Female panty liner with foam absorber and reservoir spacing layer

Abstract

A female panty liner having an absorbent system is disclosed, the absorbent system comprising: an absorbent foam layer having a wearer-facing surface and an outwardly-facing surface, having a plurality of apertures providing z-directional channels from the wearer-facing surface to the outwardly-facing surface; and a porous spacer layer under the foam layer and under the opening of the majority of the pores in the outwardly facing surface of the foam layer. The spacer layer acts to provide a structure under the absorbent foam layer that maintains a desired amount of unoccupied space open between the absorbent layer and the backsheet of the panty liner for the time required for the absorbent layer to effectively absorb fluid into which unabsorbed menstrual fluid may flow and temporarily reside.

Description

Background Art

[0001] Feminine sanitary pads comprising open-cell foam absorbent materials can be manufactured to have good absorbency, relatively thin / low thickness, and soft, pliable, resilient and soft feel - a combination of these features valued by feminine sanitary pad users. However, for some users, it may be desirable for the pad to provide a greater acquisition speed, and additionally or alternatively, to provide a greater ability to effectively absorb relatively rapidly discharged menstrual fluid than is currently associated with such pads. Especially for users who tend to experience relatively large menstrual volumes, during periods of rest or relative inactivity, a certain amount of menstrual fluid may be collected in the vaginal cavity and then suddenly discharged by constant changes in body movements. For such users, one or both of the above-mentioned enhancements can further reduce the risk that the fluid may overflow from the pad before the pad can absorb and contain the fluid, and stain underwear, outerwear, bedding, etc. There is room for further improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Figure 1 is a top plan view of an example of a non-limiting feminine hygiene pad.

[0003] Figure 2A and Figure 2B Yes Figure 1 A top plan view of a feminine hygiene pad shown in , showing two different, non-limiting examples of hole patterns with the top sheet layer removed.

[0004] Figure 3A It is along Figure 1 3-3 interception from the center line Figure 1 and Figure 2A Schematic lateral cross-section of a pad.

[0005] Figure 3B yes Figure 3A An expanded view of the pad shown in .

[0006] Figure 4 In an alternative non-limiting example, Figure 3A An expanded view of the pad is shown.

[0007] Figure 5 yes Figure 1 An underside plan view of a feminine hygiene pad showing the backing layer removed and depicting the boundary between the central area and the peripheral area of ​​the spacing layer.

[0008] FIG. 6A to FIG. 6C is a schematic expanded view of a non-limiting example of adhesive deposits in the drain area.

[0009] Fig. 7Ais a schematic cross-section of a measurement apparatus configuration for use in the permeability measurement methods described herein, taken along a vertical plane bisecting the depicted fluid container 601 .

[0010] Figure 7B Yes Fig. 6A A view of a measuring device is shown, showing the added elements when preparing to start a measuring procedure.

[0011] Figure 7C Yes Figure 6B The view of the measuring device is shown after starting a measuring procedure.

[0012] Fig. 8A is a perspective view of a sample weight used in the permeability measurement methods described herein.

[0013] Figure 8B yes Fig. 7A Top view of the sample weight depicted in .

[0014] Figure 8C It is along Figure 7B The line BB shown in Fig. 7A Vertical cross-section of the sample weight depicted in .

[0015] Fig. 9 is a top view of a sample support used in the permeability measurement methods described herein. DETAILED DESCRIPTION

[0016] definition

[0017] For the purposes of this document, the following terms have the following definitions:

[0018] A "hole" is an opening of any xy-plane shaped profile that is intentionally formed, punched or cut completely through a layer in the z-direction to provide z-direction passage through the layer.

[0019] "Lateral" - with respect to absorbent articles such as feminine hygiene pads or parts thereof, refers to the direction parallel to a horizontal line tangent to the front surface of the upper portion of the wearer's legs adjacent to the torso when the pad is worn normally and the wearer assumes a flat, square, normal standing position. The "width" dimension of any component or feature of an article such as a feminine hygiene pad is measured in the lateral direction. When the article or a component thereof is laid flat on a horizontal surface, the "lateral" direction corresponds to the lateral direction relative to the structure when it is worn, as defined above. With respect to articles such as feminine hygiene pads that are opened and laid flat on a horizontal plane surface, "lateral" refers to the direction perpendicular to the longitudinal direction and parallel to the horizontal plane surface. With respect to absorbent articles, the "x-direction" is also a lateral direction.

[0020] The "lateral axis" of an absorbent article such as a feminine hygiene pad or component thereof is a lateral line that lies in the xy plane and bisects the length of the pad or component thereof when the pad or component thereof is laid flat on a horizontal surface. The lateral axis is perpendicular to the longitudinal axis.

[0021] "Longitudinal" - with respect to an absorbent article such as a feminine hygiene pad or a component thereof, refers to the direction perpendicular to the lateral direction. The "length" dimension of any component or feature of the article is measured along the longitudinal direction from its forward extent to its rearward extent. When an article such as a feminine hygiene pad or a component thereof is laid flat on a horizontal surface, the "longitudinal" direction is perpendicular to the lateral direction relative to the pad when it is worn, as defined above. With respect to an absorbent article, the "y-direction" is also the longitudinal direction.

[0022] The "longitudinal axis" of a feminine hygiene pad or component thereof is a longitudinal line that lies in the xy plane and bisects the width of the pad or component thereof when the pad is laid flat on a horizontal surface. The longitudinal axis is perpendicular to the lateral axis.

[0023] With respect to absorbent articles such as feminine hygiene pads, or components thereof, "xy plane" refers to any horizontal surface occupied by the horizontal surface, or any layer of the article or component, when lying flat on that surface.

[0024] With respect to absorbent articles (such as feminine hygiene pads or components thereof), the "z-direction" is the direction perpendicular / normal to the xy plane when laid flat on a horizontal surface.

[0025] The terms "top", "bottom", "upper", "lower", "above", "below", "below", "upper adjacent", "lower adjacent" and similar terms characterizing relative vertical positioning, when used herein to refer to layers, components or other features of an absorbent article (such as a feminine hygiene pad), are relative to the z-direction and are to be interpreted relative to the orientation of the article as it would appear when laid flat on a horizontal surface, with the wearer-facing surface of the pad oriented upward and the outward-facing surface oriented downward.

[0026] With respect to absorbent articles such as feminine hygiene pads, or components or structures thereof, "wearer-facing" is a relative positional term that refers to a feature of a component or structure that is closer to the wearer when in use than another feature of the component or structure. For example, a topsheet has a wearer-facing surface that is closer to the wearer than an opposite, outwardly facing surface of the topsheet.

[0027] With respect to absorbent articles such as feminine hygiene pads, or components or structures thereof, "outwardly facing" is a relative positional term referring to a feature of a component or structure that is further away from the wearer when in use than another feature of the component or structure. For example, a topsheet has an outwardly facing surface that is further away from the wearer than an opposite, wearer-facing surface of the topsheet.

[0028] When used to characterize the amount of weight, volume, surface area, etc. of an absorbent article or part thereof that is composed of a composition, material, feature, etc., "mainly" and its forms mean that the majority of such weight, volume, surface area, etc. of the absorbent article or part thereof is composed of the composition, material, feature, etc. DETAILED DESCRIPTION

[0030] See also Figure 1 , Figure 2 and Figure 3A , the feminine hygiene pad 10 may include a liquid-permeable top sheet 20, a liquid-impermeable back sheet 40, and an absorbent layer 30 disposed between the top sheet and the back sheet. The absorbent layer has a peripheral edge 35. In the area outside the peripheral edge 35, the top sheet and the back sheet may be bonded together in a laminated manner by any suitable mechanism including, but not limited to, adhesive bonding, thermal bonding, pressure bonding, etc., thereby maintaining and fixing the absorbent layer 30 in a suitable position between the top sheet 20 and the back sheet 40. The pad 10 may include relative wings 25 that extend laterally outside the peripheral edge 35 and extend in a width dimension that is relatively larger than the main portion of the pad. The wings 25 may be formed by a back sheet 25b (shown in FIG. 2 ) and / or a top sheet 25t (shown in FIG. 3 ). Figure 5 The panty liner 10 may be formed by embossed lateral extensions of the panty liner (not shown). The outer surface of the backsheet forming the underside of the main portion and wing portions may have a deposit of adhesive (not shown) thereon. Such an adhesive deposit may be provided to enable the user to adhere the pad to the inside of her panties in the crotch area of ​​the panties and to wrap the wing portions through and around the inside edges of the leg openings of the panties and adhere them to the outside / underside of the panties in the crotch area, thereby providing additional retention support and helping to protect the leg edges of the panties from soiling. When the panty liner 10 is packaged, the adhesive deposit may be covered by one or more pieces of release film or paper (not shown) which cover / shield the adhesive deposit from contact with other surfaces until the user is ready to remove the release film or paper and place the panty liner for use.

[0031] Top sheet

[0032] The topsheet 20 is positioned adjacent to the wearer-facing surface of the absorbent layer 30 and may be joined thereto and to the backsheet 40 by any suitable attachment or bonding method. The topsheet 20 and the backsheet 40 may be directly joined to each other in the peripheral region beyond the peripheral edge 35 of the absorbent layer 30 and may be indirectly joined by directly joining them to the wearer-facing surface and the outward-facing surface, respectively, of the absorbent layer or to additional optional layers included in the pad.

[0033] The top sheet 20 is formed by a single or laminated material that is preferably compliant, soft-feeling and non-irritating to the wearer's skin. Suitable top sheet materials will include liquid-permeable materials that are comfortable and allow discharged menstrual fluid to penetrate quickly when in contact with the wearer's skin. Suitable top sheets can be made of various materials, such as suitable perforated liquid-permeable films, liquid-permeable nonwoven web materials, or combinations or laminates thereof.

[0034] In some non-limiting examples, the top sheet 20 may be formed of a polymeric film material having holes therethrough, the holes being provided to enable fluid to move from the wearer-facing surface through the top sheet to the absorbent material below. Such liquid-permeable apertured films are known in the art. They provide a resilient three-dimensional fabric-like structure. Such films have been disclosed in detail, for example, in US 3,929,135; US 4,151,240; US 4,319,868; US 4,324,426; US 4,343,314; US 4,591,523; US 4,609,518; US 4,629,643; US 4,695,422 and WO 96 / 00548.

[0035] In other non-limiting examples, the top sheet 20 may be formed of a liquid permeable nonwoven web material. Examples of nonwoven web materials suitable for use as top sheets include fibrous materials made of natural fibers, modified natural fibers, synthetic fibers, or combinations thereof. Some suitable examples are described in U.S. Patents 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.

[0036] In some examples, the top sheet may include a tufted structure, such as described in US 8,728,049, US 7,553,532, US 7,172,801, US 8,440,286, US 7,648,752, and US 7,410,683. The top sheet may have a pattern of discrete hair-like fibrils as described in US 7,655,176 or US 7,402,723. Additional examples of suitable top sheet materials include those described in US 8,614,365; US 8,704,036; US 6,025,535, and US 2015 / 041640. Another suitable top sheet may be formed from a three-dimensional substrate, such as described in detail in US 2017 / 0258647. The topsheet may have one or more layers as described in US 2016 / 0167334, US 2016 / 0166443 and US 2017 / 0258651.

