Absorbent article

Abstract

The absorbent article is characterized in that the surface sheet (20) has a skin-side part (21) and a non-skin-side part (22), the average fineness of fibers constituting the non-skin-side part (22) is smaller than the average fineness of fibers constituting the skin-side part (21), the absorbent core (121) has a compressed part (123) compressed from the skin side in the thickness direction, and when a drainage test is performed, the drainage index is 50% or less. In a liquid discharge test, 40 ml of artificial urine is dropped four times at a predetermined position on the surface sheet (20), and then a liquid discharge index related to the absorption rate and the absorption amount of the artificial urine is obtained on the basis of the measurement results of the predetermined position by a moisture meter.

Description

TECHNICAL FIELD

[0001] The present application relates to an absorbent article. BACKGROUND

[0002] In the absorbent body of the disposable diaper of Patent Literature 1, a non-fleece portion extending in the longitudinal direction is formed. Therefore, the non-fleece portion becomes a deformation starting point, and the absorbent body is fitted to the wearer's body. Further, by providing the surface sheet in the non-fleece portion, the formation of a space between the surface sheet and the absorbent body is limited, and the liquid discharged to the non-fleece portion is smoothly transferred to the lower side in the thickness direction.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2016-30109 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, in Patent Literature 1, in order to provide the surface sheet in the non-fleece portion (in order to press the surface sheet into the non-fleece portion), the fineness of the fibers of the lower layer of the surface sheet is made higher than that of the upper layer of the surface sheet, the binding points of the fibers to each other are made sparse, and the lower layer is easily elongated. In this case, the gaps between the fibers of the lower layer of the surface sheet are larger than the gaps between the fibers of the upper layer. Therefore, the capillary phenomenon from the upper layer to the lower layer of the surface sheet does not work, and the introduction of the discharged liquid into the inside of the surface sheet is not good. Therefore, the liquid easily remains on the surface sheet, and the dryness on the surface sheet cannot be sufficiently obtained.

[0008] The present application has been achieved in view of the above-described problems, and an object thereof is to provide an absorbent article in which the dryness on the surface sheet (skin side) is improved.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The main invention for achieving the above-mentioned objective is an absorbent article having mutually orthogonal length, width, and thickness directions in its unfolded state, and having an absorbent core and a surface sheet. The surface sheet is characterized by having a skin-side portion located on the skin side in the thickness direction and a non-skin-side portion located on the non-skin side in the thickness direction, the average fineness of the fibers constituting the non-skin-side portion being smaller than the average fineness of the fibers constituting the skin-side portion. The absorbent core has a compression portion formed by compression from the skin side in the thickness direction. When a drainage test is performed, the drainage index is less than 50%. In the drainage test, after four drops of 40 ml of artificial urine were applied to a predetermined position on the surface sheet, the drainage index, related to the absorption rate and amount of the artificial urine, is determined based on measurements taken at the predetermined position using a moisture meter.

[0011] Other features of the invention will become clear from the description in this specification and the accompanying drawings.

[0012] The effects of the invention

[0013] According to the present invention, it is possible to provide an absorbent article that improves the dryness of the surface sheet (skin side). Attached Figure Description

[0014] Figure 1 This is a rough 3D diagram of Diaper 1.

[0015] Figure 2 This is a rough top view of the diaper 1 in its unfolded and stretched state, viewed from the skin side.

[0016] Figure 3 yes Figure 2 A rough cross-sectional view at line AA.

[0017] Figure 4 yes Figure 2 A schematic cross-sectional view at the center line CL.

[0018] Figure 5 of Figure 5 A is a schematic cross-sectional view of surface piece 20. Figure 5 B is a top view obtained by observing surface piece 20 from the skin side.

[0019] Figure 6 of Figure 6 A is an explanatory diagram of the fibers constituting the surface sheet 20. Figure 6 B is an explanatory diagram of the surface piece 20 when worn.

[0020] Figure 7 of Figure 7 A and Figure 7B is a top view obtained by observing the absorber 12 from the skin side.

[0021] Figure 8 of Figure 8 A and Figure 8 B is an explanatory diagram of the compression section 123.

[0022] Figure 9 This is a graph showing the results of the drainage test.

[0023] Figure 10 of Figure 10 A and Figure 10 B is a graph representing the results of the drainage test.

[0024] Figure 11 This is an explanatory diagram of the fixture 50 for setting diaper 1.

[0025] Figure 12 of Figure 12 A and Figure 12 B is an explanatory diagram of a modified example of surface sheet 20. Detailed Implementation

[0026] Based on the description in this specification and the accompanying drawings, at least the following matters become clear.

[0027] (Method 1)

[0028] An absorbent article, in its unfolded state having mutually orthogonal length, width, and thickness directions, and comprising an absorbent core and a surface sheet, characterized in that the surface sheet has a skin-side portion located on the skin side in the thickness direction and a non-skin-side portion located on the non-skin side in the thickness direction beyond the skin-side portion, the average fineness of the fibers constituting the non-skin-side portion being smaller than the average fineness of the fibers constituting the skin-side portion, the absorbent core having a compression portion formed by compression from the skin side in the thickness direction, and a drainage index of 50% or less when a drainage test is performed, wherein in the drainage test, after four drops of 40 ml of artificial urine are applied to a predetermined position on the surface sheet, the drainage index, related to the absorption rate and absorption volume of the artificial urine, is determined based on the measurement results of a moisture meter at the predetermined position.

[0029] According to Method 1, compared to the skin-side surface, the gaps between fibers on the non-skin-side surface are smaller, allowing excretion fluid to easily transfer from the skin-side surface to the non-skin-side surface. Excretion fluid further transferred to the skin-side surface of the absorbent core is easily introduced into the interior of the absorbent core through the compression section with higher fiber density. Therefore, excretion fluid is less likely to remain on the surface sheet, improving its dryness. Furthermore, compared to cases where the excretion index is higher than 50%, the absorption rate and amount of excretion fluid on the surface sheet are increased, further improving its dryness.

[0030] (Method 2) For the absorbent article described in Method 1, the characteristic is that the tensile strength in the length direction of the skin side of the surface sheet is higher than the tensile strength in the length direction of the non-skin side.

[0031] According to method 2, when pressure is applied from the wearer's body, the non-skin side is easily flattened, and the gaps between the fibers on the non-skin side become smaller. Therefore, excrement easily transfers from the skin side to the non-skin side. On the other hand, the skin side is not easily flattened, ensuring thickness (volume), so the excrement absorbed by the absorbent core is less likely to flow back onto the surface sheet, improving the dryness of the surface sheet and making it easier to maintain that dryness.

[0032] (Method 3) For the absorbent article described in Method 1 or Method 2, the characteristic is that the total length of the fibers constituting the non-skin side of the surface sheet is longer than the total length of the fibers constituting the skin side.

[0033] According to method 3, when pressure is applied from the wearer's body, the gaps between more fibers narrow, thus facilitating the transfer of excretory fluid from the skin side to the non-skin side. Therefore, the dryness of the surface sheet is improved.

