Absorbent body and absorbent article

Abstract

An absorbent body (10) used in an absorbent article (1), the absorbent body (10) comprising at least one nonwoven fabric (2, 3) provided with a plurality of fibers (2f, 3f) containing potentially crimped fibers, the absorbent body (10) having voids formed by the plurality of fibers (3f), and the value obtained by dividing the weight of the potentially crimped fibers by the weight of the plurality of fibers being 70% or more.

Description

Technical Field

[0001] The present invention relates to an absorber and an absorbent article. Background Art

[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 surface sheet disposed on the skin contact surface side, a back sheet disposed on the non-skin contact surface side, and an absorber disposed between the surface sheet and the back sheet. The absorber of Patent Document 1 is formed of pulp fibers or the like.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-176412 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In a worn state of an absorbent article such as a sanitary napkin disclosed in Patent Document 1, when excrement is absorbed, the humidity becomes particularly high. Therefore, there is a concern that the wearer easily feels stuffy, and the absorbent article loses its elasticity or deforms due to long-term wearing or the like, causing discomfort to the wearer. Therefore, it is desired to improve the air permeability of the absorbent article and reduce the deformation of the absorbent article even in the worn state.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide an absorber that improves air permeability and reduces loss of elasticity and deformation.

[0009] Means for Solving the Problems

[0010] A main invention for achieving the above object is an absorber for an absorbent article, characterized in that the absorber is composed of at least one nonwoven fabric including a plurality of fibers including latent crimp fibers, the absorber has voids formed by the plurality of fibers, and a value obtained by dividing the weight of the latent crimp fibers by the weight of the plurality of fibers is 70% or more.

[0011] Other features of the present invention will be clarified by the description of this specification and the drawings.

[0012] Effects of the Invention

[0013] According to the present invention, an absorber can be formed that holds excrement using voids formed by fibers, improves air permeability, and reduces loss of elasticity and deformation. Brief Description of the Drawings

[0014] Figure 1It is a top view obtained by observing the sanitary napkin 1 from the skin side.

[0015] Figure 2 It is a schematic cross-sectional view taken along the line A-A of the sanitary napkin 1.

[0016] Figure 3 It is a diagram for explaining the structure of the sanitary napkin 1.

[0017] Figure 4 It is a diagram for explaining the absorbent layer 10 of the sanitary napkin 1.

[0018] Figure 5 A is a diagram schematically showing the cross-section of the skin side layer 2. Figure 5 B is a diagram schematically showing the cross-section of the non-skin side layer 3.

[0019] Figure 6 It schematically shows Figure 4 the schematic cross-section taken along the line B-B in

[0020] Figure 7 It is a diagram for explaining the sanitary napkin 1 after 30 minutes have passed since horse blood was dropped.

[0021] Figure 8 It is a diagram for explaining the measurement area Y.

[0022] Figure 9 It is a diagram for explaining the outline of the evaluation method for the narrowness in the gap Z.

[0023] Figure 10 It is a diagram showing the measurement results of the absorption test of the absorbent layer 10.

[0024] Figure 11 A is a diagram showing the measurement results of the bending characteristics of the absorbent layer 10 based on the KES method. Figure 11 B is a diagram showing the measurement results of the compression characteristics of the absorbent layer 10 based on the KES method.

[0025] Figure 12 It is a diagram showing the measurement results of the elongation test of the absorbent layer 10.

[0026] Figure 13 It is a diagram for explaining the sanitary napkin 100 which is a modified example of the present embodiment.

[0027] Figure 14 It is a diagram for explaining the skin side layer 2 of the sanitary napkin 100. Detailed implementation mode

[0028] According to the description of this specification and the drawings, at least the following matters become clear.

[0029] (Solution 1)

[0030] An absorber for absorbent articles, characterized in that the absorber is composed of at least one nonwoven fabric having a plurality of fibers including latent crimped fibers, the absorber has voids formed by the plurality of fibers, and the value obtained by dividing the weight of the latent crimped fibers by the weight of the plurality of fibers is 70% or more.

[0031] The absorber according to Solution 1 can be formed into an absorber that holds excrement using the voids formed by the fibers and improves air permeability, reduces loss of elasticity, and deformation.

[0032] (Solution 2)

[0033] For the absorber described in Solution 1, the air permeability resistance value is 0.32 kpa·s / m or less.

[0034] The absorber according to Solution 2 can improve the air permeability of the absorbent article compared to the case where the air permeability resistance value is greater than 0.32 kpa·s / m, and thus can reduce the discomfort of the wearer of the absorbent article.

[0035] (Solution 3)

[0036] For the absorber described in Solution 1 or 2, the plurality of fibers are not fused to each other.

[0037] The absorber according to Solution 3 can reduce the concern that the fused part hinders the absorption and diffusion of excrement.

[0038] (Solution 4)

[0039] For the absorber described in any one of Solutions 1 to 3, the absorber has a thickness direction and has voids formed by the plurality of fibers. When the absorber is trisected in the thickness direction and the region closest to the skin side is set as the skin side region, the region closest to the non-skin side is set as the non-skin side region, and the region between the skin side region and the non-skin side region is set as the intermediate region, the average narrowness of the non-skin side region in the narrowness evaluation test for quantitatively evaluating the narrowness of the voids is smaller than the average narrowness of the skin side region in the narrowness evaluation test.

[0040] The absorber according to Solution 4 can easily introduce excrement from the skin side region to the non-skin side region by capillary action and easily spread the excrement in the non-skin side region, and thus can reduce the concern that excrement remains on the surface of the skin side region.

[0041] (Solution 5)

[0042] According to the absorber described in any one of Schemes 1 to 4, the absorber has a thickness direction and has voids formed by the plurality of fibers. When the absorber is trisected in the thickness direction and the region closest to the skin side is set as the skin-side region, the region closest to the non-skin side is set as the non-skin side region, and the region between the skin-side region and the non-skin side region is set as the intermediate region, the void ratio of the non-skin side region in the void ratio evaluation test for quantitatively evaluating the ratio of the voids in a predetermined region is smaller than the void ratio of the skin-side region in the void ratio evaluation test.

[0043] According to the absorber of Scheme 5, it is easy to introduce excrement into the non-skin side region compared to the skin side region by capillary action, and it is easy to spread the excrement in the non-skin side region. Therefore, the concern that liquid remains on the surface of the skin side region can be reduced.

[0044] (Scheme 6)

[0045] According to the absorber described in any one of Schemes 1 to 5, the absorber has a thickness direction and has voids formed by the plurality of fibers. When the absorber is trisected in the thickness direction and the region closest to the skin side is set as the skin-side region, the region closest to the non-skin side is set as the non-skin side region, and the region between the skin-side region and the non-skin side region is set as the intermediate region, the hydrophilicity of the skin-side region is lower than the hydrophilicity of the non-skin side region.

[0046] According to the absorber of Scheme 6, it is easy to promote the excrement absorbed in the skin-side region to go towards the non-skin side region, and it is easy to spread the excrement in the non-skin side region. Therefore, the concern that the excrement stays on the surface of the skin side region can be reduced, and the discomfort of the wearer can be reduced.

[0047] (Scheme 7)

[0048] According to the absorber described in any one of Schemes 1 to 6, the absorber has a thickness direction and has voids formed by the plurality of fibers. When the absorber is trisected in the thickness direction and the region closest to the skin side is set as the skin-side region, the region closest to the non-skin side is set as the non-skin side region, and the region between the skin-side region and the non-skin side region is set as the intermediate region, at least a part of the fibers in the non-skin side region has a higher hydrophilicity than the fibers in the skin-side region, and a part of the fibers in the non-skin side region is exposed to the skin-side surface of the absorber.

[0049] In the absorber according to Embodiment 7, the fibers in the exposed non-skin side region are prone to introducing the excrement absorbed from the skin side toward the non-skin side region, facilitating the diffusion of excrement within the non-skin side region, and reducing the concern about liquid remaining on the surface of the skin side region.

[0050] (Embodiment 8)

[0051] In the absorber according to any one of Embodiments 1 to 7, the absorber has a thickness direction. When a portion closer to the skin side than the center in the thickness direction of the absorber is defined as the first region and a portion closer to the non-skin side than the center in the thickness direction of the absorber is defined as the second region, the maximum value of the fiber thickness in the first region is larger than the maximum value of the fiber thickness in the second region.

[0052] In the absorber according to Embodiment 8, the coarser the fiber thickness, the easier it is for the voids formed by the fibers to become larger. Therefore, it is easy to introduce excrement into the second region with smaller voids and facilitate the diffusion of the excrement in the second region, reducing the concern about the excrement continuously contacting the wearer and reducing the discomfort of the wearer.

[0053] (Embodiment 9)

[0054] In the absorber according to any one of Embodiments 1 to 8, the basis weight per unit area of the plurality of fibers of the absorber is 80 gsm or more and 350 gsm or less.

[0055] In the absorber according to Embodiment 9, compared with the case where the basis weight per unit area of the fibers of the absorber is less than 80 gsm, the absorber is prone to absorbing excrement. Compared with the case where the basis weight per unit area of the fibers of the absorber is greater than 350 gsm, the concern about the absorber becoming too thick and too hard can be reduced.

[0056] (Embodiment 10)

[0057] In the absorber according to any one of Embodiments 1 to 9, the absorber has a length direction, a width direction, and a thickness direction. The length in the length direction of the absorber is longer than the length in the width direction, and the bending stiffness B in the KES method at the central portion in the length direction and the central portion in the width direction of the absorber is 1.2 gf·cm 2 / cm or less.

[0058] In the absorber according to Embodiment 10, compared with the case where the bending stiffness B of the absorber is greater than 1.2 gf·cm 2 / cm, the absorbent article can be made softer, and thus it is easy to follow the body of the wearer wearing the absorbent article.

[0059] (Embodiment 11)

[0060] The absorber according to any one of Schemes 1 to 10 has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, and the bending hysteresis 2HB in the KES method at the central portion in the length direction and the central portion in the width direction of the absorber is 0.93 gf·cm 2 / cm or less.

[0061] For the absorber according to Scheme 11, compared with the case where the bending hysteresis 2HB of the absorber is greater than 0.93 gf·cm 2 / cm, it is easier to restore the deformed absorber in the worn state to its original shape, and it is possible to reduce the discomfort caused to the wearer by the deformation of the absorber or reduce the concern about leakage of excrement from the absorber.

[0062] (Scheme 12)

[0063] The absorber according to any one of Schemes 1 to 11 has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, and the linearity LC of the compression characteristic in the KES method at the central portion in the length direction and the central portion in the width direction of the absorber is 0.6 or more.

[0064] For the absorber according to Scheme 12, compared with the case where the linearity LC of the compression characteristic of the absorber is less than 0.6, the absorber can be made more resistant to compression, so that the deformation of the absorber can be reduced, and thus the discomfort caused to the wearer due to the deformation of the absorber or the concern about leakage of excrement from the absorber can be reduced.

[0065] (Scheme 13)

[0066] The absorber according to any one of Schemes 1 to 12 has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, and the compression resilience RC in the KES method at the central portion in the length direction and the central portion in the width direction of the absorber is 38.0% or more.

[0067] For the absorber according to Scheme 13, compared with the case where the compression resilience of the absorber is less than 38%, it is easier to restore the shape of the absorber in the worn state, so that the discomfort caused to the wearer by the deformation of the absorber or the concern about leakage of excrement from the absorber can be reduced.

