Method for providing opening in a nonwoven web and opening nonwoven web

Abstract

A single step method for imparting a pattern of pores in a fibrous nonwoven web is disclosed. The method may include providing a pinned roller with a pattern of perforated pins thereon; providing an opposite roller; arranging the rollers so as to form a nip therebetween, wherein the nip has a practically zero gap between the top surface of the pin and the outermost surface of the opposing roller; providing thermal energy to one or both of the rollers; the rollers are rotated and the non-woven web is conveyed through the nip whereby material constituting the fibers of the non-woven web is at least partially melted and extruded from an area between the top surface of the pin and the opposing rollers and gathered on the web around a peripheral edge of the top surface of the pin. Also disclosed are the resulting features of the nonwoven web, as well as products in which it can be incorporated as a component.

Description

Background Art

[0001] Disposable absorbent articles (such as disposable baby diapers, absorbent training pants, incontinence pads, absorbent incontinence underwear, feminine hygiene pads / napkins, etc.) typically include a liquid-permeable top sheet facing the wearer, a liquid-impermeable back sheet or barrier layer facing outward, and an arrangement of an absorbent structure disposed between the top sheet and the back sheet. The top sheet and the back sheet are typically bonded to each other around the periphery of the absorbent structure and on its outside, thereby encapsulating and containing the components of the absorbent structure.

[0002] Web materials used to form the topsheet include polymeric films and nonwoven web materials.

[0003] When the film is used to form a topsheet, typically it will be formed or imparted with a pattern of apertures therethrough which provide passages through which fluid may pass from the wearer facing surface to the opposing surface and down to the components of the absorbent structure beneath.

[0004] Typical nonwoven web materials, formed from a batt of somewhat randomly oriented filaments and / or fibers that are consolidated to form a textile-like web, are inherently liquid permeable in many examples because the filaments and / or fibers (collectively referred to as "fibers") do not form a continuous film-like barrier even when consolidated, but rather form a porous network or matrix of randomly oriented fibers, the interstitial spaces between which provide passageways through which fluids can pass within the nonwoven structure.

[0005] However, depending on the filament and / or fiber size, filament and / or fiber composition, nonwoven basis weight, and the density of aggregation and consolidation of the filaments within the nonwoven structure, nonwoven web materials may, in some examples, resist the passage of fluid therethrough to some extent. For example, if the nonwoven is formed from relatively fine (i.e., having relatively low dtex or denier and / or relatively low average diameter / size) constituent fibers, is relatively densely consolidated, and has a relatively hydrophobic surface chemistry, then the nonwoven may tend to resist the passage of aqueous liquid therethrough under the conditions of intended use.

[0006] It should be understood that in some cases, the designer of absorbent articles may wish to introduce a wearer-facing topsheet formed by a nonwoven having a fiber component that provides a desired level of, for example, softness attributes and / or pliability, opacity, and resistance to fluid re-seepage of the absorbent structural components that have been transferred to the following. These attributes can be imparted to the topsheet nonwoven material by including, for example, relatively thin constituent fibers having a hydrophobic surface chemistry that are relatively densely consolidated in the nonwoven. Under the circumstances of intended use, such nonwoven materials may resist fluid passage, or may allow fluid to pass only at an unacceptably slow rate.

[0007] In order to increase the liquid permeability of this top sheet nonwoven material, product designers may choose to give nonwoven material hole patterns. These holes are holes that pass through the nonwoven material, which are relatively larger (usually at least one order of magnitude larger) than the space between fibers, and are usually easily visible and distinguishable to the naked eye when viewing the surface of the nonwoven material. The hole provides a relatively large channel that fluid can pass through more easily. Several process technologies for giving nonwoven web materials this hole have been developed.

[0008] In one method, holes are simply cold punched through the nonwoven web material. This method has the disadvantages of reducing the structural integrity (tensile strength) of the web material by cutting the fibers at the edges of the holes and making the web more susceptible to fuzzing or pilling, fiber shedding and abrasion.

[0009] In another method, a spunbond web of polymer fiber components may be passed through a nip between a pair of calender rolls, one or both of which may be heated and configured to emboss a pattern of small, discrete compressed and molten regions extending in the machine direction onto / into the web. The region has a reduced thickness and is composed of a compressed and molten polymer material from which the constituent fibers are spun. After this step, the web is passed through a nip between a pair of annular rolls (also referred to as grooved rolls) to incrementally stretch the web in a cross direction, which causes the fused regions to break and open in the cross direction, thereby producing holes or holes through the web. After ring rolling, the web is passed through a stretching roll and further stretched in the cross direction to remove (pull out) the wrinkles imparted by the annular roll. Examples of this process are described in US 5,916,661 and US 10,667,962. The disadvantages of this process may include significantly reducing the structural integrity and tensile strength (particularly in the cross direction) of the web material and reducing the opacity of the web. Additionally, the process is generally not suitable for nonwoven webs formed primarily or substantially of staple fibers because the ring rolling and further stretching operations pull the constituent fibers apart, substantially degrading if not effectively breaking up the web.

[0010] In another method, an apertured web can be produced by passing a precursor nonwoven web having a polymer fiber component through a nip between a pair of pin-socket rolls. The roll includes an apertured roll with a pattern of tapered apertured pins protruding radially outward; and a corresponding pattern of pin receiving sockets configured to receive the pins and allow the rolls to rotate together when the pins rotate through the nip without interference between the pins and the walls of the receiving sockets. The apertured roll can be heated. When the nonwoven web passes through the nip, the apertured pins penetrate the web and displace and separate the fibers of the web surrounding them in the xy direction relative to the web. The heat from the apertured roll softens the polymer component of the fibers, thereby helping to achieve permanent plastic deformation of the fibers, so that they remain in their displaced position and define the holes, and then the web leaves the nip. Disadvantages associated with this process include limitations on processing / production speed.

[0011] In yet another method, holes can be produced by hydraulic jet or by needling with a hydraulic jet stream. This process does not cut, heat, substantially plastically deform or melt fibers, but displaces them in the nonwoven to open and form holes. This method also has several disadvantages. Fibers that are displaced but not plastically deformed to their displaced positions may tend to return to the pre-displacement position and / or otherwise be displaced to the space occupied by the holes, and when the further downstream processing of the web material is performed, the holes and hole patterns are unstable. In addition, the hydraulic jet process requires a large amount of energy input when providing enough water and pressure to achieve the desired effect to the jet stream, removing / drying water from the web after the hydraulic jet and collecting and further processing the removed water. The disadvantages associated with this process also include restrictions on processing / production speed.

[0012] Thus, there remains an opportunity to develop an efficient and effective method for apertured nonwoven web materials that has efficient processing / production speeds and maintains structural integrity, desired aperture shape and patterning. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic plan view illustration of an example of an absorbent article in the form of a feminine hygiene pad.

[0014] Figure 2 It is along Figure 1 Schematic lateral cross-section of the feminine hygiene pad of FIG. 8 taken along midline 2 - 2 .

[0015] Figure 3 is a schematic perspective illustration of a pair of apertured rolls operating on a nonwoven web.

[0016] Figure 4is a schematic side view illustration of equipment on a production line including a pair of apertured rolls operating on a nonwoven web.

[0017] Figure 5A and Figure 5B are schematic side view illustrations of various alternative non-limiting examples of apertured roller pairs.

[0018] Fig. 6A and Figure 6B Schematic middle cross-sectional view and perspective view, respectively, of an example of a cotter pin.

[0019] Fig. 7A is a schematic enlarged cross-sectional illustration (taken along the yz plane) of an aperture pin operating on a portion of a nonwoven web in the nip between aperture rolls.

[0020] Figure 7B is a schematic enlarged cross-sectional illustration (taken along the yz plane) of an aperture pin operating on a portion of a nonwoven web in a nip between aperture rolls, in another example.

[0021] Figure 7C is a schematic enlarged cross-sectional illustration (taken along the yz plane) of an aperture pin operating on a portion of a nonwoven web in a nip between aperture rolls, in another example.

[0022] Fig. 8A is a schematic enlarged cross-sectional illustration (taken along the yz plane) of a portion of a nonwoven web having apertures therethrough.

[0023] Figure 8B In another example, a schematic enlarged cross-section (taken along the yz plane) of a portion of a nonwoven web having apertures therethrough is illustrated.

[0024] Fig. 9 is a schematic further enlarged cross-sectional (taken along the yz plane) illustration of the portion of the nonwoven web shown within circle 8 shown in FIG. 7 .

[0025] Fig. 10A is a schematic enlarged plan view (along the z-direction) of a portion of a nonwoven web including apertures.

[0026] Fig. 10B is an enlarged photograph of a portion of a nonwoven web after exiting the nip between the apertured roll and the counter roll.

[0027] Fig. 10C is a further enlarged photograph of a portion of the nonwoven web after exiting the nip between the apertured roll and the counter roll.

[0028] Fig.11is a plan view (in the z-direction) image of a portion of a nonwoven web material having a pattern of holes therethrough.

[0029] Fig.12 is a magnified plan view (along the z-direction) of a portion of a nonwoven web material having holes therethrough.

[0030] Fig.13 is a magnified plan view (along the z-direction) of a portion of a nonwoven web material having holes therethrough. DETAILED DESCRIPTION

[0031] definition

[0032] As used herein, the following terms shall have the meanings specified below:

[0033] "Absorbent article" refers to disposable wearable devices that absorb and contain liquids, and more specifically, devices that are placed against or adjacent to the wearer's body to absorb and contain various exudates discharged from the body. Absorbent articles may include diapers, training pants, adult incontinence underwear (e.g., liners, pads, and panties), and / or feminine hygiene products, including feminine hygiene pads (also known as, for example, "sanitary napkins," "menstrual pads," "panty liners," etc.). Such disposable devices are typically not made of materials suitable for durability against laundering, such as knitted or woven fabrics.

