Absorbent article

Abstract

An absorbent article characterized in that: a top sheet (20) has a skin-side part (21) and a non-skin-side part (22); fibers constituting the non-skin-side part (22) have a smaller average fineness than fibers constituting the skin-side part (21); an absorbent core (121) has a compressed part (123) compressed from the skin side in the thickness direction; and, when a liquid drainage test is performed in which, after 40 ml of artificial urine is dripped four times at a prescribed position on the top sheet (20), a liquid drainage index relating to the speed and amount of absorption of artificial urine is obtained on the basis of the measurement result at the prescribed position from a moisture meter, the liquid drainage index is not more than 50%.

Description

absorbent articles

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

[0002] The absorbent body of the disposable diaper in Patent Document 1 has non-stacking portions extending in the vertical direction. Therefore, the non-stacking portions become deformation starting points, allowing the absorbent body to fit the wearer's body. Furthermore, by providing a topsheet within the non-stacking portions, the formation of spaces between the topsheet and the absorbent body is prevented, allowing liquid excreted in the non-stacking portions to smoothly migrate downward in the thickness direction.

[0003] JP 2016-30109 A

[0004] However, in Patent Document 1, in order to allow the topsheet to exist (be pushed into) the non-stacking portion, the fineness of the fibers in the lower layer of the topsheet is made higher than that of the upper layer, making the bonding points between the fibers sparser and making the lower layer easier to stretch. In this case, the gaps between the fibers in the lower layer of the topsheet are larger than those in the upper layer. As a result, capillary action from the upper layer to the lower layer of the topsheet does not work, and the topsheet is not able to draw excreted liquid into its interior. As a result, liquid tends to remain on the topsheet, and the topsheet does not maintain a sufficient dryness.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide an absorbent article in which the dryness of the topsheet (skin side) is improved.

[0006] The main invention for achieving the above object is an absorbent article having, in an unfolded state, longitudinal, width, and thickness directions that are orthogonal to one another, an absorbent core, and a topsheet, wherein the topsheet 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 of the skin-side portion, the average fineness of the fibers constituting the non-skin-side portion is smaller than the average fineness of the fibers constituting the skin-side portion, and the absorbent core has a compressed portion compressed from the skin side in the thickness direction, and when a drainage test is conducted in which 40 ml of artificial urine is dropped four times at a predetermined position on the topsheet and a drainage index related to the absorption rate and amount of the artificial urine is determined based on the measurement results of the predetermined position using a moisture meter, the drainage index is 50% or less. Other features of the present invention will be made clear by the description in this specification and the accompanying drawings.

[0007] According to the present invention, it is possible to provide an absorbent article in which the dryness of the topsheet (skin side) is improved.

[0008] 1 is a schematic perspective view of the diaper 1; 2 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as viewed from the skin side; 3 is a schematic cross-sectional view taken along line A-A in FIG. 2; 4 is a schematic cross-sectional view taken along center line CL in FIG. 2; 5A is a schematic cross-sectional view of the topsheet 20, and FIG. 5B is a plan view of the topsheet 20, as viewed from the skin side; 6A is an explanatory diagram of the fibers constituting the topsheet 20, and FIG. 6B is an explanatory diagram of the topsheet 20 when worn; 7A and FIG. 7B are plan views of the absorbent body 12, as viewed from the skin side; 8A and FIG. 8B are explanatory diagrams of the compression section 123; 9 are diagrams showing the results of a drainage test; 10A and FIG. 10B are diagrams showing the results of a drainage test; 11 are explanatory diagrams of a jig 50 for setting the diaper 1; 12A and FIG. 12B are explanatory diagrams showing modified topsheets 20.

[0009] The present specification and the accompanying drawings make clear at least the following: (Aspect 1) An absorbent article having, in an unfolded state, a longitudinal direction, a width direction, and a thickness direction that are orthogonal to one another, and comprising an absorbent core and a topsheet, wherein the topsheet 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 of the skin-side portion in the thickness direction, the average fineness of the fibers constituting the non-skin-side portion is smaller than the average fineness of the fibers constituting the skin-side portion, the absorbent core has a compressed portion compressed from the skin side in the thickness direction, and when 40 ml of artificial urine is dropped four times at predetermined positions on the topsheet and then a drainage index related to the absorption rate and amount of the artificial urine is determined based on the measurement results of the predetermined positions using a moisture meter, the absorbent article has a drainage index of 50% or less.