[0037] As contemplated herein, the component nonwoven web material from which the top sheet 20 can be cut can be a nonwoven web material comprising or consisting essentially (by weight) of fibers spun from a polymer resin, such as a polyolefin, including polypropylene, polyethylene, and variants, blends, and bicomponent or multicomponent arrangements thereof.

[0038] Nonwoven webs can be formed via any suitable method by which indefinite lengths of spun fibers can be distributed in a controlled manner and accumulated on a moving forming belt to form flakes with a desired fiber distribution, reaching a desired basis weight. Suitable methods may include spunbond and meltblown processes. After accumulation, flakes may be processed by any suitable method to consolidate and bond the fibers into a cohesive web, including calendering, calendering thermal bonding, calendering compression bonding, through-air bonding, etc. The consolidated web may be subjected to additional processes such as water reinforcement or spunlace to increase the z-direction entanglement of the fibers and to increase bulk.

[0039] In some examples, the nonwoven web material may be formed in a coforming process in which hydrophilic fibers of finite length (such as plant-based, e.g., cotton fibers, rayon, etc.) are physically blended or mixed with a longer but indefinite length spun fiber stream, spun from a polymer resin, and placed on a forming belt to form a web, as described in, for example, US 8,017,534; US 4,100,324; US 2003 / 0200991; US ​​5,508,102; US2003 / 0211802; EP 0 333228; WO 2009 / 10938; US2017 / 0000695; US2017 / 0002486; US 9,944,047; 2017 / 0022643 and US2018 / 0002848.

[0040] If the materials and / or processes involved are not enhanced, generally speaking, the monocomponent fibers spun from polymer resins tend to have relatively simple surface geometries (generally circular or approximately elliptical cross-sections) and have substantially non-crimped or non-curled configurations along their lengths. Therefore, 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 bulk and a relatively flat appearance compared to a web of comparable basis weight formed by fibers of more complex shaping (e.g., crimped or curled). Nonwoven webs of lower bulk may be perceived by some consumers as having a relatively unpleasant feel and appearance, i.e., they may be perceived as being relatively not as soft or luxurious as nonwoven webs of higher bulk.

[0041] In order to increase the fluffiness of the fiber web without increasing the basis weight (and material usage), and in order to increase the opacity of the fiber web, a multi-component, for example, bi-component fiber configuration can be used to spin fibers for preparing the fiber web. Resin processing equipment and spinneret boxes can be constructed, and polymer resins can be selected to spin bi-component fibers, which curl or shrink when they leave the spinneret as a molten polymer stream, and then cool and solidify into fibers. Known processes and polymer resins can be used to select to prepare crimped spinning bi-component fibers, wherein the fibers have a 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 melting temperature and / or cooling shrinkage different from another polymer component. When cooling, the different characteristics of the polymer components and the non-coaxial cross-sectional arrangement of the component parts of the molten fiber stream give the fiber a curling when it cools, shrinks and solidifies at different rates. The corresponding polymer resin components can be different polymers, different forms or variants of the same polymer, or different blends thereof. More detailed disclosure of spun crimped or crimped bicomponent fibers and their formation into nonwoven webs can be found, for example, in US 8,501,646; US EP 1 988 793; and US 2007 / 0275622. In some examples, the bicomponent fibers may have respective majority polypropylene-based resin components that are formulated to impart different melting temperatures to the respective components. In some examples, the bicomponent fibers may have respective components, one of which is a majority polypropylene-based component and the other is a majority polyethylene-based component. In some more specific examples, the bicomponent fibers may be spun in an eccentric core-sheath component configuration, wherein the majority polypropylene-based component is the core component and the majority polyethylene-based component is the sheath component; wherein the polypropylene-based component may be desirable for its greater tensile strength, and the polyethylene-based component may be desirable for its smoother, more lubricated surface feel, which helps impart a silky feel to the fibers and nonwoven web materials. It should be understood that other combinations of polyolefins and / or other spinnable thermoplastic resins may be selected for their different cooling shrinkages and other different qualities that affect the qualities (including crimp or curl) and properties of the spun fibers in different ways.

[0042] However, the bicomponent fiber component can be used to impart a perceptible pillow-like elastic loft to the topsheet web material while avoiding undesirable pilling by including, at least on the wearer-facing side of the web, a spun monocomponent fiber layer, which can be a relatively thin layer, covering the bicomponent fiber layer. On a web forming line having a moving forming belt, one or more boxes configured to spin bicomponent fibers can be disposed upstream of a box configured to spin monocomponent fibers. In this configuration, the downstream monocomponent fiber spinning manifold is configured to deposit a spun monocomponent fiber layer on previously deposited bicomponent fibers on the moving belt. Alternatively, the monocomponent fiber spinning manifold can be located upstream of the bicomponent fiber spinning manifold. In both cases, it is contemplated that the monocomponent fiber layer will be used as the wearer-facing layer of the topsheet in the final product of a feminine hygiene pad. After forming a spun fiber batt having layers of bicomponent fibers and monocomponent fibers, the batt may be calender bonded in the nip between a pair of calender bonding rolls (one or both of which carry a pattern of bonding protrusions) to thereby form a pattern of fusion bonds in the fiber web via heat and / or compression, thereby reflecting the pattern of bonding protrusions on the rolls. In order to maximize the likelihood of effective fusion bonding at each bond site, it may be desirable that the polymer resin component of at least one component portion of the bicomponent fibers and the polymer resin component of the spun monocomponent fibers have similar chemical properties.

[0043] In some cases, it may be desirable that the roll with the bonding protrusions is the roll facing the monocomponent fiber layer in the nip, which can help impart a quilted appearance to the monocomponent / wearer-facing layer - to enhance the perception of pillow-like loft in the topsheet. In other cases, it may be desirable that the roll with the bonding protrusions is the roll facing the bicomponent fiber layer in the nip - this can help improve the cohesion of the fiber web.

[0044] In order to retain the pillow-like, bulky and elastic appearance of the fiber web material and avoid imparting an undesirable amount of stiffness to the fiber web produced by bonding, it may be desirable that the bonding area ((total bonding area / total fiber web area) x 100%) is 8% to 20%, or more preferably 10% to 16%. The percentage of bonding area for bonding nonwoven fiber web materials is often understood to be reflected as the sum of the areas of the bonding surfaces (sometimes referred to as "land") of the bonding protrusions on the calender bonding roll used to the total circumferential surface area of ​​the active portion of the calender bonding roll with the bonding protrusion pattern. The bonding area is often specified in the drawings, or can be calculated based on the size and numerical density / roller surface area of ​​the bonding protrusions reflected in such drawings, which are used to depict the bonding protrusion pattern and show the specifications for manufacturing the bonding roll.

[0045] In order to ensure that the fluid contacting the top (wearer-facing) surface of the hydrophilic topsheet will move appropriately and quickly in the z-direction via capillary action to the bottom (outward-facing) surface of the topsheet, where the fluid can be drawn into the absorbent layer, it may be important to ensure that the nonwoven web material forming the topsheet has an appropriate weight / volume density, reflecting the appropriate presence of interstitial channels in and between the constituent fibers, through which the fluid can move within the nonwoven material. A nonwoven with fibers that are too densely consolidated will have an insufficient number and volume of interstitial channels, and the nonwoven will block rather than promote rapid z-direction fluid movement. On the other hand, a nonwoven with fibers that are not sufficiently consolidated to provide sufficient fiber-to-fiber contact and / or sufficiently small interstitial channels can provide insufficient potential for wicking in the z-direction via capillary action. In order to balance the web bulk, opacity and mechanical strength with the thickness and fiber count / web density constraints on the one hand, and to allow the discharged fluid to move rapidly in the z-direction, it may be desirable to manufacture the combined bicomponent fiber / monocomponent fiber web to a basis weight of 17 gsm (grams / square meter) to 33 gsm, or more preferably 21 gsm to 29 gsm. In order to ensure a suitable z-direction wicking speed, it may be preferred that the web be manufactured to have a thickness of 0.008 mm to 0.014 mm per unit basis weight in gsm. For example, for a web with a basis weight of 25 gsm, it may be preferred that the web be manufactured to have a thickness of 0.20 mm (0.008 mm x 25) to 0.35 mm (0.014 mm x 25). For the purposes of this article, the thickness of the nonwoven web is measured using the following dry thickness measurement method. It will be appreciated that thickness can be adjusted by the degree of compression applied to the web during calendering, the density and bond area of ​​the bond pattern used, the amount of crimp or curl imparted to the bicomponent fibers, etc. The monocomponent fiber layer (wearer-facing layer) may constitute from 10% to 70%, more preferably from 20% to 50%, and even more preferably from 25% to 45% of the total basis weight of the web.

[0046] As described, forming a nonwoven web material having spun fibers including crimped bicomponent fibers can help increase the opacity of the web compared to a spunbond web formed only by monocomponent fibers. This is believed to be the result of increased light scattering and diffusion caused by greater fiber shape complexity and greater web bulkiness. It has been recognized that greater opacity is beneficial to the purposes contemplated herein because it increases the hiding ability of the top sheet formed by the web material. In addition to incorporating bicomponent fibers, manufacturers can also enhance the opacity of the web material by adding a whitening or shading additive together with the resin spun into monocomponent and / or bicomponent fibers. In some specific examples, for any one, two or all of a single bicomponent fiber component and a monocomponent fiber component, manufacturing can include a titanium dioxide sunscreen / brightener in an amount of up to 1%, 2%, 3%, 4%, or even 5% by weight of the resin. In order to balance the hiding ability of the fiber web material with the basis weight and thickness limitations as described herein, it may be desirable to adjust the basis weight and component resin formulations (including the addition of opacifying additives to the extent deemed useful) to obtain an opacity level for the nonwoven fiber web material of 30% to 42%, as measured by the opacity measurement method described below.

[0047] Many commercially useful thermoplastic resins that can be expected to be processed and spun into bicomponent fibers are generally hydrophobic. Such resins include polyolefins, such as polypropylene and polyethylene. The nonwoven web material formed by such fibers will also be hydrophobic, and therefore will not be easy to accept or wick aqueous fluids such as menstrual fluid. Therefore, when using such resins, additional measures must be included to make the fibers and / or nonwoven webs hydrophilic. In some examples, a suitable surfactant can be applied to the nonwoven web after the nonwoven web is formed. In a more specific example, the suitable surfactant finishing agent used can be SILASTOL PHP 26, which is a product of Schill+Seilacher GmbH ( The finish may be applied to the web using any suitable method, for example, via a kiss-roll coater. The finish may be applied in an amount suitable to impart a desired level of hydrophilicity to the nonwoven web and thereby help impart a desired level of capillary absorption / desorption pressure thereto. In a particular example, a finish coating of SILASTOL PHP 26 may be applied in an amount sufficient to constitute, after drying, from 0.30% to 0.60%, more preferably from 0.40% to 0.50%, of the surfactant weight based on the basis weight of the nonwoven web material.

[0048] The absorbency and wicking properties may also vary depending on and be manipulated by the manner in which the web is further processed. Factors such as the level of consolidation (i.e., compaction) of the fiber clusters in the end structures and the orientation of the individual fibers within the end structures may affect the absorbency and wicking properties.