[0034] As used herein, the term "integrated" is used to describe fibers of nonwoven materials that have been interwoven, entangled, and / or pushed / pulled in the positive and / or negative z-direction (thickness direction of the nonwoven material). Some exemplary methods for integrating fibers of nonwoven webs include hydroentanglement and needle punching. Hydroentanglement (also referred to as "hydraulic needling" or ("water enhancement")) uses multiple high-pressure water jets directed to a precursor batt or aggregate of fibers transmitted in the machine direction to entangle fibers. Needle punching (also referred to as "needle punching") involves using needles of special features to mechanically push and / or pull fibers, precursor batts of fibers, or aggregates in the z-direction to entangle them with other fibers in the batt or aggregate.

[0035] As used herein, the term "combed" is used to describe the structural features of a specific type of nonwoven web material contemplated herein as an apertured topsheet material in some examples. Combed nonwoven webs are formed by fibers cut into specific limited lengths, which are otherwise referred to as "short length fibers". Short length fibers may have any selected length. For example, short length fibers may be cut into a length of up to 120 mm, as short as a length of 10 mm. However, if a particular group of fibers is short length fiber, the length of each fiber in the fibers in the combed nonwoven is approximately the same, i.e., short length. In the case of including more than one composition of fibers in a nonwoven web (e.g., a web including polypropylene fibers and viscose fibers), the length of each fiber of the same composition may be substantially the same, while the corresponding short fiber lengths of the corresponding fiber compositions may be different.

[0036] In contrast to staple fibers, filaments such as those produced by weaving, for example, in a spunbond or meltblown nonwoven web manufacturing process, are generally not short-length fibers. Instead, these filaments are sometimes characterized as "continuous" fibers, meaning that they have a relatively long and indefinite length and are not cut into specific lengths after weaving, as their staple counterparts do.

[0037] "Lateral" - with respect to an absorbent article such as a feminine hygiene pad or a component thereof, refers to the direction parallel to a horizontal line tangent to the front surface of the upper portion of the wearer's legs adjacent to the torso when the pad is worn normally and the wearer assumes a flat, square, normal standing position. The "width" dimension of any component or feature of an article such as a feminine hygiene pad is measured in the lateral direction. When the article or a component thereof is laid flat on a horizontal surface, the "lateral" direction corresponds to the lateral direction relative to the structure when it is worn, as defined above. With respect to an article such as a feminine hygiene pad that is opened and laid flat on a horizontal planar surface, "lateral" refers to the direction perpendicular to the longitudinal direction and parallel to the horizontal planar surface. With respect to an absorbent article, the "x-direction" is also a lateral direction.

[0038] The "lateral axis" of an absorbent article such as a feminine hygiene pad or component thereof is a lateral line that lies in the xy plane and bisects the length of the pad or component thereof when the pad or component thereof is laid flat on a horizontal surface. The lateral axis is perpendicular to the longitudinal axis.

[0039] "Longitudinal" - with respect to an absorbent article such as a feminine hygiene pad or a component thereof, refers to the direction perpendicular to the lateral direction. The "length" dimension of any component or feature of the article is measured along the longitudinal direction from its forward extent to its rearward extent. When an article such as a feminine hygiene pad or a component thereof is laid flat on a horizontal surface, the "longitudinal" direction is perpendicular to the lateral direction relative to the pad when it is worn, as defined above. With respect to an absorbent article, the "y-direction" is also the longitudinal direction.

[0040] The "longitudinal axis" of a feminine hygiene pad or component thereof is a longitudinal line that lies in the xy plane and bisects the width of the pad or component thereof when the pad is laid flat on a horizontal surface. The longitudinal axis is perpendicular to the lateral axis.

[0041] With respect to absorbent articles such as feminine hygiene pads, or components thereof, "xy plane" refers to any horizontal plane occupied by the horizontal surface or any layer of the article or component when lying flat on the horizontal surface.

[0042] With respect to absorbent articles (such as feminine hygiene pads or components thereof), the "z-direction" is the direction perpendicular / normal to the xy plane when laid flat on a horizontal surface.

[0043] The terms "top", "bottom", "upper", "lower", "above", "below", "below", "upper adjacent", "lower adjacent" and similar terms characterizing relative vertical positioning, when used herein to refer to layers, components or other features of an absorbent article (such as a feminine hygiene pad), are relative to the z-direction and are to be interpreted relative to the pad as it would appear when laid flat on a horizontal surface, with the wearer-facing surface of the pad oriented upward and the outward-facing surface oriented downward.

[0044] With respect to absorbent articles such as feminine hygiene pads, or components or structures thereof, "wearer-facing" is a relative positional term that refers to a feature of a component or structure that is closer to the wearer when in use than another feature of the component or structure. For example, a topsheet has a wearer-facing surface that is closer to the wearer than an opposite, outwardly facing surface of the topsheet.

[0045] With respect to absorbent articles such as feminine hygiene pads, or components or structures thereof, "outwardly facing" is a relative positional term referring to a feature of a component or structure that is further away from the wearer when in use than another feature of the component or structure. For example, a topsheet has an outwardly facing surface that is further away from the wearer than an opposite, wearer-facing surface of the topsheet.

[0046] As used herein, with respect to absorbent articles (such as feminine hygiene pads or components thereof), "machine direction" or "MD" refers to the direction parallel to the flow of the article or component through processing / manufacturing equipment. With respect to the manufacture of fibrous web materials, the "y-direction" is the direction parallel to the machine direction.

[0047] As used herein, with respect to absorbent articles (such as feminine hygiene pads or components thereof), the "cross direction" or "CD" refers to the direction perpendicular / orthogonal to the machine direction. With respect to the manufacture of web materials, the "x direction" is the direction parallel to the cross direction.

[0048] When used to characterize the amount of weight, volume, surface area, etc. of an absorbent article or part thereof that is composed of a composition, material, feature, etc., "mainly" and its forms mean that the majority of such weight, volume, surface area, etc. of the absorbent article or part thereof is composed of the composition, material, feature, etc.

[0049] General – Absorbent products; feminine hygiene pads

[0050] See also Figure 1 and Figure 2 , an absorbent article as contemplated herein (such as a feminine sanitary pad 300) will have a longitudinal axis 400 and a lateral axis 500, and include a wearer-facing surface and an opposite outward-facing surface. A liquid-permeable top sheet 301 may form at least a portion of the wearer-facing surface, and a liquid-impermeable back sheet may form at least a portion of the outward-facing surface. An absorbent structure 302 is disposed between the top sheet and the back sheet. The absorbent structure 302 may include a fluid management layer 302a and a storage layer 302b. (The fluid management layer as described herein is sometimes referred to in the art as a "collection / distribution layer", "distribution layer" or "secondary top sheet", and its purpose is to dissipate the energy from the fluid outflow to the desired extent, provide a temporary spatial volume for the discharged fluid to occupy during the time required for the underlying absorbent structure (storage layer) to receive and absorb the fluid, and distribute the fluid through the absorbent structure to maximize its effective utilization). Non-limiting examples of absorbent articles that share these characteristics include feminine hygiene pads (also known as "sanitary napkins," "menstrual pads," etc.), disposable incontinence pads, disposable incontinence underwear, disposable infant diapers, and disposable infant / child training pants. Non-limiting examples of suitable absorbent structures / storage layers are described in co-pending U.S. Provisional Application Serial No. 63 / 256,164, which is incorporated herein by reference. Non-limiting examples of suitable absorbent structures / storage layers are described in co-pending U.S. Provisional Application Serial No. 63 / 316,097, which is incorporated herein by reference.

[0051] The top sheet 301 and the back sheet 303 may be joined together to form and define the outer perimeter of the pad. The absorbent structure 302 and its components or layers (e.g., the fluid management layer 302a and the storage layer 302b) will be sized such that their outer perimeters are laterally and longitudinally disposed inboard of the outer perimeters. The components or layers of the absorbent structure 302 may have dimensions and shapes in the xy directions that are substantially similar or identical to one another, or they may have correspondingly different xy dimensions and / or shapes. The individual layers may be manufactured to have dimensions such as Figure 1The stadium shape suggested in , or one or both may be manufactured to have any other suitable shape, such as an oval shape, a rectangular shape, a rounded rectangular shape, an hourglass shape, a peanut shape, etc. Shapes with concave contours along the longitudinal edges (e.g., an hourglass shape) may provide enhanced comfort and / or conformity to the wearer's body in some examples.

[0052] The top sheet 301 may be joined to the back sheet 303 by any suitable attachment mechanism. The top sheet 301 and the back sheet 303 may be directly joined to each other in the periphery of the article, and may be indirectly joined together by directly joining them to the absorbent structure 302, the fluid management layer 302a and / or the storage layer 302b and / or additional layers disposed between the top sheet 301 and the back sheet 303. This indirect or direct joining may be achieved by any suitable attachment mechanism known in the art. Non-limiting examples of attachment mechanisms may include, for example, melt bonding, ultrasonic bonding, pressure bonding, adhesive bonding, or any suitable combination thereof.

[0053] The panty liner 300 may include a pair of oppositely disposed lateral extensions (sometimes referred to as "wings") 304 that do not include absorbent components. The wings 304 may be formed by or include lateral extensions of one or both of the top sheet 301 and back sheet 303 materials. The wings 304 may also include a deposit of an adhesive (not shown) on its outwardly facing surface. With this configuration, the user may properly position and place the panty liner 300 in the crotch region of her panties, and wrap and fold the wings 304 downward, over and around the respective edges of the leg openings, and then adhere the wings 304 to the outside / underside of the panty crotch region. Positioned in this manner, the wings 304 may help keep the pad in place during wear / use, and help protect the panties from contamination around the leg edges.

[0054] Top sheet

[0055] General Description

[0056] It is usually desired that the top sheet 301 is compliant, soft in feel, and non-irritating to the wearer's skin. Suitable top sheet materials will include liquid-permeable materials, which are arranged on the wearer-facing side of the articles, and will contact the wearer's body in this position. Preferably, the top sheet will be configured to allow the fluid discharged to penetrate through it quickly, and desirably, is not easy to allow fluid to move back upwards through the top sheet and contact the wearer's skin. The top sheet also may be suitable for carrying and / or providing the selected lotion composition provided with the articles to transfer or migration to the wearer's skin. The top sheet may include nonwoven material or may be formed by nonwoven material.

