Absorbent article

Abstract

This absorbent article (1) is provided with an absorbent layer (10) which is a non-woven fabric having voids formed from a plurality of fibers or a polymer foam having a plurality of voids, and which is characterized in that the weight of the crotch region before distilled water is absorbed is defined as the pre-absorption weight and the weight of the crotch region before distilled water is absorbed is defined as the pre-absorption weight. When the weight of the crotch region after the crotch region is immersed in distilled water for 60 seconds and then pulled up from the distilled water and suspended for 90 seconds is defined as the post-absorption weight, and the value obtained by subtracting the pre-absorption weight from the post-absorption weight is defined as the absorption weight of the distilled water, the value obtained by dividing the absorption weight by the pre-absorption weight is 5 or more. The absorbent layer (10) is divided into three equal sections in the thickness direction, and the region closest to the skin is defined as a skin-side region, the region closest to the non-skin side is defined as a non-skin-side region, and the space between the skin-side region and the non-skin-side region is defined as an intermediate region. The narrowness of the voids or voids in the non-skin-side region is narrower than the narrowness of the voids or voids in the skin-side region, and the bending hysteresis 2HB in the crotch region in the KES method is 3.5 gfcm2 / cm or less.

Description

Technical Field

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

[0002] Conventionally, absorbent articles such as sanitary napkins, disposable diapers, absorbent pads, etc. 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 absorbent body disposed between the surface sheet and the back sheet. The absorbent body of Patent Document 1 is formed of pulp fibers or the like.

[0003] Prior Art Documents

[0004] Patent Documents

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

[0006] Problems to be Solved by the Invention

[0007] Regarding absorbent articles such as the sanitary napkin of Patent Document 1, as an absorbent article, it is required to have a sufficient liquid absorption amount for excrement in a worn state, and it is required to improve the comfort during wearing, such as improving the followability of the absorbent article to the body shape and movement of the wearer during wearing, and reducing the discomfort after absorbing excrement.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide an absorbent article that improves comfort during wearing.

[0009] Means for Solving the Problems

[0010] The main invention for achieving the above object is an absorbent article which, in an unfolded state, has a longitudinal direction, a width direction, and a thickness direction, and includes an absorbent layer capable of absorbing liquid. The absorbent layer is a non-woven fabric having voids formed by a plurality of fibers or a polymer foam having a plurality of pores. In the crotch region that is located at the wearer's crotch when worn, the weight of the crotch region before absorbing distilled water is defined as the pre-absorption weight, and the weight of the crotch region after immersing the crotch region 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 pre-absorption weight is 5 or more. When the absorbent layer is trisected in the thickness direction, the region closest to the skin side is defined as the skin side region, the region closest to the non-skin side is defined as the non-skin side region, and the region between the skin side region and the non-skin side region is defined as the intermediate region. The narrowness of the voids or pores in the non-skin side region is narrower than the narrowness of the voids or pores in the skin side region. The bending hysteresis 2HB in the KES method of the crotch region is 3.5 gf·cm 2 / cm or less.

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

[0012] Effects of the Invention

[0013] According to the present invention, the comfort during wearing can be improved. Description of the Drawings

[0014] Figure 1 is a top view of the sanitary napkin 1 observed from the skin side.

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

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

[0017] Figure 4 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 is schematically showing Figure 4 a schematic cross-sectional view taken along the line B-B in

[0020] Figure 7 This is a diagram illustrating the sanitary napkin 1 after 30 minutes of dripping horse blood onto it.

[0021] Figure 8 Figure A shows the measurement results of the absorption test for the crotch region M of the sanitary napkin 1. Figure 8 Figure B shows the measurement results of the bending characteristics of the absorbent layer 10 based on the KES method. Figure 8 Figure C shows the measurement results of the compression characteristics of the absorbent layer 10 based on the KES method.

[0022] Figure 9 This is a diagram illustrating the measurement region Y.

[0023] Figure 10 This is a diagram illustrating the outline of the method for evaluating the narrowness in the void Z.

[0024] Figure 11 This is a diagram showing the measurement results of the elongation test of the absorbent layer 10.

[0025] Figure 12 This is a diagram illustrating the sanitary napkin 100 which is a modification of the first embodiment.

[0026] Figure 13 This is a schematic cross-sectional view showing the crotch region M of the skin-side layer 2 of the sanitary napkin 100.

[0027] Figure 14 This is a top view of the sanitary napkin 300 as viewed from the skin side.

[0028] Figure 15 This is a diagram illustrating the structure of the sanitary napkin 300.

[0029] Figure 16 This is a schematic diagram showing a partial enlargement of the absorbent member 33 for explanation. Detailed implementation manners

[0030] Based on the descriptions in this specification and the attached drawings, at least the following matters become clear.

[0031] (Solution 1)

[0032] An absorbent article has a longitudinal direction, a width direction, and a thickness direction in an unfolded state, and includes an absorbent layer capable of absorbing liquid. The absorbent layer is a non-woven fabric having voids formed by a plurality of fibers or a polymer foam having a plurality of pores. In a crotch region that is located at the crotch of a wearer when worn, the weight of the crotch region before absorbing distilled water is defined as the pre-absorption weight, and the weight of the crotch region after immersing the crotch region 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 pre-absorption weight is 5 or more. When the absorbent layer is trisected in the thickness direction, the region closest to the skin side is defined as the skin side region, the region closest to the non-skin side is defined as the non-skin side region, and the region between the skin side region and the non-skin side region is defined as the intermediate region. The narrowness of the voids or pores in the non-skin side region is narrower than the narrowness of the voids or pores in the skin side region. The bending hysteresis 2HB in the KES method of the crotch region is 3.5 gf·cm 2 / cm or less.

[0033] According to the absorbent article of Solution 1, compared with the case where the value obtained by dividing the absorption weight by the pre-absorption weight is less than 5, by setting the value obtained by dividing the absorption weight by the pre-absorption weight to 5 or more, the absorbent article can sufficiently absorb excrement. Regarding the voids or pores, by making the narrowness of the voids or pores in the non-skin side region narrower than the narrowness of the voids or pores in the skin side region, it is easy to introduce the excrement absorbed on the skin side surface of the skin side region to the non-skin side region by capillary action, diffuse the excrement in the non-skin side region, and move the excrement away from the skin of the wearer. Thus, the skin feel can be improved. Furthermore, even when the crotch region is deformed due to the body movement of the wearer in the wearing state, compared with the case where the bending hysteresis 2HB of the crotch region is greater than 3.5 gf·cm 2 / cm, by setting the bending hysteresis 2HB of the crotch region of the absorbent article to 3.5 gf·cm 2 / cm or less, the recovery of the crotch region can be made good, the discomfort caused by the deformation of the crotch region can be reduced, or it can be easy for the crotch region to follow the body movement of the wearer, thereby improving the comfort during wearing.

[0034] (Solution 2)

[0035] According to the absorbent article described in Solution 1, the hydrophilicity of the skin side region is lower than the hydrophilicity of the non-skin side region.

[0036] The absorbent article according to Solution 2 is prone to promoting the diffusion of excrement that is absorbed from the skin-side region to the non-skin-side region. Therefore, in the worn state, it is easy for excrement to move away from the wearer's skin toward the non-skin side, which can reduce the concern that excrement continuously contacts the wearer's skin and can improve the comfort of the wearer in the worn state.

[0037] (Solution 3)

[0038] In the absorbent article described in Solution 1 or 2, a preparation for improving hydrophilicity is provided at least in the non-skin-side region.

[0039] The absorbent article according to Solution 3 is prone to promoting the diffusion to the non-skin-side region. Therefore, in the worn state, it is easy for excrement to move away from the wearer's skin toward the non-skin side, which can reduce the concern that excrement continuously contacts the wearer's skin and can improve the comfort of the wearer in the worn state.

[0040] (Solution 4)

[0041] In the absorbent article described in any one of Solutions 1 to 3, the bending stiffness B in the KES method of the crotch region of the absorbent layer is 2.0 gf·cm 2 / cm or less.

[0042] In the absorbent article according to Solution 4, compared with the case where the bending stiffness B of the absorbent layer is greater than 2.0 gf·cm 2 / cm, the absorbent article can be made softer. Therefore, in the worn state, it is easy for the absorbent article to follow the wearer's body and move, and the comfort in the worn state can be improved.

[0043] (Solution 5)

[0044] In the absorbent article described in any one of Solutions 1 to 4, the thickness of the absorbent layer is 4 mm or less.

[0045] In the absorbent article according to Solution 5, generally, the thicker the absorbent layer, the easier it is for the absorbent layer to harden. Therefore, compared with the case where the thickness of the absorbent layer is greater than 4 mm, the absorbent article can be made softer. Therefore, in the worn state, it is easy for the absorbent article to follow the wearer's body and move, and the comfort in the worn state can be improved.

[0046] (Solution 6)

[0047] In the absorbent article described in any one of Solutions 1 to 5, the absorbent layer is provided with a deformation guiding portion for guiding deformation.

