Non-woven fabric sheet and absorbent article

Abstract

A non-woven fabric sheet (3) used in an absorbent article (1), the non-woven fabric sheet (3): having a longitudinal direction, a lateral direction, and a thickness direction that intersect each other; having a plurality of fibers (3f); and having a first region (DH) and a second region (DL) as seen in the thickness direction. The first region (DH) is a linear region extending in the vertical direction, the density of the fibers (3f) in the first region (DH) is higher than that in the second region (DL), and the thickness of the first region (DH) is less than that of the second region (DL). The first region (DH) and the second region (DL) are provided such that, five minutes after 0.5 mL of horse blood is dropped onto the central part of the non-woven fabric sheet (3), the value obtained by dividing the vertical length of a region in which the horse blood has diffused in the first region (DH) by the vertical length of a region in which the horse blood has diffused in the second region (DL) is 1.5 or greater.

Description

Nonwoven fabric sheets and absorbent articles

[0001] The present invention relates to a nonwoven fabric sheet and an absorbent article.

[0002] Conventionally, absorbent articles such as sanitary napkins, disposable diapers, and absorbent pads have been known. For example, Patent Document 1 discloses a sanitary napkin having a topsheet disposed on the skin-contacting side, a backsheet disposed on the non-skin-contacting side, and an absorbent body disposed between the topsheet and the backsheet. The absorbent body in Patent Document 1 is made of pulp fiber or the like.

[0003] Japanese Patent Application Laid-Open No. 2013-176412

[0004] It is desirable for absorbent articles such as sanitary napkins described in Patent Document 1 and the like to have good absorbency and diffusibility so as to prevent leakage of excrement. However, even in absorbent articles with improved absorbency and diffusibility, there is a problem in that the absorbency and diffusibility are difficult for the wearer to recognize.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a nonwoven fabric sheet that improves the absorbency of excrement within the nonwoven fabric sheet while easily giving the impression to the wearer that the nonwoven fabric sheet is an absorbent article with improved excrement diffusion and absorption.

[0006] The primary invention for achieving the above object is a nonwoven fabric sheet for use in absorbent articles, the nonwoven fabric sheet having a plurality of fibers in longitudinal, transverse, and thickness directions that intersect with one another, and having a first region and a second region as viewed in the thickness direction, the first region being a linear region extending in the longitudinal direction, having a higher fiber density than the second region and being thinner than the second region, the first region and the second region being arranged so that, 5 minutes after 0.5 ml of horse blood is dropped onto the center of the nonwoven fabric sheet, the value obtained by dividing the longitudinal length of the horse blood diffusion region in the first region by the longitudinal length of the horse blood diffusion region in the second region is 1.5 or more. Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0007] According to the present invention, it is possible to provide a nonwoven fabric sheet that improves the absorbency of excrement within the nonwoven fabric sheet, while easily giving the impression to the wearer that the nonwoven fabric sheet is an absorbent article with improved diffusion and absorption of excrement.

[0008] 7 is a plan view of the sanitary napkin 1 as seen from the skin side. FIG. 5 is a schematic cross-sectional view taken along the arrows A-A in FIG. 1. FIG. 6 is a diagram illustrating the configuration of the napkin 1. FIG. 7 is a diagram illustrating the absorbent layer 10 of the napkin 1. FIG. 5A is a diagram illustrating a cross-section of the skin side layer 2. FIG. 5B is a diagram illustrating a cross-section of the non-skin side layer 3. FIG. 6 is a diagram illustrating the horse blood diffusion region K1 in the high density section DH and the horse blood diffusion region K2 in the low density section DL. FIG. 7 is an enlarged view of part X in FIG. 4. FIG. 7 is a schematic cross-sectional view taken along the arrows B-B in FIG. 7. FIG. 7 is a diagram illustrating a water retention test. FIG. 7 is a diagram illustrating the rolling up of the fibers 3f. FIG. 7 shows the measurement results of each example and comparative example.

[0009] The present specification and the accompanying drawings make at least the following clear: (Aspect 1) A nonwoven fabric sheet for use in absorbent articles, the nonwoven fabric sheet having a longitudinal direction, a transverse direction, and a thickness direction that intersect with one another, comprising a plurality of fibers, and having a first region and a second region when viewed in the thickness direction, the first region being a linear region extending in the longitudinal direction, having a higher fiber density than the second region and being thinner than the second region, the first region and the second region being arranged so that, 5 minutes after 0.5 ml of horse blood is dropped onto the center of the nonwoven fabric sheet, the value obtained by dividing the longitudinal length of the horse blood diffusion region in the first region by the longitudinal length of the horse blood diffusion region in the second region is 1.5 or more.

[0010] According to the nonwoven fabric sheet of aspect 1, the first and second regions are provided such that the value obtained by dividing the vertical length of the horse blood diffusion area in the first region by the vertical length of the horse blood diffusion area in the second region is 1.5 or more. This makes it easier to promote vertical diffusion of excrement in the first region than in the second region of the nonwoven fabric sheet when an absorbent article using the nonwoven fabric sheet is worn, compared to when the first and second regions are provided such that the value obtained by dividing the vertical length of the horse blood diffusion area in the first region by the vertical length of the horse blood diffusion area in the second region is less than 1.5.This improves the absorbency of excrement within the nonwoven fabric sheet, while also giving the impression to the wearer that the absorbent article has improved diffusion and absorption of excrement.

[0011] (Aspect 2) The nonwoven fabric sheet of aspect 1, wherein the plurality of fibers are not fused to one another.

[0012] Generally, fused fibers tend to hinder the diffusion of liquid and reduce the liquid absorbency and liquid retention. In the nonwoven fabric sheet of Aspect 2, the plurality of fibers are not fused, which reduces the risk of hindering the diffusion of liquid and reducing the liquid absorbency and liquid retention compared to when the fibers are fused.

[0013] (Aspect 3) The nonwoven fabric sheet of aspect 1 or 2, wherein the plurality of fibers include latent crimp fibers.

[0014] According to the nonwoven fabric sheet of aspect 3, the plurality of fibers have latent crimped fibers, which reduces the risk of the latent crimped fibers absorbing liquid and swelling like pulp fibers. This makes it easier to maintain voids between the fibers, which makes it easier to improve liquid absorbency.

[0015] (Aspect 4) The nonwoven fabric sheet of aspect 3, wherein the latently crimped fibers are conjugated fibers in which polyethylene terephthalate and modified polyethylene terephthalate are bonded side-by-side.

[0016] According to the nonwoven fabric sheet of aspect 4, the crimping of the latently crimped fibers tends to narrow the gaps between the fibers, which makes it easier to diffuse absorbed liquid within the nonwoven fabric sheet by capillary action.

[0017] (Aspect 5) The nonwoven fabric sheet of any one of Aspects 1 to 4, wherein the value obtained by dividing the average distance between fibers in the second regions by the average distance between fibers in the first regions is 3.0 or greater.

[0018] With the nonwoven fabric sheet of aspect 5, the diffusion of excretory liquid in the first region is more easily promoted by capillary action than when the value obtained by dividing the average distance between fibers in the second region by the average distance between fibers in the first region is less than 3.0, thereby improving the absorbency of excretory liquid within the nonwoven fabric sheet and more easily giving the impression to the wearer and others that the article has improved diffusion and absorption of excretory liquid.

[0019] (Aspect 6) The nonwoven fabric sheet of any one of Aspects 1 to 5, wherein the nonwoven fabric sheet is an absorbent that absorbs liquid.

[0020] According to the nonwoven fabric sheet of aspect 6, it is easier to promote the vertical diffusion of absorbed liquid within the nonwoven fabric sheet, thereby improving the absorbency of excreted liquid in the absorbent article and giving the impression to the wearer and others that the absorbent article has improved diffusion and absorption of excreted liquid.

[0021] (Aspect 7) The nonwoven fabric sheet of any one of Aspects 1 to 6, wherein the length in the longitudinal direction of the nonwoven fabric sheet is longer than the length in the transverse direction, and the second region is adjacent to each of the first region on both sides in the longitudinal direction.

[0022] According to the nonwoven fabric sheet of aspect 7, liquid absorbed in the second region located on one side in the longitudinal direction can be easily transferred to the first region by capillary action, and any liquid that has been absorbed in the first region but cannot be completely absorbed is absorbed in the second region located on the other side in the longitudinal direction, which makes it easier to promote the diffusion of liquid in the longitudinal direction of the nonwoven fabric sheet.

[0023] (Aspect 8) The nonwoven fabric sheet of any one of Aspects 1 to 7, wherein the length of the nonwoven fabric sheet in the longitudinal direction is longer than the length of the nonwoven fabric sheet in the transverse direction, the first region has a portion that is inclined with respect to the longitudinal direction, and the smaller angle between the longitudinal direction and the first region is 45 degrees or less.

[0024] According to the nonwoven fabric sheet of aspect 8, the liquid absorbed in the longitudinal direction of the nonwoven fabric sheet can be easily diffused.

[0025] (Aspect 9) The nonwoven fabric sheet of any one of Aspects 1 to 8, wherein the length of the nonwoven fabric sheet in the longitudinal direction is longer than the length of the nonwoven fabric sheet in the transverse direction, a plurality of the first regions are provided, and the plurality of first regions are spaced apart from each other in the transverse direction.

[0026] According to the nonwoven fabric sheet of aspect 9, the risk of excreted liquid continuing to accumulate in the areas where the first regions overlap in the horizontal direction is reduced, making it easier to diffuse the liquid absorbed in the vertical direction of the nonwoven fabric sheet.

[0027] (Aspect 10) The nonwoven fabric sheet of any one of Aspects 1 to 9, wherein the length in the longitudinal direction of the nonwoven fabric sheet is longer than the length in the transverse direction, and when the length in the longitudinal direction of the nonwoven fabric sheet is divided into thirds and the central portion in the longitudinal direction is defined as a central portion, the first region has a portion that is continuous from the upper end to the lower end of at least the central portion.

[0028] According to the nonwoven fabric sheet of aspect 10, the diffusion of liquid in the vertical direction is easily promoted at least in the central portion.

[0029] (Embodiment 11) The nonwoven fabric sheet of any one of embodiments 1 to 10, wherein the average distance between the fibers is 11 to 28 μm.

[0030] According to the nonwoven fabric sheet of aspect 11, more flow paths for diffusing liquid and areas for retaining liquid are secured than when the average interfiber distance is less than 11 μm, while the nonwoven fabric sheet is more likely to promote the drawing in and absorption of absorbed liquid by capillary action than when the average interfiber distance is greater than 28 μm.

[0031] (Aspect 12) The nonwoven fabric sheet of any one of Aspects 1 to 11, wherein the first region has a recess with a bottom.

[0032] According to the nonwoven fabric sheet of aspect 12, by having a bottomed recess, when an absorbent article using the nonwoven fabric sheet is worn, it becomes easier to move the excrement absorbed from the skin side to the non-skin side, which makes it easier to reduce discomfort when wearing the absorbent article.