[0057] The nonwoven web to be used as a component of the top sheet can be produced by any known process for making nonwoven webs, non-limiting examples of which include spunbonding, carding, wet-laid, air-laid, meltblown, needle-punched, mechanical entanglement, thermo-mechanical entanglement, and hydroentanglement.

[0058] Nonwoven materials suitable for use as top sheet component materials may include a layer of aggregated fibers or a laminate of multiple aggregated fiber layers, which may include similar or different compositions (e.g., spunbond-meltblown laminates). In a specific example, the top sheet may be formed from a carded through-air bonded nonwoven web material.

[0059] The topsheet contemplated herein does not include any major portion of the topsheet xy surface area occupied by the membrane. Some currently known topsheets for feminine hygiene pads include an apertured membrane, such as a hydroformed membrane or a vacuum formed membrane, alone or in combination with an adjacently disposed nonwoven web material. The membrane can help prevent liquid from resurfacing and contacting the wearer. However, the inventors have found that a topsheet having the features described herein, for example, when combined with a properly constructed and constructed fluid management layer (e.g., as disclosed in co-pending U.S. Provisional Application Serial No. 63 / 256164), can effectively prevent back-seepage to a pad having a topsheet including a membrane spanning a major portion of the topsheet xy surface area, comparable to or better than that of a pad. Without intending to be bound by theory, it is believed that careful selection of the fiber type and the linear density of the fiber type in each layer in the layering of the fluid management layer can result in a desired combination of appropriately low liquid acquisition time and low back-seepage, overcoming the typical compromises in these conflicting goals associated with existing nonwoven topsheets. The improved performance is evident from the new combination of a unique nonwoven topsheet with the fluid management layer of the present disclosure.

[0060] In addition to the features described herein, the nonwoven web material used to form the top sheet may also have any of the features, structures, components and / or compositions described in, for example, co-pending U.S. provisional application serial numbers 63 / 256,164 and 63 / 316,097, the disclosures of which are incorporated herein by reference.

[0061] Basis Weight

[0062] The top sheet nonwoven can be manufactured to have a basis weight of at least about 15gsm, more preferably at least about 40gsm or most preferably at least about 60gsm, specifically listing all values ​​in these scopes and any scope set up thus.In some examples, the nonwoven top sheet envisioned herein can be manufactured to have a basis weight of about 15gsm to 80gsm, more preferably about 20gsm to 60gsm or most preferably about 20gsm to 40gsm, specifically listing all values ​​in these scopes and any scope set up thus.In a specific example, the top sheet nonwoven can be manufactured to a basis weight of about 18gsm to 40gsm, more preferably about 20gsm to 30gsm, even more preferably about 22gsm to 26gsm, specifically listing all values ​​in these scopes and any scope set up thus.The scope of ideal basis weight is subject to the needs of the required web tensile strength level for processing and the substantial preference influence of the consumer on opacity level and thickness, sensation and outward appearance at the lower limit of the scope. The range of desirable basis weights is influenced at the upper end of the range by the need for adequate rapid fluid acquisition and fluid penetration through the topsheet as well as material cost issues.

[0063] Fiber composition

[0064] Non-limiting examples of constituent materials suitable for use in the top sheet nonwoven include fibrous materials made from natural fibers (e.g., cotton (including 100% organic cotton), modified natural fibers, semi-synthetic fibers (e.g., fibers spun from regenerated cellulose), synthetic fibers (e.g., fibers spun from polymer resins), or combinations thereof. Synthetic fibers may include fibers spun from a single polymer or a blend of polymers. Synthetic fibers may include monocomponent fibers, bicomponent fibers, or multicomponent fibers. (In this article, bi- or multi-component fibers are fibers having a cross-section that is divided into clearly identifiable component parts, each of which is formed from a single polymer or a single homogeneous polymer blend, as distinct from the other parts. Such fibers and methods for making them are known in the art. Examples of bicomponent fiber constructions having a substantially circular cross-section include side-by-side or "fan-shaped" constructions, eccentric sheath-core constructions, and concentric sheath-core constructions.

[0065] The nonwoven top sheet contemplated herein may include fibers having countless combinations of constituent components. For example, the fibers may be spun from polymer materials such as polyethylene (PE) and / or polyethylene terephthalate (PET). The fibers may be spun in the form of bicomponent fibers. In some examples, the bicomponent fibers may have a core component of a first polymer (e.g., PET) and a combination of another polymer as a sheath component, in a sheath-core bicomponent configuration. In a more specific example, PE may be combined with a PET core component to form a sheath component. Fibers including a PET component may be selected to help provide a body and resilience and a resulting cushion feel to the nonwoven web. In addition, fibers including a PET component having considerable resilience help the web maintain the area and size of the holes (if included) produced therein.

[0066] Other polymer materials may be included. For example, fibers spun from polypropylene, polyethylene, copolyethylene terephthalate, copolypropylene and other thermoplastic resins may be included. It may be desirable that when a sheath-core bicomponent fiber is included, the polymer with the lower melting temperature forms the sheath component. Additionally, without intending to be bound by theory, it is believed that using polyethylene terephthalate as the core component may help impart resilience to the top sheet.

[0067] Compared with other potentially useful polymers, polyethylene, as a polymer component that can be spun into fibers, has a relatively low melting temperature and exhibits a relatively smooth / silky surface feel. PET has a relatively high melting temperature and exhibits relatively large rigidity and resilience. Therefore, in some examples, it is desirable to have a top sheet nonwoven fiber with a skin-core bicomponent structure, wherein the skin component is mainly polyethylene and the core component is mainly PET. Polyethylene can be used to impart a silky feel to the fiber and thus to the top sheet, and can be used to cause the skin of adjacent / contacting fibers to melt and fuse at a lower melting temperature of polyethylene via heat treatment to achieve fiber-to-fiber bonding, while PET can be used to impart resilience, and due to its higher melting temperature, it will not melt during the heat treatment process involving a properly controlled temperature. The inventors have found that a suitable weight ratio in such PE / PET skin-core bicomponent fibers can be from about 40:60 to about 60:40.

[0068] The constituent fibers may be staple fibers. The staple fibers may be carded and consolidated to produce a web having cohesiveness and tensile strength via hydroentanglement or other suitable methods of integrating and / or entangling the fibers. In some examples, the web may be calendered to impart additional consolidation and tensile strength. However, in other examples, calendering may be preferred because it may reduce web thickness and bulk, reduce porosity, increase web stiffness, and adversely affect or reduce other softness attributes that may be perceived by consumers.

[0069] Surface treatment (hydrophilicity / hydrophobicity)

[0070] Depending on its chemical composition, the surface of a fiber will be inherently hydrophilic or hydrophobic. For example, the surface of a fiber spun or otherwise formed by some types of polymers (such as polyethylene and polypropylene) will be inherently hydrophobic. In contrast, the surface of other types of fibers such as fibers spun from regenerated cellulose (e.g., rayon, viscose, lyocell, etc.) is inherently hydrophilic. The surface of natural fibers may be inherently hydrophilic or hydrophobic, but this may depend on the treatment that the fiber has undergone. For example, harvested cotton fibers carry a coating of natural wax, and therefore their surface is hydrophobic. However, after they have undergone a process including scrubbing and bleaching, the wax will be stripped, making the fiber surface hydrophilic.

[0071] Manufacturers and / or suppliers of spun synthetic staple fibers currently apply coatings in the form of surface finishes or processing aids to the fibers for the purpose of providing lubricity during, for example, the carding process. These surface finishes or processing aids can be formulated to be hydrophobic or hydrophilic and are substantially durable for purposes herein because they will not dissolve in aqueous fluids over the normal wearing duration of the absorbent article. Therefore, manufacturers or suppliers of spun synthetic staple fibers can provide fibers with a hydrophobic or hydrophilic surface finish, and currently, several manufacturers in the nonwovens industry do so.

[0072] It is noteworthy that spun synthetic staple fibers can be obtained having a surface that is inherently hydrophobic or hydrophilic, or having a surface finish that makes its surface hydrophilic or hydrophobic at the option of the purchaser, and it may be desirable to select fibers having a surface that is hydrophilic ("hydrophilic fibers") or hydrophobic ("hydrophobic fibers"), or a blend of these two types of fibers.

[0073] In some examples, it may be preferred that the fiber component of the top sheet is mainly, substantially or completely hydrophobic by weight, or is rendered hydrophobic via the fiber surface finish. A top sheet formed from a nonwoven web having mainly hydrophobic fiber components will resist rewetting. On the other hand, if the size of the pores or interfiber spaces within the fibrous structure of such a nonwoven web is not large enough, the top sheet may prevent fluid from passing through the wearer-facing surface to the absorbent core component of the article below it, i.e., fluid will not be easily / quickly collected unless other features as described herein are included in combination.

[0074] In other examples, some, most (by surface area), or all of the fibers that make up the cross-section of the web material from which the top sheet is formed may be a blend of both hydrophobic and hydrophilic fibers. In such examples, the hydrophilic fibers may be used to help wick fluid downward from the wearer-facing surface of the top sheet to the absorbent core component below, while the hydrophobic fibers may be used to help the top sheet prevent rewetting. The inventors have found that a successful balance can be achieved for such examples.

[0075] Therefore, in some examples, the top sheet nonwoven fabric may include a mixture of hydrophobic fibers and hydrophilic fibers.For example, the nonwoven fabric may include at least about 40% by weight, more preferably at least about 50% by weight, or most preferably at least about 60% by weight of the hydrophilic fibers by the weight of the fiber, specifically including all values ​​in these ranges and any scope established thereby.In more specific examples, the nonwoven top sheet may include about 40% by weight to 70% by weight, more preferably about 45% by weight to 68% by weight, or most preferably from about 50% by weight to 65% by weight of the hydrophilic fibers, specifically listing all values ​​in these ranges and any scope established thereby.The top sheet nonwoven fabric may include a blend of hydrophilic fibers and hydrophobic fibers, and the weight ratio of hydrophilic fibers to hydrophobic fibers is 30:70 to 70:30, more preferably 35:65 to 65:35 and even more preferably 40:60 to 60:40.As mentioned above, the hydrophilicity of the hydrophilic fibers may be affected by applying a surface treatment composition.

