099] Additions to the absorbent structures of the present disclosure are envisioned. Specifically, potential additions to current multilayer absorbent structures are described in US 4,610,678; US 4,673,402; US 4,888,231 and US 4,834,735. The absorbent structure may further include additional layers simulating a dual-core system that includes a collection / distribution structure of chemically enhanced fibers positioned above the absorbent structure, as described in US 5,234,423 and US 5,147,345. These are useful to a certain extent and do not counteract or conflict with the functions of the laminates of the absorbent structures of the present invention described below.

[0100] Some examples of suitable absorbent structures 40 for use in the absorbent articles of the present disclosure are described in US 2018 / 0098893 and US 2018 / 0098891. Examples of possible suitable configurations are further described and depicted in US application serial number 16 / 831,851.

[0101] In some configurations, the absorbent structure 40 may be formed of or include a layer of absorbent open-cell foam material. In some examples, the foam material may include at least a first layer and a second layer of absorbent open-cell foam material (e.g., 40t, 40b, see Figure 4D ) and these sub-layers are in direct face-to-face contact with each other. In such examples, the sub-layer facing the wearer may be a relatively large open-cell foam material, and the sub-layer facing outwards may be a relatively small open-cell foam material for purposes explained in more detail below.

[0102] The open-cell foam material can be a foam material manufactured by the polymerization of a continuous oily monomer phase via a water-in-oil high internal phase emulsion (“HIPE”). For the purposes herein, a HIPE is a two-phase water-in-oil emulsion where the ratio of water to oil is greater than about 2.85:1, i.e., about 74% aqueous phase / dispersed phase (by volume). Due to this relatively high ratio of the aqueous phase to the oil phase, upon emulsification sufficient to produce a foam of the type contemplated herein (i.e., average cell size 1 micron to 300 microns), the dispersed aqueous phase will have a droplet form that is forced into a polyhedral form due to close packing, separated by thin film walls formed from the oil phase / continuous phase. Examples of such open-cell HIPE foam materials are found in the absorbent structure of ALWAYS INFINITY brand feminine hygiene pads currently manufactured and sold by The Procter & Gamble Company, Cincinnati, Ohio. The open-cell foam material as described herein may be preferred for the purposes herein because it can be manufactured to be relatively friable under tension such that it can neatly break along ordered lines during the deformation process described herein to form sheets of approximate or substantially uniform size and shape.

[0103] The oil phase of the HIPE is continuous and includes monomers to be polymerized and an emulsifier that aids in the production and stabilization of the HIPE. The oil phase may also include one or more photoinitiators. The monomer component may be included in an amount of about 80% to about 99% and in some examples about 85% to about 95% by weight of the oil phase. The emulsifier component, which is soluble in the oil phase and is suitable for forming a stable water-in-oil emulsion, may be included in the oil phase in an amount of about 1% to about 20% by weight of the oil phase. The emulsion may be formed at an emulsification temperature of about 20°C to about 130°C and in some examples about 50°C to about 100°C.

[0104] Generally speaking, the monomers may be included in an amount of about 20% to about 97% by weight of the oil phase and may include at least one substantially water-insoluble monofunctional acrylic alkyl ester or methacrylic alkyl ester. For example, monomers of this type may include C4-C18 acrylic alkyl esters and C2-C18 methacrylic alkyl esters such as ethylhexyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, isodecyl acrylate, tetradecyl acrylate, benzyl acrylate, nonylphenyl acrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, tetradecyl methacrylate, and octadecyl methacrylate.

[0105] The oil phase may also contain from about 2% to about 40%, and in certain examples from about 10% to about 30% by weight of the oil phase, of a substantially water-insoluble polyfunctional crosslinked acrylate or methacrylate. This crosslinking comonomer or crosslinking agent is added to impart strength and elasticity to the resulting HIPE foam. Examples of this type of crosslinking monomer include monomers containing two or more activated acrylate, methacrylate groups, or combinations thereof. Non-limiting examples of such groups include 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,12-dodecanediol dimethacrylate, 1,14-tetradecanediol dimethacrylate, ethylene glycol dimethacrylate, neopentyl glycol diacrylate (2,2-dimethylpropanediol diacrylate), hexanediol acrylate methacrylate, glucose pentaacrylate, sorbitan pentaacrylate, and the like. Other examples of crosslinking agents include mixtures of acrylate and methacrylate moieties, such as ethylene glycol acrylate-methacrylate and neopentyl glycol acrylate-methacrylate. The ratio of methacrylate:acrylate groups in the mixed crosslinking agent can vary from 50:50 to any other ratio as desired.

[0106] Any third substantially water-insoluble comonomer from about 0 wt% to about 15 wt%, and in certain examples from about 2 wt% to about 8 wt% by weight of the oil phase, can be added to the oil phase to modify the properties of the HIPE foam. In some cases, it may be desirable to have a "toughening" monomer to impart toughness to the resulting HIPE foam. These include monomers such as styrene, vinyl chloride, vinylidene chloride, isoprene, and chloroprene. Without wishing to be bound by theory, it is believed that such monomers assist in stabilizing the HIPE (also referred to as "curing") during polymerization to provide a more uniform and better-shaped HIPE foam, resulting in better toughness, tensile strength, abrasion resistance, etc. Monomers can also be added to impart flame retardancy, as disclosed, for example, in US 6,160,028. Monomers can be added to impart color (e.g., vinyl ferrocene); to impart fluorescent properties; to impart radiation resistance; to impart radiation impermeability (e.g., lead tetraacrylate); to dissipate charge; to reflect incident infrared light; to absorb radio waves; to render the surface of the HIPE foam ribs or cell walls wettable; or for any other desired property in the HIPE foam. In some cases, these additional monomers can slow down the overall process of the HIPE turning into a HIPE foam, and a trade-off is necessary if the desired property is to be imparted. Thus, such monomers can also be used to slow down the polymerization rate of the HIPE. Examples of this type of monomer include styrene and vinyl chloride.

[0107] The oil phase may also include an emulsifier to facilitate emulsification and stabilize the HIPE. Emulsifiers useful in HIPEs may include: (a) sorbitan monoesters of branched C16-C24 fatty acids; straight-chain unsaturated C16-C22 fatty acids; and straight-chain saturated C12-C14 fatty acids, such as sorbitan monooleate, sorbitan monomyristate, and sorbitan monoesters, sorbitan monolaurate, diglycerol monooleate (DGMO), polyglycerol monoisostearate (PGMIS), and polyglycerol monomyristate (PGMM); (b) polyglycerol monoesters of branched C16-C24 fatty acids, straight-chain unsaturated C16-C22 fatty acids, or straight-chain saturated C12-C14 fatty acids, such as diglycerol monooleate (e.g., diglycerol monoesters of C18:1 fatty acids), diglycerol monomyristate, diglycerol monoisostearate, and diglycerol monoesters; (c) diglycerol monoaliphatic ethers of branched C16-C24 alcohols, straight-chain unsaturated C16-C22 alcohols, and straight-chain saturated C12-C14 alcohols, and mixtures of these emulsifiers. See US 5,287,207 and US 5,500,451. Another emulsifier that may be used is polyglycerol succinate (PGS), which is formed from alkyl succinates, glycerol, and triglycerol.

[0108] Such emulsifiers and combinations thereof may be added to the oil phase such that they constitute from about 1% to about 20%, in some examples from about 2% to about 15%, and in some other examples from about 3% to about 12% by weight of the oil phase. In some examples, a co-emulsifier may also be used to provide additional control over cell size, cell size distribution, and emulsion stability, especially at higher temperatures, such as, for example, greater than about 65 °C. Examples of co-emulsifiers include phosphatidylcholine and phosphatidylcholine-containing compositions, aliphatic betaines, long-chain C12-C22 dialiphatic quaternary ammonium salts, short-chain C1-C4 dialiphatic quaternary ammonium salts, long-chain C12-C22 dialkanoyl (enoyl)-2-hydroxyethyl, short-chain C1-C4 dialiphatic quaternary ammonium salts, long-chain C12-C22 dialiphatic imidazoline quaternary ammonium salts, short-chain C1-C4 dialiphatic imidazoline quaternary ammonium salts, long-chain C12-C22 monoaliphatic benzyl quaternary ammonium salts, long-chain C12-C22 dialkanoyl (enoyl)-2-aminoethyl, short-chain C1-C4 monoaliphatic benzyl quaternary ammonium salts, short-chain C1-C4 monohydroxy aliphatic quaternary ammonium salts. In some examples, ditallow dimethyl ammonium methyl sulfate (DTDMAMS) may be used as a co-emulsifier.

[0109] Any photoinitiator included may be included in an amount of from about 0.05% to about 10% and in some examples from about 0.2% to about 10% by weight of the oil phase. Lower amounts of photoinitiator allow light to better penetrate the HIPE foam, which can enable polymerization deeper into the HIPE foam. However, if the polymerization is carried out in an oxygen-containing environment, it may be desirable to have sufficient photoinitiator to initiate the polymerization and overcome the inhibition by oxygen. The photoinitiator can respond quickly and efficiently to a light source to generate free radicals, cations, and other species capable of initiating the polymerization reaction. The photoinitiator selected for forming the foam within the scope of the present disclosure can absorb UV light having a wavelength of from about 200 nanometers (nm) to about 800 nm, and in certain examples from about 250 nm to about 450 nm. If the photoinitiator is in the oil phase, suitable types of oil-soluble photoinitiators include benzyl ketals, α-hydroxyalkyl phenyl ketones, α-aminoalkyl phenyl ketones, and acylphosphine oxides. Examples of photoinitiators include the combination of 2,4,6-[trimethylbenzoyl diphosphine] oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one (a 50:50 blend of both is sold by Ciba Speciality Chemicals, Ludwigshafen, Germany under the trade name DAROCUR ® 4265); benzyl dimethyl ketal (sold by Ciba Geigy under the name IRGACURE 651); α,α-dimethoxy-α-hydroxyacetophenone (sold by Ciba Speciality Chemicals under the trade name DAROCUR ® 1173); 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (sold by Ciba SpecialityChemicals under the trade name IRGACURE ® 907); 1-hydroxycyclohexyl phenyl ketone (sold by Ciba SpecialityChemicals under the trade name IRGACURE ® 184); bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (sold by Ciba Speciality Chemicals under the name IRGACURE 819); diethoxyacetophenone and 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-methylpropyl) ketone (sold by Ciba Speciality Chemicals under the trade name IRGACURE ® 2959); and oligo[2-hydroxy-2-methyl-1-[4-(1-methylethenyl)phenyl]propanone] (sold by Lamberti spa, Gallarate, Italy under the trade name ESACURE ® KIP EM).

[0110] The dispersed aqueous phase of the HIPE mainly contains water and may also contain one or more components, such as initiators, photoinitiators or electrolytes, where in certain examples, the one or more components are at least partially water-soluble.

[0111] One component contained in the aqueous phase can be a water-soluble electrolyte. The aqueous phase can contain from about 0.2% to about 40%, in certain examples from about 2% to about 20%, by weight of the aqueous phase of the water-soluble electrolyte. The electrolyte minimizes the tendency for the mainly oil-soluble monomers, comonomers and crosslinkers to also dissolve in the aqueous phase. Examples of electrolytes include chlorides or sulfates of alkaline earth metals (such as calcium or magnesium), and chlorides or sulfates of alkali metals (such as sodium). Such electrolytes can contain buffers for controlling the pH during the polymerization process, and the buffers include inorganic counterions such as phosphates, borates and carbonates and mixtures thereof. Water-soluble monomers can also be used in the aqueous phase, examples being acrylic acid and vinyl acetate.

[0112] Another component that can be contained in the aqueous phase is a water-soluble free radical initiator. Based on the total moles of polymerizable monomers present in the oil phase, the initiator can be present in an amount of up to about 20 mol%. In certain examples, based on the total moles of polymerizable monomers in the oil phase, the initiator can be included in an amount of about 0.001 mol% to about 10 mol%. Suitable initiators include ammonium persulfate, sodium persulfate, potassium persulfate, 2,2'-azobis(N,N'-dimethylisobutylamidine) dihydrochloride, azo initiators, redox pairs such as persulfate-bisulfate, persulfate-ascorbic acid and other suitable redox initiators. In certain examples, to reduce the likelihood of premature polymerization that can clog the emulsion system, the initiator can be added to the monomer phase near the end of the emulsification step or shortly after the end of the emulsification step.