[0034] (Method 4) For any of the absorbent articles described in Methods 1 to 3, the absorbent article is characterized in that the absorbent article has a sheet adjacent to the surface sheet on the non-skin side in the thickness direction, and the hydrophilicity of the skin side of the sheet is higher than that of the skin side of the surface sheet.

[0035] According to method 4, the excretion fluid transferred from the skin-side of the surface sheet to the non-skin-side is more easily transferred to the sheet with higher hydrophilicity. Therefore, the excretion fluid sequentially transfers into the interior of the absorbent material, making it less likely for the excretion fluid to remain on the surface sheet, thus improving the dryness of the surface sheet.

[0036] (Method 5) For any of the absorbent articles described in Method 1 to Method 4, the surface sheet is not compressed in the compression section.

[0037] According to method 5, a gap can easily be formed between the surface sheet and the absorbent core. The excreted liquid absorbed by the absorbent core can be easily stored temporarily in this gap and is less likely to flow back onto the surface sheet. Therefore, it is easy to maintain the dryness of the surface sheet.

[0038] (Method 6) For the absorbent article described in Method 5, the characteristic is that a plurality of protrusions extending along the length direction are arranged at intervals in the width direction on the skin side of the surface sheet.

[0039] According to method 6, the contact area between the surface sheet and the wearer can be reduced, making it less likely for the wearer to feel the moisture in the absorbent material, thus improving wearing comfort. In addition, when the user touches the surface sheet to check its dryness, the fingertip can easily move smoothly along the length, making it easier for the user to recognize that this is a product with high dryness on the surface sheet.

[0040] (Method 7) For any of the absorbent articles described in Method 1 to Method 4, the surface sheet and the absorbent core are compressed together in the compression section.

[0041] According to method 7, the excrement flowing into the high-density compression section is easily introduced from the surface sheet to the absorbent core via capillary action. Furthermore, due to the improved visual visibility of the compression section, users can easily recognize that this is a product where the excrement is easily absorbed.

[0042] (Method 8) For any of the absorbent articles described in Method 1 to Method 7, the surface sheet is characterized in that the surface sheet has a through hole extending along the thickness direction of the surface sheet.

[0043] According to method 8, the excrement flows down from the through holes of the surface sheet into the interior of the absorbent material, thus increasing the absorption rate of the excrement on the surface sheet and improving the drying properties of the surface sheet.

[0044] (Method 9) For an absorbent article described in any of Methods 1 to 8, the skin side of the surface sheet is characterized in that the surface sheet has a high weight-per-unit area region where the fiber has a higher weight-per-unit area and a low weight-per-unit area region where the fiber has a lower weight-per-unit area than the high weight-per-unit area region.

[0045] According to method 9, the local thickness or density of the skin side can be increased by utilizing the high weight-per-unit area region. By increasing the thickness (volume) of the high weight-per-unit area region, the backflow of excretory fluid can be suppressed. In addition, by increasing the density of the high weight-per-unit area region, it is easier to utilize capillary action to introduce excretory fluid from the surface plate inward.

[0046] (Method 10) For the absorbent article described in Method 9, the high weight-per-unit area region protrudes towards the skin side more than the low weight-per-unit area region.

[0047] According to method 10, unevenness can be formed on the skin-friendly side of the surface sheet, reducing the contact area between the surface sheet and the wearer. Therefore, the wearer is less likely to feel moisture from the absorbent material, improving wearing comfort.

[0048] (Method 11) For the absorbent article described in any of Methods 1 to 10, the characteristic is that when a test for measuring the amount of moisture return is performed, the amount of moisture return is less than 1.0g, and the test for measuring the amount of moisture return is a test that measures the amount of moisture return of the artificial urine that returns to the surface sheet after 40ml of artificial urine has been added to the surface sheet four times.

[0049] According to method 11, compared with the case where the amount of re-moistening is more than 1.0g, it can suppress the return of the excreted liquid absorbed by the absorbent core to the surface sheet, and maintain the dryness of the surface sheet.

[0050] ===Implementation Methods===

[0051] As an absorbent article of the present invention, a disposable diaper 1 (hereinafter also referred to as "diaper 1") of the underwear type for infants and young children will be used as an example for description. However, the absorbent articles of the present invention also include strip-type disposable diapers, panty-type sanitary napkins, absorbent pads, menstrual sanitary napkins, and other absorbent articles. In addition, the wearer of the absorbent article is not limited to infants and young children, but can also be adults or animals.

[0052] <Structure of Diaper 1>

[0053] Figure 1 This is a rough 3D diagram of Diaper 1. Figure 2 This is a rough top view of the diaper 1 in its unfolded and stretched state, viewed from the skin side. Figure 3 yes Figure 2 A rough cross-sectional view at line AA. Figure 4 yes Figure 2 A schematic cross-sectional view at the center line CL.

[0054] The "stretched state" of diaper 1 refers to the state in which diaper 1 is stretched out to the point of being wrinkle-free. Specifically, it refers to the state in which the dimensions of each component constituting diaper 1 (such as the absorbent body 10, waist section 30, 40, etc., described later) are the same as or close to the dimensions of a single component. The "unfolded state" of diaper 1 refers to the state in which the diaper 1 is opened and unfolded in a flat plane by separating the pair of side joints 2 located on both sides of diaper 1.

[0055] The diaper 1 has mutually orthogonal vertical, width, and front-back directions, and has a waist opening BH and a pair of leg openings LH. The upper side of the vertical direction corresponds to the side of the waist opening BH, and the lower side corresponds to the crotch side. The front side of the front-back direction corresponds to the wearer's abdomen, and the back side corresponds to the wearer's back. The width direction is along the stretching direction of the elastic band 33 of the front waist section 30 and the elastic band 43 of the back waist section 40. The vertical direction is along a direction orthogonal to the stretching direction.

[0056] Diaper 1 is a so-called three-piece pant-type diaper having a liquid-absorbing absorbent body 10 and a pair of waist sections 30, 40. The portion of the pair of waist sections that covers the wearer's ventral side is also referred to as the front waist section 30, and the portion of the pair of waist sections that covers the wearer's dorsal side is also referred to as the back waist section 40.

[0057] exist Figure 2 In its unfolded state, the diaper 1 has mutually orthogonal length, width, and thickness directions. The length direction is along the length of the absorbent body 10 and along the vertical direction of the panty-type diaper 1. For example... Figure 3 As shown, the thickness direction is the direction in which the materials constituting the diaper 1 are layered. The side in contact with the wearer's skin in the thickness direction is designated as the skin side, and the opposite side is designated as the non-skin side. Furthermore, in the unfolded state, with the front waist section 30 and the back waist section 40 arranged parallel to each other at intervals in the length direction, an absorbent body 10 is positioned between them, and each end of the absorbent body 10 in the length direction is respectively joined and fixed to the skin side of the closest waist sections 30 and 40, resulting in an approximate letter H shape when viewed from above. Then, from this state, the diaper 1 is folded in half at the center line CL in the length direction. In this folded state, the opposing front waist sections 30 and back waist sections 40 are joined and connected at their sides in the width direction, thereby forming a pair of side joints 2. Moreover, the side joints 2 are formed using known joining methods such as welding and bonding.