[0048] The absorbent article according to Embodiment 6 is easy to deform the absorbent layer by using the deformation guiding portion, so that the absorbent layer can easily follow the body movement of the wearer in the wearing state, and the comfort of the wearing state can be improved.

[0049] (Embodiment 7)

[0050] In the absorbent article according to any one of Embodiments 1 to 6, the ratio of voids or pores in the non-skin side region in the ratio evaluation test for quantitatively evaluating the ratio of voids or pores in a predetermined region of the absorbent layer is smaller than the ratio of voids or pores in the skin side region in the ratio evaluation test.

[0051] The absorbent article according to Embodiment 7 can easily introduce excrement into the non-skin side region compared to the skin side region by capillary action, and can easily diffuse the excrement absorbed from the skin side of the skin side layer to the non-skin side layer. Therefore, the concern about excrement remaining on the surface of the skin side layer is reduced, and the excrement is kept away from the skin of the wearer. Thus, the comfort of the wearing state can be improved.

[0052] (Embodiment 8)

[0053] In the absorbent article according to any one of Embodiments 1 to 7, the linearity LC of the compression characteristics in the KES method of the crotch region of the absorbent layer is 0.6 or more.

[0054] The absorbent article according to Embodiment 8 can make the skin side layer more resistant to compression compared to the case where the linearity LC of the compression characteristics of the absorbent layer is less than 0.6. Therefore, the deformation of the absorbent member can be reduced, and the discomfort caused by the deformation of the absorbent member to the wearer or the concern about liquid leakage from the absorbent member can be reduced.

[0055] (Embodiment 9)

[0056] In the absorbent article according to any one of Embodiments 1 to 8, the compression resilience RC in the KES method of the crotch region of the absorbent layer is 38% or more.

[0057] The absorbent article according to Embodiment 9 can easily restore the shape of the absorbent layer in the wearing state compared to the case where the compression resilience of the absorbent layer is less than 38%, even when the absorbent layer is deformed due to the body movement of the wearer in the wearing state. Therefore, the absorbent layer can easily be in a state that conforms to the body of the wearer.

[0058] (Embodiment 10)

[0059] In the absorbent article according to any one of Aspects 1 to 9, in the elongation test for measuring the magnitude of the force for elongating the length in the longitudinal direction of the absorbent layer to 1.3 times the length in the longitudinal direction of the absorbent layer, the value obtained by dividing the value of the magnitude of the force measured in the 10th measurement of the elongation test of the absorbent layer by the value of the magnitude of the force measured in the 1st measurement of the elongation test of the absorbent layer is 50% or more.

[0060] The absorbent article according to Aspect 10 can be an absorbent article 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 is less than 50%, 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 50% or more, so that even in the worn state, breakage of the skin-side layer and the non-skin-side layer is reduced, and it is easy to follow the shape and movement of the wearer's body.

[0061] (Aspect 11)

[0062] In the absorbent article according to any one of Aspects 1 to 10, the air permeability resistance value of the absorbent layer is 0.32 kPa·s / m or less.

[0063] The absorbent article according to Aspect 11 can improve the air permeability of the absorbent article compared with 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.

[0064] ===Embodiment===

[0065] As the absorbent article of the present invention, a sanitary napkin (hereinafter also referred to as "sanitary napkin") will be taken as an example to describe the embodiment. However, the absorbent article of the present invention can also be an adult or infant panty-type disposable diaper, tape-type disposable diaper, sanitary short, sanitary napkin, light incontinence pad, absorbent pad, animal disposable diaper, absorbent sheet, fresh water-absorbing pad (Japanese: ドリップシート), etc. In addition, in the case of a fresh water-absorbing pad or the like, the "worn state" in the following embodiment becomes the "use state", and the wearer becomes the "user, etc.". Hereinafter, the worn state will also be referred to as the "use state", and the wearer will also be referred to as the "user, etc.".

[0066] ===First Embodiment===

[0067] <<<Structure of sanitary napkin 1>>>

[0068] Figure 1 It is a top view obtained by observing sanitary napkin 1 (hereinafter also referred to as "sanitary napkin") from the skin side. Figure 2It is a schematic cross-sectional view taken along the line A-A of the sanitary napkin 1. Figure 3 It is a diagram showing the structure of the sanitary napkin 1. Figure 3 It is a schematic diagram showing the components of the sanitary napkin 1 decomposed in the thickness direction, and the detailed structure such as the adhesive for fixing the components to each other and the thickness of each component is omitted. The sanitary napkin 1 has a length direction, a width direction, and a thickness direction that are orthogonal to each other. The side that abuts against the wearer's skin in the thickness direction is the skin side, and the opposite side is the non-skin 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.

[0069] The sanitary napkin 1 has a skin side layer 2, a non-skin side layer 3, a backsheet 4, and side flaps 5. As Figure 3 shown in etc., the sanitary napkin 1 sequentially overlaps 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. The components overlapped in the thickness direction are fixed to each other using an adhesive such as a hot melt adhesive.

[0070] The skin side layer 2 is a skin side piece located at the center of the width direction of the sanitary napkin 1 closest to the skin side, and is an absorption member that abuts against the excretory opening in the worn state and receives the excretions discharged from the excretory opening. The skin side layer 2 is in 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 worn state of the sanitary napkin 1, when the sanitary napkin 1 absorbs excretions, the skin side layer 2 can absorb the excretions and can cause the absorbed excretions to diffuse toward the non-skin side layer 3. Therefore, it is possible to reduce the discomfort to the wearer caused by leakage of excretions from the sanitary napkin 1 or local retention of excretions on the surface of the skin side layer 2 or the like.

[0071] The non-skin side layer 3 is a non-skin side piece 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 in plan view. The non-skin side layer 3 is in a substantially 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 retains the excretions 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 excretions, the non-skin side layer 3 can absorb the excretions and can cause the excretions to diffuse within the non-skin side layer 3. Therefore, it is possible to reduce the discomfort to the wearer caused by leakage of excretions from the sanitary napkin 1 or local retention of excretions on the surface of the skin side layer 2 or the like.

[0072] The skin side layer 2 and the non-skin side layer 3 are respectively made of latent crimped fibers 2f and latent crimped fibers 3f (refer toFigure 5 ) a non-woven fabric (non-woven fabric sheet) formed. 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 made of polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters (PET, PBT), polyamides, 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".

[0073] "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 bonded together by interlacing, and / or fusing, and / or adhesion (JIS L0222:2001 Non-woven fabric terminology 101). That is, a non-woven fabric is a fabric that is integrated without weaving fibers and is a sheet material with 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 with a maximum load capacity of 50 N. When measuring the separation strength of a non-woven fabric sheet, hold the front end of one side of the non-woven fabric sheet in the long side direction or the short side direction 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) in such a way 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.

[0074] 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 (needle-punched 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 formed by interlacing fibers with each other using water flow without using an adhesive.

[0075] 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.

[0076] (a) First, a non-skin-side fibrous web having a form such as a carded web is formed by processing hydrophilic fibers 2fb (fibers 2f forming at least a part of the non-skin-side region Rd to be described later) using a carding machine or the like.

[0077] (b) Next, while conveying the non-skin-side fibrous web, a skin-side fibrous web having a form such as a carded web, which is obtained by processing hydrophobic fibers 2fa (fibers 2f forming 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 fibrous web to obtain a laminated web.

[0078] (c) By applying a high-pressure water flow such as a water jet from the skin side toward the non-skin side in the thickness direction of the laminated web, the fibers between the respective fiber layers and the fibers of the respective webs are intertwined with each other to obtain a laminate.

[0079] (d) Finally, the laminate is put into a dryer and heated to a temperature at which the latent crimpable fibers can be crimped, whereby an integrated nonwoven fabric sheet (skin-side layer 2) is obtained. This nonwoven fabric sheet has voids formed by a plurality of fibers 2f.

[0080] The nonwoven 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 nonwoven fabric sheet of the skin-side layer 2. However, the nonwoven 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.

[0081] The latent crimpable fibers 2f, 3f are fibers that are crimped by heat treatment and exhibit a helical shape. Among the latent crimpable fibers, for example, there are side-by-side type composite fibers in which a high-shrinkage component and a low-shrinkage component are arranged side by side, and eccentric sheath-core 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 one point. When the latent crimpable fibers are crimped, the latent crimpable fibers are crimped in a coiled shape, for example.

[0082] As the plurality of resins having different thermal shrinkage rates or thermal expansion rates for forming the latent crimpable fibers 2f, 3f, as long as they are combinations of resins having different thermal shrinkage rates or thermal expansion rates from each other, they can be used without particular limitation, and can also be combinations of the same type or single resins, or combinations 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 crimpable 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.