[0068] (Scheme 14)

[0069] According to the absorber described in any one of Schemes 1 to 13, in an elongation test for measuring the magnitude of the force for elongating the length in the longitudinal direction of the absorber to 1.3 times the length in the longitudinal direction of the absorber, the value obtained by dividing the value of the magnitude of the force measured in the 10th measurement of the elongation test of the absorber by the value of the magnitude of the force measured in the 1st measurement of the elongation test of the absorber is 50% or more.

[0070] According to the absorber of Scheme 14, an absorbent article can be formed such that, compared with the case where the value obtained by dividing the value of the magnitude of the force measured in the 10th measurement of the elongation test by the value of the magnitude of the force measured in the 1st measurement of the elongation test is less than 50%, since the value obtained by dividing the value of the magnitude of the force measured in the 10th measurement of the elongation test by the value of the magnitude of the force measured in the 1st measurement of the elongation test is 50% or more, it is easy to reduce breakage of the absorber even in a worn state and it is easy to follow the shape and movement of the wearer's body.

[0071] (Scheme 15)

[0072] According to the absorbent article described in any one of Schemes 1 to 13, it has a longitudinal direction, a width direction, and a thickness direction. The length in the longitudinal direction of the absorber is longer than the length in the width direction. When observing along the thickness direction, the central portion in the longitudinal direction and the central portion in the width direction of the absorbent article are set as a predetermined area. The weight of the predetermined area before absorbing distilled water is set as the pre-absorption weight. The weight of the predetermined area after dipping the predetermined area in distilled water for 60 seconds, pulling it out of the distilled water, and hanging it for 90 seconds is set as the post-absorption weight. The value obtained by subtracting the pre-absorption weight from the post-absorption weight is set as the absorption weight of the distilled water. At this time, the value obtained by dividing the absorption weight by the pre-absorption weight is 5 or more.

[0073] According to the absorbent article of Scheme 15, compared with the case where the value obtained by dividing the absorption weight by the pre-absorption weight is less than 5, it is easy to ensure the liquid absorption function of the absorbent article and it is easy to diffuse the absorbed liquid in a larger range in the absorber.

[0074] ===Embodiment===

[0075] As the absorbent article of the present invention, the sanitary napkin 1 (hereinafter also referred to as "sanitary napkin 1") is taken as an example to illustrate the embodiments. However, the absorbent article of the present invention may also be an adult or infant panty-type disposable diaper, a belt-type disposable diaper, a sanitary short, a sanitary napkin, a light incontinence pad, an absorbent pad, an animal disposable diaper, an absorbent sheet, a fresh water absorbent pad (Japanese: ドリップシート), etc. In addition, in the case of a fresh water absorbent pad or the like, the "wearing state" in the following embodiments becomes the "using state", and the wearer becomes the "user, etc.". Hereinafter, the wearing state will also be referred to as the "using state", and the wearer will also be referred to as the "user, etc.".

[0076] <<<Structure of sanitary napkin 1>>>

[0077] Figure 1 It is a top view obtained by observing the sanitary napkin 1 (hereinafter also referred to as "sanitary napkin") from the skin side. Figure 2 It is a schematic cross-sectional view taken along the line A-A of the sanitary napkin 1. Figure 3 It is a diagram for explaining the structure of the sanitary napkin 1. The sanitary napkin 1 has a length direction, a width direction, and a thickness direction that are orthogonal to each other. The side in contact with the wearer's skin in the thickness direction 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) in the wearing state, and is also referred to as the "absorbent surface side". The non-skin side in the thickness direction is the opposite side of the absorbent surface side, and is also referred to as the "non-absorbent surface side". Figure 1 The center line C-C shown in etc. represents the center (central position) in the width direction of the sanitary napkin 1. Figure 4

[0078] The sanitary napkin 1 has a skin side layer (non-woven fabric sheet) 2, a non-skin side layer (non-woven fabric sheet) 3, a backsheet 4, and side flaps 5. As shown in Figure 3 etc., the sanitary napkin 1 is sequentially stacked with the side flaps 5, the skin side layer 2, the non-skin side layer 3, and the backsheet 4 in order from the skin side in the thickness direction. Each member stacked in the thickness direction is fixed to each other by an adhesive such as a hot melt adhesive.

[0079] The skin side layer 2 is a skin side sheet located at the most skin-side position in the central portion in the width direction of the sanitary napkin 1, and is an absorbent member that comes into contact with the excretory opening and bears the excrement discharged from the excretory opening in the wearing state. The skin side layer 2 has a substantially rectangular shape that is longer in the length direction, and the length L2 in the length direction is longer than the length W2 in the width direction. By disposing the skin side layer 2 at the crotch position of the wearer in the wearing state of the sanitary napkin 1, when the sanitary napkin 1 absorbs excrement, the skin side layer 2 can absorb the excrement and cause the absorbed excrement to diffuse toward the non-skin side layer 3. Therefore, it is possible to reduce the discomfort to the wearer caused by the leakage of excrement from the sanitary napkin 1 or the local stay of excrement on the surface of the skin side layer 2 or the like.

[0080] The non-skin side layer 3 is a non-skin side sheet provided between the skin side layer 2 and the backsheet 4 in the thickness direction. The non-skin side layer 3 is smaller in size than the skin side layer 2 when viewed from above. The non-skin side layer 3 has a generally rectangular shape that is longer in the length direction, and the length L3 in the length direction is longer than the length W3 in the width direction. The non-skin side layer 3 is an absorption member that absorbs and holds the excrement absorbed by the skin side layer 2. By disposing the non-skin side layer 3 at the crotch position of the wearer in the worn state of the sanitary napkin 1, when the sanitary napkin 1 absorbs excrement, the non-skin side layer 3 can absorb the excrement and allow the excrement to diffuse within the non-skin side layer 3. Therefore, it is possible to reduce the discomfort to the wearer caused by leakage of excrement from the sanitary napkin 1 or local retention of excrement on the surface of the skin side layer 2 or the like.

[0081] The skin side layer 2 and the non-skin side layer 3 are each a non-woven fabric (non-woven fabric sheet) composed of latent crimp fibers 2f and latent crimp fibers 3f (refer to Figure 5 ). The skin side layer 2 and the non-skin side layer 3 of the present embodiment are non-woven fabrics formed only of latent crimp fibers (100% latent crimp fibers). However, for the layers (non-woven fabrics) constituting the skin side layer 2 and the non-skin side layer 3, in addition to using latent crimp fibers, fibers composed of polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters (PET, PBT), polyamides, etc., and their composite fibers can also be used. In addition, hydrophilic fibers such as rayon, pulp, and cotton can also be used. Hereinafter, the latent crimp fiber 2f will also be simply referred to as "fiber 2f", and the latent crimp fiber 3f will be simply referred to as "fiber 3f".

[0082] "Non-woven fabric" refers to a fabric formed as follows: in a fiber sheet, mesh, or mat, the fibers are oriented in one direction or randomly, and the fibers are joined together by interlacing, and / or fusing, and / or bonding (JIS L0222:2001 Non-woven fabric terminology 101). That is, a non-woven fabric is a fabric that integrates without weaving fibers and is a sheet material having a breaking strength of 5 [N] / 25 mm or more. The breaking strength can be measured by a known method. For example, it can be measured by the following method. Use a tensile testing machine (manufactured by Shimadzu Corporation: AUTOGRAPH, AGS-1kNG) equipped with a load cell having a maximum load capacity of 50 N. When measuring the separation strength of the non-woven fabric sheet, hold the front end of one side in the long side direction or short side direction of the non-woven fabric sheet with one chuck, and hold the other side of the non-woven fabric sheet with the other chuck. Using the tensile testing machine, stretch the two chucks at a constant speed (example: 100 mm / min) so that the distance between the two chucks increases, and measure the load applied to the two chucks. The load at which the non-woven fabric sheet breaks is defined as the breaking strength.

[0083] Examples of non-woven fabrics include: non-woven fabrics obtained by the meltblowing method (meltblown non-woven fabrics), non-woven fabrics obtained by the electrospinning method (electrospun non-woven fabrics), non-woven fabrics obtained by the spunbond method (spunbond non-woven fabrics), non-woven fabrics manufactured by the hot air method (hot air non-woven fabrics), non-woven fabrics manufactured by the hydroentangling method (hydroentangled non-woven fabrics), or non-woven fabrics manufactured by the needling method (needled non-woven fabrics), or laminates of two or more of these non-woven fabrics, or laminates of these non-woven fabrics and non-woven fabrics other than these non-woven fabrics and other materials. The skin-side layer 2 and the non-skin-side layer 3 of the present embodiment are each a hydroentangled non-woven fabric in which fibers are intertwined with each other by water flow without using an adhesive.

[0084] The non-woven fabric sheet of the skin-side layer 2 of the sanitary napkin 1 of the present embodiment is formed by the hydroentangling method through the following steps.

[0085] (a) First, hydrophilic fibers 2fb (fibers 2f that form at least a part of the non-skin-side region Rd to be described later) are processed using a carding machine or the like to form a non-skin-side fiber web having a form such as a carded web.

[0086] (b) Next, while transporting the non-skin-side fiber web, a skin-side fiber web having a form such as a carded web, which is obtained by processing hydrophobic fibers 2fa (fibers 2f that form at least a part of the skin-side region Ru) using a carding machine or the like, is supplied onto and laminated on the non-skin-side fiber web to obtain a laminated web.

[0087] (c) By applying high-pressure water flow such as a water jet from the skin side to the non-skin side in the thickness direction of the laminated web, the fibers between the fiber layers and the fibers of each web are intertwined with each other to obtain a laminate.

[0088] (d) Finally, the laminate is put into a dryer and heated to a temperature at which the latent shrinkable fibers can shrink, whereby an integrated non-woven fabric sheet (skin-side layer 2) is obtained. This non-woven fabric sheet has voids formed by a plurality of fibers 2f.

[0089] The non-woven fabric sheet of the non-skin-side layer 3 of the sanitary napkin 1 of the present embodiment is also formed by the same method as the non-woven fabric sheet of the skin-side layer 2. However, the non-woven fabric sheet of the non-skin-side layer 3 is different from the skin-side layer 2 in that instead of using hydrophobic fibers, only a web of hydrophilic fibers 3f is laminated.

[0090] The latent crimp fibers 2f and 3f are fibers that are crimped by heat treatment to exhibit a helical shape. Among the latent crimpable fibers, for example, there are side-by-side composite fibers in which a high-shrinkage component and a low-shrinkage component are arranged side by side, and eccentric core-sheath type composite fibers in which the high-shrinkage component is the core and the low-shrinkage component is the sheath, and the centers of gravity of the two components do not overlap at a single point. When the latent crimpable fibers are made to exhibit crimp, the latent crimpable fibers are crimped, for example, in a coiled shape.

[0091] As the plurality of resins having different thermal shrinkage rates or thermal expansion rates for forming the latent crimp fibers 2f and 3f, any combination of resins having different thermal shrinkage rates or thermal expansion rates can be used without particular limitation, and it can also be a combination of the same type or single resin, or a combination of different types of resins. As a specific example of the combination of resins having different thermal shrinkage rates or thermal expansion rates for forming the latent crimp fibers, for example, latent crimpable fibers that are combinations of polyester resins with each other or combinations of polyamide resins with each other can be adopted.