[0049] Therefore, for the purpose contemplated herein, in combination with being given suitable basis weight, density and / or thickness as described above, it may be desirable to form a nonwoven web material spun from thermoplastic polymer resin and used to prepare a top sheet in part or substantially as a whole via a nonwoven web manufacturing process, wherein most of the fibers are given a directional orientation including some z-direction orientations, rather than the orientation of the machine direction or xy plane bias formed mainly along the web structure. After any suitable process (e.g., via a spunbond process) in which the fibers are distributed and laid on the batt on the horizontal forming belt, an additional process step of forcing some fibers or their parts to be reoriented in the z direction may be adopted. Suitable process steps may include needle punching and hydroentanglement or water reinforcement. Due to its effectiveness in reorienting fiber length while fiber breakage is less and forming less broken fiber lint and surface fluff (free fiber ends extending from the surface of the web), it may be desirable to hydroentanglement or water reinforcement, wherein when the batt is conveyed through an array of fine high-speed water jets, the high-speed water jets may be directed to the batt. A vacuum dewatering system (where air is drawn in the z-direction through the web into a pattern of orifices or holes on a vacuum drum or belt that conveys the flakes, thereby pulling the sprayed water along with it) may be desirable because it tends to form, add, open and / or remove small z-direction channels roughly in the pattern of orifices or holes in the fiber matrix of the web. Without intending to be bound by theory, it is believed that the fiber portions oriented in the z-direction and the z-direction channels enhance the ability and tendency of the web to wick aqueous fluids in the z-direction. In a top sheet, this would mean that the material can more easily wick aqueous fluids from the wearer-facing surface of the top sheet to the outward-facing surface of the top sheet, that is, wick downward to the absorbent layer below, thereby wicking fluids less along the xy plane direction (causing stains from the discharged fluid to spread laterally and / or longitudinally).

[0050] Absorption layer

[0051] In some examples, the absorbent layer 30 may be formed of or include an absorbent open-cell foam material layer. In some examples, the foam material may include at least a first layer 30a and a second layer 30b of an absorbent open-cell foam material. Figure 4 ), these sublayers are directly associated face to face and in contact with each other. In such examples, the sublayer 30a facing the wearer can be a relatively large open-cell foam material, and the outwardly facing sublayer 30b can be a relatively small open-cell foam material, for purposes explained in more detail below.

[0052] The open cell foam may be a foam produced via polymerization of a continuous oil phase of a water-in-oil high internal phase emulsion ("HIPE").

[0053] The water-in-oil HIPE has two phases. One phase is a continuous oil phase containing monomers to be polymerized and an emulsifier to help stabilize the HIPE. The oil phase may also include one or more photoinitiators. The monomer component may be included in an amount of about 80% to about 99% by weight of the oil phase and about 85% to about 95% in some examples. An emulsifier component that is soluble in the oil phase and suitable for forming a stable water-in-oil emulsion may be included in the oil phase in an amount of about 1% to about 20% by weight of the oil phase. The emulsion may be formed at an emulsification temperature of about 20°C to about 130°C and about 50°C to about 100°C in some examples.

[0054] Generally, the monomers may be included in an amount of about 20% to about 97% by weight of the oil phase and may include at least one substantially water-insoluble monofunctional alkyl acrylate or alkyl methacrylate. For example, monomers of this type may include C4-C18 alkyl acrylates and C2-C18 alkyl 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.

[0055] The oil phase may also contain from about 2% to about 40% by weight of the oil phase and in some examples from about 10% to about 30% of a substantially water-insoluble multifunctional cross-linked alkyl acrylate or alkyl methacrylate. This cross-linked co-monomer or cross-linking agent is added to impart strength and elasticity to the resulting HIPE foam. Examples of this type of cross-linked monomer include monomers containing two or more activated acrylate, methacrylate groups, or combinations thereof. Non-limiting examples of this group 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-dimethylpropylene glycol diacrylate), hexanediol acrylate methacrylate, glucose pentaacrylate, sorbitan pentaacrylate, and the like. Other examples of crosslinking agents include mixtures of acrylate and methacrylate moieties, such as ethylene glycol acrylate-methacrylate and neopentyl glycol acrylate-methacrylate. The ratio of methacrylate:acrylate groups in the mixed crosslinking agent can be varied from 50:50 to any other ratio as desired.

[0056] Any third substantially water-insoluble comonomer may be added to the oil phase from about 0% to about 15% by weight, in some examples about 2% to about 8% by weight, based on the weight of the oil phase, to modify the properties of the HIPE foam. In some cases, it may be desirable to "toughen" monomers to impart 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") to provide a more uniform and better formed HIPE foam, resulting in better toughness, tensile strength, abrasion resistance, etc. Monomers may also be added to impart flame retardancy, as disclosed, for example, in US 6,160,028. Monomers may be added to impart color (e.g., vinylferrocene); to impart fluorescent properties; to impart radiation resistance; to impart radiopacity (e.g., lead tetraacrylate); to disperse charge; to reflect incident infrared light; to absorb radio waves; to make the surface of the HIPE foam ribs or cell walls wettable; or to achieve any other desired properties in the HIPE foam. In some cases, these additional monomers may slow down the overall process of converting the HIPE into a HIPE foam, a tradeoff that is necessary if the desired properties are to be imparted. Thus, such monomers may also be used to slow down the polymerization rate of the HIPE. Examples of this type of monomer include styrene and vinyl chloride.

[0057] The oil phase may also contain an emulsifier to stabilize the HIPE. Emulsifiers used in HIPE may include: (a) sorbitan monoesters of branched C16-C24 fatty acids; linear unsaturated C16-C22 fatty acids; and linear saturated C12-C14 fatty acids, such as sorbitan monooleate, sorbitan monomyristate and sorbitan monoesters, sorbitan monolaurate, diglycerol monooleate (DGMO), polyglycerol monoisostearate (PGMIS) and polyglycerol monomyristate (PGMM); (b) polyglycerol monoesters of branched C16-C24 fatty acids, linear unsaturated C16-C22 fatty acids or linear saturated C12-C14 fatty acids, such as diglycerol monooleate (e.g. diglycerol monomyristate of C18:1 fatty acids), diglycerol monoisostearate and diglycerol monoesters; (c) diglycerol monoaliphatic ethers of branched C16-C24 alcohols, linear unsaturated C16-C22 alcohols and linear saturated C12-C14 alcohols, and mixtures of these emulsifiers. See US 5,287,207 and US 5,500,451. Another emulsifier that can be used is polyglycerol succinate (PGS), which is formed by alkyl succinates, glycerol and triglycerol.

[0058] Such emulsifiers and combinations thereof may be added to the oil phase such that they constitute from about 1% to about 20%, in certain examples from about 2% to about 15%, and in certain other examples from about 3% to about 12% by weight of the oil phase. In certain examples, co-emulsifiers may also be used to provide additional control over cell size, cell size distribution, and emulsion stability, especially at higher temperatures, for example, greater than about 65°C. Examples of co-emulsifiers include phosphatidylcholine and compositions containing phosphatidylcholine, aliphatic betaines, long-chain C12-C22 dialiphatic quaternary ammonium salts, short-chain C1-C4 dialiphatic quaternary ammonium salts, long-chain C12-C22 dialkanoyl (alkenoyl) -2-hydroxyethyl, short-chain C1-C4 dialiphatic quaternary ammonium salts, long-chain C12-C22 dialiphatic imidazoline quaternary ammonium salts, short-chain C1-C4 dialiphatic imidazoline quaternary ammonium salts, long-chain C12-C22 monoaliphatic benzyl quaternary ammonium salts, long-chain C12-C22 dialkanoyl (alkenoyl) -2-aminoethyl, short-chain C1-C4 monoaliphatic benzyl quaternary ammonium salts, short-chain C1-C4 monohydroxyaliphatic quaternary ammonium salts. In some examples, ditallow dimethyl ammonium methyl sulfate (DTDMAMS) can be used as a co-emulsifier.

[0059] Any photoinitiator included may be included at about 0.05% to about 10% and in some examples about 0.2% to about 10% by weight of the oil phase. Lower amounts of photoinitiator enable light to better penetrate the HIPE foam, which can allow polymerization to penetrate deeper into the HIPE foam. However, if the polymerization is carried out in an oxygen-containing environment, it may be desirable to have enough photoinitiator to initiate polymerization and overcome the inhibition of oxygen. Photoinitiators can respond quickly and efficiently to light sources, thereby generating free radicals, cations, and other substances that can initiate polymerization reactions. Photoinitiators selected for forming foams within the contemplation of the present disclosure can absorb UV light having a wavelength of about 200 nanometers (nm) to about 800 nm, and in some examples about 250 nm to about 450 nm. If the photoinitiator is in the oil phase, suitable types of oil-soluble photoinitiators include benzyl ketals, α-hydroxyalkyl phenones, α-aminoalkyl phenones, and acylphosphine oxides. Examples of photoinitiators include a combination of 2,4,6-[trimethylbenzoyldiphosphine] oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one (a 50:50 blend of the two is sold as DAROCUR 4265 by Ciba Speciality Chemicals, Ludwigshafen, Germany); benzyl dimethyl ketal (sold as IRGACURE 651 by Ciba Geigy); α-,α-dimethoxy-α-hydroxyacetophenone (sold as DAROCUR 1173 by Ciba Speciality Chemicals); 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propan-1-one (sold as IRGACURE 907 by Ciba Speciality Chemicals); 1-hydroxycyclohexyl-phenyl ketone (sold as IRGACURE 908 by Ciba Speciality Chemicals); Chemicals as IRGACURE 184); bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (sold as IRGACURE 819 by Ciba Speciality Chemicals); diethoxyacetophenone and 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-methylpropyl)ketone (sold as IRGACURE 2959 by Ciba Speciality Chemicals); and oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] (sold as ESACURE KIP EM by Lamberti spa, Gallarate, Italy).

[0060] 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, wherein in certain examples, the one or more components are at least partially water-soluble.

[0061] One component included in the aqueous phase may be a water-soluble electrolyte. The aqueous phase may contain about 0.2% to about 40%, in some examples about 2% to about 20%, of a water-soluble electrolyte by weight of the aqueous phase. The electrolyte minimizes the tendency of the monomers, comonomers, and crosslinking agents that are primarily oil-soluble to also dissolve in the aqueous phase. Examples of electrolytes include chlorides or sulfates of alkaline earth metals such as calcium or magnesium, and chlorides or sulfates of alkali metals such as sodium. Such electrolytes may include buffers for controlling the pH during polymerization, including inorganic counterions such as phosphates, borates, and carbonates, and mixtures thereof. Water-soluble monomers may also be used in the aqueous phase, examples of which are acrylic acid and vinyl acetate.

[0062] Another component that can be included in the aqueous phase is a water-soluble free radical initiator. Based on the total moles of polymerizable monomers present in the oil phase, the initiator can be present in an amount of up to about 20 mol %. In some examples, based on the total moles of polymerizable monomers in the oil phase, the initiator can be included in an amount of about 0.001 mol % to about 10 mol %. Suitable initiators include ammonium persulfate, sodium persulfate, potassium persulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine)dihydrochloride, azo initiators, redox pairs such as persulfate-bisulfate, persulfate-ascorbic acid, and other suitable redox initiators. In some examples, in order to reduce the possibility of premature polymerization that can block the emulsified system, an initiator can be added to the monomer phase near the end of the emulsification step or shortly after the end of the emulsification step.