[0076] Without intending to be bound by theory, it is believed that where a majority of the fibers are hydrophilic, fluid acquisition rates can be improved by combining with the other features described herein without unduly affecting rewet in an unfavorable or unacceptably unfavorable manner. Where less rewet is the goal, the opposite may be true. In this case, a higher weight fraction of hydrophobic fibers may be desirable.

[0077] Line density

[0078] Fibers are typically manufactured, selected, and purchased based on linear density specifications expressed as denier or decitex. For fibers of a given polymer composition, linear density is related to fiber size / diameter.

[0079] In some examples, the fibers constituting the top sheet may be selected to have an average linear density of about 1.0 denier to 3.0 denier, more preferably about 1.5 denier to 2.5 denier, and even more preferably about 1.8 denier to 2.2 denier, and all combinations of sub-ranges within these ranges are contemplated herein. In other examples, the fibers constituting the top sheet may be selected to have an average linear density of about 3.0 denier to 5.0 denier, more preferably about 3.5 denier to 4.5 denier, and even more preferably about 3.8 denier to 4.2 denier, and all combinations of sub-ranges within these ranges are contemplated herein.

[0080] Without intending to be bound by theory, it is believed that for nonwovens of a specific selected basis weight as contemplated herein, inclusion of fibers having a linear density greater than about 5.0 denier may result in a topsheet that lacks a sufficiently soft feel for some consumers, since such relatively large fibers will tend to be harder. Conversely, selection of fibers having a linear density less than about 1.0 denier results in too small interstitial spaces / voids between and among the fibers, and makes fluid acquisition and movement through the topsheet unacceptably difficult unless holes are included. In any case, a suitable hole pattern may be imparted to the topsheet to increase liquid permeability.

[0081] Short fiber length

[0082] Suitable fibers may be staple fibers having a length in the following ranges: at least about 30 mm, 40 mm, or 50 mm, up to about 55 mm, or about 30 mm to about 55 mm, or about 35 mm to 52 mm, with increments of 1 mm listed for the ranges. In a specific example, the staple fibers may have a length of about 38 mm.

[0083] hole

[0084] The inventors have found that in a topsheet nonwoven formed of relatively small size / linear density fibers and / or fibers that are primarily, substantially or completely hydrophobic, the acquisition speed can be increased significantly by forming a pattern of holes through the web. Typically, the preferred holes will have a size that is substantially larger than the average hole / void size (size of the inter-fiber spaces) within the nonwoven web.

[0085] An example of a cross-section of an apertured topsheet nonwoven web material 20 having a pattern of apertures 21 therethrough is depicted in FIG. Fig.11 An enlarged image of an example of a hole through a nonwoven web material is depicted in FIG. Fig.12The pores are distinguishable from randomly disposed pores or voids through the nonwoven web material in that they are produced by readily discernible displacement of fibers and / or fiber component materials in the xy direction, thereby producing a concentrated group of dense material and / or displaced fibers defining a perimeter 22 of z-direction pores / openings through the nonwoven web that are relatively larger than the randomly distributed pores or voids between and in the fibers comprising the nonwoven material.

[0086] The holes can be produced through the fiber web via the methods and apparatus described herein and are configured to impart a 0.1 mm 2 Up to 2.5mm 2 , preferably 0.3 mm 2 Up to 1.5mm 2 , and even more preferably 0.3 mm 2 Up to 1.2mm 2 , and even more preferably 0.3 mm 2 Up to 0.5mm 2 The average xy dimension pore area of ​​20 is defined herein as the average xy dimension pore area of ​​20, and all combinations of sub-ranges within these ranges are contemplated herein. Herein, the xy dimension area of ​​the pore is defined by the visually discernible inside edge of the dense zone 23 around the perimeter 22 of the pore. Individual fibers that may have left the main structure and / or the dense zone around the perimeter and passed through the deviation into or through the main opening area of ​​the pore (by way of example, Fig.12 1 to 1:1.2; more preferably, 2:1 to 1:2; even more preferably, 1.5:1 to 1:1.5; still more preferably, 1.3:1 to 1:1.3; and most preferably, 1.2:1 to 1:1.2; all combinations of sub-ranges within these ranges are contemplated herein. Furthermore, for the purposes of maintaining the structural integrity of the web and the shape integrity of the apertures, it is preferred that at least in the region of interest 305 ("ROI," defined hereinafter; see Figure 1 The xy plane shape of most or all of the apertures in the top sheet (if not most or all of the top sheet) is substantially circular in shape (e.g., circular, oval, ovate, elliptical, stadium-shaped, etc.) without defined sharp corners. Thus, it may be desirable for the pins on the roller used to create the apertures to have a radially outermost active surface having a shape that does not define sharp corners when viewed in a radially inward direction toward the axis of the roller.

[0087] The amount of hole area for all holes in the portion of interest of the topsheet is summed up to the xy plane area of ​​the openings in the topsheet nonwoven ("open area"). In combination with the desired average hole size, the inventors have determined the desired open area in order to effectively mitigate potential obstacles to fluid acquisition that may be caused by finer denier fibers and / or a composition of fibers that are primarily hydrophobic. Thus, it can be expected that the holes (if included) collectively provide an open area of ​​1% to 25%, more preferably 1% to 20%, more preferably 3% to 15%, and even more preferably 4% to 10%. All combinations of sub-ranges within these ranges are contemplated herein. Preferably, such an amount of open area is substantially present in the entire portion of the topsheet covering the fluid management layer and / or absorbent structure, or at least present as defined below (and see Figure 1 ) in a region of interest 305 ("ROI"). The lower end of these ranges is limited by the need for efficacy / performance; the apertures should provide at least a minimum amount of open area in order to be effective as may be included for the purposes described herein. The upper end of these ranges is limited by the need for consumer acceptance; if the open area is too large, the consumer may perceive the topsheet as fragile or of poor quality; and further, the topsheet becomes less effective in retaining fluids beneath it and in masking stains caused by absorbent fluids present in the absorbent component beneath the topsheet.

[0088] See also Figure 1 For purposes contemplated herein, the region of interest 305 ("ROI") is a rectangular cross-section of the topsheet that is 60.0 mm long in the longitudinal direction and 30.0 mm wide in the lateral direction and is centered in the xy plane at the longitudinal and lateral centers of the topsheet 300. The open area percentage fraction of the ROI 305 is the fraction of the xy area therein that is open in the z direction by the co-existence of apertures therethrough. In other words, the open area percentage fraction within the ROI is the total open xy area of ​​the apertures within the ROI divided by 1,800 mm 2 Multiply by 100%.

[0089] In some examples, the open area percentage fraction in the ROI may be obtained from instructions given or provided by the manufacturer of the top sheet nonwoven web material. Where this is not available, it may be measured via any applicable suitable measurement technique in a manner consistent with the above description of the xy dimension area of ​​the aperture area and the description of "open area", which may include but is not limited to the "aperture open area measurement method" described below.

[0090] Bonding

[0091] In some examples, it is desirable that the fibers forming the top sheet nonwoven be bonded after the carding / fiber placement process to give the web a fabric-like structure and tensile strength (in both MD and CD) required to substantially maintain its structure in the downstream / later process, and in the form of a top sheet during use by the user / wearer. As an alternative to other bonding methods such as mechanical compression point bonding (e.g., calendering bonding) (with or without applying thermal energy), adhesive bonding, etc., it has been found that bonding via ventilation heating is effective for producing fiber-to-fiber bonding portions and imparting structural integrity to the web, while maintaining inter-fiber pore / void size and bulkiness, and imparting nonwoven resilience. It may be desirable to maintain elastic bulkiness in this way to mitigate the potential bulkiness / thickness reduction effect that may be caused by the aperture process described herein, wherein the web is compressed between aperture rollers. In an example of a suitable method, when the carded web is conveyed through an oven or a heating chamber along the machine direction on a conveyor belt, air heated to a selected heating temperature is blown and / or drawn (via vacuum) through the carded web. When the operating parameters including the heated air temperature and velocity and the exposure time are appropriately adjusted, a plurality of randomly distributed fiber-to-fiber bonds can be generated within the fiber network, which imparts structural integrity to the fiber web. Examples of such fiber-to-fiber bonds 17 can be found at Fig.13 When the constituent fibers are, for example, sheath-core bicomponent fibers, where the sheath component is a polymer having a melting temperature lower than that of the core component, the process can be configured so that a melt bond is formed between the sheaths of adjacent contacting fibers without complete melting and loss of the sheath structure, while the core remains in place, unmelted. In such a process, the bond can be formed without applying z-direction compression or its effects, and therefore, without an associated loss of web thickness and reduction in the size of the inter-fiber pores / voids.

[0092] Hole cutting methods, resulting features and material selection

[0093] See also Figures 3 to 6B , schematically depicts a generally cylindrical apertured roll operating on a portion of a nonwoven web material, including an apertured roll 100 and a counter roll 120. The precursor web material 10 may be conveyed from an upstream supply source 200 in a machine direction MD into a nip 110 between the apertured roll 100 and the counter roll 120, one or both of which are driven to rotate about axes parallel to each other and having cross directions. The apertured nonwoven web material 20 leaves the nip 110, having an arrangement of apertures 21 (e.g., of a desired size, shape, and configuration) imparted therein. Fig.11 ), as shown in the non-limiting example in FIG.

