Feminine hygiene pad with absorbent foam and reservoir spacer layer - Patents.com

Abstract

A feminine hygiene pad is disclosed having an absorbent system including an absorbent foam layer having a wearer-facing surface and an outward-facing surface and having a plurality of apertures providing z-directional passageways from the wearer-facing surface to the outward-facing surface, and a porous spacer layer beneath the foam layer and underlying most of the openings of the apertures in the outward-facing surface of the foam layer. The spacer layer functions to provide structure beneath the absorbent foam layer to hold open a desired amount of unoccupied space between the absorbent layer and the backsheet of the pad, into which unabsorbed menstrual fluid can flow and reside temporarily for the time required for the absorbent layer to effectively wick the fluid.

Description

[Background technology]

[0001] Feminine hygiene pads comprising open-cell foam absorbent materials can be manufactured to have good absorbency, a relatively low profile / caliper, and a soft, conforming, resilient, and cushiony feel—a combination of characteristics highly valued by feminine hygiene pad users. However, for some users, it may be desirable for the pad to provide a faster acquisition rate than currently associated with such pads, and additionally or alternatively, a greater ability to effectively capture relatively rapid discharge of menstrual fluid. Particularly for users who tend to experience relatively heavy menstrual flow, a certain amount of menstrual fluid may collect in the vaginal cavity during periods of rest or relative inactivity and then be suddenly discharged by changing body movements. For such users, one or both of the above-mentioned enhancements can further reduce the risk of fluid leaking from the pad and soiling undergarments, outerwear, bedding, etc. before the pad can capture and contain the fluid. There is room for further improvement. [Brief explanation of the drawings]

[0002] [Figure 1] FIG. 1 is a top plan view of an example of a non-limiting feminine hygiene pad. [Figure 2A] 2 is a top plan view of a feminine hygiene pad similar to that shown in FIG. 1 shown with the topsheet layer removed and having two different non-limiting examples of aperture patterns. [Figure 2B] 2 is a top plan view of a feminine hygiene pad similar to that shown in FIG. 1 shown with the topsheet layer removed and having two different non-limiting examples of aperture patterns. [Figure 3A] 3 is a schematic transverse cross-sectional view of the pad of FIGS. 1 and 2A taken through line 3-3 of FIG. 1; [Figure 3B] FIG. 3B is an enlarged view of the pad shown in FIG. 3A. [Figure 4] FIG. 3B is an enlarged view of the pad shown in FIG. 3A in an alternative non-limiting example. [Figure 5]2 is an underside plan view of the feminine hygiene pad of FIG. 1 shown with the backsheet layer removed and illustrating the boundary between the central and peripheral regions of the spacer layer. FIG. [Figure 6A] 1 is a schematic enlarged view of a non-limiting example of an adhesive deposit in a discharge area. [Figure 6B] 1 is a schematic enlarged view of a non-limiting example of an adhesive deposit in a discharge area. [Figure 6C] 1 is a schematic enlarged view of a non-limiting example of an adhesive deposit in a discharge area. [Figure 7A] 6 is a schematic cross-sectional view of a measurement device configuration used in the transmittance measurement methods described herein, taken through a vertical plane that bisects the illustrated fluid container 601. FIG. [Figure 7B] FIG. 6B is a diagram of the measurement device shown in FIG. 6A, shown with added elements in preparation for initiating the measurement procedure. [Figure 7C] FIG. 6C is a diagram of the measurement device shown in FIG. 6B shown after the start of the measurement procedure. [Figure 8A] FIG. 1 is a perspective view of a sample weight used in the transmittance measurement method described herein. [Figure 8B] FIG. 7B is a top view of the sample weight shown in FIG. 7A. [Figure 8C] 7B is a vertical cross-sectional view of the sample weight shown in FIG. 7A taken through line BB shown in FIG. 7B. [Figure 9] FIG. 1 is a top view of a sample support used in the transmittance measurement method described herein. DETAILED DESCRIPTION OF THE INVENTION

[0003] definition For purposes herein, the following terms have the following meanings:

[0004] An "aperture" is an opening of any xy planar shape profile that is intentionally formed, punched, or cut along the z-direction completely through a layer to provide a z-directional passageway through the layer.

[0005] "Lateral direction," 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 of the upper parts of the wearer's legs adjacent the torso when the pad is normally worn and the wearer is in a normal, upright, standing position. The "width" dimension of any component or feature of an article, such as a feminine hygiene pad, is measured along the lateral direction. When the article or a component thereof is placed 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 unfolded and placed flat on a horizontal plane, "lateral" refers to the direction perpendicular to the longitudinal direction and parallel to the horizontal plane. With respect to an absorbent article, the "x-direction" is also the lateral direction.

[0006] The "lateral axis" of an absorbent article, such as a feminine hygiene pad or component thereof, is the horizontal line that lies in the xy plane and equally divides the length of the pad or component when the pad or component is laid flat on a horizontal surface. The transverse axis is perpendicular to the longitudinal axis.

[0007] "Longitudinal" refers to the direction perpendicular to the lateral direction with respect to an absorbent article, such as a feminine hygiene pad, or a component thereof. The "length" dimension of any component or feature of the article is measured along the longitudinal direction from its front extent to its rear extent. When an article, such as a feminine hygiene pad, or a component thereof, is placed flat on a horizontal surface, the "longitudinal" direction is perpendicular to the lateral direction with respect to the pad when worn, as defined above. With respect to an absorbent article, the "y-direction" is also the longitudinal direction.

[0008] The "longitudinal axis" of a feminine hygiene pad or component thereof is the longitudinal line that lies in the xy plane and equally divides the width of the pad or component when the pad is laid flat on a horizontal surface. The longitudinal axis is perpendicular to the horizontal axis.

[0009] With respect to an absorbent article, such as a feminine hygiene pad, or a component thereof, when placed flat on a horizontal surface, the "xy plane" means the horizontal surface of the article or component or any horizontal plane occupied by any layer.

[0010] With respect to an absorbent article, such as a feminine hygiene pad or component thereof, the "z-direction" is the direction perpendicular / orthogonal to the xy-plane when laid flat on a horizontal surface.

[0011] The terms "top," "bottom," "upper," "lower," "above," "below," "super-adjacent," "underlying," and similar terms characterizing relative vertical position, when used herein to refer to layers, components, or other features of an absorbent article, such as a feminine hygiene pad, are to be interpreted relative to the z-direction and the orientation of the article as it appears when placed flat on a horizontal surface with the surface facing the wearer positioned upward and the surface facing outwardly positioned downward.

[0012] 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 the component or structure that, in use, is located closer to the wearer than another feature of the component or structure. For example, a topsheet has a wearer-facing surface that is located closer to the wearer than the opposite, outward-facing surface of the topsheet.

[0013] With respect to absorbent articles, such as feminine hygiene pads, or components or structures thereof, "outwardly facing" is a relative positional term that refers to a feature of the component or structure that, in use, is positioned further from the wearer than another feature of the component or structure. For example, a topsheet has an outwardly facing surface that is positioned further from the wearer than an opposite, wearer-facing surface of the topsheet.

[0014] "Predominantly" and its aspects, when used to characterize the amount of weight, volume, surface area, etc. of an absorbent article or component thereof constituted by a composition, material, feature, etc., means that the majority of such weight, volume, surface area, etc. of the absorbent article or component thereof is constituted by the composition, material, feature, etc.

[0015] explanation 1, 2, and 3A, a feminine hygiene pad 10 can include a liquid-permeable topsheet 20, a liquid-impermeable backsheet 40, and an absorbent layer 30 disposed between the topsheet and the backsheet. The absorbent layer has a peripheral edge 35. In the area outside the peripheral edge 35, the topsheet and backsheet can be joined together in a laminated manner by any suitable mechanism, including, but not limited to, adhesive bonding, thermal bonding, pressure bonding, etc., thereby maintaining and holding the absorbent layer 30 in place between the topsheet 20 and the backsheet 40. The pad 10 can include opposed wing portions 25 extending laterally outward from the peripheral edge 35 with a width dimension relatively larger than that of the main portion of the pad. The wing portions 25 can be formed from profiled lateral extensions of the backsheet 25b (shown in FIG. 2) and / or the topsheet 25t (shown in FIG. 5). The outer surface of the backsheet, which forms the underside of the main and wing portions, may have a deposit of adhesive (not shown) thereon. Such adhesive deposits are provided to enable a user to adhere the pad to the inside of an undergarment in its crotch region, wrap the wing portions through and around the inner edges of the leg openings of the undergarment, and adhere them to the outer / underside of the undergarment in the crotch region, and can help provide auxiliary support and protect the leg edges of the undergarment from soiling. When pad 10 is packaged, the adhesive deposits may be covered by one or more sheets of release film or paper (not shown), which cover / shield the adhesive deposits from contact with other surfaces until the user is ready to remove the release film or paper and place the pad for use.

[0016] Top sheet The topsheet 20 is positioned adjacent the wearer-facing surface of the absorbent layer 30 and may be joined thereto and to the backsheet 40 by any suitable attaching or bonding method. The topsheet 20 and backsheet 40 may be joined directly to each other in a peripheral region outside the marginal edge 35 of the absorbent layer 30, or may be joined indirectly by being directly bonded to the wearer-facing and outward-facing surfaces, respectively, of the absorbent layer, or to additional optional layers included with the pad.

[0017] The topsheet 20 is formed of a single or laminated material that is suitably conformable, soft-feeling, and non-irritating to the wearer's skin. Suitable topsheet materials include liquid-permeable materials that are comfortable in contact with the wearer's skin and allow discharged menstrual fluid to rapidly penetrate therethrough. Suitable topsheets may be made from a variety of materials, such as suitable apertured liquid-permeable films, liquid-permeable nonwoven web materials, or combinations or laminates thereof.

[0018] In some non-limiting examples, the topsheet 20 may be formed from a polymeric film material having apertures therethrough to allow fluid to pass from the wearer-facing surface through the topsheet to the absorbent material below. Such liquid-permeable perforated films are known in the art. They provide a resilient, three-dimensional, woven structure. Such films are disclosed in detail in, for example, U.S. Patent Nos. 3,929,135, 4,151,240, 4,319,868, 4,324,426, 4,343,314, 4,591,523, 4,609,518, 4,629,643, 4,695,422, and WO 96 / 00548.

[0019] In another non-limiting example, the topsheet 20 can be formed from a liquid-permeable nonwoven web material. Examples of nonwoven web materials that may be suitable for use as the topsheet include fibrous materials made from natural fibers, modified natural fibers, synthetic fibers, or combinations thereof. Some suitable examples are described in U.S. Patent Nos. 4,950,264, 4,988,344, 4,988,345, 3,978,185, 7,785,690, 7,838,099, 5,792,404, and 5,665,452.

[0020] In some examples, the topsheet can include a tufted structure as described in U.S. Patent Nos. 8,728,049, 7,553,532, 7,172,801, 8,440,286, 7,648,752, and 7,410,683. The topsheet may have a pattern of individual hair-like fibrils as described in U.S. Patent Nos. 7,655,176 or 7,402,723. Additional examples of suitable topsheet materials include those described in U.S. Patent Nos. 8,614,365, 8,704,036, 6,025,535, and U.S. Patent Application Publication No. 2015 / 041640. Another suitable topsheet may be formed from a three-dimensional substrate as detailed in U.S. Patent Application Publication No. 2017 / 0258647. The topsheet may have one or more layers such as those described in U.S. Patent Application Publication Nos. 2016 / 0167334, 2016 / 0166443, and 2017 / 0258651.

[0021] As contemplated herein, the constituent nonwoven web material from which the topsheet 20 may be cut may be a nonwoven web material comprising or consisting essentially (by weight) of fibers spun from polymeric resins such as polyolefins, such as polypropylene, polyethylene and variants, blends, and bicomponent or multicomponent arrangements thereof.