[0010] According to Aspect 1, the interfiber gaps are smaller in the non-skin-side portion than in the skin-side portion, making it easier for excreted liquid to migrate from the skin-side portion to the non-skin-side portion. Furthermore, excreted liquid that migrates to the skin-side portion of the absorbent core is more easily drawn into the absorbent core by the compressed portion with high fiber density. This reduces the likelihood of excreted liquid remaining on the topsheet, improving the dryness of the topsheet. Furthermore, compared to when the drainage index is higher than 50%, the topsheet absorbs excreted liquid more quickly and absorbs more, improving the dryness of the topsheet.

[0011] (Aspect 2) The absorbent article according to Aspect 1, wherein the skin side portion of the topsheet has a higher breaking strength in the longitudinal direction than the non-skin side portion.

[0012] According to Aspect 2, the non-skin-side portion is easily crushed when the wearer's body pressure is applied, and the gaps between the fibers in the non-skin-side portion become smaller. This makes it easier for excrement to migrate from the skin-side portion to the non-skin-side portion. On the other hand, the skin-side portion is less likely to be crushed and its thickness (bulk) is maintained, making it difficult for excrement absorbed by the absorbent core to flow back onto the topsheet, improving and maintaining the dryness of the topsheet.

[0013] (Aspect 3) The absorbent article according to Aspect 1 or Aspect 2, characterized in that the total length of the fibers constituting the non-skin side portion of the topsheet is longer than the total length of the fibers constituting the skin side portion of the topsheet.

[0014] According to Aspect 3, when the wearer's body pressure is applied, the inter-fiber gaps of more fibers narrow, facilitating the transfer of excrement from the skin-side portion to the non-skin-side portion, thereby improving the dryness of the topsheet.

[0015] (Aspect 4) An absorbent article according to any one of Aspects 1 to 3, further comprising a sheet adjacent to the non-skin side of the top sheet in the thickness direction, wherein the hydrophilicity of the skin side of the sheet is higher than the hydrophilicity of the skin side of the top sheet.

[0016] According to Aspect 4, excreted liquid that has migrated from the skin-side portion of the topsheet to the non-skin-side portion is more likely to migrate to the highly hydrophilic sheet, which allows the excreted liquid to gradually migrate into the absorbent article, making it less likely for the excreted liquid to remain on the topsheet, and improving the dryness of the topsheet.

[0017] (Aspect 5) The absorbent article according to any one of Aspects 1 to 4, wherein the compressed portion does not compress the topsheet.

[0018] According to Aspect 5, voids are easily formed between the topsheet and the absorbent core. The excrement absorbed by the absorbent core is easily stored in the voids and is less likely to flow back onto the topsheet. This helps maintain the dryness of the topsheet.

[0019] (Aspect 6) The absorbent article according to Aspect 5, wherein a plurality of protrusions extending in the longitudinal direction are arranged at intervals in the width direction on the skin side of the topsheet.

[0020] According to Aspect 6, the contact area between the topsheet and the wearer can be reduced, making it difficult for the wearer to feel the wetness of the absorbent article, improving comfort. In addition, when the user touches the topsheet to check the dryness of the topsheet, the user's fingertips can move smoothly in the longitudinal direction, making it easier for the user to recognize that the product has a high level of dryness on the topsheet.

[0021] (Aspect 7) The absorbent article according to any one of Aspects 1 to 4, wherein the compression section compresses the topsheet together with the absorbent core.

[0022] According to Aspect 7, excrement that flows into the densified compressed sections is more likely to be drawn from the topsheet to the absorbent core by capillary action. In addition, the increased visibility of the compressed sections makes it easier for users to recognize that the product is one that easily absorbs excrement.

[0023] (Aspect 8) The absorbent article according to any one of Aspects 1 to 7, wherein the topsheet has through holes that penetrate the topsheet in the thickness direction.

[0024] According to Aspect 8, excrement falls into the interior of the absorbent article through the through-holes in the topsheet, increasing the rate at which excrement is absorbed by the topsheet and improving the dryness of the topsheet.

[0025] (Aspect 9) An absorbent article according to any one of Aspects 1 to 8, characterized in that the skin side portion of the topsheet has a high basis weight region in which the fiber has a high basis weight, and a low basis weight region in which the fiber has a lower basis weight than the high basis weight region.