[0094] The perforated roller 100 may have formed thereon and about an arrangement of individual perforated pins 101 that protrude radially outward from a base surface 106 of the roller 100. The perforated pins 101 have a top surface 102 having a surface area that is in the shape of an imaginary cylinder. The top surface 102 of the perforated pins 101 is preferably smooth and polished with substantially no macroscopic cavities or irregularities therein. The area of ​​the top surface 102 is defined and bounded by a top surface peripheral edge 103. Preferably, at least after manufacture of the roller and before the pins wear due to their use, the top surface peripheral edge 103 is defined by an angled, non-circular transition away from the top surface 102. As shown in FIG. Fig. 6A and Figure 6B As shown, a small chamfer 103a around the top surface peripheral edge 103 may be included to reduce stress concentrations at the edge and the chance of cracking around it. However, the top surface peripheral edge 103 is not substantially radial or rounded at the transition away from the top surface 102. (The reasons for this are explained below.) For the purpose of mechanical structural integrity of the pin 101, preferably, the pin base perimeter 105 will define a larger surface area at the pin base than the surface area of ​​the top surface 102, and the pin wall 104 will taper inwardly toward each other from the pin base perimeter 105 to the pin top surface perimeter 103. In this regard, the angle α between the top surface 102 and the pin wall 104 is preferably greater than 90 degrees. The pin may be concavely radial or rounded around the base perimeter 105 to reduce local stresses at the pin base perimeter during use of the roller.

[0095] The top surface 102 of the aperture pins 101 can be given any desired shape and size, generally corresponding to the desired xy-direction shape and size of the holes to be formed in the subject nonwoven web material. Similarly, the aperture pins 101 can be arranged on the aperture roll 100 in any desired pattern, generally corresponding to the desired xy-direction pattern of the holes to be formed in the subject nonwoven material.

[0096] For purposes of structural integrity, preferably, the aperture pin 101 and the portion of the aperture roller forming its base surface 106 are integral, formed from the same continuous piece of material. A major portion, if not the entire aperture roller, may be integrally formed from the same continuous piece of material. Preferably, the material forming the pin 101 and base surface 106 will be relatively hard and rigid, such as a suitable steel or alloy thereof. In some examples, the pin 101 or at least the top surface 102 may be imparted with a suitably selected non-stick or anti-stick coating to avoid or reduce adhesion of the material to be melted and / or deformed in the nip.

[0097] In some examples, the cotter pin 101 may be formed by machining or otherwise removing material from a solid cylinder, leaving material that defines and constitutes the pin 101 .

[0098] In some examples, such as Figure 4 As shown, the opposing roller 120 may have a simple cylindrical outer surface that will meet all of the top surfaces 102 of the opening pins 101 in the nip 110 between the rollers 100 and 120. In other examples, such as Figure 5A As shown, the opposing roller 120 may have an opposing structure 122 formed thereon that effectively mirrors and meets the top surface 102 of the perforating pin 101 on the perforating roller 100. In other examples, such as Figure 5B As shown, the opposing roll 120 may have opposing structures 122 formed and arranged thereon that are constructed and arranged to meet a desired subset (one or more, but not all) of the top surfaces 102 of the aperture pins 101 in the nip 110. In these latter examples, flexibility in providing various selections of different configurations or patterns of apertures may be provided by manufacturing and selecting to use different opposing rolls operating with the aperture roll 100. In the case where only selective area apertures of the nonwoven material are desired, these latter configurations may also enable the useful life of the aperture roll 100 to be extended because not all aperture pins 101 need to be used at the same time.

[0099] As with the perforated roller 100 and perforated pin 101, it is preferred that the material forming the surface of the counter roller 120 and / or any of its counter structures 122 is relatively hard and rigid. These surfaces may also be imparted with a suitably selected non-stick or anti-stick coating.

[0100] When configured for operation, the aperture roll 100 and the opposing roll 120 are preferably arranged so that there is substantially no or virtually no (zero) specified clearance in the nip 110 between the top surface 102 of the aperture pin 101 and the opposing surface of the opposing roll 120. Referring to FIG. 7 , with this configuration, the polymer material forming the constituent fibers of the precursor nonwoven web material will plastically deform and extrude from the nip region between the top surface 102 of the aperture pin and the opposing roll surface as indicated by the double-headed arrow in FIG. 7 to a region beginning at the peripheral edge 103 of the top surface 102 of the pin 101 and extending beyond the peripheral edge in the xy direction. Referring to FIG. 7 to FIG. Fig. 10C , resulting in a dense hole perimeter zone 23. Depending on the composition of the nonwoven fiber 15 components and the operating temperature of the roll, the dense zone 23 may include a dense polymer material of fiber components that have been melted and then fused, unmelted but plastically deformed and extruded, or a combination thereof. The formation of the dense zone 23 defining the holes 21 stabilizes the size and shape of the holes within the open-cell nonwoven fiber web 20.

[0101] like Figure 7B , Figure 7C and Figure 8BAs shown, in some cases, the dense area 23 in the open-aperture fiber web 20 caused by the extrusion of material from the roller gap area between the top surface 102 of the opening pin 101 and the opposite roller surface 121 may be relatively larger and / or denser in the upstream area 23u near the hole periphery 22 (near the upstream edge 103u of the top surface 102) in the roller gap, and relatively smaller and / or less dense in the downstream area near the hole periphery 22 opposite to the upstream area (near the downstream edge 103d of the top surface 102). Without intending to be bound by theory, it is believed that when the system is configured as described herein to specify that the gap between the top surface 102 of the pin 101 and the opposing roller surface 121 is substantially zero, the downstream edge 103d and the portion of the top surface 102 will be closest to or in contact with the opposing roller surface 121 first in time, and as the roller rotates, the closest proximity or contact between the top surface 102 of the pin will proceed in a rolling manner from the downstream edge 103d of the top surface 102 of the pin toward the upstream edge 103u. As a result, as the precursor web material 10 passes through the nip, the system will tend to extrude more material of the precursor web material in the upstream direction than in the downstream direction relative to the web material 10. (Herein, "upstream" refers to the direction opposite to the machine direction MD in which the web travels through the nip, and "downstream" refers to the same direction as the direction MD in which the web travels through the nip).

[0102] Either or both of aperture roll 100 and counter roll 120 may be heated to a temperature at or above the melting temperature of one or more of the polymer components of the web fiber constituents to facilitate such deformation and / or melting and fusing.

[0103] Even when the rollers are configured to have a substantially zero or practically zero specified gap in the nip 110, it may be difficult to fully extrude the fiber component material trapped in the nip region between the pin top surface 102 and the opposing roller surface 121. This may be the result of microscopic surface defects in the pin top surface 102 and / or the opposing roller surface 121 and / or some compliance intentionally provided in the corresponding roller structure or roller bearing and / or drive mechanism and structure, where an unfeasibly large amount of pressure in the nip would be required to extrude all of the material from the nip region between the top of the perforated pin and the opposing roller surface. The latter situation would exist in examples where a fiber component is present in the subject nonwoven web that is brittle or substantially inextensible and is therefore crushed and flattened under the pins, but not extruded. Such examples may include nonwoven web materials that are partially composed of fibers that are composed of non-thermoplastic materials such as regenerated cellulose (e.g., rayon, viscose, lyocell, etc.). In some examples, it may be desirable to include one or both of the rollers, or the roller bearing and / or drive mechanisms and structures, with features that provide limited compliance at a given pressure, i.e., allowing the rollers to separate to a limited extent at a given nip pressure at nip 110 to define the maximum pressure in the nip applied to pin surface 102 to reduce the chance of roller wear and pin failure. As a result, when the apertured web 20 exits nip 110, a very thin / low thickness film 21a of unextruded polymer and / or other fiber component material (shown in one example at Fig. 10B 21a may be retained within the aperture 21. However, when the component materials of the web constituent fibers are appropriately selected as described below, the film 21a will readily break away and leave the web, leaving an open aperture 21. The resulting aperture 21 may have a broken edge 24 around its perimeter 22, which will be the remaining portion of the film 21a after the majority of it has been severed. When the peripheral edge 103 of the pin top surface 102 is clearly defined, as described above, the amount of the film that forms the broken edge 24 will be minimized, i.e., the breaking of the film will desirably occur very close to the dense area 23 and the aperture perimeter 22.

[0104] In some cases, when the nonwoven web 20 leaves the nip 110, the unextruded film material may break away from the holes 21 and adhere to one or both of the pin top surface 102 and the opposing roller surface 106. To address this issue, the system can be provided with an online roller cleaning device 130a and / or 130b. Such roller cleaning equipment can consist of or include one or more scrapers, brushes (which themselves can be configured to operate on counter-rotating rollers), a system of one or more pressurized air knives, a water jet, or any combination thereof, or any other suitable roller cleaning device.

[0105] If the component materials of the nonwoven constituent fibers are appropriately selected, the above-described methods and mechanisms can effectively impart pores to nonwoven webs at relatively high production rates, thereby contributing to manufacturing efficiency.

[0106] As described herein, in some examples, the desired top sheet nonwoven web material may be partially or completely composed of bicomponent fibers having a first polymer component and a second polymer component. In such examples, it may be desirable that the corresponding polymer components have different melting temperatures. When the melting temperatures of the corresponding components are sufficiently different, the above-mentioned fiber web aperture system may be operated, wherein one or both of the rollers 100, 120 are heated to a temperature sufficient to melt one of the polymer components but not melt the other. Doing so causes the polymer component with a lower melting temperature to melt and easily flow out from below the aperture pin top surface 102, exceeding the top surface peripheral edge 103. At the same time, the polymer component with a higher melting temperature will not melt, and when it is extruded from below the pin top surface 102 in the roller gap 110, it is not only forced to plastically deform but also forced to rupture. The film of the unextruded material that may be left when the fiber web leaves the roller gap 110 will be mostly composed of the component with a higher melting temperature, which will desirably rupture into fragments that will easily fall or pull out of the hole.

[0107] To achieve or enhance this effect, it may be desirable for the first polymer component and the second polymer component of the bicomponent fiber composition to have a melt temperature differential of at least about 44° C., more preferably at least about 72° C., and even more preferably at least about 100° C. This provides the operator with a wide range of temperatures to which the operator may heat one or both of the aperture rolls to melt the first polymer component having the lower melt temperature while avoiding melting of the second polymer component having the higher melt temperature.