[0033] (Aspect 13) The nonwoven fabric sheet of any one of Aspects 1 to 12, wherein the fiber basis weight of the nonwoven fabric sheet is 80 gsm or more and 140 gsm or less.

[0034] According to the nonwoven fabric sheet of aspect 13, the nonwoven fabric sheet is more likely to absorb liquid than when the fiber basis weight of the nonwoven fabric sheet is less than 80 gsm, and the risk of the nonwoven fabric sheet becoming excessively thick or stiff can be reduced compared to when the fiber basis weight of the nonwoven fabric sheet is more than 140 gsm.

[0035] (Aspect 14) The nonwoven fabric sheet of any one of Aspects 1 to 13, wherein the nonwoven fabric sheet is provided in the crotch area of ​​a wearer when the absorbent article is worn.

[0036] According to the nonwoven fabric sheet of aspect 14, when the nonwoven fabric sheet absorbs excreted liquid, the excreted liquid is more easily dispersed within the nonwoven fabric sheet, thereby reducing discomfort caused by excreted liquid leaking or being retained in a localized area.

[0037] (Aspect 15) The nonwoven fabric sheet of any one of Aspects 1 to 14, wherein when a pre-absorption weight is a weight of the nonwoven fabric sheet before absorbing a liquid, a post-absorption weight is a weight of the nonwoven fabric sheet after immersing the nonwoven fabric sheet in distilled water for 60 seconds and then removing it from the distilled water and hanging it for 90 seconds, and the post-absorption weight is a weight of distilled water retained by the nonwoven fabric sheet, the value obtained by subtracting the post-absorption weight from the pre-absorption weight is defined as the retained weight of the nonwoven fabric sheet, and the value obtained by dividing the retained weight by the pre-absorption weight is 8 or more.

[0038] According to the nonwoven fabric sheet of aspect 15, the absorbent article can retain more excrement than when the weight of distilled water retained by the nonwoven fabric sheet divided by the weight before absorption is set to less than 8, thereby reducing the risk of excrement leaking from an absorbent article using the nonwoven fabric sheet.

[0039] (Aspect 16) The nonwoven fabric sheet of aspect 3, wherein the nonwoven fabric sheet has at least one latently crimped fiber whose winding direction is inclined at an angle θ of more than 55 degrees relative to the axial direction.

[0040] According to aspect 16, even if there is at least one latent crimped fiber whose winding direction is inclined at an angle θ of more than 55 degrees relative to the axial direction, the absorbency of excreted liquid within the nonwoven fabric sheet is improved, and the wearer or the like is more likely to be impressed by the absorbent article having improved diffusion and absorption of excreted liquid.

[0041] (Aspect 17) The absorbent article of any one of Aspects 1 to 15, further comprising a liquid-impermeable non-skin-side sheet provided on the non-skin side of the nonwoven fabric sheet, the nonwoven fabric sheet having a portion in contact with the non-skin-side sheet.

[0042] According to the absorbent article of aspect 17, the diffusion state of the excrement absorbed by the nonwoven fabric sheet can be easily seen from the non-skin side of the absorbent article, making it easier for the wearer to recognize that the absorbent article is equipped with a nonwoven fabric sheet with improved diffusion properties.

[0043] == ...

[0044] <<<Configuration of Sanitary Napkin 1>>> Fig. 1 is a plan view of a sanitary napkin 1 (hereinafter also referred to as "napkin") as seen from the skin side. Fig. 2 is a schematic cross-sectional view of the napkin 1 taken along the arrows A-A. Fig. 3 is a diagram illustrating the configuration of the napkin 1. The napkin 1 has a longitudinal direction, a width direction, and a thickness direction, which are perpendicular to one another. In the thickness direction, the side that contacts the wearer's skin is the skin side, and the opposite side is the non-skin side. The skin side in the thickness direction is the side that receives excrement (liquid) when worn. Furthermore, the longitudinal direction of the napkin 1 is aligned with the vertical direction of the non-skin side layer 3, which will be described later, and the width direction of the napkin 1 is aligned with the horizontal direction of the non-skin side layer 3. The center line C-C shown in Fig. 1 etc. indicates the center (central position) of the napkin 1 in the width direction.

[0045] The napkin 1 has a skin-side layer (nonwoven fabric sheet) 2, a non-skin-side layer (nonwoven fabric sheet) 3, a back sheet 4, and a side sheet 5. As shown in Fig. 3 etc., the napkin 1 is stacked in the thickness direction in the following order from the skin side: side sheet 5, skin-side layer 2, non-skin-side layer 3, and back sheet 4. The components stacked in the thickness direction are appropriately fixed together with an adhesive such as a hot melt adhesive.

[0046] The skin-side layer 2 is the skin-side sheet located closest to the skin in the widthwise center of the napkin 1, and is an absorbent member that contacts the excretory opening and receives excrement discharged from the excretory opening when the napkin 1 is worn. The skin-side layer 2 is substantially rectangular in shape, with its longitudinal length L2 being longer than its width length W2. By providing the skin-side layer 2 at the wearer's crotch when the napkin 1 is worn, when the napkin 1 absorbs excrement, the skin-side layer 2 can absorb the excrement and diffuse the absorbed excrement toward the non-skin-side layer 3. This reduces discomfort to the wearer caused by excrement leaking from the napkin 1 or excrement remaining locally on the surface of the skin-side layer 2, for example.

[0047] The non-skinside layer 3 is a nonwoven fabric sheet provided between the skinside layer 2 and the backsheet 4 in the thickness direction. The non-skinside layer 3 is slightly smaller than the skinside layer 2 in a plan view. The non-skinside layer 3 has a generally rectangular shape that is long in the longitudinal direction, with the longitudinal length L3 being longer than the widthwise length W3. The non-skinside layer 3 is an absorbent member that absorbs excrement migrated (diffused) from the skinside layer 2 and retains the excrement. By providing the non-skinside layer 3 in the crotch area of ​​the wearer when the napkin 1 is worn, when the napkin 1 absorbs excrement, the non-skinside layer 3 can absorb the excrement and diffuse it within the non-skinside layer 3. This reduces discomfort to the wearer caused by excrement leaking from the napkin 1 or excrement remaining locally on the surface of the skinside layer 2, for example.

[0048] The skin-side layer 2 and the non-skin-side layer 3 are nonwoven fabrics (nonwoven fabric sheets) composed of latently crimped fibers 2f and latently crimped fibers 3f (see FIG. 5 ), respectively. In this embodiment, the skin-side layer 2 and the non-skin-side layer 3 are nonwoven fabric sheets formed solely of latently crimped fibers (100% latently crimped fibers). However, the layers (nonwoven fabrics) constituting the skin-side layer 2 and the non-skin-side layer 3 may contain, in addition to latently crimped fibers, fibers made of polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters (PET and PBT), polyamides, etc., composite fibers thereof, as well as hydrophilic fibers such as rayon, pulp, and cotton. Hereinafter, the latently crimped fibers 2f and 3f will also be simply referred to as "fibers 2f" and "fibers 3f."

[0049] A "nonwoven fabric" is a fibrous sheet, web, or batt in which fibers are oriented unidirectionally or randomly and bonded by entanglement, fusion, and / or adhesion (JIS L0222:2001, Nonwoven Fabrics, Terminology 101). In other words, a nonwoven fabric is a sheet in which fibers are integrated without being woven, with a breaking strength of 5 [N] / 25 mm or greater. Breaking strength can be measured using well-known methods, such as the following: A tensile tester (Shimadzu Corporation: Autograph, AGS-1kNG) equipped with a load cell with a maximum load capacity of 50 N is used. To measure the separation strength of a nonwoven fabric sheet, one chuck grips the leading edge of one side of the nonwoven fabric sheet in the longitudinal or transverse direction, and the other chuck grips the other side of the nonwoven fabric sheet. The load applied to the two chucks is measured while pulling the two chucks at a constant speed (e.g., 100 mm / min) so that the distance between the two chucks increases using a tensile tester. The load at which the nonwoven fabric sheet breaks is taken as the breaking strength.

[0050] Examples of nonwoven fabrics include nonwoven fabrics obtained by a meltblown method (meltblown nonwoven fabric), nonwoven fabrics obtained by an electrospinning method (electrospun nonwoven fabric), nonwoven fabrics obtained by a spunbonding method (spunbond nonwoven fabric), nonwoven fabrics produced by an air-through method (air-through nonwoven fabric), nonwoven fabrics produced by a spunlace method (spunlace nonwoven fabric), nonwoven fabrics produced by a needlepunch method (needlepunch nonwoven fabric), laminates of two or more of these nonwoven fabrics, or laminates of these nonwoven fabrics with other nonwoven fabrics or other materials. The skin side layer 2 and the non-skin side layer 3 of this embodiment are each a spunlace nonwoven fabric in which no adhesive is used and the fibers are entangled by a water flow.

[0051] The nonwoven fabric sheet for the skin-side layer 2 of the napkin 1 of this embodiment is formed using the following spunlace method. (a) First, hydrophilic fibers 2fb are processed using a carding machine or the like to form a non-skin-side fiber web in the form of a carded web or the like. (b) Next, hydrophobic fibers 2fa are processed using a carding machine or the like to form a skin-side fiber web in the form of a carded web or the like. This is then fed onto the non-skin-side fiber web while the non-skin-side fiber web is being conveyed, and the two are laminated to obtain a laminated web. (c) A high-pressure water jet or other water jet treatment is applied from the skin side of the laminated web to entangle the fibers between each fiber layer and the fibers within each web, thereby obtaining a laminate. (d) Finally, the laminate is placed in a dryer and heated to a temperature at which the potentially crimpable fibers can crimp, thereby obtaining an integrated nonwoven fabric sheet (skin-side layer 2). This nonwoven fabric sheet has voids formed by the plurality of fibers 2f.

[0052] The nonwoven fabric sheet of the non-skinside layer 3 of the napkin 1 of this embodiment is formed in the same manner as the nonwoven fabric sheet of the skinside layer 2. However, the nonwoven fabric sheet of the non-skinside layer 3 differs from the skinside layer 2 in that it does not use hydrophobic fibers and is made by laminating only a web of hydrophilic fibers.

[0053] Potentially crimped fibers 2f and 3f are fibers that crimp upon heat treatment to develop a helical shape. Potentially crimped fibers are fibers that, when viewed in the thickness direction (cross section), are coiled (a shape that is wound 360 degrees, such as a circle or ellipse). Potentially crimpable fibers 2f and 3f can be, for example, side-by-side composite fibers in which high-shrinkage and low-shrinkage components are arranged in parallel, or eccentric core-sheath composite fibers in which the high-shrinkage component is the core and the low-shrinkage component is the sheath, with the centers of gravity of the two components not overlapping at a single point. When the crimp of the latently crimpable fiber is developed, the latently crimpable fiber crimps into a coiled shape.