[0022] Nonwoven webs can be formed by any suitable process capable of distributing and collecting spun fibers of variable length in a controlled manner on a moving forming belt to form a batt having a desired fiber distribution and a desired basis weight. Suitable processes include spunbonding and meltblowing. After collection, the batt can be treated to consolidate and bond the fibers into a coherent web by any suitable method, including calendering, calender thermal bonding, calender compression bonding, through-air bonding, etc. The consolidated web can be subjected to further processes, such as hydrostrengthening or hydroentangling, to increase the z-direction entanglement of the fibers and increase loft.

[0023] In some examples, nonwoven web materials are made by physically blending or mixing hydrophilic fibers of finite length (e.g., plant-based fibers such as cotton fibers, rayon fibers, etc.) with a stream of longer but indefinite length spun fibers spun from a polymer resin and placed on a forming belt to form a web, see, e.g., U.S. Pat. Nos. 8,017,534, 4,100,324, U.S. Patent Application Publication No. 2003 / 0200991, U.S. Pat. No. 5,110,324, U.S. Pat. No. 5,110,324, U.S. Patent Application Publication No. 2003 / 0200991, U.S. Pat. No. 5,110,324, U.S. Patent Application Publication No. 2003 / 0200991, U.S. Patent No. 5,110,324 ... No. 5,110,324, U.S. Patent No. 5,110,324, U.S. Patent No. 5,110,324, U.S. Patent No. 5,110,324, U.S. Patent No. 5,110,324, U.S. Patent No. 5 508,102, U.S. Patent Application Publication No. 2003 / 0211802, EP 0333228, WO 2009 / 10938, U.S. Patent Application Publication Nos. 2017 / 0000695, 2017 / 0002486, U.S. Patent No. 9,944,047, U.S. Patent Application Publication Nos. 2017 / 0022643 and 2018 / 0002848.

[0024] In the absence of material and / or process enhancements, monocomponent fibers spun from polymer resins generally tend to have relatively simple surface shapes, typically circular or generally elliptical cross-sections, and substantially no curling or crimping along their length. As a result, when the spun fibers are deposited and accumulated on a forming belt, calendered, and bonded (e.g., in a spunbond process), the resulting nonwoven web product will have a relatively low loft and a relatively flat appearance compared to webs of comparable basis weight formed from more complexly shaped, e.g., curled or crimped, fibers. Lower loft nonwoven webs may be perceived by some consumers as having a less pleasant feel and appearance, i.e., may be perceived as relatively less soft and luxurious than those with higher loft.

[0025] To add loft and increase web opacity without increasing basis weight (and material usage), the fibers used to form the web can be spun in a multicomponent, e.g., bicomponent, fiber configuration. The resin processing equipment and spinneret beam can be configured and the polymer resins selected to spin bicomponent fibers that crimp or curl as they leave the spinneret as a molten polymer stream and then cool and solidify into fibers. Known processes and polymer resin selections can be used to produce curled spun bicomponent fibers with side-by-side, eccentric core-sheath, or other non-coaxial polymer component cross-sectional configurations. In such non-coaxial configurations, one of the polymer components can be selected and / or formulated to have a different melting temperature and / or cooling shrinkage rate than the other polymer component. When cooled, the different properties and non-coaxial cross-sectional arrangement of the polymer components in the component cross-sections of the molten fiber stream cause the fibers to cool and shrink at different rates, imparting a curl to the fiber as it solidifies. Each polymer resin component may be a different polymer, a different form or variant of the same polymer, or a different blend thereof. More detailed disclosures of spinning curled or crimped bicomponent fibers and forming nonwoven webs thereof can be found, for example, in U.S. Pat. No. 8,501,646, U.S. EP 1988793, and U.S. Patent Application Publication No. 2007 / 0275622. In some examples, bicomponent fibers may have resin components that are primarily polypropylene-based, each formulated to impart different melting temperatures to each component. In some examples, bicomponent fibers may have one component that is primarily polypropylene-based and the other component that is primarily polyethylene-based. In some more specific examples, bicomponent fibers may be spun in an eccentric core-sheath component configuration, with a predominantly polypropylene-based component being the core component and a predominantly polyethylene-based component being the sheath component, where the polypropylene-based component may be desirable for its greater tensile strength and the polyethylene-based component may be desirable for its smoother, more silky surface feel, which helps to impart a silky feel to the fibers and nonwoven web material.It will be appreciated that other combinations of polyolefins and / or other spinnable thermoplastics can be selected for their different cooling shrinkage rates and other different qualities that affect the quality (including curl or crimp) and properties of the spun fiber in different ways.

[0026] By including a layer (which may be a relatively thin layer) of spun monocomponent fibers overlying a layer of bicomponent fibers on at least the wearer-facing side of the web, the bicomponent fiber component can be used to impart a perceptible soft, resilient loft to the topsheet web material while simultaneously preventing undesirable pilling. On a web-forming line having a moving forming belt, one or more beams configured to spin bicomponent fibers can be positioned upstream of a beam configured to spin monocomponent fibers. In such a configuration, a downstream monocomponent fiber spinning beam is positioned to deposit a layer of spun monocomponent fibers on the bicomponent fibers previously deposited on the moving belt. Alternatively, a monocomponent fiber spinning beam can be positioned upstream of the bicomponent fiber spinning beam. In either case, it is intended that the monocomponent fiber layer will serve as the wearer-facing layer of the topsheet of the final feminine hygiene pad product. After a batt of spun fibers is formed having layers of bicomponent and monocomponent fibers, the batt can be calendered in the nip between a pair of calendering rollers (one or both having a pattern of bonding protrusions) to form a pattern of fused bonds in the web by heat and / or compression that mirrors the pattern of bonding protrusions on the rollers. To maximize the likelihood of effective fused bonds at each bond site, it may be desirable for at least one polymeric resin component of the component cross-section of the bicomponent fiber and the polymeric resin component from which the monocomponent fiber is spun to be of similar chemical nature.

[0027] In some situations, it may be desirable for the roller with bonding protrusions to be the roller facing the monocomponent fiber layer in the nip, which may help to impart a quilted appearance to the monocomponent / wearer-facing layer to enhance the perception of soft loft of the topsheet. In other situations, it may be desirable for the roller with bonding protrusions to be the roller facing the bicomponent fiber layer in the nip, which may help to improve the cohesion of the web.

[0028] To preserve the soft, lofty appearance of the web material and avoid imparting an undesirable amount of stiffness to the web resulting from bonding, it may be desirable for the bonded area ((total bond area / total web area) x 100%) to be between 8 percent and 20 percent, or more preferably between 10 percent and 16 percent. The percentage of bonded area of ​​a bonded nonwoven web material is often understood to reflect the sum of the area of ​​the bonding surfaces (sometimes called "lands") of the bonding protrusions on the calender bonding roller used relative to the total circumferential area of ​​the active portion of the calender bonding roller having the pattern of bonding protrusions. The bonded area is often specified in drawings used to depict the bonding protrusion pattern and describe the dimensions for manufacturing the bonding roller, or can be calculated based on the dimensions and numerical density of the bonding protrusions / roller surface area reflected in such drawings.

[0029] To ensure that fluid contacting the top (wearer-facing) surface of the hydrophilic topsheet can be suitably and rapidly wicked in the z-direction to the bottom (outward-facing) surface of the topsheet, where it can be drawn into the absorbent layer, it can be important to ensure that the nonwoven web material forming the topsheet has an appropriate weight / volume density, thereby reflecting the presence of suitable gap channels within and between the constituent fibers through which fluid can migrate within the nonwoven material. Nonwovens with fibers that are too tightly consolidated will have an insufficient number and volume of gap channels, and the nonwoven will hinder rather than promote rapid z-direction fluid movement. In contrast, nonwovens with fibers that are not sufficiently consolidated to provide sufficient fiber-to-fiber contact and / or sufficiently small gap channels may provide insufficient potential for wicking in the z-direction by capillary action. To balance the requirements for web loft, opacity, and mechanical strength on the one hand, and the caliper and fiber count / web density limitations for rapid z-direction fluid transport on the other, bicomponent / monocomponent fiber web combinations may be desirably manufactured with a basis weight of 17 gsm (grams per square meter) to 33 gsm, or more preferably 21 gsm to 29 gsm. To ensure suitable rapid z-direction wicking, it may be preferable for the web to be manufactured with a caliper of 0.008 mm to 0.014 mm per unit basis weight, expressed in gsm. For example, a 25 gsm web may be preferably manufactured with a caliper of 0.20 mm (0.008 mm x 25 mm) to 0.35 mm (0.014 mm x 25 mm). For purposes of this specification, the caliper of a nonwoven web is measured using the dry caliper measurement method described below. It will be understood that the caliper can be adjusted by the degree of compression applied to the web in calendering, the density and bond area of ​​the bond pattern used, the amount of curl or crimp imparted to the bicomponent fibers, etc. The monocomponent fiber layer (the layer facing the wearer) may comprise 10 percent to 70 percent of the total basis weight of the web, more preferably 20 percent to 50 percent, and even more preferably 25 percent to 45 percent.

[0030] As mentioned above, forming a nonwoven web material from spun fibers containing curled bicomponent fibers can help increase the opacity of the web compared to a spunbond web formed solely from monocomponent fibers. This is believed to be the result of increased light scattering and diffusion due to greater fiber shape complexity and greater web loft. Higher opacity has been found to be beneficial for the purposes contemplated herein, as it increases the hiding power of topsheets formed from the web material. In addition to incorporating bicomponent fibers, manufacturers can also increase the opacity of the web material by including a whitening or opacifying additive with the monocomponent fibers and / or the resin from which the bicomponent fibers are spun. In some specific examples, manufacturers can include titanium dioxide opacifier / whitening agent in an amount of 1 weight percent, 2 weight percent, 3 weight percent, 4 weight percent, or even 5 weight percent or less of the resin for any one, two, or all of the individual bicomponent and monocomponent fiber components. In order to balance the hiding power of the web materials described herein with the constraints of basis weight and caliper, it may be desirable to adjust the basis weight and component resin formulation (including opacifying additives in the range deemed useful) to achieve an opacity level of the nonwoven web material of 30 percent to 42 percent as measured by the opacity measurement method described below.

[0031] Many commercially available thermoplastic resins that may be desirable for processing and spinning into bicomponent fibers are typically hydrophobic. Such resins include polyolefins such as polypropylene and polyethylene. Nonwoven web materials formed from such fibers also become hydrophobic and therefore cannot readily absorb or wick aqueous fluids, such as menstrual fluid. Therefore, when such resins are used, additional measures must be included to render the fibers and / or nonwoven web hydrophilic. In some instances, a suitable surfactant can be applied to the nonwoven web after its formation. In a more specific example, a suitable surfactant finish used may be SILASTOL PHP 26, a product of Schill+Seilacher GmbH, Boblingen, Germany. The finish can be applied to the web using any suitable method, such as by a kiss roll coater. The finish can be applied in an amount suitable to impart a desired level of hydrophilicity to the nonwoven web, which can help impart a desired level of capillary absorption / desorption pressure to the web. In a particular example, the finish coating of SILASTOL PHP 26 may be applied in an amount sufficient to constitute between 0.30 percent and 0.60 percent, more preferably between 0.40 percent and 0.50 percent, by weight of surfactant of the basis weight of the nonwoven web material after drying.

[0032] Absorbency and wicking performance can also vary depending on, and can be influenced by, how the web is further processed. Factors such as the level of compaction (i.e., densification) of the fiber mass in the edge structure and the orientation of the individual fibers within the edge structure can affect absorbency and wicking performance.

