Nonwovens and absorbent articles having nonwovens

Abstract

The present invention relates to a non-woven substrate having a top surface and an opposing bottom surface, the non-woven substrate comprising: an upper layer forming the top surface of the non-woven substrate, the upper layer comprising hydrophobic fibers; and a lower layer forming the bottom surface of the non-woven substrate, the lower layer comprising hydrophilic fibers, where the top surface of the non-woven substrate has a first contact angle of not less than about 90 DEG as measured according to a contact angle test, wherein the bottom surface of the nonwoven substrate has a second contact angle of less than about 90 DEG as measured according to a contact angle test, where the nonwoven substrate has a unitary structure, and where the upper layer has a thickness of no greater than about 1400 m as measured according to a thickness test.

Description

Technical Field

[0001] The present invention relates to a nonwoven and an absorbent article comprising the nonwoven. Background Art

[0002] Absorbent articles have been used as personal hygiene products, such as sanitary napkins, disposable diapers for infants, training pants for young children, and incontinence underwear for adults. Such absorbent articles are designed to absorb and contain body exudates, particularly large amounts of urine, loose stools, and / or menstrual fluids (collectively referred to as "fluids"). These absorbent articles may include several layers that provide different functions, such as a topsheet, a backsheet, and an absorbent core disposed therebetween, as well as other layers (e.g., an acquisition layer, a distribution layer, etc.) as needed.

[0003] Nonwovens are widely used as components such as constituting the top sheets of absorbent articles such as sanitary napkins, baby disposable diapers, personal care disposable diapers, etc. From the viewpoints of skin feel, dryness, comfort, absorption of discharged body fluids, and / or prevention of fluid backflow, various nonwovens have been proposed for use as the top sheets of absorbent articles.

[0004] One of the design criteria for the top sheet in an absorbent article is to reduce the amount of time that a fluid spends on the top sheet before being absorbed by the absorbent article. If the fluid remains on the surface of the top sheet for too long, the wearer may feel unpleasant moisture and discomfort may increase. Another desired quality of the top sheet is to prevent the fluid from flowing back through the top sheet and provide a dry feel. At the same time, the top sheet obtains and retains some fluid in the small capillaries that may be present between the fibers, which may be visually perceived as undesirable stains by the user of the product. Another desired characteristic of an absorbent article is to present a clean user contact surface with fewer stains.

[0005] Hydrophilic topsheets are known to exhibit faster acquisition speeds than hydrophobic topsheets, however, due to the capture or retention of fluids and / or due to the high affinity of the constituent fibers for fluids, the fluid flows back through the topsheet, so it tends to cause an unpleasant wet feeling. Therefore, absorbent articles with hydrophobic topsheets may be preferred by some consumers because they provide a dry feel and good blurring and masking benefits with respect to menstrual fluid / urine stains, however, hydrophobic topsheets only absorb fluids via capillary forces, which results in a slower acquisition speed and causes fluid leakage problems. A nonwoven topsheet having a hydrophobic upper layer and a hydrophilic bottom layer is suggested for enhancing the transfer of body fluids from the top surface of the topsheet toward the bottom surface and ultimately to the absorbent core. WO2018 / 167883 discloses an absorbent article comprising a laminated nonwoven comprising a first surface facing the wearer's skin and a second surface, the first surface comprising a hydrophobic first layer and the second surface comprising a hydrophilic lower layer. The first layer and the lower layer are thermally fused together at thermal bonding points where the laminated nonwoven has a thickness less than the thickness of the peripheral portion, and the upper layer has inter-fiber fusion bonding points where the constituent fibers of the upper layer are fused together and have a thickness less than the thickness of the peripheral portion. US20160067118A discloses an open-cell nonwoven laminate for use in an absorbent article, the nonwoven laminate comprising a hydrophobic first nonwoven layer and a hydrophilic second nonwoven layer.

[0006] There continues to be a need for a topsheet for absorbent articles that provides rapid fluid acquisition while mitigating the backflow of body fluids and reducing undesirable rewet.

[0007] There is also a need for a topsheet for an absorbent article that provides improved stain masking so that it can provide a clean user contacting surface without compromising fluid handling properties, such as rapid fluid acquisition rate and reduced rewet.

[0008] There continues to be a need for a topsheet for absorbent articles that provides a smooth and soft feel without including fluid handling properties such as fast fluid acquisition speed and reduced rewet. Summary of the Invention

[0009] The present invention provides a nonwoven substrate having a top surface and an opposing bottom surface, and comprising an upper layer forming the top surface of the nonwoven substrate and a lower layer forming the bottom surface of the nonwoven substrate, wherein the top surface of the nonwoven substrate has a first contact angle of not less than about 90° as measured according to the Contact Angle Test, wherein the bottom surface of the nonwoven substrate has a second contact angle of less than about 90° as measured according to the Contact Angle Test, and wherein the nonwoven substrate has a unitary structure, and wherein the upper layer has a thickness of not greater than about 1200 μm as measured according to the Thickness Test.

[0010] The present invention also provides an absorbent article comprising a wearer-facing surface, a garment-facing surface, a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core arranged between the topsheet and the backsheet, wherein the topsheet comprises the nonwoven substrate of the present invention, and the topsheet is arranged in such a manner that the upper layer of the nonwoven substrate forms at least a portion of the wearer-facing surface.

[0011] These and other features, aspects and advantages of the present invention will become apparent to those skilled in the art from a reading of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic diagram of a nonwoven according to the present invention having an upper layer and a lower layer.

[0013] Figure 2A is a cross-sectional image of an exemplary nonwoven of the present invention.

[0014] Figure 2B is a cross-sectional image of another exemplary nonwoven of the present invention.

[0015] Figure 3 A top view of another nonwoven fabric.

[0016] Figure 4 Schematic top view of an exemplary nonwoven constituting the topsheet.

[0017] Figure 5 is a perspective view of an exemplary absorbent article.

[0018] Figure 6 For the Figure 5 6-6 is a side cross-sectional view of the absorbent article.

[0019] Figure 7A is an image of an exemplary water droplet having a contact angle greater than 90 degrees according to the Contact Angle Test disclosed herein.

[0020] Figure 7B is an image of an exemplary water droplet having a contact angle of no greater than 90 degrees according to the Contact Angle Test disclosed herein.

[0021] Figure 8A is an image of a nonwoven sample held by an exemplary instrument for measuring the thickness of a nonwoven.

[0022] Figure 8B is an image of a nonwoven sample used to measure the thickness of the nonwoven according to the Thickness Test disclosed herein.

[0023] Figure 8C for Figure 8B1. An image of a nonwoven sample of FIG. 1 with exemplary markings for measuring the thickness of the nonwoven according to the Thickness Test disclosed herein.

[0024] Figure 9A A perspective view of the strikethrough plate used for acquisition time measurements.

[0025] Figure 9B for Figure 9A Plan view of the vapor permeable panel.

[0026] Figure 9C for Figure 9B A plan view of the 9C-9C cross section of the breathable plate.

[0027] Figure 9D for Figure 9B A plan view of the parts pf of the breathable plate.