[0092] The non-woven fabrics of the skin-side layer 2 and the non-skin-side layer 3 in the present embodiment are combinations of polyester resins (single-component resins) with each other. Specifically, latent crimpable fibers that are combinations of polyethylene terephthalate (PET) and modified PET are used. In addition, the modified PET is obtained by copolymerizing a glycol component other than ethylene glycol or a dicarboxylic acid component other than terephthalic acid as a minor component with ethylene glycol and terephthalic acid, which are the constituent components of PET, for modification. As specific examples of the glycol component other than ethylene glycol, for example, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene ether glycol, etc. can be cited. In addition, as specific examples of the dicarboxylic acid component other than terephthalic acid, for example, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, etc. can be cited. And a web formed of latent crimpable fibers that are combinations of PET and modified PET is formed by a web forming unit such as a carding machine, and the fibers of the web are interlaced with each other by a hydroentangling method to become a non-woven fabric state, and the web is heated to a predetermined temperature to make the latent crimpable fibers exhibit crimp. Thus, the non-woven fabrics of the skin-side layer 2 and the non-skin-side layer 3 are produced. Thus, the unit area weight of the latent crimp fibers of the heated non-woven fabric is larger than the unit area weight of the latent crimpable fibers in the non-woven fabric state before heating. That is to say, the non-woven fabric shrinks due to the crimp of the latent crimpable fibers, and the unit area weight of the fibers becomes larger.

[0093] The skin-side layer 2 and the non-skin-side layer 3 are each an absorbent layer 10 having a liquid permeability, a liquid absorption function, and a liquid retention function, and having a predetermined thickness. In the present embodiment, the absorbent body of the present invention will be described as the absorbent layer 10. Figure 4 This is a view for explaining the absorbent layer 10 of the sanitary napkin 1. In the sanitary napkin 1, the skin-side layer 2 is a skin-side sheet that comes into contact with the skin of the wearer. It is a member that first bears excrement in the worn state, and is a member that absorbs the excrement received in the skin-side layer 2 and allows the excrement to permeate toward the non-skin side. The non-skin-side layer 3 is a member that absorbs and retains the excrement permeated from the skin-side layer 2.

[0094] As Figure 5 shown, the skin-side layer 2 and the non-skin-side layer 3 each have voids formed by a plurality of fibers (latent crimped fibers) 2f, 3f. Figure 5 A is a view schematically showing a cross section of the skin-side layer 2, Figure 5 B is a view schematically showing a cross section of the non-skin-side layer 3, and the dimensions and the like are not necessarily accurate. In addition, the voids in the skin-side layer 2 and the non-skin-side layer 3 may be voids between non-continuous (a plurality of fibers) fibers, or may be voids formed by a single continuous fiber being bent or formed into a spiral shape, or may be voids formed by a combination of the above voids. The voids formed by a plurality of fibers 2f, 3f refer to spaces or regions in the skin-side layer 2 and the non-skin-side layer 3 where a plurality of fibers 2f, 3f are not provided. In addition, the voids are not only spaces surrounded by fibers 2f, 3f or spaces enclosed by fibers, but may also be spaces where at least a part of the voids formed by the fibers 2f, 3f is open.

[0095] Since the skin-side layer 2 and the non-skin-side layer 3 each have latent crimped fibers 2f, 3f, they are formed in a spiral shape in such a way that the fibers 2f, 3f are wound around each other shuttling between the fibers 2f, 3f by the crimping of the fibers 2f, 3f. For example, the distance between the fibers 2f, 3f is shortened due to the crimping, or other fibers enter between the fibers 2f, 3f whose distance has been shortened, and the voids between the fibers 2f, 3f become further smaller. Therefore, the voids formed by the fibers 2f, 3f including the latent crimped fibers are smaller than the voids formed by a plurality of fibers in a normal non-woven fabric formed of non-crimped fibers.

[0096] In addition, for the potential crimped fibers 2f and 3f provided in the skin side layer 2 and the non-skin side layer 3 respectively, the fibers themselves are not easily absorbent of liquid. For example, in fibers such as pulp fibers, when they absorb liquid (excrement), the thickness of the fibers becomes thicker. However, even when the potential crimped fibers 2f and 3f in the skin side layer 2 and the non-skin side layer 3 come into contact with liquid, the inside of the fibers is not easily absorbent of liquid. Therefore, in the skin side layer 2 and the non-skin side layer 3, in the worn state, even when the sanitary napkin 1 absorbs excrement, for the potential crimped fibers 2f and 3f in the skin side layer 2 and the non-skin side layer 3, the thickness of the fibers themselves is not easily thickened. Since the thickness of the fibers themselves is not easily thickened, the size of the voids formed by the fibers 2f and 3f is not easily reduced, and the voids are not easily flattened. Thus, in the skin side layer 2 and the non-skin side layer 3, liquid (excrement) can be retained in the voids formed by the fibers 2f and 3f. Therefore, the skin side layer 2 and the non-skin side layer 3 are respectively layers that can allow liquid to pass through and are layers that can absorb and retain liquid. In addition, the skin side layer 2 and the non-skin side layer 3 are respectively non-woven fabric sheets formed by the fibers 2f and 3f, having voids formed by the fibers 2f and 3f, and thus have excellent air permeability, can reduce the stuffiness and skin roughness brought to the wearer in the worn state, and can improve the comfort of the worn state.

[0097] As described above, the potential crimped fibers 2f in the skin side layer 2 are potential crimped fibers that are a combination of PET and modified PET, and fibers of the same thickness are used throughout the area. In the present embodiment, the thickness of the potential crimped fiber 2fa is set to 2.2 dtex. In addition, the average narrow width of the voids in the skin side layer 2 is 104 μm. And the ratio of the voids in the skin side layer 2 (the ratio of the area in the skin side layer 2 where the fibers 2f are not provided) is 94%. The unit area weight of the skin side layer 2 is about 170 gsm. In addition, in the skin side layer 2, preferably, hydrophobic fibers are used on the skin side and hydrophilic fibers are used on the non-skin side.

[0098] All of the potential crimped fibers 3f in the non-skin side layer 3 are potential crimped fibers that are a combination of PET and modified PET, and fibers of the same thickness are used throughout the entire area in the thickness direction. The thickness of the potential crimped fiber 3f in the non-skin side layer 3 of the present embodiment is set to 2.2 dtex. The unit area weight of the non-skin side layer 3 is about 120 gsm. Preferably, the unit area weight of the fibers 3f in the non-skin side layer 3 is 80 gsm or more and 200 gsm or less.

[0099] The non-skin side layer 3 has a linear high-density portion DH where the density of the fibers 3f is higher than the surrounding (low-density portion DL) and a low-density portion DL where the density of the fibers 3f is lower than the high-density portion DH. The high-density portion DH is a portion where the thickness is thinner than the surrounding (low-density portion DL) and the fibers are not fused to each other.

[0100] The backsheet 4 is a liquid-impermeable sheet material (outer layer) disposed on the non-skin side of the non-skin side layer 3. As the liquid-impermeable sheet material, a resin film of polyethylene (PE) or the like can be exemplified. The side sheets 5 are sheets extending outward from both side portions in the width direction of the skin side surface of the skin side layer 2. As the side sheets 5, a hydrophobic thermally bonded nonwoven fabric, a hydrophobic spunbond nonwoven fabric, or the like can be exemplified.

[0101] In addition, the sanitary napkin 1 has a pair of wings 1w extending outward in the width direction at a substantially central portion in the length direction. The wings 1w are formed by the side sheets 5 and the backsheet 4. Further, the sanitary napkin 1 may not necessarily have the wings 1w. When the sanitary napkin 1 does not have the wings 1w, the side sheets 5 may or may not be provided.

[0102] In addition, the sanitary napkin 1 has a compression portion 20 formed by the skin side layer 2 and the non-skin side layer 3 being recessed in the thickness direction. The compression portion 20 can be used to fix the positions of the skin side layer 2 and the non-skin side layer 3 or to improve the liquid diffusibility of the sanitary napkin 1.

[0103] In the compression portion 20, the thickness of the sanitary napkin 1 is thinner than that of the surroundings, and the fiber density of the sanitary napkin 1 (the skin side layer 2 and the non-skin side layer 3) becomes higher. These comparisons are preferably made by known methods. As a comparison of the thickness of the sanitary napkin 1, a method of comparing by visual observation, a method of obtaining a value measured by applying pressure to an object portion, for example, at 3.0 gf / cm 2 using a dial thickness gauge ID-C1012C manufactured by Mitutoyo Corporation or an equivalent instrument and comparing the values can be exemplified. As a comparison of the density of the sanitary napkin 1, a method of comparing based on an image obtained by magnifying a cross section of the sanitary napkin 1 cut in the thickness direction using an electron microscope or the like can be exemplified. In addition, the shape of the compression portion 20 is not limited to Figure 1 the shape shown. For example, it may be a shape in which a plurality of dot-like compression portions are discretely arranged.

[0104] <<<Regarding the absorbent layer 10>>>

[0105] As described above, the absorbent layer 10 is an absorbent body for the sanitary napkin 1 having a predetermined thickness and having a liquid absorption function and a liquid retention function. That is, the skin-side layer 2 can absorb and retain liquid. The non-skin-side layer 3 can absorb and retain liquid. And, in the sanitary napkin 1, the skin-side layer 2 and the non-skin-side layer 3 are used as an absorbent body in a state of overlapping each other in the thickness direction. That is, the sanitary napkin 1 includes two non-woven fabric sheets having fibers 2f and 3f, and the fibers 2f and 3f include latent crimp fibers. The absorbent layer 10 has voids formed by a plurality of fibers 2f and 3f. Specifically, the skin-side layer 2 has a plurality of fibers 2f including latent crimp fibers and has voids formed by the fibers 2f. The non-skin-side layer 3 has a plurality of fibers 3f including latent crimp fibers and has voids formed by the fibers 3f. In the absorbent layer 10, the value obtained by dividing the weight of the latent crimp fibers by the weight of the plurality of fibers 2f and 3f is 70% or more.

[0106] The absorbent layer 10 of the sanitary napkin 1 is a structure in which the skin-side layer 2 and the non-skin-side layer 3 each having an absorption function are overlapped with each other. In addition, the skin-side layer 2 and the non-skin-side layer 3 can be fixed with an adhesive such as a hot melt adhesive, or an adhesive may not be provided. In particular, when observing the sanitary napkin 1 in the thickness direction, an adhesive is not provided between the skin-side layer 2 and the non-skin-side layer 3 at the central portion in the width direction, whereby the concern that the absorption of excrement is hindered by the adhesive in the wearing state can be reduced.

[0107] The skin-side layer 2 is a non-woven fabric sheet having a thickness of H2 and is composed of a plurality of fibers 2f. The non-skin-side layer 3 is a non-woven fabric sheet having a thickness of H3 and is composed of a plurality of fibers 3f. That is, the absorbent layer 10 is composed of two non-woven fabrics having a thickness of H10 (H2 + H3). And, in each layer, the voids formed by the plurality of fibers 2f and 3f can absorb and retain excrement, and the voids are used to improve air permeability. By improving the air permeability of the absorbent layer 10, the discomfort such as stuffiness felt by the wearer of the sanitary napkin 1 in the wearing state can be reduced. In addition, in the absorbent layer 10, compared with the case where the value obtained by dividing the weight of the latent crimp fibers by the weight of the plurality of fibers 2f and 3f is less than 70%, when the value obtained by dividing the weight of the latent crimp fibers by the weight of the plurality of fibers 2f and 3f is 70% or more, it is easy to make the non-woven fabric sheets in the absorbent layer 10 firm and soft and elastic by the crimped fibers. Therefore, the loss of elasticity and deformation of the absorbent layer 10 can be reduced. For the sanitary napkin 1 using the absorbent layer 10, the leakage of excrement caused by the loss of elasticity and deformation of the absorbent layer 10 or the discomfort and discomfort brought to the wearer due to the loss of elasticity and deformation of the absorbent layer 10 can be reduced, and the comfort during wearing can be improved.