[0054] The resins having different thermal shrinkage rates or thermal expansion coefficients that form the latent crimped fibers 2f, 3f can be any combination of resins with different thermal shrinkage rates or thermal expansion coefficients, and may be a combination of the same or a single resin, or a combination of different resins. Specific examples of combinations of resins with different thermal shrinkage rates or thermal expansion coefficients that form the latent crimped fibers include a combination of polyester resins or a combination of polyamide resins.

[0055] The nonwoven fabrics of the skin side layer 2 and the non-skin side layer 3 of this embodiment each use a combination of polyester-based resins (single-component resins), specifically, a latent crimp fiber of a combination of polyethylene terephthalate (PET) and modified PET (modified polyethylene terephthalate). Modified PET is PET modified by copolymerizing the PET components ethylene glycol and terephthalic acid with a minor amount of a diol component other than ethylene glycol or a dicarboxylic acid component other than terephthalic acid. Specific examples of diol components other than ethylene glycol include 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyethylene glycol, and polytetramethylene glycol. Specific examples of dicarboxylic acid components other than terephthalic acid include isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, and sebacic acid. A web composed of latently crimpable fibers of a combination of PET and modified PET is formed using a web-forming means such as a carding machine, and the fibers in this web are entangled by a spunlace method to form a nonwoven fabric. This is then heated to a predetermined temperature to induce crimping of the latently crimpable fibers, thereby producing the nonwoven fabrics of the skin side layer 2 and the non-skin side layer 3. Due to this crimping of the fibers, the basis weight of the latently crimped fibers in the nonwoven fabric after heating is greater than the basis weight of the latently crimpable fibers in the nonwoven fabric before heating. In other words, the crimping of the latently crimpable fibers causes the nonwoven fabric to shrink, increasing the basis weight of the fibers.

[0056] The skin-side layer 2 and the non-skin-side layer 3 are each an absorbent layer 10 having a predetermined thickness and being liquid-permeable and capable of absorbing and retaining liquid. Fig. 4 is a diagram illustrating the absorbent layer 10 of the napkin 1. In the napkin 1, the skin-side layer 2 is a skin-side sheet that contacts the wearer's skin and is a member that first receives excrement when worn, absorbs the received excrement within the skin-side layer 2, and then allows it to permeate toward the non-skin side. The non-skin-side layer 3 is a member that absorbs and retains excrement that has permeated from the skin-side layer 2.

[0057] As shown in Figure 5, the skinside layer 2 and the non-skinside layer 3 each have voids formed by a plurality of fibers (latently crimped fibers) 2f, 3f. Figure 5A is a schematic diagram showing the cross section of the skinside layer 2, and Figure 5B is a schematic diagram showing the cross section of the non-skinside layer 3. The dimensions in Figures 5A and 5B are not necessarily accurate. The voids in the skinside layer 2 and the non-skinside layer 3 may be voids between discontinuous fibers (a plurality of fibers), voids formed by a single continuous fiber that is curved or spiral, or a combination of these. The voids formed by a plurality of fibers 2f, 3f refer to spaces or regions in the skinside layer 2 and the non-skinside layer 3 where a plurality of fibers 2f, 3f are not present. The voids may not only be spaces surrounded by the fibers 2f, 3f or spaces closed by the fibers, but also at least partially open spaces formed by the fibers 2f, 3f.

[0058] The skin-side layer 2 and the non-skin-side layer 3 each contain latently crimped fibers 2f and 3f, and the crimping of the fibers 2f and 3f causes the fibers 2f and 3f to form a spiral shape that intertwines and threads between the fibers 2f and 3f. For example, the distance between the fibers 2f and 3f and the fibers 2f and 3f may be shortened by the crimping, or other fibers may be inserted between the shortened fibers 2f and 3f and the fibers 2f and 3f, further reducing the gaps between the fibers 2f and 3f and the fibers 2f and 3f. Therefore, the gaps formed by the fibers 2f and 3f containing latently crimped fibers are smaller than the gaps formed by multiple fibers in a typical nonwoven fabric made of uncrimped fibers.

[0059] Furthermore, the latently crimped fibers 2f, 3f provided in the skinside layer 2 and the non-skinside layer 3, respectively, are resistant to liquid absorption by themselves. For example, fibers such as pulp fibers absorb liquid (excrement) and increase in diameter, but the latently crimped fibers 2f, 3f in the skinside layer 2 and the non-skinside layer 3 are resistant to liquid absorption within the fibers even when they come into contact with liquid. Therefore, in the skinside layer 2 and the non-skinside layer 3, even when the napkin 1 absorbs excrement while being worn, the latently crimped fibers 2f, 3f in the skinside layer 2 and the non-skinside layer 3 are resistant to increasing in diameter. Because the fibers are resistant to increasing in diameter, the size of the voids formed by the fibers 2f, 3f is resistant to becoming smaller, and the voids are resistant to collapse. As a result, the skin-side layer 2 and the non-skin-side layer 3 can retain liquid (excrement) in the voids formed by the fibers 2f, 3f, making the skin-side layer 2 and the non-skin-side layer 3 layers permeable to liquid as well as capable of absorbing and retaining liquid. Furthermore, the skin-side layer 2 and the non-skin-side layer 3 are nonwoven fabric sheets formed from the fibers 2f, 3f, respectively, and have voids formed by the fibers 2f, 3f, so they are also highly breathable, reducing stuffiness and rough skin that the wearer may experience when wearing the garment and improving comfort when worn.

[0060] As described above, the latently crimped fibers 2f in the skin-side layer 2 are latently crimpable fibers made from a combination of PET and modified PET, and the fibers are of the same thickness throughout. In this embodiment, the latently crimped fibers 2fa have a thickness of 2.2 dtex. The basis weight of the skin-side layer 2 is approximately 170 gsm. It is also preferable to use hydrophobic fibers on the skin-side side of the skin-side layer 2 and hydrophilic fibers on the non-skin-side side.

[0061] The basis weight of the non-skinside layer 3 in this embodiment is approximately 140 gsm. The basis weight of the fibers 3f of the non-skinside layer 3 is preferably 80 gsm or more and 140 gsm or less. This allows more voids to be formed in the non-skinside layer 3 than when the basis weight of the fibers 3f of the non-skinside layer 3 is less than 80 gsm, making the non-skinside layer 3 more likely to absorb liquid. On the other hand, this reduces the risk of the non-skinside layer 3 becoming excessively thick or stiff compared to when the basis weight of the fibers 3f of the non-skinside layer 3 is greater than 140 gsm.

[0062] The latently crimped fibers 3f in the non-skin side layer 3 are latently crimpable fibers made of a combination of PET and modified PET, and have the same diameter throughout the thickness direction. In this embodiment, the diameter of the latently crimped fibers 3f in the non-skin side layer 3 is 2.2 dtex.

[0063] The back sheet 4 is a liquid-impermeable sheet (non-skin-side sheet) disposed on the non-skin-side side of the non-skin-side layer 3. An example of the liquid-impermeable sheet is a polyethylene (PE) resin film. The side sheets 5 are sheets extending outward from both widthwise edges of the skin-side surface of the skin-side layer 2. Examples of the side sheets 5 include a hydrophobic air-through nonwoven fabric and a hydrophobic spunbond nonwoven fabric.

[0064] The napkin 1 also has a pair of wing portions 1w extending outward in the width direction at approximately the center in the longitudinal direction. The wing portions 1w are formed by the side sheets 5 and the back sheet 4. The napkin 1 does not necessarily have to have the wing portions 1w. When the napkin 1 does not have the wing portions 1w, it may or may not have the side sheets 5.

[0065] The napkin 1 also has compressed portions 20 in which the skin side layer 2 and the non-skin side layer 3 are recessed in the thickness direction. The compressed portions 20 fix the positions of the skin side layer 2 and the non-skin side layer 3 and improve the liquid diffusibility of the napkin 1.

[0066] In the compressed portion 20, the thickness of the napkin 1 is thinner than in the surrounding area, and the fiber density of the napkin 1 (skinside layer 2 and non-skinside layer 3) is higher. These comparisons can be made by well-known methods. The thickness of the napkin 1 can be compared by visual comparison, or by using a dial thickness gauge ID-C1012C manufactured by Mitutoyo Corporation or an equivalent instrument to measure the thickness of the target area at a pressure of, for example, 3.0 gf / cm. ２ An example of a method for comparing the density of napkins 1 is to obtain and compare values ​​measured by applying pressure at a pressure of 1000 kJ / cm2 and measuring the density. An example of a method for comparing the density of napkins 1 is to compare images of a cross section of napkin 1 cut in the thickness direction, enlarged using an electron microscope or the like. The shape of compressed portions 20 is not limited to that shown in Fig. 1. For example, a plurality of discretely arranged point-like compressed portions may also be used.

[0067] <<<Regarding the Non-Skinside Layer 3>>> The non-skinside layer 3 is a nonwoven fabric sheet used in the napkin 1 (absorbent article). The non-skinside layer 3 has a longitudinal direction, a transverse direction, and a thickness direction that intersect with one another, with the longitudinal direction of the non-skinside layer 3 running along the longitudinal direction of the napkin 1, the transverse direction of the non-skinside layer 3 running along the width direction of the napkin 1, and the thickness direction of the non-skinside layer 3 running along the thickness direction of the napkin 1. Hereinafter, the longitudinal direction of the non-skinside layer 3 will also be referred to as the "longitudinal direction," and the transverse direction of the non-skinside layer 3 will also be referred to as the "width direction."

[0068] The non-skin side layer 3 is a nonwoven fabric sheet in which fibers are integrated without being woven into a sheet. In this embodiment, a plurality of fibers 3f are entangled in a predetermined manner to form a sheet.

[0069] The absorbent body (absorbent core) of a typical absorbent article is formed from liquid-absorbent fibers such as pulp fibers, SAP, polymer foam structures, etc. For example, an absorbent body (absorbent core) formed from liquid-absorbent fibers such as pulp fibers is simply a laminate of liquid-absorbent fibers, and the fibers are not intertwined with each other. As a result, voids formed by multiple fibers are difficult to maintain their shape. When liquid is absorbed, not only do the liquid-absorbent fibers themselves become thicker, but the voids also easily lose their shape, making it difficult for the voids to absorb liquid. Furthermore, because the liquid-absorbent fibers themselves absorb liquid, the voids are easily crushed. Furthermore, absorbent cores formed from liquid-absorbent fibers such as pulp fibers have a breaking strength of less than 5 [N] / 25 mm, making them more susceptible to deformation and breakage than nonwoven fabric sheets (non-skin-side layer 3). As such, absorbent bodies formed from liquid-absorbent fibers tend to lose their shape when absorbing liquid, which makes the absorbent body prone to twisting and a decrease in strength.

[0070] In contrast, the non-skinside layer 3 made of a nonwoven fabric sheet is a nonwoven fabric whose shape is maintained by the entanglement of multiple fibers, and therefore the shape of the voids formed by the multiple fibers is easily maintained. Therefore, when the non-skinside layer 3 is used as an absorbent body of a napkin 1, the voids are easily able to retain liquid. Furthermore, by maintaining the shape of the voids through entanglement, even when liquid is absorbed, distortion of the shape of the non-skinside layer 3 (absorbent body) can be reduced, making it easier for the shape of the non-skinside layer 3 to be maintained. Therefore, even when the napkin 1 is worn for a long period of time or when bodily excrement is absorbed multiple times, deformation of the napkin 1 (non-skinside layer 3) can be reduced. Furthermore, because the napkin 1 has voids formed by the fibers 3f, it has better breathability than the absorbent bodies of typical absorbent articles.