[0033] Thus, combining the objectives contemplated herein with the provision of suitable basis weight, density, and / or caliper discussed above, it may be desirable for nonwoven web materials formed partially or substantially entirely of fibers spun from thermoplastic polymer resins and used to make topsheets to be formed via a nonwoven web manufacturing process in which a significant portion of the fibers are imparted with a directional orientation that includes some z-direction orientation, rather than an orientation that is primarily forced along the machine direction or xy plane of formation of the web structure. Any suitable process for distributing and laying down fibers in a batt on a horizontal forming belt (e.g., by a spunbonding process) can be followed by additional process steps that force some or a portion of the fibers to reorient in the z-direction. Suitable process steps may include needlepunching and hydroentanglement or hydrostrengthening. Hydroentanglement or hydrostrengthening, in which an array of fine, high-velocity water jets is directed at the batt as it is conveyed past the water jets, may be desirable because of its effectiveness in reorienting the fiber length while reducing fiber breakage and reducing the formation of fiber strings and surface fuzz (free fiber ends extending from the surface of the web). Vacuum water removal systems (in which air is drawn through the web in the z-direction into a pattern of orifices or pores on a vacuum drum or belt conveying the batt, pulling the jetted water along with the air) may be desirable because they tend to form, add, open, and / or open small z-direction passages in the fiber matrix of the web, approximately in the pattern of orifices or pores. Without intending to be bound by theory, it is believed that the z-direction oriented fiber portions and z-direction passages increase the web's ability and tendency to wick aqueous fluids in the z-direction. In a topsheet, this would mean that the material may be able to wick fluid from the wearer-facing surface of the topsheet to the outward-facing surface of the topsheet, i.e., downward toward the absorbent layer underneath, thereby wicking less fluid along the xy plane (causing stains from the expelled fluid to spread laterally and / or longitudinally).

[0034] absorbent layer In some examples, the absorbent layer 30 may be formed from or may include a layer of absorbent open-cell foam material. In some examples, the foam material may include at least first and second sub-layers 30a, 30b (FIG. 4) of absorbent open-cell foam material, the sub-layers being associated with and in direct face-to-face contact with one another. In such examples, the wearer-facing sub-layer 30a may be a relatively larger-cell foam material and the outward-facing sub-layer 30b may be a relatively smaller-cell foam material, for purposes described in more detail below.

[0035] The open-cell foam material may be a foam material produced by polymerization of the continuous oil phase of a water-in-oil high internal phase emulsion ("HIPE").

[0036] Water-in-oil HIPEs have two phases. One phase is a continuous oil phase containing the monomers to be polymerized and an emulsifier that helps stabilize the HIPE. The oil phase may also contain one or more photoinitiators. The monomer component may be present in an amount of about 80% to about 99% by weight of the oil phase, and in certain examples, about 85% to about 95% by weight. An emulsifier component that is soluble in the oil phase and suitable for forming a stable water-in-oil emulsion may be present in the oil phase in an amount of about 1% to about 20% by weight of the oil phase. The emulsion may be formed at an emulsification temperature of about 20°C to about 130°C, and in certain examples, about 50°C to about 100°C.

[0037] Typically, the monomer may be present in an amount of about 20% to about 97% by weight of the oil phase and may include at least one substantially water-insoluble monofunctional alkyl acrylate or alkyl methacrylate. For example, this type of monomer may include C4 to C18 alkyl acrylates and C2 to C18 methacrylates, such as ethylhexyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, isodecyl acrylate, tetradecyl acrylate, benzyl acrylate, nonylphenyl acrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, tetradecyl methacrylate, and octadecyl methacrylate.

[0038] The oil phase may also contain from about 2% to about 40% by weight of the oil phase, and in one specific example, from about 10% to about 30% by weight of a substantially water-insoluble multifunctional crosslinked alkyl acrylate or methacrylate. This crosslinking comonomer or crosslinking agent is added to impart strength and elasticity to the resulting HIPE foam. Examples of this type of crosslinking monomer include monomers containing two or more activated acrylate or methacrylate groups, or combinations thereof. Non-limiting examples of such groups include 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,12-dodecyl dimethacrylate, 1,14-tetradecanediol dimethacrylate, ethylene glycol dimethacrylate, neopentyl glycol diacrylate (2,2-dimethylpropanediol diacrylate), hexanediol acrylate methacrylate, glucose pentaacrylate, sorbitan pentaacrylate, and the like. Other examples of crosslinkers contain mixtures of acrylate and methacrylate moieties, such as ethylene glycol acrylate-methacrylate and neopentyl glycol acrylate-methacrylate. The ratio of methacrylate to acrylate groups in the mixed crosslinker can vary from 50:50 to any other ratio as desired.

[0039] An optional third substantially water-insoluble comonomer can be added to the oil phase in a weight percentage of about 0% to about 15% by weight of the oil phase, and in certain instances, about 2% to about 8% by weight, to modify the properties of the HIPE foam. In certain cases, a "toughening" monomer may be desired, imparting toughness to the resulting HIPE foam. These include monomers such as styrene, vinyl chloride, vinylidene chloride, isoprene, and chloroprene. Without being bound by theory, it is believed that such monomers help stabilize the HIPE during polymerization (also known as "curing"), resulting in a more homogeneous and better-formed HIPE foam with improved toughness, tensile strength, abrasion resistance, and the like. Monomers can also be added to impart flame retardancy, as disclosed, for example, in U.S. Pat. No. 6,160,028. Monomers can be added to impart color (e.g., vinylferrocene), fluorescent properties, radiation resistance, radiation opacity (e.g., lead tetraacrylate), charge dispersion, reflect incident infrared light, absorb radio waves, wet the surface of the HIPE foam struts or cell walls, or any other desired property in the HIPE foam. In some cases, these additional monomers may slow the overall conversion process of the HIPE to a HIPE foam, but this tradeoff is necessary if the desired properties are to be imparted. Therefore, such monomers can also be used to slow down the polymerization rate of the HIPE. Examples of such monomers include styrene and vinyl chloride.

[0040] The oil phase may further contain an emulsifier to stabilize the HIPE. Examples of emulsifiers used in HIPEs include: (a) sorbitan monoesters of branched C16 to C24 fatty acids; straight-chain unsaturated C16 to C22 fatty acids; and straight-chain saturated C12 to C14 fatty acids, such as sorbitan monooleate, sorbitan monomyristate, and sorbitan monoester, sorbitan monolaurate, diglycerol monooleate (DGMO), polyglycerol monoisostearate (PGMIS), and polyglycerol monomyristate (PGMIS). monomyristate (PGMM); (b) polyglycerol monoesters of branched C16-C24 fatty acids, linear unsaturated C16-C22 fatty acids, or linear saturated C12-C14 fatty acids, such as diglycerol monooleate (e.g., diglycerol monoester of C18:1 fatty acid), diglycerol monomyristate, diglycerol monoisostearate, and diglycerol monoester; (c) diglycerol monoaliphatic ethers of branched C16-C24 alcohols, linear unsaturated C16-C22 alcohols, and linear saturated C12-C14 alcohols, as well as mixtures of these emulsifiers. See U.S. Patent Nos. 5,287,207 and 5,500,451. Another emulsifier that can be used is polyglycerol succinate (PGS), which is formed from alkyl succinate, glycerol, and triglycerol.

[0041] Such emulsifiers, and combinations thereof, may be added to the oil phase such that they comprise from about 1% to about 20%, in certain instances from about 2% to about 15%, and in certain other instances from about 3% to about 12% by weight of the oil phase. In certain examples, co-emulsifiers may also be used to provide further control of bubble size, bubble size distribution, and emulsion stability, especially at higher temperatures, e.g., above about 65° C. Examples of the co-emulsifier include phosphatidylcholine and phosphatidylcholine-containing compositions, aliphatic betaine, long-chain C12 to C22 divalent aliphatic quaternary ammonium salts, short-chain C1 to C4 divalent aliphatic quaternary ammonium salts, long-chain C12 to C22 dialkoyl(alkenoyl)-2-hydroxyethyl, short-chain C1 to C4 divalent aliphatic quaternary ammonium salts, long-chain C12 to C22 divalent aliphatic imidazolinium quaternary ammonium salts, short-chain C1 to C4 divalent aliphatic imidazolinium quaternary ammonium salts, long-chain C12 to C22 monovalent aliphatic benzyl quaternary ammonium salts, long-chain C12 to C22 dialkoyl(alkenoyl)-2-aminoethyl, short-chain C1 to C4 monovalent aliphatic benzyl quaternary ammonium salts, and short-chain C1 to C4 monohydroxy aliphatic quaternary ammonium salts. In a particular example, ditallow dimethyl ammonium methyl sulfate (DTDMAMS) may be used as a co-emulsifier.

[0042] The optional photoinitiator may comprise from about 0.05% to about 10% by weight of the oil phase, and in some examples, from about 0.2% to about 10% by weight. Small amounts of photoinitiator can allow better light penetration into the HIPE foam, thereby resulting in polymerization deeper into the HIPE foam. However, if polymerization is carried out in an oxygen-containing environment, it may be desirable to have sufficient photoinitiator present to initiate polymerization and overcome oxygen inhibition. Photoinitiators can respond rapidly and efficiently to a light source with the generation of radicals, cations, and other species capable of initiating a polymerization reaction. Photoinitiators selected for use in forming foams within the contemplated scope of the present disclosure can absorb ultraviolet radiation at wavelengths from about 200 nanometers (nm) to about 800 nm, and in certain examples, from about 250 nm to about 450 nm. When a photoinitiator is present in the oil phase, suitable types of oil-soluble photoinitiators include benzil ketals, α-hydroxyalkylphenones, α-aminoalkylphenones, and acylphosphine oxides.Examples of photoinitiators include 2,4,6-[trimethylbenzoyldiphosphine]oxide in combination with 2-hydroxy-2-methyl-1-phenylpropan-1-one (a 50:50 blend of the two is sold as DAROCUR 4265 by Ciba Specialty Chemicals, Ludwigshafen, Germany); benzil dimethyl ketal (sold as IRGACURE 651 by Ciba Geigy); α-,α-dimethoxy-α-hydroxyacetophenone (sold as DAROCUR 1173 by Ciba Specialty Chemicals); 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one (sold as IRGACURE 907 by Ciba Specialty Chemicals); 1-hydroxycyclohexyl-phenyl ketone (sold as IRGACURE 907 by Ciba Specialty Chemicals); bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (sold as IRGACURE 819 by Ciba Specialty Chemicals); diethoxyacetophenone, and 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-methylpropyl)ketone (sold as IRGACURE 2959 by Ciba Specialty Chemicals); and oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] (sold as ESACURE KIP EM by Lamberti spa, Gallarate, Italy).

[0043] The dispersed aqueous phase of the HIPE comprises water and may also comprise one or more components, such as an initiator, a photoinitiator, or an electrolyte, which in certain instances are at least partially water soluble.

[0044] One component contained in the aqueous phase may be a water-soluble electrolyte. The aqueous phase may contain from about 0.2% to about 40% by weight of the water-soluble electrolyte, and in certain examples, from about 2% to about 20% by weight of the water-soluble electrolyte. The electrolyte minimizes the tendency of primarily oil-soluble monomers, comonomers, and crosslinkers to dissolve in the aqueous phase. Examples of electrolytes include chlorides or sulfides of alkaline earth metals such as calcium or magnesium, and chlorides or sulfides of alkaline earth metals such as sodium. Such electrolytes may include buffers for controlling pH during polymerization, including inorganic counterions such as phosphate, borate, and carbonate, and mixtures thereof. Water-soluble monomers may also be used in the aqueous phase, examples of which include acrylic acid and vinyl acetate.