[0058] The absorbent body 10 has an absorbent body 12, a liquid-permeable surface sheet 20 disposed on the skin side of the absorbent body 12, and a back sheet 13 disposed on the non-skin side of the absorbent body 12. The back sheet 13 has a double-layer structure consisting of a liquid-impermeable sheet 13a and a hydrophobic outer sheet 13b disposed on the non-skin side of the liquid-impermeable sheet 13a. However, the absorbent body 10 may also have sheet components other than those described above. For example, a second sheet (not shown) may be provided between the surface sheet 20 and the absorbent body 12 in the thickness direction.

[0059] The absorbent body 12 has an absorbent core 121 and a core sheet 122 covering the outer peripheral surface of the absorbent core 121. The absorbent core 121 is a component that absorbs and retains excretory fluids such as urine, and is formed, for example, from liquid-absorbent fibers such as pulp fibers mixed with superabsorbent polymers (SAP). As the core sheet 122, liquid-permeable sheet components such as cotton paper and non-woven fabrics can be exemplified.

[0060] A pair of leak-proof wall portions 15 are provided on both sides of the absorbent body 10 in the width direction and along the length direction of the absorbent body 10. Figure 4In the middle, in the width direction, a portion of the outer sheet 13b extends to a position further outward than both ends of the absorbent body 20, and is bent towards the skin at multiple locations, thereby forming a pair of leak-proof wall portions 15. Leak-proof wall elastic members 16, such as elastic bands, are installed at the ends of the leak-proof wall portions 15 in a state that extends along the length direction of the absorbent body 10, and the leak-proof wall portions 15 are configured to stand upright towards the skin.

[0061] In addition, elastic members 17 such as elastic bands are installed on both sides of the absorbent body 10 in the width direction, extending along the length direction of the absorbent body 10.

[0062] The front waist section 30 has skin-friendly side panels 31, non-skin-friendly side panels 32, and multiple elastic waistbands 33, while the rear waist section 40 has skin-friendly side panels 41, non-skin-friendly side panels 42, and multiple elastic waistbands 43. The multiple elastic waistbands 33 are arranged vertically and extended in the width direction between the skin-friendly side panels 31 and the non-skin-friendly side panels 32. Similarly, the multiple elastic waistbands 43 are arranged vertically and extended in the width direction between the skin-friendly side panels 41 and the non-skin-friendly side panels 42. The front waist section 30 conforms to the wearer's waist using the elasticity of the elastic waistbands 33, and the rear waist section 40 conforms to the wearer's waist using the elasticity of the elastic waistbands 43.

[0063] Alternatively, covers 34 and 44 can be provided to cover the upper part of the absorbent body 10 from the skin side. Covers 34 and 44 can be used to suppress openings in the absorbent body 10. Alternatively, a printed sheet 35 with a pattern printed on it can be provided between the skin-side sheet 31 and the non-skin-side sheet 32, and a printed sheet 45 with a pattern printed on it can be provided between the skin-side sheet 41 and the non-skin-side sheet 32.

[0064] In addition, such as Figure 3 As shown, the front waist section 30 and the rear waist section 40 have different planar shapes when unfolded and extended. The front waist section 30 is a rectangular shape with a length in the vertical direction approximately the same as the side joint 2 and a longer length in the width direction. The rear waist section 40 has a rectangular portion that overlaps with the front waist section 30 and a roughly trapezoidal portion 40E that extends downward beyond that portion. This extended portion 40E can cover the wearer's buttocks.

[0065] The basic structure of diaper 1 has been described above, but the structure described above is an example and is not limited thereto. For example, the front waist section 30 and the back waist section 40 may be formed by a continuous single member, or an external member may be provided in the crotch area to connect the front waist section 30 and the back waist section 40. In addition, the elastic members such as waist elastic members 33 and 43 may not be elastic bands, but sheet-like elastic members.

[0066] ===Drying properties on surface sheet 20===

[0067] Figure 5 A is a schematic cross-sectional view of surface piece 20. Figure 5 B is a top view obtained by observing surface piece 20 (partial) from the skin side. Figure 6 A is an explanatory diagram of the fibers constituting the surface sheet 20. Figure 6 B is an explanatory diagram of the surface piece 20 when worn. Figure 7 A and Figure 7 B is a top view obtained by observing the absorber 12 from the skin side. Figure 8 A and Figure 8 B is an explanatory diagram of the compression section 123. Figure 9 , Figure 10 A and Figure 10 B is a graph representing the results of the drainage test.

[0068] like Figure 6 As shown in Figure A, the surface sheet 20 has a skin-side portion 21 located on the skin side in the thickness direction and a non-skin-side portion 22 located on the non-skin side in the thickness direction beyond the skin-side portion 21. Furthermore, as... Figure 5 As shown in Figure A, the surface sheet 20 in this embodiment is a sheet material that has been shaped with concave and convex features. However, for ease of understanding of the drawings, in... Figure 6 A and Figure 6 In diagram B, surface piece 20 is shown as flat.

[0069] like Figure 6As shown in Figure A, the average fineness of the fibers f2 constituting the non-skin side 22 of the surface sheet 20 is smaller than the average fineness of the fibers f1 constituting the skin side 21 of the surface sheet 20. In other words, the fibers f2 constituting the non-skin side 22 are finer than the fibers f1 constituting the skin side 21. Therefore, in the skin side 21, it is difficult for further fibers f1 to enter between the fibers f1, and the fibers f1 exist sparsely. In contrast, in the non-skin side 22, it is easy for further fibers f2 to enter between the fibers f2, and the fibers f2 exist densely. Consequently, the gaps g2 between the fibers f2 constituting the non-skin side 22 are smaller than the gaps g1 between the fibers f1 constituting the skin side 21. Therefore, excretory fluids such as urine excreted onto the surface sheet 20, after penetrating the skin side 21, are easily transferred to the non-skin side 22 via capillary action. In other words, excretory fluids are easily introduced into the interior of the surface sheet 20.

[0070] Furthermore, the comparison of the average fineness of fibers f1 and f2 can be performed using known methods. For example, after freezing the surface sheet 20 of the object using liquid nitrogen or the like, fibers of a predetermined length (e.g., 5 mm) are cut from 10 arbitrary locations on both the skin side 21 and the non-skin side 22. That is, fibers are cut from both the skin side and the non-skin side of the surface sheet 20. The ends of the cut fibers are cut at right angles relative to the fiber's extension direction. The cut surface is photographed at a predetermined magnification, and the fiber diameter (mm) is measured based on the obtained cross-sectional photograph. The average fiber diameter of the 10 fibers taken from the skin side 21 (skin side) is calculated, and the average fiber diameter of the 10 fibers taken from the non-skin side 22 (non-skin side) is also calculated. When the average fiber diameter of the non-skin side 22 is smaller than the average fiber diameter of the skin side 21, it can be confirmed that the average fineness of the fiber f2 constituting the non-skin side 22 is smaller than the average fineness of the fiber f1 constituting the skin side 21.