[0028] Figure 9E for Figure 9B A plan view of the cross section of the breathable plate in the 9E-9E direction. DETAILED DESCRIPTION

[0029] All ranges are inclusive and combinable. The number of significant digits does not limit the quantity indicated nor the precision of the measurement. All numerical values ​​should be understood as being modified by the word "about" unless otherwise specifically indicated.

[0030] As used herein, the term "absorbent article" includes disposable diapers, sanitary napkins, panty liners, incontinence pads, interlabial pads, breast milk pads, sweat sheets, animal waste management products, animal diapers, and the like.

[0031] As used herein, the term "carded" is used to describe the structural features of the fluid management layer described herein. Carded nonwovens utilize fibers that are cut to specific lengths, which are otherwise referred to as "staple fibers." The staple fibers can be of any suitable length. For example, the staple fibers can have a length of up to 120 mm or can have a length as short as 10 mm. However, if a particular group of fibers are staple fibers (e.g., viscose fibers), the length of each of the viscose fibers in the carded nonwoven is primarily the same, i.e., the short length. Notably, when an additional staple-length fiber type is included, such as polypropylene fibers, the length of each of the polypropylene fibers in the carded nonwoven is also primarily the same. However, the short length of the viscose fibers and the short length of the polypropylene fibers can differ.

[0032] In contrast, continuous filaments, such as those produced by spunbond or meltblown processes, do not produce staple fibers. Instead, these filaments have an indefinite length and are not cut into specific lengths as described for their staple length counterparts.

[0033] The "longitudinal" direction is a direction extending parallel to the largest linear dimension of the article (generally the longitudinal axis), and includes directions within 45° of the longitudinal direction. As used herein, the "length" of an article or component thereof generally refers to the size / distance of the largest linear dimension, or generally refers to the size / distance of the longitudinal axis of the article or component thereof.

[0034] The "lateral" or "transverse" direction is orthogonal to the longitudinal direction, i.e., in the same principal plane as the longitudinal axis of the article, and transversely parallel to the transverse axis. As used herein, the "width" of an article or component thereof refers to the size / distance of the dimension orthogonal to the longitudinal direction of the article or component thereof, i.e., orthogonal to the length of the article or component thereof, and generally refers to the distance / size of the dimension parallel to the transverse axis of the article or component.

[0035] As used herein, the terms "hydrophilic" and "hydrophobic" have their generally accepted meanings in the art with respect to the contact angle of water on a material surface. Thus, a material having a water contact angle greater than about 90° as measured by a contact angle test is considered hydrophobic, and a material having a water contact angle less than about 90° as measured by a contact angle test is considered hydrophilic.

[0036] Nonwoven substrates

[0037] Nonwoven of the present invention comprises top surface, relative bottom surface, the upper strata that forms the top surface of nonwoven substrate and the lower strata that forms the bottom surface of nonwoven substrate.The upper strata comprises hydrophobic fiber, and the second layer comprises hydrophilic fiber.The top surface of nonwoven has as measured according to the contact angle test the first contact angle that is not less than about 90 degree, and the bottom surface of nonwoven has as measured according to the contact angle test the second contact angle that is lower than about 90 degree.Nonwoven has one-piece structure, and the upper strata has as measured according to the thickness test the thickness that is not more than about 1200 μ m.

[0038] Advantageously, when the nonwoven of the present invention is used as a topsheet of an absorbent article, it provides a fast fluid acquisition rate while maintaining preferably low rewet. The nonwoven of the present invention can provide improved dirt masking, so that it can present a clean user contact surface. In addition, the nonwoven of the present invention can provide a soft and smooth skin feel by using fine denier fibers for at least the upper layer.

[0039] Without being bound by theory, the advantageous properties of the nonwoven of the present invention may be achieved by introducing surface energy differences by having the top surface of the nonwoven have a first contact angle of not less than about 90° as measured according to the Contact Angle Test and the bottom surface have a second contact angle of less than about 90° as measured according to the Contact Angle Test, and by having the nonwoven have a unitary structure in which the upper layer has a thickness of not greater than about 1200 μm as measured according to the Thickness Test.

[0040] Hereinafter, the fibers constituting the nonwoven substrate of the present invention, the configurations of the first layer and the lower layer, and the method for manufacturing the nonwoven and the absorbent article having the nonwoven substrate are described.

[0041] See also Figure 1 When the nonwoven fabric of the present invention includes an upper layer and a lower layer, the upper layer and the lower layer form an integral structure. The integral structure herein is intended to mean that although it can be formed by several sublayers with different properties and / or compositions, they are mixed in a certain way at the boundary area where the sublayers contact each other, so that it is possible to identify the area where fibers from each sublayer coexist and different sublayers transition from one to another. That is, the integral structure material has a boundary area where the fibers from the sublayer are bonded to the fibers from the adjacent sublayer on a fiber-to-fiber level. Such an integral structure is usually constructed in the following way: each sublayer is formed on top of another in a continuous manner (for example, using air-laid or wet-laid deposition). Or each sublayer in the sublayer is produced in a separate step, and the sublayers are combined together in a face-to-face relationship. The combined sublayers can be integrated via known integration or bonding methods, such as hydroentanglement, jet-interlacing, air-through bonding and resin bonding. Typically, no adhesive is used between the sublayers of a single material. However, in some cases, an adhesive and / or binder may be present. In contrast, laminates have an interface between two adjacent layers, where void space or laminating media such as glue and molten resin exists between each layer. Such laminating media and void space negatively impact the fluid permeability and absorptive capacity of the laminate.

[0042] When describing the nonwovens of the present invention herein, the terms layer, sublayer, and layer are used interchangeably.

[0043] Figure 2A is a cross-sectional image of an exemplary nonwoven of the present invention having a first layer 1 made of 1.5 denier PE / PET fibers and a lower layer 2 made of 2 denier PE / PET fibers. The nonwoven 30 has a unitary structure, and the fibers from the upper layer 1 and the fibers from the lower layer 2 are mixed in the boundary area rather than having a clear boundary between the two layers.

[0044] Without being bound by theory, the nonwoven fabric of the present invention having an integral structure does not have a laminate interface and can avoid the negative impact on the fluid permeability and absorptive capacity of the nonwoven fabric. In addition, the hydrophilic fibers from the lower layer extend into the upper layer, and the hydrophilic fibers can enhance the fluid absorbency from the top surface.

[0045] The nonwoven fabric of the present invention optionally comprises a plurality of pores. Figure 2B, the nonwoven fabric 30 may include a top surface 32, a bottom surface 34 and a plurality of holes 5. Still referring to Figure 2B The nonwoven 30 may include a plurality of non-porous areas 8, the plurality of non-porous areas being a plurality of discrete areas defined by pores. Each of the plurality of discrete non-porous areas is defined by a perimeter formed by a continuous line of pores, wherein at least 80% or at least 90% of the pores have adjacent pores that are spaced apart by an edge-to-edge distance of no more than 3 mm.

[0046] See also Figure 8B and Figure 8C , the nonwoven substrate according to the present invention may have a boundary area in which the hydrophobic fibers from the upper layer and the hydrophilic fibers from the lower layer coexist, and the boundary area has a thickness D2 in the thickness direction of the nonwoven fabric of about 100μm, or about 150μm, or about 170μm, or about 200μm as measured according to the thickness test.