[0026] According to Aspect 9, the high basis weight region can increase the thickness or density of a portion of the skin-side portion. Increasing the thickness (bulk) of the high basis weight region can suppress backflow of excreted liquid. In addition, increasing the density of the high basis weight region makes it easier for excreted liquid on the topsheet to be drawn into the interior by capillary action.

[0027] (Aspect 10) The absorbent article according to aspect 9, wherein the high basis weight region protrudes closer to the skin than the low basis weight region.

[0028] According to Aspect 10, it is possible to form irregularities on the skin side of the topsheet, thereby reducing the contact area between the topsheet and the wearer. This makes it difficult for the wearer to feel the dampness of the absorbent article, improving comfort.

[0029] (Aspect 11) An absorbent article according to any one of Aspects 1 to 10, characterized in that, when a test is conducted to measure the amount of rewet of the artificial urine returning to the top sheet when 40 ml of artificial urine is dropped onto the top sheet four times, the rewet amount is 1.0 g or less.

[0030] According to aspect 11, compared to when the rewet amount is greater than 1.0 g, the excrement absorbed by the absorbent core can be prevented from returning to the topsheet, and the dryness of the topsheet can be maintained.

[0031] Embodiments The absorbent article according to the present invention will be described using a pants-type disposable diaper 1 for infants (hereinafter also referred to as "diaper 1") as an example. However, the absorbent article according to the present invention also includes tape-type disposable diapers, shorts-type napkins, absorbent pads, sanitary napkins, and other absorbent articles. Furthermore, the wearer of the absorbent article is not limited to infants, but may also be an adult, an animal, or other living being.

[0032] <Configuration of diaper 1> Fig. 1 is a schematic perspective view of the diaper 1. Fig. 2 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as viewed from the skin side. Fig. 3 is a schematic cross-sectional view taken along line A-A in Fig. 2. Fig. 4 is a schematic cross-sectional view taken along center line CL in Fig. 2.

[0033] The "stretched state" of the diaper 1 refers to a state in which the entire diaper 1 is stretched without wrinkles, specifically, a state in which the dimensions of each component constituting the diaper 1 (e.g., the absorbent body 10 and waist-lined sections 30, 40, etc., described below) are stretched to the extent that they match or are close to the dimensions of the individual components. The "unfolded state" of the diaper 1 refers to a state in which the pair of side joining sections 2 provided on both sides of the diaper 1 are separated, and the diaper 1 is opened and unfolded flat.

[0034] The diaper 1 has a vertical direction, a width direction, and a front-to-rear direction that are perpendicular to each other, and has a waist opening BH and a pair of leg openings LH. The upper side in the vertical direction corresponds to the waist opening BH side, and the lower side corresponds to the crotch side. The front side in the front-to-rear direction corresponds to the wearer's abdomen side, and the rear side corresponds to the wearer's back side. The width direction is a direction along the stretch direction of the elastic threads 33, 43 of the front waist portion 30 and the rear waist portion 40. The vertical direction is a direction perpendicular to the stretch direction.

[0035] The diaper 1 is a so-called three-piece pants-type diaper having a liquid-absorbent main body 10 and a pair of waist-surrounding sections 30, 40. Of the pair of waist-surrounding sections, the one covering the wearer's abdominal region is also referred to as the front waist-surrounding section 30, and the other covering the wearer's dorsal region is also referred to as the rear waist-surrounding section 40.

[0036] In the unfolded state shown in Fig. 2, the diaper 1 has a longitudinal direction, a width direction, and a thickness direction, which are perpendicular to one another. The longitudinal direction is along the longitudinal direction of the absorbent main body 10 and along the vertical direction of the pants-type diaper 1. The thickness direction, as shown in Fig. 3, is the direction in which the materials constituting the diaper 1 are layered. In the thickness direction, the side that contacts the wearer's skin is referred to as the skin side, and the opposite side is referred to as the non-skin side. In the unfolded state, the front waistband 30 and the rear waistband 40 are aligned parallel to each other with a gap in the longitudinal direction, with the absorbent main body 10 spanning between them, with each longitudinal end of the absorbent main body 10 bonded and fixed to the skin side of the nearest waistband 30, 40, resulting in a generally H-shaped appearance in a plan view. From this state, the diaper 1 is folded in half along the longitudinal center line CL. In this folded state, the opposing front waistline portion 30 and rear waistline portion 40 are joined and connected at both widthwise sides to form a pair of side joint portions 2. The side joint portions 2 are formed by known joining means such as welding or adhesive.