[0071] Furthermore, the portion of the surface sheet 20 composed of fibers f1 with a relatively large average fiber diameter is designated as the skin side 21, and the portion of the surface sheet 20 composed of fibers f2 with a relatively small average fiber diameter is designated as the non-skin side 22. The thickness of the skin side 21 and the non-skin side 22 can be the same or different. In addition, at the boundary between the skin side 21 and the non-skin side 22, the coarser fibers f1 and the finer fibers f2 are mixed together. Therefore, taking the center position in the thickness direction of the region where fibers of different thicknesses are mixed as the boundary, the portion closer to the skin side than this boundary is designated as the skin side 21, and the portion closer to the non-skin side than this boundary is designated as the non-skin side 22.

[0072] Furthermore, it is preferable that the fibers f1 constituting the skin side 21 and the fibers f2 constituting the non-skin side 22 are thermoplastic fibers. In this case, during the manufacturing process of the surface sheet 20, heat is applied to the stacked fibers (fiber web), thereby causing the fibers to be locally thermally fused together to form a sheet.

[0073] Examples of thermoplastic fibers include fibers formed from polyolefin polymers such as polyethylene and polypropylene, polyester polymers such as polyethylene terephthalate (PET), polybutylene terephthalate, and polypentyl terephthalate, polyamide polymers such as nylon 6 and nylon 66, acrylic polymers, polyacrylonitrile polymers, or modified forms thereof, or combinations thereof.

[0074] In addition, such as Figure 7 and Figure 8 As shown, the absorbent core 121 has a compression portion 123 formed by compression from the skin side in the thickness direction. The compression portion 123 is not a portion formed by compressing the entire planar area of ​​the absorbent core 121 (so-called flat compression), but rather a portion formed by locally compressing the absorbent core 121. Furthermore, in Figure 8 The same applies to surface sheet 20. For ease of understanding, the accompanying drawings do not show a convex or concave shape, but rather a flat shape.

[0075] In the compression section 123, the absorbent core 121 is recessed towards the non-skin side in the thickness direction, and the density of the fibers constituting the absorbent core 121 in the compression section 123 is higher than that of the surrounding area. Therefore, after the excretory liquid flows down into the recessed compression section 123, it is easily introduced into the interior of the absorbent core 121 (towards the non-skin side in the thickness direction) by means of capillary action.

[0076] Furthermore, in the diaper 1 of this embodiment, when the "drainage test" was conducted, the drainage index was less than 50%. In the drainage test, after 40 ml of artificial urine was added to a predetermined position p0 on the surface sheet 20 four times, the drainage index related to the absorption rate and absorption volume of the artificial urine was calculated based on the measurement results of the predetermined position p0 by the moisture meter.

[0077] The reserved position p0 is as follows Figure 2 The diaper 1 in its unfolded and stretched state is positioned 50 mm off the ventral (front) side from the center line CL, which bisects the product in the length direction. Furthermore, the predetermined position p0 is the position on the center line bisects the absorbent core 121 in the width direction. In other words, the predetermined position p0 is the position where the wearer's urine outlet or its vicinity abuts. Therefore, the drainage test simulates the state of four 40 ml urine streams draining from the wearer's outlet towards the surface sheet 20.

[0078] A moisture meter measures the moisture content from the skin-side of the surface sheet 20, and the measurement result corresponds to the amount of artificial urine remaining on the surface sheet 20. A decrease in the moisture meter reading indicates a reduction in the amount of artificial urine on the surface sheet 20, meaning the artificial urine has been introduced into the interior of the diaper 1. Figure 9 As shown, immediately after adding artificial urine, the moisture meter reading rises sharply, then gradually decreases, indicating that the artificial urine has been introduced into the interior of the diaper 1. In other words, the lower moisture meter reading indicates that less artificial urine remains on the surface sheet 20, and the surface sheet 20 exhibits higher dryness.

[0079] The drainage index is as follows: Figure 10 A and Figure 10 B shows the ratio of the area A1 of the oblique section (change in water content) enclosed by the water meter measurement results when artificial urine was added for the fourth time to the area A0 of the quadrilateral (maximum water content).

[0080] Drainage index (%) =A1 / A0×100

[0081] In detail, during the period from the start of the 4th artificial urine drip (t4) to 5 minutes (300 seconds), the minimum value W0 (that is, the measurement value at time t4) and the maximum value W1 (that is, the measurement value immediately after the dripping ended) of the moisture meter are obtained. The value obtained by subtracting the minimum value W0 from the maximum value W1 is set as the maximum amount Wx (=W1-W0). The area A0 of the quadrilateral (maximum water content) is calculated as Wx × 300 (seconds). The area A1 of the sloping part (water content change) is the area enclosed by the minimum value W0 and the measurement results of the moisture meter during the period from the start of the 4th artificial urine drip (t4) to 5 minutes (the cumulative value of the measurement value relative to the minimum value W0).

[0082] Assuming that no artificial urine is introduced into the diaper 1 during the period from time t4 to 5 minutes later, and the moisture meter reading remains at the maximum moisture content Wx, then the area A1 remains essentially unchanged compared to the area A0, and the drainage index becomes close to 100%. On the other hand, if the amount of artificial urine on the surface plate 20 decreases and the moisture meter reading decreases, then the area A1 of the sloping portion decreases, and the drainage index also decreases. In other words, the drainage index represents the amount of artificial urine absorbed from the surface plate 20; the smaller the drainage index, the greater the absorption.

[0083] Furthermore, the slope of the moisture meter's measurement result (curve) indicates the rate at which artificial urine on surface plate 20 decreases, that is, the rate of absorption into the diaper 1. A steeper slope indicates a faster absorption rate. In the early stages of the period from time t4 until 5 minutes have elapsed, the moisture meter's measurement result decreases. In this case, the area A1 of the slope also decreases, and the drainage index also decreases. In other words, the drainage index represents the rate of absorption of artificial urine from surface plate 20; a smaller drainage index indicates a faster absorption rate.

[0084] Therefore, for the diaper 1 of this embodiment, which has an excretion index of 50% or less, the excretion is absorbed faster and in greater quantities compared to diapers with an excretion index of 50% or higher. Consequently, excretion is less likely to remain on the surface sheet 20, resulting in greater dryness on the surface sheet 20 (the side facing the skin). This is especially true when the wearer is an infant, as the amount of excretion per instance is relatively small (around 40 ml). Therefore, even with repeated excretions (up to four times), it is easy to ensure dryness on the surface sheet 20.

[0085] As described above, in the diaper 1 of this embodiment, the gaps g2 between the fibers f2 constituting the non-skin side 22 are small, making it easier for excrement to be introduced into the interior of the surface sheet 20. Furthermore, in the compression section 123, excrement is easily introduced into the interior of the absorbent core 121. Additionally, with an excretion index of 50% or less, the absorption rate of excrement from the surface sheet 20 is faster, and the absorption volume is greater.

[0086] Therefore, excrement is less likely to remain on the surface sheet 20, resulting in higher dryness on the surface sheet 20 (the skin side of the diaper 1). This reduces discomfort caused by a wet surface sheet, improving the comfort of wearing the diaper 1. Furthermore, liquid transfer from the non-skin side 22 with smaller gaps g2 to the skin side 21 with larger gaps g1 is less likely. Therefore, excrement absorbed by the absorbent body 12 is less likely to flow back (become damp) onto the surface sheet 12, maintaining dryness on the surface sheet 20.