[0047] In one embodiment, the hydrophobic fiber that constitutes the upper strata has the denier that is not more than 2.0 deniers, or is greater than about 1.5 deniers, or is not more than about 1.2 deniers, or is not more than about 1.0 deniers, or about 0.8 denier.Due to the small denier fibers on the upper strata that form the top surface of nonwoven, nonwoven can provide excellent softness and smoothness.Although small denier fibers are favourable aspect giving nonwoven material softness and smoothness, they build more dense structure with less interfiber space between fiber.This type of dense structure makes nonwoven more difficult to penetrate fluid, particularly when fiber is hydrophobic.In addition, this type of dense structure makes nonwoven easier to fluid capture in nonwoven, particularly when fiber is hydrophilic. Nonwoven of the present invention can adopt small denier fibers in the upper strata, such as having the fiber of the denier that is not more than about 1.5 deniers, or is not more than about 1.2 deniers, or is not more than about 1.0 deniers, and does not compensate fluid handling characteristics. Without being bound by theory, the nonwoven of the present invention can have sufficient fluid absorption capacity despite the upper layer containing hydrophobic fibers by having a lower layer including a hydrophilic layer located below the upper layer, the lower layer creating a hydrophilicity gradient to drive fluid to penetrate from the top surface to the bottom of the nonwoven; and having an integral structure in which some of the hydrophilic fibers from the lower layer extend into the upper layer.

[0048] In this embodiment, the hydrophobic fibers constituting the upper layer may have a denier no greater than the denier of the hydrophilic fibers constituting the lower layer.

[0049] In order to achieve better absorption performance, capillary energy is a common consideration in nonwoven topsheets. In order to utilize capillary energy in the context of absorbent product design, nonwoven topsheets are described as having a capillary gradient from the top surface to the bottom surface to amplify capillary energy. The common nonwoven fabric design that produces a capillary gradient is to make the lower part of the nonwoven topsheet denser, with a smaller pore size or finer fibers than the upper part of the nonwoven topsheet. At the same time, it is preferred that the upper part of the nonwoven be formed by fine denier fibers, which can impart a soft and smooth touch. However, the use of fine denier fibers in the upper part of the topsheet limits the choice of fibers for the lower layer, which makes the lower layer have a denser structure. In addition, if the lower part of the nonwoven topsheet has a very dense structure, it is difficult to find an absorbent material with strong suction capacity arranged below the topsheet. Without being bound by theory, the nonwoven of the present invention can overcome this contradiction by introducing a surface energy gradient (i.e., by introducing a high hydrophilicity gradient from top to bottom) and making the top and bottom layers completely integrated. The apertures, including at least one aperture having at least three adjacent apertures, also play a key role in overcoming the contradiction, the at least three adjacent apertures being separated by an edge-to-edge spacing of no more than about 3 mm.

[0050] In one embodiment, the hydrophobic fibers constituting the upper layer and / or the hydrophilic fibers constituting the lower layer are short fibers. Short fibers provide greater flexibility in fiber selection than filaments, which enable desired nonwoven properties to be provided to meet various needs.

[0051] In one embodiment, nonwoven of the present invention is an air-through bonded nonwoven with an integral structure. The features of upper and lower floors fully and uniformly integrated on the fiber level can contribute to the advantageous properties of nonwoven of the present invention. In one embodiment, nonwoven of the present invention is a carded air-through bonded nonwoven with an integral structure. In another embodiment, nonwoven of the present invention is a spunbond nonwoven.

[0052] The basis weight of the nonwoven fabric of the present invention can be appropriately selected according to the application of the nonwoven fabric. The nonwoven fabric can have a basis weight of about 10 g / m 2 About 100g / m 2 , or about 35g / m 2 to about 70g / m 2 For nonwovens used as top sheets of absorbent articles, in one embodiment, the overall basis weight of the nonwoven is about 30 g / m 2 to about 70g / m 2 , or about 15g / m 2 to about 40g / m 2 , or about 12g / m 2 About 35g / m2 within the range.

[0053] In one embodiment, the nonwoven material comprises an upper layer forming the top surface of the nonwoven material and a lower layer forming the bottom surface of the nonwoven material. In this embodiment, the nonwoven material may comprise at least one intermediate layer located between the upper layer and the lower layer.

[0054] First floor

[0055] The upper layer of the nonwoven of the present invention comprises hydrophobic fibers.The upper layer may consist essentially of hydrophobic fibers.

[0056] The upper layer has a thickness of no greater than about 1200 μm, or no greater than about 1050 μm, or no greater than about 1100 μm as measured according to the Thickness Test.

[0057] The fibers constituting the upper layer may be natural fibers, synthetic fibers, or a combination of natural and synthetic fibers. In one embodiment, the upper layer comprises thermoplastic fibers.

[0058] The hydrophobic fiber can be a thermoplastic fiber selected from the group consisting of polyester, polypropylene, polyethylene, polyether, polyamide, polyhydroxyalkanoate, polysaccharide, and combinations thereof. Additionally, other synthetic fibers such as rayon, polyethylene, and polypropylene fibers may also be used within the scope of the present disclosure. The thermoplastic fiber can be a single-component fiber (i.e., a single synthetic material or a mixture thereof that constitutes the entire fiber), a multi-component fiber such as a bicomponent fiber (i.e., a fiber divided into multiple regions comprising two or more different synthetic materials or mixtures thereof), and combinations thereof.

[0059] Hydrophilic fibers can be rendered hydrophobic by treating them with a hydrophobic treatment, such as a hydrophobic surfactant, for example by spraying or kiss-roll coating the hydrophilic fibers with the hydrophobic treatment, by immersing the fibers in the hydrophobic treatment, or by including the hydrophobic treatment as part of the polymer melt in preparing the thermoplastic fibers. Upon melting and resolidification, the treatment will tend to remain at the surface of the fibers.

[0060] The upper layer may comprise semisynthetic fibers made from polymers, in particular hydroxyl polymers. The top sheet may also comprise semisynthetic fibers made from polymers, in particular hydroxyl polymers. Non-limiting examples of suitable hydroxyl polymers include polyvinyl alcohol, starch, starch derivatives, chitosan, chitosan derivatives, cellulose derivatives such as viscose, gum, arabinan, galactan, lyocell (Tencel ® ) and their combinations.

[0061] The upper layer may further comprise absorbent fibers. Some examples of absorbent fibers include cotton, pulp, rayon, or regenerated cellulose, or combinations thereof. The upper layer may further comprise cellulose-based fibers selected from the group consisting of wheat straw fibers, rice straw fibers, flax fibers, bamboo fibers, cotton fibers, jute fibers, hemp fibers, sisal fibers, bagasse fibers, yucca fibers, and combinations thereof.

[0062] Several examples of the upper layer may include, but are not limited to: spunbond nonwovens; carded nonwovens; air-carded nonwovens; hydroentangled nonwovens, needle-punched nonwovens, and nonwovens having relatively specific properties to be easily deformable.

[0063] The upper layer can be formed by a number of processes such as, for example, air laying, wet laying, melt blowing, spun bonding, needle punching, and carding.

[0064] In one embodiment, the upper layer is a carded air-through nonwoven.