[0063] When included in the aqueous phase, the photoinitiator may be at least partially water-soluble and may constitute between about 0.05% and about 10% and in some examples between about 0.2% and about 10% by weight of the aqueous phase. Lower amounts of photoinitiators enable light to better penetrate the HIPE foam, which can allow polymerization to penetrate deeper into the HIPE foam. However, if the polymerization is carried out in an oxygen-containing environment, there should be enough photoinitiator to initiate polymerization and overcome the inhibition of oxygen. Photoinitiators can respond quickly and efficiently to light sources, thereby generating free radicals, cations, and other substances that can initiate polymerization reactions. Photoinitiators selected for forming foams within the contemplation of the present disclosure can absorb UV light with a wavelength of about 200 nanometers (nm) to about 800nm, about 200nm to about 350nm in some examples, and about 350nm to about 450nm in some examples. If the photoinitiator is to be included in the aqueous phase, suitable types of water-soluble photoinitiators may include benzophenone, benzil, and thioxanthone. Examples of photoinitiators include 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride; dehydrated 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate; 2,2'-azobis(1-imino-1-pyrrol-2-ethylpropane) dihydrochloride; 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; 2,2'-azobis(2-methylpropionamidine) dihydrochloride; 2,2'-dicarboxymethoxydibenzylideneacetone, 4,4'-dicarboxymethoxydibenzylideneacetone, 4,4'-dicarboxymethoxydibenzylideneacetone, 4-dimethylamino-4'-carboxymethoxydibenzylideneacetone; and 4,4'-disulfonylmethoxydibenzylideneacetone. Other suitable photoinitiators that may be used are listed in US 4,824,765.

[0064] In addition to the aforementioned components, other components may also be included in the aqueous or oil phase of the HIPE. Examples include antioxidants such as hindered phenols, hindered amine light stabilizers; plasticizers such as dioctyl phthalate, dinonyl sebacate; flame retardants such as halogenated hydrocarbons, phosphates, borates, inorganic salts such as antimony trioxide or ammonium phosphate or magnesium hydroxide; dyes and pigments; fluorescent agents; filler particles such as starch, titanium dioxide, carbon black or calcium carbonate; fibers; chain transfer agents; odor absorbers such as activated carbon particles; dissolved polymers; dissolved oligomers; and the like.

[0065] HIPE foam is produced by the polymerization of monomers comprising a continuous oil phase of HIPE. In some examples, the HIPE foam layer may have one or more sublayers and may be a homogeneous or heterogeneous polymer open-cell foam. Homogeneity and heterogeneity relate to different layers within the same HIPE foam, which are similar in the case of homogeneous HIPE foam and different in the case of heterogeneous HIPE foam. Heterogeneous HIPE foam may include at least two different sublayers, which differ in their chemical composition, physical properties, or both; for example, the sublayers may differ in one or more aspects of foam density, polymer composition, specific surface area, or pore size (also referred to as cell size). For example, for HIPE foam, if the difference involves pore size, the average pore size in the corresponding sublayer may differ by at least about 20%, in some examples by at least about 35%, and in other examples by at least about 50%. For another example, if the difference in the sublayer of the HIPE foam layer involves density, the density of the layer may differ by at least about 20%, in some examples by at least about 35%, and in other examples by at least about 50%. For example, if one layer of the 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 about 0.016 g / cc, in certain examples at least about 0.027 g / cc or less than about 0.013 g / cc, and in other examples at least about 0.030 g / cc or less than about 0.010 g / cc. If the difference between the layers relates 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, such as a difference of at least about 20%, a difference of at least about 35%, and in other examples a difference of at least about 50%. For example, if one sublayer of the HIPE or HIPE foam is composed of about 10% styrene in its formulation, another sublayer of the HIPE or HIPE foam may be composed of at least about 12%, and in certain examples at least about 15%.

[0066] A HIPE foam layer configured to have different sublayers formed from different HIPEs can provide a range of desired performance characteristics for the HIPE foam layer. For example, when used in an absorbent article, a HIPE foam layer comprising a first foam sublayer and a second foam sublayer, wherein the first foam sublayer has a relatively larger pore size or cell size than the second sublayer, can absorb incoming fluid faster than the second sublayer. For example, when a HIPE foam layer is used to form an absorbent layer of a feminine sanitary pad, the first foam sublayer can be laminated on a second foam sublayer having a relatively smaller pore size than the first foam sublayer, the second foam sublayer applying greater capillary pressure and drawing the collected fluid from the first foam sublayer, thereby restoring the ability of the first foam sublayer to collect more fluid from above. The HIPE foam pore size can range from 1 μm to 200 μm, and in some examples can be less than 100 μm. The HIPE foam layer of the present disclosure having two major parallel surfaces can be about 0.5 mm to about 10 mm thick, and in some examples about 2 mm to about 10 mm. The desired thickness of the HIPE foam layer will depend on the materials used to form the HIPE foam layer, the speed at which the HIPE is deposited on the belt, and the intended use of the resulting HIPE foam layer.

[0067] The HIPE foam layers of the present disclosure are relatively open-celled. This means that individual cells or pores of the HIPE foam layer are in substantially unobstructed communication with adjacent cells. The cells in such substantially open-celled HIPE foam structures have openings or windows between the cells that are large enough to allow fluid to easily transfer from one cell to another within the HIPE foam structure. For the purposes of this disclosure, a HIPE foam is considered "open-celled" if at least about 80% of the cells having a pore size of at least 1 μm in the HIPE foam are in fluid communication with at least one adjacent cell.

[0068] In addition to being open-celled, in certain examples, the HIPE foam is also adapted to be sufficiently hydrophilic to allow the HIPE foam to absorb aqueous fluids. In some examples, the interior surface of the HIPE foam can be rendered hydrophilic by residual hydrophilizing surfactants or salts remaining in the HIPE foam after polymerization, by selected post-polymerization HIPE foam treatment procedures (as described below), or a combination of both.

[0069] In certain examples, for example, when used to form the absorbent layer of a feminine hygiene pad, the 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 the polymer. Generally speaking, a HIPE foam with a Tg above the use temperature can be strong, but will also be relatively rigid and potentially prone to fracture (fragile). In certain examples, regions of the HIPE foam of the present disclosure that exhibit relatively high Tg or excessive brittleness will be discontinuous. Since these discontinuous regions will generally also exhibit high strength, they can be prepared at a lower density without compromising the overall strength of the HIPE foam.

[0070] HIPE foams intended for applications requiring flexibility should contain at least one continuous region having a Tg as low as possible, as long as the overall HIPE foam has acceptable strength at the in-use temperature. In some examples, for foams used at approximately ambient temperature conditions, the Tg of this region will be below about 40°C; in some other examples, the Tg will be below about 30°C. For HIPE foams used in applications where the use temperature is above or below ambient temperature, the Tg of the continuous region may be no more than 10°C higher than the use temperature, in some examples the same as the use temperature, and in other examples about 10°C lower than the use temperature when flexibility is desired. Therefore, monomers are selected that provide a corresponding polymer with a lower Tg as much as possible.

[0071] HIPE foams useful for forming absorbent layers and / or sublayers within the contemplation of the present disclosure and methods for their manufacture also include, but are not necessarily limited to, those foams and methods described in the following patents: US 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, 6,406,648, 6,376,565, 6,372,953, 6,369,121, 6,365,642, 6,207,724, 6,204,298, 6,158,144, 6,107,538, 6,584,670, 6,612,619, 6,708,710, 6,711,734, 6,713,736,671, 6,714,737,673, 6,715,738, 6,716,739, 6,717,739, 6,718,739, 6,720,731, 6,733,739,6 6,107,356, US 6,083,211, US6,013,589, US 5,899,893, US 5,873,869, US 5,863,958, US 5,849,805, US 5,827,909, US5,827,253, US 5,817,704, US 5,817,081, US 5,795,921, US 5,741,581, US 5,652,194, US 5,650,222, US 5,632,737, US 5,563,179, US 5,550,167, US 5,500,451、U.S. 5,387,207, US5,352,711, US 5,397,316, US 5,331,015, US 5,292,777, US 5,268,224, US 5,260,345, US5,250,576, US 5,149,720, US 5,147,345 and US2005 / 0197414, US2005 / 0197415, US 2011 / 0160326, US2011 / 0159135, US2011 / 0159206, US2011 / 0160321 and US2011 / 0160689, which are incorporated herein by reference to the extent not inconsistent herewith.

[0072] Absorption layer hole

[0073] like Figure 1 , Figure 2 and Figure 3AAs reflected, the absorbent layer 30 formed of foam may include one or more patterns of holes 31, 32, including at least a first pattern disposed within an intended drainage area 60. As identified for purposes herein, the drainage area 60 is coincident with the lateral axis 200 of the pad (but not necessarily longitudinally centered); is substantially centered on the longitudinal axis 100 of the pad; and has an elliptical profile with a major longitudinal axis of 5 cm long and a minor lateral axis of 2.5 cm wide. The holes 31, 32 may be formed by perforating, cutting, or otherwise through the entire z-direction depth of the foam absorbent layer. When the foam absorbent layer is disposed in direct contact with a top sheet as described herein, without an intervening acquisition layer formed of another material, the holes 31, 32 may serve as a set of small reservoirs to receive, temporarily hold, and facilitate the rapid drainage of relatively small amounts of menstrual fluid until the foam has had sufficient time to distribute and absorb the fluid via capillary action. Alternatively or in addition, as described herein, the holes can be used as channels to direct the sudden discharge of received fluid through the absorbent layer downwardly to the underlying spacing layer, which provides additional reservoir volume and fluid distribution capabilities. In addition, such holes also help reduce the bending stiffness of the absorbent layer 30, which can help improve the comfort of the pad for the wearer. In order to provide a channel through which fluid will easily flow, a pattern of circular, oval or stadium-shaped holes of the absorbent layer 30 can be included, for example, in the area occupied by the discharge area 60, the pattern having an average diameter or other maximum dimension of 2.0 mm to 4.0 mm and a maximum dimension of 3 mm. 2 Up to 13mm 2 , and more preferably an average xy plane opening area on the wearer-facing surface of 2.5 mm to 3.5 mm, and 5 mm 2 Up to 10mm 2 In order to strike a good balance between providing a sufficient number of channels without removing too much absorbent material from the absorbent layer 30 (taking away absorbent capacity), it may be desirable for the holes in the drainage zone 60 to have an average xy plane open area of ​​the wearer-facing surface of the absorbent layer 30 per cm of surface area. 2 3.0 to 9.0 holes, more preferably per cm 2 4.0 to 8.0 holes, or even more preferably per cm 2 In selecting the appropriate average size, numerical density, and surface area occupied by the hole pattern, the manufacturer may wish to balance the volume of the desired reservoir or channel with the need to keep the absorbent material in a location close to the intended discharge location. Additional details on the configuration of such holes in conjunction with examples of suitable absorbent layers can be found in US 8,211,078.