[0113] When included in the aqueous phase, the photoinitiator can be at least partially water-soluble and can constitute between about 0.05% and about 10%, and in certain examples between about 0.2% and about 10% by weight of the aqueous phase. A lower amount of photoinitiator allows light to better penetrate the HIPE foam, which can enable polymerization deeper into the HIPE foam. However, if the polymerization is carried out in an oxygen-containing environment, there should be sufficient photoinitiator to initiate the polymerization and overcome the inhibition of oxygen. The photoinitiator can respond quickly and efficiently to a light source, thereby generating free radicals, cations, and other substances capable of initiating the polymerization reaction. The photoinitiator selected for forming the foam within the scope of the present disclosure can absorb UV light with a wavelength of about 200 nanometers (nm) to about 800 nm, in certain examples about 200 nm to about 350 nm, and in certain examples about 350 nm to about 450 nm. If the photoinitiator is to be included in the aqueous phase, suitable types of water-soluble photoinitiators can include benzophenone, benzoin, and thioxanthone. Examples of photoinitiators include 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride; dehydrated 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate; 2,2'-azobis(1-imino-1-pyrrolidino-2-ethylpropane) dihydrochloride; 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; 2,2'-azobis(2-methylpropionamidine) dihydrochloride; 2,2'-dicarboxymethoxydibenzylideneacetone, 4,4'-dicarboxymethoxydibenzylideneacetone, 4,4'-dicarboxymethoxydibenzylidene cyclohexanone, 4-dimethylamino-4'-carboxymethoxydibenzylideneacetone; and 4,4'-disulfonylmethoxydibenzylideneacetone. Other suitable photoinitiators that can be used are listed in US 4,824,765.

[0114] In addition to the foregoing components, other components can also be included in the aqueous or oil phase of the HIPE. Examples include antioxidants such as hindered phenols, hindered amine light stabilizers; plasticizers such as dioctyl phthalate, dinonyl sebacate; flame retardants such as halogenated hydrocarbons, phosphates, borates, inorganic salts such as antimony trioxide or ammonium phosphate or magnesium hydroxide; dyes and pigments; fluorescent agents; filler particles such as starch, titanium dioxide, carbon black, or calcium carbonate; fibers; chain transfer agents; odor absorbers such as activated carbon particles; dissolved polymers; dissolved oligomers; and the like.

[0115] The HIPE foam is produced by the polymerization of monomers comprising the continuous oil phase of the HIPE. In certain examples, the HIPE foam layer can be manufactured to have one or more sub-layers (e.g., 40t, 40b, see Figure 4D), and can be a homogeneous or heterogeneous polymeric open-cell foam. Homogeneity and heterogeneity relate to different layers within the same HIPE foam, which are similar in the case of homogeneous HIPE foam and different in the case of heterogeneous HIPE foam. A heterogeneous HIPE foam can comprise at least two different sub-layers that differ in their chemical composition, physical properties, or both; for example, the sub-layers can differ in one or more of foam density, polymer composition, specific surface area, or pore size (also referred to as cell size). For example, for a HIPE foam, if the difference relates to pore size, the average pore size in the respective sub-layers can differ by at least about 20%, in some examples at least about 35%, and in other examples at least about 50%. As another example, if the difference in the sub-layers of a HIPE foam layer relates to density, the density of the layers can differ by at least about 20%, in some examples at least about 35%, and in other examples at least about 50%. For example, if one layer of a HIPE foam has a density of 0.020 g / cm 3 , then another layer can have at least about 0.024 g / cm 3 or less than about 0.016 g / cm 3 , in some examples at least about 0.027 g / cm 3 or less than about 0.013 g / cm 3 and in other examples at least about 0.030 g / cm 3 or less than about 0.010 g / cm 3 . If the difference between the layers relates to the chemical composition of the HIPE or HIPE foam, the difference can reflect a difference in the relative amounts of at least one monomer component, for example differing by at least about 20%, in some examples at least about 35%, and in further examples at least about 50%. For example, if one sub-layer of a HIPE or HIPE foam consists of about 10% styrene in its formulation, then another sub-layer of the HIPE or HIPE foam can consist of at least about 12% and in some examples at least about 15%.

[0116] A HIPE foam layer configured to have different sub-layers formed from different HIPEs can provide a HIPE foam layer with a range of desired performance characteristics. For example, when used in an absorbent article, a HIPE foam layer including a first foam sub-layer and a second foam sub-layer, where the first foam sub-layer has a relatively larger pore size or cell size than the second sub-layer, can absorb incoming fluids faster than the second sub-layer. For example, when using a HIPE foam layer to form the absorbent structure of a feminine hygiene pad, the first foam sub-layer can be laminated on a second foam sub-layer having a relatively smaller pore size compared to the first foam sub-layer, and the second foam sub-layer exerts a greater capillary pressure and sucks the collected fluid from the first foam sub-layer, thereby restoring the ability of the first foam sub-layer to collect more fluid from above. The HIPE pore size can range from about 1 µm to about 200 µm, and in some examples can be less than about 100 µm. The HIPE foam layer of the present disclosure having two major parallel surfaces can be from about 0.5 mm to about 10 mm thick, and in some examples from about 2 mm to about 10 mm. The desired thickness of the HIPE foam layer will depend on the material used to form the HIPE foam layer, the speed at which the HIPE is deposited on the belt, and the intended use of the resulting HIPE foam layer. An example of an open-cell HIPE foam material having two sub-layers can be seen in the absorbent structure of the ALWAYS INFINITY brand feminine hygiene pad currently manufactured and sold by Procter & Gamble Company of Cincinnati, Ohio.

[0117] The HIPE foam layer of the present disclosure is relatively open-cell. This means that the individual cells or pores of the HIPE foam layer are substantially unobstructed fluidly connected to adjacent cells. The cells in such a substantially open-cell HIPE foam structure have openings or windows between the cells that are large enough such that fluids can easily transfer from one cell to another within the HIPE foam structure. For the purposes of the present disclosure, a HIPE foam is considered "open-cell" if at least about 80% of the cells in the HIPE foam having a pore size of at least 1 µm are fluidly connected to at least one adjacent cell.

[0118] In addition to being open-cell, in some examples, the HIPE foam is also adapted to have sufficient hydrophilicity to allow the HIPE foam to absorb aqueous fluids. In some examples, the inner surface of the HIPE foam can be made hydrophilic by residual hydrophilizing surfactants or salts remaining in the HIPE foam after polymerization, or by selected post-polymerization HIPE foam treatment procedures such as those described in the references cited herein.

[0119] In some configurations, such as when used to form an absorbent structure for a feminine hygiene pad, the HIPE foam layer can be flexible and exhibit an appropriate glass transition temperature (Tg). Tg represents the transition midpoint between the glassy and rubbery states of a polymer. Generally speaking, a HIPE foam with a Tg above the use temperature can be strong, but will also be relatively rigid and potentially prone to breakage (fragile). In certain examples, the regions of the HIPE foam of the present disclosure that exhibit a relatively high Tg or excessive brittleness will be discontinuous. Since these discontinuous regions will generally also exhibit high strength, they can be prepared at a lower density without compromising the overall strength of the HIPE foam.

[0120] A HIPE foam intended for applications that require flexibility should contain at least one continuous region with the lowest possible Tg, as long as the overall HIPE foam has acceptable strength at the use temperature. In certain examples, for a foam used under approximately ambient temperature conditions, the Tg of this region will be below about 40 °C; in certain other examples, the Tg will be below about 30 °C. For a HIPE foam used in applications where the use temperature is above or below ambient temperature, the Tg of the continuous region can be no more than 10 °C higher than the use temperature, the same as the use temperature in certain examples, and about 10 °C lower than the use temperature when flexibility is desired in additional examples. Therefore, monomers that provide the corresponding polymer with a lower Tg are selected as much as possible.

[0121] HIPE foams that can be used to form absorbent structures and / or sublayers within the purview of the present disclosure, as well as materials and methods for their manufacture, also include but are not necessarily limited to those foams and methods described in the following patents: US 10,045,890, US 9,056,412, US 8,629,192, US 8,257,787, US 7,393,878, US 6,551,295, US 6,525,106, US 6,550,960, US 6,406,648, US 6,376,565, US 6,372,953, US 6,369,121, US 6,365,642, US 6,207,724, US 6,204,298, US 6,158,144, US 6,107,538, US 6,107,356, US 6,083,211, US 6,013,589, US 5,899,893, US 5,873,869, US 5,863,958, US 5,849,805, US 5,827,909, US 5,827,253, US 5,817,704, US 5,817,081, US 5,795,921, US 5,741,581, US 5,652,194, US 5,650,222, US 5,632,737, US 5,563,179, US 5,550,167, US 5,500,451, US 5,387,207, US 5,352,711; US 5,397,316, US 5,331,015, US 5,292,777, US 5,268,224, US 5,260,345, US 5,250,576, US 5,149,720, US 5,147,345, and US 2005 / 0197414, US 2005 / 0197415, US 2011 / 0160326, US 2011 / 0159135, US 2011 / 0159206, US 2011 / 0160321, and US 2011 / 0160689, which are incorporated herein by reference to the extent not inconsistent with the present text.

[0122] As Figure 2As reflected in, the absorbent structure 40 formed of HIPE foam may include one or more patterns of apertures 43, including at least a first pattern disposed at the intersection of the longitudinal axis 100 and the lateral axis 200 of the cover pad within the intended discharge location. The apertures 43 may be punched, cut, or otherwise formed through the entire z-direction depth of the HIPE foam absorbent structure, or only through the layer facing the wearer or partially into its wearer-facing portion. When the HIPE foam absorbent structure is disposed in direct contact with a topsheet as described herein, in the absence of an intervening acquisition layer formed of another material, the apertures 43 may serve as a set of reservoirs to receive, temporarily hold, and facilitate the rapid discharge of a relatively small amount of menstrual fluid until the HIPE foam has had sufficient time to distribute and absorb the fluid via capillary action. Additionally, such apertures also help reduce the flexural stiffness of the absorbent structure, which can help improve the comfort of the pad for the wearer. An aperture pattern having an average radius or other maximum dimension of 1.0 mm to 4.0 mm and more preferably 1.5 mm to 3.5 mm may be included, for example, within the area occupied by the adhesive region 25. The pattern may include a numerical density of 3.0 to 9.0 apertures / cm 2 and more preferably 4.0 to 8.0 apertures / cm 2 of apertures. In selecting the appropriate average size, numerical density, and surface area occupied by the aperture pattern, the manufacturer may wish to balance the volume of the desired "reservoirs" with the need to hold the absorbent material in a position proximate to the intended discharge location. Additional details regarding such aperture configurations in combination with examples of suitable absorbent structures can be found in US8,211,078.

[0123] The absorbent structure 40 formed from HIPE foam should be imparted with a sufficient capillary work potential in the absorbent mode (CWPA) (as described below) to have the ability to effectively draw off the fluid discharged from the topsheet during the use / wearing time of the menstrual pad, which is common and expected for feminine hygiene pads, such as 4 to 8 hours. As described below, the CWPA of the material is partly affected by its volume. Thus, it may be desirable for the absorbent structure 40 formed from HIPE foam to have a thickness (before wetting) that provides a satisfactory volume for a standard-sized pad. Of course, relatively thick pads can be manufactured, but this is generally considered undesirable for daytime use given the expectations for flexibility / flexibility and thinness, and the expectations for comfort and discretion under clothing. Manufacturing must balance these competing objectives. Thus, for a feminine hygiene pad having a HIPE foam absorbent structure as contemplated herein, it may be desirable for the layer to have a paper thickness of about 1 mm to about 5 mm, or more preferably about 1.5 mm to about 3.5 mm, or even more preferably about 2.0 mm to about 3.0 mm, over most of its surface area facing the wearer (before wetting). (The thickness of the HIPE foam layer can be visually measured to any degree considered useful by means of magnification / microscopy and / or photography or any other facilitating technology and equipment.) If the absorbent structure 40 includes two sub-layers as described herein, it may be desirable for the upper sub-layer 40t to have a thickness (before wetting) of about 0.64 mm to about 3.2 mm, or preferably about 0.96 mm to about 2.24 mm, or even more preferably about 1.28 mm to about 1.92 mm; and it may be desirable for the lower sub-layer 40b to have a thickness (before wetting) of about 0.16 mm to about 0.80 mm, or more preferably about 0.24 mm to about 0.56 mm, or even more preferably about 0.32 mm to about 0.48 mm.

[0124] In some configurations, the absorbent structure 40 may consist of or include a heterogeneous layer composed of an absorbent foam material (such as a HIPE foam material, as described above), the heterogeneous layer having a structure that has polymerized and thus formed around, within, and / or within the fiber matrix of a nonwoven web material. Examples of such heterogeneous layers are depicted and described in US2017 / 0119587; US2017 / 0119596; US2017 / 0119597; US2017 / 0119588; US2017 / 0119593; US2017 / 0119594; US2017 / 0119595; and US2017 / 0199598.

[0125] Absorption characteristics and interface between the top sheet and the absorbent structure

[0126] The affinity and absorbency of the absorbent / hydrophilic structure for the aqueous fluid can be characterized in part by its capillary absorption pressure. The capillary absorption pressure (CAP) can be measured according to the steps in the capillary work potential measurement method described below. It is a value that reflects the magnitude of the tendency of the structure to suck the aqueous fluid. It should be understood that the graph of the CAP of the absorbent structure versus the saturation level will have an initial maximum (at the start of fluid absorption) and will decrease as the structure sucks the fluid and approaches its full absorption capacity (i.e., full saturation).