[0065] The hydrophobic fibers constituting the upper layer 1 may have a contact angle of not less than about 95 degrees, or not less than about 100 degrees. According to a contact angle test, the fibers constituting the upper layer 1 may have a contact angle of not more than 150 degrees, or not more than 130 degrees. The hydrophobicity of the constituent fibers can be adjusted by appropriately adjusting the degree of hydrophobization treatment of the thermoplastic fibers, for example, the type and content of the hydrophobic treatment agent.

[0066] The hydrophobic fibers constituting the upper layer may have a fiber fineness of not more than 4 deniers, or not more than 2.5 deniers, or not more than 2 deniers, or not more than 1.5 deniers, or not more than 1.2 deniers.

[0067] The upper layer may have a thickness of about 5 g / m 2 About 20g / m 2 , or about 8g / m 2 About 15g / m 2 , about 8g / m 2 to about 12g / m 2 , or about 6g / m 2 to about 10g / m 2 basis weight.

[0068] Lower level

[0069] The lower layer of the nonwoven of the present invention comprises hydrophilic fibers.The lower layer may consist essentially of hydrophobic fibers.

[0070] The fibers constituting the lower layer may be natural fibers, synthetic fibers, or a combination of natural and synthetic fibers. In one embodiment, the lower layer comprises thermoplastic fibers.

[0071] The list of synthetic fibers corresponds to the list disclosed above for the topsheet and upper layer.

[0072] Hydrophobic fibers can be rendered hydrophilic by treating them with a hydrophilic treating agent, such as a hydrophilic surfactant, for example by spraying a hydrophobic thermoplastic with the hydrophilic treating agent, by dipping the fibers into the treating agent, or by including the hydrophilic treating agent as part of the polymer melt in preparing the thermoplastic fibers. Upon melting and resolidification, the treating agent will tend to remain at the surface of the fibers.

[0073] The hydrophilic fibers constituting the lower layer may have a fiber fineness of not more than 6 deniers, or not more than 4 deniers, or not more than 2 deniers.

[0074] The hydrophilic fibers constituting the lower layer may have a contact angle of not greater than about 90 degrees, or not greater than about 30 degrees, or not greater than about 10 degrees, or zero degrees according to a contact angle test.

[0075] The lower layer may have a thickness of about 5 g / m 2 to about 70g / m 2 , or about 10g / m 2 to about 60g / m 2 , or about 10g / m 2 to about 25g / m 2 basis weight.

[0076] Except for the lower layer comprising hydrophilic fibers, all aspects described above for the upper layer are also applicable to the upper layer in the topsheet comprising the first layer and the lower layer.

[0077] hole

[0078] Nonwoven fabric of the present invention can comprise a plurality of holes.The shape of hole can change.For example, the shape of the hole seen from the first surface of upper strata can be circular, oval, rectangular or polygonal.In one embodiment, hole has circular shape, oval shape or polygonal shape.

[0079] The three-dimensional shape of the hole may be cylindrical (eg, with a circular or oval base), prism (eg, with a polygonal base), or a truncated cone or pyramid.

[0080] The holes may be tapered and have a conical shape such that the diameter of the holes is larger at a portion of the holes adjacent the first surface of the nonwoven than at a bottom edge of the holes.

[0081] This tapered configuration helps reduce the risk of backwet, i.e., the backflow of body fluids from components beneath the topsheet (such as the absorbent core) through the topsheet. For an open-aperture hydrophobic topsheet, backwet occurs primarily through the apertures. The tapered shape of the apertures can help reduce backwet because the diameter of the apertures toward the absorbent core is smaller than the diameter of the apertures in the upper layer.

[0082] The plurality of apertures may also vary in width.

[0083] The size of the holes can be determined to achieve the desired fluid and / or air permeability and other properties desired by the wearer. If the holes are too small, fluid may not be able to pass through the holes due to misalignment between the fluid source and the location of the holes or because, for example, loose stool has a diameter larger than the holes. If the holes are too large, the area of ​​skin that can be contaminated by "rewet" from the article increases.

[0084] Each of the plurality of holes may have a diameter of 0.2 mm. 2 Up to 1.5mm 2 , 0.2mm 2 to 1.0mm 2 , or 0.25mm 2 to 0.5mm 2 The plurality of holes may have a size in the range of 0.5 to 1.5 mm, or 0.3 to 1 mm, or 0.4 to 0.8 mm. The plurality of holes may have a regular shape selected from the group consisting of: circle, oval, triangle, square, rectangle, parallelogram, trapezoid, polygon, hourglass, star, and any combination thereof.

[0085] absorbent products

[0086] The nonwoven of the present invention exhibits rapid acquisition of body fluids, keeping the top surface dry because it inhibits the body fluids from flowing back to the top surface under pressure.

[0087] Therefore, the nonwoven of the present invention can be preferably used in applications in which the nonwoven comes into contact with the skin, in particular in applications in which the upper layer constitutes the skin-contacting surface of an absorbent article.

[0088] Through consumer testing, it has been found that users of feminine hygiene pads most prefer pads configured with an absorbent structure and a topsheet that exhibits an acquisition time (expressed in seconds) of no more than 45 seconds, more preferably no more than 30 seconds, and even more preferably no more than 25 seconds for the first gush of a new pad when the pads are tested using the acquisition time measurement method described herein. Acquisition time, as measured for the purposes of this document, reflects the ability (or lack thereof) of the absorbent structure / topsheet combination to acquire fluid in the z-direction and transfer it to the absorbent structure under specific conditions. Rapid acquisition is preferred, but cannot be freely reduced without adversely increasing the topsheet's tendency to rewet. It has also been found that users of feminine hygiene pads most prefer pads configured with an absorbent structure and a topsheet that exhibits a rewet (expressed in grams) of no more than 0.6 g, more preferably no more than 0.5 g (cumulatively up to a 9 ml load). Using the nonwoven topsheets described herein, the acquisition time and rewet of an absorbent article can be reduced without sacrificing either.

[0089] Absorbent articles will now be discussed generally and further illustrated in the form of a sanitary napkin 100, as shown. Figure 5 Presented exemplarily. Figure 5 is a plan view of an exemplary sanitary napkin 100 in a flat configuration with the garment-facing side turned over. Figure 6 For the Figure 5 6-6 is a side cross-sectional view of the absorbent article.

[0090] See also Figure 5 and Figure 6 An absorbent article according to the present invention (e.g., sanitary napkin 100) includes a topsheet 24 comprising a nonwoven 30 and having a wearer-facing surface and a garment-facing surface positioned opposite the wearer-facing surface. The top surface 32 of the nonwoven 30 forms the wearer-facing surface of the sanitary napkin 100. The absorbent article also includes a backsheet 26 having a garment-facing surface and a user-facing surface positioned opposite the garment-facing surface and at least partially joined to the topsheet 24. The absorbent article also includes an absorbent core 28 positioned between the topsheet 24 and the backsheet 26. The absorbent article also includes a fluid management layer 27 positioned between the topsheet 24 and the absorbent core 28. The absorbent article may also include an additional acquisition and / or distribution layer (or system) or a secondary topsheet 25 and / or a pair of flaps or wings 23. The topsheet 24, backsheet 26, fluid management layer 27, and absorbent core 28 may be assembled in a variety of well-known configurations.