[0108] The absorbent layer 10 of the present embodiment includes a skin-side layer 2 composed only of latent crimp fibers (100% latent crimp fibers) of fiber 2f and a non-skin-side layer 3 composed only of latent crimp fibers (100% latent crimp fibers) of fiber 3f. Therefore, the value obtained by dividing the weight of the latent crimp fibers by the plurality of fibers 2f and 3 is 100%.

[0109] In addition, the fibers 2f and 3f in the absorbent layer 10 do not necessarily have to be only latent crimp fibers (100% latent crimp fibers). It is also possible that either one or both of the fibers 2f and 3f contain fibers other than latent crimp fibers (for example, liquid-absorbent fibers such as pulp fibers). Even in such a case, as long as the value obtained by dividing the weight of the latent crimp fibers in the entire absorbent layer 10 by the weight of the plurality of fibers 2f and 3f is 70% or more. Additionally, it is also possible that the absorbent layer 10 contains not only the fibers 2f and 3f but also a superabsorbent polymer (SAP) or the like.

[0110] Regarding this absorbent layer 10, preferably, the air permeability resistance value is 0.32 kpa·s / m or less. Compared with the case where the air permeability resistance value is greater than 0.32 kpa·s / m, by setting the air permeability resistance value of the absorbent layer 10 of the sanitary napkin 1 to 0.32 kpa·s / m or less, the air permeability of the sanitary napkin 1 can be improved, and thus the discomfort such as stuffiness felt by the wearer of the sanitary napkin 1 can be reduced.

[0111] The measurement of the air permeability resistance value of the absorbent layer 10 can be carried out using a known method. For example, the absorbent layer 10 is cut out in a predetermined size (for example, a circle with a diameter of 70 mm × 70 mm) and set as a sample. Then, using a gas permeability tester (KES-F8) manufactured by Kato Tech Co., Ltd. or an equivalent gas permeability tester, the standard air permeability speed is set to 2 cm / s, and the air permeability resistance value of the sample is measured. By performing this measurement multiple times (for example, 5 times), the average value can be set as the air permeability resistance value of the absorbent layer 10.

[0112] In addition, if the fibers 2f of the skin-side layer 2 and the fibers 3f of the non-skin-side layer 3 are welded, the welded part becomes a part where the voids are flattened. Therefore, there is a concern that the absorption function may decrease, or the skin-side layer 2 and the non-skin-side layer 3 may become hard due to the welding of the fibers 2f and 3f. Therefore, in the absorbent layer 10, preferably, the plurality of fibers 2f and 3f are not welded to each other. Thereby, the concern that the absorption and diffusion of excrement in the absorbent layer 10 are hindered and the absorption function in the absorbent layer 10 decreases can be reduced. Additionally, the concern that the absorbent layer 10 becomes hard due to welding can be reduced.

[0113] Figure 6 schematically shows Figure 4A diagram of a schematic cross-section viewed in the B-B direction in []. In the thickness direction of the absorbent layer 10, the side in contact with the wearer's skin (the side that receives liquid) is the skin side, and the side opposite to the skin side is the non-skin side (non-absorbent surface side). The absorbent layer 10 is trisected in the thickness direction, the region closest to the skin side is set as the skin side region Qu, the region closest to the non-skin side is set as the non-skin side region Qd, and the region between the skin side region Qu and the non-skin side region Qd is set as the intermediate region Qm.

[0114] In the narrowness evaluation test for quantitatively evaluating the narrowness of the voids formed by the fibers 2f and 3f, the average narrowness of the non-skin side region Qd is narrower than the average narrowness of the skin side region Qu in the narrowness test. The narrowness evaluation test will be described later. Therefore, the non-skin side region Qd is more likely to introduce liquid (excrement) by capillary action than the skin side region Qu.

[0115] Generally, in absorbent articles, absorbent cores using liquid-absorbent fibers such as pulp fibers are widely used. Although the absorbent core has voids formed by liquid-absorbent fibers, there are the following situations: when the absorbent article absorbs excrement in the worn state, the liquid-absorbent fibers themselves absorb the liquid, and the thickness of the liquid-absorbent fibers themselves becomes thicker, flattening the voids. In addition, there is a concern that if the absorbed excrement stays on the skin side in the thickness direction of the absorbent article or spreads on the skin side, the diffusion area of the excrement on the skin side of the absorbent article becomes larger, giving the impression that the excrement is not absorbed within the absorbent article or that the excrement that should have been absorbed by the absorbent article comes into contact with the wearer's skin.

[0116] In contrast, the average width of the non-skin side region Qd in the width evaluation test is narrower than the average width of the skin side region Qu in the width evaluation test, so that it is easy to introduce the excrement borne by the skin side surface of the skin side region Qu in the absorption layer 10 in the wearing state into the non-skin side region Qd by means of capillary action. In addition, it is easy to make the excrement introduced into the non-skin side region Qd diffuse within a larger range in the non-skin side region Qd. Thus, in the wearing state, it is possible to reduce the situation where the excrement absorbed from the skin side surface of the skin side region Qu stays on the skin side surface of the skin side region Qu or within the skin side region Qu, and it is possible to reduce the concern that discomfort and skin roughness are likely to be caused by the continuous contact of the excrement with the wearer's skin. In addition, even when a large amount of excrement is discharged at one time, it is easy to promote the diffusion of the excrement from the skin side region Qu to the non-skin side region Qd, so that it is possible to reduce the concern that the excrement flows along the surface of the skin side region Qu and leaks from the sanitary napkin 1. In particular, as in the case of the sanitary napkin 1, when the absorption layer 10 is in contact with the wearer's skin, the average width of the non-skin side region Qd in the width evaluation test is made narrower than the average width of the skin side region Qu in the width evaluation test. Thus, it is easy to make the excrement diffuse from the skin side to the non-skin side within the absorption layer 10, so that it is possible to reduce the excrement staying on the skin side surface of the absorption layer 10 and improve the comfort of the wearer in the wearing state.

[0117] In addition, in the absorption layer 10, compared with the case where the average width of the non-skin side region Qd in the width evaluation test is wider than the average width of the skin side region Qu in the width evaluation test, by making the average width of the non-skin side region Qd in the width evaluation test narrower than the average width of the skin side region Qu in the width evaluation test, the diffusion of the excrement from the skin side region Qu to the non-skin side region Qd is promoted, so that the diffusion area of the excrement in the skin side region Qu can be made smaller and the diffusion area of the excrement in the non-skin side region Qd can be made larger. Thus, it is easy to promote the diffusion of the excrement from the skin side to the non-skin side in the absorption layer 10, and it is easy to promote the diffusion of the excrement in the part of the absorption layer 10 on the non-skin side compared with the part on the skin side. Therefore, as Figure 7 shown, it is easy to make the diffusion region B3 of the excrement in the non-skin side layer 3 larger than the diffusion region B2 of the excrement in the skin side layer 2. Figure 7 This is a diagram illustrating the sanitary napkin 1 30 minutes after dropping horse blood. Figure 7This is a diagram showing the state of the sanitary napkin 1 after 6 mm of horse blood has been dropped onto the central part in the length direction and the central part in the width direction of the sanitary napkin 1 facing the user, and 30 minutes have passed. In this way, since the area of the diffusion region B3 of the excrement in the non-skin side layer 3 is larger than the area of the diffusion region B2 of the excrement in the skin side layer 2, it is easy to give the user and others the impression that the sanitary napkin 1 has excellent absorbency.

[0118] Furthermore, the fibers 2f and 3f containing latent crimped fibers in the absorbent layer 10 of the sanitary napkin 1 itself have the property of being less likely to absorb liquids (excrement) compared to liquid-absorbent fibers such as pulp fibers. Therefore, since the absorbent layer 10 has the fibers 2f and 3f containing latent crimped fibers, even when the excrement is absorbed in the worn state, the fibers 2f and 3f themselves are not likely to thicken. That is to say, since the absorbent layer 10 has latent crimped fibers, it is easy to maintain the voids formed by the fibers 2f and 3f.

[0119] As described above, in the sanitary napkin 1 of the present embodiment, the non-woven fabric sheets of the skin side layer 2 and the non-skin side layer 3 are formed by the hydroentangling method. By pouring water flows from the skin side toward the non-skin side respectively, it is easy to press the fibers 2f and 3f from the skin side toward the non-skin side. As a result, the average narrow width of the non-skin side region Qd in the narrow width evaluation test becomes narrower than the average narrow width of the skin side region Qu in the narrow width evaluation test. In addition, when comparing the skin side layer 2 and the non-skin side layer 3 constituting the absorbent layer 10, the average narrow width of the non-skin side layer 3 in the narrow width evaluation test is narrower than the average narrow width of the skin side layer 2 in the narrow width evaluation test. The difference in the average narrow width of each layer can be set according to, for example, the amounts of the fibers 2f and 3f used in each layer, the basis weight per unit area, and the degree of entanglement of the fibers 2f and 3f based on the hydroentangling method.

[0120] In addition, as a method of making the average narrow width of the non-skin side region Qd in the narrow width evaluation test narrower than the average narrow width of the skin side region Qu in the narrow width evaluation test, it is not limited to this. For example, the thickness (fiber diameter) of the fibers in the non-skin side region Qd can be made thinner than the thickness (fiber diameter) of the fibers in the skin side region Qu. Alternatively, it can be that the average narrow width of the non-skin side region Qd in the narrow width evaluation test is made narrower than the average narrow width of the skin side region Qu in the narrow width evaluation test by using latent crimped fibers having a stronger crimping property for the fibers used in the non-skin side region Qd than for the fibers used in the skin side region Qu.

[0121] In addition, preferably, in the void ratio evaluation test for quantitatively evaluating the ratio of voids in a predetermined area (measurement area Y), the ratio of voids in the non-skin side area Qd is smaller than the ratio of voids in the skin side area Qu in the void ratio evaluation test. The void ratio evaluation test will be described later. Thus, when the sanitary napkin 1 (absorbent layer 10) absorbs excrement, it is easy to introduce the excrement from the skin side area Qu to the non-skin side area Qd with a smaller ratio of voids by capillary action, and it is easy to promote the diffusion of excrement in the non-skin side area Qd. In addition, in the worn state, it is easy to reduce the excrement staying in the skin side area Qu, so that the discomfort caused by the contact between the excrement and the wearer's skin can be reduced.

[0122] In the sanitary napkin 1 of the present embodiment, as described above, each non-woven fabric sheet of the skin side layer 2 and the non-skin side layer 3 is formed by the spunlace method. By pouring water from the skin side toward the non-skin side, the fibers 2f and 3f are pressed from the skin side toward the non-skin side. Therefore, the ratio of voids in the non-skin side area Qd in the void ratio evaluation test is smaller than the ratio of voids in the skin side area Qu in the void ratio evaluation test. In addition, the method for making the ratio of voids in the non-skin side area Qd in the void ratio evaluation test smaller than the ratio of voids in the skin side area Qu in the void ratio evaluation test is not limited to this. For example, the fiber thickness (fiber diameter) of the non-skin side area Qd may be made thinner than the fiber thickness (fiber diameter) of the skin side area Ru. In addition, it may be that the ratio of voids in the non-skin side area Rd in the void ratio evaluation test is made smaller than the ratio of voids in the skin side area Ru in the void ratio evaluation test by using latent crimped fibers having a stronger crimping property than the fibers used for the skin side area Ru for the fibers of the non-skin side area Rd.