[0127] The resistance to desorption or the tendency of the absorbent / hydrophilic structure to retain the absorbed fluid can be characterized in part by its capillary desorption pressure (CDP). The CDP (which can also be measured according to the steps in the capillary work potential measurement method described below) is a value that reflects the magnitude of the pressure (or pressure difference) required to drive (or suck) out the aqueous fluid absorbed and retained in the structure. It should be understood that the graph of the CDP of the structure versus the saturation level will have an initial minimum (before any fluid is expelled from the structure) and will increase as the fluid leaves it.

[0128] The CAP and CDP of a given structure depend on the degree of hydrophilicity of the solid surfaces within the structure, the interstitial spaces or voids within / between the solid surfaces in the structure, the average size of the cells or pores, and the number of interstitial spaces, cells or pores per unit volume of the structure.

[0129] In order for the layered topsheet / absorbent structure combination to effectively move the discharged fluid away from the wearer in the z-direction from the top surface of the topsheet, in addition to the other conditions described herein, the CAP of the absorbent structure must be greater than the CDP of the topsheet at the absorbed fluid content at the selected level of the topsheet, preferably at a relatively low level. In order for the layered topsheet / absorbent structure combination to move the discharged fluid away from the wearer at an acceptable rate in the z-direction, i.e., such that the topsheet does not have time to wick excessively in the planar direction and thus distribute (i.e., spread) the discharged fluid (resulting in an undesirably large stain on the topsheet) and the wearer does not feel overly wet soon after the fluid is discharged onto the wearer, the capillary absorption pressure of the absorbent structure at, for example, 20% saturation should be greater than the capillary desorption pressure of the topsheet at the same saturation, where the saturation percentage is the percentage of the total pore volume of the material occupied by the fluid and the test fluid is a saline solution as specified in the capillary work potential measurement method described below.

[0130] The total absorbency of a given material structure can also be characterized by its capillary work potential in an absorption mode (CWPA) and an emission or desorption mode (CWPD), as measured using the following capillary work potential measurement method. CWPA is a measure of the work that an absorbent material would do to draw a given amount of aqueous fluid under the conditions of the method. CWPD is a measure of the work required to expel or draw out the aqueous fluid absorbed and retained by the structure under the conditions of the method. For a given hydrophilic and aqueous fluid-absorbing structure, CWPD will be greater than CWPA because the characteristics of the absorbent structure (hydrophilicity; cell / pores size and volume) cause it to tend to retain fluid. The CWPA and CWPD of a given structure are affected by the characteristics and properties that affect CAP and CDP and also by the total volume of void space or voids, cells or pores within the structure. Thus, it should be understood that the CWPA and CWPD of a structure are affected in part by the overall volume (i.e., size) of the structure.

[0131] To ensure that the absorbent structure 40 adequately discharges the fluid absorbed by the topsheet 20 in the topsheet so that both provide a satisfactory pad, the CWPA of the absorbent structure 40 should be greater than the CWPD of the topsheet. If this condition is not met, the absorbent structure will not adequately discharge the fluid from the topsheet to achieve two things: (1) ensure that the topsheet does not retain an unacceptable wet feeling after discharge; and (2) ensure that the topsheet remains dischargeable and has the ability to accept continuous discharge of fluid over a reasonable period of use of the article 10.

[0132] It has been recognized that an absorbent structure formed from a HIPE foam as described herein can be manufactured to have a capillary absorption pressure large enough to draw fluid from an absorbent cotton topsheet at an acceptable rate during repeated discharges (i.e., over a reasonable period of use of the pad).

[0133] In examples where the topsheet is formed in whole or in part from a fibrous web material comprising hydrophilic fibers, the topsheet material may tend to hold fluid on its wearer-facing surface and its outward-facing surface, as well as in and along the interstitial spaces between and on the surfaces of the fibers within the fibrous web material, unless the absorption capacity and absorption pressure of the underlying material are greater than the desorption pressure of the topsheet, as described above; and there is sufficient direct contact between the topsheet and the underlying absorbent structure to enable fluid to move directly from the surfaces of the fibers within the topsheet structure to the surfaces of the material within the underlying absorbent structure such that the underlying absorbent structure can draw fluid from the topsheet. The absorbent material will tend not to release the absorbed fluid until it is fully saturated, unless there is sufficient direct contact with an adjacent material that has a greater affinity for the fluid. Therefore, it is important to provide a structure that is sufficient to maintain adequate contact without impeding fluid movement. Between the material of the topsheet 20 and the material of the absorbent structure 40, at least within the bonding region 25, more preferably over most of the wearer-facing surface area of the absorbent structure 40, and even more preferably over the entire wearer-facing surface area of the absorbent structure 40, no intervening material layer or structure, or at least no intervening material layer or structure that is less absorbent than the topsheet or more absorbent than the absorbent structure, should be inserted, which is different from the systems provided in many current feminine hygiene pads that include a distinct fluid acquisition / distribution material layer between the absorbent material of the topsheet and the absorbent structure.

[0134] In some examples, sufficient direct contact between the topsheet 20 and the absorbent structure 40 can be achieved by depositing an adhesive between the topsheet 20 and the absorbent structure 40 so as to bond them in a z-directionally adjacent manner. The adhesive can be applied in a pattern or arrangement of adhesive deposits that are interspersed with regions where there is no adhesive (unbonded regions) such that the adhesive holds the two layers in z-directional proximity while the regions retain the absence of adhesive to impede z-directional fluid movement between the layers.

[0135] See Figure 2 , to ensure that the topsheet 20 and the absorbent structure 40 layers remain in sufficient z-directional proximity, at least in the region of the topsheet 20 that is expected to receive fluid discharge, it may be desirable to position the bonding region 25 at the location of the intersection of a longitudinal axis 100 and a lateral axis 200 on the pad. The bonding region 25 should be of sufficient size to reliably be located beneath the expected discharge location during use of the pad, where the placement of the wearer within the undergarment has reasonable minor variations; thus, it may be desirable for the bonding region to have an area of at least about 15 cm 2 , more preferably at least about 30 cm 2 in area. Even more preferably, it may be desirable for the area of the bonding region 25 to be at least half of the total wearer-facing surface area of the absorbent structure 40 (within its perimeter 40a). (Note:Figure 2 is not presented herein as drawn to actual size or scale.)

[0136] See Figures 2 to 3C , to ensure that the topsheet 20 and the absorbent structure 40 maintain sufficient z-direction proximity during use, it may be desirable that within any recognizable first point bond location 27 within the bond area 25 where the topsheet is bonded to the absorbent structure, there is a second recognizable point location where the topsheet is bonded to the absorbent structure, and this second recognizable point location is within a radius of about 10 mm, more preferably within a radius of about 6 mm, about 5 mm, about 4 mm, and even more preferably within a radius r of about 3 mm of the first point location. See Figures 3A to 3C (showing three non-limiting examples), it can be seen that a variety of bonding patterns or arrangements (via adhesive deposits 26 or other bonding mechanisms) can be employed to impart this feature. Within the radius r of each recognizable bond point location 27, there are multiple additional point locations in the examples described where there is a bond between the topsheet and the absorbent structure.

[0137] It should be understood that a continuous film or coating-like deposit of adhesive can be applied to bond the topsheet and the absorbent structure throughout the bond area 25, but such a continuous deposit of adhesive can form an occlusive barrier that will impede the movement of fluid from the topsheet to the absorbent structure. Therefore, preferably, in examples where the bonding mechanism is an adhesive deposit, the deposit is provided in a discontinuous or intermittent pattern or arrangement such that it forms a bond area between the topsheet and the absorbent structure that is interspersed with unbonded areas, as Figures 3A to 3C shown.

[0138] In Figure 3D another example shown, a dense arrangement of relatively small point bond locations can be achieved by spraying a suitable adhesive onto one or both of the outward-facing surface of the topsheet (20) and the wearer-facing surface of the absorbent structure that contacts the outward-facing surface of the topsheet. If the adhesive is appropriately adjusted (e.g., its viscosity), the nozzle is appropriately configured, and the spray rate (liquid volume or weight / time / surface area covered by the sprayed adhesive) is appropriately regulated such that discrete spray droplets strike and adhere to the surface at discrete locations to an appropriately limited extent such that no continuous deposit or continuous film is formed, the sprayed adhesive can form a dense random pattern 27p of discrete point bond locations that falls within the description in the foregoing paragraph above, but does not result in an occlusive film of deposited adhesive that blocks the pores of the underlying absorbent structure or impedes the movement of fluid from the topsheet to the underlying absorbent structure.

[0139] In addition, when the absorbent structure is formed from an open-cell foam, such as the HIPE foam contemplated herein, it may be desirable that the selected adhesive effect adhesion to the absorbent structure not via chemical, dispersive, or diffusive adhesion to the foam layer at the adhesive deposition location, but rather this is achieved by flowing to a limited extent into the pores (at least partially taking on their shape) and curing at such locations to form a mechanical interlock with the pore structure, which mechanical interlocks enable the adhesive to hold the topsheet and / or backsheet to the absorbent structure. Such adhesives may be preferred so as not to alter the molecular structure or composition of the foam material, which could potentially adversely affect its fluid absorption characteristics or mechanical strength. In some configurations, a portion of the adhesive may penetrate into the wearer-facing surface of the foam material and into the garment-facing surface of the topsheet and / or a portion of the adhesive may penetrate into the garment-facing surface of the foam material and into the wearer-facing surface of the backsheet to bond the foam material to the topsheet and / or backsheet. A suitable example may be an adhesive named H2031-C5X, which is a product of Bostik, a division or subsidiary of Arkema Group, Columbes, France.

[0140] Back sheet

[0141] The backsheet 30 may be positioned below or near the outward-facing surface of the absorbent structure 40 and may be joined thereto by any suitable attachment method. For example, the backsheet 30 may be secured to the absorbent structure 40 by a uniform continuous layer of adhesive, a patterned layer of adhesive, or an array of discrete adhesive lines, spirals, or dots. Alternatively, the attachment method may include heat bonding, pressure bonding, ultrasonic bonding, dynamic mechanical bonding, or any other suitable attachment mechanism or combination thereof. In some configurations, it is contemplated that the absorbent structure 40 is not directly joined to the backsheet 30.

[0142] The backsheet 30 may be impervious or substantially impervious to aqueous liquids (e.g., urine, menstrual fluid) and may be made of a thin plastic film, although other liquid-impervious flexible materials may also be used. As used herein, the term "flexible" refers to materials that are compliant and easily conformable to the general shape and contours of the human body. The backsheet 30 may prevent or at least substantially inhibit the fluid absorbed and contained within the absorbent structure 40 from escaping and reaching the clothing articles of the wearer that may contact the pad 10, such as underwear and outerwear. However, in some cases, the backsheet 30 may be made and / or adapted to allow vapor to escape from the absorbent structure 40 (i.e., the backsheet is made breathable), while in other cases, the backsheet 30 may be made so as not to allow vapor to escape (i.e., it is made non-breathable). Thus, the backsheet 30 may include a polymeric film, such as a thermoplastic film of polyethylene or polypropylene. Suitable materials for the backsheet 30 are, for example, thermoplastic films having a thickness of from about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mil). Any suitable backsheet known in the art may be used in the present invention.

[0143] Some suitable examples of materials suitable for forming the backsheet are described in US 5,885,265, US 4,342,314, and US 4,463,045. Suitable single-layer breathable backsheets for use herein include, for example, those described in GB A 2184 389, GBA 2184 390, GB A 2184 391, US 4,591,523, US 3,989,867, US 3,156,242, WO 97 / 24097, US 6,623,464, US 6,664,439, and US 6,436,508.

[0144] The backsheet 30 may have two layers: a first layer including a vapor-permeable apertured film layer and a second layer including a breathable microporous film layer, as described in US 6,462,251. Other suitable examples of double-layer or multi-layer breathable backsheets for use herein include those described in US 3,881,489, US 4,341,216, US 4,713,068, US 4,818,600, EP 203 821, EP 710 471, EP 710 472, and EP 0 793 952.

[0145] For the purposes described herein, it may be preferred that the film from which the backsheet is formed is formed from a component material (e.g., a polymeric resin) to produce a film that exhibits suitable plastic deformability / ductility such that it can be locally plastically stretched (to a limited extent) in the x-y plane direction without failing or rupturing along discrete locations by passing through a deformation roller as described herein. The thermoplastic resins identified above either explicitly or by reference are considered potential non-limiting examples suitable for this purpose.

[0146] A suitable backsheet material may have a basis weight of from about 20 gsm to about 28 gsm, or from about 22 gsm to about 25 gsm. It has surprisingly been found that absorbent articles having a backsheet with a basis weight less than 20 gsm may be too thin in the plastically stretched region, resulting in a backsheet having a sheer appearance that is not desired by some consumers.

[0147] Machining

[0148] It has been recognized that machining at least the absorbent structure 40 or the absorbent structure with one or both of the topsheet 20 and the backsheet 30 in the manner described herein can provide a number of unexpected benefits.