[0087] A drainage test was conducted using diaper 1 (Example) of this embodiment and commercially available infant underwear-type diapers (Comparative Example). The results are shown below. Figure 9 as well as Figure 10 A, Figure 10 B. In the diaper 1 of the embodiment and the diaper of the comparative example, the structure of the surface sheet is different, and the absorbent core of the diaper of the comparative example is not provided with a compression part.

[0088] The test method for the "drainage test" is as follows. Figure 11 This is an explanatory diagram of the fixture 50 for setting diaper 1.

[0089] As the moisture meter, a fiber optic infrared moisture meter ("IM-3SRVMODEL-1000H (high moisture measurement type)" manufactured by Fujiwork Co., Ltd., or an equivalent moisture meter) was used. The artificial urine was prepared as follows: 200g of urea, 80g of sodium chloride, 8g of magnesium sulfate, 3g of calcium chloride, and approximately 1g of pigment: Blue No. 1 were dissolved in 10L of deionized water, and the surface tension was adjusted to 50mN / m to 55mN / m. Furthermore, the temperature of the artificial urine was maintained at approximately 37°C during the addition using a constant-temperature water bath.

[0090] (1) First, make a sample of the absorbent article that will be measured, such as Figure 2 As shown, the sample is positioned in an unfolded and extended state, with the skin side facing upwards. Determine the droplet placement point p0 (predetermined position) for the artificial urine in the sample. As already explained, the droplet placement point p0 (predetermined position) is the center position in the width direction, offset forward 50 mm from the center CL in the length direction of the product.

[0091] Furthermore, in the case of samples having a leak-proof wall portion 15, the leak-proof wall portion 15 can be partially removed. Additionally, the diaper 1 is not placed on a flat surface, but rather uses... Figure 11 The fixture 50 shown is mounted on a surface that curves gently downwards in a U-shape. The longitudinal length of the mounting surface of the fixture 50 is 450 mm, and the transverse length is 125 mm. The mounting surface is primarily inclined in the region extending inwards from both ends of the fixture 50 in the longitudinal direction, approximately one-third of the way in, with a height difference of 65 mm between the ends and the center in the longitudinal direction. The fixture 50 is positioned so that the center of the unfolded diaper 1 in the longitudinal direction is aligned with the center of the fixture 50 in the longitudinal direction.

[0092] (2) Next, the artificial urine dispensing section of the dispensing pump (Master FlexL / S Model No.7550-30 digital dispensing pump manufactured by Yamato Scientific Co., Ltd., or an equivalent dispensing pump) is fixed 10 mm above the sample. In order to dispense the artificial urine in four times, a laser thickness gauge (such as the IL series CMOS laser displacement sensor manufactured by Keyence Co., Ltd.) is used to measure the thickness of the sample at the dispensing position p0 during measurement, and the height of the dispensing pump is adjusted so that the distance between the dispensing section of the dispensing pump and the sample is constant (10 mm above).

[0093] (3) Then, 10 seconds after the measurement results from the moisture meter are obtained using the PC, the first drip begins. Artificial urine is dripped automatically using a delivery pump. The drip volume is set to 40 ml, and the drip rate is set to 480 ml / min.

[0094] (4) After that, five minutes have elapsed since the start of the previous addition, the next addition of artificial urine begins. Artificial urine is added four times at five-minute intervals. Then, the change in the moisture meter reading over time is obtained (curve).

[0095] (5) Perform the above measurements multiple times for each sample to obtain multiple moisture meter readings. Calculate the average of the multiple measurement results. Based on the average result (curve), such as... Figure 10 As shown, the drainage index is calculated.

[0096] exist Figure 9 The figure shows the average of four measurements taken with respect to diaper 1 of the embodiment (solid line curve) and the average of four measurements taken with respect to the diaper of the comparative example (dashed line curve). Additionally, the figure will... Figure 9 The measurement results after the fourth artificial urine droplet are shown in the figure. Figure 10 A, Figure 10 B.

[0097] according to Figure 9 The results show that after the first addition of artificial urine, in both the example and the comparative example, the moisture meter reading immediately decreased, the amount of liquid on the surface sheet 20 decreased, and the artificial urine had been introduced into the diaper. However, it is also known that as the number of second and third additions increased, in the comparative example, compared with the example, the rate of decrease in the moisture meter reading was slower, and the rate of absorption into the diaper decreased.

[0098] Then, based on the measurement results after the fourth addition, the drainage index of each diaper in the embodiment and the comparative example was calculated. The drainage index of the embodiment was 38%, and the drainage index of the comparative example was 68%. This is because, in the comparative example, compared with the embodiment, the dripping rate of artificial urine after the fourth addition was slower, and the moisture meter reading was also higher after 5 minutes, resulting in a larger amount of artificial urine remaining on the surface sheet. Thus, in diaper 1 of this embodiment, the drainage index is below 50%, and compared with the diaper of the comparative example, which has a drainage index above 50%, the absorption rate is faster and the absorption volume is larger after four additions of 40 ml of excrement. Therefore, in diaper 1 of this embodiment, the dryness of the surface sheet 20 is improved.

[0099] Furthermore, preferably, the longitudinal tensile strength of the skin side 21 of the surface sheet 20 is higher than that of the non-skin side 22. Therefore, the skin side 21 is less prone to flattening in the thickness direction, while the non-skin side 22 is more prone to flattening in the thickness direction.

[0100] Therefore, as Figure 6 A, Figure 6As shown in B, when the wearer applies body pressure while wearing diaper 1, the thickness of the non-skin side 22 tends to decrease (ta > tb) compared to before wearing. Therefore, in the non-skin side 22, in addition to the finer fiber diameter, the gaps g2 between the fibers are further reduced by flattening. Consequently, capillary action is more likely to occur, and excretory fluid on the surface sheet 20 easily transfers from the skin side 21 to the non-skin side 22, improving the dryness of the surface sheet 20.

[0101] On the other hand, the flattening of the skin side 21 is less when body pressure is applied, and it is easier to maintain the thickness when wearing it. Therefore, the excrement absorbed by the absorbent body 12 is less likely to flow back onto the surface sheet 20, and it is easier to maintain the dryness of the surface sheet 20.

[0102] Furthermore, the comparison of the breaking strength of the skin side 21 and the non-skin side 22 can be performed using known methods. For example, it can be determined based on the degree of fiber damage when the surface is rubbed. First, a sample of a predetermined size (e.g., 300 mm in length × 100 mm in width) is cut from the surface sheet 20 of the object. Two samples are prepared, one for the skin side 21 and one for the non-skin side 22. The samples are fixed on the measuring stage of a dyeing fastness-to-rub tester (e.g., a tester manufactured by Daiei Scientific Instruments Co., Ltd. or equivalent). When measuring the skin side 21, the skin side of the surface sheet 20 is facing upwards, and when measuring the non-skin side 22, the non-skin side of the surface sheet 20 is facing upwards. Next, a 300 g weight is mounted on the upper surface of the rubbing terminal of the dyeing fastness-to-rub tester, and a cloth strip forming a rubbing surface is attached to the lower surface of the rubbing terminal. Next, the surface of the sample fixed on the stage is rubbed using the rubbing surface in the rubbing terminal. At this point, rubbing is performed along a predetermined length (e.g., 100 mm) in a direction corresponding to the length of the diaper 1, with the number of reciprocations of the rubbing terminal set to 50. Then, the fuzzing state of the sample surface after rubbing with the rubbing terminal is observed. If the fuzzing on the skin side is greater than that on the non-skin side, it can be confirmed that the breaking strength of the skin side 21 is higher than that of the non-skin side 22.