[0123] <Width evaluation test method and void ratio evaluation test method>

[0124] The width evaluation test and the void ratio evaluation test can be carried out by the following methods.

[0125] First, X-ray CT measurement is performed on the absorbent layer 10. Using a high-resolution 3D X-ray microscope nano3DX manufactured by Rigaku Corporation, non-destructive tomography (CT measurement) is carried out under the following conditions.

[0126] X-ray source: Cu

[0127] Tube voltage - tube current: 40 kV - 30 mA

[0128] Detector: sCMOS camera (lens: 1080)

[0129] Resolution: 2.51 μm / voxel

[0130] A measurement region (predetermined region) Y of the absorbent layer 10 is randomly extracted from the three-dimensional data obtained by photographing, and the voids are analyzed. In addition, the measurement region Y for this analysis is a rectangular parallelepiped (which may be a cube) within an arbitrary range in the plane direction of the absorbent layer 10 and having a length in the thickness direction equal to the thickness H10 of the absorbent layer 10.

[0131] In the present embodiment, as Figure 8 shown, when the measurement region Y is divided into three equal parts in the thickness direction, the lowermost side is set as the first region Y1, the uppermost side is set as the third region Y3, and the region between the first region Y1 and the third region Y3 is set as the second region Y2. Figure 8 FIG. is a diagram for explaining the measurement region Y. The fibers 2f and 3f are colored (gray) portions, the voids are colored (white) portions, and the lattice portion represents the range of the measurement region randomly extracted from the absorbent layer 10. The first region Y1 is the skin side region Qu of the absorbent layer 10 (a part of the skin side region Qu when observed in the thickness direction), the second region Y2 is the intermediate region Qm of the absorbent layer 10 (a part of the intermediate region Qm when observed in the thickness direction), and the third region Y3 is the non-skin side region Qd of the absorbent layer 10 (a part of the non-skin side region Qd when observed in the thickness direction).

[0132] The tomographic image obtained by X-ray CT becomes an image in which low-density (void) components that are easily penetrated by X-rays are represented by black, and high-density (fiber) components that easily absorb X-rays are represented by white. Based on this image, the void ratio and the average narrowness of the voids in each of the regions Y1 to Y3 are calculated.

[0133] The void ratio of each of the regions Y1 to Y3 can be calculated by obtaining the volume of the voids in each of the regions Y1 to Y3 and the volume of the measurement region Y based on the tomographic image obtained by X-ray CT. For example, the void ratio of the first region Y1 is as follows.

[0134] Void ratio of the first region Y1 = (Volume of the voids in the first region Y1) / (Volume of the first region Y1)

[0135] In addition, the volume of the first region Y1 is the sum of the volume of the fibers in the first region Y1 and the volume of the voids in the first region Y1.

[0136] For the narrowness of the gaps in each of the regions Y1 to Y3, the Thickness of "A new method for the model-independent assessment of thickness in three-dimensional images" (by T. HILDEBRAND & P. RUEGSEGGER, Journal of Microscopy, Vol. 185, Pt1, January 1997, pp. 67 - 75) is applied to the spatial part and the distribution of the narrowness of the gaps and the average narrowness of the gaps are calculated based on the results of the narrowness of a part of the volume (gaps). That is to say, the "Thickness" in the definition of the above-mentioned literature corresponds to the "narrowness of the gaps" in the skin-side layer 2 (each of the regions Y1 to Y3), and by specifying the narrowness in each part corresponding to the volume part of the gaps in the tomographic image obtained by X-ray CT, the distribution of the narrowness of the gaps and the average narrowness of the gaps can be obtained.

[0137] An outline of a method for quantitatively evaluating the narrowness of the gaps (such as gap Z) inside each of the analyzed regions Y1 to Y3 will be described. Figure 9 It is a diagram for explaining an outline of a method for evaluating the narrowness in gap Z. For example, as Figure 9 shown, at arbitrary points P1 to P4 inside gap Z, spheres with the largest size within the regions containing each of these points are respectively assumed, and the process of obtaining the diameters D1 to D4 of each of these spheres is carried out. In addition, Figure 9 describes the process of obtaining the diameters D1 to D4 of the spheres at the 4 points (points P1 to P4), but in the actual quantitative evaluation of the narrowness of the gaps, the following process is carried out: the process of obtaining the diameters D of the spheres at multiple points P inside gap Z. Such a process is carried out for all points within each of the regions Y1 to Y3, the distribution of the obtained diameters is calculated, and the average value is obtained. Thus, the average narrowness of the gaps in each of the regions Y1 to Y3 can be quantitatively evaluated.

[0138] In addition, preferably, the hydrophilicity of the skin-side region Qu is lower than the hydrophilicity of the non-skin-side region Qd. As Figure 5 shown in A, the skin-side layer 2 of the present embodiment includes an upper layer 2A mostly formed of hydrophobic fibers 2fa and a lower layer 2B mostly formed of hydrophilic fibers 2fb. As Figure 5As shown in FIG. B, the non-skin side layer 3 is formed of hydrophilic fibers 3f. That is, in the absorbent layer 10 where the skin side layer 2 and the non-skin side layer 3 overlap each other, the hydrophilicity of the non-skin side region Qd (the fibers 2fb of the lower layer 2B and the fibers 3f of the non-skin side layer 3 located on the non-skin side of the upper layer 2A) is higher than the hydrophilicity of the skin side region Qu (the fibers 2fa in the upper layer 2A) closest to the skin side. Thus, the concern that the excrement absorbed by the skin side region Qu in the worn state stays in the skin side region Qu can be reduced, and it becomes easy to introduce the excrement toward the non-skin side region Qd. In addition, it becomes easy to spread the excrement that has reached the non-skin side region Qd within the non-skin side region Qd, and the concern that the excrement returns from the non-skin side region Qd to the skin side region Qu can be reduced. Therefore, the concern that the excrement stays in the skin side region Qu and continuously contacts the wearer's skin can be reduced.

[0139] The hydrophilicity of each region is judged based on the contact angle with water. The measurement of the contact angle of each region with water can be carried out using the following method.

[0140] First, cut out a quadrilateral shape with a length of 150 mm in the length direction and a width of 70 mm in the width direction from the region to be measured as a measurement sample (in the case where it is difficult to cut out, as long as the maximum length and the maximum width are within the measurable range, they are not limited to the exemplified values). Then, attach a droplet of ion-exchanged water to the measurement surface of the contact angle in each measurement sample, record the droplet, and measure the contact angle based on the recorded image. More specifically, as the measurement device, use a microscope VHX-1000 manufactured by KEYENCE CORPORATION, and install a medium magnification zoom lens in an inverted state at 90° to the measurement device. Place each measurement sample on the measurement stage of the measurement device in a state where the measurement surface faces upward and can be observed from the width direction of each measurement sample. Then, attach a 3 μL droplet of ion-exchanged water to the measurement surface of each measurement sample placed on the measurement stage, record the image of the droplet, and input it to the measurement device. Among the multiple recorded images, select 10 images where the two ends or one end in the width direction of the droplet are clear, measure the contact angle of the droplet for each of the 10 images, and set the average value of their contact angles as the contact angle of the region (fiber layer) to be measured. The measurement environment is set to 20 °C / 50% RH.

[0141] The smaller the contact angle with water measured by the above method, the higher the hydrophilicity (the lower the hydrophobicity), and the larger the contact angle, the lower the hydrophilicity (the higher the hydrophobicity). If the contact angle is less than 90 degrees, it is hydrophilic, and if the contact angle is 90 degrees or more, it is hydrophobic. That is, in the skin side layer 2, the contact angle of the skin side region Ru side with water is larger than the contact angle of the non-skin side region Rd with water.

[0142] In the absorbent layer 10 of the present embodiment, the fiber 2fa as a hydrophobic fiber is provided at the position closest to the skin side in the thickness direction (the upper layer 2A of the skin-side layer 2), and the fibers 2fb and 3f as hydrophilic fibers are provided at a position closer to the non-skin side than the upper layer 2A. Thus, the hydrophilicity of the skin-side region Qu is lower than that of the non-skin side region Qd, but it is not limited thereto. For example, the entire region of the non-woven fabric sheet of the absorbent layer 10 (the skin-side region Qu, the intermediate region Qm, and the non-skin side region Qd) is formed entirely of the fibers 2f and 3f with a constant hydrophilicity, and a water repellent can be applied to the skin-side region Qu of the absorbent layer 10 (two non-woven fabric sheets), or a hydrophilic agent can be applied to the non-skin side region Qd of the absorbent layer 10 (two non-woven fabric sheets).

[0143] In addition, preferably, the basis weight per unit area of the fibers 2f and 3f of the absorbent layer 10 is 80 gsm or more and 350 gsm or less. Compared with the case where the basis weight per unit area of the fibers 2f and 3f of the absorbent layer 10 is less than 80 gsm, by setting the basis weight per unit area of the fibers 2f and 3f of the absorbent layer 10 to 80 gsm or more, it is easier to improve the skin feel, easier to ensure the absorbency and liquid retention of excrement, and easier to absorb excrement. In addition, compared with the case where the basis weight per unit area of the fibers 2f and 3f of the absorbent layer 10 is greater than 350 gsm, by setting the basis weight per unit area of the fibers 2f and 3f of the absorbent layer 10 to 350 gsm or less, it is possible to reduce the discomfort during wearing caused by the absorbent layer 10 becoming too thick or the stiffness of the absorbent layer 10 becoming too high.

[0144] Moreover, the absorbent layer 10 has a desired absorption function. The absorption function of the absorbent layer 10 can be measured by the following absorption test.

[0145] <Measurement method of absorption function>

[0146] (1) First, take out the absorbent layer 10 (the skin-side layer 2 and the non-skin side layer 3) from the sanitary napkin 1.

[0147] (2) Next, observe the sanitary napkin 1 in the thickness direction, set the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 as a predetermined region, and cut out this predetermined region as a sample. In the sanitary napkin 1 of the present embodiment, the sample has a size of 70 mm × 70 mm.

[0148] (3) Then, measure the pre-absorption weight a of the sample as the weight of the sample using a balance with a sensitivity of 0.01 g. The pre-absorption weight a is the weight of the sample before absorbing distilled water.

[0149] (4) Next, clamp one end of the sample with a fixture, and set the front end of the fixture and the sample to a state perpendicular in the longitudinal direction.

[0150] Immerse the sample together with the fixture in a water tank filled with distilled water (or deionized water) at 23 ± 1°C. At this time, make the skin side of the absorbent layer 10 face upward. Gently press the sample towards the water, and keep the sample completely immersed in the distilled water for 60 seconds.

[0151] (5) After that, lift the fixture, lift the sample from the distilled water, and while the sample is completely out of the water surface of the water tank, clamp the sample with the fixture and hang the sample from the fixture for 90 seconds.

[0152] (6) After that, weigh the sample excluding the fixture to obtain the absorbed weight A as the weight of the sample after absorption.

[0153] (7) Then, the value obtained by subtracting the weight a before absorption from the absorbed weight A is the absorbed weight b.

[0154] (Absorbed weight b) = (Absorbed weight A) - (Weight a before absorption)

[0155] Preferably, the value obtained by dividing the obtained absorbed weight b by the weight a before absorption is 5 or more.