[0074] like Figure 3BAs shown, the pattern of holes 30, 31 will make the pad and foam absorbent layer 30 more receptive to sudden discharges of fluid and allow it to quickly pass through the absorbent layer down to the spacing layer and reside in the spacing layer during the time required for the absorbent layer to intake and absorb the fluid.

[0075] Interface between topsheet and absorbent layer

[0076] In examples where the topsheet is formed of a hydrophilic and / or absorbent web material, the topsheet material may tend to retain fluid on its wearer-facing and outward-facing surfaces and in the void spaces between and along the fiber surfaces of the web material unless the underlying material has an absorptive capacity and the absorptive pressure is greater than the desorption pressure of the topsheet and sufficient direct contact is maintained between the topsheet and the underlying absorbent layer to enable fluid to move directly from the fiber surfaces within the topsheet structure to the material surfaces within the underlying absorbent layer structure so that the underlying absorbent layer can draw fluid from the topsheet. Prior to its complete saturation, the absorbent material will not release the absorbed fluid unless an adjacent material having a greater affinity for the fluid is in sufficient direct contact. Therefore, it is important to provide a structure sufficient to maintain sufficient contact without impeding the movement of the fluid. No intervening material layer or structure, or at least no intervening material layer or structure having an absorbency less than that of the absorbent layer, should be inserted between the material of the top sheet 20 and the material of the absorbent layer 30, at least within the discharge area 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, as opposed to the systems provided in many current feminine sanitary pads which include a distinct layer of fluid acquisition / distribution material between the top sheet and the absorbent material of the absorbent core.

[0077] In some examples, substantially direct contact between the topsheet 20 and the absorbent layer 30 may be achieved by deposits of adhesive between the topsheet and the absorbent layer, thereby bonding 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 adhesive is not present (unbonded areas) such that the adhesive holds the two layers in close proximity in the z-direction, while areas where adhesive is not present impede z-direction fluid movement between the layers.

[0078] See also Figure 1 , Figure 2 and FIG. 6A to FIG. 6CIn order to ensure that the topsheet and the absorbent layer maintain sufficient z-direction proximity at least in the area of ​​the topsheet expected to receive fluid discharge, it may be desirable to locate the discharge region 60 on the pad at a location that includes the intersection of the longitudinal axis 100 and the lateral axis 200. The discharge region 60 should be of sufficient size to reliably reside below the expected discharge location when the pad is in use, with reasonably little variation in the wearer's placement in the underwear; thus, it may be desirable for the discharge region to have a width of at least 15 cm. 2 , more preferably at least 30 cm 2 Even more preferably, it may be desirable that the area of ​​the drainage zone is at least half of the total surface area of ​​the absorbent layer facing the wearer. (Note: FIG. 6A to FIG. 6C They are not presented in this article as actual size or depicted to scale.)

[0079] To ensure that the topsheet 20 and the absorbent layer maintain sufficient z-direction proximity during use, it may be desirable that within any identifiable first point location 27 where the topsheet is bonded to the absorbent layer within the discharge area, there is a second point location where the topsheet is bonded to the absorbent layer within a 10 mm radius, more preferably within a 6 mm radius, within a 5 mm radius, within a 4 mm radius, and even more preferably within a 3 mm radius r of the first point location. Figure 3A 3C (showing three non-limiting examples), it can be seen that a variety of bonding patterns or arrangements (via adhesive deposits 26 or other bonding mechanisms) can be used to impart this feature. Within radius r of each point location 27, there are multiple additional point locations in the example described where bonding between the top sheet and the absorbent layer exists.

[0080] It should be understood that a continuous deposit of adhesive may be applied to bond the top sheet and the absorbent layer throughout the discharge region 60, but such a continuous deposit of adhesive may form a barrier that will impede the movement of fluid from the top sheet to the absorbent layer. Therefore, it is preferred that in examples where the bonding mechanism is a deposit of adhesive, the deposit is arranged in a discontinuous or intermittent pattern or arrangement so that it forms a bonded area interspersed with unbonded areas between the top sheet and the absorbent layer. In addition, when the absorbent layer is formed by an open-cell foam (such as the foam contemplated herein), it may be desirable that the selected adhesive does not achieve adhesion to the absorbent layer via chemical, dispersed or diffuse adhesion to the foam layer at the adhesive deposition location, but rather that this is achieved by flowing into the pores to a limited extent (at least partially assuming their shape) and solidifying at such locations to form mechanical interlocks with the pore structure, which enable the adhesive to hold the top sheet to the absorbent layer. Such adhesives may be preferred so as not to change the molecular structure or composition of the foam material, thereby 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 available from Bostik, Wauwatosa, Wisconsin (currently a subsidiary of Arkema, Columbia, France).

[0081] Unapertured topsheets for feminine hygiene pads formed of nonwoven web materials and containing hydrophilic fibers or consisting mainly of hydrophilic fibers are known and have been included in some feminine hygiene products to date. (In this article, an "unapertured" nonwoven topsheet is a topsheet in which a large portion of its surface area is not subjected to any process for forming an arrangement of holes or holes that are completely throughout the topsheet, and the holes or holes are kept in the xy plane direction before the topsheet is wetted. An average size (maximum size) greater than 0.5 mm.) Although some consumers prefer their comfortable feeling against the skin, other consumers do not prefer topsheets formed of hydrophilic nonwoven web materials because of their basic absorbency (i.e., capillary absorption and desorption pressure), which makes them resist the discharge caused by conventional included acquisition / distribution and absorbent layer structures. After menstrual fluid is discharged, a pad with such a topsheet covered on a conventional absorbent structure can make the user feel like a wet cloth against the skin for a long period of time, which can make many users feel disgusted.

[0082] However, an unapertured hydrophilic fibrous topsheet overlapped in direct, sufficient 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, in the absence of any intervening less absorbent layer and in combination with other structural features as described herein, will substantially drain fluid through the absorbent layer and regain a drier feel against the skin after draining. A properly composed and manufactured HIPE foam absorbent layer as described herein, for example, has a greater affinity for menstrual fluid than such a topsheet, thereby having the ability to draw and hold fluid away from the topsheet when the two are placed and maintained in sufficiently effective proximity contact with each other. When the absorbent layer has sufficient volume, it can perform this function for a reasonably suitable use time of the pad.

[0083] Spacer

[0084] See also Figure 1 Figure 2 Figure 3A and Figure 3B , it is contemplated herein to include a spacer layer 50. The primary purpose of the spacer layer is to provide a structure under the absorbent layer 30 that maintains a desired amount of unoccupied space (i.e., a reservoir) open between the absorbent layer 30 and the backsheet 40, during the time required for the absorbent layer 30 to effectively absorb fluid, into which unabsorbed menstrual fluid can flow and temporarily reside. It is desirable that the spacer layer 50 be disposed under the absorbent layer 30, rather than over it, to help prevent the unabsorbed fluid from rewetting the topsheet. It is also desirable that the absorbent layer 30 include apertures 31, 32 extending completely therethrough, i.e., from the wearer-facing surface to the outward-facing surface, as described above, to provide a path for unabsorbed fluid to quickly move downward to the spacer layer.

[0085] It is contemplated herein that the spacer layer 50 may be formed entirely of, or alternatively include, an open-cell foam having a different composition than the foam absorbent layer and an average cell size greater than the average cell size of the foam absorbent layer. In some examples, the spacer layer may be formed of or include an open-cell polyurethane foam layer.

[0086] It is also contemplated herein that the spacer layer 50 may be formed entirely from or alternatively include a nonwoven batt, web, or bundle of fibers (collectively referred to herein as a "fiber assembly") formed from filaments or fibers (collectively referred to as fibers).

[0087] Where included, it may be desirable that such fiber assemblies 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 generally not absorbent because they generally do not include complex surface geometries, pores, or internal spaces into which fluids may flow and remain.

[0088] It may be desirable that the thermoplastic resin 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 greater stiffness per unit diameter or cross-sectional dimension than fibers spun from other polymers, and for purposes herein, fibers spun from PET are relatively abundant and cost effective.

[0089] In some examples, it may be desirable that the major portion of the fiber is a bicomponent fiber, and in some examples, it may be desirable that the bicomponent fiber is a crimped or curled bicomponent fiber. The crimped or curled bicomponent fiber may be produced by a combination of polymer fiber components having different melting temperatures and / or shrinkage rates when cooled, arranged in a side-by-side or "pie slice" component cross-sectional configuration, or by an eccentric component cross-sectional, such as an eccentric core-skin configuration. Through its geometry, the crimped or curled fiber imparts bulk and volume to the resulting nonwoven material, and therefore, the inclusion of the fiber may increase the volume of the open inter-fiber / interstitial space per unit thickness within the material. Therefore, in some examples, the spacer layer 50 may be formed by or include a fiber assembly that is primarily formed by or primarily includes crimped 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, for example, a fiber having a PET core component and a PE skin component. This particular combination enables the fiber collection to be strengthened and / or hardened via fiber-to-fiber thermal bonding, achieved, for example, by heating in an oven or hot air flow treatment, to better maintain volume / loft. The lower melting temperature of PE, due to its higher melting temperature, enables the PE sheaths of adjacent fibers to be fused without melting the PET core. This type of fiber-to-fiber bonding can be achieved without compressing the fiber collection, which can reduce loft / volume, as occurs in heat / compression local point bonding or calendering bonding.

[0090] In order to balance stiffness and resiliency to maintain loft and volume with flexibility 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.

[0091] As described above, it may be desirable that a major portion, substantially all, or all of the fibers or filaments that may form the spacer layer 50 be spun from an inherently hydrophilic material, or alternatively, be treated to be hydrophilic. The purpose is to enable the spacer layer 50 to readily accept fluid moving downward through and out of the pores 31, 32, and to wick or transport the fluid through the structure of the spacer layer so that it is distributed along the underside of the absorbent layer 30 to maximize its surface area exposure to the fluid, and thereby effectively and efficiently use the absorbent layer. If the spacer layer is primarily composed of a material having a hydrophobic surface, it may not easily accept or transport fluid discharged from the pores at the underside of the absorbent layer.

[0092] Based on the volume of the desired fluid reservoir space, it is preferred that the spacer layer 50 has a width of at least 1,000 mm. 3 (For purposes herein, void volume is calculated by multiplying the wearer-facing surface area of ​​the spacing layer by its dry thickness, minus the mass of each polymer present in the spacing layer divided by its density.) Dry thickness is measured by the steps described in the Compression Recovery and Dry Thickness Measurement Methods described below. However, in order to avoid imparting a level of thickness to the overall assembled product that may be found inappropriate by the wearer, it may be desirable that the dry thickness of the spacing layer be no greater than 3.0 mm, more preferably no greater than 2.0 mm, even more preferably no greater than 1.5 mm, and still more preferably no greater than 1.0 mm.