[0149] The process referred to as "incremental stretching" involves passing a web through a nip between a pair of rollers having mating features such that discrete incremental portions of the web are stretched across lines coinciding with the features of the rollers. Non-limiting examples of incremental stretching methods and apparatus are disclosed in US 6,383,431. It has been recognized that this method can be applied not only to a single web layer but also to a composite web of multiple layers including components of the absorbent structure to obtain beneficial effects. For example, see Figures 8 to 13 , the mating rollers 302a, 302b may be provided with corresponding circumferential ridges 302d separated by circumferential grooves 302e. The rollers may be configured such that the ridges of one roller engage the grooves of the other roller to a desired engagement depth ED ( Figure 10 ). As the layered composite web 400 conveyed in the machine direction MD passes through the nip 302c between the engagement rollers, it will be stretched in the cross direction CD as it is forced to bend over the corresponding ridges 302d of each roller. If the engagement depth ED is appropriately adjusted, when the web 400 passes through the nip, one or more layer components of the composite web 400 may cause stretching along the machine direction line beyond the yield point of its plastic deformation or even fracture, thereby producing a deformed composite web 401. ( Figures 9 to 11 and Figure 13 The roller configurations reflected in Figure 11 and Figure 12This resulting less deformed or undeformed region 420 and more deformed region 410 of such potential CD deformation or breakage in the layer components of the fibrous web 401 are schematically depicted in. In Figure 10 and Figure 11 the depicted configuration, the direction of the tensile deformation DD is aligned or substantially parallel to the cross-direction CD.

[0150] See Figure 14 , in another configuration, the deformation rollers 306a, 306b can be configured to have mating / engaging ridges 306d and grooves 306e around their circumferential surfaces, and these ridges and grooves are parallel to their rotational axes. In this configuration, the rollers are similar to a pair of mating elongated spur gears, where their axes are oriented along the cross-direction CD. The fibrous web passing through the nip between these rollers will be stretched substantially along the machine direction above the corresponding "gear teeth", i.e., the ridges 306d, rather than being stretched along the cross-direction as described above and as Figure 11 and Figure 12 depicted.

[0151] Now see Figure 8 , it has been recognized that the composite fibrous web 400 including the absorbent structure can sequentially pass through the nips between two successive pairs of deformation rollers 302 and 306, so that the fibrous web is incrementally stretched and / or broken along two different directions (in this particular non-limiting example, the machine direction and the cross-direction) as described above. It has been recognized that after such deformation, compared to a similar structure that has not been so deformed, the absorbent structure (1) is significantly faster in acquiring and distributing fluids along and through it; (2) exhibits a relatively greater absorption capacity per unit weight of the absorbent material contained within the same time period; and (3) is significantly more flexible and pliable, making it more capable of bending around non-developable surfaces (i.e., body contours) and conforming to non-developable surfaces, and shifting as the body of the wearer moves (i.e., moving and shifting with the undergarment fabric as the body of the wearer moves). Without being bound by theory, it is believed that an absorbent article having one or more layer components so processed will be significantly more comfortable for the wearer / user of the product, and is more effective in intercepting body fluid exudates due to greater conformability to body features and faster acceptance, distribution, and absorption of fluids within its structure.

[0152] During the deformation process, the total x-y plane surface area of the absorbent structure can increase by up to about 35% or more. At the same time, the increased fluid collection and distribution speed ability and absorbency imparted to the article can enable the manufacturer to reduce or eliminate the inclusion of a specific amount of material and / or material layers (such as, for example, a separate collection / distribution layer), thereby resulting in material cost savings and enabling the manufacturer to provide a thinner, more comfortable, and more discrete absorbent article (such as, for example, a feminine hygiene pad) that performs equivalently to thicker competing / comparable products while being thinner, more discrete, and more comfortable for the user. Because the pad is stretched and permanently deformed in the longitudinal and lateral directions (along the x-y plane direction), the manufacturer may be able to reduce the total x-y plane dimensions of the absorbent structure and the entire pad prior to deformation, and through the deformation process, cause the reduced-size pad structure to assume the expanded final desired pad product size. The improved fluid collection speed and absorbency achieved via the deformation process enable more efficient use of the absorbent material, and thus, a relatively smaller amount of absorbent material is required per pad to provide the desired fluid collection and absorbency performance. Additionally, the deformation process described herein can eliminate the need for holes 43 (such as, for example, as Figure 2 shown) passing through the absorbent structure, as described above, thereby simplifying the manufacturing process.

[0153] In some configurations, the basis weight of the absorbent structure 40 can be from about 130 gsm to about 200 gsm.

[0154] It is believed that the enhanced liquid collection / distribution and absorbency can be attributed to the generation of increased and / or larger internal voids (from the fracture of the material) along the deformation lines within the absorbent structure. Further, when the composite fiber web 400 between the deformation rollers includes not only the absorbent structure but also one or both of the topsheet component and the backsheet component of the absorbent article, all of the layers can be deformed to different degrees according to their deformability or plastic extensibility, and all of the layers together as a composite can thereby be imparted with an expanded size in the x-y direction, increased biaxial extensibility, flexibility, and pliability.

[0155] This deformation in two directions is referred to herein as "bi-directional" deformation. Importantly, the bi-directional deformation composite fibrous web has an enhanced ability to bend around an irregularly contoured surface (such as the surface of a human body feature) and conform more closely to the irregularly curved surface. This degree of conformity is reflected in measurements that can be made using the conformity force measurement method described below. In some configurations, the absorbent article described herein may exhibit a conformity force of about 140 N / m to about 1500 N / m, or about 150 N / m to about 1000 N / m, or about 225 N / m to about 800 N / m. In contrast, current feminine hygiene pads exhibit a conformity force greater than 1600 N / m, and some are even greater than 5100 N / m. Without being limited by theory, it is believed that a product exhibiting a conformity force of about 140 N / m to about 1500 N / m is highly flexible and can move with the underwear during wear, which can result in a more comfortable and / or closer fit to the body.

[0156] See Figure 1 , Figures 4A to 4C , Figure 5 , Figure 11 and Figure 12 , the materials of the corresponding topsheet 20 and backsheet 30 can be selected and / or manufactured and / or formulated to have properties, and the engagement features and engagement depth of the deformation rollers can be constructed and adjusted such that, for example, when the topsheet and / or backsheet pass through the corresponding nip between the deformation rollers, the topsheet and / or the backsheet are only elastically stretched but not plastically stretched in the deformation zone 410, or alternatively plastically but do not fracture / fail / break. In combination, the materials / layers of the absorbent structure 40 can be selected and / or manufactured and / or formulated to have properties such that they will plastically stretch or even fracture (breakage / fracture) in an ordered manner and pattern in the region 410, reflecting the pattern of the ridges and grooves on the deformation rollers. Preferably, the topsheet and backsheet are selected and / or manufactured and / or formulated such that they will plastically (or permanently) stretch / deform in the regions 20s, 30s, substantially corresponding to the deformation lines 50, but do not break during the deformation process, while the absorbent structure material 40 is stretched and broken to create gaps 40s, also substantially corresponding to the deformation lines 50. In such a configuration, the combination of materials forming the absorbent article as a composite can be imparted with bi-directional extensibility and significantly enhanced flexibility and body conformity.

[0157] When the topsheet and backsheet are plastically stretched only to a greater x-y dimension without breaking, and one or more of the absorbent structural components / layers are stretched to breakage to form their discrete broken pieces 40p, a gap 40s substantially along the deformation line 50 between the broken edges of the sheet opens, thereby providing and opening a fluid passage through the absorbent structure and providing an increased surface area of the absorbent material to which fluid can be in contact for more rapid absorption compared to absorbent layer components that have not been so broken. A non-limiting example of an absorbent article in the form of a feminine hygiene pad that has undergone such biaxial deformation along the CD and MD is schematically depicted in Figure 1 FIG. Figure 5 FIG.

[0158] See Figure 1 and Figure 5 FIG. Figure 5 Absorbent article 10 includes sides 11, such as a first side, a second side, a third side, and a fourth side. Absorbent article 10 can include a first longitudinal side 12a extending in a direction substantially parallel to longitudinal axis 100 and a second longitudinal side 12b opposite the first longitudinal side 12a. Absorbent article 10 can also include a first lateral side 14a extending in a direction substantially parallel to lateral axis 200 and a second lateral side 14b opposite the first lateral side 14a. As Figure 5 shown, in some configurations, the absorbent article can include a first plurality of deformation lines 55 extending in a first direction substantially perpendicular to the first stretching direction 51a and a second plurality of deformation lines 56 extending in a second direction substantially perpendicular to the second stretching direction 51b. In some configurations, at least a portion of the first plurality of deformation lines 55 extends from a first side of absorbent article 10 to a second side of absorbent article 10. In some configurations, a portion of the first plurality of deformation lines 55 can extend from the first longitudinal side 12a to at least one of the second lateral side 14b and the second longitudinal side 12b. In some configurations, a portion of the second plurality of deformation lines 56 can extend from the first longitudinal side 12a to at least one of the first lateral side 14a and the second lateral side 12b.

[0159] See Figure 1 FIG. Figures 4B to 4D and Figure 5, the topsheet 20 and the backsheet 30 may each include sides 21, 31 respectively. For example, the topsheet 20 may include a first side, a second side, a third side, and a fourth side, and the backsheet 30 may include a first side, a second side, a third side, and a fourth side. The topsheet 20 may include a first longitudinal side 22a extending in a direction substantially parallel to the longitudinal axis 100 and a second longitudinal side 22b opposite the first longitudinal side 22a. The topsheet 20 may further include a first lateral side 24a extending in a direction substantially parallel to the lateral axis 200 and a second lateral side 24b opposite the first lateral side 24a. The backsheet 30 may include a first longitudinal side 32a extending in a direction substantially parallel to the longitudinal axis 100 and a second longitudinal side 32b opposite the first longitudinal side 32a. The backsheet 30 may further include a first lateral side 34a extending in a direction substantially parallel to the lateral axis 200 and a second lateral side 34b opposite the first lateral side 34a. In some configurations, the topsheet 20 and the backsheet 30 may each include plastic stretching zones 20s, 30s disposed substantially along a first plurality of deformation lines 55 and a second plurality of deformation lines 56. In some configurations, the topsheet 20 may include a plurality of plastic stretching zones 20s extending continuously across the entire topsheet 20. In some configurations, a portion of the plastic stretching zone 20s of the topsheet 20 may continuously extend from a first side of the topsheet 20 to a second side of the topsheet 20. For example, a portion of the plastic stretching zone 20s of the topsheet 20 may continuously extend from the first longitudinal side 22a to the second longitudinal side 22b. In some configurations, a portion of the plastic stretching zone 20s of the topsheet 20 may continuously extend from the first lateral side 24a to the second lateral side 24b. In some configurations, the backsheet 30 may include a plurality of plastic stretching zones 30s extending continuously across the entire backsheet 30. In some configurations, a portion of the plastic stretching zone 30s of the backsheet 30 may continuously extend from a first side of the backsheet 30 to a second side of the backsheet 30. For example, a portion of the plastic stretching zone 30s of the backsheet 30 may continuously extend from the first longitudinal side 32a to the second longitudinal side 32b. In some configurations, a portion of the plastic stretching zone 30s of the backsheet 30 may continuously extend from the first lateral side 34a to the second lateral side 34b.

[0160] For a feminine hygiene pad having an absorbent foam layer (e.g., a HIPE foam layer as described above) that forms part or substantially all of the absorbent structure 40, in order to provide the desired overall pad flexibility and effective fluid channels, it may be desirable for the deformation roller to be configured and sized to impart plastic deformation to the topsheet and backsheet and fracture of the absorbent foam layer such that the sheet 40p has an average x-y plane dimension across the entire absorbent structure of no greater than 15 mm, more preferably no greater than 10 mm, still more preferably no greater than 7 mm, and even more preferably no greater than 5 mm. (For the purposes of this document, the "x-y plane dimension" of the sheet 40p is its largest x-y plane dimension). In some configurations, the average x-y plane dimension of the foam sheet 40p can be from about 1.5 mm to about 15 mm, or from about 2 mm to about 5 mm. In some configurations, the foam sheet 40p can have a diamond x-y plane shape. In order to achieve the enhanced fluid collection and absorption performance and pad flexibility / flexibility envisioned herein, it may be desirable for the deformation roller to be configured and sized to impart plastic deformation to the topsheet and backsheet and fracture of the absorbent foam layer such that the gap 40s has an average x-y plane gap dimension across the entire absorbent structure greater than 0.1 mm, more preferably 0.3 mm, still more preferably 0.6 mm, and even more preferably 1 mm, or from 0.3 mm to about 1.2 mm, or any subrange thereof. (For the purposes of this document, the "x-y plane gap dimension" of the gap 40s is the x-y plane dimension of the space between adjacent sheets, measured along a direction perpendicular to the corresponding deformation line 50. Alternatively, for the same purpose, it may be desirable for the average x-y plane gap dimension to be proportional to the average thickness ("C") of the absorbent structure 40. Thus, it may be desirable for the gap 40s to have an average x-y plane gap dimension across the entire absorbent structure of at least (0.04×C), more preferably (0.12×C), still more preferably (0.24 xC), even more preferably (0.4 xC), or from (0.04×C) to (0.48×C), or any subrange thereof.