[0156] Absorbed weight b ÷ Weight a before absorption ≥ 5

[0157] Perform the above (1) to (7) for 5 samples respectively, and set the average value of the results of the 5 samples as the measurement result.

[0158] Figure 10 It is a graph showing the measurement results of the absorption test of the absorbent layer 10. Figure 10 The numbers 1 to 3 in it are the average values of the results of 5 samples. As Figure 10 shown, in the absorbent layer 10 of the sanitary napkin 1 in the present embodiment, the value obtained by dividing the weight of the distilled water absorbed (absorbed weight b) by the weight of a predetermined area before absorbing the distilled water is greater than 7 respectively. That is to say, the value obtained by dividing the absorbed weight b by the weight a before absorption is clearly 5 or more. Therefore, the absorbent layer 10 of the sanitary napkin 1 has a sufficient absorption capacity for absorbing excreta and can reduce the concern of excreta leakage from the sanitary napkin 1.

[0159] The larger the value obtained by dividing the absorption weight b by the weight a before absorption, the more the absorption layer 10 can absorb distilled water, and thus the more excrement it can absorb. Compared with the case where the value obtained by dividing the absorption weight b by the weight a before absorption is less than 5, by setting the value obtained by dividing the absorption weight b by the weight a before absorption to 5 or more, the sanitary napkin 1 having the absorption layer 10 can sufficiently ensure the function of absorbing liquid. In addition, the absorbed liquid can be retained within the absorption layer 10. In this way, the absorption layer 10 has an absorption function to the extent of absorbing excrement, and can diffuse and retain the absorbed excrement within the absorption layer 10.

[0160] Preferably, the bending stiffness B based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorption layer 10 in the sanitary napkin 1 is 1.2 gf·cm 2 / cm or less. In the present embodiment, the central portion in the length direction of the absorption layer 10 is the crotch region, and the central portion in the length direction and the central portion in the width direction are also the excrement discharge port contact regions during wearing. Generally, the larger the value of the bending stiffness B, the stronger the bending resistance. Compared with the case where the bending stiffness B of the central portion in the length direction and the central portion in the width direction of the absorption layer 10 is greater than 1.2 gf·cm 2 / cm, by setting the bending stiffness B based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorption layer 10 to 1.2 gf·cm 2 / cm or less, the absorption layer 10 can be made softer, and it is easy to make the sanitary napkin 1 using the absorption layer 10 softer. Therefore, in the wearing state, the sanitary napkin 1 can easily follow the shape and movement of the wearer's body, can reduce the discomfort caused to the wearer, and can improve the comfort in the wearing state.

[0161] <Measurement method of bending stiffness B>

[0162] The bending stiffness B (gf·cm 2 / cm) at the central portion in the length direction and the central portion in the width direction of the absorption layer 10 can be measured by a known method. For example, the value of the bending stiffness B (gf·cm 2 / cm) can be measured using a KES-FB2-L large bending measurement test machine manufactured by Kato Tech Co., Ltd. First, the absorption layer 10 (skin side layer 2 and non-skin side layer 3) is taken out from the sanitary napkin 1, and a 50 mm×50 mm portion at the central portion in the length direction and the central portion in the width direction of the absorption layer 10 is cut out as a sample. In this sample, it is fixed between the chucks of the measurement test machine in such a way that it can be measured by bending along the length direction of the absorption layer 10. It is bent to the front side to a maximum curvature of +0.5 cm -1 , and then, it is bent to the back side to a maximum curvature of -0.5 cm-1 , and then restored, thereby performing the measurement. The bending stiffness value B (gf·cm 2 / cm) is calculated based on the average value of the slopes of the bending moments with respect to the curvatures of 0.1 to 0.3 for bending toward the front side and the slopes with respect to the curvatures of -0.1 to -0.3 for bending toward the back side.

[0163] Figure 11 A is a graph showing the measurement results of the bending characteristics based on the KES method. Figure 11 A shows the measurement results of the bending characteristics based on the KES method of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment and the absorbent body (absorbent layer) of the comparative product X which is an existing sanitary napkin.

[0164] The comparative product X is a well-known structure in the past and is a sanitary napkin having a structure including a topsheet, an absorbent body, and a backsheet in this order from the skin side. The topsheet of the comparative product X is such a sheet member: it has excellent liquid permeability, and on the other hand, it is not easy to absorb or retain liquid. The absorbent body of the comparative product X is a polymer foam structure capable of absorbing and retaining liquid. The backsheet of the comparative product X is a liquid-impermeable sheet member. The topsheet of this comparative product X allows liquid to pass through, and on the other hand, it is not easy to absorb or retain liquid. Therefore, it is judged that the absorbent layer of the comparative product X is only the absorbent body. The absorbent body was taken out from the comparative product X, and at the central portion in the length direction and the central portion in the width direction of the comparative product X, in the same manner as the sanitary napkin 1, the measurement of the bending characteristics based on the above KES method was performed.

[0165] As Figure 11 shown in A, the bending stiffness B (gf·cm 2 / cm) at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment is 0.1008 gf·cm 2 / cm to 1.1017 gf·cm 2 / cm, and is 1.2 gf·cm 2 / cm or less. In contrast, the bending stiffness B (gf·cm 2 / cm) at the central portion in the length direction and the central portion in the width direction of the absorbent body of the comparative product X is 0.5493 gf·cm 2 / cm to 6.1168 gf·cm 2 . In addition, the average value (0.5390 gf·cm 2 / cm) of the measurement results of the bending stiffness B of the absorbent layer 10 of the sanitary napkin 1 is less than the average value (2.5294 gf·cm 2 / cm). According to this result, for the absorbent layer 10 of the sanitary napkin 1, the absorbent layer 10 is softer than the absorbent body of the comparative product X, so that the sanitary napkin 1 can be softer than the comparative product X. Thus, for the sanitary napkin 1, compared with the comparative product X, in the wearing state, the sanitary napkin 1 is easy to follow the shape and movement of the wearer's body, can reduce the discomfort brought to the wearer, and can improve the comfort in the wearing state.

[0166] Preferably, the bending hysteresis 2HB based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 in the sanitary napkin 1 is 0.93 gf·cm 2 / cm or less. The 2HB value is the bending recovery property, and the larger the value of the bending hysteresis 2HB, the worse the recovery property. Compared with the case where the bending hysteresis 2HB based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 is greater than 0.93 gf·cm 2 / cm, by setting the bending hysteresis 2HB based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 to 0.93 gf·cm 2 / cm or less, it is easy to make the absorbent layer 10 deformed due to external forces or the like in the wearing state return to its original shape, and the discomfort and unhappiness brought to the wearer due to the deformation of the absorbent layer 10 can be reduced.

[0167] <Method for Measuring Bending Hysteresis 2HB>

[0168] The bending hysteresis 2HB (bending recovery property) can be measured by a known method. For example, it can be measured using an automated bending tester (KES-FB2-L) manufactured by Kato Tech Co., Ltd.

[0169] First, take out the absorbent layer 10 (skin side layer 2 and non-skin side layer 3) from the sanitary napkin 1, and cut out a 50 mm × 50 mm sized portion at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 as a sample.

[0170] Next, hold both ends of the sample in the length direction using a chuck. Then, bend the sample in both positive and negative directions at a curvature change speed of 0.1 cm-1 / min within a range where the curvature is 0.5 cm-1 on the positive side and 0.5 cm-1 on the negative side to obtain a hysteresis curve of the bending moment required for bending in each direction. The bending hysteresis of the bending moment when the curvature is 0.1 cm-1 is defined as the bending hysteresis 2HB.

[0171] Similar to the bending stiffness B, in Figure 11The measurement results of the bending hysteresis 2HB (gf·cm 2 / cm) of the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 of the sanitary napkin 1 according to the present embodiment are shown in [A], and the measurement results of the bending hysteresis 2HB (gf·cm 2 / cm) of the central portion in the length direction and the central portion in the width direction of the absorbent body of the comparative product X are shown.

[0172] As Figure 11 shown in [A], the bending hysteresis 2HB (gf·cm 2 / cm) of the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 of the sanitary napkin 1 according to the present embodiment is 0.8204 gf·cm 2 / cm to 0.9253 gf·cm 2 / cm, and thus is 0.93 gf·cm 2 / cm or less. In contrast, the bending hysteresis 2HB (gf·cm 2 / cm) of the central portion in the length direction and the central portion in the width direction of the absorbent body of the comparative product X is 4.0183 gf·cm 2 / cm to 4.8341 gf·cm 2 / cm, which is significantly larger than 0.93 gf·cm 2 / cm. Based on this result, for the sanitary napkin 1, compared with the comparative product, even when the absorbent layer 10 is deformed due to external forces such as the shape of the wearer's body and the movement of the wearer during the wearing state, it is easy to restore the absorbent layer 10 to its original shape, and the discomfort and unpleasantness caused to the wearer due to the deformation of the absorbent layer 10 can be reduced.

[0173] Preferably, the linearity LC (compression hardness) of the compression characteristics based on the KES method of the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 in the sanitary napkin 1 is 0.6 or more. The larger the value of the linearity LC (compression hardness) of the compression characteristics, the stronger the compression resistance. Compared with the case where the linearity LC (compression hardness) of the compression characteristics is less than 0.6, by setting the linearity LC (compression hardness) of the compression characteristics to 0.6 or more, the deformation of the absorbent layer 10 can be reduced, and thus the discomfort caused to the wearer in the wearing state due to the deformation of the absorbent layer 10 can be reduced. In addition, the concern that the absorbent layer 10 is deformed and excrement leaks from the absorbent layer 10 can be reduced.

[0174] In addition, preferably, the compression resilience RC (compression recovery) based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 in the sanitary napkin 1 is 38.0% or more. The closer the value of the compression resilience RC (compression recovery) is to 100%, the higher the recovery property. Even when a force is applied to the sanitary napkin 1 in the worn state and the absorbent layer 10 is deformed, compared with the case where the compression resilience RC (compression recovery) based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 is less than 38.0%, by setting the compression resilience RC (compression recovery) based on the KES method at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 to 38.0% or more, it is easier for the shape of the absorbent layer 10 to be restored, and thus the discomfort caused by the deformation of the absorbent layer 10 to the wearer in the worn state can be reduced.

[0175] <Method for Measuring Linearity LC and Compression Resilience RC of Compression Characteristics>

[0176] The linearity LC (compression hardness) and compression resilience RC (compression recovery) of the compression characteristics can be measured by a known method. For example, they can be measured using an automated compression testing machine KES-FB3 AUTO-A manufactured by Kato Tech Co., Ltd.

[0177] First, the absorbent layer 10 (skin-side layer 2 and non-skin-side layer 3) is taken out from the sanitary napkin 1, and a 50 mm × 50 mm portion at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 is cut out as a sample.

[0178] For a predetermined area, each sample is compressed between steel plates with circular planar terminals having an area of 200 mm 2 The compression speed is set to 50 sec / mm and the maximum compression load is set to 50 gf / cm 2 , and the compression characteristics of the sample are measured.

[0179] For the recovery process, the compression characteristics are also measured at the same speed, and the linearity LC and compression recovery rate RC [%] of the compression characteristic curve obtained from the measurement are calculated.