[0083] The non-woven fabrics of the skin-side layer 2 and the non-skin-side layer 3 in this embodiment are a combination of polyester resins (single-component resins). Specifically, potential crimpable fibers made of a combination of polyethylene terephthalate (PET) and modified PET are used. In addition, 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. Specific examples of the glycol component other than ethylene glycol include 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene ether glycol, and the like. In addition, specific examples of the dicarboxylic acid component other than terephthalic acid include isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, and the like. And a net-like material composed of potential crimpable fibers made of a combination of PET and modified PET is formed by a net-forming unit such as a carding machine. For this net-like material, the fibers are interwoven with each other by the hydroentangling method to become a non-woven fabric state, and it is heated to a predetermined temperature to make the potential crimpable fibers exhibit crimping. Thus, the non-woven fabrics of the skin-side layer 2 and the non-skin-side layer 3 are manufactured. As a result, the unit area weight of the potential crimped fibers of the heated non-woven fabric is larger than the unit area weight of the potential crimpable fibers in the non-woven fabric state before heating. That is to say, the non-woven fabric shrinks due to the crimping of the potential crimpable fibers, and the unit area weight of the fibers becomes larger.

[0084] The skin-side layer 2 and the non-skin-side layer 3 are each an absorption layer 10 having a liquid permeability, a liquid absorption function, and a liquid retention function and having a predetermined thickness. In this embodiment, the skin-side layer 2 and the non-skin-side layer 3 will be described as the absorption layer 10. Figure 4 It is a diagram for explaining the absorption layer 10 of the sanitary napkin 1. In the sanitary napkin 1, the skin-side layer 2 is a skin-side sheet that abuts against the skin of the wearer. It is the member that first bears excrement in the wearing 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.

[0085] 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 (potential crimped fibers) 2f, 3f. Figure 5 A is a diagram schematically showing a cross-section of the skin-side layer 2, Figure 5FIG. B schematically shows a cross-section of the non-skin side layer 3, and the dimensions etc. are not necessarily accurate. In addition, the voids in the skin side layer 2 and the non-skin side layer 3 can be voids between non-continuous (multiple fibers) fibers, or voids formed by a single continuous fiber being bent or helical, or voids formed by a combination of the above voids. The voids formed by multiple fibers 2f, 3f refer to the spaces and regions in the skin side layer 2 and the non-skin side layer 3 where multiple fibers 2f, 3f are not provided. In addition, the voids are not only the spaces surrounded by the fibers 2f, 3f or the spaces enclosed by the fibers, but can also be spaces where at least a part of the voids formed by the fibers 2f, 3f is open.

[0086] 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 intertwined with each other back and forth between the fibers 2f, 3f by using the crimp of the fibers 2f, 3f. For example, the distance between the fibers 2f, 3f is shortened due to crimping, or other fibers enter between the fibers 2f, 3f whose distance has been shortened, and the voids between the fibers 2f, 3f become smaller. Therefore, the voids formed by the fibers 2f, 3f containing latent crimped fibers are smaller than the voids formed by multiple fibers in a normal non-woven fabric made of non-crimped fibers.

[0087] In addition, for the latent crimped fibers 2f, 3f provided in the skin side layer 2 and the non-skin side layer 3 respectively, the fibers themselves are not easily absorbent. For example, in fibers such as pulp fibers, when they absorb liquid (excrement), the thickness of the fibers becomes thicker, but even when the latent crimped fibers 2f, 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. Therefore, in the skin side layer 2 and the non-skin side layer 3, in the wearing state, even when the sanitary napkin 1 has absorbed excrement, for the latent crimped fibers 2f, 3f in the skin side layer 2 and the non-skin side layer 3, the thickness of the fibers themselves is not easily thickened. By the thickness of the fibers themselves not being easily thickened, the size of the voids formed by the fibers 2f, 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, 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, 3f and have voids formed by the fibers 2f, 3f, so they also have excellent air permeability, can reduce the stuffiness and skin roughness brought to the wearer in the wearing state, and can improve the comfort of the wearing state.

[0088] 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 fineness are used throughout the region. In the present embodiment, the fineness 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. Also, the ratio of the voids in the skin-side layer 2 (the ratio of the region in the skin-side layer 2 where the fibers 2f are not provided) is 94%. The basis weight per unit area of the skin-side layer 2 is approximately 170 gsm. Further, 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.

[0089] 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 fineness are used throughout the region in the thickness direction. The fineness of the potential crimped fiber 3f in the non-skin side layer 3 of the present embodiment is set to 2.2 dtex. The basis weight per unit area of the non-skin side layer 3 is approximately 120 gsm. Preferably, the basis weight per unit area of the fibers 3f in the non-skin side layer 3 is 80 gsm or more and 200 gsm or less.

[0090] The non-skin side layer 3 has a linear high-density portion DH where the density of the fibers 3f is higher than that of the surroundings (low-density portion DL) and a low-density portion DL where the density of the fibers 3f is lower than that of the high-density portion DH. The high-density portion DH is a portion where the thickness is thinner than that of the surroundings (low-density portion DL) and the fibers are not fused to each other.

[0091] 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 sheet materials 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, hydrophobic air-through nonwoven fabric, hydrophobic spunbond nonwoven fabric, or the like can be exemplified.

[0092] In addition, the sanitary napkin 1 has a pair of wing portions 1w extending outward in the width direction at a substantially central portion in the length direction. The wing portions 1w are formed by the side sheets 5 and the backsheet 4. Further, it is also possible that the sanitary napkin 1 does not necessarily have the wing portions 1w. When the sanitary napkin 1 does not have the wing portions 1w, it may or may not have the side sheets 5.

[0093] 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.

[0094] In the compression section 20, the thickness of the sanitary napkin 1 is thinner compared to its surroundings, and the fiber density of the sanitary napkin 1 (skin-side layer 2 and non-skin-side layer 3) becomes higher. These comparisons are preferably made using known methods. As a comparison of the thickness of the sanitary napkin 1, methods such as visual comparison can be exemplified, or values measured by applying pressure to an object part, for example, using a dial thickness gauge ID-C1012C manufactured by Mitutoyo Corporation or an equivalent instrument, and then comparing them. 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 section 20 is not limited to the 2 shape shown. For example, it may also be a shape in which a plurality of dot-like compression sections are discretely arranged. Figure 1

[0095] <<<Regarding the absorbent layer 10>>>

[0096] As described above, the absorbent layer 10 is also 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. The absorbent layer 10 of 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 having latent crimp fibers and has voids formed by the fibers 2f. The non-skin-side layer 3 has a plurality of fibers 3f having latent crimp fibers and has voids formed by the fibers 3f.

[0097] The skin-side layer 2 is a non-woven fabric sheet with 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 with 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 with a thickness of H10 (H2 + H3). In each layer, excrement can be absorbed and retained using the voids formed by a plurality of fibers 2f and 3f, and the air permeability can be improved using the voids. By improving the air permeability of the absorbent layer 10, discomfort such as stuffiness felt by the wearer of the sanitary napkin 1 can be reduced.

[0098] ​In addition, the fibers 2f and 3f in the absorbent layer 10 do not necessarily have to be only latent crimped fibers (100% latent crimped fibers). Either one or both of the fibers 2f and 3f may contain fibers other than latent crimped fibers (e.g., liquid-absorbent fibers such as pulp fibers). Additionally, the absorbent layer 10 may contain not only the fibers 2f and 3f but also superabsorbent polymers (SAP), etc.

[0099] The absorbent layer 10 of the sanitary napkin 1 has a structure in which the skin-side layer 2 and the non-skin-side layer 3, each having an absorbent function, are overlapped with each other. In addition, the skin-side layer 2 and the non-skin-side layer 3 may be fixed using 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. Thus, the concern that the absorption of excrement is hindered by the adhesive in the worn state can be reduced.

[0100] The sanitary napkin 1 of the present embodiment has a desired absorbent function in the crotch region M that is located in the wearer's crotch when worn. The "crotch region" is also referred to as the "groin portion" where the sanitary napkin 1 is in close contact with the wearer's groin in the worn state. The crotch region M of the sanitary napkin 1 is a region that includes the central portion in the longitudinal direction and is a region where the wing portions 1w are provided.

[0101] Regarding this crotch region M, when the weight of the crotch region M before absorbing distilled water is set as the pre-absorption weight (a), and the weight of the crotch region M after immersing the crotch region M 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 (A), and when the value obtained by subtracting the pre-absorption weight (a) from the post-absorption weight (A) is set as the absorption weight (b) of distilled water (b = A - a), the value obtained by dividing the absorption weight (b) by the pre-absorption weight (a) is 5 or more (b / a ≥ 5).

[0102] In addition, in the thickness direction of the absorbent layer 10 in the crotch region M, the side in contact with the wearer's skin is the skin side, and the opposite side of the skin side is the non-skin side. As Figure 6 shown, 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. Figure 6 is a schematic view showing Figure 4 a schematic cross-sectional view taken along the line B - B in. Regarding the voids formed by the fibers 2f and 3f in the absorbent layer 10, the narrowness of the voids in the non-skin-side region Qd is narrower than the narrowness of the voids in the skin-side region Qu.