[0091] The backsheet 26 and topsheet 24 can be secured together in a variety of ways. The topsheet 24 and backsheet 26 can be joined to each other using adhesive heat bonds, pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or crimp seals. Fluid-impermeable crimp seals prevent lateral migration of fluids through the edges of the product ("wicking"), thereby inhibiting side soiling of the user's undergarment.

[0092] When the absorbent article is Figure 5 When the sanitary napkin is shown, as is typical for sanitary napkins and the like, the sanitary napkin may have panty adhesive disposed on the garment-facing side of the backsheet 26. The panty adhesive may be any adhesive known in the art for this purpose and may be covered with a release paper prior to use, as is well known in the art. If side flaps or wings are present, the panty adhesive may be applied to the garment-facing side so as to contact and adhere to the underside of the user's panties.

[0093] The absorbent article according to the present invention comprises a topsheet and a liquid-impermeable backsheet, and an absorbent core arranged between the topsheet and the backsheet, wherein the topsheet comprises the nonwoven according to the present invention.

[0094] The absorbent article of the present invention can be industrially produced by any suitable method.Thus, the different layers can be assembled using standard methods such as embossing, thermal bonding, gluing or any combination thereof.

[0095] Nonwoven fabric manufacturing method

[0096] The nonwoven according to the present invention can be produced via various methods known in the industry.

[0097] The upper layer and the lower layer can be prepared separately and bonded or integrated together, for example, via heat application and / or glue application. Each of the upper layer and the lower layer can be from a carded fiber web, an air-laid fiber web, a wet-laid fiber web, a spunbond fiber web, etc.

[0098] The nonwoven fabric according to the present invention can be manufactured in a continuous process. For example, a first web comprising hydrophobic fibers is placed on a conveyor belt, a second web comprising hydrophilic fibers is overlaid on the first web to obtain a composite web, and the composite web is subjected to a heat treatment to thermally bond at least a portion of the hydrophobic fibers and the hydrophilic fibers to prepare the nonwoven fabric. In other embodiments, a parallel carding machine is used to prepare the nonwoven fabric by a method comprising the following steps: forming a first web comprising hydrophobic fibers, forming a second web comprising hydrophilic fibers, forming a composite web by overlaying the second web on the first web; and subjecting the composite web to a heat treatment to thermally bond at least a portion of the hydrophobic fibers and the hydrophilic fibers.

[0099] The bonding treatment of the synthetic fiber web can be carried out using any conventional known fiber bonding method. Examples of such bonding methods include heat-through-air thermal bonding and ultrasonic bonding.

[0100] The aperturing of the precursor nonwoven can be performed using any conventional known nonwoven aperturing method. An exemplary aperturing apparatus is a pair of rollers comprising a pair of rollers.

[0101] Measurement

[0102] 1. Contact angle test

[0103] All tests were conducted in a laboratory maintained at 23°C ± 2°C and 50% ± 2% relative humidity.

[0104] Cut a rectangular sample measuring 10 mm x 50 mm from the raw nonwoven or the topsheet of a disposable absorbent article, taking care not to touch the sample surface or damage the material structure. The sample should be 5 cm long and, if cut from an absorbent article, aligned with the longitudinal centerline of the absorbent article. Use clamps to gently grasp the edges of the sample and mount it flat on the sample stage of an optical microscope (such as a Keyence VHX 5000 or equivalent). Adjust the appropriate light source, magnification, and camera position to clearly display the cross-sectional view of the sample.

[0105] A water droplet of about 0.05 ml is gently deposited onto the sample from a close distance of no more than 1 cm above the surface being tested of the sample. A Keyence VHX 5000 or equivalent is used to obtain a high-resolution image of the water droplet on the surface being tested of the nonwoven sample. These steps are repeated to obtain multiple water droplet images. A suitable water droplet image is one in which each water droplet is oriented so that the projection of the water droplet extending from the nonwoven surface is approximately maximized. The contact angle between the water droplet and the sample is measured directly from the captured image (accurate to 0.1 degrees), as shown in FIG. Figure 7A and Figure 7B As shown in line 3700 in FIG. Figure 7A is an exemplary image of a water droplet with a contact angle greater than 90°. Figure 7B is an exemplary image of a water droplet with a contact angle less than 90°.

[0106] Measurements were performed on an area of ​​the test nonwoven where no pores were present. Five separate water droplets were imaged, from which ten contact angles were measured—one contact angle measured on each side of each imaged droplet. The arithmetic mean of the ten contact angle values ​​was calculated (to the nearest 0.1 degree) and reported as the surface contact angle.

[0107] 2. Nonwoven thickness test

[0108] When the nonwoven is available in raw material form, a fairly smooth sample of 10 mm x 50 mm is cut from the raw material nonwoven. When the nonwoven is a component of a finished product, a sample is removed from the component of the nonwoven in the finished product using a razor blade to provide a fairly smooth sample of 10 mm x 50 mm, taking care not to touch the surface of the sample or disturb the structure of the material. A low temperature spray (such as Sunto ™ Freeze spray, Sunto (HK) International, China) to remove samples from other parts of the final product.

[0109] The sample is placed in an oven at a temperature of 80°C to 90°C for about 30 seconds to 60 seconds, until the thickness of the sample no longer increases over a longer period of time.

[0110] See also Figure 8A , gently hold the edges of the specimen with clamps, and mount it flat with the upper layer facing up by inserting each side of the specimen into the clamps, taking care to secure it without stretching the specimen. The cross section of the specimen is oriented horizontally to facilitate image acquisition under a magnifying microscope (such as a Keyence VHX 5000 or equivalent). Select the appropriate magnification and light source of the equipment so that the cross section of the specimen is clearly visible. See Figure 8A , use a syringe to gently place a colored water droplet of approximately 0.01 ml on the first area of ​​the bottom surface 34 of the sample. Wait for the water droplet to be absorbed into the sample. Repeat by placing a colored water droplet of approximately 0.01 ml in an area adjacent to the first area and wait for the water droplet to be absorbed into the sample. Repeat these steps until the length ("La") of the colored segment portion 800 where water is absorbed is at least 10 mm, and the image is taken as shown. Figure 8B Image of a cross-sectional view.

[0111] See also Figure 8C , in the focused view of the sample 30, draw a line 1 ("L1") that contacts the top surface 32 of the sample 30. Draw a line 2 ("L2") that is parallel to L1 and at the center 80% "La" of the colored segment portion 800. 80% ” contacts the highest point of the colored segment portion 800 at the center. Draw line 3 (“L3”) parallel to L1 and contacting the lowest point of the upper surface of the colored segment portion 800 at 80% of the center of the colored segment portion 800. Draw line 4 (“L4”) that bisects the distance between L2 and L3. Measure the distance D1 between L1 and L4 and the distance D2 between L2 and L4.

[0112] In a similar manner, test a total of three replicates for each nonwoven to be evaluated. Calculate the arithmetic mean (to the nearest 1 µm) of the replicates D1 and record this as the upper layer thickness. Calculate the arithmetic mean (to the nearest 1 µm) of the replicates D2 and record this as the border zone thickness.

[0113] Such methods are performed on non-porous areas of the nonwoven to measure layer thickness.