[0180] Figure 11 Figure B shows the measurement results of the compression characteristics based on the KES method of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment and the absorbent body (absorbent layer) of a comparative product X which is an existing sanitary napkin. In addition, the comparative product X is the same as the product for which the bending characteristics based on the KES method were measured above. Figure 11 Figure B shows the measurement results of the compression characteristics based on the KES method of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment and the absorbent body (absorbent layer) of a comparative product X which is an existing sanitary napkin. In addition, the comparative product X is the same as the product for which the bending characteristics based on the KES method were measured above.

[0181] AsFigure 11 As shown in FIG. B, the linearity LC of the compression characteristics at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment is 0.609 to 0.653, and thus is 0.6 or more. In contrast, the linearity LC of the compression characteristics at the central portion in the length direction and the central portion in the width direction of the absorbent body of the comparative product X is 0.365 to 0.757. In addition, the average value of the linearity LC of the compression characteristics at the central portion in the length direction and the central portion in the width direction of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment is 0.632. In contrast, the linearity LC of the compression characteristics at the central portion in the length direction and the central portion in the width direction of the absorbent body of the comparative product X is 0.575. According to this result, for the absorbent layer 10 of the sanitary napkin 1, compared with the absorbent body of the comparative product X, deformation can be reduced, and the discomfort caused by the deformation of the absorbent layer 10 to the wearer in the wearing state can be reduced. In addition, for the absorbent layer 10 of the sanitary napkin 1, compared with the absorbent body of the comparative product X, leakage of excrement caused by the deformation of the absorbent layer 10 can be reduced.

[0182] For the compression resilience RC, as also Figure 11 As shown in FIG. B, the compression resilience RC of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment at the central portion in the length direction and the central portion in the width direction is 38.80% to 40.18%, which is significantly greater than 38%. In contrast, the compression resilience RC of the absorbent body of the comparative product X at the central portion in the length direction and the central portion in the width direction is 41.50% to 59.216%. That is, the absorbent layer 10 of the sanitary napkin 1 of the present embodiment has the characteristic of having a compression resilience RC equivalent to that of the comparative product X. Thus, it is easy to restore the shape of the absorbent layer 10, the discomfort caused by the deformation of the absorbent layer 10 in the wearing state can be reduced, and the air permeability can be improved. Therefore, the comfort in the wearing state can be improved.

[0183] Furthermore, preferably, in the elongation test for measuring the magnitude of the force for elongating the absorbent layer 10 (skin-side layer 2 and non-skin-side layer 3) by a predetermined length, the value obtained by dividing the value of the magnitude of the force measured in the 10th elongation test of the absorbent layer 10 by the value of the magnitude of the force measured in the 1st elongation test of the absorbent layer 10 is 50% or more. Compared with the case where the value obtained by dividing the value of the magnitude of the force measured in the 10th elongation test by the value of the magnitude of the force measured in the 1st elongation test is less than 50%, since the value obtained by dividing the value of the magnitude of the force measured in the 10th elongation test by the value of the magnitude of the force measured in the 1st elongation test is 50% or more, even in the worn state, breakage of the absorbent layer 10 can be reduced, and even when a force is repeatedly applied to the absorbent layer 10 to elongate it, a predetermined stress can be maintained. Therefore, the sanitary napkin 1 having the absorbent layer 10 can easily follow the shape and movement of the wearer's body. That is to say, for the sanitary napkin 1 having such an absorbent layer 10, it is possible to form such a sanitary napkin 1 that in a state where a force is applied to the absorbent layer 10 from the outside in the worn state, the absorbent layer 10 is not easily broken, and the absorbent layer 10 easily adapts to the shape and movement of the wearer's body.

[0184] <Measurement method of elongation test>

[0185] The elongation test can be measured by a cyclic test using an AUTOGRAPH tensile testing machine manufactured by Shimadzu Corporation, for example, model AG-1KNI. The specific measurement method is as follows.

[0186] First, the absorbent layer 10 (skin-side layer 2 and non-skin-side layer 3) as the measurement target area is taken out from the sanitary napkin 1 to be the object, and a specimen is prepared. For the cut specimen, the absorbent layer 10 is fixed to the chuck of the testing machine with a chuck distance of 100 mm. Next, the specimen is elongated in the longitudinal direction at a speed of 100 mm / minute to 130% of the chuck distance of 100 mm, that is, the chuck distance of 130 mm, and then returned to the position of the chuck distance of 100 mm at a speed of 100 mm / minute. The maximum value of the magnitude of the force (N) at this time is set as the measurement result value of the 1st elongation test (the value of the magnitude of the force measured in the 1st measurement).

[0187] Next, the material in the state of a chuck distance of 100 mm is elongated in the longitudinal direction at a speed of 100 mm / minute to 130% of the chuck distance of 100 mm, that is, the chuck distance of 130 mm, and then returned to the position of the chuck distance of 100 mm at a speed of 100 mm / minute. The maximum value of the magnitude of the force (N) at this time is set as the measurement result value of the 2nd elongation test (the value of the magnitude of the force measured in the 2nd measurement). The elongation test is carried out in the same way to obtain the measurement result values of the 3rd to 10th times.

[0188] Then, calculate the value obtained by dividing the measured result value of the 10th measurement (the value of the magnitude of the force measured in the 10th measurement) by the measured result value of the 1st measurement (the value of the magnitude of the force measured in the 1st measurement).

[0189] Figure 12 It is a graph showing the measurement results of the elongation test of the absorbent layer 10. Figure 12 It shows the measurement results of the elongation test of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment and the absorbent body (absorbent layer) of the comparative product X which is an existing sanitary napkin. In addition, the comparative product X is the same as the product for which the bending characteristics were measured based on the KES method described above.

[0190] The measurement result (magnitude of force) of the elongation test of the sanitary napkin 1 is as Figure 12 shown. The measurement result (magnitude of force) of the 10th elongation test of the absorbent layer 10 of the sanitary napkin 1 is 15.270 N. The value obtained by dividing the value of the magnitude of the force measured in the 10th measurement (15.270 [N]) of the elongation test of the sanitary napkin 1 by the value of the magnitude of the force measured in the 1st measurement (20.967 [N]) is 15.270 [N] / 20.967 [N] = 0.7283, which is clearly 50% or more. In contrast, in the comparative product X, in the 2nd elongation test, the absorbent body broke, and the measurement result of the 10th elongation test could not be obtained. That is, it is 0 N. For the absorbent layer 10 of the sanitary napkin 1, the value is also greater than 0 N in the 10th measurement result. Therefore, even when an external force is applied in the wearing state, breakage and fracture of the absorbent layer 10 can be reduced. Therefore, for the absorbent layer 10 of the sanitary napkin 1 of the present embodiment, compared with the absorbent body of the comparative product X, breakage and fracture of the absorbent layer 10 in the wearing state are less likely to occur. In addition, the value obtained by dividing the value of the magnitude of the force measured in the 10th measurement (15.270 [N]) of the elongation test by the value of the magnitude of the force measured in the 1st measurement is 15.270 [N] / 20.967 [N] = 0.7283, which is clearly 50% or more. Thus, compared with the case where the value obtained by dividing the value of the magnitude of the force measured in the 10th measurement of the elongation test by the value of the magnitude of the force measured in the 1st measurement is less than 50%, the absorbent layer 10 is more likely to adapt to the body and movement of the wearer, and is more likely to bring a comfortable wearing feeling to the wearer.

[0191] In the above-described embodiment, the fibers (latent crimp fibers) 2f and 3f constituting the absorbent layer 10 are set to the same thickness (2.2 dtex) throughout the entire area of each nonwoven fabric, but it is not limited thereto. The thickness (fiber diameter) of the fibers 2f and 3f in the absorbent layer 10 (skin-side layer 2, non-skin-side layer 3) can be selected to be any thickness. For example, when the portion closer to the skin side than the center in the thickness direction of the absorbent layer 10 is set as the first region and the portion closer to the non-skin side than the center in the thickness direction of the absorbent layer 10 is set as the second region, the maximum value of the thickness of the fibers in the first region is larger than the maximum value of the thickness of the fibers in the second region. In a general nonwoven fabric, the coarser the fiber thickness, the easier it is for the voids formed by the plurality of fibers to become larger. Therefore, it is easy to introduce excrement into the second region where the maximum value of the fiber thickness is smaller than that of the fibers in the first region by capillary action, and by facilitating the diffusion of excrement within the second region, the concern that excrement remains on the skin side surface of the first region can be reduced. Thus, since the concern that excrement continuously contacts the wearer's skin during the wearing state can be reduced, the comfort during wearing can be improved.

[0192] In the above-described embodiment, the skin-side layer 2 and the non-skin-side layer 3 that overlap each other in a state of being in contact with each other are set as the absorbent layer 10, but it is not limited thereto. Even when a liquid-permeable sheet member having no liquid absorption function and retention function is sandwiched between the skin-side layer 2 and the non-skin-side layer 3, the absorbent layer 10 can be constituted by the skin-side layer 2 and the non-skin-side layer 3. In addition, the nonwoven fabric containing fibers including latent crimp fibers that constitutes the absorbent layer 10 is not limited to two (skin-side layer 2 and non-skin-side layer 3). The nonwoven fabric containing fibers including latent crimp fibers that constitutes the absorbent layer 10 can be one (only the skin-side layer 2 or only the non-skin-side layer 3), or three or more. Even when the number of nonwoven fabrics containing fibers including latent crimp fibers that constitute the absorbent layer 10 is one or three or more, the structure of the above-described embodiment can be applied.

[0193] Figure 13 It is a diagram for explaining the sanitary napkin 100 which is a modified example of the present embodiment. It can also be as Figure 13 The sanitary napkin 100 shown is a sanitary napkin 100 composed only of the skin-side layer 2 as the absorbent layer 10 (absorbent body) and the backsheet 4. In addition, it may not have the side flaps 5 as in the sanitary napkin 100.

[0194] The skin-side layer 2 of the sanitary napkin 100 is a member that comes into contact with the skin of the wearer and is an absorbent member capable of retaining liquid (excrement) in the voids formed by the fibers 2f. The backsheet 4 is an impermeable sheet as described above.

[0195] The skin-side layer 2 (absorbent layer 10) of the sanitary napkin 100 is a layer that can absorb and retain liquid. Figure 14 This is a diagram for explaining the skin-side layer 2 of the sanitary napkin 100. The skin-side layer 2 is a non-woven fabric sheet formed of fibers 2f that are only latent crimped fibers (100% latent crimped fibers). The skin-side layer 2 has voids formed by a plurality of fibers 2f. In this skin-side layer 2, the value obtained by dividing the weight of the latent crimped fibers by the weight of the plurality of fibers 2f is 70% or more.

[0196] In the skin-side layer 2, excreta can be absorbed and retained by the voids formed by the plurality of fibers 2f, and the air permeability can be improved by the voids formed by the fibers 2f. By improving the air permeability of the skin-side layer 2, it is possible to reduce discomfort such as stuffiness felt by the wearer of the sanitary napkin 1 in the wearing state. In addition, in the skin-side layer 2, compared with the case where the value obtained by dividing the weight of the latent crimped fibers by the weight of the plurality of fibers 2f is less than 70%, since the value obtained by dividing the weight of the latent crimped fibers by the weight of the plurality of fibers 2f is 70% or more, it is easy to make the non-woven fabric sheet in the skin-side layer 2 firm and soft and elastic by the crimped fibers. Therefore, loss of elasticity and deformation of the skin-side layer 2 can be reduced. For the sanitary napkin 1 using this skin-side layer 2 as the absorbent layer 10, it is possible to reduce leakage of excreta caused by loss of elasticity and deformation of the skin-side layer 2, or to reduce discomfort and unpleasantness brought to the wearer due to loss of elasticity and deformation of the skin-side layer 2, and the comfort during wearing can be improved. In addition, as in the case of the sanitary napkin 100, when the number of components used is small (the skin-side layer 2 and the backsheet 4), the production cost can be reduced. In addition, by reducing the number of components used, the stiffness of the components, the adhesive for pasting the components, etc. can be reduced, the stiffness of the sanitary napkin becomes low, and the sanitary napkin can be made soft, so the discomfort during wearing can be reduced and the comfort during wearing can be improved.