[0045] Another component that can be included in the aqueous phase is a water-soluble free radical initiator. The initiator can be present in an amount of up to about 20 mole percent based on the total moles of polymerizable monomer present in the oil phase. In certain examples, the initiator can be included in the oil phase in an amount of about 0.001 to about 10 mole percent based on the total moles of polymerizable monomer. Suitable initiators include ammonium persulfate, sodium persulfate, potassium persulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine) dihydrochloride, azo initiators, redox couples such as persulfate-bisulfate, persulfate-ascorbic acid, and other suitable redox initiators. In certain examples, the addition of the initiator to the monomer phase can be performed near the end of the emulsification process or immediately after emulsification to reduce the possibility of premature polymerization, which could interfere with the emulsion system.

[0046] The photoinitiator contained in the aqueous phase may be at least partially water-soluble and may comprise from about 0.05% to about 10% by weight of the oil phase, and in certain instances, from about 0.2% to about 10% by weight. Small amounts of photoinitiator can allow better light penetration into the HIPE foam, thereby resulting in polymerization deeper into the HIPE foam. However, if polymerization is carried out in an oxygen-containing environment, sufficient photoinitiator should be present to initiate polymerization and overcome oxygen inhibition. The photoinitiator can respond rapidly and efficiently to a light source with the generation of radicals, cations, and other species capable of initiating a polymerization reaction. Photoinitiators for use in foam formation within the contemplated scope of the present disclosure can absorb ultraviolet radiation at wavelengths from about 200 nanometers (nm) to about 800 nm, in certain instances from about 200 nm to about 350 nm, and in certain instances from about 350 nm to about 450 nm. When the photoinitiator is contained in the aqueous phase, suitable types of water-soluble photoinitiators can include benzophenones, benzils, and thioxanthones. Examples of photoinitiators include 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride; 2,2'-azobis[2-(2-imidazolin-2-yl)propane]disulfate dehydrate; 2,2'-azobis(1-imino-1-pyrrolidino-2-ethylpropane)dihydrochloride; 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; 2,2'-azobis(2-methylpropionamidine)dihydrochloride; 2,2'-dicarboxymethoxydibenzalacetone, 4,4'-dicarboxymethoxydibenzalacetone, 4,4'-dicarboxymethoxydibenzalcyclohexanone, 4-dimethylamino-4'-carboxymethoxydibenzalacetone; and 4,4'-disulfoxymethoxydibenzalacetone. Other suitable photoinitiators that can be used are described in US Pat. No. 4,824,765.

[0047] In addition to the above-mentioned components, other components may be included in either the water phase or the oil phase of the HIPE. Examples include antioxidants such as hindered phenols and hindered amine light stabilizers; plasticizers such as dioctyl phthalate and dinonyl sebacate; flame retardants such as halogenated hydrocarbons, phosphates, borates, inorganic salts such as antimony trioxide, ammonium phosphate, or magnesium hydroxide; dyes and pigments; fluorescent agents; filler particles such as starch, titanium dioxide, carbon black, or calcium carbonate; fibers; chain transfer agents; odor absorbers such as activated carbon particulates; dissolved polymers; dissolved oligomers; and the like.

[0048] HIPE foams are produced from the polymerization of monomers comprising the continuous oil phase of the HIPE. In certain instances, a HIPE foam layer may have one or more sublayers and may be either a homogeneous or heterogeneous open-cell polymeric foam. Homogeneity and heterogeneity refer to different layers within the same HIPE foam, which are similar in the case of homogeneous HIPE foams and different in the case of heterogeneous HIPE foams. Heterogeneous HIPE foams may contain at least two different sublayers that differ in chemical composition, physical properties, or both. For example, these sublayers may differ in one or more of foam density, polymer composition, specific surface area, or pore size (also called cell size). For example, in HIPE foams that differ in pore size, the average pore size of each sublayer may differ by at least about 20%, in certain instances by at least about 35%, and in still other instances by at least about 50%. In another example, where the difference between sublayers of a HIPE foam layer is with respect to density, the densities of the layers may differ by at least about 20%, in certain instances by at least about 35%, and in yet other instances by at least about 50%. For example, if one layer of HIPE foam has a density of 0.020 g / cc, another layer may have a density of at least about 0.024 g / cc or less than 0.016 g / cc, in certain instances by at least about 0.027 g / cc or less than about 0.013 g / cc, and in still other instances by at least about 0.030 g / cc or less than about 0.010 g / cc. Where the difference between layers is with respect to the chemical composition of the HIPE or HIPE foam, the difference may reflect a difference in the relative amount of at least one monomer component, for example, by at least about 20%, in certain instances by at least about 35%, and in further instances by at least about 50%. For example, if one sublayer of a HIPE or HIPE foam is comprised of about 10% styrene in its formulation, another sublayer of the HIPE or HIPE foam may be comprised of at least about 12%, and in certain instances, at least about 15%.

[0049] A HIPE foam layer structured with distinct sublayers formed from different HIPEs can provide a HIPE foam layer with a range of desirable performance characteristics. For example, a HIPE foam layer comprising first and second foam sublayers, where the first foam sublayer has a relatively larger pore or cell size than the second foam sublayer, can absorb incoming fluids more quickly than the second sublayer when used in an absorbent article. For example, when a HIPE foam layer is used to form the absorbent layer of a feminine hygiene pad, the first foam sublayer can be layered on top of a second foam sublayer having a relatively smaller pore size than the first foam sublayer. The smaller pore size exerts greater capillary pressure, drawing acquired fluids from the first foam sublayer and restoring the first foam sublayer's ability to acquire more fluid from above. The pore size of the HIPE foam can range from 1 to 200 μm, and in certain instances, can be less than 100 μm. A HIPE foam layer of the present disclosure having two major parallel surfaces may be about 0.5 to about 10 mm thick, and in certain instances, about 2 to about 10 mm thick. The desired thickness of the HIPE foam layer will depend on the material used to form the HIPE foam layer, the rate at which the HIPE is deposited onto the belt, and the intended use of the resulting HIPE foam layer.

[0050] The HIPE foam layers of the present disclosure are relatively open-celled. This refers to the individual cells or pores of the HIPE foam layer that are in substantially uninterrupted communication with adjacent cells. The cells of such substantially open-celled HIPE foam structures have intracellular openings or windows large enough to allow rapid fluid transfer from one cell to another within the HIPE foam structure. For purposes of this disclosure, a HIPE foam is considered "open-celled" if at least about 80% of the cells in the HIPE foam that are at least 1 μm in size are in fluid communication with at least one adjacent cell.

[0051] In addition to being open-celled, in certain instances, the HIPE foam is adapted to be sufficiently hydrophilic to allow the HIPE foam to absorb aqueous liquids. In some instances, the interior surface of the HIPE foam may be rendered hydrophilic by residual hydrophilizing surfactants or salts remaining in the HIPE foam after polymerization, by selected post-polymerization HIPE foam treatment procedures (described below), or a combination of both.

[0052] In certain instances, for example, when used to form an absorbent layer in a feminine hygiene pad, a HIPE foam layer can be flexible and exhibit an appropriate glass transition temperature (Tg). Tg represents the midpoint of the transition between the glassy and rubbery states of a polymer. Generally, HIPE foams with a Tg higher than the use temperature may be strong, but also relatively stiff and potentially prone to fracture (brittle). In certain instances, regions of the HIPE foam of the present disclosure that exhibit either a relatively high Tg or excessive brittleness will be discontinuous. These discontinuous regions also generally exhibit high strength and can be prepared at low densities without compromising the overall strength of the HIPE foam.

[0053] HIPE foams intended for applications requiring flexibility should include at least one continuous region having the lowest possible Tg, so long as the HIPE foam as a whole has acceptable strength at the temperatures in use. In certain instances, the Tg of this region will be less than about 40°C for foams used at about ambient temperature conditions, and in other instances, the Tg will be less than about 30°C. For HIPE foams used in applications where the use temperature is higher or lower than ambient temperatures, the Tg of the continuous region may be less than 10°C higher than the use temperature, in certain instances, the same as the use temperature, and in further instances, about 10°C lower than the use temperature if flexibility is desired. Thus, monomers are selected to provide the corresponding polymer with the lowest possible Tg.

[0054] HIPE foams useful for forming absorbent layers and / or sublayers within the contemplated scope of the present disclosure, as well as methods for their manufacture, include those disclosed in U.S. Pat. Nos. 10,045,890, 9,056,412, 8,629,192, 8,257,787, 7,393,878, 6,551,295, 6,525,106, 6,550,960, 6,406,64 ...51,295, 6,525,106, 6,550,960, 6,406,648, 6,551,295, 6,551,295, 6,525,106, 6,550,960, 6,551,295, 6,551,295, 6,551,295, 6,525,106, 6,550,960, 6,551,295, 6,551,295, 6,551,295, 6,551,295, 6,551,295, 6,551,295, 6,551,295 No. 6,376,565, No. 6,372,953, No. 6,369,121, No. 6,365,642, No. 6,207,724, No. 6,204,298, No. 6,158,144, No. 6,107,538, No. 6,107,538, No. No. 6,107,356, No. 6,083,211, No. 6,013,589, No. 5,899,893, No. 5,873,869, No. 5,863,958, No. 5,849,805, No. 5,827,909, No. 5,8 No. 27,253, No. 5,817,704, No. 5,817,081, No. 5,795,921, No. 5,741,581, No. 5,652,194, No. 5,650,222, No. 5,632,737, No. 5,563 ,179, No. 5,550,167, No. 5,500,451, No. 5,387,207, No. 5,352,711, No. 5,397,316, No. 5,331,015, No. 5,292,777, No. 5,268,22 Nos. 4, 5,260,345, 5,250,576, 5,149,720, 5,147,345, and U.S. Patent Application Publication Nos. 2005 / 0197414, 2005 / 0197415, 2011 / 0160326, 2011 / 0159135, 2011 / 0159206, 2011 / 0160321, and 2011 / 0160689.

[0055] Absorbent Layer Aperture 1, 2, and 3A, the foam-formed absorbent layer 30 may include one or more patterns of apertures 31, 32, including at least a first pattern disposed within an expected drainage area 60. As identified for purposes herein, the drainage area 60 is aligned with (but not necessarily centered longitudinally about) the pad's transverse axis 200, is substantially centered about the pad's longitudinal axis 100, and has an elliptical outline with a major longitudinal axis 5 cm long and a minor transverse axis 2.5 cm wide. The apertures 31, 32 may be punched, cut, or otherwise formed throughout the entire z-depth of the foam absorbent layer. When the foam absorbent layer is placed in direct contact with the topsheet without an intervening acquisition layer formed of another material, as described herein, the apertures 31, 32 can function as a group of small reservoirs to accept, temporarily hold, and assist in the distribution of relatively small amounts of menstrual fluid during a rapid discharge until the foam has had sufficient time to distribute and absorb the fluid by capillary action. Alternatively, or in addition, the apertures can function as pathways to direct fluid accepted during a sudden discharge through the absorbent layer to the spacer layer below, as described herein, providing additional reservoir volume along with fluid distribution capabilities. In addition, such apertures can help reduce the bending stiffness of the absorbent layer 30, which can help increase pad comfort for the wearer. To provide pathways for easy fluid flow, the average diameter or other largest dimension should be between 2.0 mm and 4.0 mm, and the average x-y plane open area on the surface facing the wearer should be 3 mm. 2 ~13mm 2 , more preferably 2.5 mm to 3.5 mm, and the average xy plane open area on the surface facing the wearer is 5 mm 2 ~10mm 2A pattern of circular, oval, or stadium-shaped apertures in the absorbent layer 30, for example, may be included within the area occupied by the drainage region 60. For a good balance between providing a sufficient number of passageways without removing too much absorbent material (removing absorbent capacity) from the absorbent layer 30, the apertures in the drainage region 60 should be spaced apart from each other within 1 cm of the surface area of ​​the wearer-facing surface of the absorbent layer 30. 2 3.0 to 9.0 apertures per cm, preferably 1 cm 2 4.0 to 8.0 apertures per cm, or even more preferably 1 cm 2 It may be desirable to have a numerical density of 5.0 to 7.0 apertures per 100 mm. In selecting the appropriate average size, numerical density, and surface area occupied by the aperture pattern, manufacturers may wish to balance the desired reservoir or passageway volume with the need to keep the absorbent material in close proximity to and near the expected discharge location. Further details regarding such aperture configurations, along with examples of suitable absorbent layers, can be found in U.S. Patent No. 8,211,078.