[0114] 3. Preparation of Artificial Menstrual Fluid ("AMF")

[0115] AMF consists of a mixture of defibrinated sheep blood, phosphate buffered saline solution and mucus components and has a viscosity between 7.15 cSt and 8.65 cSt at 23°C ± 1°C.

[0116] Viscosity on AMF was measured using a low-viscosity rotational viscometer, such as a Cannon LV-2020 Rotary Viscometer (Cannon Instrument Co., State College, US) with a UL adapter, or equivalent. A spindle of appropriate size within the viscosity range was selected, and the instrument was operated and calibrated according to the manufacturer. Measurements were taken at 23°C ± 1°C and 60 rpm. Results were reported to the nearest 0.01 cSt.

[0117] Defibrinated sheep blood

[0118] Defibrinated sheep blood (purchased from Cleveland Scientific, Inc., Bath, OH, US) or equivalent collected under sterile conditions and having a packed cell volume of 38% or greater was used.

[0119] Phosphate-buffered saline solution

[0120] Phosphate-buffered saline solution consists of two separately prepared solutions (Solution A and Solution B). To prepare 1 L of Solution A, add 1.38 ± 0.005 g of sodium dihydrogen phosphate monohydrate and 8.50 ± 0.005 g of sodium chloride to a 1000 mL volumetric flask and bring to volume with distilled water. Mix thoroughly. To prepare 1 L of Solution B, add 1.42 ± 0.005 g of anhydrous sodium dihydrogen phosphate and 8.50 ± 0.005 g of sodium chloride to a 1000 mL volumetric flask and bring to volume with distilled water. Mix thoroughly. Add 450 ± 10 mL of Solution B to a 1000 mL beaker and stir at low speed on a stir plate. Insert a calibrated pH probe (accurate to 0.1) into the beaker containing Solution B and, while stirring, add enough Solution A to bring the pH to 7.2 ± 0.1.

[0121] Mucus components

[0122] The mucus component is a mixture of phosphate-buffered saline solution, potassium hydroxide solution, gastric mucin, and lactic acid solution. The amount of gastric mucin added to the mucus component directly affects the final viscosity of the prepared AMF. A successful range for gastric mucin is generally between 38 and 50 grams. To prepare approximately 500 mL of the mucus component, add 460 ± 10 mL of the previously prepared phosphate-buffered saline solution and 7.5 ± 0.5 mL of 10% w / v potassium hydroxide solution to a 1000 mL heavy glass beaker. Place the beaker on a stirring hot plate and, while stirring, bring the temperature to 45°C ± 5°C. Weigh a predetermined amount of gastric mucin (± 0.50 g) and slowly sprinkle it into the previously prepared liquid, which has reached 45°C, without clumping. Cover the beaker and continue mixing. Within 15 minutes, bring the temperature of the mixture above 50°C, but not exceeding 80°C. While maintaining this temperature range, continue heating with gentle stirring for 2.5 hours, then remove the beaker from the hot plate and cool to below 40°C. Next, add 1.8 ± 0.2 mL of a 10% v / v aqueous lactic acid solution and mix thoroughly. Autoclave the mucus fraction mixture at 121°C for 15 minutes and cool for 5 minutes. Remove the mucus fraction mixture from the autoclave and stir until the temperature reaches 23°C ± 1°C.

[0123] Allow the sheep blood and mucus components to reach a temperature of 23°C ± 1°C. Using a 500mL graduated cylinder, measure the volume of the entire batch of mucus components and add it to a 1200mL beaker. Add an equal amount of sheep blood to the beaker and mix thoroughly. Using the viscosity method described previously, ensure that the viscosity of the AMF is between 7.15 cSt and 8.65 cSt. If not, dispose of the batch and make another batch as needed for adjusting the mucus component.

[0124] Unless intended for immediate use, qualified AMF should be refrigerated at 4°C. After preparation, AMF may be stored in an airtight container at 4°C for up to 48 hours. Prior to testing, the AMF must be allowed to reach 23°C ± 1°C. After testing, discard any unused portion.

[0125] 4. Back-infiltration test

[0126] Rewet is measured for absorbent articles loaded with artificial menstrual fluid (AMF) as described herein.

[0127] After dispensing 3.0 ml, 6.0 ml and 9.0 ml of AMF, the amount of fluid remaining on the topsheet under 0.1 psi pressure, i.e., rewet, was measured. All tests were conducted in a laboratory maintained at 23°C ± 2°C and 50% ± 2% relative humidity.

[0128] Remove the test product from all packaging, taking care not to press or pull on the product while handling. Do not attempt to smooth out wrinkles. Condition the test product at 23°C ± 2°C and 50% ± 2% relative humidity for at least 2 hours prior to testing.

[0129] Place the test product on a flat, level surface with the body side facing up and load the strikethrough plate in the center of the test product to apply 0.25 psi of pressure on the test product.

[0130] See also Figures 9A to 9E The strike-through plate 9001 is constructed of Plexiglas with overall dimensions of 10.2 cm long by 10.2 cm wide by 3.2 cm high. A longitudinal channel 9007, running along the length of the plate, is 13 mm deep and 28 mm wide at the top plane of the plate, with sidewalls sloping down at 65° to a 15 mm wide base. A central test fluid well 9009 is 26 mm long, 24 mm deep, and 38 mm wide at the top plane of the plate, with sidewalls sloping down at 65° to a 15 mm wide base. At the bottom of test fluid well 9009, an "H"-shaped test fluid reservoir 9003 opens to the bottom of the plate to introduce fluid to the article below. Test fluid reservoir 9003 has an overall length ("L") of 25 mm, a width ("W") of 15 mm, and a depth ("D") of 8 mm. The longitudinal legs of the reservoir are 4 mm wide and have rounded ends with a radius 9010 of 2 mm. The legs are 3.5 mm apart. The center post has a 3 mm radius 9011 and houses opposing electrodes 9004 that are 6 mm apart. The sides of the reservoir are arched outward at a radius 9012 of 14 mm defined by an overall width W of 15 mm. Two wells 9002 (80.5 mm long x 24.5 mm wide x 25 mm deep) located outside the lateral channels are filled with lead shot to adjust the overall mass of the plate to provide 0.25 psi (17.6 gf / cm2) to the test area. 2 ) constraining pressure. Electrodes 9004 are embedded in plate 9001, thereby connecting an external banana-shaped socket 9006 to the inner wall of fluid reservoir 9003. A circuit interval timer is inserted into socket 9006 to the inner wall 9005 of fluid reservoir 9003.

[0131] Use a pipette to carefully dispense 3.0 ml of AMF into the center of the test article through the perforated hole of the strike-through plate within 2 seconds. Once a surge is achieved, remove the plate and start a timer for 3 minutes. After removing the plate, use a color scanner, HPScanjet G4010 or equivalent, to quickly capture an image of the top sheet of the test article, and clean the scanner surface after each scan. In the stain size test described below, the image will be analyzed to measure the stain size on the top sheet. At the end of 3 minutes, 5 pieces of filter paper (typical laboratory filter paper, such as Ahlstrom #632 12.7 cm × 12.7 cm filter paper) that have been pre-weighed (referred to as "dry weight") are placed on top of the approximate center of the area contaminated with fluid. Apply the required mass to generate a pressure of 0.1 psi on the top of the test article and hold it under pressure for 5 seconds. Weigh the filter paper again (referred to as "wet weight"). The difference between the wet weight and dry weight of the filter paper is the light pressure back osmosis under the amount of fluid added.