[0161] Figures 4A to 4D is schematically depicted the potential effects resulting from incrementally stretching a composite fibrous web including topsheet material, backsheet material, and absorbent structure material along the lateral direction of the pad depicted in Figure 1 The topsheet 20 can be along the deformation line 50 ( Figure 1)is plastically stretched in a relatively ordered configuration for 20 s, and the backsheet 30 can be plastically stretched along this deformation line for 30 s, where the topsheet material and / or the backsheet material has plastically deformed between the rolls and between the teeth or ridges in the nip of the deformation rolls along these deformation lines. The topsheet 20 and the backsheet 30 can each include a relatively less deformed or substantially undeformed region 20u, 30u disposed in the middle of the plastically stretched region. The absorbent structure 40 can be imparted with relatively ordered plastically strained deformation lines or preferably fracture lines to form gaps 40s. As Figure 4C depicted, in an alternative composite configuration, the absorbent structure 40 can include additional acquisition and / or distribution layers 41, 42, imparted with relatively ordered strain deformation lines or even fracture lines to form strain regions or even gaps 41s, 42s. In some examples, the additional layers 41, 42 can include nonwoven web materials in which portions of the absorbent foam precursor have been integrated into their fiber matrix and subsequently cured or polymerized into a foam structure, as shown, for example, in US2017 / 0119587; US2017 / 0119596; US2017 / 0119597; US2017 / 0119588; US2017 / 0119593; US2017 / 0119594; US2017 / 0119595; and US2017 / 0199598.

[0162] The size of the gap 40s between the foam sheets 40p in an article in which the absorbent foam as described herein forms the absorbent structure 40 or is a component of the absorbent structure can be adjusted via the configuration of the deformation rolls. A particularly effective aspect of such a configuration is the engagement depth ED of the corresponding mating / engaging deformation ridges 302d and grooves 302e (see Figure 10 ). A larger engagement depth ED will result in greater deformation of the topsheet and the backsheet and thus a relatively larger gap 40s, while a smaller engagement depth ED will result in less deformation of the topsheet and the backsheet and thus a relatively smaller gap 40s. Generally, an article having a gap 40s large enough to allow bending therethrough with minimal interference between the sheets 40p will be relatively more flexible and body conformable, while an article having a smaller gap 40s insufficient to allow bending therethrough without interference between the sheets 40p will be relatively less flexible and body conformable. This effect of the gap size GS is schematically shown in Figure 21A 、 Figure 21B 、 Figure 22A and Figure 22B 。 Figure 21ASchematically shows the deformation effect at a relatively small deformation roller engagement depth - relatively small deformation of the topsheet 20 and the backsheet 30, resulting in a relatively small size GS of the gap 40s between the sheets 40p. Thus, when the article is bent in the z-direction, as one of the topsheet 20 and the backsheet 30 is tensioned, adjacent sheets 40p begin to interfere at the interference position 40i. The cumulative effect of such interference between many sheets 40p at many gaps 40s within the article weakens the bending along the deformation line 50, and thereby reduces the overall flexibility and body conformity of the article. In contrast, Figure 22A Shows the deformation effect at a relatively large deformation roller engagement depth - relatively large deformation of the topsheet 20 and the backsheet 30, resulting in a relatively large size GS of the gap 40s between the sheets 40p. Thus, when bending the article along the z-direction, the sheets 40p are less likely to interfere during bending. Reducing the cumulative effect of such interference between many sheets 40p within the article makes the bending along the deformation line 50 easier, and thereby increases the flexibility and body conformity of the article. However, the deformation roller engagement depth must be limited such that the topsheet 20 and the backsheet 30 are not stretched to failure along the deformation line 50, and / or such that no potential negative consumer perception of the article quality occurs (e.g., the article is too flimsy or weak, or is damaged).

[0163] Now referring to Figure 5 , in some examples, the absorbent article may be provided with a deformation line 50 that is inclined with respect to the lateral axis 200 and the longitudinal axis 100. To achieve this result, in some examples, the composite web or assembled article may pass between machine direction loop rollers 302a, 302b (such as those shown in Figures 9 to 11 and Figure 13 ), which is achieved by feeding through these loop rollers along two different inclined directions relative to the machine direction in two consecutive steps. In other examples (not shown), the composite web or assembled article advancing along the machine direction may be continuously, intermittently fixed and compressed or stamped in the z-direction between pairs of flat deformation plates having ridges and grooves appropriately configured to incrementally stretch the web or article along the inclined direction. However, in order to incrementally stretch the composite web along two different directions inclined with respect to the continuously manufactured machine direction, such methods may be found to be cumbersome and inefficient compared to using spiral deformation rollers as described herein.

[0164] Alternatively, as shown in Figure 15A , Figure 15B , Figure 16A and Figure 16B shown, the deformation rollers used may have a configuration similar to a pair of mating / engaging spiral gears, helical gears, or worm gears (collectively referred to herein as deformation rollers having a "spiral" configuration with alternating grooves and ridges). As shown inFigure 15A , Figure 15B , Figure 16A and Figure 16B as reflected by (and also see Figure 5 and Figure 6 ), the first pair of such helically deforming rollers 307a, 307b can be configured to engage and have a selected helix angle γ1 when the article (or precursor combined fibrous web) passes through the nip therebetween, so as to impart to the article 10 a deformation line 50 that is substantially parallel to one of the deformation directions 50a, 50b by incrementally straining the article along one of the strain directions 51a, 51b. After passing through the nip between the rollers 307a, 307b, the article (or precursor combined fibrous web) can pass through a second nip between a second pair of deforming rollers 308a, 308b ( Figure 15B , Figure 16B ), which second pair of deforming rollers can also be configured to be helical and adapted to engage and be configured to have a selected helix angle γ2, and when the article (or precursor combined fibrous web) passes through the nip therebetween, impart to the article 10 a deformation line 50 that is substantially parallel to the other of the deformation directions 50a, 50b by incrementally straining the article along the other of the strain directions 51a, 51b.

[0165] With such a configuration, the deformation of the fibrous web passing through the nip therebetween will occur along the deformation line 50, which is inclined with respect to the MD and CD on the fibrous web, with respect to the machine direction and the cross direction, along the deformation angle imparted by the helix angle of the helical ridges 307d, 308d and the engaging helical grooves 307e, 308e along the outer circumference or radial outer edge of the rollers. Two consecutive pairs of such helically deforming rollers having different or opposite orientations of helix angles can be arranged along the processing line to continuously strain and deform the composite fibrous web in two different directions, and thus impart biaxial deformation to the article or its precursor fibrous web, e.g., as Figure 5 shown. It may be preferred that the helix angles of consecutive pairs of helically deforming rollers are selected such that the angles α and β formed at the intersection of the resulting deformation line 50 with the longitudinal axis of the article are substantially equal, so as to impart to the article tensile / elongation / conformability characteristics and an appearance that is substantially symmetric about and / or aligned with the longitudinal axis.

[0166] Return to reference Figure 5 and Figure 6, the helically deformed roller can be configured to impart biaxial strain and deformation along strain directions 51a, 51b that are inclined with respect to the longitudinal / x and lateral / y directions of the absorbent article 10, such as a feminine hygiene pad. For feminine hygiene pads, it has been recognized that a biaxially deformed pad having deformation lines 50 parallel to deformation direction lines 50a, 50b, which deformation direction lines are substantially perpendicular to the strain directions 51a, 51b, which strain directions are oriented at angles α and β with respect to the lateral direction, respectively, is more likely to shift and conform well to the body movements (e.g., walking) of the wearer when adhered to the inner surface of the crotch region of the wearer's undergarment. Accordingly, it is preferred that the deformation direction lines 50a, 50b are each about 5 degrees to about 85 degrees, more preferably about 15 degrees to about 70 degrees, and even more preferably about 30 degrees to about 60 degrees with respect to the longitudinal axis of the article. All sub-ranges within these ranges are contemplated herein.

[0167] When the wearer moves around, the pad adhered to the inner surface of the wearer's undergarment is better able to shift and move with the fabric of the undergarment. This results in a significant improvement in wearer comfort.

[0168] It has also been recognized that such strain directions that are inclined with respect to the machine direction of movement of the web through the nip, as compared to strains imparted by rollers such as those shown in Figures 9 to 14 are less likely to damage the nonwoven web material. This is believed to be a synergistic benefit not previously recognized and is due to the typical machine direction bias of the fibers in nonwoven web materials (especially spunbond nonwoven web materials). Spunbond nonwoven web materials typically have a machine direction bias due to the manner in which they are manufactured, i.e., by depositing spun fibers onto a forming belt moving in the machine direction. (In this document, with respect to the fibers forming the nonwoven web, "machine direction bias" means that most fibers (such as those located in the web and that are not stretched) have a length such that the machine direction vector component is greater than their cross-direction vector component). Due to the manner in which the article 10 and its component web materials are typically manufactured, the nonwoven web components typically have a machine direction bias that is consistent with the longitudinal (y) direction of the article. As shown in Figure 5 and Figure 6 , when the deformation directions 51a, 51b are inclined with respect to the machine direction / longitudinal direction, the fibers are less likely to be directly pulled along their length in the machine direction or separated in the cross direction, and thus, are less likely to be stretched beyond their limits and broken along their length and less likely to be separated in the cross direction, which could result in undesirable changes or damage to the structural integrity and quality of the web material.

[0169] It is contemplated that a pair of forming rolls can be configured to impart biaxial deformation to the composite fibrous web in a single pass through the nip, i.e., where the rolls are characterized to simultaneously cause incremental stretching of the composite fibrous web in two different directions, the two different directions including directions parallel and orthogonal to the machine direction or inclined to the machine direction, as described above. However, it is preferred to impart stretching continuously along two different directions via two pairs of successive forming rolls. This can enable better control of the stretching process along each direction and reduce the chance of unwanted fracture lines or fracture paths in the absorbent structure or damage to components of the web.

[0170] It is also contemplated that one or more pairs of forming rolls can be configured to deform only discrete regions or zones of the composite fibrous web while leaving adjacent regions or zones undeformed. In Figure 7 the non-limiting example depicted, an article in the form of a feminine hygiene pad 10 can be biaxially deformed only in defined zones or regions (in the non-limiting example shown in Figure 7 , the central region is shown with inclined deformation lines 50), while the remaining zones remain undeformed. Biaxial deformation can be imparted along directions 50a, 50b and 51a, 51b, angles α and β, as described above. In Figure 7 the example shown, the central region is deformed and the side regions including the wings 15 remain undeformed. The deformed regions and the regions to be kept undeformed can be configured for various effects.

[0171] However, it may be preferred to biaxially deform the entire x-y area of the layered material forming the article 10 (as shown in Figure 1 and Figure 5 ) without breaks or discontinuities in the biaxial deformation pattern, such as in Figure 7 where one or more portions have not been deformed. This is because discontinuities or breaks in the biaxial deformation pattern can result in discontinuities in the flexibility and pliability imparted by the deformation, thereby impairing the ability of the article 10 to closely conform to the wearer's body features and to move with the fabric of the wearer's undergarment and / or the wearer's body.

[0172] Referring again to Figure 1 , Figures 4A to 4D , Figure 19 and Figure 20 , as described above, the biaxial deformation process can be configured to break the material of the absorbent structure 40 into a plurality of discrete sheets 40p in an orderly manner along the deformation lines 50. For example, in the case where the material of the structure 40 includes a layer of material that is relatively inelastic or brittle under tension (such as, for example, an absorbent foam of a suitable composition as described herein), a properly configured process will break the structure 40 in an orderly manner to produce discrete sheets 40p of generally uniform size separated by gaps 40s that are delineated along the deformation lines 50.Figure 19 and Figure 20 represents a photograph of an actual prototype example of the absorbent article 10, depicting such deformation lines 50, sheet 40p, and gap 40s.

[0173] To prevent the discrete sheets 40p from shifting and misaligning within the structure after breakage (i.e., to keep them substantially in their relative pre-break positions), a structure for holding them in place within the encapsulating space between the topsheet and the backsheet may be desirable. To this end, deposits 45 of a suitable adhesive / glue material may be provided at positions between one or both of the wearer-facing interface and the out-facing interface between the absorbent structure 40 and the topsheet and backsheet, or at positions between the absorbent structure and other interlayer components (such as, for example, a distribution layer). In particular for the adhesive that may be provided between the wearer-facing surface of the absorbent structure 40 and the topsheet 20, the deposit 45 may be applied via controlled spraying in the manner described above so as not to create an occlusive adhesive film, but rather to bond the corresponding materials together at discrete locations corresponding to the deposited glue droplets, while avoiding creating a fluid barrier and leaving the absorbent structure 40 effectively unoccluded on its wearer-facing surface. However, in some configurations, it may be considered suitable or even preferred that the application of the adhesive between the out-facing surface of the absorbent structure 40 and the backsheet is more extensive, continuous, or even substantially film-like, since blockage (such as, for example, a layer of absorbent foam) at or on the out-facing surface of the absorbent structure may be of less concern. And such a more extensive or continuous application may be better suited to holding the broken sheets 40p of the absorbent structure 40 in place after deformation as described herein. Thus, adhesive deposits may be provided at both the upper and lower surfaces of the absorbent structure 40 or its layer components to provide a more cohesive overall pad structure and minimize the opportunity for the sheets 40p to shift and misalign within the structure.