[0103] In addition, the bending hysteresis 2HB of the crotch region M based on the KES method is 3.5 gf·cm 2 or less per cm.

[0104] The larger the value obtained by dividing the absorption weight b by the weight a before absorption, the more distilled water the sanitary napkin 1 can absorb, 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 can sufficiently ensure the function of absorbing liquid. In addition, the absorbed liquid can be retained within the absorbent layer 10.

[0105] In addition, regarding the voids formed by the fibers 2f and 3f, since the narrowness of the voids in the non-skin side region Qd is narrower than the narrowness of the voids in the skin side region Qu, it is easy to introduce the excrement borne on the skin side surface of the skin side region Qu in the absorbent layer 10 in the wearing state toward the non-skin side region Qd by 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. Thereby, 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 due to 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 toward the non-skin side region Qd, and thus 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 absorbent layer 10 is in contact with the wearer's skin, regarding the voids formed by the fibers 2f and 3f, by making the narrowness of the voids in the non-skin side region Qd narrower than the narrowness of the voids in the skin side region Qu, it is easy to make the excrement diffuse from the skin side toward the non-skin side within the absorbent layer 10, and thus it is possible to reduce the excrement staying on the skin side surface of the absorbent layer 10 and improve the comfort brought to the wearer in the wearing state. In addition, in the absorbent layer 10, regarding the voids formed by the fibers 2f and 3f, compared with the case where the narrowness of the voids in the non-skin side region Qd is wider than the narrowness of the voids in the skin side region Qu, by making the narrowness of the voids in the non-skin side region Qd narrower than the narrowness of the voids in the skin side region Qu to promote the diffusion of the excrement from the skin side region Qu to the non-skin side region Qd, it is possible to make the diffusion area of the excrement in the skin side region Qu smaller and the diffusion area of the excrement in the non-skin side region Qd larger. Thereby, it is easy to promote the diffusion of the excrement from the skin side to the non-skin side in the absorbent layer 10, and it is easy to promote the diffusion of the excrement in the part of the absorbent layer 10 on the non-skin side compared to the part on the skin side. Therefore, asFigure 7 As shown, it is easy to make the diffusion region B3 of excrement in the non-skin side layer 3 larger than the diffusion region B2 of excrement in the skin side layer 2. Figure 7 This is a diagram illustrating the sanitary napkin 1 after 30 minutes from dropping horse blood. Figure 7 This is a diagram illustrating the state of the sanitary napkin 1 after dropping 6 mm of horse blood at the central part in the length direction and the central part in the width direction of the sanitary napkin 1 and after 30 minutes. In this way, since the area of the diffusion region B3 of excrement in the non-skin side layer 3 is larger than the area of the diffusion region B2 of excrement in the skin side layer 2, it is easy to give an impression to users and the like that the absorbency of the sanitary napkin 1 is excellent.

[0106] Furthermore, the bending hysteresis 2HB value represents bending recovery. The larger the value of the bending hysteresis 2HB, the worse the recovery. Therefore, compared with the case where the bending hysteresis 2HB based on the KES method at the central part in the length direction and the central part in the width direction of the absorbent layer 10 is greater than 3.5 gf·cm 2 / cm, by setting the bending hysteresis 2HB based on the KES method at the central part in the length direction and the central part in the width direction of the absorbent layer 10 to 3.5 gf·cm 2 / cm or less, the recovery of the crotch region M can be made good in the wearing state. Even when the absorbent layer 10 is deformed due to external forces generated by the shape and movement of the wearer's body, it is easy for the absorbent layer 10 to return to its original shape, and the discomfort caused by the deformation of the absorbent layer 10 in the crotch region M can be reduced, or it is easy for the absorbent layer 10 to follow the wearer's body and movement, thereby improving the comfort during wearing.

[0107] As described above, in the sanitary napkin 1 of the present embodiment, each non-woven fabric sheet of the skin-side layer 2 and the non-skin-side layer 3 is formed by a hydroentangling method. By pouring water flows from the skin side toward the non-skin side respectively, it becomes easy to press the fibers 2f and 3f from the skin side toward the non-skin side. Thus, the narrowness of the voids in the non-skin-side region Qd becomes narrower than the narrowness of the voids in the skin-side region Qu. In addition, when comparing the skin-side layer 2 and the non-skin-side layer 3 constituting the absorbent layer 10, the narrowness of the voids in the non-skin-side layer 3 is narrower than the narrowness of the voids in the skin-side layer 2. The difference in the narrowness of the voids 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, the degree of interlacing of the fibers 2f and 3f based on the hydroentangling method, and the like. In addition, as a method of making the narrowness of the voids in the non-skin-side region Qd narrower than the narrowness of the voids in the skin-side region Qu, it is not limited thereto. For example, the fineness (fiber diameter) of the fibers in the non-skin-side region Qd may be made finer than the fineness (fiber diameter) of the fibers in the skin-side region Qu. Alternatively, potential crimp fibers having a stronger crimp property than the fibers used for the skin-side region Qu may be used for the fibers in the non-skin-side region Qd to make the narrowness of the voids in the non-skin-side region Qd narrower than the narrowness of the voids in the skin-side region Qu.

[0108] <Absorption function measurement method>

[0109] The absorption function of the crotch region M of the sanitary napkin 1 can be measured by the following absorption test.

[0110] (1) First, the backsheet 4 is removed from the sanitary napkin 1. The backsheet 4 is a liquid-impermeable member and clearly does not contribute to the absorption function, so it is removed.

[0111] (2) A predetermined region is cut out from the crotch region M of the sanitary napkin 1 from which the backsheet 4 has been removed as a sample. In the sanitary napkin 1 of the present embodiment, the sample has a size of 70 mm × 70 mm.

[0112] (3) Then, the pre-absorption weight a as the weight of the sample is measured 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.

[0113] (4) Next, one end of the sample is clamped using a jig, and the front end of the jig and the sample are set in a state perpendicular in the longitudinal direction.

[0114] The sample together with the jig is immersed in a water tank containing distilled water (or deionized water) at 23 ± 1°C. At this time, the skin side of the absorbent layer 10 is made the upper side. The sample is gently pressed toward the water, and the state where the entire sample is completely immersed in the distilled water is maintained for 60 seconds.

[0115] (5) After that, lift the jig, 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 jig and suspend the sample from the jig for 90 seconds.

[0116] (6) After that, weigh the mass of the sample excluding the jig to obtain the absorbed weight A as the weight of the sample after absorption.

[0117] (7) Then, the value obtained by subtracting the weight a before absorption from the absorbed weight A is the absorbed weight b.

[0118] (Absorbed weight b) = (Absorbed weight A) - (Weight a before absorption)

[0119] Preferably, the value obtained by dividing the obtained absorbed weight b by the weight a before absorption is 5 or more.

[0120] Absorbed weight b ÷ Weight a before absorption ≥ 5

[0121] Perform the above (1) to (7) for each of the 5 samples, and set the average value of the results of the 5 samples as the measurement result.

[0122] Figure 8 A is a graph showing the measurement results of the absorption test of the crotch region M of the sanitary napkin 1. Figure 8 The numbers 1 to 3 in A are the average values of the results of the 5 samples respectively. As Figure 8 As shown in A, in the crotch region M of the sanitary napkin 1 of the present embodiment, the value obtained by dividing the weight of the distilled water absorbed (absorbed weight b) by the weight of a predetermined region before absorbing the distilled water is greater than 7 respectively. That is, 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 excrement, and can reduce the concern of excrement leakage from the sanitary napkin 1.

[0123] In addition, the following situations can be compared by a known method: Regarding the voids formed by the fibers 2f and 3f in the absorbent layer 10 of the crotch region M, the narrowness of the voids in the non-skin side region Qd is narrower than the narrowness of the voids in the skin side region Qu. For example, for the comparison of the narrowness of the voids, when the narrowness and size of the voids can be visually recognized, the narrowness of the voids can be compared, or magnified cross-sectional photos of each region can be taken and the narrowness of the voids can be compared using the taken magnified cross-sectional photos. Furthermore, in the case of more precisely comparing the narrowness of the voids, the narrowness evaluation test shown below can be used to compare the narrowness of the voids.

[0124] <Narrowness evaluation test method and void ratio evaluation test method>

[0125] The narrowness evaluation test and the void ratio evaluation test described later can also be performed using the following method.

[0126] First, X-ray CT measurement is performed on the absorbent layer 10 in the crotch region M of the sanitary napkin 1. Using a high-resolution 3D X-ray microscope nano3DX manufactured by Rigaku Corporation, non-destructive tomography (CT measurement) is performed under the following conditions.

[0127] X-ray source: Cu

[0128] Tube voltage - tube current: 40 kV - 30 mA

[0129] Detector: sCMOS camera (lens: 1080)

[0130] Resolution: 2.51 μm / voxel

[0131] A measurement region (predetermined region) Y of the absorbent layer 10 in the crotch region M is randomly extracted from the three-dimensional data obtained by shooting, and the voids are analyzed. In addition, the measurement region Y used for this analysis is a rectangular parallelepiped (which can also 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.