[0056] As suggested in FIG. 3B, the pattern of apertures 30, 31 allows the pad and foam absorbent layer 30 to more easily accommodate sudden discharges of fluid, allowing it to pass quickly through the absorbent layer to the spacer layer, where it resides for the time necessary for the absorbent layer to soak up and absorb the fluid.

[0057] The interface between the topsheet and the absorbent layer In examples where the topsheet is formed from a hydrophilic and / or absorbent web material, unless the underlying material has an absorption capacity and absorption pressure higher than the topsheet's discharge pressure, and sufficient direct contact is maintained between the topsheet and the underlying absorbent layer to allow fluid to migrate directly from the fiber surface in the topsheet structure to the material surface in the underlying absorbent layer structure, so that the underlying absorbent layer cannot draw fluid from the topsheet, the topsheet material may tend to retain fluid on its wearer-facing and outward-facing surfaces and in the interstitial spaces between and along the fibers of the web material. Before the absorbent material is fully saturated, it will not release the absorbed fluid unless an adjacent material with a greater affinity for the fluid is in sufficient direct contact. Therefore, it is important to provide sufficient structure to maintain sufficient contact without impeding fluid transfer. No intervening layer or structure of material, or at least an intervening layer or structure of material less absorbent than the absorbent layer, should be interposed between the material of the topsheet 20 and the material of the absorbent layer 30, at least in the discharge region 60, more preferably over a majority of the wearer-facing surface area of ​​the absorbent layer 30, and even more preferably over the entire wearer-facing surface area of ​​the absorbent layer 30. This differs from the systems provided in many current feminine hygiene pads, which include a separate layer of fluid acquisition / distribution material between the topsheet and the absorbent material of the absorbent core.

[0058] In some examples, sufficient direct contact between the topsheet 20 and the absorbent layer 30 may be provided by deposits of adhesive between the topsheet and the absorbent layer that adhesively bond them in close proximity in the z-direction. The adhesive may be applied in a pattern or arrangement of adhesive deposits interspersed with areas where there is no adhesive (unbonded areas), such that the adhesive holds the two layers in close proximity in the z-direction while maintaining areas where there is no adhesive to impede z-direction fluid movement between the layers.

[0059] 1, 2, and 6A-6C, it may be desirable to position the drainage area 60 on the pad at a location that includes the intersection of the longitudinal axis 100 and the transverse axis 200 to ensure that the topsheet and absorbent layer are held in sufficient proximity in the z-direction, at least in the area of ​​the topsheet that is expected to receive fluid discharge. The drainage area 60 should be of sufficient size to ensure that it is below the expected drainage location when the pad is in use, but with reasonable variability in placement within the undergarment by the wearer. Thus, the drainage area should be at least 15 cm 2 , more preferably at least 30 cm 2 Even more preferably, it may be desirable for the drainage region to have an area that is at least half of the total wearer-facing surface area of ​​the absorbent layer. (Note: Figures 6A-6C are not presented herein as depictions of actual size or scale.)

[0060] To ensure that the topsheet 20 and the absorbent layer remain sufficiently close in the z-direction during use, it may be desirable that within any identifiable first point location 27 in the discharge region where the topsheet is bonded to the absorbent layer, there be a second point location where the topsheet is bonded to the absorbent layer within a 10 mm radius, more preferably a 6 mm radius, a 5 mm radius, a 4 mm radius, and even more preferably within a 3 mm radius r of the first point location. Referring to Figures 3A-3C, which show three non-limiting examples, it can be seen that various patterns or arrangements of bonds (via adhesive deposits 26 or other bonding mechanisms) may be employed to impart this feature. Within radius r of each point location 27, there are numerous additional point locations where bonds between the topsheet and absorbent layer are present in the illustrated examples.

[0061] A continuous deposit of adhesive can be applied to bond the topsheet and absorbent layer throughout the entire discharge region 60, although it will be understood that such a continuous deposit of adhesive may form a barrier to fluid transfer from the topsheet to the absorbent layer. Thus, in instances where the bonding mechanism is a deposit of adhesive, the deposit is preferably arranged in a discontinuous or intermittent pattern or configuration to form bonded areas interspersed with unbonded areas between the topsheet and absorbent layer. Additionally, when the absorbent layer is formed of an open-cell foam (such as the foams contemplated herein), it may be desirable for the selected adhesive not to bond to the absorbent layer via chemical, dispersive, or diffusion bonding with the foam layer at the adhesive deposition location, but rather to mechanically bond to the foam layer by flowing confinedly into the cells, at least partially assuming their shape, and solidifying at such location to form a mechanical interlock with the cell structure, thereby allowing the adhesive to hold the topsheet to the absorbent layer. Such adhesives may be preferred because they do not alter the molecular structure or composition of the foam material, potentially adversely affecting its fluid absorption properties or mechanical strength. In one example, a suitable adhesive for use with HIPE foam may be H1750 hot melt adhesive from Bostik (Wauwatosa, Wisconsin) (now a subsidiary of Arkema (Columbes, France)).

[0062] Non-porous topsheets for feminine hygiene pads formed from nonwoven web materials and containing or consisting primarily of hydrophilic fibers are known and have been included in some feminine hygiene products to date. (As used herein, a "non-porous" nonwoven topsheet is one whose majority of its surface area has not been subjected to any process that creates holes or an arrangement of holes that extend completely through the topsheet, with an average size (largest dimension) of more than 0.5 mm along the x-y plane prior to wetting of the topsheet.) While preferred by some consumers for their comfortable feel against the skin, other consumers dislike topsheets formed from hydrophilic nonwoven web materials because their substantial absorbency, i.e., capillary absorption and discharge pressure, results in the topsheet being resistant to drainage by conventionally included acquisition / distribution and absorbent layer structures. After menstrual discharge, a pad having such a topsheet superimposed on a conventional absorbent structure can feel like a wet cloth is being held in contact with the skin for an extended period of time, which many users find objectionable.

[0063] However, a nonporous hydrophilic fibrous topsheet directly superimposed in a sufficiently face-to-face proximity with a foam absorbent layer or other layer adapted / manufactured to have sufficient capillary absorption capacity to draw fluid from the topsheet, without any intervening less absorbent layer, and in combination with other structural features as described herein, will have the fluid substantially wicked away by the absorbent layer and restore a much drier feel to the skin after wicking. As described herein, a suitably constructed and manufactured HIPE foam absorbent layer, for example, will have a greater affinity for menstrual fluid than such a topsheet, thereby having the ability to wick fluid from the topsheet and keep the fluid away from the topsheet when the two are positioned and held in a sufficiently effective close contact with each other. If the absorbent layer has sufficient volume, it can perform this function over a reasonably suitable period of use of the pad.

[0064] Spacer Layer 1, 2, 3A, and 3B, it is contemplated herein to include a spacer layer 50. The primary purpose of the spacer layer is to provide a structure beneath the absorbent layer 30 that holds open a desired amount of unoccupied space (i.e., a reservoir) between the absorbent layer 30 and the backsheet 40, into which unabsorbed menstrual fluid can flow and reside temporarily for the time necessary for the absorbent layer 30 to effectively wick the fluid. The spacer layer 50 is preferably positioned beneath, rather than over, the absorbent layer 30 to help prevent unabsorbed fluid from rewetting the topsheet. Additionally, the absorbent layer 30 preferably includes apertures 31, 32, as described above, that penetrate the entire absorbent layer 30, i.e., from the wearer-facing surface to the outward-facing surface, to provide a path for unabsorbed fluid to rapidly migrate to the spacer layer.

[0065] It is contemplated herein that the spacer layer 50 may be formed entirely from, or alternatively may include, an open-cell foam having a composition different from that of the foam absorbent layer and an average cell size larger than that of the foam absorbent layer. In some examples, the spacer layer may be formed from or may include a layer of open-cell polyurethane foam.

[0066] It is also contemplated herein that the spacer layer 50 may be formed entirely of, or alternatively include, a nonwoven batt, web, or bundle (collectively, herein, "fiber assembly") formed of filaments or fibers (collectively, fibers).

[0067] If included, it may be desirable for such fibrous assemblies to be formed primarily, if not substantially entirely, from fibers or filaments spun from one or more thermoplastic polymer resins from a spinneret configured to produce fibers having a substantially circular cross-section. Such fibers or filaments are typically not absorbent, as they generally do not contain complex surface topography, pores, or internal spaces through which fluids can flow and be retained.

[0068] The thermoplastic resin may desirably include one or more of polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET). PET may be particularly desirable because fibers spun therefrom have a relatively higher stiffness per unit diameter or cross-sectional dimension than fibers spun from other polymers, which are in relatively abundant supply and cost-effective for purposes herein.

[0069] In some examples, it may be desirable for a majority of the fibers to be bicomponent fibers, and in some examples, it may be desirable for the bicomponent fibers to be crimped or curled. Crimped or curled bicomponent fibers can result from a combination of polymer fiber components with different melting temperatures and / or shrinkage upon cooling, arranged in a side-by-side or "pie-slice" component cross-sectional configuration, or from an eccentric component cross-section, e.g., an eccentric sheath-core configuration. Due to their shape, crimped or curled fibers impart loft and volume to the resulting nonwoven material, and thus their inclusion can increase the volume of open interfiber / void space within the material per unit caliper. Thus, in some examples, the spacer layer 50 may be formed from or include a fiber assembly that is primarily formed from or includes curled bicomponent fibers. In some examples, the components of the bicomponent fiber may be two different PE compositions. In some examples, the components may be PE and PP, and in some examples, the components may be PE and PET, e.g., a fiber having a PET core component and a PE sheath component. This particular combination allows the fiber assembly to be strengthened and / or stiffened to better retain volume / loft through inter-fiber thermal bonding, for example, through heating in an oven or hot air-through processing. PE's lower melting temperature allows the PE sheaths of adjacent fibers to fuse together without melting the PET core due to their higher melting temperature. This type of inter-fiber bonding can be achieved without compressing the fiber assembly, reducing loft / volume, as occurs with heat / compression localized spot bonding or calendar bonding.

[0070] In order to achieve a balance between stiffness and resilience to maintain loft and volume for softness and wearer comfort maintained by the pad as a whole, it may be desirable for the fiber components of the fiber assembly to have an average denier of 1 to 6, more preferably 1.5 to 5.5, and even more preferably 2 to 5.

[0071] It may be desirable for a majority, substantially all, or all of the fibers or filaments that may form the spacer layer 50 to be spun from an inherently hydrophilic material or, alternatively, treated to be hydrophilic as described above. The objective is to enable the spacer layer 50 to readily accept fluid moving downward through the apertures 31, 32 and wick or transport the fluid through and across the structure of the spacer layer, thereby distributing the fluid along the underside of the absorbent layer 30 to maximize its surface area exposure to the fluid and provide effective and efficient use of the absorbent layer. If the spacer layer were primarily composed of a material with a hydrophobic surface, the spacer layer may not readily accept or transport fluid exiting the apertures under the absorbent layer.