[0103] Alternatively, comparisons can be made based on the rate of strength reduction. Three types of samples are prepared: samples before the rubbing fastness test, samples after the rubbing fastness test on the skin side, and samples after the rubbing fastness test on the non-skin side. Each sample, 50 mm wide, is placed in a tensile testing machine (chuck distance 50 mm) and stretched at 100 mm / min to measure the maximum strength. The strength of the sample before the rubbing fastness test is set to 100%, and the strengths of the samples after the rubbing fastness test on either the skin side or the non-skin side are compared. The rate of strength reduction is calculated as: (strength of the sample after rubbing fastness test ÷ strength of the sample before rubbing fastness test) × 100. If the rate of strength reduction for the sample rubbed on the skin side is greater than that for the sample rubbed on the non-skin side, it can be confirmed that the breaking strength of the skin side 21 is higher than that of the non-skin side 22.

[0104] In addition, it is preferable that the total length of the fibers constituting the non-skin side 22 of the surface sheet 20 is longer than the total length of the fibers constituting the skin side 21.

[0105] By increasing the total length of the fibers constituting the non-skin side 22, the gaps g2 between more fibers f2 become narrower when body pressure is applied. Therefore, the absorption of excretory fluid from the skin side 21 to the non-skin side 22 is improved, and the dryness of the surface sheet 20 is enhanced. Furthermore, if the total fiber length of the non-skin side 22 is longer and the amount of fibers in the non-skin side 22 is greater, the thickness of the non-skin side 22 can be prevented from becoming too thin when body pressure is applied. Therefore, the volume of the non-skin side 21, which is the area where capillary action occurs, can be ensured to maintain the absorption of excretory fluid during wear.

[0106] Furthermore, the total length of the fibers constituting the skin side 21 and the non-skin side 22 can be confirmed using known methods. For example, the surface sheet 20 can be cut at multiple points along its width in the length direction. Next, the cut surfaces are magnified and photographed using an optical microscope (e.g., a Keyence VHX-7000 digital microscope or an equivalent microscope). In the multiple cross-sectional images, regions containing thicker fibers, regions containing thinner fibers, and regions containing a mixture of fibers of varying thicknesses are identified. The center position in the thickness direction of the region containing the mixture of fibers of varying thicknesses is determined, and the portion closer to the skin side than this center position is designated as the skin side 21, and the portion closer to the non-skin side than this center position is designated as the non-skin side 22. Additionally, if, in the multiple cross-sectional images, the number of cross-sections of fibers in the non-skin side 22 is greater than the number of cross-sections of fibers in the skin side 21, it can be confirmed that the total length of the fibers constituting the non-skin side 22 is longer.

[0107] In addition, such as Figure 4 As shown, the diaper 1 has a core sheet 122 on the skin side as a sheet material adjacent to the surface sheet 20 on the non-skin side in the thickness direction. Preferably, the hydrophilicity of the skin side of the core sheet 122 is higher than that of the skin side of the surface sheet 20.

[0108] Therefore, the excretory liquid can easily transfer from the surface sheet 20 to the sheet with higher hydrophilicity (in this case, the core sheet 122). Thus, the excretory liquid transfers sequentially from the surface sheet 20 to the sheet with higher hydrophilicity, and is less likely to remain on the surface sheet 20. This improves the drying properties of the surface sheet 20. However, it is not limited to the above; alternatively, the hydrophilicity of the skin-like side of the core sheet 122 may be lower than that of the skin-like side of the surface sheet 20.

[0109] The hydrophilicity (hydrophilicity) of a sheet refers to the ease with which a liquid can spread on the surface of the sheet and the fact that the surface of the sheet has a contact angle of less than 90°. The contact angle is the angle between the tangent of the profile curve of the water droplet and the horizontal plane at the intersection of the profile curve of the water droplet and the horizontal plane when water is dropped onto the surface of the sheet (horizontal plane).

[0110] The hydrophilicity can be measured using known methods. For example, the surface sheet 20 and the core sheet 122 of the object are removed from diaper 1. Droplets of ion-exchanged water are attached to the skin-side of each sheet, and the droplets are recorded. The contact angle is measured based on the recorded images. More specifically, a Keyence VHX-1000 microscope or an equivalent microscope is used as the measuring device, with a medium-magnification zoom lens mounted at a 90° tilt. The sheet is placed on the measuring stage of the measuring device with the skin-side facing upwards, and a droplet of 3 μL of ion-exchanged water is attached to it. The image of the droplet is recorded and imported into the measuring device. From the multiple recorded images, 10 images with clear droplet tips are selected, and the contact angle of the droplet is measured for each of the 10 images. The average of these contact angles is taken as the contact angle of each sheet. The measurement environment is set to 20°C / 50%RH.

[0111] In addition, such as Figure 5 As shown in Figure A, the surface sheet 20 of this embodiment is shaped with concave and convex features, with both the skin-side and non-skin-side surfaces having concave and convex shapes. Multiple protrusions 23 extending towards the skin side of the surface sheet 20 are arranged in the width direction. Recesses 24 extending in the length direction are formed between the protrusions 23. A second recess 25, further recessed towards the non-skin side than the recess 24, is formed within the recess 24. (The text repeats itself here.) Figure 5As shown in Figure B, the second recess 25 is formed in the recess 24 at predetermined intervals along the length direction. Such a surface sheet 20 can be formed, for example, by passing the surface sheet 20 between a pair of heating pattern rollers having a relief pattern corresponding to the relief pattern of the surface sheet 20 formed on their outer peripheral surfaces.

[0112] By making the skin-friendly side of the surface sheet 20 concave-convex in this way, the contact area between the wearer and the surface sheet 20 can be reduced. In the diaper 1 of this embodiment, the dryness of the surface sheet 20 is improved, wherein, by reducing the contact area between the wearer and the surface sheet 20, the wearer is less likely to feel moisture in the diaper 1. In addition, since it is less likely to apply body pressure to the surface sheet 20 as a whole, the excrement absorbed by the absorbent core 121 is less likely to flow back onto the surface sheet 20. Furthermore, the formation of a channel for moist air in the recess 24 also improves the breathability of the diaper 1. Therefore, the wearing comfort of the diaper 1 is improved.

[0113] Furthermore, when the protrusion 23 is flattened due to pressure from the wearer's body, the second recess 25 is less likely to come into contact with the wearer's skin. Therefore, by having the surface sheet 20 have the second recess 25, the contact area between the wearer and the surface sheet 20 can be reduced more reliably.

[0114] Furthermore, the excreted fluid that is discharged onto the surface sheet 20 is diffused along the length direction via the recess 24 while being introduced into the interior of the surface sheet 20. Therefore, the diaper 1 can be used effectively in the planar direction.