[0197] Furthermore, it may be that, as Figure 14 shown, when the skin-side layer 2 is trisected in the thickness direction, the region closest to the skin side is set as the skin-side region Ru, the region closest to the non-skin side is set as the non-skin side region Rd, the region between the skin-side region Ru and the non-skin side region Rd is set as the intermediate region Rm, and the hydrophilicity of at least a part of the fibers 2f in the non-skin side region Rd is higher than the hydrophilicity of the fibers 2f in the skin-side region Ru, a part of the fibers 2f in the non-skin side region Rd is exposed on the skin-side surface of the skin-side layer 2. Specifically, it may be that, as Figure 14As shown, in the case where the non-skin-side region of the skin-side layer 2 has hydrophilic fibers 2fb with a hydrophilicity higher than that of the fibers 2f in the skin-side region Ru, there are hydrophilic fibers 2fb on the side of the surface facing the skin surface that are exposed to the skin-side layer 2. The hydrophilic fibers 2fb on the side of the surface facing the skin surface that are exposed to the skin-side layer 2 are liable to introduce the excrement absorbed from the skin surface side toward the non-skin-side region Rd. Therefore, in the skin-side layer 2, it is easy to promote the diffusion of excrement from the skin side toward the non-skin side, and it is easy to promote the diffusion of liquid within the non-skin-side region Rd, which can reduce the concern that excrement remains on the skin side surface of the skin-side region Rd, and can reduce the discomfort caused by the continuous contact of excrement with the wearer's skin, thereby improving the comfort during wearing.

[0198] For this skin-side layer 2, during the formation process of the nonwoven fabric sheet, by performing high-pressure water flow treatment such as water jet in a state where the hydrophobic fibers 2fa in the skin-side region Ru and the hydrophilic fibers 2fb in the non-skin-side region Rd are laminated, the fibers between the respective fiber layers and the fibers between the respective meshes are intertwined (process (d) for forming a nonwoven fabric based on the above-described hydroentangling method). At this time, the water flow passing through the hydrophobic fibers 2fa and the hydrophilic fibers 2fb in this order is reflected by the conveyor belt and goes toward the skin side in the order of the hydrophilic fibers 2fb and the hydrophobic fibers 2fa. Thus, the hydrophilic fibers 2fb are pulled up toward the skin-side region Ru. Thereby, hydrophilic fibers 2fb are provided on the side of the surface facing the skin surface that are exposed to the skin-side layer 2.

[0199] In addition, as a method for providing the hydrophilic fibers 2fb on the side of the surface facing the skin surface that are exposed to the skin-side layer 2, it is not limited thereto. Known methods can be used. For example, after the fibers 2f are intertwined using the hydroentangling method, the hydrophilic fibers 2fb can be exposed to the side of the surface facing the skin surface of the skin-side layer 2 using the needling method.

[0200] The sanitary napkin 100 with the skin-side layer 2 as the absorbent body (absorbent layer 10) of the present invention is formed as an absorbent article composed of the skin-side layer 2 and the backsheet 4, but it is not limited thereto. Even when the skin-side layer 2 is the absorbent layer 10, it can be formed as an absorbent article combined with any components. For example, when the skin-side layer 2, the non-skin-side layer 3, and the backsheet 4 are provided, the non-skin-side layer 3 can also be a component that does not have the functions of liquid absorption and retention, or an additional sheet component that does not have the liquid absorption function can be arranged at a position closer to the non-skin side than the backsheet 4. In addition, when the absorbent article with the skin-side layer 2 as the absorbent body (absorbent layer 10) of the present invention and the skin-side layer 2 and the non-skin-side layer 3 are the absorbent body (absorbent layer 10) of the present invention, it can also be a structure having other sheet components (for example, a liquid-permeable topsheet) at a position closer to the skin side than the skin-side layer 2.

[0201] Similarly, it may also be a sanitary napkin (not shown) composed only of the non-skin side layer 3 as the absorbent layer 10 (absorbent body) and the backsheet 4. Further, in the case of having the skin side layer 2, the non-skin side layer 3, and the backsheet 4, the skin side layer 2 may also be a member that does not have the functions of liquid absorption and retention.

[0202] Furthermore, the sanitary napkin for menstruation may also be a sanitary napkin (not shown) that does not have the backsheet 4 and is formed by the absorbent layer 10 including only the skin side layer 2 (or the non-skin side layer 3). For example, it may also be a sanitary napkin in which the non-skin side surface of the skin side layer 2 (non-skin side layer 3) is subjected to waterproof processing. By making it a sanitary napkin formed only by the skin side layer 2 (or the non-skin side layer 3), the number of components can be reduced. In this way, by reducing the number of components used, the production cost can be reduced, or the stiffness of the components, the adhesive for pasting the components, etc. can be reduced, the stiffness of the sanitary napkin can be lowered, so that the sanitary napkin becomes softer, and thus the discomfort during wearing can be reduced and the comfort during wearing can be improved.

[0203] ====Other Embodiments====

[0204] The above-described embodiments are for easy understanding of the present invention and are not used to limitatively interpret the present invention. The present invention can be changed and improved without departing from its gist, and it goes without saying that the present invention includes its equivalents.

[0205] Explanation of Reference Numerals

[0206] 1. Sanitary napkin (sanitary napkin for menstruation, absorbent article); 1w. Wing part; 2. Skin side layer (absorbent body); 2f. Potential shrinkage fiber (fiber); 3. Non-skin side layer (absorbent body); 3f. Potential shrinkage fiber (fiber); 4. Backsheet (outer layer); 5. Side piece; 10. Absorbent layer (absorbent body); 20. Compression part; DH. High-density part; DL. Low-density part; Ru. Skin side area; Rm. Intermediate area; Qd. Non-skin side area; Qu. Skin side area; Qm. Intermediate area; Qd. Non-skin side area.

Claims

1. An absorbent body for an absorbent article, characterized in that: The absorbent body is composed of at least one nonwoven fabric having a plurality of fibers including latent crimping fibers. The absorbent body has voids formed by the plurality of fibers. A value obtained by dividing the weight of the potentially crimped fibers by the weight of the plurality of fibers is 70% or more.

2. The absorbent body according to claim 1, wherein The air permeability resistance value of the absorbent body is 0.32 kPa·s / m or less.

3. The absorbent body according to claim 1 or 2, characterized in that The plurality of fibers are not fused to each other.

4. The absorbent body according to claim 1 or 2, characterized in that The absorbent body has a thickness direction, The absorbent body has voids formed by the plurality of fibers. When the absorbent body is divided into three equal parts along the thickness direction, the area closest to the skin side is defined as the skin side area, the area closest to the non-skin side is defined as the non-skin side area, and the area between the skin side area and the non-skin side area is defined as the intermediate area, The average narrowness of the non-skin side region in a narrowness evaluation test for quantitatively evaluating the narrowness of the space is smaller than the average narrowness of the skin side region in the narrowness evaluation test.

5. The absorbent body according to claim 1 or 2, characterized in that The absorbent body has a thickness direction, The absorbent body has voids formed by the plurality of fibers. When the absorbent body is divided into three equal parts along the thickness direction, the area closest to the skin side is defined as the skin side area, the area closest to the non-skin side is defined as the non-skin side area, and the area between the skin side area and the non-skin side area is defined as the intermediate area, The void ratio of the non-skin side region in a void ratio evaluation test for quantitatively evaluating the void ratio in a predetermined region is smaller than the void ratio of the skin side region in the void ratio evaluation test.

6. The absorbent body according to claim 1 or 2, characterized in that The absorbent body has a thickness direction, The absorbent body has voids formed by the plurality of fibers. When the absorbent body is divided into three equal parts along the thickness direction, the area closest to the skin side is defined as the skin side area, the area closest to the non-skin side is defined as the non-skin side area, and the area between the skin side area and the non-skin side area is defined as the intermediate area, The hydrophilicity of the skin-side region is lower than that of the non-skin-side region.

7. The absorbent body according to claim 1 or 2, characterized in that The absorbent body has a thickness direction, The absorbent body has voids formed by the plurality of fibers. When the absorbent body is divided into three equal parts along the thickness direction, the area closest to the skin side is defined as the skin side area, the area closest to the non-skin side is defined as the non-skin side area, and the area between the skin side area and the non-skin side area is defined as the intermediate area, The hydrophilicity of at least a portion of the fibers in the non-skin side region is higher than that of the fibers in the skin side region. A portion of the fibers in the non-skin-side region is exposed to the skin-side surface of the absorbent body.

8. The absorber according to claim 1 or 2, characterized in that the absorber has a thickness direction, when a part closer to the skin side than the center in the thickness direction of the absorber is defined as the first region and a part closer to the non-skin side than the center in the thickness direction of the absorber is defined as the second region, the maximum value of the fiber thickness in the first region is greater than the maximum value of the fiber thickness in the second region.

9. The absorber according to claim 1 or 2, characterized in that the weight per unit area of the plurality of fibers of the absorber is 80 gsm or more and 350 gsm or less.

10. The absorber according to claim 1 or 2, characterized in that the absorber has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, The bending stiffness B in the Kawabata Evaluation System (KES) of the central portion in the longitudinal direction and the central portion in the width direction of the absorber is 1.2 gf·cm 2 / cm or less.

11. The absorber according to claim 1 or 2, characterized in that the absorber has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, The bending hysteresis 2HB in the KES method at the central portion in the longitudinal direction of the absorber and also at the central portion in the width direction is 0.93 gf·cm 2 / cm or less.

12. The absorber according to claim 1 or 2, characterized in that the absorber has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, the linearity LC of the compression characteristics in the KES method at the central part in the length direction and the central part in the width direction of the absorber is 0.6 or more.

13. The absorber according to claim 1 or 2, characterized in that the absorber has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, the compression resilience RC in the KES method at the central part in the length direction and the central part in the width direction of the absorber is 38.0% or more.

14. The absorber according to claim 1 or 2, characterized in that in an elongation test for measuring the magnitude of the force required to elongate the length in the length direction of the absorber to 1.3 times the length in the length direction of the absorber, the value obtained by dividing the magnitude of the force measured in the 10th measurement of the elongation test of the absorber by the magnitude of the force measured in the 1st measurement of the elongation test of the absorber is 50% or more.

15. An absorbent article comprising the absorber according to claim 1 or 2, characterized in that it has a length direction, a width direction, and a thickness direction, the length in the length direction of the absorber is longer than the length in the width direction, when observing along the thickness direction, the central part in the length direction and the central part in the width direction of the absorbent article are defined as a predetermined area, the weight of the predetermined area before absorbing distilled water is defined as the pre-absorption weight, the weight of the predetermined area after immersing the predetermined area in distilled water for 60 seconds, pulling it out of the distilled water, and hanging it for 90 seconds is defined as the post-absorption weight, the value obtained by subtracting the pre-absorption weight from the post-absorption weight is defined as the absorption weight of the distilled water. At this time, The value obtained by dividing the absorption weight by the weight before absorption is 5 or more.

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