[0072] Based on the volume of the desired fluid reservoir space, the spacer layer 50 should be at least 1,000 mm 3 (For purposes herein, void volume is calculated by multiplying the wearer-facing surface area of ​​the spacer layer by its dry caliper and subtracting the mass of each polymer present in the spacer layer divided by its density.) Dry caliper is measured by the steps described in the Compression Recovery and Dry Caliper Measurement Method described below. However, to avoid imparting a level of caliper to the entire assembled product that may be objectionable to the wearer, it may be desirable for the dry caliper of the spacer layer to be 3.0 mm or less, more preferably 2.0 mm or less, even more preferably 1.5 mm or less, and more preferably 1.0 mm or less.

[0073] With respect to void volume and to ensure that the spacer layer 50 readily accommodates the eruptions of fluids from the apertures 30, 31, it may be desirable to fabricate the spacer layer to have a permeability above a minimum value. Generally, "permeability" reflects the amount of resistance a material offers to the pressurization / forcing or flow of liquid through it. A relatively high permeability reflects a relatively low resistance to fluid flow, while a relatively low permeability reflects a relatively high resistance to fluid flow. Two materials with the same void volume per unit total volume may have different permeabilities, with the permeability level of a material being influenced, in part, by the amount of solid material surface area through which fluid must pass to move through the material and the frictional resistance to fluid movement across the surface. Thus, for example, a first nonwoven web material composed of many smaller fibers will exhibit a lower permeability than a second nonwoven web material of the same basis weight and void volume composed of fibers of the same composition but with larger, fewer, larger-sized fibers because the second material has a smaller fiber surface area.

[0074] Thus, for purposes herein, it may be desirable for the spacer layer 50 to be manufactured to have a permeability of at least 1,000 darcy, preferably at least 3,000 darcy, more preferably at least 5,000 darcy, or between 1,000 darcy and 6,000 darcy, or other upper limit for the particular material used to construct the spacer layer. All subranges within this larger range are contemplated herein. For purposes herein, permeability is measured using the permeability measurement method described below. In one example, a nonwoven web material considered suitable for constructing the spacer layer for purposes herein is a carded staple fiber nonwoven web material having a basis weight of 15 gsm, a caliper of about 0.8 mm at 0.1 psi applied pressure in the z-direction, and the fibers have an average denier of 6 and are comprised of bicomponent fibers spun in a sheath-core configuration, with the sheath component formed from PE and the core component formed from PET in a weight ratio of about 50:50. This material was found to have a permeability of about 5,083 darcy.

[0075] Additionally, it may be desirable for the spacer layer 50 to be manufactured to have a minimum level of compression recovery. Compression recovery reflects the resiliency of a material and its relative ability to maintain its caliper and void volume after compression, such as may occur when a user / wearer sits on it. Good compression recovery may also be perceived by a user as being soft and cushiony. Compression recovery may be influenced by the selection of materials comprising the spacer layer. In some examples, when the spacer layer is constructed from a fibrous nonwoven web material, selecting a relatively elastic fiber component may help impart good compression recovery. For purposes herein, it may be desirable for the spacer layer to be manufactured to exhibit a compression recovery of at least 75 percent of its caliper, up to the limit of feasibility for the particular material selected to construct the spacer layer, in application of the compression recovery measurement method described herein.

[0076] Preferably, the spacer layer will underlie most, and more preferably all, of the outward-facing surface openings of the apertures 31, 32 present in the absorbent layer 30. This is to ensure that any unabsorbed fluid that drains through the apertures is captured by the spacer layer, rather than having a path into the open space between the topsheet and backsheet, which could increase the risk of rewetting the topsheet. At the same time, it may be preferable that the spacer layer not have any portion extending beyond the peripheral edges of the absorbent layer. This is to ensure that all of the wearer-facing surface of the spacer layer 50 faces the outward-facing surface of the absorbent layer 30, so that fluid within the spacer layer 50 can be more easily absorbed by the absorbent layer 30.

[0077] Thus, it may be desirable for the spacer layer 50 to have a perimeter that substantially coincides with the perimeter of the absorbent layer 30. However, keeping in mind that the foam absorbent layer 30 and the spacer layer 50 may be manufactured by substantially different manufacturing techniques, it may be desirable for the spacer layer 50 to have a perimeter that lies laterally and longitudinally within the perimeter of the absorbent layer 30. In the same example, for purposes of manufacturing efficiency, the spacer layer 50 may have a perimeter that is substantially rectangular, as suggested in Figures 2A, 2B, and 5. However, as also suggested in those figures, the spacer layer 50 may be sized, shaped, and positioned to completely underlie all of the apertures 31, 32 in / through the absorbent layer 30.

[0078] In particular, if the spacer layer 50 is given a size and surface area smaller than that of the absorbent layer 30, as suggested in the figures, it may be desirable to glue or bond the spacer layer in place to the absorbent layer to maintain the spacer layer in its intended position below the apertures. In some instances, the spacer layer 50 may be directly adhered to the underside (outward-facing side) of the absorbent layer 30. This can be done by a deposit or pattern of adhesive deposits disposed between the layers 30, 50. To ensure that the fluid passages provided by the apertures 31, 32 into the spacer layer 50 are not obstructed by such adhesive deposits at anticipated fluid evacuation locations, it may be desirable to place the adhesive primarily around the peripheral region 50p of the spacer layer, i.e., outside of the boundary 51 (shown in FIG. 5 ). The boundary 51 equally divides the distance of the peripheral edge of the spacer layer 30 from the intersection of the longitudinal axis 100 and the transverse axis 200.

[0079] Alternatively or additionally, the spacer layer 50 may be adhered to the backsheet 40 by an adhesive deposit or pattern of deposits disposed between the layers 50, 40. In this location, such adhesive would not impede fluid flow from the apertures 31, 32 into the spacer layer. On the other hand, adhering the spacer layer 50 directly to the absorbent layer 30 via an adhesive deposit, as described above, may help ensure that the layers remain in close proximity or surface-to-surface contact with shifting movements of the wearer's body, better ensuring that fluid can easily migrate from the apertures 31, 32 into the spacer layer.

[0080] back seat The backsheet 40 can be positioned below or adjacent to the outward-facing surface of the spacer layer 50 and can be joined to that surface by any suitable attachment method. For example, the backsheet 40 can be secured to the spacer layer 50 by a uniform continuous layer of adhesive, a patterned layer of adhesive, or an array of discrete lines, spirals, or dots of adhesive. Alternatively, the attachment method can include thermal bonding, pressure bonding, ultrasonic bonding, dynamic mechanical bonding, or any other suitable attachment mechanism, or a combination thereof. In other examples, it is contemplated that the absorbent layer 30 is not directly joined to the backsheet 40.

[0081] The backsheet 40 may be manufactured to be impervious to liquids (e.g., urine, menstrual fluid) under normal conditions of use of the feminine hygiene pads contemplated herein and may be manufactured from a plastic film, although other flexible, liquid-impermeable materials may also be used. The backsheet 40 may prevent, or at least substantially inhibit, fluids absorbed and contained within the absorbent layer 30 from leaking and reaching the wearer's articles of clothing, such as undergarments, outerwear, bedding, etc., that may come into contact with the pad 10. However, in some cases, the backsheet 40 may be constructed and / or adapted to be vapor permeable (i.e., the backsheet may be constructed to be breathable), while in other cases, the backsheet 40 may be constructed to be vapor impermeable (i.e., the backsheet may be constructed to be non-breathable). Thus, the backsheet 40 may comprise a polymeric film, such as a thermoplastic film of polyethylene or polypropylene. A suitable material for the backsheet 40 is, for example, a thermoplastic film having a thickness of about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mil). Any suitable liquid impervious backsheet material known in the art is contemplated herein.

[0082] Some suitable examples of backsheet materials are described in U.S. Patent Nos. 5,885,265, 4,342,314, and 4,463,045. Suitable single-layer breathable backsheets for use herein include those described in, for example, British Patent Nos. A2184389, A2184390, and A2184391, U.S. Patent Nos. 4,591,523, 3,989,867, and 3,156,242, International Publication No. WO 97 / 24097, and U.S. Patent Nos. 6,623,464, 6,664,439, and 6,436,508.

[0083] The backsheet may be constructed of two layers, a first layer comprising a vapor-permeable apertured formed film layer and a second layer comprising a breathable microporous film layer, as described in U.S. Patent No. 6,462,251. Other suitable examples of two-layer or multi-layer breathable backsheets for use herein include those described in U.S. Patent Nos. 3,881,489, 4,341,216, 4,713,068, 4,818,600, EP 203821, EP 710471, EP 710472, and EP 0793952.

[0084] Transmittance measurement method This method allows for the calculation of a material's permeability (in Darcy) through measurement of the downward movement of a test fluid through a test sample along the z-direction (vertical) over a range of downward heads, indicated by the decreasing height of the test fluid within the vessel. The decreasing height of the test fluid within the vessel is measured repeatedly over time during the procedure as the fluid passes through the test sample and drains out the bottom of the vessel. From the collected data, along with the relevant dimensions of the portion of the apparatus through which the fluid moves, the measured wet caliper of the test sample, constants related to gravity and the properties of the selected test fluid, flow rate, and permeability can be calculated. 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 two hours prior to testing.

[0085] Device Components Measurement device 600 and its components are shown in Figures 7A-9. Referring to Figure 7A, device 600 includes a cylindrical fluid container 601 including a cylindrical wall 601a having a fitted lid 602 and a base 603 sealingly fitted to the bottom of wall 601a to form fluid container 601; a fluid level sensor 606 fitted to and penetrating lid 602; a valve 607 housed within valve body 608; and a valve actuator 610 mechanically associated with the valve via linkage 609.

[0086] The cylindrical wall has an inside height Hfv to the bottom of the lid of 200 mm, an inside diameter of 3 7 / 8 inches (98.425 mm), a wall thickness of 3 / 8 inch (9.525 mm), and an outside diameter of 4 5 / 8 inches (117.48 mm). The lid 602 is preferably fitted to rest securely on top of the cylindrical wall, but should not be a tight fit, and is drilled with one or more vent holes (not shown) to prevent negative pressure / vacuum from building up within the fluid container as the test fluid is expelled from the fluid container. The purpose of the lid 602 is to hold and suspend the fluid height sensor 606 above the test fluid surface, not to seal the top of the container.

[0087] 7A, base 603 has flat, parallel upper and lower surfaces, the upper surface of which is sealingly attached to the bottom of wall 601 a. Base 603 is suitably shaped or machined to define a sample chamber therein having a cylindrical upper chamber portion 603 a, a cylindrical middle chamber portion 603 b, and a cylindrical lower chamber portion 603 c. The three cylindrical chamber portions are coaxial along the vertical / z direction.

[0088] The heights and inner diameters of the three chamber sections are as follows: Height Huc of the upper chamber portion 603a: 9.5 mm, Inner diameter Duc of upper chamber portion 603a: 40 mm, Height Hmc of the middle chamber portion 603b: 12.5 mm, Inner diameter Dmc of the middle chamber portion 603b: 30 mm, The height Hlc of the lower chamber portion 603c: 20 mm, and The inner diameter Dlc of the lower chamber portion 603a: 26 mm.

[0089] A valve body 608 having a valve 607 is attached to the underside of the base 603, below the lower open end of the lower chamber 603c. The valve 607 is configured to be rapidly actuated between a fully closed position and a fully open position, such that in the open position, the entire lower chamber portion 603c is open, allowing fluid to move freely downward therefrom without any restriction by the valve 607. The valve 607 may be a flat, horizontally sliding member having a circular opening port of at least 26.0 mm in diameter, which is moved linearly to a position below the lower chamber portion 603c upon actuation to the open position. Alternatively, the valve 607 and valve body 608 may have any other suitable configuration adapted to be rapidly actuated between a fully closed position and a fully open position, such that when in the fully open position, the valve does not present any obstruction to fluid flow downward and out of the lower open end of the lower chamber portion 603c. Valve 607 and actuator 610 are configured to actuate from a fully closed position to a fully open position, and vice versa, within 10 milliseconds of either movement. Actuator 610 may include a solenoid or any other suitable mechanism adapted for this purpose.