[0115] Furthermore, a through hole 26 is provided on the side of the second recess 25. Such a through hole 26 can be formed, for example, by utilizing the height difference between the protrusion 23 and the second recess 25 during the embossing of the surface sheet 20. Preferably, the surface sheet 20 has a through hole 26 extending along the thickness direction of the surface sheet 20. As a result, excrement discharged onto the surface sheet 20 can easily transfer from the through hole 26 into the interior of the diaper 1 (absorbent body 12). Therefore, excrement is less likely to remain on the surface sheet 20, and the dryness of the surface sheet 20 is improved.

[0116] However, the structure of the surface sheet 20 is not limited to the structure described above. Figure 12 A and Figure 12 B is an explanatory diagram of a modified example of surface sheet 20. For example, it can also be as follows: Figure 12 As shown in Figure A, the skin-side surface (skin-side 21) of the surface sheet 20 has an uneven shape, while the non-skin-side surface (non-skin-side 22) is flat. Alternatively, it can be as follows... Figure 12 As shown in Figure B, the surface plate 20 is not formed into a bumpy shape, but rather a flat shape. Additionally, Figure 5 The through hole 26 of A extends along the width of the diaper 1 through the wall portion surrounding the second recess 25. However, it can also be as follows:Figure 12 As shown in Figure B, the surface sheet 20 is provided with a through hole 26 that extends through the surface sheet 20 along the thickness direction of the diaper 1.

[0117] Furthermore, preferably, the absorbent core 121 is provided with a compression portion 123, wherein, for example... Figure 7 A, Figure 7 As shown in Figure B, the compression section 123 extends in a linear shape. Furthermore, the linearly extending compression section 123 can be either a compression section formed by arranging multiple point-like compression sections in a line, or a groove-shaped compression section formed by continuous compression. In this case, the excrement easily diffuses along the compression section 123, and the excrement expands along the planar direction of the absorbent core 121. Therefore, the excrement transferred from the surface sheet 20 to the absorbent core 121 is introduced into the interior of the absorbent core 121 while diffusing along the compression section 123. In this way, the excrement is sequentially transferred inside the diaper 1, thereby reducing the likelihood of excrement residue on the surface sheet 20 and improving the dryness of the surface sheet 20. Additionally, the absorbent core 121 can be effectively utilized in the planar direction, increasing the amount of excrement that can be absorbed by the absorbent core 121. Therefore, it is easier to maintain the dryness of the surface sheet 20 even with multiple or large amounts of excretion.

[0118] However, it is not limited to the above. Alternatively, multiple point-like compression sections 123 may be discretely arranged in the absorbent core 121. In this case, it is also easier to introduce the excreted liquid into the interior of the absorbent core 121, where the compression sections 123 have been densely packed. Furthermore, in Figure 7 In A, multiple linear compression sections 123, which meander along the width direction and extend along the length direction, are arranged in the width direction. Figure 7 In B, multiple hexagonal linear compression portions 123 are arranged in both the length and width directions. However, the shape, arrangement, and number of the compression portions 123 shown are just one example and are not particularly limited. For example, although in Figure 7 In A, the compression portion 123 is arranged in the entire planar area of ​​the absorbent core 121, but the compression portion 123 may also be arranged in a local area of ​​the planar area of ​​the absorbent core 121.

[0119] In addition, such as Figure 8 As shown in Figure A, in the compression portion 123 formed in the absorbent core 121 in this embodiment, the absorbent core 121 and the core packing sheet 122 on the skin side are compressed from the skin side, but the surface sheet 20 is not compressed.

[0120] In this case, the surface sheet 20 and the skin-side core sheet 122 are not tightly attached, easily forming a gap between them. Excrement can easily be temporarily stored in this gap, and the excrement absorbed by the absorbent core 121 is less likely to flow back onto the surface sheet 20. Therefore, it is easier to maintain the dryness of the surface sheet 20. Furthermore, by not forming a denser and harder compression portion 123 on the surface sheet 20, the skin-touch feel of the surface sheet 20 becomes soft. Therefore, the wearing comfort of the diaper 1 is improved.

[0121] Furthermore, as described above, on the skin-side surface of the surface sheet 20, a plurality of protrusions 23 extending along the length direction are arranged at intervals in the width direction. Therefore, the contact area between the surface sheet 20 and the wearer can be reduced, or the excretory fluid can be diffused along the length direction.

[0122] In addition, there are situations where the user (caregiver, etc.) of diaper 1 touches the surface sheet 20 of the used diaper 1 along its length to check the dryness of the surface sheet 20. At this time, because the surface sheet 20 has irregularities extending along its length and no compression portion 123 is formed there, the finger can move smoothly. Therefore, the user can easily recognize that this is a product with high dryness of the surface sheet 20. Especially in the case of diapers for infants and young children, since caregivers, etc., do not actually wear them, they can confirm that the dryness is high, and thus feel at ease letting the child wear the diaper 1.

[0123] However, it is not limited to the above content, and can also include, for example Figure 8 As shown in Figure B, the surface sheet 20 and the absorbent core 121 are compressed together in the compression section 123. In this case, the excreted liquid discharged onto the surface sheet 20 easily flows down into the compression section 123, and then the excreted liquid is easily introduced into the interior of the absorbent core 121 by utilizing the capillary effect of the high-density compression section 123. Therefore, the dryness of the surface sheet 20 is improved. In addition, by compressing the surface sheet 20, the visual visibility of the compression section 123 is improved. Therefore, the user can easily recognize that this is a product in which the excreted liquid is easily absorbed.

[0124] Alternatively, in the compression section 123, the core sheet 122 may not be compressed, but only the absorbent core 121 may be compressed. Furthermore, although in Figure 8 In A, local compression was performed on the thickness direction of the absorbent core 121, but compression could also be performed on the entire thickness direction of the absorbent core 121.

[0125] Furthermore, preferably, the skin-side portion 21 of the surface sheet 20 has a high unit area weight region 21H with a higher fiber unit area weight and a low unit area weight region 21L with a lower fiber unit area weight than the high unit area weight region 21H. This allows for an increase in the fiber density of the high unit area weight region 21H or an increase in its thickness. On the other hand, it allows excretory fluid to flow rapidly into the interior of the low unit area weight region 21L, where the gaps between the fibers are larger.

[0126] For example, in the surface sheet 20 of this embodiment, such as Figure 5 As shown in Figure A, the high weight-per-unit area region 21H of the skin side 21 is located in the convex portion 23, and the low weight-per-unit area region 21L of the skin side 21 is located in the concave portion 24. When the thicknesses of the high weight-per-unit area region 21H and the low weight-per-unit area region 21L are the same, the fiber density of the high weight-per-unit area region 21H is higher than that of the surrounding area. Therefore, the excretory fluid can be introduced from the high weight-per-unit area region 21H into the interior of the surface sheet 20 using capillary action, and the excretory fluid is less likely to remain in the surface sheet 20.

[0127] Furthermore, when the densities of the high unit area weight region 21H and the low unit area weight region 21L are the same, such as Figure 12 As shown in Figure A, the thickness of the high weight-per-unit area region 21H can be increased. Therefore, an uneven shape can be formed on the skin side 21, reducing the contact area between the surface sheet 20 and the wearer.