[0037] The absorbent body 10 has an absorbent body 12, a liquid-permeable top sheet 20 arranged closer to the skin than the absorbent body 12, and a back sheet 13 arranged closer to the skin than the absorbent body 12. The back sheet 13 has a two-layer structure consisting of a liquid-impermeable sheet 13a and a hydrophobic outer sheet 13b arranged on the far side of the liquid-impermeable sheet 13a. However, the absorbent body 10 may also include other sheet members. For example, a second sheet (not shown) may be provided between the top sheet 20 and the absorbent body 12 in the thickness direction.

[0038] The absorbent body 12 has an absorbent core 121 and a core wrap sheet 122 that covers the outer peripheral surface of the absorbent core 121. The absorbent core 121 is a member that absorbs and retains excreted liquids such as urine, and is formed from liquid-absorbent fibers such as pulp fibers mixed with superabsorbent polymer (SAP). Examples of the core wrap sheet 122 include liquid-permeable sheet members such as tissue paper and nonwoven fabric.

[0039] A pair of leakage preventing walls 15 is provided along the longitudinal direction of the absorbent main body 10 on both widthwise sides of the absorbent main body 10. In Figure 4, a part of the exterior sheet 13b extends outward from both ends of the absorber 20 in the widthwise direction and is folded toward the skin at multiple locations to form the pair of leakage preventing walls 15. A leakage preventing wall elastic member 16 such as rubber thread is attached to the tip of the leakage preventing wall 15 in a state stretched along the longitudinal direction of the absorbent main body 10, so that the leakage preventing wall 15 can stand up toward the skin. In addition, leg elastic members 17 such as rubber thread are attached to both widthwise sides of the absorbent main body 10 in a state stretched along the longitudinal direction of the absorbent main body 10.

[0040] The front waistline portion 30 and the back waistline portion 40 each have a skin-side sheet 31, 41, a non-skin-side sheet 32, 42, and a plurality of waistline elastic members 33, 43 such as rubber threads. The plurality of waistline elastic members 33, 43 are arranged side by side in the vertical direction between the skin-side sheet 31, 41 and the non-skin-side sheet 32, 42, and are attached in a stretched state in the width direction. The stretchability of the waistline elastic members 33, 43 allows the front waistline portion 30 and the back waistline portion 40 to fit the waist of the wearer.

[0041] Furthermore, cover sheets 34, 44 may be provided so as to cover the upper end of the absorbent main body 10 from the skin side. The cover sheets 34, 44 can prevent the absorbent main body 10 from opening. Furthermore, print sheets 35, 45 on which a pattern or the like is printed may be provided between the skin side sheets 31, 41 and the non-skin side sheets 32, 32.

[0042] 3, the front waistline portion 30 and the rear waistline portion 40 have different planar shapes in the unfolded and stretched state. The front waistline portion 30 has a vertical length that is roughly the same as that of the side joint portion 2 and a rectangular shape that is long in the width direction. The rear waistline portion 40 has a rectangular portion that overlaps with the front waistline portion 30 and a generally trapezoidal portion 40E that extends downward from the rectangular portion 30. The extending portion 40E can cover the wearer's buttocks.

[0043] The basic configuration of the diaper 1 has been described above, but the above configuration is merely an example and is not intended to be limiting. For example, the front waistline portion 30 and the rear waistline portion 40 may be formed from a single continuous member, or an outer member may be provided in the crotch area connecting the front waistline portion 30 and the rear waistline portion 40. Furthermore, the elastic members such as the waistline elastic members 33, 43 may be sheet-like elastic members instead of rubber threads.

[0044] Dryness on the Topsheet 20 = Fig. 5A is a schematic cross-sectional view of the topsheet 20, and Fig. 5B is a plan view of the topsheet 20 (part) as seen from the skin side. Fig. 6A is an explanatory diagram of the fibers that make up the topsheet 20, and Fig. 6B is an explanatory diagram of the topsheet 20 when worn. Figs. 7A and 7B are plan views of the absorbent body 12 as seen from the skin side. Figs. 8A and 8B are explanatory diagrams of the compressed portion 123. Figs. 9, 10A, and 10B show the results of a drainage test.