[0071] The non-skinside layer 3 is used in the napkin 1 as an absorbent that absorbs liquid. Generally, absorbents in absorbent articles such as the napkin 1 can absorb more excreted liquid by diffusing the absorbed excreted liquid over a wide area within the absorbent rather than absorbing it only in a single area when the absorbent article is worn, thereby improving the absorbency of excreted liquid and reducing the risk of excreted liquid remaining on the skin-side surface of the absorbent article and causing discomfort to the wearer's skin. While improved diffusion in the non-skinside layer 3 is preferable, due to the shape of the human body, the width of the napkin 1 and the non-skinside layer 3 is shorter than the length in the longitudinal direction, so it is preferable for the absorbent in absorbent articles such as the napkin 1 to promote diffusion in the longitudinal direction. Furthermore, it is more preferable for the wearer to be able to recognize the improved absorbency and diffusion of excreted liquid in an absorbent article such as the napkin 1.

[0072] Therefore, the non-skinside layer 3 of the napkin 1 has a high-density region (first region) DH and a low-density region (second region) DL that have the following characteristics, so that 5 minutes after 0.5 mL of horse blood is dropped onto the center of the non-skinside layer 3 (nonwoven fabric sheet), the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density region DH divided by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density region DL is 1.5 or more (LK1 / LK2≧1.5). This improves the absorbency and diffusibility of excrement in the napkin 1 while making it easier for the wearer to recognize that the absorbency and diffusibility have been improved.

[0073] The longitudinal length LK1 of the diffusion region K1 and the longitudinal length LK2 of the diffusion region K2 are obtained by the following horse blood drop test. Figure 6 is a diagram illustrating the horse blood diffusion region K1 in the high density part DH and the horse blood diffusion region K2 in the low density part DL.

[0074] <Horse Blood Dropping Test> First, the non-skinside layer 3 (nonwoven fabric sheet) is placed on a horizontal surface as a sample. When the non-skinside layer 3 is used in a napkin 1, as in this embodiment, the non-skinside layer 3 is removed from the napkin 1, and a sample of a predetermined size is cut from the removed non-skinside layer 3 and placed on a horizontal surface. In this embodiment, the non-skinside layer 3 removed from the napkin 1 is cut into a rectangular shape measuring 120 mm in length and 35 mm in width, and this is used as the sample. Note that the sample onto which horse blood is dropped may have the same shape and size as the non-skinside layer 3 used in absorbent articles such as the napkin 1, or may be cut to any size. In this embodiment, the sample to be measured is the non-skinside layer 3 removed from the napkin 1 and cut into a rectangular shape measuring 120 mm in length and 35 mm in width.

[0075] Next, 0.5 ml of horse blood was dripped onto the center of the sample using a pipetter. Specifically, horse blood warmed to 38°C was dripped onto the center of the sample from a position 5 mm perpendicular to the sample surface toward the center. The horse blood used in this embodiment was "Horse Defibered Blood (Made in Japan) 100 ml" (product number: 003-574, manufactured by Japan Bioserum Co., Ltd.). If the dripped horse blood reaches the vertical or horizontal edge of the sample, the diffusion area K may not be measured correctly. On the other hand, if too little horse blood is dripped, the diffusion area K may vary, potentially resulting in inaccurate measurement results. Therefore, dripping 0.5 ml of horse blood onto the sample makes it easier to accurately measure the diffusion area K and the longitudinal lengths LK1 and LK2 of the diffusion area K than if the amount of horse blood were more or less than 0.5 ml.

[0076] Then, five minutes after the drop, the lengths of the diffusion regions K of the horse blood are measured. To measure the diffusion region K, the longitudinal length LK1 of the diffusion region K1 in the high-density section DH and the longitudinal length LK2 of the diffusion region K2 in the low-density section DL are measured. Because the high-density section DH is thinner than the low-density section DL, the longitudinal length LK1 of the thinner section is measured as the diffusion region K1 in the high-density section DH, and the longitudinal length LK2 of the thicker section is measured as the diffusion region K2 in the low-density section DL. Here, the longitudinal lengths LK1 and LK2 refer to the lengths from the front-most end to the rear-most end of each diffusion region K1 and K2 in the longitudinal direction.

[0077] The measurement results of the diffusion area for horse blood in this horse blood drop test can be assumed to show a diffusion state similar to that of the diffusion area for human excrement (for example, menstrual blood).

[0078] As described above, the non-skinside layer 3 has a plurality of fibers 3f in the high-density portion DH and the low-density portion DL. As shown in Figures 4 and 7, the high-density portion DH is a linear region extending in the longitudinal direction. Figure 7 is an enlarged view of portion X in Figure 4. The high-density portion DH has a higher density of fibers 3f than the surrounding area (low-density portion DL).

[0079] The "linear" high-density portion DH is not limited to a linearly continuous portion where portions with a higher density than the surrounding area are arranged. When multiple high-density portions are arranged intermittently in a line or dots, the linear high-density portion DH also includes the area between the multiple adjacent high-density portions. The area between the multiple adjacent high-density portions that are close to each other has a lower fiber density than the portion formed as a high-density portion, but is an area with a higher fiber density than the surrounding area, so the entire area becomes a linear high-density portion.

[0080] The high-density portion DH is thinner than the surrounding area (the low-density portion DL). As shown in FIG. 8 , in the napkin 1 of this embodiment, the thickness of the low-density portion DL is the thickness H3 of the non-skinside layer 3, and the thickness Hdh of the high-density portion DH is shorter than the thickness H3 of the low-density portion DL (Hdh<H3). FIG. 8 is a schematic cross-sectional view taken along the arrows B-B in FIG. 7 . The thicknesses of the high-density portion DH and the low-density portion DL of the non-skinside layer 3 can be compared by known methods. For example, the thicknesses of the non-skinside layer 3 may be measured by the visual comparison method described above, a measurement method using a dial thickness gauge ID-C1012C manufactured by Mitutoyo Corporation or an equivalent device, or a microscope (VHX-1000 manufactured by Keyence Corporation) by taking an enlarged photograph of the cross section of the non-skinside layer 3 with a known dimension.

[0081] The high-density portion DH can be formed, for example, by conveying a nonwoven fabric sheet having a substantially uniform thickness (the non-skin-side layer 3 without the high-density portion DH) sandwiched between a pair of rolls during the manufacturing process of the non-skin-side layer 3. One of the pair of rolls is a heat embossing roll (or sonic embossing roll) having protrusions on its outer peripheral surface, and the other roll is an anvil roll with a smooth outer peripheral surface. By heating the fibers 3f by the heat embossing roll (or sonic embossing roll) to a temperature higher than the softening point of the latent crimped fibers of the fibers 3f of the non-skin-side layer 3, the fibers 3f are softened and made easier to process, making it easier to maintain a shape in the high-density portion DH that is thinner than the low-density portion DL.

[0082] When the non-skin side layer 3 has the high-density portion DH and the low-density portion DL having the above-mentioned characteristics, the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH obtained by the above-mentioned horse blood drop test is longer than the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL, as shown in Figure 6. Furthermore, with respect to the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH and the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL, the value obtained by dividing the longitudinal length LK1 of the diffusion region K1 by the longitudinal length LK2 of the diffusion region K2 is 1.5 or more (LK1 / LK2 ≥ 1.5). The non-skin-side layer 3 having such high-density portions DH and low-density portions DL with diffusibility is more likely to promote longitudinal diffusion of excretory fluid such as menstrual blood in the non-skin-side layer 3 than widthwise diffusion, compared to a non-skin-side layer 3 having high-density portions DH and low-density portions DL such that the longitudinal length LK1 of the diffusion region K1 divided by the longitudinal length LK2 of the diffusion region K2 is less than 1.5. Therefore, when a napkin 1 including this non-skin-side layer 3 is worn, the high-density portions DH more easily promote longitudinal diffusion of excretory fluid absorbed by the non-skin-side layer 3. By improving longitudinal diffusibility in this way, the non-skin-side layer 3 can absorb more excretory fluid by diffusing it over a wider area than by absorbing it only in a limited area, thereby improving the absorbency of the napkin 1 as a whole. In addition, by diffusing the excrement absorbed by the non-skin-side layer 3 while reducing the risk of excrement leaking from the outside in the width direction of the napkin 1, the excrement remains on the skin-side of the napkin 1 more than when it is only partially absorbed, reducing the risk of the excrement remaining in contact with the wearer's skin or leaking from the napkin 1 before being absorbed inside the napkin 1.

[0083] Furthermore, the visibility of the diffusion region K1 in the high density portion DH and the diffusion region K2 in the low density portion DL gives the wearer the impression that the napkin 1 has improved diffusion and absorption of excrement.

[0084] Furthermore, as shown in Figure 6, with respect to the horse blood diffusion region K1 in the high-density portion DH and the horse blood diffusion region K2 in the low-density portion DL obtained by the horse blood drop test, it is more preferable that the widthwise length WK1 of the horse blood diffusion region K1 in the high-density portion DH be longer than the widthwise length WK2 of the horse blood diffusion region K2 in the low-density portion DL. Because the high-density portion DH is a linear region along the longitudinal direction, it is a portion that is more likely to promote longitudinal diffusion than widthwise diffusion. Therefore, by making the widthwise length WK1 of the horse blood diffusion region K1 in the high-density portion DH longer than the widthwise length WK2 of the horse blood diffusion region K2 in the low-density portion DL, horse blood (excrement) in the high-density portion DH is more likely to promote longitudinal diffusion than widthwise outward diffusion, thereby reducing the risk of excrement leaking outward in the width direction when wearing the napkin 1.

[0085] Factors that affect the diffusion area of ​​horse blood in the horse blood drop test of the non-skin side layer 3 include, for example, the area of ​​the high density part DH and the low density part DL, the number of the high density part DH and the low density part DL, the length of the high density part DH and the low density part DL in the longitudinal direction or the width direction, the thickness of the high density part DH (corresponding to tDH in Figure 7), the basis weight of the high density part DH and the low density part DL, the density of the fiber 3f of the high density part DH and the low density part DL, and the skin side of the high density part DH and the skin side of the low density part DL. These factors include the thickness direction length between the surface (depth of the depression in the high-density section DH), the arrangement of the high-density section DH and the low-density section DL, the proportion of latently crimped fibers in the fibers 3f constituting the non-skin side layer 3, the type of fibers other than the latently crimped fibers 3f and absorbent members such as superabsorbent polymers contained in the non-skin side layer 3, the amount of fibers other than the latently crimped fibers 3f and absorbent members contained in the non-skin side layer 3, and the material constituting the latently crimped fibers 3f, such as PET / modified PET, and the proportion thereof. From these factors, a factor may be selected that satisfies the condition that the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density section DH in the non-skin side layer 3 divided by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density section DL is 1.5 or greater (LK1 / LK2≧1.5). Other factors for making the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH of the non-skin side layer 3 by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL 1.5 or more (LK1 / LK2≧1.5) are shown below. Note that the non-skin side layer 3, the high-density portion DH, and the low-density portion DL may each have one of the following factors, or a combination of two or more of the following factors.