[0093] With regard to void volume, and in order to ensure that the spacer layer 50 will easily accept the fluid outflow from the holes 30, 31, it may be desirable that the spacer layer be manufactured to have a permeability that is not less than a minimum value. Generally speaking, "permeability" reflects the amount of resistance of a material to the passage or flow of a pressurized / forced liquid through it. A relatively high permeability reflects a relatively low resistance to fluid flow, and a relatively low permeability reflects a relatively high resistance to fluid flow. Two materials having the same void volume per unit gross volume may have different permeabilities; the permeability level of a material is substantially partially affected by the amount of solid material surface area (the fluid must pass / across the solid material surface area to move through the material) and the frictional resistance of the fluid moving above the surface. Therefore, for example, a first nonwoven web material composed of more and 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 wherein the fiber size is larger and the number is less, because the second material will have a smaller fiber surface area.

[0094] Therefore, for the purpose of this article, it may be desired that the spacer layer 50 is manufactured so as to have at least 1,000 Darcy, preferably at least 3,000 Darcy, and more preferably at least 5,000 Darcy, or 1,000 Darcy to 6,000 Darcy or other upper limits of the permeability of the specific material used to constitute the spacer layer. All sub-ranges within this larger range are conceivable in this article. For the purposes contemplated herein, permeability is measured using the following permeability measurement method. In one example, the nonwoven web material considered suitable for constituting the spacer layer for the purpose of this article is a carded staple fiber nonwoven web material, with a basis weight of 15gsm, a thickness of about 0.8mm when a 0.1psi pressure is applied in the z direction, wherein the fiber has an average denier of 6, and is composed of a bicomponent fiber spun in a sheath-core configuration, wherein the sheath component is formed by PE, and the core component is formed by PET, with a weight ratio of about 50:50. It was found that this material has a permeability of about 5,083 Darcy.

[0095] In addition, it may be desirable that the spacer layer 50 be manufactured so as to have a minimum level of compression recovery. The compression recovery reflects the elasticity of the material and the relative ability to maintain its thickness and void volume after compression, such as when the user / wearer is sitting. A good compression recovery may also be perceived by the user as soft and cushioning. The compression recovery may be affected by the choice of materials that make up the spacer layer. In some examples, when the spacer layer is composed of a fibrous nonwoven web material, selecting a relatively elastic fiber component may help to impart a good compression recovery. For the purposes of this article, when applying the compression recovery measurement method described herein, it may be desirable that the spacer layer be manufactured so as to exhibit a compression recovery of at least 75% of its thickness, within the feasibility of the specific material selected to make up the spacer layer.

[0096] Preferably, the spacer layer will be located below the majority, and more preferably all, of the outwardly facing surface openings of the holes 31, 32 present in the absorbent layer 30. This is to ensure that unabsorbed fluid discharged through the holes is captured by the spacer layer, rather than having a passage to the space between the top sheet and the back sheet, which may increase the risk of rewetting the top sheet. At the same time, it is preferred that the spacer layer does not have any portion extending beyond the peripheral edge of the absorbent layer. This is to ensure that the entire wearer-facing surface of the spacer layer 50 faces the outwardly facing surface of the absorbent layer 30, so that the fluid in the spacer layer 50 can be more easily absorbed by the absorbent layer 30.

[0097] Thus, it may be desirable for the spacer layer 50 to have an outer perimeter that substantially matches the absorbent layer 30. However, noting that the foam absorbent layer 30 and the spacer layer 50 may be produced by substantially different manufacturing techniques, it may be desirable for the spacer layer 50 to have an outer perimeter that is laterally and longitudinally inside the outer perimeter of the absorbent layer 30. In the same example, for purposes of manufacturing efficiency, the spacer layer 50 may have an outer perimeter that is substantially rectangular, such as Figure 2A , Figure 2B and Figure 5 However, as also indicated in these figures, the spacing layer 50 may be sized, shaped and positioned to completely underlie all of the holes 31 , 32 in / through the absorbent layer 30 .

[0098] Particularly when the spacer layer 50 is given a size and surface area that is smaller than the size and surface area of ​​the absorbent layer 30, as illustrated, it may be desirable to adhere or bond the spacer layer in an appropriate position relative to the absorbent layer to maintain it in its intended position below the apertures. In some examples, the spacer layer 50 may be adhered directly to the underside (the side facing outward) of the absorbent layer 30. This may be achieved by a deposit or pattern of deposits of adhesive disposed between the layers 30, 50. In order to ensure that the fluid passage provided to the spacer layer 50 by the apertures 31, 32 is not blocked by such adhesive deposits in the intended fluid discharge location, it may be desirable to position the adhesive primarily around the peripheral region 50p of the spacer layer, i.e., the outer boundary 51 (at Figure 5 ). The boundary 51 equally divides the distance between the outer peripheral edge of the spacer layer 30 and the intersection of the longitudinal axis 100 and the lateral axis 200.

[0099] Alternatively or in addition, the spacer layer 50 may be adhered to the backsheet 40 via a deposit or pattern of deposits of adhesive disposed between the layers 50, 40. In this location, such adhesive will not block the flow of fluid 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 a deposit of adhesive, as described above, may help ensure that these layers remain in close proximity or even face-to-face contact through the constant changes in the wearer's body movements, thereby better ensuring that fluid can easily move from the apertures 31, 32 into the spacer layer.

[0100] Negatives

[0101] The backsheet 40 may be positioned below or near the outwardly facing surface of the spacer layer 50 and may be coupled to the spacer layer by any suitable attachment method. For example, the backsheet 40 may be secured to the spacer layer 50 by a uniform continuous adhesive layer, a patterned adhesive layer, or a series of separate adhesive lines, spirals, or spots. Additionally, the attachment method may include heat bonding, pressure bonding, ultrasonic bonding, dynamic mechanical bonding, or any other suitable attachment mechanism or combination thereof. In other examples, it is contemplated that the absorbent layer 30 is not directly coupled to the backsheet 40.

[0102] Backsheet 40 can be made to be impermeable to liquid (e.g., urine, menstrual fluid) under the common use conditions of the feminine sanitary pads contemplated herein, and can be made of plastic film, but other flexible liquid-impermeable materials can also be used. Backsheet 40 can prevent or at least substantially inhibit the fluid absorbed and contained in absorbent layer 30 from escaping and reaching products such as underwear, outerwear, bedding, etc., which may contact the wearer's clothes of pad 10. However, in some cases, backsheet 40 can be made and / or adapted to allow steam to pass through (i.e., backsheet can be made breathable), while in other cases, backsheet 40 can be made to not allow steam to pass through (i.e., made airtight). Therefore, backsheet 40 can include polymer films, such as thermoplastic films of polyethylene or polypropylene. Suitable materials for backsheet 40 are, for example, thermoplastic films having a thickness of about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mil). It is contemplated herein that any suitable liquid-impermeable backsheet material known in the art is present.

[0103] Some suitable examples of backsheet materials are described in US 5,885,265, US 4,342,314 and US 4,463,045. Suitable single layer breathable backsheets for use herein include those described in, for example, GB A 2184389, GB A 2184 390, GBA 2184 391, US 4,591,523, US 3 989 867, US 3,156,242, WO 97 / 24097, US 6,623,464, US 6,664,439 and US 6,436,508.

[0104] The backsheet may be composed of two layers: a first layer comprising a breathable apertured formed film layer and a second layer comprising a breathable microporous film layer, as described in US 6,462,251. Other suitable examples of double or multilayer breathable backsheets for use herein include those described in US 3,881,489, US 4,341,216, US 4,713,068, US 4,818,600, EP 203 821, EP 710471, EP 710 472 and EP 0 793952.

[0105] Permeability measurement method

[0106] The method enables the permeability of a material (in Darcy) to be calculated, via measurement of the downward movement of a test fluid through a test specimen in the z-direction (vertical direction), within the range of the falling head indicated by the reduced height of the test fluid in the container. The reduced height of the test fluid within the container is measured repeatedly over time during the procedure as the fluid is discharged from the bottom of the container through the test specimen. From the data collected and the relevant dimensions of the portion of the equipment through which the fluid moves, the measured wet thickness of the test specimen, and constants related to gravity and the properties of the selected test fluid, flow rate and permeability can be calculated. All measurements are made in a laboratory maintained at 23°C ± 2°C and 50% ± 2% relative humidity, and the specimens are conditioned in this environment for at least 2 hours prior to testing.

[0107] Equipment parts

[0108] Measuring device 600 and its components FIG. 7A to FIG. 9 See Fig. 7A , the device 600 includes a cylindrical fluid container 601, which includes a cylindrical wall 601a, the cylindrical wall having a mating cover 602 and a base 603 that is sealingly fitted to the bottom of the wall 601a to form the fluid container 601; a fluid height sensor 606, which is fitted in the cover 602 and passes through the cover; a valve 607, which is housed in a valve body 608; and a valve actuator 610, which is mechanically associated with the valve via a connecting rod 609.

[0109] The cylindrical wall has an internal height Hfv of 200 mm to the bottom of the cover, an inner diameter of 3-7 / 8 inches (98.425 mm), a wall thickness of 3 / 8 inches (9.525 mm), and an outer diameter of 4-5 / 8 inches (117.48 mm). The cover 602 is suitably fitted to rest stably on top of the cylindrical wall, but it should not fit sealingly thereon; one or more vent holes (not shown) are drilled therethrough to prevent negative pressure / vacuum from being created within the fluid container when the test fluid is drained therefrom. The purpose of the cover 602 is to hold and suspend the fluid level sensor 606 above the test fluid surface, not to seal the container at the top.

[0110] Still see Fig. 7A , the base 603 has planar, parallel upper and lower surfaces, and the upper surface is sealingly fixed to the bottom of the wall 601a. ​​The base 603 is appropriately formed or processed to define a sample chamber having a cylindrical upper chamber portion 603a, a cylindrical middle chamber portion 603b and a cylindrical lower chamber portion 603c therein. The three cylindrical chamber portions are coaxial along the vertical / z direction.

[0111] The heights and inner diameters of the three chamber sections are as follows:

[0112] Upper chamber part 603a height Huc: 9.5mm;

[0113] The inner diameter of the upper chamber part 603a Duc: 40mm;

[0114] The height Hmc of the middle chamber part 603b is 12.5 mm;

[0115] The inner diameter Dmc of the middle chamber part 603b is 30 mm;

[0116] Lower chamber portion 603c height Hlc: 20 mm; and

[0117] The inner diameter Dlc of the lower chamber part 603a is 26mm.

[0118] A valve body 608 having a valve 607 is mounted to the lower side of the base 603, below the lower open end of the lower chamber 603c. The valve 607 is configured to be actuated quickly between a fully closed position and a fully open position, wherein in the open position, the entire lower chamber portion 603c is opened to allow fluid to move freely downward from it without any restriction of the valve 607. The valve 607 can be a flat horizontal sliding member having a circular opening port with a diameter of at least 26.0 mm passing therethrough, which moves linearly to a position below the lower chamber portion 603c when actuated to the open position. Alternatively, the valve 607 and the valve body 608 may have any other suitable configuration suitable for rapid movement between a fully closed position and a fully open position, wherein when in the fully open position, the valve does not cause any obstruction to the downward flow of the fluid and outflow from the lower open end of the lower chamber portion 603c. The valve 607 and the actuator 610 are configured to achieve actuation from a fully closed position to a fully open position in no more than 10 milliseconds, and vice versa. The actuator 610 may include a solenoid or any other suitable mechanism for this purpose.