[0132] In the present embodiment, as Figure 9 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 9 It is a diagram illustrating the measurement region Y. The fibers 2f and 3f are colored (gray) parts, the voids are colored (white) parts, and the lattice part indicates 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).

[0133] 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.

[0134] 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 from tomographic images obtained by X-ray CT. For example, the void ratio of the first region Y1 is as follows.

[0135] Void ratio of the first region Y1 = (Volume of voids in the first region Y1) / (Volume of the first region Y1)

[0136] 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.

[0137] Regarding the narrowness of the voids in each of the regions Y1 to Y3, "A new method for the mo del-independent assessment of thickness in three-dimensional images" (by T. HILDEBRAND & P. RUEGSEGGER, Journal of Microscopy, Vol. 185, Pt1, January 1997, pp. 67 - 75) Thickness is applied to the spatial part and the distribution of the void narrowness and the average narrowness of the voids are calculated based on the results of the narrowness of a part of the volume (voids). That is, "Thickness" in the definition of the above-mentioned literature corresponds to the "narrowness of the voids" 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 voids in the tomographic image obtained by X-ray CT, the distribution of the void narrowness and the average narrowness of the voids can be obtained.

[0138] An outline of a method for quantitatively evaluating the narrowness of the voids (such as void Z) inside each of the analyzed regions Y1 to Y3 will be described. Figure 10 This is a diagram showing an outline of a method for evaluating the narrowness in void Z. For example, as Figure 10 shown, at arbitrary points P1 to P4 inside the void Z, spheres with the largest volume 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 10 describes the process of obtaining the diameters D1 to D4 of the spheres at the four points (points P1 to P4), but in the actual quantitative evaluation of the narrowness of the voids, the following process is carried out: the process of obtaining the diameters D of the spheres at multiple points P inside the void Z. This 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 voids in each of the regions Y1 to Y3 can be quantitatively evaluated.

[0139] <Method for Measuring Bending Hysteresis 2HB>

[0140] The bending hysteresis 2HB (bending restorability) can be measured by a known method.

[0141] For example, it can be measured using an automated bending testing machine (KES-FB2-L) manufactured by Kato Tech Co., Ltd.

[0142] 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 portion in the crotch region M of the absorbent layer 10 as a sample.

[0143] Next, hold both ends of the sample in the longitudinal direction using a chuck. Then, bend the sample in both forward and reverse directions at a curvature change rate of 0.1 cm -1 / min within a range where the curvature becomes 0.5 cm on the positive side -1 and 0.5 cm on the negative side -1 to obtain a hysteresis curve of the bending moment required for bending in each direction. Set the hysteresis amount of the bending moment when the curvature is 0.1 cm -1 as the bending hysteresis 2HB.

[0144] In Figure 8 FIG. B shows the measurement results of the bending hysteresis 2HB (gf·cm 2 / cm) of the absorbent layer 10 in the crotch region M of the sanitary napkin 1 of the present embodiment based on the KES method. As Figure 8 shown in FIG. B, the bending hysteresis 2HB (gf·cm 2 / cm) at the central portion in the longitudinal direction and the central portion in the width direction of the absorbent layer 10 of the sanitary napkin 1 of the present embodiment is 0.8204 gf·cm 2 / cm to 0.9253 gf·cm 2 / cm, and is thus clearly 3.5 gf·cm 2 / cm or less. In the sanitary napkin 1, 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 for the absorbent layer 10 to return 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.

[0145] In addition, preferably, the proportion of voids in the non-skin side region Qd in the void proportion evaluation test for quantitatively evaluating the proportion of voids in a predetermined region (measurement region Y) of the absorbent layer 10 is smaller than the proportion of voids in the skin side region Qu in the void proportion evaluation test. The void proportion evaluation test is performed using the above-described method. Thus, when the sanitary napkin 1 (absorbent layer 10) absorbs excrement, it is easy to introduce the excrement from the skin side region Qu to the non-skin side region Qd with a smaller proportion of voids by capillary action, and it is easy to promote the diffusion of the excrement within the non-skin side region Qd. In addition, in the worn state, the excrement staying in the skin side region Qu is reduced, and the excrement is kept away from the skin of the wearer. Thus, the discomfort caused by the contact between the excrement and the skin of the wearer can be reduced, and the comfort of the worn state can be improved.

[0146] 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, and by pouring water from the skin side toward the non-skin side, the fibers 2f, 3f are pressed from the skin side toward the non-skin side. Therefore, the proportion of voids in the non-skin side region Qd in the void proportion evaluation test is smaller than the proportion of voids in the skin side region Qu in the void proportion evaluation test. In addition, the method for making the proportion of voids in the non-skin side region Qd in the void proportion evaluation test smaller than the proportion of voids in the skin side region Qu in the void proportion evaluation test is not limited thereto. For example, the fineness (fiber diameter) of the fibers in the non-skin side region Qd may be made finer than the fineness (fiber diameter) of the fibers in the skin side region Ru. In addition, it may be that, by using latent crimped fibers having a stronger crimping property than the fibers used for the skin side region Ru for the fibers used for the non-skin side region Rd, the proportion of voids in the non-skin side region Rd in the void proportion evaluation test is made smaller than the proportion of voids in the skin side region Ru in the void proportion evaluation test.

[0147] In addition, preferably, the hydrophilicity of the skin side region Qu of the absorbent layer 10 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. Thereby, the concern that the excrement absorbed by the skin side region Qu in the wearing state stays in the skin side region Qu can be reduced, and it is easy to introduce the excrement toward the non-skin side region Qd. In addition, it is easy to diffuse 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 the excrement continuously contacts the wearer's skin can be reduced, and the concern that the excrement continuously contacts the wearer's skin can be reduced, thereby improving the comfort of the wearer in the wearing state.

[0148] 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 performed by the following method.

[0149] First, a measurement sample having a quadrilateral shape in plan view with a length direction of 150 mm and a width direction of 70 mm is cut out from the region to be measured (when it is difficult to cut out, the maximum length and maximum width are not limited to the illustrated values as long as they are within the measurable range). Then, a droplet of ion-exchanged water is attached to the measurement surface of the contact angle in each measurement sample, the droplet is recorded, and the contact angle is measured based on the recorded image. More specifically, as the measurement device, a microscope VHX-1000 manufactured by Keyence Corporation is used, and a medium magnification zoom lens is installed in the measurement device in an inverted state at 90°. Each measurement sample is placed 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, a 3 μL droplet of ion-exchanged water is attached to the measurement surface of each measurement sample placed on the measurement stage, the image of the droplet is recorded and input to the measurement device. Among the recorded multiple images, 10 images with clear ends or one end in the width direction of the droplet are selected, the contact angle of the droplet is measured for each of the 10 images, and the average value of their contact angles is set as the contact angle of the region (fiber layer) to be measured. The measurement environment is set to 20 °C / 50% RH.

[0150] The smaller the contact angle with water measured by the above method, the higher the hydrophilicity (the lower the hydrophobicity); 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; if the contact angle is 90 degrees or more, it is hydrophobic. That is to say, in the skin side layer 2, the contact angle with water in the Ru side of the skin side region is larger than that in the Rd side of the non-skin side region.

[0151] In the absorbent layer 10 of the present embodiment, hydrophobic fibers 2fa are provided at the position closest to the skin side (the upper layer 2A of the skin side layer 2) in the thickness direction, and hydrophilic fibers 2fb and 3f are provided at positions closer to the non-skin side than the upper layer 2A. Thus, the hydrophilicity of the skin side region Qu is made lower than that of the non-skin side region Qd, but it is not limited thereto. For example, the entire region (the skin side region Qu, the middle region Qm, and the non-skin side region Qd) of the non-woven fabric sheet of the absorbent layer 10 is formed of fibers 2f and 3f with a constant hydrophilicity, and the skin side region Qu of the absorbent layer 10 (two non-woven fabric sheets) can be processed by coating a preparation (hydrophobic agent) for improving hydrophobicity, or the non-skin side region Qd of the absorbent layer 10 (two non-woven fabric sheets) can be processed by coating a preparation (hydrophilic agent) for improving hydrophilicity. By using a preparation for improving hydrophobicity in the skin side region Qu or a preparation for improving hydrophilicity in the non-skin side region Qd, it is easy to promote the diffusion of excrement from the skin side region Qu to the non-skin side region Qd. Thus, in the wearing state, it is easy to make the excrement move away from the wearer's skin to the non-skin side, reducing the concern that the excrement continuously contacts the wearer's skin, and thereby improving the comfort of the wearer in the wearing state.