[0086] In the non-skin side layer 3, the plurality of fibers 3f are not fused to each other. As described above, in the manufacturing process of the non-skin side layer 3, the high density portion DH can be formed by sandwiching a nonwoven fabric sheet between a pair of rolls. However, at this time, heat and pressure are applied to the high density portion DH, which may cause the plurality of fibers 3f in the high density portion DH to fuse together. Therefore, it is preferable that the high density portion DH be formed by heating the fibers 3f by one of the pair of rolls, a heat embossing roll (or sonic embossing roll), to a temperature higher than the softening point and lower than the melting point of the latent crimped fibers of the fibers 3f in the non-skin side layer 3. This makes it easier to maintain the shape of the high density portion DH while reducing the risk of the plurality of fibers 3f fusing together.

[0087] Generally, in a nonwoven fabric sheet, the fused fiber portions are formed by the fibers 3f melting and solidifying together, which tends to hinder the diffusion of excrement (liquid). On the other hand, the narrower the gaps between the fibers, the easier it is for excrement (liquid) to diffuse. Therefore, by not fusion-bonding the fibers 3f together in the high-density portion DH, the risk of hindering the diffusion of absorbed liquid (excrement) can be reduced compared to when the fibers are fused together.

[0088] Furthermore, the plurality of fibers 3f in the non-skin side layer 3 are latently crimped fibers. Because the non-skin side layer 3 is a nonwoven fabric sheet containing latently crimped fibers, the shape of the plurality of fibers is maintained by entanglement, making it easier to maintain the shape of the voids formed by the plurality of fibers. This reduces the risk of the voids formed by the fibers 3f being crushed by absorbing liquid and expanding, as with pulp fibers, making it easier to maintain the voids. Furthermore, because the latently crimped fibers 3f in the non-skin side layer 3 are spirally (coil-shaped) crimped, the spacing between the fibers 3f tends to be narrow. Furthermore, the high-density portion DH provided in the non-skin side layer 3 makes it easier to create narrow spaces between the fibers 3f. Therefore, after absorbing liquid (excrement), the non-skin side layer 3 maintains the gaps between the fibers 3f, and the capillary action caused by the high density section DH makes it easier to draw the liquid into the high density section DH, improving the absorbency of the non-skin side layer 3 and making it easier to diffuse the absorbed liquid within the non-skin side layer 3.

[0089] Furthermore, the plurality of fibers 3f of the non-skinside layer 3 are preferably composite fibers in which polyethylene terephthalate (PET) and modified PET (modified polyethylene terephthalate) are bonded side-by-side. When the plurality of fibers 3f are such potentially crimped fibers, the potentially crimped fibers are more effectively spirally crimped, and the gaps between the fibers 3f are more easily narrowed. The narrower gaps between the fibers 3f facilitate capillary action to draw excreted liquid absorbed by the napkin 1 into the non-skinside layer 3, facilitating diffusion within the non-skinside layer 3.

[0090] In the non-skinside layer 3, the average distance between the fibers 3f is set to 11 to 28 μm. If the distance between the fibers 3f is too small, it becomes difficult to retain excreted liquid in the gaps between the fibers 3f. Therefore, by setting the average distance between the fibers 3f in the non-skinside layer 3 to 11 μm or more, it becomes easier to ensure flow paths for diffusing liquid and areas for retaining liquid, compared to when the average distance between the fibers 3f in the non-skinside layer 3 is less than 11 μm. On the other hand, if the distance between the fibers 3f is too large, capillary action between the fibers 3f becomes less likely to occur. Therefore, by setting the average distance between the fibers 3f to 28 μm or less, excreted liquid absorbed by the napkin 1 is more easily drawn into the non-skinside layer 3 and its absorption is promoted by capillary action, compared to when the average distance between the fibers 3f is greater than 28 μm.

[0091] Furthermore, the value obtained by dividing the average distance between the fibers 3f in the low-density sections DL by the average distance between the fibers 3f in the high-density sections DH is set to 3.0 or more (average distance between fibers 3f in the low-density sections DL / average distance between fibers 3f in the high-density sections DH > 3.0). This makes it easier to promote diffusion of excreted fluid in the high-density sections DH by capillary action than when the value obtained by dividing the average distance between the fibers 3f in the low-density sections DL by the average distance between the fibers 3f in the high-density sections DH is less than 3.0. This improves the absorbency of excreted fluid in the non-skinside layer 3, and the improved absorbency and diffusibility of the non-skinside layer 3 more easily gives the impression to the wearer that the napkin 1 has improved absorbency and diffusibility.

[0092] <Method of calculating inter-fiber distance> The average value of the distance between the fibers 3f can be obtained by a well-known method. For example, the average value of the distance between the fibers 3f can be obtained by the following formula based on Wrotnowski's assumption. Note that, hereinafter, "inter-fiber distance" refers to the average value of the distance between the fibers.

[0093] The distance between fibers 3f is calculated by measuring the thickness of the non-skinside layer 3 to be measured and applying the result to the following formula (1). First, the non-skinside layer 3 to be measured is cut into a piece measuring 50 mm in the longitudinal direction and 50 mm in the transverse direction to prepare a cut piece of the non-skinside layer 3. This cut piece is sandwiched between the skinside layer 2 and the backsheet 4 to prepare a sanitary napkin using the non-skinside layer 3 to be measured as an absorbent layer. In the prepared sanitary napkin, the thickness of the non-skinside layer 3 is measured at a pressure of 49 Pa. The measurement environment is a temperature of 20±2°C and a relative humidity of 65±5%, and a microscope (VHX-1000, manufactured by Keyence Corporation) is used as the measuring device. An enlarged photograph of the cross section of the non-skinside layer 3 is then obtained. An object with known dimensions is also photographed on the enlarged photograph. A scale is aligned with the enlarged photograph of the cross section of the non-skinside layer 3, and the thickness of the non-skinside layer 3 is measured. The above operation is carried out three times, and the average of the three measurements is taken as the thickness [mm] of the dry non-skin side layer 3. In the case of a laminated product, the boundary is determined from the fiber diameter and the thickness is calculated.

[0094] Next, the inter-fiber distance of the fibers constituting the non-skin side layer 3 to be measured is calculated by the following formula based on Wrotnowski's assumption. The formula based on Wrotnowski's assumption is generally used to calculate the inter-fiber distance of the fibers constituting a nonwoven fabric. According to the formula based on Wrotnowski's assumption, the inter-fiber distance A (μm) is calculated by the thickness h (mm) and basis weight e (g / m ２ ), the fiber diameter d (μm) of the fibers constituting the nonwoven fabric, the fiber density ρ (g / cm ３ ) can be calculated using the following equation (1).

[0095] The fiber diameter d (μm) was determined by measuring the cross sections of 10 cut fibers using a scanning electron microscope (DSC6200 manufactured by Seiko Instruments Inc.) and averaging the results to determine the fiber diameter. ３The basis weight e (g / m) is measured using a density gradient tube in accordance with the density gradient tube method described in JIS L1015, Chemical Fiber Staple Test Method. ２ ) is cut to a predetermined size (e.g., 0.12 m x 0.06 m), and after measuring the weight, the basis weight is calculated using the following formula: Weight ÷ Area calculated from predetermined size = Basis weight (g / m ２ )

[0096]

[0097] The distance between fibers 3f in the non-skinside layer 3 of the napkin 1 of this embodiment is calculated for each of the high-density portion DH and the low-density portion DL based on the above-mentioned formula (1). For example, the thickness, basis weight, fiber diameter, and fiber density of the nonwoven fabric in each portion DH and DL in the non-skinside layer 3 can be as follows: [High-density portion DH] Nonwoven fabric thickness h: 0.32 mm Basis weight e: 121.00 g / m ２ Fiber diameter d of fibers 3f constituting non-skin side layer 3: 17.00 μm Fiber density ρ: 1.360 g / cm ３ Calculating the inter-fiber distance A from these values, the inter-fiber distance A in the high density portion DH is 11.75 μm. [Low density portion DL] Nonwoven fabric thickness h: 0.79 mm Basis weight e: 121.00 g / m ２ Fiber diameter d of fibers 3f constituting non-skin side layer 3: 17.00 μm Fiber density ρ: 1.360 g / cm ３ When the inter-fiber distance A is calculated from these values, the inter-fiber distance A in the low density portion DL is 27.92 μm.

[0098] Furthermore, as mentioned above, in absorbent articles such as napkin 1, the width of napkin 1 and the non-skin-side layer 3 is shorter than the length in the longitudinal direction, and therefore by promoting the diffusion of excreted liquid in the longitudinal direction, the risk of excreted liquid leaking outward in the width direction of napkin 1 when worn can be reduced.

[0099] In the non-skin side layer 3, low-density portions DL are adjacent to both sides of the high-density portion DH in the longitudinal direction. For example, as shown in Fig. 7, a plurality of high-density portions DH are arranged intermittently in the longitudinal direction along an imaginary straight line L of the non-skin side layer 3. The imaginary straight line L is an imaginary straight line extending along and parallel to the longitudinal direction. In addition, low-density portions DL are provided adjacent to each high-density portion DH on the front and rear sides in the longitudinal direction.

[0100] The napkin 1 of this embodiment has a plurality of high density portions DH arranged at predetermined intervals in the width direction, each high density portion DH being continuous in the longitudinal direction from the upper end to the lower end of the non-skin side layer 3. As shown in Fig. 7 , each high density portion DH along one longitudinal direction has a wave-like shape in which convex portions protruding toward one side in the width direction (e.g., the left side) and convex portions protruding toward the other side in the width direction (e.g., the right side) are alternately arranged.

[0101] The high-density portion DH of the non-skin-side layer 3 is a portion that easily draws in liquid by capillary action because the voids formed by the fibers 3f are small due to the high density of the fibers 3f. While the high-density portion DH is easily able to draw in liquid, its small voids result in a low liquid retention capacity. The low-density portion DL has larger voids than the high-density portion DH, so it draws in less liquid than the high-density portion DH, but its large voids result in a high liquid retention capacity. For this reason, by providing low-density portions DL on both longitudinal sides of the high-density portion DH of the non-skin-side layer 3, liquid that has once been absorbed (retained) in the low-density portion DL is easily drawn into the high-density portion DH adjacent to the low-density portion DL from one longitudinal side. Liquid that has been drawn into the high-density portion DH and cannot be completely retained can diffuse into the adjacent low-density portion DL from one longitudinal side of the high-density portion DH. Doing this once or multiple times facilitates the longitudinal diffusion of liquid.