[0108] In some examples (such as those described herein), a suitable topsheet nonwoven may be composed of a sheath-core bicomponent fiber, wherein polyethylene terephthalate (PET) constitutes the core component and polyethylene (PE) constitutes the sheath component. PET has a melting temperature of about 264°C, which is relatively high among the potential thermoplastic polymer components considered suitable for spinning fibers that can be used for the purposes contemplated herein. This relatively high melting temperature leaves considerable room for the selection of a second suitable polymer, because most currently known suitable thermoplastic polymers suitable for spinning fibers that can be used for the purposes of the present invention have a melting temperature significantly lower than 264°C. In addition, PET is relatively brittle and tends to break more easily than other suitable polymers, rather than being plastically deformed in a ductile manner under heavy pressure, which is desirable for the reasons described above. In contrast, PE has a melting temperature of about 110°C to 130°C (depending on the specific form), and will flow easily above the melting temperature. This makes it suitable as a nonwoven constituent fiber component for the purposes described above, including forming a stable dense zone 23 around the pores, which helps stabilize the pores and their configuration / pattern within the nonwoven material during downstream processing and converting operations. As described above, PE also imparts other desirable properties to nonwovens.

[0109] It is contemplated that the above method can be applied to two different nonwoven web materials at the same time. As described above, two different nonwoven web materials 10 can be conveyed together through the nip 110 between the apertured roll 101 and the relative roll 120. When the materials leave the nip, they will each have holes 21 aligned in the z direction. The corresponding nonwoven web materials will be bonded together to a certain extent by the thermoplastic fiber component material at the dense area 23 around the corresponding aligned holes 21, which has been melted and extruded from the bottom of the apertured pin 101 in the nip, and then fused. For example, the top sheet nonwoven web material and the fluid management layer nonwoven material described in the references described herein or incorporated by reference herein can be put together and apertured in the above manner. The fluid management layer can be constructed as described in, for example, U.S. Provisional Application Serial No. 63 / 316,097. In some examples, the fluid management layer may include any combination of monocomponent fibers, hollow monocomponent fibers, bicomponent fibers, cellulose fibers, and regenerated cellulose fibers. Bicomponent fibers can be spun to have a sheath-core structure including a PET core component. The sheath component can be PE. Hollow monocomponent fibers can be spun from PET.

[0110] As described, the perforated pin 101 can be formed with a top surface 102 having various surface areas and shapes, corresponding to the area and shape of the hole that is desired to be given to the subject nonwoven fiber web. It should be understood that the substantially circular hole 21 in the fiber web may be the most effective per unit surface area for providing fluid passage. Similarly, a shape having an aspect ratio (aspect ratio of machine direction dimension to cross direction dimension) close to 1:1 is relatively effective compared to a shape having an aspect ratio in which any one size is significantly greater than or less than another size. The method and apparatus described herein can be configured to effectively give a nonwoven fiber mesh pattern, wherein the hole in the pattern has an average aspect ratio of 2.5:1 to 1:2.5, more preferably 2:1 to 1:2, even more preferably 1.5:1 to 1:1.5, still more preferably 1.3:1 to 1:1.3 and most preferably 1.2:1 to 1:1.2.

[0111] The above method does not require sufficient stretching of the web in the machine or cross direction in a subsequent step to open the holes after it leaves the nip.

[0112] Test and measurement methods

[0113] thickness

[0114] The thickness of the specimen is measured as the distance between the reference platform on which the specimen rests and the pressure foot which applies a specified amount of pressure to the specimen for 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 specimens are conditioned in this environment for at least 2 hours prior to testing.

[0115] Thickness is measured with a manually operated micrometer equipped with a pressure foot capable of applying a steady pressure of 0.50 kPa ± 0.01 kPa to the specimen. The manually operated micrometer is a deadweight instrument that reads to the nearest 0.01 mm. A suitable instrument is a Mitutoyo series 543 ID-C Digimatic, or equivalent, available from VWR International. The pressure foot is a flat circular movable surface that is smaller in diameter than the specimen and that is capable of applying the required pressure. A suitable pressure foot has a diameter of 25.4 mm, but smaller or larger pressure feet may be used depending on the size of the specimen being measured. The specimen 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 in accordance with the manufacturer's instructions.

[0116] If necessary, obtain the sample by removing it from the absorbent article. When cutting the sample from the absorbent article, be careful not to cause any contamination or deformation to the sample layer during the process. The sample is taken from an area without folds or wrinkles and must be larger than the pressure foot.

[0117] To measure thickness, first zero the micrometer relative to a horizontal flat reference platform. Place the specimen on the platform with the test position centered under the pressure foot. Gently lower the pressure foot at a rate of descent of 3.0mm ± 1.0mm per second until full pressure is applied to the specimen. Wait 5 seconds, then record the thickness of the specimen to the nearest 0.001mm. Repeat in a similar manner for a total of ten replicate test specimens. Calculate the arithmetic mean of all thickness measurements and report as "Thickness" to the nearest 0.001mm.

[0118] Basis Weight

[0119] The basis weight of a sample of sheet or web material is the mass (in grams) per unit area (in square meters) of a single material layer. If it is not otherwise known or available, the basis weight can be measured using EDANA Pharmacopoeia Method NWSP130.1. The mass of the test sample is cut into a known area, and the mass of the test sample is determined using an analytical balance accurate to 0.0001 grams. All measurements are performed in a laboratory maintained at 23°C ± 2°C and 50% ± 2% relative humidity, and the test sample is conditioned in this environment for at least 2 hours before testing.

[0120] The test samples taken from the raw material roll or raw material sheet or the test samples obtained from the material layer removed from the absorbent article are measured. When the material layer is cut from the absorbent article, it is important not to cause any contamination or deformation to the layer during the process. The cut layer should be free of residual adhesive. In order to ensure that all adhesive is removed, the layer is soaked in a suitable solvent that will dissolve the adhesive without adversely affecting the material itself. One such solvent is THF (tetrahydrofuran, CAS 109-99-9, which is used for general purposes and is purchased from any convenient source). After the solvent soak, the material layer is allowed to air dry thoroughly in a manner that prevents excessive stretching or other deformation of the material. After the material has dried, the sample is obtained. The sample must be as large as possible to take into account any inherent material variability.

[0121] Measure the dimensions of the single-layer specimen using a calibrated steel metal ruler from NIST or equivalent. Calculate the area of ​​the specimen and record it to the nearest 0.0001 square centimeter. Use an analytical balance to obtain the mass of the specimen and record it to the nearest 0.0001 gram. Calculate the basis weight by dividing the mass (in grams) by the area (in square meters) and record it to the nearest 0.01 gram / square meter (gsm). Repeat in a similar manner for a total of ten replicates. Calculate the arithmetic mean of the basis weight and report it to the nearest 0.01 gram / square meter.

[0122] Material composition analysis

[0123] If the information is not available otherwise, the quantitative chemical composition of test specimens comprising a mixture of fiber types is determined using ISO 1833-1. All tests are carried out in a laboratory maintained at 23°C ± 2°C and 50% ± 2% relative humidity.

[0124] The test samples taken from the raw material roll or raw material sheet or the test samples obtained from the material layer removed from the absorbent article are analyzed. When the material layer is cut from the absorbent article, care is taken not to cause any contamination or deformation to the layer during the process. The cut layer should be free of residual adhesive. In order to ensure that all adhesive is removed, the layer is soaked in a suitable solvent that will dissolve the adhesive without adversely affecting the material itself. One such solvent is THF (tetrahydrofuran, CAS 109-99-9, which is used for general purposes and purchased from any convenient source). After the solvent soak, the material layer is allowed to air dry thoroughly in a manner that prevents excessive stretching or other deformation of the material. After the material has dried, the sample is obtained and tested according to ISO 1833-1 to quantitatively determine its chemical composition.

[0125] Average fiber dtex or denier

[0126] Textile webs (e.g., woven webs, nonwoven webs, air-laid webs) are composed of individual material fibers. In one aspect, the fibers are characterized by their linear mass density, reported in denier or decitex. The decitex value is the mass (in grams) of the fibers present in 10,000 meters of the fiber. The denier value is the mass (in grams) of the fibers present in 9,000 meters of the fiber. The average decitex or denier value of the fibers in the web of the material is often reported by the manufacturer as part of the specification. If the average decitex or denier value of the fiber is not otherwise known or available, it can be calculated by measuring the cross-sectional area of ​​the fiber via a suitable microscopic technique such as a scanning electron microscope (SEM), determining the composition of the fiber with a suitable technique such as FT-IR (Fourier transform infrared) spectroscopy and / or DSC (dynamic scanning calorimetry), and then using the literature value of the density of the composition to calculate the mass (in grams) of the fibers present in 10,000 meters of fiber (for decitex) or 9,000 meters of fiber (for denier).

[0127] All tests were conducted in a chamber maintained at a temperature of 23°C ± 2.0°C and a relative humidity of 50% ± 2%, and the samples were conditioned at the same ambient conditions for at least 2 hours prior to testing.

[0128] If desired, a representative sample of the web material of interest can be cut out from the absorbent article. In this case, the web material is removed in order to prevent the sample from being stretched, deformed or contaminated.