[0174] Preferably, the adhesive deposits are applied across a majority of the x-y plane surface area of one or both of the wearer-facing surface and the clothing-facing surface of the absorbent structure 40. To reduce the chance of hardening effects due to the application of the adhesive / glue between the respective lower adjacent layer / upper adjacent layer of the pad, it may be desirable for the selected adhesive / glue material to have an elastic and / or resilient formulation. In some configurations, the adhesive may be a pressure-sensitive adhesive having a relatively long open time. A suitable adhesive may have a relatively high elastic modulus (G') to withstand the forces applied during machining when the material is stretched. An adhesive utilizing styrene / isoprene / styrene (SIS) structural units may be preferred. A suitable example may be an adhesive named H2031-C5X, which is a product of Bostik, a division or subsidiary of Arkema in Colombes, France.

[0175] In some configurations, the adhesive may be disposed between the wearer-facing surface of the absorbent structure 40 and the topsheet, as Figures 3A to 3D shown and described. In some configurations, the adhesive may be disposed between the wearer-facing surface of the absorbent structure 40 and the topsheet at a basis weight of from about 15 gsm to about 35 gsm, or from about 18 gsm to about 32 gsm, or from about 20 gsm to about 30 gsm, specifically listing these ranges and all values within any resulting range. In some configurations, the adhesive may be disposed between the outward-facing surface of the absorbent structure 40 and the backsheet at a basis weight of from about 15 gsm to about 35 gsm, or from about 18 gsm to about 32 gsm, or from about 20 gsm to about 30 gsm, specifically listing these ranges and all values within any resulting range. Consumer testing has surprisingly shown that when the basis weight of the adhesive between the topsheet and the absorbent structure and / or between the backsheet and the absorbent structure is less than 15 gsm, respectively, the foam sheet may shift and misalign within the absorbent article during wear, resulting in a non-uniform distribution of the absorbent material, which may negatively affect comfort and / or fluid handling performance.

[0176] It should be understood that the absorbent structure described above may be suitable not only for use as a feminine hygiene pad, but also for use as an incontinence pad or an absorbent insert for use within underwear, or even for use as a structural sub-component of a disposable menstrual underwear or a disposable adult incontinence underwear for use / worn by men or women.

[0177] In some configurations, the absorbent article structure manufactured as described herein may have a porous / liquid-permeable nonwoven fibrous web material (such as a spunbond fibrous web material) that replaces one or both of the materials of the topsheet 20 and the backsheet 30 described above, positioned and disposed similarly such that fluid can freely flow into and out of the structure at both its upper and lower surfaces. The structure may be machined as described above to obtain similar effects and benefits as described above. Such an absorbent article structure may then be incorporated as a layer component of, for example, an absorbent core structure within an absorbent article, such as a disposable baby / child diaper, a disposable child training pant, a disposable feminine hygiene pad, a disposable incontinence pad, a disposable menstrual underwear, or a disposable incontinence underwear.

[0178] Test / measurement method

[0179] Capillary work potential via pore volume distribution

[0180] The pore volume distribution determines the estimated porosity of the effective pores within a porous sample by measuring the fluid movement into and out of the sample when a step-controlled pressure differential is applied to the sample in a sample chamber. The incremental and cumulative amounts of fluid absorbed / emitted by the porous sample at each pressure are then determined. Subsequently, the work done by the porous sample normalized by the area of the sample is calculated as the capillary work potential.

[0181] Method principle

[0182] For a uniform cylindrical pore, the radius of the pore is related to the pressure difference required to fill or empty the pore by the following formula:

[0183] Pressure difference = [2γ cos Θ)] / r

[0184] where γ = the surface tension of the liquid, Θ = the contact angle, and r = the pore radius.

[0185] The pores contained in natural and artificial porous materials are usually referred to by terms such as voids, pores, or ducts, and these pores are generally not completely cylindrical or completely uniform. However, the above formula can be used to relate the pressure difference to the effective pore radius, and the effective pore radius distribution in the porous material can be characterized by monitoring the variation of the movement of liquid flowing into or out of the material with the pressure difference. (Since the use of the effective pore radius approximates non-uniform pores as uniform pores), the results obtained by this general method may not exactly agree with the measurements of void sizes obtained by other methods (such as microscopy).)

[0186] The pore volume distribution method utilizes the above principle and applies the method to practice using equipment and methods as described in "Liquid Porosimetry: New Methodologies and Applications" published by B. Miller and I. Tyomkin in The Journal of Colloid and Interface Science (1994), Volume 162, pages 163 - 170, which is incorporated herein by reference. The method relies on measuring the incremental volume of liquid flowing into or out of a porous sample as the air pressure differential changes between ambient ("laboratory") air pressure and a slightly elevated air pressure (positive pressure differential) around the sample in the sample test chamber. The sample is introduced into a dry sample chamber, and the sample chamber is controlled at a positive pressure differential (relative to the laboratory), which is sufficient to prevent the absorption of fluid into the sample after the fluid bridge is opened. After opening the fluid bridge, the air pressure differential is reduced to 0 in steps, and during this process, a subset of the pores within the sample collect liquid according to their effective pore radius. After reaching the minimum pressure differential at which the fluid mass within the sample is at a maximum, the pressure differential is gradually increased again towards the starting pressure, and the liquid is expelled from the sample. The absorption portion of the step sequence begins at the maximum pressure differential (minimum corresponding effective pore radius) and ends at the minimum pressure differential (maximum corresponding effective pore radius). The discharge portion of the sequence begins at the minimum pressure differential and ends at the maximum pressure differential. After emptying the entire absorption / discharge sequence while correcting for any fluid movement for each specific pressure step measured on the chamber, the fluid absorption amount (mg) and the cumulative volume (mm 3 / mg) of the sample at each pressure differential are determined in the method.

[0187] Sample conditioning and sample preparation

[0188] The pore volume distribution method is performed on samples that have been conditioned in a chamber maintained at a temperature of 23°C ± 2.0°C and a relative humidity of 50% ± 2% for at least 2 hours, and all tests are conducted under the same environmental conditions in such a conditioning chamber. Any damaged products or samples with defects such as wrinkles, tears, holes, etc. are not tested. For the purposes of the present invention, samples conditioned as described herein are considered to be dry. Determine which face of the sample is intended to face the wearer in use, and then cut it into a length of 55 mm × width of 55 mm. Measure the mass of the sample and record it to an accuracy of 0.1 mg. Three samples are measured for any given material being tested, and the results of these three parallel determinations are averaged to give the final reported value.

[0189] Equipment

[0190] The apparatus suitable for this method is described in "Liquid Porosimetry: New Methodology and Applications" by B. Miller and I. Tyomkin, published in The Journal of Colloid and Interface Science (1994), Volume 162, pages 163 - 170. Additionally, any pressure control scheme capable of controlling the sample chamber pressure between a differential pressure of 0 mm H 2 0 and 1098 mm H 2 0 can be used in place of the pressure control subsystem described in this reference. An example of a suitable integrated instrument and software is the TRI / Autopore (Textile Research Institute (TRI) / Princeton Inc. of Princeton, NJ, USA). The TRI / Autopore is an automated computer - controlled instrument for determining the pore volume distribution in porous materials (e.g., the volume of pores of different sizes in the range of 5 µm to 1200 µm effective pore radius). Computer programs such as Autopore Instrument Software Version 2000.1 or 2003.1 / 2005.1 or 2006.2; or Data Processing Software Version 2000.1 (available from TRI Princeton Inc.), and spreadsheet programs can be used to capture and analyze the measured data.

[0191] A schematic of the properly equipped apparatus is shown in Figure 18 The apparatus consists of a balancer 800 with a fluid reservoir 802 that is in direct fluid communication with a sample 805 residing in a sealed air - pressurized sample chamber 810. The fluid communication between the reservoir 802 and the sample chamber 810 is controlled by a valve 815. A confining pressure of 0.25 psi is applied to the test sample using weights 803 placed on top of a resin glass plate 804 (55 mm long × 55 mm wide) to ensure good contact between the sample and the fluid - saturated membrane 806 throughout the test. The membrane 806 (90 mm diameter, 150 µm thick, 1.2 µm pore size; mixed cellulose ester filter RAWP09024; purchased from Millipore Corporation of Bedford, MA) is attached to a macroporous fritted disc 807 (Monel plate, 90 mm diameter, 60 mm thick; purchased from Mott Corporation, Farmington, CT, or equivalent) as follows. Using Krylon as an adhesive ®A spray paint (Gloss White Spray Paint #1501; purchased from FilmTools, or equivalent) adheres the membrane 806 to the frit 807. The prepared membrane / frit assembly is dried before use.

[0192] To prepare the equipment for testing, the inner base 812 of the sample chamber 810 is filled with the test fluid. The test fluid is degassed with a 0.9% saline solution prepared by adding 9.0 g of reagent-grade NaCl per 1 L of deionized water (liquid density is 1.01 g / cm 3 , surface tension γ is 72.3 + 1 mN / m, contact angle cos Θ = 0.37). The membrane / frit assembly is placed on the inner base 812 of the sample chamber 810 with the membrane 806 facing up, and it is fixed in place with the lock ring 809. The reservoir 802 and the connecting tube 816 are filled with the test fluid. The valve 815 is opened and it is ensured that no air bubbles are trapped in the connecting tube or in the holes within the membrane / frit assembly. Using the legs 811 of the sample chamber 810, the sample chamber is leveled as needed and the height of the sample chamber (and / or the amount of fluid in the reservoir 802) is adjusted so that the top surface of the membrane 806 is in the same horizontal plane as the top surface of the fluid in the reservoir 802.

[0193] The system is programmed to implement a series of stepwise pressure differences (in mm H 2 0) as follows: 1098, 549, 366, 275, 220, 183, 137, 110, 92, 78, 69, 61, 55, 50, 46, 42, 39, 37, 34, 32, 31, 29, 27, 24, 22, 20, 18, 14, 9.2, 6.9, 5.5, 4.6, 5.5, 6.9, 9.2, 14, 18, 20, 22, 24, 27, 29, 31, 32, 34, 37, 39, 42, 46, 50, 55, 61, 69, 78, 92, 110, 137, 183, 220, 275, 366, 549, 1098. These pressures are related to effective pore radii from 5 µm (1098 mm H 2 0) to 1200 µm (4.6 mm H 2 0). The criterion for moving from one pressure step to the next is that the absorption / emission of the fluid measured at the balancer 800 is less than 10 mg / min for 15 seconds.

[0194] Method procedure

[0195] Check the system for leaks and ensure that the maximum test pressure can be achieved as follows. With the liquid valve 815 open, place the top 808 of the sample chamber 810 in position and seal the chamber. Apply sufficient air pressure to the chamber 810 (via the connector 814) to achieve a pressure differential of 1098 mm H 2 O (effective pore radius of 5 µm). Close the liquid valve 815, then open the sample chamber. Place the sample 805 (wearer facing down) directly onto the membrane 806, then center the cover plate 804 and the restraint weight 803 over the sample. Replace the top 808 and reseal the sample chamber 810. Open the liquid valve 815 to allow fluid to move between the liquid reservoir 802 and the sample, and initiate the test to proceed through a pre-specified sequence of pressure differentials. Record the amount of fluid absorbed (or discharged) by the sample at each pressure step over the entire sequence as the absorption amount, accurate to 0.1 mg.

[0196] In the absence of the sample 805, cover plate 804, or restraint weight 803 on the membrane / fritting assembly, perform an independent "blank" measurement on the empty sample chamber by following the same method procedure (the same sequence of pressure differential steps). Record any fluid movement (mg) observed at each pressure step. Correct the fluid absorption data of the sample for any fluid movement associated with the empty sample chamber by subtracting the fluid absorption value of this "blank" measurement from the corresponding value in the sample measurement, and record as the blank-corrected sample absorption amount, accurate to 0.1 mg.

[0197] Determination of capillary pressure, cumulative volume and capillary work potential

[0198] The sample saturation percentage at each pressure step for both the absorption and discharge portions of the test sequence can be calculated by dividing the maximum blank-corrected sample absorption amount (mg) by the blank-corrected sample absorption amount (mg), then multiplying by 100. Based on the data collected over the entire sequence, a person of ordinary skill in the art can then determine the saturation percentage at any given capillary absorption pressure (CAP) or capillary desorption (discharge) pressure (CDP). For any specified saturation percentage, report the CAP and CDP, accurate to 0.1 mm H 2 O.