[0102] As shown in FIG. 7 and other figures, the non-skin-side layer 3 is provided with a plurality of high-density portions DH. Preferably, these high-density portions DH are spaced apart from one another in the width direction. That is, adjacent high-density portions DH do not abut (overlap) each other in the width direction, and continuous low-density portions DL are provided between adjacent high-density portions DH in the width direction. As described above, the high-density portions DH are more likely to absorb excreted liquid than the low-density portions DL due to capillary action. If adjacent high-density portions DH abut each other in the width direction, excreted liquid is likely to accumulate in the abutting areas. In contrast, by arranging the multiple high-density portions DH spaced apart from one another in the width direction, the risk of excreted liquid accumulating in areas where the multiple high-density portions DH overlap in the width direction can be reduced. Furthermore, the high-density portions DH along the longitudinal direction facilitate the longitudinal diffusion of excreted liquid absorbed by the non-skin-side layer 3.

[0103] Furthermore, the linear high-density portions DH are inclined relative to the longitudinal direction, and have portions where the smaller angle between the longitudinal direction and the high-density portions DH is 45 degrees or less. In the napkin 1, as shown in FIG. 7, the high-density portions DH are inclined relative to the longitudinal direction, and have portions where the smaller angle θ1 between the virtual line L and the high-density portions DH is 45 degrees or less. This makes it easier to promote the liquid absorption in the high-density portions DH and the liquid retention in the low-density portions DL in the longitudinal direction as described above, compared to when high-density portions DH are provided parallel to the longitudinal direction, thereby facilitating the diffusion of liquid in the longitudinal direction. Note that all of the smaller angles between the longitudinal direction and the high-density portions DH may be 45 degrees or less, or at least one of the smaller angles between the longitudinal direction and the high-density portions DH may be 45 degrees or less, and may have a portion where the angle is greater than 45 degrees.

[0104] When the longitudinal length of the non-skinside layer 3 is divided into thirds, with the front portion of the third divided into the front region 31, the central portion divided into the central region 32, and the rear portion divided into the rear region 33, the high-density portion DH has a portion that continues from the upper end to the lower end of the central region 32. The central region 32 is a region that is likely to come into contact with the excretory opening when the napkin is worn. By having the high-density portion DH of the non-skinside layer 3 have a portion that continues from the upper end to the lower end of the central region 32, excreted body waste is more likely to be dispersed in the longitudinal direction at least in the central region 32. This reduces the risk of excreta being locally retained in the napkin 1 and the risk of excreta leaking outward in the lateral direction of the napkin 1.

[0105] As shown in Figure 8, a bottomed recess is formed in the high-density portion DH. In other words, the high-density portion DH does not have any intentionally penetrating portions in the thickness direction, unlike the voids formed by the fibers 3f. Even when the high-density portion DH has a bottomed recess, it is easy to promote the diffusion of liquid in the non-skinside layer 3. Furthermore, in cases such as napkin 1, where the skinside layer 2 is located closer to the skin than the non-skinside layer 3 and the recess in the non-skinside layer 3 is located on the skin side, the recess in the high-density portion DH is easily separated from the skinside layer 2, which reduces the risk of excrement once absorbed by the non-skinside layer 3 returning to the skinside layer 2 and reduces discomfort to the wearer's skin. 8, the non-skin side layer 3 of the napkin 1 may have recesses on both the skin side and the non-skin side of the non-skin side layer 3, or the skin side may have a recess recessed toward the non-skin side and the non-skin side may be flat, or the skin side of the non-skin side layer 3 may be flat and the non-skin side may have a recess recessed toward the skin side. Furthermore, the recesses on the skin side and the non-skin side may be located at the same position or at different positions in the thickness direction.

[0106] The non-skin side layer 3 also has the following water retention rate for distilled water. The weight of the non-skin side layer 30 before absorbing liquid is defined as the pre-absorption weight (A1). The weight of the non-skin side layer 3 after immersing it in distilled water for 60 seconds and then removing it from the distilled water and hanging it for 90 seconds is defined as the post-absorption weight (A2). The weight (A2) after absorption is subtracted by the pre-absorption weight (A1) to define the retained weight (A3) of distilled water in the non-skin side layer 3. Post-absorption weight (A2) - pre-absorption weight (A1) = retained weight (A3). The water retention rate of distilled water in the non-skin side layer 3 can be calculated by dividing this retained weight (A3) by the pre-absorption weight (A1). For the non-skin side layer 3, it is preferable that the value obtained by dividing the retained weight (A3) by the pre-absorption weight (A1) is 8 or more. Retained weight (A3) / pre-absorption weight (A1) ≥ 8

[0107] <Moisture Retention Test> The moisture retention rate of the non-skinside layer 3 for distilled water can be obtained by the following moisture retention test. Fig. 9 is a diagram illustrating the moisture retention test. The moisture retention test may be performed on the entire non-skinside layer 3 of the napkin 1, or on a sample obtained by cutting the non-skinside layer 3 to a predetermined size. In the following, an example will be described in which a sample 30 obtained by cutting the non-skinside layer 3 to a rectangular shape with a longitudinal length of 120 mm and a width of 35 mm is used.

[0108] First, as shown in FIG. 9A , the weight of the sample 30 before absorbing the liquid is measured to obtain the pre-absorption weight (A1). Next, as shown in FIG. 9B , the sample 30 is immersed in distilled water for 60 seconds. At this time, the sample 30 is completely submerged in the distilled water. After 60 seconds of immersion, the sample 30 is removed from the distilled water and suspended for 90 seconds using a clip CP or the like, as shown in FIG. 9C . After 90 seconds of suspension, the weight of the sample 30 is measured to obtain the post-absorption weight (A2). The post-absorption weight (A2) obtained by the measurement is subtracted by the pre-absorption weight (A1) to obtain the retained weight (A3) of distilled water of the sample 30. The water retention of the sample 30 and the non-skin side layer 3 can then be obtained by dividing the retained weight (A3) by the pre-absorption weight (A1).

[0109] In this way, when the value obtained by dividing the retained weight (A3) by the pre-absorption weight (A1) of the non-skin side layer 3 is 8 or more, the non-skin side layer 3 and the napkin 1 can retain more excrement than when the value obtained by dividing the retained weight (A3) by the pre-absorption weight (A1) is less than 8. This reduces the risk of excrement leaking from the napkin 1 using such a non-skin side layer 3.

[0110] 10, the non-skin side layer 3 includes at least one fiber 3f that is a potentially crimped fiber and whose curling direction is inclined at an angle θ2 of more than 55 degrees with respect to the direction of the axis J. Fig. 10 is a diagram illustrating the curling of the fiber 3f. Even when the non-skin side layer 3 includes at least one potentially crimped fiber 3f that is inclined at an angle θ2 of more than 55 degrees with respect to the direction of the axis J, it is possible to improve the absorbency of excreted liquid within the non-skin side layer 3, while still giving the impression to the wearer that the napkin 1 has improved absorbency and diffusion of excreted liquid.

[0111] As described above, the napkin 1 has a liquid-impermeable backsheet (non-skin-side sheet) 4 located on the non-skin-side side of the non-skin-side layer 3. The napkin 1 has a portion where the non-skin-side sheet 3 and the backsheet 4 abut. In the napkin of this embodiment, the non-skin-side layer 3 and the backsheet 4 are adjacent to each other in the thickness direction and secured together with a hot-melt adhesive or the like. In the napkin 1, the backsheet 4 constitutes the non-skin-side surface of the napkin 1 and is provided with an adhesive portion on the non-skin-side surface for securing the napkin 1 to clothing when worn. Having a portion where the non-skin-side layer 3 and the backsheet 4 abut makes it easier to visually observe the diffusion state of excrement absorbed by the non-skin-side layer 3 through the backsheet 4 from the non-skin side of the napkin 1 after it has absorbed excrement. This makes it easier for the wearer to recognize that the napkin 1 has a non-skin-side layer 3 with improved diffusibility.

[0112] As described above, the napkin 1 has a non-skinside layer 3 and a skinside layer 2 (skinside sheet), with the skinside layer 2 having voids (first voids) formed by a plurality of fibers 2f, and the non-skinside layer 3 having voids (second voids) formed by a plurality of fibers 3f. For each of these voids, the proportion of voids (second voids) in the non-skinside layer 3 in a void ratio evaluation test for quantitatively evaluating the proportion of voids in a predetermined area is preferably smaller than the proportion of voids (first voids) in the skinside layer 2 in the void ratio evaluation test. In the napkin 1, by providing a high-density portion DH throughout the entire non-skinside layer 3, the proportion of voids (second voids) in the non-skinside layer 3 in the void ratio evaluation test is made smaller than the proportion of voids (first voids) in the skinside layer 2 in the void ratio evaluation test. When the napkin 1 absorbs excrement, capillary action tends to draw the excrement from the skin-side layer 2 to the non-skin-side layer 3, which has a smaller proportion of voids, and this tends to promote diffusion of the excrement within the non-skin-side layer 3. Furthermore, since it tends to reduce the amount of excrement remaining in the skin-side layer 2 when the napkin 1 is worn, it is possible to alleviate discomfort caused by excrement coming into contact with the wearer's skin.

[0113] Note that the method of making the proportion of voids (second voids) in the non-skin side layer 3 smaller than the proportion of voids (first voids) in the skin side layer 2 in the void ratio evaluation test is not limited to providing a high density portion DL in the non-skin side layer 3. For example, the non-skin side layer 3 may be compressed as a whole in the thickness direction to crush the non-skin side layer 3 in the thickness direction, thereby reducing the voids formed by the fibers 3f. Furthermore, the thickness (fiber diameter) of the fibers 3f of the non-skin side layer 3 may be made thinner than the thickness (fiber diameter) of the fibers 2f of the skin side layer 2. Furthermore, the fibers 3f of the non-skin side layer 3 may be made of latent crimp fibers that have a stronger crimping property than the fibers 2f of the skin side layer 2.

[0114] <Void Ratio Evaluation Test Method> A void ratio evaluation test for the skin side layer 2 and the non-skin side layer 3 of the napkin 1 of this embodiment was carried out by Toray Research Center, Inc. The void ratio evaluation test can be carried out, for example, by the following method.

[0115] First, X-ray CT measurements are performed on the skin-side layer 2 and the non-skin-side layer 3. Non-destructive tomography (CT measurements) is performed using a Rigaku high-resolution 3D X-ray microscope nano3DX under the following conditions: X-ray source: Cu Tube voltage-tube current: 40 kV-30 mA Detector: sCMOS camera (lens: 1080) Resolution: 2.51 μm / voxel

[0116] Measurement areas (predetermined areas) of the skin side layer 2 and the non-skin side layer 3 are randomly extracted from the three-dimensional data obtained by photography, and voids are analyzed. The measurement areas for this analysis are rectangular parallelepipeds (or cubes) whose thickness direction lengths are the thicknesses H2, H3 of the skin side layer 2 and the non-skin side layer 3 within any range in the planar direction of the skin side layer 2 and the non-skin side layer 3.