[0132] Repeat the above steps until a total of 9.0 ml of fluid has been dispensed onto the test product.Report the backwet values ​​to the nearest 0.001 gram for the 3.0 ml, 6.0 ml, and 9.0 ml gush levels.

[0133] In a similar manner, a total of three replicates were tested for each test product to be evaluated. The arithmetic mean of the replicates was calculated (to the nearest 0.001 gram) and reported as the backwet.

[0134] 5. Stain size test

[0135] The area of ​​stain visible on the topsheet of the absorbent article due to fluid remaining on the topsheet was measured on the topsheet images of the test products obtained in the above rewet test for gush levels of 3.0 ml, 6.0 ml and 9.0 ml.

[0136] Image analysis was performed using an image analysis program such as Image J software (version 1.52p or higher, National Institute of Health, USA) or equivalent. Images were calibrated with a ruler image to give an image resolution of 7.95 pixels per millimeter.

[0137] Open the topsheet image in Image J. Set the scale based on the image resolution. Crop the image in the center region to create a minimum bounding rectangle around the entire stain area visible on multiple layers. Convert the image type to 8-bit. Apply a Gaussian blur filter to smooth the image using a Gaussian function with a sigma (radius) of 2. Then, convert the filtered 8-bit grayscale image to a binary image using the "minimum" thresholding method to locate the boundary between the stain area on the topsheet (caused by fluid remaining on the topsheet) and the lighter stain area from subsequent layers.

[0138] Obtain the area of ​​the selected stain area on the topsheet and record it as the topsheet stain size to the nearest 0.01 cm 2 Repeat the entire process for three substantially similar parallel articles. Calculate the arithmetic mean of the three individually recorded measurements (accurate to 0.01 cm). 2 ) and record it as the top sheet stain size.

[0139] 6. Collection time test

[0140] The acquisition time of absorbent articles loaded with AMF as described herein was measured using a strike-through plate and an electronic interval timer. The time required for the absorbent article to acquire one dose of AMF was recorded. All testing was conducted in a laboratory maintained at 23°C ± 2°C and 50% ± 2% relative humidity.

[0141] See also Figures 9A to 9EThe strike-through plate 9001 is constructed of Plexiglas with overall dimensions of 10.2 cm long by 10.2 cm wide by 3.2 cm high. A longitudinal channel 9007, running along the length of the plate, is 13 mm deep and 28 mm wide at the top plane of the plate, with sidewalls sloping down at 65° to a 15 mm wide base. A central test fluid well 9009 is 26 mm long, 24 mm deep, and 38 mm wide at the top plane of the plate, with sidewalls sloping down at 65° to a 15 mm wide base. At the bottom of test fluid well 9009, an "H"-shaped test fluid reservoir 9003 opens to the bottom of the plate to introduce fluid to the article below. Test fluid reservoir 9003 has an overall length ("L") of 25 mm, a width ("W") of 15 mm, and a depth ("D") of 8 mm. The longitudinal legs of the reservoir are 4 mm wide and have rounded ends with a radius 9010 of 2 mm. The legs are 3.5 mm apart. The center post has a 3 mm radius 9011 and houses opposing electrodes 9004 that are 6 mm apart. The sides of the reservoir are arched outward at a radius 9012 of 14 mm defined by an overall width W of 15 mm. Two wells 9002 (80.5 mm long x 24.5 mm wide x 25 mm deep) located outside the lateral channels are filled with lead shot to adjust the overall mass of the plate to provide 0.25 psi (17.6 gf / cm2) to the test area. 2 ) constraining pressure. Electrodes 9004 are embedded in plate 9001, connecting an external banana-shaped socket 9006 to the inner wall of fluid reservoir 9003. A circuit interval timer is inserted into socket 9006 to the inner wall 9005 of fluid reservoir 9003. A circuit interval timer (not shown in the figure) is inserted into socket 9006 and monitors the impedance between the two electrodes 9004, measuring the time from the introduction of the AMF into reservoir 9003 until the AMF is discharged from the reservoir. The timer has a resolution of 0.01 seconds.

[0142] Remove the test product from all packaging, taking care not to press or pull on the product while handling. Do not attempt to smooth out wrinkles. Condition the test specimens at 23°C ± 2°C and 50% ± 2% relative humidity for at least 2 hours prior to testing.

[0143] The required mass of the strike-through panel must be calculated for the specific dimensions of the test article so that a confining pressure of 1.72 kPa is applied. Determine the longitudinal midpoint and lateral midpoint of the absorbent core of the article. Measure and record the lateral width of the core to the nearest 0.1 cm. The required mass of the strike-through panel is calculated as the core width multiplied by the strike-through panel length (10.2 cm) multiplied by 17.6 gf / cm 2 , and record the required mass to the nearest 0.1 g. Add lead pellets to the plate to obtain the calculated mass.

[0144] Connect the electronic circuit interval timer to the permeable plate 9001 and reset the timer to zero. Place the test product on a flat, level surface with the body side facing up. Gently place the permeable plate 9001 onto the center of the test product, ensuring that the "H" shaped reservoir 9003 is centered over the test area.

[0145] Using a mechanical pipette, 3.00 mL ± 0.05 mL of AMF was accurately drawn into the test fluid reservoir 9003. Within 3 seconds or less, the fluid was dispensed along the molded lip at the bottom of the reservoir 9003 without splashing. After the fluid had been collected, the collection time was recorded to the nearest 0.01 second. Electrode 9004 was fully cleaned before each test.

[0146] In a similar manner, test a total of three replicates for each test product to be evaluated. Calculate the arithmetic mean of the replicates (to the nearest 0.01 second) and record it as Acquisition Time (seconds).

[0147] Example

[0148] Example 1. Nonwoven fabric preparation

[0149] Various nonwoven substrates having the configurations shown in Table 1 were prepared using a parallel carding machine and heat treatment.

[0150] Substrate 1: An 8 gsm first web was produced by laying 1.5 denier hydrophobic PE / PET bicomponent fibers, constituting the upper layer, on a conveyor belt. A 10 gsm second web was produced by laying 2 denier hydrophilic PE / PP bicomponent fibers, constituting the lower layer, on a conveyor belt. The second web was overlaid on the first web and subjected to a heat treatment at a temperature of 130°C to 140°C. The heat treatment was performed using a heat-ventilation heat treatment apparatus with an air-permeable conveyor belt. During the heat treatment, the overlaid webs were placed on the air-permeable conveyor belt of the heat treatment apparatus with the surface of the first web in contact with the conveyor belt.

[0151] Substrate 2: Substrate 2 was prepared according to the method disclosed for Substrate 1, using 2 denier hydrophobic PE / PET bicomponent fiber for the upper layer and 10 gsm 2 denier hydrophilic PE / PP bicomponent fiber for the lower layer.