[0129] SEM images were obtained and analyzed as follows to determine the cross-sectional area of ​​the fibers. In order to analyze the cross-section of a sample of a fiber web material, a specimen was prepared as follows. A sample of approximately 1.5 cm (height) × 2.5 cm (length) and no creases or wrinkles was cut from the fiber web. The sample was immersed in liquid nitrogen and the edge was broken along the length of the sample with a razor blade (No. 9 VWR single-edged industrial razor blade, surgical carbon steel). The sample was sputter-coated with gold and then adhered to the SEM mount using double-sided conductive tape (Cu, 3M, purchased from electron microscopy sciences). The sample was oriented so that the cross section was as perpendicular to the detector as possible to minimize any tilt distortion of the measured cross section. SEM images were obtained at a resolution sufficient to clearly illustrate the cross section of the fibers present in the sample. The fiber cross section may vary in shape, and some fibers may be composed of multiple individual filaments. In any case, the area of ​​each cross section in the fiber cross section was determined (e.g., using the diameter of a circular fiber, the major and minor axes of an elliptical fiber, and image analysis for more complex shapes). If the fiber cross section indicates a non-uniform cross-sectional composition, the area of ​​each identifiable component is recorded and the decitex contribution of each component is calculated and then summed. For example, if the fiber is bicomponent, the cross-sectional areas of the core and sheath are measured separately and the decitex contributions from the core and sheath are calculated separately and summed. If the fiber is hollow, the cross-sectional area does not include the interior portion of the fiber composed of air, which does not contribute significantly to the fiber decitex. In summary, at least 100 such measurements of cross-sectional area are made for each fiber type present in the sample and reported in square micrometers (µm 2 ) is used as the unit to record the cross-sectional area a of each fiber k The arithmetic mean value (accurate to 0.1µm) 2 ).

[0130] The fiber composition is determined using common characterization techniques such as FTIR spectroscopy. For more complex fiber compositions (such as polypropylene core / polyethylene sheath bicomponent fibers), a combination of common techniques (e.g., FTIR spectroscopy and DSC) may be required to fully characterize the fiber composition. This process is repeated for each fiber type present in the fiber web material.

[0131] Average decitex of each fiber type in the web material k The value is calculated as follows:

[0132]

[0133] where d k In grams (per 10,000 m of calculated length), a k In µm 2 is a unit, and ρk In grams per cubic centimeter (g / cm 3 ) units. Report the average dtex to the nearest 0.1 g per 10,000 m of calculated length and the fiber type (e.g., polypropylene (PP), PET, cellulose, PP / PET bicomponent). The average denier value for each fiber type in the web material is its dtex. k value × 0.9.

[0134] Hole Open Area Percentage Measurement Method

[0135] The open area percentage is measured on an image of an open top sheet sample collected using a flatbed scanner. The scanner is capable of scanning in reflective mode at a resolution of 2400 dpi and 8-bit grayscale. A suitable scanner is an Epson Perfection V750 Pro purchased from Epson America Inc. (Long Beach, California, USA), or one having substantially similar functionality. The scanner interacts with a computer running an image analysis program. A suitable program is ImageJ v. 1.47 (National Institute of Health, USA), or a program having substantially similar functionality. The sample image is distance calibrated based on the collected image of a ruler certified by NIST. In order to achieve maximum contrast, the sample is backed with an opaque background sheet of uniform black color before the image is collected. All measurements are performed in a conditioning room maintained at about 23 ± 2°C and about 50 ± 2% relative humidity.

[0136] The measurement samples were prepared as follows.

[0137] Obtain the desired number of samples of the absorbent article of interest. To obtain a measurement sample, tap the sample absorbent article around its perimeter (i.e., not taped on the area below the fluid management layer), with the wearer-facing side facing up, to a horizontal flat work surface in a flat configuration. Any elastic material included (e.g., in the leg cuffs), if present, may be cut to facilitate laying the article flat. Identify and mark the outer boundaries of the apertured topsheet area covering the fluid collection layer of the article. Now cut through the topsheet and any adhered underlying layers with a new razor blade or other reasonably new sharp cutting tool, around and through the marked outer boundaries. Then carefully separate the sample of the apertured topsheet from the cut-out portion and remove it from the underlying layers so that its longitudinal and lateral dimensions are not changed to avoid deformation of the apertures. If the topsheet is adhered to the underlying layers via an adhesive, apply any solvent suitable for dissolving the adhesive and allowing the topsheet to be easily separated from the underlying layers without dissolving the polymer material of the fibers constituting the nonwoven web material of the topsheet before attempting separation. (In many examples, tetrahydrofuran (THF) may be a suitable solvent for this purpose. As long as the solvent does not dissolve the polymer that makes up the fiber itself, there is no need to worry about whether the solvent dissolves the surface finish coating applied to the fiber.) Once the cut portion of the top sheet that makes up the measurement sample is removed, its wearer-facing side is identified. Five replicate measurement samples obtained from five samples of the absorbent article of interest are prepared for measurement. Prior to imaging, the samples are conditioned at about 23°C ± 2°C and about 50% ± 2% relative humidity for 2 hours.

[0138] The images were obtained as follows.

[0139] A ruler was placed on the scanning bed so that it was oriented parallel to the side of the scanner glass. An image of the ruler (calibration image) was acquired in reflection mode at a resolution of 2400 dpi (approximately 94 pixels / mm) and 8-bit grayscale. The calibration image was saved as an uncompressed TIFF format file. After the calibration image was obtained, the ruler was removed from the scanner glass and all samples were scanned under the following scanning conditions.

[0140] Place the measurement sample flat onto the center of the scanning bed, with the body-facing surface of the sample facing the glass surface of the scanner. Fix the corners and edges of the sample so that its original longitudinal and lateral dimensions (as on the article before removal) are maintained. The sample is oriented so that its major and minor axes are aligned parallel and perpendicular to the sides of the glass surface of the scanner, respectively. Place a black background on top of the sample, close the scanner lid, and acquire a scanned image of the entire sample with the same settings as those used for the calibration image. Save the sample image as an uncompressed TIFF format file. Scan and save the remaining four replicate samples in a similar manner.

[0141] The sample image is analyzed as follows. The calibration image file in the image analysis program is opened, and the image resolution is calibrated using an imaging ruler to determine the number of pixels per millimeter. The sample image in the image analysis program is now opened, and the distance scale is set using the image resolution determined from the calibration image. Now identify a rectangular cross-section (region of interest, or "ROI") centered longitudinally and laterally on the sample, which has a longitudinal dimension of 60.0 mm and a lateral dimension of 30.0 mm along the longitudinal axis, and visually inspect the image of the hole present in the ROI. Now using the software tool, manually outline each hole in the hole in the ROI (and any part of it at the edge of the ROI). Appropriate contours will be drawn around the periphery of the hole along the visually discernible inner edge of the concentrated portion of the displacement fiber 503. The individual fibers that may have left the main structure and / or the concentrated portion of the displacement fiber around the periphery and passed through the deviation of the main opening area of ​​the hole (by way of illustration, the individual fibers 504 of the deviation shown in Figure 5) are not considered to be subtracted from the hole area for the purpose of this article. ) The software was then used to measure the area within each discrete hole outline (full and partial) within the ROI and record each to the nearest 0.01 mm 2 , and their sum is calculated. The area of ​​each discrete hole is defined as the xy surface area within the visually discernible outline of the open area, which is produced by the mechanical penetration of the fiber web and the xy direction displacement of the fibers during the opening process, which produces the hole through the fiber web. (For example, see Figure 5, which depicts the discrete hole area 501 and the visually discernible boundary 502. The dark area of ​​the depicted hole is an image of the black construction paper used as the backing of the sample, and this particular image was made from this sample.) The sum of the areas of all holes within the ROI is recorded as the "hole area" to the nearest 0.01mm 2 Now divide the “hole area” by the ROI area (1,800mm 2 ), then multiply by 100 and record as the "opening area" to the nearest 0.1%.

[0142] In a similar manner, the entire procedure was repeated for the remaining four replicate images. The arithmetic mean of the "Open Area" across all five replicates was calculated and reported as the "Mean Open Area" to the nearest 0.1%.

[0143] Non-limiting embodiments contemplated herein

[0144] In view of the above description, the following non-limiting examples of combinations of features are contemplated herein: other features described herein may also be included where feasible.

[0145] 1. A single-step method for imparting a pattern of holes (21) in a fibrous nonwoven web (10) consisting primarily of staple fibers, the single-step method comprising the following steps:

[0146] Providing a pinned roller (100) having a first axis and carrying a pattern of perforated pins (101) extending radially outwardly therefrom, wherein the perforated pins have a radially outermost top surface (102) that is substantially smooth and contoured along a cylindrical shape about the first axis, the top surface having a peripheral edge (103) about which a surface area of ​​the top surface is defined;

[0147] providing an opposing roller (120) having a second axis;

[0148] arranging the counter roller and the pinned roller to form a nip (110) therebetween, wherein the first axis and the second axis are substantially parallel, and wherein the nip has a substantially zero gap between the top surface of the opening pin and one or more outermost surfaces of the counter roller,

[0149] wherein the relative roller comprises one or more radially outermost surfaces (121), the one or more radially outermost surfaces being cylindrical about the second axis and being arranged on the relative roller so as to relatively contact the top surface of the opening pin in the roller gap;

[0150] providing thermal energy to one or both of the pinned roller and the opposing roller;

[0151] rotating the pinned roller and the counter roller and conveying the fibrous nonwoven web through the roller gap,

[0152] The material of the fibers (15) constituting the nonwoven web is thereby at least partially melted and extruded outwardly from the nip region between the top surface of the pin and the opposing roller toward the peripheral edge (103) of the top surface of the pin when the pin meets the opposing roller in the nip (110), and

[0153] The fibrous material thus extruded gathers to form a densified region (23) around the peripheral edge (103) of the top surface (102) of the pin (101), the densified region being retained with the nonwoven web as it exits the nip;

[0154] An open hole pattern is thereby imparted to the web, the hole pattern corresponding to the pattern of the aperture pins, thereby providing an apertured nonwoven web (20).

[0155] 2. A method according to embodiment 1, wherein the peripheral edge (103) of the outermost top surface (102) of the opening pin (101) defines a shape having an average aspect ratio of 2.5:1 to 1:2.5, more preferably 2:1 to 1:2, even more preferably 1.5:1 to 1:1.5, still more preferably 1.3:1 to 1:1.3 and most preferably 1.2:1 to 1:1.2.

[0156] 3. The method according to embodiment 1 further comprises the step of through-air bonding the fibrous nonwoven web (10) or the apertured nonwoven web (20) before or after the step of conveying the fibrous nonwoven web (10) through the roller gap.