[0117] The tomographic image obtained by X-ray CT shows low-density (void) components that easily transmit X-rays in black, and high-density (fiber) components that easily absorb X-rays in white. From this image, the void ratios in the measurement areas of the skin-side layer 2 and non-skin-side layer 3 are calculated.

[0118] The void ratios of the skin side layer 2 and the non-skin side layer 3 can be calculated by obtaining the void volumes in the measurement areas of the skin side layer 2 and the non-skin side layer 3 and the volume of the measurement areas from tomographic images obtained by X-ray CT. For example, the void ratio of the non-skin side layer 3 is as follows: Void ratio of non-skin side layer 3 = (Volume of voids in non-skin side layer 3) / (Volume of non-skin side layer 3) The volume of the non-skin side layer 3 is the sum of the volume of the fibers in the non-skin side layer 3 and the volume of the voids in the non-skin side layer 3.

[0119] In the napkin 1 of the above-described embodiment, an adhesive such as a hot melt adhesive is provided between the components stacked in the thickness direction to secure the components, but this is not limited to this. An adhesive need not be provided between the skinside layer 2 and the non-skinside layer 3. In particular, an adhesive need not be provided between the skinside layer 2 and the non-skinside layer 3 in the central portion of the napkin 1 in the width direction. This reduces the risk that the adhesive will interfere with the absorption of excrement in the skinside layer 2 and the non-skinside layer 3, and also reduces the risk that the adhesive will interfere with the diffusion of excrement from the skinside layer 2 to the non-skinside layer 3, thereby reducing the risk that excrement will remain in the skinside layer 2.

[0120] Below, we will specifically explain the non-skinside layer 3 (nonwoven fabric sheet) by illustrating several examples and comparative examples in which the conditions for the high-density section DH and the low-density section DL were changed. However, the present invention is not limited to these examples. Figure 11 shows the measurement results for each example and comparative example. Note that, below, measurements were performed on nonwoven fabric sheets that can be used as the non-skinside layer 3, Examples A to F, and Comparative Examples 1 and 2, which correspond to the non-skinside layer 3, each having a rectangular shape with a longitudinal length of 120 mm and a lateral length of 35 mm. Each of Examples A to F and Comparative Examples 1 and 2 is formed solely with potentially crimped fibers (fibers 3f), and the nonwoven fabric sheets are formed with the same amount and weight of fibers 3f. Furthermore, Examples A to F and Comparative Example 2 have high-density sections DH with a shape similar to that shown in Figures 4 and 7. However, the thicknesses of the high-density section DH and the low-density section DL are different in Examples A to F and Comparative Example 2. The thickness, interfiber distance, horse blood drop test, and water retention test in Figure 11 each show the results of measurement using the above-mentioned methods. The thickness of the low-density section DL is the average value of the results of measuring the thickness of the thickest part of each nonwoven fabric sheet eight times, and the thickness of the high-density section DH is the average value of the results of measuring the thickness of the thinnest part of each nonwoven fabric sheet eight times. The interfiber distance is calculated from the measured thickness of the low-density section DL and the high-density section DH, and is the average interfiber distance calculated from the eight measurement results. The result of the water retention test is the average value of the measurement results three times.

[0121] Example A In the nonwoven fabric sheet of Example A, the high density portion DH is formed by batch production, not by a pair of rolls. The measurement results of the nonwoven fabric sheet of Example A are as follows. 88 English: Thickness of low-density section DL: 1.21 mm Fiber-to-fiber distance in low-density section DL: 46 μm Thickness of high-density section DH: 0.3 mm Fiber-to-fiber distance in high-density section DH: 22.9 μm Fiber-to-fiber distance in low-density section DL / Fiber-to-fiber distance in high-density section DH: 2.0 <Horse blood drop test> Longitudinal length LK1 of diffusion region K1 in high-density section DH: 90.5 mm Longitudinal length LK2 of diffusion region K2 in low-density section DL: 29.5 mm LK1 / LK2: 3.07 <Water retention test> Weight before absorption: 0.557 g Weight after absorption: 3.831 g Retained weight: 3.274 g Water retention rate: 5.88 It is clear that in the nonwoven fabric sheet of Example A, the thickness of the high-density section DH along the longitudinal direction is thinner than the low-density section DL. It is clear that in the horse blood drop test, the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density region DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density region DL was 1.5 or more. In the nonwoven fabric sheet of Example A, the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density region DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density region DL was 1.5 or more, which improves the absorbency and diffusibility of excrement in an absorbent article including the nonwoven fabric sheet of Example A and makes it easier for the wearer to recognize that the absorbent article has improved absorbency and diffusibility.

[0122] (Example B) The high density portion DH of the nonwoven fabric sheet of Example B was formed by being sandwiched between a sonic embossing roll having protrusions on its outer peripheral surface and an anvil roll having a smooth outer peripheral surface while being conveyed. The measurement results of the nonwoven fabric sheet of Example B are as follows. 4.927g Retained weight: 4.443g Water retention: 9.18 It is clear that the thickness of the high density portion DH along the longitudinal direction is thinner than that of the low density portion DL in the nonwoven fabric sheet of Example B. Furthermore, the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0. It is clear that the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL in a horse blood drop test is 1.5 or greater. The water retention rate in a water retention test is 8 or greater. The nonwoven fabric sheet of Example B has a value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL of 1.5 or greater, thereby improving the excrement absorption and diffusion properties of an absorbent article including the nonwoven fabric sheet of Example B and making it easier for the wearer to recognize that the absorbent article has improved absorption and diffusion properties. Furthermore, since the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0, the absorbency of excrement within the nonwoven fabric sheet of Example B can be improved, and an absorbent article including the nonwoven fabric sheet of Example B has improved absorbency and diffusibility, which makes it easier to give the impression to the wearer that the absorbent article has improved absorbency and diffusibility. Furthermore, since the water retention rate in the water retention test is 8 or more, the nonwoven fabric sheet of Example B can retain a large amount of excrement.Therefore, the risk of excrement leaking from an absorbent article using this nonwoven fabric sheet can be reduced.

[0123] (Example C) The high density portion DH of the nonwoven fabric sheet of Example C was formed by conveying the sheet between a heat embossing roll having protrusions on its outer peripheral surface and an anvil roll having a smooth outer peripheral surface. The measurement results of the nonwoven fabric sheet of Example C are as follows. 8.55 English: Thickness of low-density section DL: 1.46 mm Fiber-to-fiber distance in low-density section DL: 50.5 μm Thickness of high-density section DH: 0.09 mm Fiber-to-fiber distance in high-density section DH: 12.5 μm Fiber-to-fiber distance in low-density section DL / Fiber-to-fiber distance in high-density section DH: 4.0 <Horse blood drop test> Longitudinal length LK1 of diffusion region K1 in high-density section DH: 83 mm Longitudinal length LK2 of diffusion region K2 in low-density section DL: 30 mm LK1 / LK2: 2.77 <Water retention test> Weight before absorption: 0.518 g Weight after absorption: 4.947 g Retained weight: 4.429 g Water retention rate: 8.55 It is clear that in the nonwoven fabric sheet of Example C, the thickness of the high-density section DH along the longitudinal direction is thinner than that of the low-density section DL. Furthermore, the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0. It is clear that in a horse blood drop test, the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL is 1.5 or greater. The water retention rate in a water retention test is 8 or greater. The nonwoven fabric sheet of Example C has a value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL of 1.5 or greater, thereby improving the excrement absorption and diffusion properties of an absorbent article including the nonwoven fabric sheet of Example C and making it easier for the wearer to recognize that the absorbent article has improved absorption and diffusion properties. Furthermore, since the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0, the absorbency of excrement within the nonwoven fabric sheet of Example C can be improved, and an absorbent article including the nonwoven fabric sheet of Example C has improved absorbency and diffusibility, making it easier to give the impression to the wearer that the absorbent article has improved absorbency and diffusibility. Furthermore, since the water retention rate in the water retention test is 8 or more, the nonwoven fabric sheet of Example C can retain a large amount of excrement.Therefore, the risk of excrement leaking from an absorbent article using this nonwoven fabric sheet can be reduced.

[0124] (Example D) The high density portion DH of the nonwoven fabric sheet of Example D was formed by conveying the sheet between a heat embossing roll having protrusions on its outer peripheral surface and an anvil roll having a smooth outer peripheral surface. The measurement results of the nonwoven fabric sheet of Example D are as follows. Thickness of low-density section DL: 1.41 mm Fiber-to-fiber distance in low-density section DL: 49.6 μm Thickness of high-density section DH: 0.08 mm Fiber-to-fiber distance in high-density section DH: 11.8 μm Fiber-to-fiber distance in low-density section DL / Fiber-to-fiber distance in high-density section DH: 4.2 <Horse blood drop test> Longitudinal length LK1 of diffusion region K1 in high-density section DH: 78 mm Longitudinal length LK2 of diffusion region K2 in low-density section DL: 36.5 mm LK1 / LK2: 2.14 <Water retention test> Weight before absorption: 0.496 g Weight after absorption: 4.63 g Retained weight: 4.134 g Water retention rate: 8.33 It is clear that the thickness of the high-density section DH along the longitudinal direction is thinner than that of the low-density section DL in the nonwoven fabric sheet of Example D. Furthermore, the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0. It is clear that the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL in a horse blood drop test is 1.5 or greater. The water retention rate in a water retention test is 8 or greater. The nonwoven fabric sheet of Example D has a value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL of 1.5 or greater, thereby improving the excrement absorption and diffusion properties of an absorbent article including the nonwoven fabric sheet of Example D and making it easier for the wearer to recognize that the absorbent article has improved absorption and diffusion properties. Furthermore, since the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0, the absorbency of excrement within the nonwoven fabric sheet of Example D can be improved, and an absorbent article including the nonwoven fabric sheet of Example D has improved absorbency and diffusibility, which makes it easier to give the impression to the wearer that the absorbent article has improved absorbency and diffusibility. Furthermore, since the water retention rate in the water retention test is 8 or more, the nonwoven fabric sheet of Example D can retain a large amount of excrement.Therefore, the risk of excrement leaking from an absorbent article using this nonwoven fabric sheet can be reduced.

[0125] (Example E) The high density portion DH of the nonwoven fabric sheet of Example E was formed by conveying the sheet between a sonic embossing roll having protrusions on its outer peripheral surface and an anvil roll having a smooth outer peripheral surface. The measurement results of the nonwoven fabric sheet of Example E are as follows. 8mm LK1 / LK2: 2.55 <Water retention test> Weight before absorption: 0.493g Weight after absorption: 4.621g Retained weight: 4.128g Water retention: 8.37 It is clear that the thickness of the high density portion DH along the longitudinal direction is thinner than that of the low density portion DL in the nonwoven fabric sheet of Example E. Furthermore, the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0. It is clear that in a horse blood drop test, the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL is 1.5 or greater. The water retention rate in a water retention test is 8 or greater. The nonwoven fabric sheet of Example E has a value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL of 1.5 or greater, thereby improving the excrement absorption and diffusion properties of an absorbent article including the nonwoven fabric sheet of Example E and making it easier for the wearer to recognize that the absorbent article has improved absorption and diffusion properties. Furthermore, since the value obtained by dividing the inter-fiber distance in the low-density section DL by the inter-fiber distance in the high-density section DH is greater than 3.0, the absorbency of excretory liquid within the nonwoven fabric sheet of Example E can be improved, and an absorbent article equipped with the nonwoven fabric sheet of Example E has improved absorbency and diffusion properties, making it easier to give the impression to the wearer and others that the absorbent article has improved absorbency and diffusion properties.Furthermore, since the water retention rate in the water retention test was 8 or more, the nonwoven fabric sheet of Example E was able to retain a large amount of excrement, thereby reducing the risk of excrement leaking from absorbent articles using this nonwoven fabric sheet.