[0152] Preferably, the bending stiffness B based on the KES method of the crotch region M of the absorbent layer 10 in the sanitary napkin 1 is 2.0 gf·cm 2 / cm or less. Generally speaking, 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 crotch region M of the absorbent layer 10 is greater than 2.0 gf·cm 2 / cm, by setting the bending stiffness B based on the KES method of the crotch region M of the absorbent layer 10 to 2.0 gf·cm 2 / cm or less, the absorbent layer 10 can be made softer, and it is easy to make the sanitary napkin 1 using the absorbent layer 10 softer. Therefore, in the wearing state, the sanitary napkin 1 can easily follow the shape and movement of the wearer's body, reduce the discomfort brought to the wearer, and improve the comfort in the wearing state.

[0153] <Measurement method of bending stiffness B>

[0154] The bending stiffness B (gf·cm of the crotch region M of the absorbent layer 102 ( / cm) can be measured by known methods. For example, the bending stiffness B (gf·cm 2 / cm) can be measured using the KES-FB2-L large bending measurement test machine manufactured by Kato Tech Co., Ltd. First, take out the absorbent layer 10 (the skin-side layer 2 and the non-skin-side layer 3) from the sanitary napkin 1, and cut out a 50 mm × 50 mm portion in the crotch region M of the absorbent layer 10 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 absorbent layer 10. Bend it to the front side to a maximum curvature of +0.5 cm -1 , and then, bend it to the back side to a maximum curvature of -0.5 cm -1 , and then restore it, and thus measure. The bending stiffness value B (gf·cm 2 / cm) is calculated based on the average value of the slope of the bending moment with respect to the curvature of 0.1 - 0.3 when bending to the front side and the slope of the bending moment with respect to the curvature of -0.1 - -0.3 when bending to the back side.

[0155] As Figure 8 shown in B, the bending stiffness B (gf·cm 2 / cm) of the crotch region M of the absorbent layer 10 of the sanitary napkin 1 in this embodiment is 0.1008 gf·cm 2 / cm to 1.1017 gf·cm 2 / cm. In this way, the bending stiffness B in the crotch region M of the sanitary napkin 1 is 2.0 gf·cm 2 / cm or less. Therefore, compared with the case where the bending stiffness B in the crotch region M is greater than 2.0 gf·cm 2 / cm, the absorbent layer 10 can be made softer, and thus the sanitary napkin 1 can be made softer. As a result, for the sanitary napkin 1, in the worn 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 worn state.

[0156] In the sanitary napkin 1, preferably, the thickness of the absorbent layer 10 (the skin-side layer 2 and the non-skin-side layer 3) is 4 mm or less. In absorbent articles such as the sanitary napkin 1, the absorbent layer 10 is a member that particularly has a thickness and a relatively high stiffness. The thicker the absorbent layer 10, the easier it is for the absorbent layer 10 to harden, and as the sanitary napkin 1, the easier it is for the stiffness to become higher. Therefore, compared with the case where the thickness of the absorbent layer 10 is greater than 4 mm, by setting the thickness of the absorbent layer 10 to 4 mm or less, the stiffness of the sanitary napkin 1 can be reduced, and the sanitary napkin 1 can be made softer. As a result, in the worn state, it is easy for the sanitary napkin 1 to follow the body and movement of the wearer, and the comfort in the worn state can be improved.

[0157] Alternatively, it may be that the absorbent layer 10 is provided with a deformation guiding portion for guiding deformation. By providing the absorbent layer 10 with the deformation guiding portion, it becomes easy to deform the absorbent layer following the guidance of the deformation guiding portion. Therefore, in the worn state, it is easy for the absorbent layer 10 to follow the shape and movement of the wearer's body, and the comfort in the worn state can be improved. For the deformation guiding portion of the absorbent layer 10, examples thereof include a compressed portion (compression groove) formed by compressing the absorbent layer 10 in the thickness direction, a concave portion (groove portion) that locally or entirely thins the thickness of the absorbent layer 10, a slit, or a portion of the absorbent layer 10 where the weight per unit area of the fibers changes, etc., which are portions that change the stiffness of the absorbent layer 10.

[0158] Preferably, the linearity LC (compression hardness) of the compression characteristics based on the KES method in the crotch region M of the absorbent layer 10 of 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 of the absorbent layer 10 is less than 0.6, by setting the linearity LC (compression hardness) of the compression characteristics of the absorbent layer 10 to 0.6 or more, the deformation of the absorbent layer 10 can be reduced. Therefore, the discomfort caused by the deformation of the absorbent layer 10 to the wearer in the worn state can be reduced, and the comfort in the worn state can be improved. In addition, concerns such as leakage of excrement from the absorbent layer 10 due to deformation of the absorbent layer 10 can be reduced.

[0159] Alternatively, 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% or more. The closer the value of the compression resilience RC (compression recovery) is to 100%, the higher the recovery property. 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%, 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% or more, it becomes easy for the shape of the absorbent layer 10 to be restored. Therefore, even when a force is applied to the sanitary napkin 1 in the worn state and the absorbent layer 10 is deformed, the concern about forming wrinkles on the skin side of the sanitary napkin 1 can be reduced. In addition, it is easy to reduce the discomfort caused by the deformation of the absorbent layer 10 to the wearer in the worn state, and it is easy to fit to the wearer's body.

[0160] <Method for Measuring Compression Resilience LC and Compression Resilience RC>

[0161] Compressive resilience LC (compressive hardness) and compressive resilience RC (compressive recovery) can be measured using known methods. For example, they can be measured using the automated compression testing machine KES-FB3 AUTO-A manufactured by Kato Tech Co., Ltd.

[0162] First, take out the absorbent layer 10 from the sanitary napkin 1 (in a state where the skin-side layer 2 and the non-skin-side layer 3 are overlapped), and cut out a 50 mm × 50 mm portion in the crotch region M of the absorbent layer 10 as a sample.

[0163] Compress each sample between steel plates with circular planar terminals having an area of 200 mm 2 Set the compression speed to 50 sec / mm and the maximum compression load to 50 gf / cm 2 , and measure the compression characteristics of the sample.

[0164] For the recovery process, also measure the compression characteristics at the same speed, and obtain the linearity LC and compression recovery rate RC [%], and compression work WC [gf·cm / cm 2 of the compression characteristic curve obtained from the measurement.

[0165] Figure 8 C is a graph showing the measurement results of the compression characteristics based on the KES method. As Figure 8 shown in C, the linearity LC of the compression characteristics in the crotch region M of the absorbent layer 10 of the sanitary napkin 1 in this embodiment is 0.609 to 0.653, so it is above 0.6. Thus, for the absorbent layer 10 of the sanitary napkin 1 in this embodiment, compared with the case where the linearity LC of the compression characteristics is less than 0.6, 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.

[0166] For the compressive resilience RC, as Figure 8 also shown in C, the compressive resilience RC in the crotch region M of the absorbent layer 10 of the sanitary napkin 1 in this embodiment is 38.80% to 40.18%, which is significantly greater than 38%. For the absorbent layer 10 of the sanitary napkin 1, compared with the case where the compressive resilience RC is less than 38%, 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, so the comfort in the wearing state can be improved.

[0167] Furthermore, preferably, in the elongation test for measuring the magnitude of the force for elongating the absorbent layer 10 (in a state where the skin-side layer 2 and the non-skin-side layer 3 are overlapped) by a predetermined length, the value obtained by dividing the value of the magnitude of the force measured in the 10th measurement of the elongation test of the absorbent layer 10 by the value of the magnitude of the force measured in the 1st measurement of the elongation test of the absorbent layer 10 is 55% or more. By 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 being 55% or more, breakage of the absorbent layer 10 can be reduced even in the worn state, and 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 55%, even when the absorbent layer 10 is repeatedly forced to elongate, 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 can be formed into 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.

[0168] <Method of Measuring Elongation Test>

[0169] The elongation test can be measured by a cyclic test using an AUTOGRAPH type tensile testing machine manufactured by Shimadzu Corporation, for example, model AG-1KNI. The specific measurement method is as follows.

[0170] First, the absorbent layer 10 (in a state where the skin-side layer 2 and the non-skin-side layer 3 are overlapped) 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 length 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).

[0171] Next, the material in the state of a chuck distance of 100 mm is elongated in the length 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.

[0172] Then, calculate the value obtained by dividing the measurement result value of the 10th measurement (the value of the magnitude of the force measured in the 10th measurement) by the measurement result value of the 1st measurement (the value of the magnitude of the force measured in the 1st measurement).

[0173] Figure 11 It is a graph showing the measurement results of the elongation test of the absorbent layer 10. The measurement results (magnitude of force) of the elongation test of the absorbent layer 10 of the sanitary napkin 1 are as Figure 11 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 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 of the elongation test (15.270 [N]) 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 55% or more. For the absorbent layer 10 of the sanitary napkin 1, the value is also greater than 0 N in the 10th measurement result. Thus, even when an external force is applied in the wearing state, breakage and fracture of the absorbent layer 10 can be reduced. In addition, 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 55%, 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.

[0174] Regarding the 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 discomfort such as stuffiness felt by the wearer of the sanitary napkin 1 can be reduced.