[0157] 4. An open-cell nonwoven web (20) comprising staple fibers, the open-cell nonwoven web having a pattern of holes (21) therethrough, wherein each of a plurality of the holes is surrounded by a dense aggregate of material (23) of the fibers constituting the nonwoven web, the material being plastically deformed and / or fused via z-applied local z-direction compression and optionally applied heat.

[0158] 5. An open-pore nonwoven web according to Example 4, wherein the dense aggregate of material (23) is relatively larger and / or denser in a first region (23u) of a first portion of the periphery (22) near each of the plurality of holes, and relatively smaller and / or less dense in a second region (23d) of a second portion of the periphery (22) near each of the plurality of holes, wherein the first portion of the periphery is arranged opposite to the second portion of the periphery.

[0159] 6. An apertured nonwoven web according to Example 5, wherein the first portion of the periphery is disposed on the upstream side of each of the plurality of holes, and the second portion of the periphery is disposed on the downstream side of each of the plurality of holes, wherein "upstream" and "downstream" are relative to a machine direction, and the apertured nonwoven web passes through the gap between a pair of apertured rollers along the machine direction.

[0160] 7. The apertured nonwoven web of any one of embodiments 4 to 6, comprising a plurality of randomly distributed fiber-to-fiber bonds (17) therein, the fiber-to-fiber bonds not exhibiting a z-direction compression effect during their formation.

[0161] 8. An apertured nonwoven web according to any one of Examples 4 to 7, wherein the apertures in the pattern have an average aspect ratio of 2.5:1 to 1:2.5, more preferably 2:1 to 1:2, even more preferably 1.5:1 to 1:1.5, still more preferably 1.3:1 to 1:1.3 and most preferably 1.2:1 to 1:1.2.

[0162] 9. The method or apertured nonwoven web of any preceding embodiment, wherein the fibrous nonwoven web comprises bicomponent fibers.

[0163] 10. The method or apertured nonwoven web of embodiment 9, wherein the bicomponent fibers are of a sheath-core bicomponent construction having a sheath component and a core component.

[0164] 11. The method or apertured nonwoven web of embodiment 10, wherein the core component comprises a polymer selected from the group consisting of PET, PP and PE and combinations thereof, and preferably PET.

[0165] 12. The method or apertured nonwoven web of any one of embodiments 10 or 11, wherein the sheath component comprises PE, preferably predominantly PE.

[0166] 13. A method or apertured nonwoven web according to any of the preceding embodiments, wherein the constituent fibers of the fibrous nonwoven web include fibers that are primarily, substantially or completely hydrophobic in weight proportion, or fibers that are rendered hydrophobic by fiber surface finishing.

[0167] 14. The method or apertured nonwoven web according to any of the preceding embodiments, wherein the fibrous nonwoven web (10) comprises a first layer component having a first fiber composition and a second layer component having a second fiber composition different from the first fiber composition.

[0168] 15. The method or apertured web of embodiment 14, wherein the first layer comprises primarily hydrophobic fibers and the second layer comprises primarily hydrophilic fibers.

[0169] 16. The method or apertured nonwoven web of any of Embodiments 14 or 15, wherein the second fiber construction comprises a combination of bicomponent fibers and hollow monocomponent fibers.

[0170] 17. The method or apertured nonwoven web of embodiment 16, wherein the hollow monocomponent fibers comprise PET.

[0171] 18. The method or apertured nonwoven web of any one of embodiments 14 to 17, wherein the second fiber composition comprises cellulosic fibers.

[0172] 19. The method or apertured nonwoven web of embodiment 18, wherein the cellulosic fibers comprise regenerated cellulose.

[0173] 20. An apertured nonwoven web made by the method of any of embodiments 1 to 3 or 9-19.

[0174] 21. A feminine hygiene pad comprising a liquid permeable top sheet, a liquid impermeable back sheet and an absorbent structure disposed between the top sheet and the back sheet, wherein the top sheet comprises the apertured nonwoven web according to any one of the preceding embodiments.

[0175] * * *

[0176] The dimensions and values ​​disclosed herein should not be understood as being strictly limited to the exact numerical values ​​cited. Instead, unless otherwise indicated, each such dimension is intended to represent the stated value and a functionally equivalent range around that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm".

[0177] Unless expressly excluded or otherwise limited, each document cited herein, including any cross-referenced or related patent or patent application and any patent application or patent to which this application claims priority or the benefit of, is hereby incorporated by reference in its entirety. The citation of any document is not an admission that it is prior art to any of the present invention disclosed or claimed herein, or an admission that it, by itself or in combination with any one or more of the references, proposes, suggests, or discloses any such invention. In addition, to the extent that 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 that term in this invention shall govern.

[0178] Although specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the present invention. Therefore, it is intended that all such changes and modifications within the scope of the present invention be covered in the appended claims.

Claims

1. A single-step method for imparting a pattern of holes (21) in a fibrous nonwoven web (10) consisting primarily of staple fibers, the single-step method comprising the following steps: Providing a pinned roller (100) having a first axis and carrying a pattern of perforated pins (101) extending radially outwardly therefrom, wherein the perforated pins have a radially outermost top surface (102) that is substantially smooth and contoured along a cylindrical shape about the first axis, the top surface having a peripheral edge (103) about which a surface area of ​​the top surface is defined; providing an opposing roller (120) having a second axis; arranging the opposing roller and the pinned roller to form a roller gap (110) therebetween, wherein the first axis and the second axis are substantially parallel, and wherein the roller gap has a substantially zero clearance between the top surface of the opening pin and one or more outermost surfaces of the opposing roller, wherein the opposing roller comprises one or more radially outermost surfaces (121), the one or more radially outermost surfaces being cylindrical about the second axis and being arranged on the opposing roller so as to relatively contact the top surface of the opening pin in the roller gap; providing thermal energy to one or both of the pinned roller and the opposing roller; rotating the pinned roller and the counter roller and conveying the fibrous nonwoven web through the roller gap, whereby the material of the fibers (15) constituting the nonwoven web is at least partially melted and extruded outwardly from the nip region between the top surface of the pin and the opposing roller toward the peripheral edge (103) of the top surface of the pin when the pin meets the opposing roller in the nip (110), and the fibrous material thus extruded is gathered to form a densified zone (23) around the peripheral edge (103) of the top surface (102) of the pin (101), the densified zone being retained with the nonwoven web as the nonwoven web exits the nip; A pattern of open holes is thereby imparted to the web, the hole pattern corresponding to the pattern of the aperture pins, thereby providing an apertured nonwoven web (20).

2. The method of claim 1, wherein the peripheral edge (103) of the outermost top surface (102) of the cotter pin (101) defines a shape having an average aspect ratio of 2.5:1 to 1:2.5, more preferably 2:1 to 1:2, even more preferably 1.5:1 to 1:1.5, still more preferably 1.3:1 to 1:1.3, and most preferably 1.2:1 to 1:1.

2.

3. The method according to claim 1, further comprising the step of through-air bonding the fibrous nonwoven web (10) or the apertured nonwoven web (20) before or after the step of conveying the fibrous nonwoven web (10) through the roller gap.

4. An open-cell nonwoven web (20) comprising staple fibers, the open-cell nonwoven web having a pattern of holes (21) therethrough, wherein each of a plurality of said holes is surrounded by a dense aggregate of material (23) of the fibers constituting the nonwoven web, the material being plastically deformed and / or fused via z-applied local z-direction compression and optionally applied heat.

5. An open-cell nonwoven web according to claim 4, wherein the dense aggregate of material (23) is relatively larger and / or denser in a first area (23u) near a first portion of the periphery (22) of each of the plurality of holes, and is relatively smaller and / or less dense in a second area (23d) near a second portion of the periphery (22) of each of the plurality of holes, wherein the first portion of the periphery is arranged opposite to the second portion of the periphery.

6. The apertured nonwoven web according to claim 5, wherein the first portion of the periphery is disposed on the upstream side of each of the plurality of holes, and the second portion of the periphery is disposed on the downstream side of each of the plurality of holes, wherein "upstream" and "downstream" are relative to a machine direction along which the apertured nonwoven web passes through the gap between a pair of apertured rollers.

7. The apertured nonwoven web according to any one of claims 4 to 6, comprising a plurality of randomly distributed fiber-to-fiber bonds (17) therein, wherein the fiber-to-fiber bonds do not exhibit a z-direction compression effect during their formation.

8. The apertured nonwoven web of any one of claims 4 to 7, wherein the apertures in the pattern have an average aspect ratio of 2.5:1 to 1:2.5, more preferably 2:1 to 1:2, even more preferably 1.5:1 to 1:1.5, still more preferably 1.3:1 to 1:1.3 and most preferably 1.2:1 to 1:1.

2.

9. The method or apertured nonwoven web of any one of the preceding claims, wherein the fibrous nonwoven web comprises bicomponent fibers.

10. The method or apertured nonwoven web of claim 9, wherein the bicomponent fibers are of a sheath-core bicomponent construction having a sheath component and a core component.

11. The method or apertured nonwoven web of any of the preceding claims, wherein the constituent fibers of the fibrous nonwoven web include fibers that are predominantly, substantially or completely hydrophobic in weight proportion, or fibers that have been rendered hydrophobic by fiber surface finishing.

12. The method or apertured nonwoven web of any of the preceding claims, wherein the fibrous nonwoven web (10) comprises a first layer component having a first fiber composition and a second layer component having a second fiber composition different from the first fiber composition.

13. The method or apertured nonwoven web of claim 12, wherein the first layer comprises primarily hydrophobic fibers and the second layer comprises primarily hydrophilic fibers.

14. An apertured nonwoven web made by the method of any one of claims 1 to 3 or 9 to 13.

15. A feminine hygiene pad comprising a liquid permeable top sheet, a liquid impermeable back sheet and an absorbent structure disposed between the top sheet and the back sheet, wherein the top sheet comprises the apertured nonwoven web according to claims 4 to 14.

Images