[0119] The cylindrical wall 601a, cover 602, base 603, and optionally valve body 608 and valve 607 are fabricated and machined from a 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 various precast tube, rod / bar, disc, sheet, and block forms from various suppliers of such materials (such as McMaster-Carr Supply Company, Elmhurst, Illinois). For the tubing used to form the wall 601a, tubing having an inner diameter Dfv slightly different from the inner diameter Dfv specified herein may be selected based on availability; in such a case, it will be appreciated that in the following formula, the corresponding value of the radius r of the fluid container will be altered to reflect the actual diameter Dfv of the tubing used.

[0120] The fluid height sensor 606 is an ultrasonic height sensor, such as ML series part #098-10060, continuous transmitter through air with approximately +0.2 mm accuracy (TE Connectivity, Schaffhausen, Switzerland and Berwyn, Pennsylvania, USA) or equivalent, interfaced with a computer running software capable of collecting fluid height versus time data at a rate of 100 Hz throughout the test. The fluid height sensor 606 continuously transmits a signal indicating the height of the test fluid within the fluid container 601 during the measurement procedure.

[0121] The apparatus also 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 / perpendicular and the bottom of the base 603 horizontal. Where included, the support platform 611 must include an opening or otherwise be configured to not obstruct the lower end of the lower chamber portion 603c or the exit of fluid from the valve and valve body 607, 608.

[0122] The measuring device further comprises a collecting container 613 of any suitable shape, size and material composition adapted to receive and stably contain the entire volume of the test fluid used in the method and to fit easily under the support structure.

[0123] The measuring device also includes a sample weight 604, which is machined from stainless steel. FIG. 8A to FIG. 8C Configuration and dimensions shown. The small radially inwardly projecting lip on the top portion of the sample weight 604 is for the purpose of providing a gripping feature to facilitate placement and removal of the sample weight 604 into and from the sample chamber.

[0124] The measuring device also includes a sample support 605 having Fig. 9 The sample support 605 has a z-direction thickness of 0.75 mm (this is its height when placed into position within the measurement apparatus in preparation for a measurement procedure). Fig. 9 Each of the concentric ring portions 605a and radial spoke portions 605b of the illustrated sample support 605 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 having suitable strength and corrosion resistance, such as, for example, brass sheet stock.

[0125] It is noted that the outer diameter of the sample support 605 and the inner diameter of the intermediate chamber portion 603b are both specified as 30.0 mm as above. During the measurement procedure, the sample support 605 is disposed within the intermediate chamber 603b. Therefore, it should be 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 need to be slightly adjusted to provide a small but sufficient clearance so that the sample support 605 can be conveniently inserted into and removed from the intermediate chamber portion 603b.

[0126] Similarly, the outer diameter of the lower portion of the sample weight 604 and the inner diameter of the intermediate chamber portion 603b are both specified as 30.0 mm as above; and the outer diameter of the upper portion of the sample weight 604 and the inner diameter of the upper chamber portion 603a are both specified as 40.0 mm. During the measurement procedure, the lower portion of the sample weight 604 is disposed within the intermediate chamber portion 603b, and the upper portion of the sample weight 604 is disposed within the upper chamber portion 603a. Therefore, it should be understood that one or both of the inner diameter of the intermediate chamber portion 603b and the outer diameter of the lower portion of the sample weight 604 and one or both of the inner diameter of the upper chamber portion 603a and the outer diameter of the upper portion of the sample weight 604 may need to be slightly adjusted to provide a small but sufficient gap so that the sample weight 605 can be conveniently inserted into and removed from the intermediate chamber portion 603b.

[0127] The measurement device also includes a computer (not shown) with suitable software and docking equipment that is configured to communicate with the valve actuator 610 to effectuate the opening and closing of the valve 607, and to receive and collect fluid height data at a rate of 100 Hz over time from the fluid height sensor 606. One of ordinary skill in the art will have sufficient knowledge and / or readily available resources to obtain components and configure a system including a computer and software to perform the operations described herein.

[0128] Test fluid preparation

[0129] The test fluid used for this measurement method is an aqueous solution of sodium chloride (NaCl) with a concentration of 0.9 wt%.

[0130] The components required for the preparation of the saline test fluid include NaCl (reagent grade, CAS 7647-14-5) and deionized water. NaCl may be obtained from any convenient source, such as Sigma Aldrich item S9888.

[0131] The following preparation steps will produce 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.

[0132] Measurement procedure

[0133] To obtain test specimens for measurement, lay a single layer of dry target material flat on a horizontal work surface and die-cut a circular test specimen with a diameter of 30 mm from it. When selecting locations for sampling, avoid areas of the material with creases, wrinkles or tears.

[0134] If the subject material is a layer component of an absorbent article (e.g., a feminine sanitary pad), such as a top sheet or an absorbent layer component, a representative sample of the subject material not incorporated into the absorbent article is obtained. Alternatively, if only fully manufactured absorbent articles are available as a source of the subject material, the subject layer component is separated from the article without stretching or damaging it according to its example. Once the subject layer component has been removed from the article, a test specimen is punched out as described above. Prior to testing, the test specimen is preconditioned for 2 hours at about 23°C ± 2°C and 50% ± 2% relative humidity.

[0135] See also Figure 7B , with the fluid valve 607 in the closed position, insert the sample support 605 into the middle chamber portion 603b so that it lies horizontally / flatly on the lower circumferential lip of the middle chamber portion 603b. Using tweezers, gently place the test specimen 616 on the sample support 605 so that it lies flat on the sample support without wrinkles. Now gently place the sample weight 604 over / on top of the test specimen 616 so that the lower portion of the weight 604 is inserted into the middle chamber portion 603b and rests on the test specimen around its circumferential edge, and the upper portion of the weight 604 is nested into the upper chamber portion 603a.

[0136] The previously prepared test solution is now slowly added to the fluid container 601 until an initial fluid surface 614 height Hi of 150 mm above the upper surface of the test specimen 616 is reached.

[0137] Allow the test specimen 616 to equilibrate in the filled sample chamber for approximately 60 seconds, and ensure that no bubbles are present on the surface of the test fluid or on the surface of the test specimen. If bubbles are present on the surface of the fluid, remove or pop them using a clean instrument. If bubbles are present on the upper surface of the test specimen 616, use a clean, round-tipped laboratory stirring rod to gently dislodge them, being careful not to dislodge fibers (if the test specimen is fibrous), or to stretch or damage the test specimen.

[0138] The fluid level sensor 606 is secured to the cover 602, and the cover 602 is then placed and fitted onto the cylindrical wall 601a. ​​If necessary, the position of the fluid level sensor 606 is adjusted before the test begins to prevent it from contacting the starting surface of the test fluid. Initially, the lower tip of the sensor 606 should be approximately 170 mm from the upper surface of the test specimen 616.

[0139] A collection container 613 is positioned below valve 607 .

[0140] See now Figure 7C , to start the measurement, open valve 607 at the same time and begin collecting falling fluid height Hd and time data at a data collection rate of 100 Hz, accurate to 0.01 mm and 0.01 seconds, respectively. The test fluid will flow through the sample chamber under gravity and through the test specimen 616, the sample support 605 and the open valve 607, down into the collection container 613, and the test fluid surface 614 will drop, while the surface 615 of the collection fluid will rise. Over time, the height sensor 606 will sense and transmit data about the height of the test fluid surface 614 at the specified sensing frequency. When the test fluid has stopped leaving the valve, or after 1,000 seconds has passed, whichever occurs first, the measurement ends and the valve 607 is closed. Remove the cover 602. Lift the sample weight 604 from the sample chamber and remove it, and use tweezers to gently remove the wet test specimen 616 from the sample chamber, and continue to measure the wet thickness of the test specimen.

[0141] The wet thickness of the test sample 616 is measured immediately after the measurement procedure is completed using a manually operated micrometer equipped with a pressure foot capable of applying a stable pressure of 2.07 kPa + 0.07 kPa. The manually operated micrometer is a static heavy instrument with a reading accuracy of 0.01 mm. A suitable instrument is a Mitutoyo series 543 ID-C Digimatic purchased from Avantor / VWR International (Radnor, Pennsylvania), or an equivalent. The pressure foot is 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 pressure foot. The micrometer is zeroed for the horizontal flat reference platform. The wet test sample 616 is transferred to the reference platform of the micrometer so that the sample 616 is centered and placed horizontally and flatly below the pressure foot. The pressure foot is lowered by hand at a rate of descent of 3 + 1 mm / s until the full pressure (2.07 kPa) is applied to the test sample. After 5 seconds, record the thickness of the wet test specimen as the specimen thickness to the nearest 0.01 mm. The test specimen is then discarded.

[0142] The test fluid inside the fluid container 601 and the sample chamber is removed, if any remains therein.

[0143] Repeat this procedure for a total of three replicate test specimens.

[0144] A separate "blank" run measurement is performed by following the above procedure, but with only the sample support 605 and sample weight 604 present in the sample chamber (i.e., no test specimen is present). Note that the initial test fluid height Hi will be 150 mm above the upper surface of the sample support 605, rather than above the specimen surface. This blank measurement will enable the permeability of the sample support 605 to be taken into account when calculating the permeability of the test specimen.

[0145] Permeability calculation

[0146] Total permeability k 总 It is the permeability of the test specimen plus the sample support, calculated from the time and volume of flow through the fluid height from 150mm test fluid to 130mm test fluid. Calculate the total permeability of each repeated test specimen using the following formula and record it to the nearest 0.01E -10 m 2 :

[0147]

[0148] Therefore, solving for k 总 :

[0149] in:

[0150] Hi = initial test fluid height (150mm)

[0151] Hd = Test fluid height dropped at time t (for this calculation this is 130 mm)

[0152] t = time (seconds) when the fluid height has dropped to 130 mm

[0153] k 总 = Combined permeability of test specimen and sample support

[0154] ρ = density of the test fluid (kg / m 3 )

[0155] g = gravity constant (9.81 m / s 2 )

[0156] μ = viscosity of the test fluid (for the purposes of this article, assume 0.00109 kg / ms)

[0157] L 总 = Combined thickness of wet test specimen and sample support (m)

[0158] R = radius of the test specimen surface area through which the fluid flows ((26mm / 2) x (1m / 1,000mm) = 0.013m)

[0159] r = radius of the fluid container interior ((98.425mm / 2) x (1m / 1,000mm) = 0.049213m)

[0160] The permeability k of the sample support 605 was calculated in a similar manner from the time and volume of flow through the fluid height as it was reduced from 150 mm of test fluid to 130 mm of test fluid in a "blank" run. ssup The permeability of the individual sample supports 605 is described by the following equation and is reported to the nearest 0.01E -10 m 2 :

[0161]

[0162] Therefore, solving for k ssup :

[0163] in:

[0164] L ssup =Thickness of sample support 605 (0.00075 m)

[0165] The permeability k of each repeated test specimen 试样Calculate using the following formula and then multiply by 1.01324998E +12 And record, accurate to 0.1 Darcy:

[0166]

[0167] Now calculate the test specimen permeability k across all three replicate test specimens 试样 The arithmetic mean of the values ​​is reported as the permeability to the nearest 0.1 Darcy.