[0090] Cylindrical wall 601 a, lid 602, base 603, and optionally valve body 608 and valve 607 are fabricated and machined from polished clear cast acrylic plastic (poly(methyl methacrylate) (PMMA)) stock (known brands include, but are not limited to, PLEXIGLAS and LUCITE), which is available in a variety of precast tube, rod / bar, disc, sheet, and block forms from various suppliers of such materials, such as McMaster-Carr Supply Company (Elmhurst, Illinois). Depending on availability, tubing used to form wall 601 a can be selected with an inner diameter Dfv that varies slightly from the inner diameter Dfv specified herein. In such cases, it will be recognized that the corresponding value of the radius r of the fluid enclosure in the equation below should be changed to reflect the actual diameter Dfv of the tubing used.

[0091] The fluid height sensor 606 is an ultrasonic height sensor such as part #098-10060 ML series, airborne continuous transmitter with an accuracy of approximately +0.2 mm (TE Connectivity, Schaffhausen, Switzerland, and Berwyn, Pennsylvania, USA) or equivalent, interfaced to a computer running software capable of collecting fluid height versus time data throughout the test at a rate of 100 Hz. The fluid height sensor 606 continuously transmits a signal indicative of the height of the test fluid in the fluid container 601 during the measurement procedure.

[0092] The apparatus further includes a support structure, which may include a support platform 611 and height-adjustable legs 612, or any other suitable support structure, configured to stably hold the container and valve assembly above the collection container 613, with the longitudinal axis of the cylindrical wall 601a vertical / plumb and the bottom of the base 603 horizontal. If included, the support platform 611 must include an opening or otherwise be configured so as not to obstruct the bottom end of the lower chamber portion 603c or the fluid exit from the valve 607 and valve body 608.

[0093] The measurement device further includes a collection vessel 613 of any suitable shape, size, and material composition suitable for receiving and stably containing the entire volume of test fluid used in the method, and which easily fits beneath the support structure.

[0094] The measurement device further includes a sample weight 604, which is machined from stainless steel to the configuration and dimensions shown in Figures 8A-8C. A small radially inward protruding lip on the top of the sample weight 604 is included to provide a gripping feature to facilitate placement and removal of the sample weight 604 from the sample chamber.

[0095] The measurement apparatus further includes a sample support 605 having the configuration and dimensions shown in FIG. 9. The sample support 605 has a z-direction caliper (height when in place within the measurement apparatus in preparation for the measurement procedure) of 0.75 mm. Each of the concentric ring portions 605a and radial spoke portions 605b of the sample support 605 shown in FIG. 9 has an xy-plane width of 0.75 mm and a square cross-section. The sample support 605 is configured to support a test specimen 616 within the intermediate chamber portion 603b of the base 603. The sample support 605 may be cut or machined from any material of suitable strength and corrosion resistance, such as, for example, brass sheet stock.

[0096] It should be noted that the outer diameter of the sample support 605 and the inner diameter of the intermediate chamber portion 603b are both defined above to be 30.0 mm. The sample support 605 is disposed within the intermediate chamber 603b during the measurement procedure. It is therefore understood that either or both of the inner diameter of the intermediate chamber portion 603b and the outer diameter of the sample support 605 may require slight adjustment to provide a small but sufficient clearance to allow the sample support 605 to be conveniently inserted into and withdrawn from the intermediate chamber portion 603b.

[0097] Similarly, it should be noted that the outer diameter of the lower portion of sample weight 604 and the inner diameter of middle chamber portion 603b are both specified above to be 30.0 mm, and the outer diameter of the upper portion of sample weight 604 and the inner diameter of upper chamber portion 603a are both specified to be 40.0 mm. During a measurement procedure, the lower portion of sample weight 604 is disposed within middle chamber portion 603b, and the upper portion of sample weight 604 is disposed within upper chamber portion 603a. Accordingly, it will be understood that either or both of the inner diameter of middle chamber portion 603b and the outer diameter of the lower portion of sample weight 604, and either or both of the inner diameter of upper chamber portion 603a and the outer diameter of the upper portion of sample weight 604, may require slight adjustment to provide a small but sufficient clearance to allow sample weight 605 to be conveniently inserted into and withdrawn from middle chamber portion 603b.

[0098] The measurement device further includes a computer (not shown) with suitable software and interface devices configured to communicate with valve actuator 610 to open and close valve 607, and to receive and collect fluid height data from fluid height sensor 606 over time at a rate of 100 Hz. One skilled in the art will have sufficient knowledge and / or resources readily available to obtain the components and configure a system including a computer and software to perform the operations described herein.

[0099] Preparation of test fluids The test fluid used in this measurement method is an aqueous solution of sodium chloride (NaCl) at a concentration of 0.9% by weight.

[0100] The ingredients required for the preparation of saline test fluid include NaCl (reagent grade, CAS 7647-14-5) and deionized water. NaCl is available from any convenient source, for example, Sigma Aldrich item S9888.

[0101] The following preparation steps result in approximately 2 liters of 0.9 wt% NaCl test fluid: Add 18.0 g of NaCl to a 2 L Erlenmeyer flask, followed by 1982.0 g of deionized water. Stir until the NaCl is completely dissolved.

[0102] Measurement procedure To obtain the test sample for measurement, a single layer of the dry target material is laid flat on a horizontal work surface and a 30 mm diameter circular test sample is punched out from it. When selecting the location for sampling, avoid areas of the material that have folds, wrinkles, or tears.

[0103] If the target material is a layer component of an absorbent article (e.g., a feminine hygiene pad), such as a topsheet or absorbent layer component, obtain a representative sample of the target material that is not incorporated into the absorbent article. Alternatively, if only a fully manufactured absorbent article is available as the source of the target material, from that example, separate the target layer component from the article without stretching or damaging it. Once the target layer component is removed from the article, punch out the test sample as described above. Precondition the test sample for 2 hours at 23°C ± 2°C and 50% ± 2% relative humidity before testing.

[0104] 7B, with fluid valve 607 in the closed position, sample support 605 is inserted into middle chamber portion 603b so that it lies horizontally / flat on the lower circumferential lip of middle chamber portion 603b. Using tweezers, test sample 616 is gently placed on top of sample support 605 and laid flat to prevent wrinkles. Next, sample weight 604 is gently placed over / onto test sample 616 so that the lower portion of sample weight 604 is inserted into middle chamber portion 603b and rests on the test sample around its periphery, and the upper portion of sample weight 604 is nested within upper chamber portion 603a.

[0105] Next, the pre-prepared test solution is slowly added to the fluid container 601 until it reaches an initial fluid surface 614 height Hi, 150 mm above the top surface of the test sample 616 .

[0106] Allow the test sample 616 to equilibrate in the filled sample chamber for approximately 60 seconds to ensure that no air bubbles are present on the surface of the test fluid or the surface of the test sample. If air bubbles are present on the fluid surface, use a clean instrument to remove or pop them. If air bubbles are present on the top surface of the test sample 616, gently remove the bubbles using a clean, round-tipped laboratory stirrer, taking care not to remove the fibers (if the test sample is fibrous) or stretch or damage the test sample.

[0107] The fluid height sensor 606 is secured to the lid 602, which is then positioned and fitted onto the cylindrical wall 601a. ​​Adjust the position of the fluid height sensor 606, if necessary, before the start of the test to prevent the fluid height sensor 606 from contacting the starting surface of the test fluid. Initially, the lower tip of the sensor 606 should be approximately 170 mm from the top surface of the test sample 616.

[0108] A collection vessel 613 is placed below the valve 607 .

[0109] Referring now to FIG. 7C , to begin the measurement, valves 607 are simultaneously opened, and the acquisition of decreasing fluid height Hd and time data begins at a data acquisition rate of 100 Hz, in increments of 0.01 mm and 0.01 seconds, respectively. The test fluid flows under gravity through the sample chamber, through the test specimen 616, sample support 605, and open valve 607, and into the collection container 613, causing the test fluid surface 614 to descend and the collected fluid surface 615 to rise. Height sensor 606 senses and transmits data regarding the height of test fluid surface 614 over time at a specified sensing frequency. The measurement ends when no more test fluid exits the valve, or after 1,000 seconds have elapsed, whichever occurs first, and valve 607 is closed. The lid 602 is removed. The sample weight 604 is lifted out of the sample chamber, and the wet test specimen 616 is gently removed from the sample chamber using tweezers. The wet caliper of the test specimen is then measured.

[0110] The wet caliper of the test sample 616 is measured immediately after the measurement procedure is completed using a manual micrometer equipped with a footplate capable of exerting a steady pressure of 2.07 kPa + 0.07 kPa. The manual micrometer is a dead-weight instrument with a reading accurate to 0.01 mm. A suitable instrument is the Mitutoyo Series 543 ID-C Digimatic, available from Avantor / VWR International (Radnor, Pennsylvania), or equivalent. The footplate has a flat, circular, movable surface with a diameter of 19 mm. The test sample is supported by a horizontal, flat reference platform that is larger than and parallel to the surface of the footplate. The micrometer is zeroed against the horizontal, flat reference platform. The wet test sample 616 is transferred to the micrometer's reference platform so that the sample 616 is centered, horizontal, and flat beneath the footplate. The footplate is manually lowered at a rate of 3 + 1 mm / sec until the full pressure (2.07 kPa) is applied to the test sample. After 5 seconds, record the caliper of the wet test sample as the sample caliper to the nearest 0.01 mm. The test sample is then discarded.

[0111] If any test fluid remains in the fluid container 601 and the sample chamber, the test fluid is removed.

[0112] This procedure is repeated for a total of three replicate test samples.

[0113] A separate "blank" run measurement is performed by following the procedure above, except that only the sample support 605 and sample weight 604 are present in the sample chamber (i.e., no test sample is present). Note that the initial test fluid height, Hi, is 150 mm above the top surface of the sample support 605, not the surface of the sample. This blank measurement allows the permeability of the sample support 605 to be taken into account when calculating the permeability of the test sample.

[0114] Transmittance calculation Total transmittance k 合計 is the permeability of the test sample plus sample support, calculated from the time and volume of flow through the entire fluid height reduction from 150 mm of test fluid to 130 mm of test fluid. The total permeability for each replicate test sample was calculated using the formula below and was calculated to be 0.01E -10 m 2 Record in units.

[0115]

number

[0116]

number

[0117] The transmittance k of the sample support 605 ssup is similarly calculated from the time and volume of flow throughout the fluid height decrease from 150 mm to 130 mm of test fluid in a "blank" run. The permeability of the sample support 605 alone is described by the following equation, and is less than 0.01E -10 m 2 It is recorded in units of

[0118]

number

[0119]

number

[0120] The transmittance k of each replicate sample 試料 is calculated using the following formula, and then 1.01324998E +12 Multiply by and record to the nearest 0.1 darcy.

[0121]

number

[0122] where k is the arithmetic mean of the test sample transmittance for all three replicate test samples. 試料 is calculated and reported as transmittance in units of 0.1 darcy.

[0123] Compression recovery rate and dry caliper measurement method The compression recovery measurement method measures the compression recovery behavior along the z-direction of the test specimen on a Constant Rate of Extension (CRE) Universal Mechanical Testing System (a suitable instrument is the MTS Alliance using TestSuite software, available from MTS Systems Corp., Eden Prairie, MN) using a load cell with a measured force within 1% to 99% of the cell's limits (preferably 100 N).