[0152] Substrate 3: Substrate 3 was prepared according to the method disclosed for Substrate 1, using 8 gsm 1.5 denier hydrophobic PE / PET bicomponent fiber for the upper layer and 13 gsm 2 denier hydrophilic PE / PP bicomponent fiber for the lower layer.

[0153] Substrate 4: Substrate 4 was prepared according to the method disclosed for Substrate 1, using 11 gsm 1.5 denier hydrophobic PE / PET bicomponent fiber for the upper layer and 13 gsm 2 denier hydrophilic PE / PP bicomponent fiber for the lower layer.

[0154] Substrate 5: By Figure 3 The pattern shown forms holes, and substrate 5 is prepared using substrate 4.

[0155] Substrate 6: By Figure 4 The pattern shown forms holes, and substrate 6 is prepared using substrate 4.

[0156] Substrate 7: Substrate 7 was prepared according to the method disclosed for Substrate 1, using 14 gsm 1.5 denier hydrophobic PE / PET bicomponent fiber for the upper layer and 13 gsm 2 denier hydrophilic PE / PP bicomponent fiber for the lower layer.

[0157] Substrate 8: Substrate 8 was prepared according to the method disclosed for Substrate 1, using 17 gsm 1.5 denier hydrophobic PE / PET bicomponent fiber for the upper layer and 13 gsm 2 denier hydrophilic PE / PP bicomponent fiber for the lower layer.

[0158] Substrate 9: Substrate 9 was prepared according to the method disclosed for Substrate 1, using 21 gsm 1.5 denier hydrophobic PE / PET bicomponent fiber for the upper layer and 13 gsm 2 denier hydrophilic PE / PP bicomponent fiber for the lower layer.

[0159] Substrate 10: A 24 gsm mixture of 60% 1.5 denier hydrophobic PE / PET bicomponent fibers and 40% 1.5 denier hydrophilic PE / PET bicomponent fibers was laid onto a conveyor belt to obtain a fiber web. The fiber web was heat-treated at a temperature of 130°C to 140°C to obtain a nonwoven fabric. The heat treatment was performed using a heat-through heat treatment apparatus with an air-permeable conveyor belt.

[0160] Substrate 11: By Figure 4 The pattern shown forms holes, and substrate 10 is used to prepare substrate 11.

[0161] Substrates 1 to 9 were prepared using the same 2D hydrophilic PE / PP and 1.5D hydrophobic PE / PET. Substrates 10 and 11 were prepared using the same 1.5D hydrophobic PE / PET and 1.5D hydrophilic PE / PET.

[0162] The contact angles on the top and opposing bottom surfaces of Substrates 1, 3, and 9 were measured according to the Contact Angle Test and are shown in Table 1 below.

[0163] Table 1

[0164]

[0165] Table 1 - continued

[0166]

[0167] Example 2. Absorbent Article

[0168] Sanitary Napkins 1 to 10 were prepared as exemplary absorbent articles using a common secondary topsheet, absorbent core, and backsheet, having a topsheet made from the nonwoven substrate of Example 1.

[0169] Each of the sanitary napkins was tested for acquisition speed and rewet at 0.1 psi / g and 0.5 psi / g according to the Acquisition Speed ​​Test and the Rewet Test disclosed herein. The sanitary napkins were tested for stain size and stain redness according to the Stain Size Test disclosed herein. Table 2 below includes the measurement results.

[0170] Table 2

[0171]

[0172] Table 2 - continued

[0173]

[0174] Each of sanitary napkins 1 to 6 exhibited an acquisition time of no more than 45 seconds for the first 3 ml gush on a new pad, and a rewet of no more than 0.5 g (cumulatively up to a 9 ml load). Fast acquisition times and rewet were also exhibited by sanitary napkins 1 and 2 to 6 having small denier fibers (such as 1.5 denier) that provide the desired superior softness and smoothness.

[0175] The dimensions and values ​​disclosed herein should not be understood as being strictly limited to the exact numerical values ​​recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

[0176] Unless expressly excluded or otherwise limited, each document cited herein, including any cross-referenced or related patent or application, is hereby incorporated by reference in its entirety. The citation of any document is not an admission that it is prior art with respect to any of the present inventions disclosed or claimed herein, or that it, by itself or in combination with any one or more of the references, proposes, suggests, or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0177] 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 invention. It is therefore intended that all such changes and modifications within the scope of the invention be encompassed in the appended claims.

Claims

1. A nonwoven substrate having a top surface and an opposing bottom surface, the nonwoven substrate comprising: an upper layer forming the top surface of the nonwoven substrate, the upper layer comprising hydrophobic fibers; and a lower layer forming the bottom surface of the nonwoven substrate, the lower layer comprising hydrophilic fibers, wherein said top surface of said nonwoven substrate has a first contact angle of not less than about 90 degrees as measured according to the Contact Angle Test, wherein said bottom surface of said nonwoven substrate has a second contact angle of less than about 90 degrees as measured according to a Contact Angle Test, wherein the nonwoven fabric has an integral structure, and wherein the upper layer has a thickness of no greater than about 1400 μm as measured according to the Thickness Test.

2. The nonwoven substrate of claim 1, wherein the hydrophobic fibers and the hydrophilic fibers have different linear densities.

3. The nonwoven substrate of claim 1, wherein the hydrophobic fibers and the hydrophilic fibers have the same linear density.

4. The nonwoven substrate of any one of the preceding claims, wherein the upper layer consists essentially of hydrophobic fibers.

5. The nonwoven substrate of claim 4, wherein the hydrophobic fibers have a linear density of no greater than 2.0 denier.

6. The nonwoven substrate of claim 4, wherein the hydrophobic fibers have a linear density of no greater than 1.5 denier.

7. The nonwoven substrate of any one of the preceding claims, wherein the hydrophobic fibers are staple fibers.

8. The nonwoven substrate of any one of the preceding claims, wherein the hydrophilic fibers are staple fibers.

9. The nonwoven substrate of any one of the preceding claims, wherein the lower layer consists essentially of hydrophilic fibers.

10. The nonwoven substrate of any one of the preceding claims, wherein the nonwoven substrate is free of pores.

11. The nonwoven substrate of any of the preceding claims, wherein the nonwoven substrate is free of embossed bond points.

12. The nonwoven substrate of any preceding claim, wherein the nonwoven substrate has a boundary region where the hydrophobic fibers from the upper layer and the hydrophilic fibers from the lower layer coexist, the boundary region having a thickness of at least about 100 μm.

13. The nonwoven substrate according to any one of the preceding claims, wherein the nonwoven is a carded air-through nonwoven.

14. The nonwoven substrate of any of the preceding claims, wherein the difference between the first contact angle and the second angle is at least about 10 degrees.

15. The nonwoven substrate of any of the preceding claims, wherein the nonwoven substrate further comprises a plurality of apertures.

16. An absorbent article comprising a skin-facing surface, a garment-facing surface, a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core disposed between the topsheet and the backsheet, wherein the topsheet comprises a nonwoven substrate according to any one of the preceding claims, the topsheet being arranged in such a way that the top surface of the nonwoven constitutes the skin-facing surface of the absorbent article.

17. The absorbent article of claim 16, further comprising a fluid distribution layer positioned between the topsheet and the absorbent core.

18. The absorbent article of claim 16, wherein the absorbent article is a sanitary napkin.

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