[0168] Compression recovery and dry thickness measurement methods

[0169] The compression recovery measurement method measures the compression recovery behavior of the test specimen along the z direction using a load cell on a constant velocity extension (CRE) universal mechanical testing system (a suitable instrument is MTS Alliance using TestSuite software, available from MTS Systems Corp., Eden Prairie, MN), with the measured force being within 1% to 99% of the limit value of the sensor (preferably 100N).

[0170] In this procedure, a sample of the subject material is slowly compressed along the z-direction to a maximum pressure of 3,446 Pa (0.5 psi) and then slowly released from the compression. Its initial thickness under a light contact compression of 39.79 Pa (0.0058 psi) is measured at the beginning of the loading portion of the cycle, and its final thickness under the same light contact compression is measured at the end of the unloading portion of the cycle. The final thickness divided by the initial thickness, multiplied by x100%, is the compression recovery of the material for the purposes of this article.

[0171] All tests were conducted in a room controlled at 23°C ± 3°C and 50% ± 2% relative humidity, and the test specimens were conditioned in this environment for at least 2 hours prior to testing.

[0172] The upper and lower fixtures of the test system are circular parallel plate compression platens made of stainless steel. The platen mounted on the movable CRE fixture has a diameter of 40mm and the platen mounted on the fixed CRE fixture has a diameter of >40mm. Both platens have adapters compatible with the CRE test machine bracket, which can fix the platens so that their opposing surfaces lie along parallel planes orthogonal to the CRE test machine crossbar movement.

[0173] In order to obtain the test specimen for measurement, the subject material of monolayer drying is laid flat on a horizontal work surface, and a circular specimen with a diameter of 40mm is die-cut therefrom. When selecting a location for sampling, avoid the subject material area with creases, wrinkles or tears. If the subject material is a layer component of an absorbent article (e.g., a sanitary pad for women), such as a top sheet or an absorbent layer component, a representative sample of the subject material not incorporated into the absorbent article is obtained. Alternatively, if only the absorbent article manufactured completely can be used as the source of the subject material, then according to its example, the subject layer component is separated from the article without stretching or damaging it. Once the subject layer component has been removed from the article, the test specimen is punched out as described above. The test specimen is weighed and recorded as dry mass, accurate to 0.001g. Five specimens are prepared in total. Before testing, the test specimen is preconditioned for 2 hours at a relative humidity of about 23°C ± 2°C and 50% ± 2%.

[0174] Prepare a universal test frame for compression testing to measure force and distance for one loading (compression) and unloading (recovery) cycle as follows. The crosshead motion is programmed so that the upper platen moves downward relative to the lower platen from the starting position at a rate of 0.025 mm / s until an end-point load of 4.33 N is reached (which applies an end-point pressure of 3,446 Pa (0.50 psi) between the platens), after which the crosshead motion is reversed and the upper platen is raised 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 the crosshead and load cell are then zeroed. Place the test specimen on the lower platen with the wearer-facing surface facing up and centered below the upper platen. Start the compression / release cycle and continuously collect force (N), time (s), and displacement (mm) data at a rate of 50 Hz.

[0175] The initial thickness of the test specimen was calculated from 25.0 mm to the nearest 0.001 mm by subtracting the crosshead displacement recorded under light contact compression of 0.05 N force (39.79 Pa (0.0058 psi) pressure between the platens) during the loading / compression portion of the cycle.

[0176] The temporary thickness of the test specimen is calculated from 25.0 mm to the nearest 0.001 mm by subtracting the crosshead displacement recorded during the loading / compression portion of the cycle at 0.8665 N force (689.5 Pa (0.10 psi) pressure between the platens). For the purposes of this article, this calculated value is the dry thickness of the specimen.

[0177] The final thickness of the test specimen was calculated from 25.0 mm to the nearest 0.001 mm by subtracting the crosshead displacement recorded during the unloading / recovery portion of the cycle at a light contact pressure of 0.05 N force (39.79 Pa (0.0058 psi) between the platens).

[0178] Calculate the compression recovery of the specimen as follows:

[0179] Compression recovery rate = (final thickness / initial thickness) x 100%

[0180] This procedure is repeated for each of the five test specimens and the corresponding averages of the resulting values ​​are calculated and recorded as Dry Thickness (average of the five test specimens) and Compression Recovery (average of the five test specimens).

[0181] Based on the above disclosure, the following embodiments are contemplated herein:

[0182] 1. A feminine sanitary pad (10), comprising a liquid-permeable top sheet (20), a liquid-impermeable bottom sheet (40), and an absorption system disposed between the top sheet and the bottom sheet, the absorption system comprising:

[0183] an absorbent foam layer (30) underlying the topsheet, the foam layer having a wearer-facing surface and an outward-facing surface, and a plurality of apertures (31, 32) providing z-direction access from the wearer-facing surface to the outward-facing surface; and

[0184] a porous spacer layer (50) beneath the foam layer, and

[0185] Most, preferably substantially all, and more preferably all of the openings of the cells in the outwardly facing surface of the foam layer are located underneath.

[0186] 2. The feminine sanitary pad according to embodiment 1, wherein the spacer layer (50) comprises a collection of fibers spun from one or more thermoplastic polymer resins (polymer fibers).

[0187] 3. The feminine hygiene pad of embodiment 2, wherein a majority, preferably substantially all, and more preferably all basis weight of said assembly of fibers consists of said polymer fibers.

[0188] 4. The feminine sanitary pad of embodiment 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.

[0189] 5. The feminine hygiene pad of any one of embodiments 2 to 4, wherein the fibers are bicomponent fibers.

[0190] 6. The feminine hygiene pad of embodiment 5 wherein the bicomponent fibers are crimped or curled.

[0191] 7. The feminine hygiene pad of embodiment 5 or 6, wherein the bicomponent fibers have a sheath-core configuration.

[0192] 8. The feminine hygiene pad of embodiment 7, wherein the core component comprises PET.

[0193] 9. The feminine sanitary pad of embodiment 7 or 8, wherein the sheath component comprises PE.

[0194] 10. The feminine sanitary pad of any one of embodiments 2 to 9, wherein the polymer fibers have an average denier of at least 1, more preferably at least 2.

[0195] 11. Feminine hygiene pad according to any one of the preceding embodiments, wherein the spacer layer (50) is fixed within the pad via a deposition of adhesive.

[0196] 12. The feminine hygiene pad of embodiment 11, wherein the adhesive is disposed primarily around the peripheral region (50p) of the spacer layer.

[0197] 13. The feminine hygiene pad of embodiment 12, wherein the adhesive is primarily disposed between the spacer layer and the absorbent layer.

[0198] 14. The feminine hygiene pad of embodiment 11 wherein said adhesive is primarily disposed between said spacer layer and said backsheet.

[0199] 15. A feminine sanitary pad according to any one of the preceding embodiments, wherein the spacer layer (50) has a thickness of at least 1,000 mm. 3 of void volume.

[0200] 16. The feminine sanitary pad according to any one of the preceding embodiments, 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.

[0201] 17. A feminine sanitary pad according to any one of the preceding embodiments, wherein the spacer layer (50) has a dry thickness of not more than 3.0 mm, more preferably not more than 2.0 mm, even more preferably not more than 1.5 mm, and still more preferably not more than 1.0 mm.

[0202] 18. The feminine sanitary pad according to any one of the preceding embodiments, wherein the spacer layer (50) exhibits a compression recovery of at least 75%.

[0203] 19. A feminine sanitary pad according to any one of the preceding embodiments, wherein the holes present in the drainage area have a 3 mm 2 Up to 13mm 2 , more preferably 5 mm 2 Up to 10mm 2 The average xy plane opening area.

[0204] 20. A feminine sanitary pad according to any one of the preceding embodiments, wherein the holes present in the drainage area have a width of 1 cm per cm on the wearer-facing surface of the absorbent layer. 2 3.0 to 9.0 holes, more preferably per cm 2 4.0 to 8.0 holes, or even more preferably per cm 2 Numerical density of 5.0 to 7.0 holes.

[0205] 21. The feminine hygiene pad according to any one of the preceding embodiments, wherein the foam layer (30) comprises HIPE foam.

[0206] 22. A feminine sanitary pad according to embodiment 21, wherein the foam layer (30) has two sub-layers (30a, 30b) formed together, including a wearer-facing sub-layer having a first average pore size and an outward-facing sub-layer having a second average pore size, wherein the second average pore size is smaller than the first average pore size.

[0207] 23. A feminine hygiene pad according to any one of the preceding embodiments, wherein the material constituting the spacer layer (50) is hydrophilic, or has been treated to make its surface hydrophilic.

[0208] ***

[0209] Unless expressly excluded or otherwise limited, each document cited herein, including any cross-referenced or related patent or patent application and any patent application or patent to which this application claims priority or the benefit of, is hereby incorporated by reference in its entirety. The citation of any document is not an admission that it is prior art to any of the present invention disclosed or claimed herein, or an admission that it, by itself or in combination with any one or more of the references, proposes, suggests, or discloses any such invention. In addition, to the extent that any meaning or definition of a term in this invention conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this invention shall govern.

[0210] Although specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the present invention. Therefore, it is intended that all such changes and modifications within the scope of the present invention be covered in the appended claims.

Claims

1. A feminine sanitary pad (10), comprising a liquid-permeable top sheet (20), a liquid-impermeable bottom sheet (40), and an absorption system disposed between the top sheet and the bottom sheet, the absorption system comprising: an absorbent foam layer (30) underlying the topsheet, the foam layer having a wearer-facing surface and an outwardly-facing surface, and a plurality of apertures (31, 32) providing z-direction passages from the wearer-facing surface to the outwardly-facing surface; and A porous spacer layer (50) underlying the foam layer and underlying most, preferably substantially all, and more preferably all, of the openings of the pores in the outwardly facing surface of the foam layer.

2. A feminine sanitary pad according to claim 1, wherein the spacer layer (50) comprises a fiber assembly spun from one or more thermoplastic polymer resins (polymer fibers), and wherein a majority, preferably substantially all, and more preferably all basis weight of the fiber assembly consists of polymer fibers.

3. The feminine sanitary pad according to 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. A feminine hygiene pad according to claim 2 or 3, wherein the fibers are bicomponent fibers.

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

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

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

8. The feminine sanitary pad according to claim 6 or 7, wherein the sheath component comprises PE.

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

10. Feminine hygiene pad according to any of the preceding claims, wherein the spacer layer (50) is fixed within the pad via a deposit of adhesive.

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

12. A feminine sanitary pad according to any one of the preceding claims, wherein the spacer layer (50) has a thickness of at least 1,000 mm. 3 of void volume, and has a dry thickness of not more than 3.0 mm, more preferably not more than 2.0 mm, even more preferably not more than 1.5 mm, and still more preferably not more than 1.0 mm.

13. Feminine sanitary pad according to any one of the preceding claims, 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. A feminine hygiene pad according to any one of the preceding claims, wherein the spacer layer (50) exhibits a compression recovery of at least 75%.

15. Feminine hygiene pad according to any one of the preceding claims, wherein the material constituting the spacer layer (50) is hydrophilic or has been treated to render its surface hydrophilic.

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