[0199] Calculate the cumulative volume at each pressure step using the following formula:

[0200] Cumulative volume (mm 3 / mg) = blank-corrected sample absorption amount (mg) / fluid density (g / cm 3 ) / sample mass (mg)

[0201] The capillary work potential (CWP) is the work done by the sample normalized by the sample area. The trapezoidal rule is used to integrate the i-th pressure as a function of the cumulative volume over n data points for the absorption and emission portions of the cycle.

[0202]

[0203] where

[0204] m w = sample mass (mg)

[0205] CV = cumulative volume (m 3 / mg)

[0206] P = barometric pressure (Pa)

[0207] A w = sample area on one side (m 2 )

[0208] Report CWP, CWPA, and CWPD to the nearest 0.1 mJ / m 2 , where CWPA represents the absorption portion of the pressure sequence and CWPD represents the emission portion of the pressure sequence.

[0209] Thickness measurement

[0210] Measure the thickness (caliper, thickness) of test samples of nonwoven webs, laminates, and foam sheet materials as the distance between a reference platform on which the sample is placed and a pressure foot that applies a specified amount of pressure to the sample over a specified amount of time. All measurements are made in a laboratory maintained at 23°C ± 2°C and 50% ± 2% relative humidity, and the test samples are conditioned in this environment for at least 2 hours before testing.

[0211] Measure the thickness with a manually operated micrometer equipped with a pressure foot capable of applying a steady pressure of 2.0 kPa ± 0.01 kPa to the test sample. The manually operated micrometer is a deadweight instrument with a reading accuracy of 0.001 mm. A suitable instrument is the Mitutoyo Series 543 ID-C Digimatic from VWR International, or equivalent. The pressure foot is a flat circular movable surface with a diameter smaller than the test sample and capable of applying the required pressure. A suitable pressure foot has a diameter of 25.4 mm, but smaller or larger pressure feet can be used depending on the size of the sample being measured. The test sample is supported by a horizontal flat reference platform that is larger than and parallel to the surface of the pressure foot. The system is calibrated and operated according to the manufacturer's instructions.

[0212] If necessary, a test sample is obtained by removing it from the absorbent article. When cutting out the test sample from the absorbent article, care is taken not to cause any contamination or dimensional distortion to the test sample layer. The test sample is taken from an area without creases or wrinkles and must be larger than the pressure foot.

[0213] To measure the thickness, first zero the micrometer relative to a horizontal flat reference platform. Place the test sample on the platform with the test location centered under the pressure foot. Gently lower the pressure foot at a descent rate of 3.0 mm ± 1.0 mm per second until all the pressure is applied to the test sample. Wait for 5 seconds and then record the thickness of the test sample to an accuracy of 0.01 mm. In a similar manner, repeat a total of five replicate test samples. Calculate the arithmetic mean of all thickness measurements and report as "thickness" to an accuracy of 0.01 mm.

[0214] Conforming force measurement method

[0215] Measurements made using this conformability force measurement method reflect the degree to which a composite fibrous web material (i.e., a combination, assembly, or laminate of fibrous web materials) will resist bending and stretching around an irregular surface. A composite fibrous web material that is bi-axially extensible will bend and stretch more easily around an irregular surface compared to a comparable composite that is not bi-axially extensible. In this method, the irregular surface is a spherical ball with a diameter of 25.4 mm.

[0216] The conformability force measurement method is performed on a tensile testing machine at a constant rate using a custom fixture and a load cell of appropriate capacity (a suitable instrument is the MTS Insight tensile testing machine operating under TestSuite software, MTS Systems Corp, Eden Prairie, MN, or equivalent). All tests are conducted in a laboratory controlled at 23 °C ± 2 °C and 50% ± 2% relative humidity.

[0217] See Figure 17, the bottom fixture 1100 is a pneumatic clamping system for horizontally fixing the specimen 1117 for testing. The fixture consists of a box 1103 made of 6.4 mm Plexiglass, which has a top 1101 and a bottom 1102 both made of 9.5 mm thick aluminum plates. The bottom 1102 is attached to the bottom mount of the tensile testing machine via an adapter 1104 and a lock ring 1105, and the lock ring is used to fix the fixture orthogonally to the mount of the tensile testing machine. Inside the box, a movable plate 1106 made of 9.5 mm thick aluminum is attached to two pneumatic cylinders 1107 and 1108 for raising and lowering the test specimen 1117. Rubber washers 1113 are fixed on the bottom side of the top plate 1101, and matching rubber washers 1114 are fixed to the top of the movable plate 1106. A circular vertical orifice 1115 with a diameter of 50.1 mm passes through the longitudinal and lateral centers of the top plate 1101 and the washer 1113. A corresponding circular orifice 1116 with a diameter of 50.1 mm is vertically aligned with the orifice 1115 and passes through the movable plate 1106 and the washer 1114. Pressurized air 1110 is supplied to a switch 1109, which is fluidly connected to the cylinders 1107 and 1108 via pipes 1111 and 1112 and is used to raise and lower the movable plate 1106. The air pressure is sufficient to firmly hold the sample without slipping for testing.

[0218] The upper fixture includes a cylindrical plunger 1003 terminating in a ball 1004 with a diameter of 25.4 mm. The plunger has an adapter 1001 compatible with the mount on the load sensor, which can fix the plunger orthogonally to the top plate 1101 of the bottom fixture. When the fixture is assembled with the testing machine, the ball 1004 is vertically centered above the orifices 1115 and 1116, and the center of the ball travels along a vertical path coinciding with the vertical axis of the orifices. The gauge length between the bottom surface of the ball 1004 and the bottom surface of the washer 1113 is set to 10 mm.

[0219] Program the instrument into the compression mode. Lower the crosshead to the specified engagement distance at a rate of 500 mm / minute and return the crosshead to its original position. Record the data from the force and distance channels at a rate of 100 Hz during the downward stroke. Run the measurement cycle on each sample for three specified crosshead distances: 15 mm (i.e., 5 mm engagement), 20 mm (i.e., 10 mm engagement), and 25 mm (i.e., 15 mm engagement).

[0220] Test specimens are conditioned in a laboratory controlled at 23 °C ± 2 °C and 50% ± 2% relative humidity. Place the specimen on a flat workbench with the top surface facing up. Identify the longitudinal axis of the specimen. Measure 45 mm down from the top edge of the absorbent structure along the longitudinal axis and mark with a dot. This is the center of the measurement site. Remove the release paper (or adhesive cover sheet) from the specimen, if present. Place the marked point at the center within the opening of the lower plate. Before securing the specimen between gaskets 1113, 1114, the specimen should be gently tensioned with approximately equal tension applied along two perpendicular directions, just enough to eliminate sagging over the opening 1116. After tensioning the specimen, activate switch 1109 to allow air to enter cylinders 1107, 1108 and thereby raise the movable plate 1106 to secure the specimen between gaskets 1113, 1114. Zero the force and crosshead travel and start the program. After testing, lower the movable plate and remove the specimen before analyzing the next specimen. Test seven (7) replicate specimens at each of three crosshead distances.

[0221] For each test run, plot a graph of force (N) versus displacement (mm). Read the peak force (N) from the graph and record it precisely to 0.01 N. Calculate the conforming force as the maximum slope of the curve using a line segment that is at least 20% of the maximum force and record it precisely to 0.1 N / m. Record the conforming force as the average obtained from the seven replicate specimens, precise to 1 N / m, when the specimen is displaced 5 mm from its starting position (i.e., after the ball first contacts the specimen and it moves down a maximum of 5 mm).

[0222] High-speed tensile test

[0223] High speed tensile testing is used to measure the tensile strength of a material specimen at a relatively high strain rate. The method uses a suitable tensile testing machine such as an MTS 810 from MTS Systems Corp., Eden Prairie, Minnesota or equivalent, equipped with a servo-hydraulic actuator that is capable of accelerating at a speed greater than 1 m / s after a crosshead displacement of 5 mm and at a speed of at least approximately 1.5 m / s after a crosshead displacement of 10 mm. The tensile testing machine is equipped with a 50 lbf load cell (part 9712B50 from Kistler North America, Amherst, New York or equivalent) and a signal conditioner with a dual-mode amplifier (part 5010 from Kistler North America or equivalent).

[0224] Figure 23It is a cross-sectional view of the single-line contact gripper 2700 used in this test. The wire gripper 2700 is selected to provide a well-defined gauge length and avoid inappropriate slippage of the specimen. The specimen is positioned such that it has minimal slack. The apex 2707 of the gripper 2700 is polished to provide good gauge definition while avoiding damage or cutting of the specimen. A portion of the gripper 2700 may be configured to include a material 2705 that reduces the tendency of the specimen to slip. Figure 24 A pair of opposing wire contact grippers 2700 suitable for this test is shown. Optionally, a pair of grippers with different specific designs but having the same functions as those described above (i.e., capable of facilitating a well-defined 3 mm gauge length, no inappropriate slippage, and at least as wide as the specimen being analyzed) is used.

[0225] For the nonwoven samples of interest, cut five similar specimens with dimensions of 50.8 mm wide × 15 mm long. The short dimension of each specimen is parallel to the machine direction of the nonwoven material. If the specimen is extracted from a finished absorbent article, the short dimension of the specimen is oriented parallel to the longitudinal axis of the absorbent article. Move the wire contact grippers to a gripper spacing of 3.0 mm (i.e., the distance between the contact lines between the specimen and the gripper surfaces). Mount the specimen in the wire contact grippers, and when mounted in the grippers, use a thin tape strip to help keep the specimen straight and flat. (If used, the tape must be kept behind the gripping line so that it does not interfere with the specimen gauge during the test). Move the wire contact grippers closer together to put as much slack as possible into the film specimen without the wire contact grippers interfering with each other. Select the actuator motion such that the specimen experiences a relative gripping speed of approximately 1 m / s at engineering strain 1 and approximately 1.5 m / s at engineering strain 4. Typically, during the test, one of the wire contact grippers in the pair of wire contact grippers remains stationary and the opposing wire contact gripper moves, but forms in which both wire contact grippers move are also contemplated herein.

[0226] Use a Nicolet Integra Model 10, 4-channel 1 Ms / s, 12-bit digital oscilloscope to record the force and actuator displacement data generated during the test, with the data acquisition frequency set to 50 kHz. The resulting data is presented as force (measured in Newtons) versus engineering strain. Engineering strain ( ) is dimensionless and is defined as

[0227]

[0228] where:

[0229] L 0 is the gauge length (i.e., the distance between the gripper contact lines when the undeformed specimen is mounted in the grippers). (L in this embodiment0 is 3.0 mm).

[0230] L is the grip position, the distance between the grip contact lines during the tensile test.

[0231] And z is the displacement, defined as z = L - L 0 .

[0232] Figure 25 Figure 2900 shows a suitable exemplary graph with two curves 2910 and 2920. The first curve 2910 shows a graph of actuator speed (i.e., the relative speed at which one grip moves away from the other grip) versus engineering strain. Arrow 2911 points to the vertical axis on the right side for graph 2910. The second curve 2920 shows a graph of force versus engineering strain and uses the vertical axis on the left side, as indicated by arrow 2921. Identify the point of maximum force in the force-versus-engineering-strain graph. Move towards higher engineering strain, then identify the first point where the force drops to equal or less than 90% of the maximum force value, and define the engineering strain at that point as the ductility parameter of the specimen and record it precisely to 0.01. (The area where this point is located is indicated by arrow 2930).

[0233] The arithmetic mean of the five ductility parameter values determined for each of five similar specimens is reported as the ductility parameter of the material sample, precise to 0.01.

[0234] Melting enthalpy and crystallinity test

[0235] The melt enthalpy and crystallinity tests are used to determine the melt enthalpy and crystallinity percentage parameters. The melt enthalpy and crystallinity tests include performing ASTM E793-06 and the following additional instructions. Specimens are punched from the sample nonwoven web. The mass of the specimen is 3 ± 2 mg, and the mass of the specimen is recorded, precise to 0.01 mg. (If multiple layers are needed to achieve the required sample mass, the sample nonwoven web is folded so that multiple layers of the same nonwoven web are punched simultaneously to produce the specimen). Dry nitrogen is used as the purge gas in a differential scanning calorimeter (DSC). The test temperature range is -90 °C to 200 °C. The heating rate in the DSC is 20 °C / minute, and the cooling rate is 20 °C / minute. The melting peak temperature is determined as described in §11 of ASTM E793-06. The mass-normalized melt enthalpy is calculated as specified in §11 of ASTM E793-06 and reported as the melt enthalpy parameter in joules per gram (J / g) (ΔH m ), precise to 0.01 J / g.

[0236] Based on the enthalpy of the melting parameter, the percentage of crystallinity is determined using the following equation:

[0237]

[0238] wherein is the mass-normalized melting parameter enthalpy,

[0239] is the mass-normalized melting enthalpy of 100% crystalline polypropylene (taken herein as 207 J / g), and

[0240] is the weight fraction of polypropylene.

[0241] The percent crystallinity is reported as an integer value accurate to the nearest percent.