[0175] The measurement of the air permeability resistance value of the absorbent layer 10 can be carried out by using a known method. For example, cut out the absorbent layer 10 in the crotch region M in a predetermined size (for example, a circle with a diameter of 70 mm × 70 mm) and use it as a sample. Then, using a gas permeability tester (KES-F8) manufactured by Kato Tech Co., Ltd. or an equivalent gas permeability tester, set the standard air permeability speed to 2 cm / s and measure the air permeability resistance value of the sample. 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.

[0176] Figure 12 It is a diagram for explaining the sanitary napkin 100 which is a modification of the first embodiment. It can also be as Figure 12The 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, the sanitary napkin 1 has side flaps 5, but it may not necessarily have side flaps 5 as in the case of the sanitary napkin 100.

[0177] 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 holding liquid (excrement) in the voids formed by the fibers 2f. The backsheet 4 is a liquid-impermeable sheet material as described above.

[0178] The skin-side layer 2 (absorbent layer 10) of the sanitary napkin 100 is a layer capable of absorbing and holding liquid. Figure 13 It is a schematic cross-sectional view showing the crotch region M of the skin-side layer 2. 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.

[0179] In the crotch region M of the sanitary napkin 100 having this skin-side layer 2, a desired absorption function is provided. The "crotch region" is the region located in the crotch of the wearer in the worn state, and the crotch region M of the sanitary napkin 100 is the central portion in the length direction. For example, in the sanitary napkin 100 without wing portions 1w, the central region when the length H100 of the sanitary napkin 100 in the length direction is divided into three equal parts can be the crotch region M.

[0180] Regarding the crotch region M of the sanitary napkin 100, when the weight of the crotch region M before absorbing distilled water is set as the pre-absorption weight (a), and the weight of the crotch region M after immersing it 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 (A), and when the value obtained by subtracting the pre-absorption weight (a) from the post-absorption weight (A) is set as the absorption weight (b) of distilled water (b = A - a), the value obtained by dividing the absorption weight (b) by the pre-absorption weight (a) is 5 or more (b / a ≥ 5).

[0181] In addition, in the thickness direction of the absorbent layer 10 in the crotch region M, the side in contact with the skin of the wearer is the skin side, and the opposite side of the skin side is the non-skin side. As Figure 13 shown, the absorbent layer 10 (skin-side layer 2) is divided into three equal parts 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, and the region between the skin-side region Ru and the non-skin side region Rd is set as the intermediate region Rm. Regarding the voids formed by the fibers 2f in the skin-side layer 2, the narrowness of the voids in the non-skin side region Rd is narrower than the narrowness of the voids in the skin-side region Ru.

[0182] Further, the bending hysteresis 2HB of the crotch region M based on the KES method is 3.5 gf·cm 2 / cm or less.

[0183] The larger the value obtained by dividing the absorption weight b by the weight a before absorption, the more distilled water the sanitary napkin 100 can absorb, 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 100 can sufficiently ensure the function of absorbing liquid. In addition, the absorbed liquid can be retained within the skin-side layer 2.

[0184] In addition, regarding the voids formed by the fibers 2f, the narrowness of the voids in the non-skin-side region Rd is narrower than the narrowness of the voids in the skin-side region Ru. Thus, in the worn state, it is easy to introduce the excrement received by the skin side surface of the skin-side region Ru in the skin-side layer 2 toward the non-skin-side region Rd by capillary action. In addition, it is easy to spread the excrement introduced into the non-skin-side region Rd over a larger range within the non-skin-side region Rd. Thereby, it is possible to reduce the situation where the excrement absorbed from the skin side surface of the skin-side region Ru stays on the skin side surface of the skin-side region Ru or within the skin-side region Ru, and it is possible to reduce the concern that discomfort or skin roughness may easily occur due to the excrement continuously contacting 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 Ru toward the non-skin-side region Rd, and thus it is possible to reduce the concern that the excrement flows along the surface of the skin-side region Ru and leaks from the sanitary napkin 100.

[0185] Furthermore, compared with the case where the bending hysteresis 2HB based on the KES method of the central portion in the length direction and the central portion in the width direction of the skin-side layer 2 is greater than 3.5 gf·cm 2 / cm, by setting the bending hysteresis 2HB based on the KES method of the central portion in the length direction and the central portion in the width direction of the skin-side layer 2 (absorbent layer 10) to 3.5 gf·cm 2 / cm or less, the restorability of the crotch region M can be made good in the worn state. Even when the skin-side layer 2 is deformed due to an external force generated by the shape and movement of the wearer's body, it is easy for the skin-side layer 2 to return to its original shape, and it is possible to reduce the discomfort caused by the deformation of the skin-side layer 2 in the crotch region M, or it is easy for the skin-side layer 2 to follow the wearer's body and movement, thereby improving the comfort during wearing.

[0186] The non-woven fabric sheet of the skin side layer 2 of the sanitary napkin 100 is formed by the above-described hydroentangling method. During its formation, by pouring water from the skin side toward the non-skin side, it becomes easy to press the fibers 2f from the skin side toward the non-skin side. Thus, the narrowness of the voids in the non-skin side region Rd is narrower than the narrowness of the voids in the skin side region Ru, but it is not limited thereto. For example, the thickness (fiber diameter) of the fibers in the non-skin side region Rd may be thinner than the thickness (fiber diameter) of the fibers in the skin side region Ru. Additionally, it may be that potential crimp fibers having a stronger crimp property than the fibers used for the skin side region Ru are used for the fibers in the non-skin side region Rd to make the narrowness of the voids in the non-skin side region Rd narrower than the narrowness of the voids in the skin side region Ru.

[0187] In addition, the measurement of the absorption function, the comparison of the narrowness of the voids, and the measurement of the bending hysteresis amount HB in the KES method can be respectively carried out using the above-described measurement methods.

[0188] ===Second Embodiment ===

[0189] <<<Structure of Sanitary Napkin 300>>>

[0190] Figure 14 is a top view obtained by observing the sanitary napkin 300 (hereinafter also referred to as "sanitary napkin 300") from the skin side. Figure 15 is a diagram for explaining the structure of the sanitary napkin 300. Figure 15 is a schematic view showing the components of the sanitary napkin 300 disassembled in the thickness direction, and the detailed structure such as the adhesive for fixing the components to each other and the thickness of each component is omitted. Additionally, some structures of the above-described sanitary napkin 1 can also be applied to the following sanitary napkin 300.

[0191] The sanitary napkin 300 has a length direction, a width direction, and a thickness direction that are orthogonal to each other. In the length direction, the side that abuts against the wearer's lower abdomen is set as the front side, and the side that abuts against the wearer's buttocks is set as the rear side. In the thickness direction, the side that abuts against the wearer's skin is the skin side, and the opposite side is the non-skin side. Figure 14 The shown center line C-C represents the center in the width direction of the sanitary napkin 300, and the center line CL represents the center in the length direction of the sanitary napkin 300. The outer shape of the sanitary napkin 300 in this embodiment is symmetric in the length direction (symmetric with respect to the center line CL) and symmetric in the width direction (symmetric with respect to the center line C-C).

[0192] As Figure 14 and Figure 15As shown, the sanitary napkin 300 has a topsheet 31 positioned on the side closest to the skin, a second sheet 32, a liquid-absorbing member 33 capable of absorbing liquid, and a backsheet 34 positioned on the side farthest from the skin. Each material adjacent to each other in the thickness direction is joined by an adhesive such as hot melt adhesive.

[0193] The topsheet 31 is a liquid-permeable sheet material positioned on the side closer to the skin than the absorbent member 33. As the topsheet 31, examples include cotton, a fabric made of synthetic fibers such as polyethylene (PE) and polypropylene (PP), a non-woven fabric, a thermoplastic film or synthetic resin film having through-holes, and a soft sheet material such as a polymer material formed of a foam such as a water-foamed thermoplastic film.

[0194] The second sheet 32 is a sheet material positioned on the side closer to the skin than the absorbent member 33 and on the side farther from the skin than the topsheet 31. As the second sheet 32, examples include a non-woven fabric or fabric containing synthetic fibers of polyester, polypropylene or polyethylene, natural fibers containing cotton or cellulose, or a mixture of the above fibers.

[0195] The backsheet 34 is a sheet material positioned on the side farther from the skin than the absorbent member 33. As the backsheet 34, examples include a resin film of polyethylene or polypropylene, or a liquid-impermeable sheet material such as a fabric or non-woven fabric formed by film coating.

[0196] The absorbent member 33 is an absorber (absorbent layer) having a liquid absorption function and a liquid retention function and having a predetermined thickness. The absorbent member 33 is a polymer foam capable of absorbing liquid. The polymer foam is a polymer foam material having a hydrophilic soft non-ionic polymer foam structure, and the non-ionic polymer foam structure has a plurality of interconnected pores h. Figure 16 It is a schematic diagram for explaining a partial enlargement of the absorbent member 33. By liquid (excrement) entering the pores h of the absorbent member 33, a state in which the absorbent member 33 absorbs and retains the liquid can be formed.