[0128] In addition, preferably, such as Figure 5 A, Figure 12 As shown in Figure A, the high weight-per-unit area region 21H protrudes towards the skin side compared to the low weight-per-unit area region 21L. This creates a textured surface on the skin side of the surface sheet 20. Consequently, the contact area between the surface sheet 20 and the wearer is reduced, making it less likely for the wearer to feel moisture in the diaper 1. Furthermore, because it is less likely to apply body pressure to the surface sheet 20 as a whole, excrement absorbed by the absorbent core 121 is less likely to flow back onto the surface sheet 20.

[0129] Furthermore, the presence of a high weight-per-unit-area region 21H and a low weight-per-unit-area region 21L on the skin side 21 can be confirmed using known methods. For example, it can be confirmed by magnifying a cross-section obtained by cutting the surface sheet 20 along the width direction using an optical microscope or similar device.

[0130] Furthermore, it is preferable that the amount of reabsorption is less than 1.0g when the reabsorption test is conducted. The test measures the amount of reabsorption of artificial urine that returns to the surface sheet 20 after four 40ml drops of artificial urine have been added to the surface sheet 20. Therefore, compared to cases where the reabsorption is greater than 1.0g, it is easier to maintain the dryness of the surface sheet 20. Consequently, the wearing comfort of the diaper 1 is improved.

[0131] The amount of moisture reversion can be measured using the following test methods.

[0132] First, fix the sample (diaper 1) in its unfolded and stretched state with the skin side facing upwards. In the case of a sample with a leak-proof wall section 15, a portion of the leak-proof wall section 15 may be removed to allow for the placement of filter paper. Additionally, measure the weight w0 (g) of approximately 50g of filter paper (e.g., Toyo Filter Paper, ADVANTEC Qualitative Filter Paper No. 2).

[0133] Next, determine the location where the artificial urine is added to the sample. The addition location is the center of the width direction, offset forward 70 mm from the center of the sample's length direction.

[0134] Next, position the dropping device (burette or delivery pump (e.g., the device used in the draining test, or an equivalent device)) 10 mm above the sample dropping position. Also, align the center of the hollow cylinder (60 mm inner diameter, 55 g) with the sample dropping position and place the hollow cylinder on top of the sample.

[0135] Next, add 40 ml of artificial urine four times at 10-minute intervals. The drip rate was set to 40 ml / 5 seconds. The artificial urine was the same as that described in the excretion test.

[0136] Then, 5 minutes after the fourth artificial urine drop was added, the filter paper, with its center aligned with the sample drop position, was placed on top of the sample, and a weight (10cm × 10cm, 3.5kg) was placed on it. The weight was removed 3 minutes after the weight was placed, and the weight w1 (g) of the filter paper was measured.

[0137] Calculate the value obtained by subtracting the weight of the filter paper before the test from the weight of the filter paper before the test, w1, and set this value as the rewetting amount (=w1-w0).

[0138] A moisture reabsorption test was conducted on diaper 1 of the embodiment and diaper 1 of the comparative embodiment, which underwent a drainage test. The results showed that the moisture reabsorption amount of the comparative embodiment diaper was 2.5g, while that of diaper 1 of the embodiment was 0.5g. Therefore, it can be seen that, compared to the comparative embodiment diaper, diaper 1 of the embodiment, with a moisture reabsorption amount of 1.0g or less, is more likely to maintain the dryness of the surface sheet 20.

[0139] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the invention. It is self-evident that the present invention can be modified and improved without departing from its spirit, and that equivalents are included in the present invention.

[0140] Explanation of reference numerals in the attached figures

[0141] 1. Underwear-type disposable diaper (absorbent); 2. Side joint; 10. Absorbent body; 12. Absorbent core; 121. Absorbent core; 122. Core packing sheet; 123. Compression part; 13. Backing sheet; 15. Leak-proof wall part; 16. Leak-proof wall elastic member; 17. Leg opening elastic member; 20. Surface sheet; 21. Skin side; 21H. High weight per unit area area; 21L. Low weight per unit area area; 22. Non-skin side; 23. Protrusion; 24. Concave; 25. Second concave; 26. Through hole; 30. Front waist section; 31. Skin side sheet; 32. Non-skin side sheet; 33. Waist elastic member; 34. Cover sheet; 40. Rear waist section; 41. Skin side sheet; 42. Non-skin side sheet; 43. Waist elastic member; 44. Cover sheet; 50. Fixture.

Claims

1. An absorbent article having mutually orthogonal length, width and thickness directions in an unfolded state, and having an absorbent core and a surface sheet, characterized in that, the surface sheet has a skin side portion on the skin side in the thickness direction and a non-skin side portion at a position on the non-skin side in the thickness direction further from the skin side portion, the average fiber diameter of the fibers constituting the non-skin side portion is smaller than the average fiber diameter of the fibers constituting the skin side portion, the absorbent core has a compressed portion compressed from the skin side in the thickness direction, when a discharge test is performed, the discharge index is 50% or less, in the discharge test, after 40 ml of artificial urine is added four times to a predetermined position on the surface sheet, the discharge index relating to the absorption speed and absorption amount of the artificial urine is calculated based on the measurement results of the predetermined position by a moisture meter.

2. The absorbent article according to claim 1, characterized in that, the breaking strength in the length direction of the skin side portion of the surface sheet is higher than the breaking strength in the length direction of the non-skin side portion.

3. The absorbent article according to claim 1 or 2, characterized in that, the total length of the fibers constituting the non-skin side portion of the surface sheet is longer than the total length of the fibers constituting the skin side portion.

4. The absorbent article according to claim 1 or 2, characterized in that, the absorbent article has a sheet material adjacent to the surface sheet on the non-skin side in the thickness direction, the hydrophilicity of the skin side surface of the sheet material is higher than the hydrophilicity of the skin side surface of the surface sheet.

5. The absorbent article according to claim 1 or 2, characterized in that, in the compressed portion, the surface sheet is not compressed.

6. The absorbent article according to claim 5, characterized in that, on the skin side surface of the surface sheet, a plurality of convex portions extending in the length direction are arranged at intervals in the width direction.

7. The absorbent article according to claim 1 or 2, characterized in that, in the compressed portion, the surface sheet and the absorbent core are compressed together.

8. The absorbent article according to claim 1 or 2, characterized in that, the surface sheet has a through hole extending through the thickness direction of the surface sheet.

9. The absorbent article according to claim 1 or 2, characterized in that, the skin side portion of the surface sheet has a high basis weight area in which the basis weight of the fibers is high, and a low basis weight area in which the basis weight of the fibers is lower than in the high basis weight area.

10. The absorbent article according to claim 9, characterized in that, the high basis weight area protrudes toward the skin side more than the low basis weight area.

11. The absorbent article according to claim 1 or 2, characterized in that, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ When the test for measuring the rewet amount is performed, the rewet amount is 1.0 g or less, and the test for measuring the rewet amount is a test for measuring the rewet amount of the artificial urine returned to the surface sheet in a case where 40 ml of the artificial urine is dripped four times onto the surface sheet.

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