[0242] In view of the foregoing description, the following non-limiting examples are contemplated herein:

[0243] A1. An absorbent article (10) comprising: a liquid-permeable topsheet (20); a liquid-impermeable backsheet (30); an absorbent structure (40) disposed between the topsheet and the backsheet, the absorbent article having a longitudinal axis (100) and a lateral axis (200);

[0244] wherein the absorbent article has been incrementally stretched along at least a first stretching direction (51a) and a second stretching direction (51b) different from the first stretching direction such that:

[0245] the topsheet and the backsheet each have permanent or plastic stretch deformation zones (20s, 30s) disposed substantially along two sets of corresponding deformation lines (50), a first set of deformation lines (50) being substantially perpendicular to the first stretching direction (51a), and a second set of deformation lines (50) being substantially perpendicular to the second stretching direction (51b); and

[0246] the topsheet and the backsheet each have zones (20u, 30u) that are relatively less deformed or substantially undeformed between the deformation lines (50).

[0247] A2. The article according to embodiment A1, wherein the two sets of deformation lines (50) form respective angles (α) and (β) with respect to the longitudinal axis (100), each angle being from 5 degrees to 85 degrees, more preferably from 15 degrees to 70 degrees, and even more preferably from 30 degrees to 60 degrees, and any sub-range within these ranges.

[0248] Article according to embodiment A1 or A2, wherein the absorbent structure comprises a layer of absorbent foam material, preferably HIPE foam material, and the absorbent foam material layer is substantially broken along the deformation line (50) into a plurality of discrete sheets (40p), wherein all or a subset of the discrete sheets (40p) are separated from adjacent sheets by gaps (40s).

[0249] Article according to embodiment A3, wherein the discrete sheets (40p) have an average x-y plane dimension across the entire absorbent structure of no greater than 15 mm, more preferably no greater than 10 mm, still more preferably no greater than 7 mm, and even more preferably no greater than 5 mm.

[0250] Article according to any one of embodiments A1 to A4, wherein the absorbent structure has an average thickness (C) of at least (0.04×C), more preferably (0.12×C), still more preferably (0.24×C), and even more preferably (0.4×C), or (0.04×C) to (0.48×C), or any sub-range thereof, and the gaps (40s) have an average x-y plane gap size (GS) across the entire absorbent structure.

[0251] Article according to any one of embodiments A1 to A5, wherein the backsheet (30) comprises a polymer film.

[0252] Article according to any one of embodiments A1 to A6, wherein the topsheet (20) comprises a nonwoven fibrous web material.

[0253] Article according to embodiment A7, wherein the nonwoven fibrous web material is a spunbond nonwoven fibrous web material.

[0254] Article according to any one of embodiments A1 to A8, wherein a deposit of adhesive (45) is provided between the absorbent structure (40) and the topsheet (20).

[0255] Article according to any one of embodiments A1 to A9, wherein a deposit of adhesive (45) is provided between the absorbent structure (40) and the backsheet (30).

[0256] Article according to any one of embodiments A9 or A10, wherein the deposit of adhesive between the absorbent structure and the topsheet is in the form of discrete sprayed droplets.

[0257] Article according to any one of embodiments A9 to A11, wherein the deposit of adhesive between the absorbent structure and the backsheet is in the form of a continuous film of adhesive.

[0258] A13. The article according to any one of embodiments A9 to A12, wherein the adhesive is used to hold discrete sheets (40s) in place relative to each other in the x-y plane occupied by the absorbent structure.

[0259] A14. The article according to any one of embodiments A1 to A13, wherein substantially all or all of the article has been incrementally stretched along the first stretching direction (51a) and the second stretching direction (51b) in a pattern with substantially no discontinuities in the stretched and non-stretched regions.

[0260] A15. The article according to any one of embodiments A1 to A14, wherein the article is configured as a feminine hygiene product or incorporated into a feminine hygiene product.

[0261] A16. The article according to any one of embodiments A1 to A14, wherein the article is configured as a wearable incontinence product or incorporated into a wearable incontinence product.

[0262] A17. The article according to any one of embodiments A1 to A14, wherein the article is incorporated into adult underwear clothing.

[0263] A18. The article according to any one of embodiments A1 to A14, wherein the article is incorporated into a diaper or training pants for children.

[0264] A19. A method for manufacturing an absorbent article (10), the method comprising the steps of:

[0265] Providing a topsheet material comprising extensible nonwoven fibrous web material;

[0266] Providing a backsheet material comprising an extensible film;

[0267] Providing absorbent structure material;

[0268] Combining the topsheet material, the backsheet material, and the absorbent structure material to form a composite fibrous web (400), wherein the absorbent structure material is disposed between the topsheet material and the backsheet material to form an absorbent structure (40);

[0269] Feed the composite fiber web (400) through a first nip between a first pair of crimping rollers (302, 306, 307, 308), the first pair of crimping rollers being configured to have corresponding mating / engaging ridges (302d, 306d, 307d, 308d) and grooves (302e, 306e, 307e, 308e), and thereby incrementally stretch the composite fiber web along a first crimping direction (51a, 51b), whereby the topsheet material and the backsheet material are each permanently / plastically deformed along parallel first crimping lines (50) oriented substantially perpendicular to the first crimping direction;

[0270] Feed the composite fiber web (400) through a second nip between a second pair of crimping rollers, the second pair of crimping rollers being configured to have corresponding mating / engaging ridges (302d, 306d, 307d, 308d) and grooves (302e, 306e, 307e, 308e), and thereby incrementally stretch the composite fiber web along a second crimping direction (51a, 51b) different from the first crimping direction, whereby the topsheet material and the backsheet material are each permanently / plastically deformed along parallel second crimping lines (50) oriented substantially perpendicular to the second crimping direction.

[0271] A20. The method according to embodiment A19, wherein the absorbent structure material breaks when passing through the first nip and the second nip, thereby forming a plurality of discrete sheets (40p) of the broken absorbent structure material between the topsheet material and the backsheet material.

[0272] A21. The method according to any one of embodiments A19 or A20, the method further comprising the step of disposing an adhesive at a first position between the surface of the absorbent structure material facing the wearer and the topsheet material.

[0273] A22. The method according to any one of embodiments A19 to A21, the method further comprising the step of disposing an adhesive at a second position between the outward-facing surface of the absorbent structure material and the backsheet material.

[0274] A23. The method according to any one of embodiments A21 or A22, wherein the adhesive is disposed in the form of discrete droplets.

[0275] A24. The method according to embodiment A22, wherein the adhesive is disposed in the form of a continuous film.

[0276] A25. The method according to any one of embodiments A19 to A24, wherein the absorbent structure material is absorbent foam material.

[0277] A26. The method according to embodiment A25, wherein the absorbent foam material is a HIPE foam material.

[0278] A27. The method according to any one of embodiments A19 to A25, wherein at least one and preferably both of the first pair of forming rolls and the second pair of forming rolls comprise a mating helical configuration of ridges (307d, 308d) and grooves (308d, 308e).

[0279] A28. The method according to embodiment A27, wherein at least one and preferably both of the first pair of forming rolls and the second pair of forming rolls are configured to have a helix angle (γ1, γ2), the helix angle being selected to effect a strain of the composite fiber web along a strain direction (51a, 51b) that forms an angle (α, β) of 5 degrees to 85 degrees, more preferably 15 degrees to 70 degrees, and even more preferably 30 degrees to 60 degrees with a lateral axis of the article, and / or to effect a strain along a deformation line (50) of the article that forms an angle (α, β) of 5 degrees to 85 degrees, more preferably 15 degrees to 70 degrees, and even more preferably 30 degrees to 60 degrees with a longitudinal axis of the article.

[0280] A29. The method according to embodiment A20 or any embodiment dependent on embodiment A20, wherein the forming rolls are configured to effect breaking of the absorbent structural material into sheets (40p) having an average x - y plane size of no greater than 15 mm, more preferably no greater than 10 mm, still more preferably no greater than 7 mm, and even more preferably no greater than 5 mm across the entire absorbent structure of the article.

[0281] A30. The method according to embodiment A20 or any embodiment dependent on embodiment A20, wherein the forming rolls are configured to effect breaking of the absorbent material into sheets (40p) having a gap (40s) therebetween, the gap having an average x - y plane gap size across the entire absorbent structure of the article of at least (0.04×C), more preferably (0.16×C), still more preferably (0.28×C), and even more preferably (0.4×C), or (0.04×C) to (0.48×C), or any sub - range thereof, where "C" is the average thickness of the absorbent structure (40).

[0282] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to represent the recited value and a range functionally equivalent around that value. For example, a dimension disclosed as "40 mm" is intended to represent "about 40 mm".

[0283] When a range of measured quantities or characteristic values is described and / or recited as being representative of the subject matter contemplated herein, such range is considered to include and contemplate any and all sub-ranges within the range.

[0284] Each document cited herein, including any cross-referenced or related patent or application, is incorporated herein by reference in its entirety, unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any one or more other references, teaches, suggests or discloses any such invention. Further, when any meaning or definition of a term in this invention conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to the term in this invention shall govern.

[0285] Although specific embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is intended that all such changes and modifications that fall within the scope of the invention be covered by the appended claims.

Claims

1. An absorbent article, said absorbent article comprising: a longitudinal axis and a lateral axis; a liquid-permeable topsheet having a garment-facing surface and an opposite wearer-facing surface; a liquid-impermeable backsheet having a garment-facing surface and an opposite wearer-facing surface; and an absorbent structure comprising an open-cell absorbent foam material disposed between said topsheet and said backsheet, wherein said absorbent article has been incrementally stretched along at least a first stretch direction and a second stretch direction different from said first stretch direction such that: said topsheet and said backsheet each comprise a plastically stretched region disposed substantially along a first plurality of deformation lines substantially perpendicular to said first stretch direction and a second plurality of deformation lines substantially perpendicular to said second stretch direction; wherein said absorbent foam material is broken into a plurality of discrete foam sheets substantially along said first plurality of deformation lines and said second plurality of deformation lines, wherein said discrete foam sheets are separated from adjacent sheets by gaps; wherein an adhesive of 15 gsm to 35 gsm, preferably 18 gsm to 32 gsm, more preferably 20 gsm to 30 gsm is positioned between said garment-facing surface of said topsheet and the wearer-facing surface of said discrete foam sheets and bonds said discrete foam sheets to said topsheet.

2. The absorbent article according to claim 1, said absorbent article further comprising an adhesive of 15 gsm to 35 gsm, preferably 18 gsm to 32 gsm, more preferably 20 gsm to 30 gsm, said adhesive being positioned between said wearer-facing surface of said backsheet and the garment-facing surface of said discrete foam sheets, wherein said adhesive bonds said discrete foam sheets to said backsheet.

3. The absorbent article according to claim 1 or 2, wherein said adhesive is in the form of discrete sprayed droplets.

4. The absorbent article according to claim 2, wherein said adhesive is in the form of a continuous film of adhesive.

5. The absorbent article according to any one of the preceding claims, wherein said discrete foam sheets are arranged across said absorbent structure in a continuous pattern, wherein said discrete foam sheets have an average x-y plane dimension of 2 mm to 15 mm.

6. The absorbent article according to any one of the preceding claims, wherein said absorbent structure has an average thickness (C), wherein said gaps between said discrete foam sheets have an average x-y plane gap dimension of 0.04×C to 0.48×C.

7. The absorbent article according to any one of claims 1 to 5, wherein said discrete foam sheets are separated from adjacent sheets by gaps of 0.3 mm to 1.2 mm.

8. The absorbent article according to any one of the preceding claims, wherein said backsheet comprises a polymeric film having a basis weight of 20 gsm to 28 gsm.

9. The absorbent article according to any one of the preceding claims, wherein said topsheet is a spunbond nonwoven material.

10. The absorbent article according to any one of the preceding claims, wherein the first plurality of deformation lines form an angle α with respect to the longitudinal axis, and the second plurality of deformation lines form an angle β with respect to the longitudinal axis, wherein each of the angles α and β is from about 5 degrees to 45 degrees, preferably from 15 degrees to 40 degrees, more preferably from 20 degrees to 38 degrees.

11. The absorbent article according to any one of the preceding claims, wherein the open-cell foam material is a high internal phase emulsion foam.

12. The absorbent article according to any one of the preceding claims, wherein a portion of the adhesive penetrates into the garment-facing surface of the topsheet and the wearer-facing surface of the discrete foam sheet.

13. The absorbent article according to any one of the preceding claims, wherein the plurality of discrete foam sheets are arranged in a continuous pattern extending across the entire absorbent structure.

14. The absorbent article according to any one of the preceding claims, wherein a portion of the plastically stretched region of the topsheet extends continuously from a first side of the topsheet to a second side of the topsheet.

15. The absorbent article according to claim 14, wherein the first side of the topsheet is a first longitudinal side edge and extends in a direction substantially parallel to the longitudinal axis, and the second side of the topsheet is a second longitudinal side edge and extends in a direction substantially parallel to the longitudinal axis.

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