[0197] The polymer foam constituting the absorbent member 33 is formed by polymerizing an oil phase component and a water phase component at a specified ratio and under specified conditions and then performing a dehydration treatment. Examples of the oily component include monofunctional monomers such as isodecyl acrylate that can form an atactic amorphous polymer having a solid foam structure by polymerization, and monofunctional copolymer monomers based on styrene such as styrene and ethyl styrene. The oily component contains a polyfunctional crosslinking agent such as divinylbenzene and an emulsifier. Examples of the water phase component include water-soluble electrolytes such as alkali metal chlorides, and the water phase component contains a polymerization initiator.

[0198] In the crotch region M of the sanitary napkin 300 having the absorbent member 33, the desired absorption function is provided. The "crotch region" is the region located in the crotch of the wearer in the worn state, and the crotch region M of the sanitary napkin 300 is the central portion in the longitudinal direction. For example, as in the sanitary napkin 300 of the present embodiment, in the case of not having the wings 1w, the central region when the length H300 of the sanitary napkin 300 in the longitudinal direction is divided into three equal parts can be the crotch region M. In addition, in the case of having wings, the region overlapping the wings in the longitudinal direction is set as the crotch region.

[0199] Regarding the crotch region M of the sanitary napkin 300, when the weight of the crotch region M before absorbing distilled water is set as the pre-absorption weight (a), and the weight of the crotch region M after immersing the crotch region M 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 (A), and when the value obtained by subtracting the pre-absorption weight (a) from the post-absorption weight (A) is set as the absorption weight (b) of distilled water (b = A - a), the value obtained by dividing the absorption weight (b) by the pre-absorption weight (a) is 5 or more (b / a ≥ 5).

[0200] In addition, in the thickness direction of the absorbent member 33 in the crotch region M, the side in contact with the skin of the wearer is the skin side, and the opposite side of the skin side is the non-skin side. The absorbent member 33 is divided into three equal parts in the thickness direction, 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. For the pore h of the absorbent member 33, the narrowness of the pore h in the non-skin side region is narrower than the narrowness of the pore h in the skin side region.

[0201] And, the bending hysteresis amount 2HB based on the KES method of the crotch region M is 3.5 gf·cm 2 / cm or less.

[0202] The larger the value obtained by dividing the absorption weight b by the pre-absorption weight a, the more the sanitary napkin 300 can absorb more distilled water, and thus can absorb more excrement. Compared with the case where the value obtained by dividing the absorption weight b by the pre-absorption weight a is less than 5, by setting the value obtained by dividing the absorption weight b by the pre-absorption weight a to 5 or more, the sanitary napkin 300 can sufficiently ensure the function for absorbing liquid.

[0203] In addition, regarding the pores h of the absorption member 33, the narrowness of the pores h in the non-skin side region is narrower than that of the pores h in the skin side region. Thus, in the worn state, it is easy to introduce excrement received by the skin side surface of the skin side region in the absorption member 33 into the non-skin side region by capillary action. In addition, it is easy to make the excrement introduced into the non-skin side region diffuse within a larger range in the non-skin side region. Thereby, it is possible to reduce the situation where the excrement absorbed from the skin side surface of the skin side region stays on the skin side surface and within the skin side region, and it is possible to reduce the concern that discomfort and skin roughness are likely to be caused due to 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 to the non-skin side region, and thus it is possible to reduce the concern that the excrement flows along the surface of the skin side region and leaks from the sanitary napkin 300.

[0204] Furthermore, compared with the case where the bending hysteresis amount 2HB based on the KES method of the central portion in the length direction and the central portion in the width direction of the absorption member 33 is greater than 3.5 gf·cm 2 / cm, by setting the bending hysteresis amount 2HB based on the KES method of the central portion in the length direction and the central portion in the width direction of the absorption member 33 to 3.5 gf·cm 2 / cm or less, the restorability of the crotch region M in the worn state can be made good. Even when the absorption member 33 is deformed due to an external force generated by the shape and movement of the wearer's body, it is easy for the absorption member 33 to return to its original shape, and it is possible to reduce the discomfort caused by the deformation of the absorption member 33 in the crotch region M, or it is easy for the absorption member 33 to follow the wearer's body and movement, thereby improving the comfort during wearing.

[0205] In addition, the comparison of the narrowness of the pores h can be carried out by the same method as the comparison of the narrowness of the voids in the first embodiment. In addition, the measurement of the absorption function and the measurement of the bending hysteresis amount HB in the KES method can be carried out by the above-mentioned measurement methods respectively.

[0206] The sanitary napkin 300 is not limited to this structure. For example, it can also be a structure without the second sheet 32, and the sanitary napkin 300 can also be a structure with wing parts, side sheets, compression parts, slits, leak-proof wall parts, etc. In addition, the absorbent member 33 can also be a multi-layer absorbent body having two or more layers of absorbent bodies (a structure in which polymer foams are overlapped two or more layers). For example, in the case where the absorbent member 33 has a structure of two absorbent bodies, the narrowness (size) of the pores h of the absorbent body (polymer foam) on the non-skin side is made smaller than the narrowness (size) of the pores h of the absorbent body (polymer foam) on the skin side, whereby it is easy to move excrement (liquid) in the absorbent member 33 from the skin side toward the non-skin side by capillary action.

[0207] ===Other Embodiments===

[0208] The above-described embodiments are for easily understanding the present invention and are not for limitatively interpreting 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.

[0209] Explanation of Reference Numerals

[0210] 1, 100, 300, sanitary napkin (sanitary napkin for menstruation, absorbent article); 1w, wing part; 2, skin-side layer; 2f, latent crimp fiber (fiber); 3, non-skin-side layer; 3f, latent crimp fiber (fiber); 4, back sheet; 5, side sheet; 10, absorbent layer; 20, compression part; 31, top sheet; 32, second sheet (absorbent core); 33, absorbent member (absorbent layer); 34, back sheet; DH, high-density part; DL, low-density part; M, crotch region; Ru, skin-side region (absorbent side region); Rm, intermediate region; Rd, non-skin-side region (non-absorbent side region).

Claims

1. An absorbent article which, in an unfolded state, has a length direction, a width direction, and a thickness direction, and includes an absorbent layer capable of absorbing liquid, characterized in that: the absorbent layer is a nonwoven fabric having voids formed by a plurality of fibers, or a polymer foam having a plurality of pores; in a crotch region that is located at the crotch of the wearer when worn; the weight of the crotch region before absorbing distilled water is defined as the pre-absorption weight; the weight of the crotch region after dipping the crotch region 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 pre-absorption weight is 5 or more; when the absorbent layer is trisected in the thickness direction, the region closest to the skin side is defined as the skin-side region, the region closest to the non-skin side is defined as the non-skin side region, and the region between the skin-side region and the non-skin side region is defined as the intermediate region, the narrowness of the voids or pores in the non-skin side region is narrower than the narrowness of the voids or pores in the skin-side region; The bending hysteresis 2HB in the KES method for the crotch region is 3.5 gf·cm 2 / cm or less.

2. The absorbent article according to claim 1, characterized in that: the hydrophilicity of the skin-side region is lower than the hydrophilicity of the non-skin side region.

3. The absorbent article according to claim 1 or 2, characterized in that: a preparation for improving hydrophilicity is provided at least in the non-skin side region.

4. The absorbent article according to claim 1 or 2, characterized in that: The bending stiffness B in the KES method of the crotch region of the absorbent layer is 2.0 gf·cm 2 / cm or less.

5. The absorbent article according to claim 1 or 2, characterized in that: the thickness of the absorbent layer is 4 mm or less.

6. The absorbent article according to claim 1 or 2, characterized in that: the absorbent layer is provided with a deformation guiding portion for guiding deformation.

7. The absorbent article according to claim 1 or 2, characterized in that: in a ratio evaluation test for quantitatively evaluating the ratio of the voids or pores in a predetermined region of the absorbent layer, the ratio of the voids or pores in the non-skin side region in the ratio evaluation test is smaller than the ratio of the voids or pores in the skin-side region in the ratio evaluation test.

8. The absorbent article according to claim 1 or 2, characterized in that: the linearity LC of the compression characteristics in the KES method of the crotch region of the absorbent layer is 0.6 or more.

9. The absorbent article according to claim 1 or 2, characterized in that: the compression resilience RC of the crotch region of the absorbent layer in the KES method is 38% or more.

10. The absorbent article 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 absorbent layer to 1.3 times the length in the length direction of the absorbent layer, the value obtained by dividing the magnitude of the force measured in the 10th measurement of the elongation test of the absorbent layer by the magnitude of the force measured in the 1st measurement of the elongation test of the absorbent layer is 50% or more.

11. The absorbent article according to claim 1 or 2, characterized in that the air permeability resistance value of the absorbent layer is 0.32 kpa·s / m or less.

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