[0124] In the procedure, a sample of the material of interest is slowly compressed along the z-direction to a maximum pressure of 0.5 psi (3,446 Pa), then slowly released from compression. Its initial caliper at 0.0058 psi (39.79 Pa) of light contact compression is measured at the beginning of the loading portion of the cycle, and its final caliper at the same light contact compression is measured at the end of the unloading portion of the cycle. The final caliper divided by the initial caliper multiplied by 100% is the compression recovery of the material for purposes herein.

[0125] All tests are performed in a conditioned room at 23°C ± 3°C and 50% ± 2% relative humidity, and test samples are conditioned in this environment for at least 2 hours before testing.

[0126] The upper and lower fixtures of the test system are stainless steel circular parallel-plate compression platens. The platen mounted on the movable CRE fixture has a diameter of 40 mm, and the platen mounted on the stationary CRE fixture has a diameter greater than 40 mm. Both platens have adapters that fit into the mounts of the CRE tester, allowing the platens to be clamped with their opposing surfaces lying along parallel planes perpendicular to the movement of the CRE tester crossbeam.

[0127] To obtain a test sample for measurement, a single layer of the dried target material is placed flat on a horizontal work surface and a 40 mm diameter circular test sample is punched out from it. When selecting a location for the sample, avoid areas of the target material that have folds, wrinkles, or tears. If the target material is a layer component of an absorbent article (e.g., a feminine hygiene pad), such as a topsheet or absorbent layer component, obtain a representative sample of the target material that is not incorporated into the absorbent article. Alternatively, if only a fully manufactured absorbent article is available as the source of the target material, in that example, separate the target layer component from the article without stretching or damaging it. Once the target layer component is removed from the article, punch out the test sample as described above. Weigh the test sample and record the dry mass to the nearest 0.001 g. Prepare a total of five test samples. Precondition the test sample for two hours at 23°C ± 2°C and 50% ± 2% relative humidity before testing.

[0128] A universal test frame for compression testing is prepared to measure force and distance for one cycle of loading (compression) and unloading (recovery) as follows: The crosshead motion is programmed so that the upper platen moves downward from the starting position relative to the lower platen at a rate of 0.025 mm / s until an end load of 4.33 N is reached (applying an end pressure of 3,446 Pa (0.50 psi) between the platens), after which the crosshead motion is reversed and the upper platen rises at the same rate of 0.025 mm / s until the crosshead and platen return to the starting position. The platens are adjusted so that the initial distance between their contact surfaces is 25.0 mm (starting position), and then the crosshead and load cell are zeroed. The test specimen is placed on the lower platen with the surface facing the wearer facing upward and centered below the upper platen. The compression / release cycle is initiated, and force (N), time (seconds), and displacement (mm) data are continuously collected at a rate of 50 Hz.

[0129] Calculate the initial caliper of the test specimen to the nearest 0.001 mm by subtracting from 25.0 mm the crosshead displacement recorded during light contact compression with a force of 0.05 N (0.0058 psi pressure between the platens) during the load / compression portion of the cycle.

[0130] During the load / compression portion of the cycle, calculate the mean caliper of the test specimen to the nearest 0.001 mm by subtracting the crosshead displacement recorded at compression with a force of 0.8665 N (0.10 psi pressure between the platens) from 25.0 mm. For purposes herein, this calculated value is the dry caliper of the specimen.

[0131] Calculate the final caliper of the test specimen to the nearest 0.001 mm by subtracting from 25.0 mm the crosshead displacement recorded at light contact compression with a force of 0.05 N (0.0058 psi pressure between the platens) during the unload / recovery portion of the cycle.

[0132] The compression recovery of the sample is calculated as follows: Compression recovery rate = (final caliper / initial caliper) x 100%

[0133] The procedure is repeated for each of the five test samples, the average of each of the resulting values ​​is calculated, and the averages are reported as Dry Caliper (average of the Dry Caliper for the five samples) and Compression Recovery (average of the Compression Recovery for the five samples).

[0134] In light of the foregoing disclosure, the following examples are contemplated herein. 1. A feminine hygiene pad (10) comprising a liquid-permeable topsheet (20), a liquid-impermeable backsheet (40), and an absorbent system disposed between the topsheet and the backsheet, wherein the absorbent system: an absorbent foam layer (30) beneath the topsheet, the foam layer having a wearer-facing surface, an outward-facing surface, and a plurality of apertures (31, 32) providing z-directional passageways from the wearer-facing surface to the outward-facing surface; a porous spacer layer (50) beneath the foam layer and underlying most, preferably substantially all, and more preferably all, of the openings of the apertures in the outwardly facing surface of the foam layer.

[0135] 2. The feminine hygiene pad of Example 1, wherein the spacer layer (50) comprises a collection of fibers (polymer fibers) spun from one or more thermoplastic polymer resins.

[0136] 3. A feminine hygiene pad as described in Example 2, wherein the majority, preferably substantially all, and more preferably all, of the basis weight of the fibrous aggregate is composed of polymeric fibers.

[0137] 4. A feminine hygiene pad described in either Example 2 or 3, wherein the polymer resin comprises one or more polymers selected from the group consisting of PE, PP, and PET, and combinations thereof.

[0138] 5. A feminine hygiene pad according to any one of Examples 2 to 4, wherein the fiber is a bicomponent fiber.

[0139] 6. The feminine hygiene pad of Example 5, wherein the bicomponent fibers are curled or crimped.

[0140] 7. A feminine hygiene pad described in either Example 5 or 6, wherein the bicomponent fiber has a sheath-core configuration.

[0141] 8. The feminine hygiene pad of Example 7, wherein the core component comprises PET.

[0142] 9. A feminine hygiene pad described in either Example 7 or 8, wherein the sheath component comprises PE.

[0143] 10. The feminine hygiene pad of any of Examples 2-9, wherein the polymeric fibers have an average denier of at least 1, more preferably at least 2.

[0144] 11. The feminine hygiene pad of any one of Examples 1 to 10, wherein the spacer layer (50) is secured within the pad via a deposit of adhesive.

[0145] 12. The feminine hygiene pad of Example 11, wherein the adhesive is disposed primarily around the peripheral region (50p) of the spacer layer.

[0146] 13. The feminine hygiene pad of Example 12, wherein the adhesive is primarily disposed between the spacer layer and the absorbent layer.

[0147] 14. The feminine hygiene pad of example 11, wherein the adhesive is located primarily between the spacer layer and the backsheet.

[0148] 15. The spacer layer (50) is at least 1,000 mm 3 The feminine hygiene pad according to any one of Examples 1 to 14, having a void volume of

[0149] 16. The feminine hygiene pad of any one of Examples 1 to 15, wherein the spacer layer (50) has a permeability of at least 1,000 darcy, preferably at least 3,000 darcy, and more preferably at least 5,000 darcy.

[0150] 17. A feminine hygiene pad according to any one of Examples 1 to 16, wherein the spacer layer (50) has a dry caliper of 3.0 mm or less, more preferably 2.0 mm or less, even more preferably 1.5 mm or less, and also more preferably 1.0 mm or less.

[0151] 18. A feminine hygiene pad according to any one of Examples 1 to 17, wherein the spacer layer (50) exhibits a compression recovery rate of at least 75 percent.

[0152] 19. The apertures present in the ejection area are 3 mm 2 ~13mm 2 , more preferably 5 mm 2 ~10mm 2 The feminine hygiene pad according to any one of Examples 1 to 18, having an average xy plane open area on the surface of the absorbent layer facing the wearer.

[0153] 20. The apertures present in the discharge area are 1 cm on the wearer-facing surface of the absorbent layer. 2 3.0 to 9.0 apertures per cm, preferably 1 cm 2 4.0 to 8.0 apertures per cm, or even more preferably 1 cm 2 The feminine hygiene pad of any one of Examples 1 to 19, having a numerical density of 5.0 to 7.0 apertures per pad.

[0154] 21. The feminine hygiene pad of any one of Examples 1 to 20, wherein the foam layer (30) comprises a HIPE foam.

[0155] 22. The feminine hygiene pad of Example 21, wherein the foam layer (30) has two sublayers (30a, 30b) formed together, including a wearer-facing sublayer having a first average cell size and an outward-facing sublayer having a second average cell size, the second average cell size being smaller than the first average cell size.

[0156] 23. A feminine hygiene pad according to any one of Examples 1 to 22, wherein the material constituting the spacer layer (50) is hydrophilic or has been treated to make its surface hydrophilic.

[0157] All documents cited herein, including any cross-referenced or related patents or patent applications, and any patent applications or patents to which this application claims priority or benefit, are incorporated herein by reference in their entirety, unless expressly stated to the contrary. The citation of any document shall not be deemed to be prior art to any invention disclosed or claimed herein, or to teach, suggest, or disclose any such invention, either alone or in combination with any other reference or references. Furthermore, if any meaning or definition of a term in this document 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 document shall control.

[0158] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A feminine hygiene pad (10) comprising a liquid-permeable topsheet (20), a liquid-impermeable backsheet (40), and an absorbent system disposed between the topsheet and the backsheet, wherein the absorbent system: an absorbent foam layer (30) beneath the topsheet, the foam layer having a wearer-facing surface, an outward-facing surface, and a plurality of apertures (31, 32) providing z-direction passageways from the wearer-facing surface to the outward-facing surface; a porous spacer layer (50) beneath the foam layer and underlying most, preferably substantially all, and more preferably all, of the openings of the apertures on the outwardly facing surface of the foam layer.

2. 2. The feminine hygiene pad of claim 1, wherein the spacer layer (50) comprises a collection of fibers (polymer fibers) spun from one or more thermoplastic polymer resins, and the majority, preferably substantially all, and more preferably all, of the basis weight of the fiber collection is constituted by the polymer fibers.

3. 3. The feminine hygiene pad of claim 2, wherein the polymer resin comprises one or more polymers selected from the group consisting of PE, PP, and PET, and combinations thereof.

4. 4. The feminine hygiene pad of claim 2, wherein the fibers are bicomponent fibers.

5. 5. The feminine hygiene pad of claim 4, wherein the bicomponent fibers are curled or crimped.

6. The feminine hygiene pad of claim 4 or 5, wherein the bicomponent fibers have a sheath-core configuration.

7. The feminine hygiene pad of claim 6, wherein the core component comprises PET.

8. The feminine hygiene pad of claim 6 or 7, wherein the sheath comprises PE.

9. The feminine hygiene pad according to any one of claims 2 to 8, wherein the polymeric fibers have an average denier of at least 1, more preferably at least 2.

10. The feminine hygiene pad of any one of claims 1 to 9, wherein the spacer layer (50) is secured within the pad via a deposit of adhesive.

11. The feminine hygiene pad of claim 10, wherein the adhesive is disposed primarily around a peripheral region (50p) of the spacer layer and primarily between the spacer layer and the absorbent layer.

12. The spacer layer (50) is at least 1,000 mm ３ and a dry caliper of 3.0 mm or less, more preferably 2.0 mm or less, even more preferably 1.5 mm or less, and also more preferably 1.0 mm or less.

13. The feminine hygiene pad according to any one of claims 1 to 12, wherein the spacer layer (50) has a permeability of at least 1,000 darcy, preferably at least 3,000 darcy, more preferably at least 5,000 darcy.

14. The feminine hygiene pad of any one of claims 1 to 13, wherein the spacer layer (50) exhibits a compression recovery of at least 75 percent.

15. The feminine hygiene pad according to any one of claims 1 to 14, wherein the material of which the spacer layer (50) is made is hydrophilic or has been treated to make its surface hydrophilic.

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