[0126] (Example F) The high density portion DH of the nonwoven fabric sheet of Example F was formed by conveying the sheet between a sonic embossing roll having protrusions on its outer peripheral surface and an anvil roll having a smooth outer peripheral surface. The measurement results of the nonwoven fabric sheet of Example F are as follows. 4.917g Water retention test Weight before absorption: 0.539g Weight after absorption: 4.917g Retained weight: 4.378g Water retention rate: 8.12 It is clear that the thickness of the high density portion DH along the longitudinal direction is thinner than that of the low density portion DL in the nonwoven fabric sheet of Example F. Furthermore, the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0. It is clear that in a horse blood drop test, the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL is 1.5 or greater. The water retention rate in a water retention test is 8 or greater. The nonwoven fabric sheet of Example F has a value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density portion DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density portion DL of 1.5 or greater, thereby improving the excrement absorption and diffusion properties of an absorbent article including the nonwoven fabric sheet of Example F and making it easier for the wearer to recognize that the absorbent article has improved absorption and diffusion properties. Furthermore, since the value obtained by dividing the inter-fiber distance in the low-density portion DL by the inter-fiber distance in the high-density portion DH is greater than 3.0, the absorbency of excrement within the nonwoven fabric sheet of Example F can be improved, and an absorbent article including the nonwoven fabric sheet of Example F has improved absorbency and diffusibility, making it easier to give the impression to the wearer that the absorbent article has improved absorbency and diffusibility. Furthermore, since the water retention rate in the water retention test is 8 or more, the nonwoven fabric sheet of Example F can retain a large amount of excrement.Therefore, the risk of excrement leaking from an absorbent article using this nonwoven fabric sheet can be reduced.

[0127] (Comparative Example 1) The nonwoven fabric sheet of Comparative Example 1 does not have a high density portion DH. In other words, the nonwoven fabric sheet of Comparative Example 1 is configured with the thickness and fiber density of the low density portion DL throughout the entire area, and the thickness of this nonwoven fabric sheet is approximately constant throughout the entire area, and the fiber density is also approximately constant. The measurement results of the nonwoven fabric sheet of Example F are as follows. In Example F, since the high density portion DH is not provided, the measurement results are only for the low density portion DL. Thickness of low density portion DL (thickness of nonwoven fabric sheet of Example F): 2.0 mm Fiber distance of low density portion DL: 59.1 μm <Water retention test> Weight before absorption: 0.633 g Weight after absorption: 6.84 g Retained weight: 6.207 g Water retention rate: 9.81

[0128] (Comparative Example 2) The high density portion DH of the nonwoven fabric sheet of Comparative Example 2 was formed by conveying the sheet between a sonic embossing roll having protrusions on its outer peripheral surface and an anvil roll having a smooth outer peripheral surface. The measurement results of the nonwoven fabric sheet of Comparative Example 2 are as follows. 80 English: Thickness of low-density section DL: 1.43 mm Fiber-to-fiber distance in low-density section DL: 50 μm Thickness of high-density section DH: 0.3 mm Fiber-to-fiber distance in high-density section DH: 22.9 μm Fiber-to-fiber distance in low-density section DL / Fiber-to-fiber distance in high-density section DH: 2.2 <Horse blood dropping test> Length LK1 in the longitudinal direction of diffusion region K1 in high-density section DH: 23 mm Length LK2 in the longitudinal direction of diffusion region K2 in low-density section DL: 23 mm LK1 / LK2: 1.00 <Water retention test> Weight before absorption: 0.519 g Weight after absorption: 5.243 g Retained weight: 4.724 g Water retention: 9.10 In the nonwoven fabric sheet of Comparative Example 2, the thickness of the high-density section DH along the longitudinal direction was thinner than the low-density section DL, but the difference in thickness between the high-density section DH and the low-density section DL was smaller than in Examples A to F described above. Furthermore, the value obtained by dividing the interfiber distance in the low-density section DL by the interfiber distance in the high-density section DH was less than 3.0. In the horse blood drop test of the nonwoven fabric sheet of Comparative Example 2, the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density section DH and the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density section DL were the same value. Therefore, the value obtained by dividing the longitudinal length LK1 of the horse blood diffusion region K1 in the high-density section DH by the longitudinal length LK2 of the horse blood diffusion region K2 in the low-density section DL was 1.00, and it is clear that the value obtained by dividing LK1 by LK2 was less than 1.5. In other words, in the nonwoven fabric sheet of Comparative Example 2, horse blood dropped onto the nonwoven fabric sheet of Comparative Example 2 diffuses equally in both the longitudinal and width directions. Therefore, when the nonwoven fabric sheet of Comparative Example 2 is used in an absorbent article such as napkin 1, the longitudinal and widthwise diffusion proceeds in the same manner, and therefore, if the diffusion area in the absorbent article is expanded, the diffusion of excrement in the widthwise direction also expands, making it easier for excrement to leak outward in the widthwise direction of the absorbent article, thereby reducing the absorbency and diffusion properties of the absorbent article.

[0129] ===Other Embodiments===The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

[0130] In the above-described embodiment, the skin side layer 2 and the non-skin side layer 3 are nonwoven fabric sheets formed of the latently crimped fibers 2 f and 3 f, respectively, and used as absorbents. However, this is not limiting. The skin side layer 2 may be disposed as a top sheet instead of an absorbent, and a flexible sheet such as an air-through nonwoven fabric, a spunbond nonwoven fabric, or an SMS nonwoven fabric (spunbond-meltblown-spunbond nonwoven fabric) may be used.

[0131] REFERENCE SIGNS LIST 1 napkin (sanitary napkin, absorbent article), 1w wing portion, 2 skin side layer (skin side sheet), 2f latently crimped fiber (fiber), 3 non-skin side layer (nonwoven fabric sheet), 31 front region, 32 central region, 33 rear region, 3f latently crimped fiber (fiber), 4 back sheet (non-skin side sheet), 5 side sheet, 10 absorbent layer, 20 compressed portion, DH high density portion (first region), DL low density portion (second region)

Claims

1. A nonwoven fabric sheet for use in absorbent articles, comprising a plurality of fibers in a longitudinal direction, a transverse direction, and a thickness direction that intersect with one another, and which, when viewed in the thickness direction, has a first region and a second region, the first region being a linear region extending in the longitudinal direction, having a higher fiber density than the second region and being thinner than the second region, and the first region and the second region being arranged so that, 5 minutes after 0.5 ml of horse blood is dropped onto the center of the nonwoven fabric sheet, the value obtained by dividing the longitudinal length of the horse blood diffusion region in the first region by the longitudinal length of the horse blood diffusion region in the second region is 1.5 or more.

2. The nonwoven fabric sheet according to claim 1, wherein the plurality of fibers are not fused to one another.

3. A nonwoven fabric sheet according to claim 1 or 2, characterized in that the plurality of fibers comprise latent crimp fibers.

4. A nonwoven fabric sheet according to claim 3, characterized in that the latent crimped fibers are composite fibers in which polyethylene terephthalate and modified polyethylene terephthalate are bonded side-by-side.

5. A nonwoven fabric sheet according to claim 1 or 2, characterized in that the value obtained by dividing the average distance between fibers in the second region by the average distance between fibers in the first region is 3.0 or more.

6. A nonwoven fabric sheet according to claim 1 or 2, characterized in that the nonwoven fabric sheet is an absorbent that absorbs liquid.

7. A nonwoven fabric sheet according to claim 1 or 2, wherein the length of the nonwoven fabric sheet in the longitudinal direction is longer than the length of the nonwoven fabric sheet in the lateral direction, and the second region is adjacent to each of the first region on both sides in the longitudinal direction.

8. A nonwoven fabric sheet according to claim 1 or 2, wherein the length of the nonwoven fabric sheet in the longitudinal direction is longer than the length of the nonwoven fabric sheet in the transverse direction, the first region is inclined with respect to the longitudinal direction, and the nonwoven fabric sheet has a portion in which the smaller angle between the longitudinal direction and the first region is 45 degrees or less.

9. A nonwoven fabric sheet according to claim 1 or 2, wherein the length of the nonwoven fabric sheet in the longitudinal direction is longer than the length in the lateral direction, a plurality of the first regions are provided, and the plurality of first regions are arranged at a distance from each other in the lateral direction.

10. A nonwoven fabric sheet according to claim 1 or 2, wherein the length in the longitudinal direction of the nonwoven fabric sheet is longer than the length in the transverse direction, and when the length in the longitudinal direction of the nonwoven fabric sheet is divided into thirds and the central portion in the longitudinal direction is defined as the central portion, the first region has a portion that is continuous from the upper end to the lower end of at least the central portion.

11. The nonwoven fabric sheet according to claim 1 or 2, wherein the average distance between the fibers is 11 to 28 μm.

12. A nonwoven fabric sheet according to claim 1 or 2, wherein the first region has a recess with a bottom.

13. The nonwoven fabric sheet according to claim 1 or 2, wherein the basis weight of the fibers of the nonwoven fabric sheet is 80 gsm or more and 140 gsm or less.

14. A nonwoven fabric sheet according to claim 1 or 2, characterized in that the nonwoven fabric sheet is placed in the crotch area of ​​the wearer when the absorbent article is worn.

15. A nonwoven fabric sheet according to claim 1 or 2, characterized in that when the weight of the nonwoven fabric sheet before absorbing liquid is defined as the pre-absorption weight, the weight of the nonwoven fabric sheet after immersing the nonwoven fabric sheet in distilled water for 60 seconds and then removing it from the distilled water and hanging it for 90 seconds is defined as the post-absorption weight, and the value obtained by subtracting the post-absorption weight from the pre-absorption weight is defined as the weight of distilled water retained by the nonwoven fabric sheet, the value obtained by dividing the retained weight by the pre-absorption weight is 8 or more.

16. A nonwoven fabric sheet according to claim 3, characterized in that the winding direction of at least one of the latent crimped fibers is inclined at an angle θ of more than 55 degrees relative to the axial direction.

17. An absorbent article comprising the nonwoven fabric sheet according to claim 1 or 2, characterized in that it has a liquid-impermeable non-skin-side sheet provided on the non-skin side of the nonwoven fabric sheet, and the nonwoven fabric sheet has a portion that abuts against the non-skin-side sheet.

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