[0045] As shown in Fig. 6A, the topsheet 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 of the skin-side portion 21. Note that, although the topsheet 20 of this embodiment is a sheet with a concave-convex shape as shown in Fig. 5A, for ease of understanding in the drawings, the topsheet 20 is illustrated flat in Figs. 6A and 6B.

[0046] As shown in Figure 6A, the average fineness of the fibers f2 constituting the non-skin-side portion 22 of the topsheet 20 is smaller than the average fineness of the fibers f1 constituting the skin-side portion 21. In other words, the fibers f2 constituting the non-skin-side portion 22 are thinner than the fibers f1 constituting the skin-side portion 21. Therefore, in the skin-side portion 21, it is difficult for additional fibers f1 to penetrate between the fibers f1, and the fibers f1 are sparsely distributed. In contrast, in the non-skin-side portion 22, additional fibers f2 are easily penetrated between the fibers f2, and the fibers f2 are densely distributed. Therefore, the gaps g2 between the fibers f2 constituting the non-skin-side portion 22 are smaller than the gaps g1 between the fibers f1 constituting the skin-side portion 21. Therefore, excreted liquids, such as urine, exuded on the topsheet 20 penetrate into the skin-side portion 21 and then easily migrate to the non-skin-side portion 22 due to capillary action. In other words, excreted liquids are easily drawn into the topsheet 20.

[0047] The average fineness of fibers f1 and f2 can be compared using a known method. For example, after freezing the target topsheet 20 with liquid nitrogen or the like, fibers of a predetermined length (e.g., 5 mm) are cut out from ten arbitrary locations on each of the skin-side portion 21 and the non-skin-side portion 22. That is, fibers are cut out from the skin-facing side of the topsheet 20, and fibers are also cut out from the non-skin-facing side of the topsheet 20. The ends of the cut fibers are cut perpendicular to the direction of fiber extension. The cut surfaces are photographed at a predetermined magnification, and the fiber diameters (mm) of the fibers are measured from the resulting cross-sectional photograph. The average fiber diameter of the ten fibers taken from the skin-side portion 21 (skin-facing side) is calculated, and the average fiber diameter of the ten fibers taken from the non-skin-side portion 22 (non-skin-facing side) is also calculated. If the average fiber diameter of the non-skin side portion 22 is smaller than the average fiber diameter of the skin side portion 21, it can be confirmed that the average fineness of the fibers f2 constituting the non-skin side portion 22 is smaller than the average fineness of the fibers f1 constituting the skin side portion 21.

[0048] Furthermore, the portion of the topsheet 20 composed of fibers f1 with a thick average fiber diameter is referred to as the skin-side portion 21, and the portion composed of fibers f2 with a thin average fiber diameter is referred to as the non-skin-side portion 22. The thicknesses of the skin-side portion 21 and the non-skin-side portion 22 may be the same or different. Furthermore, thick fibers f1 and thin fibers f2 are mixed at the boundary between the skin-side portion 21 and the non-skin-side portion 22. Therefore, the center position in the thickness direction of the region where fibers of different thicknesses are mixed is taken as the boundary, and the portion closer to the skin than this boundary is referred to as the skin-side portion 21, and the portion closer to the non-skin than this boundary is referred to as the non-skin-side portion 22.

[0049] Furthermore, it is preferable that the fibers f1, f2 constituting the skin side portion 21 and the non-skin side portion 22, respectively, contain thermoplastic fibers. In this case, in the manufacturing process of the topsheet 20, heat is applied to the laminated fibers (fiber web), causing some of the fibers to heat-fuse together and form the topsheet into a sheet shape.

[0050] 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 polypentylene terephthalate, polyamide polymers such as nylon 6 and nylon 6,6, acrylic polymers, polyacrylonitrile polymers, or modified products thereof, or combinations thereof.

[0051] 7 and 8, the absorbent core 121 has compressed portions 123 that are compressed from the skin side in the thickness direction. The compressed portions 123 are not compressed across the entire plane of the absorbent core 121 (so-called flat pressing), but are portions where the absorbent core 121 is partially compressed. Note that the topsheet 20 in Fig. 8 is also shown flat, rather than having an uneven shape, for ease of understanding.

[0052] In the compressed portions 123, the absorbent core 121 is recessed toward the non-skin side in the thickness direction, and the density of the fibers constituting the absorbent core 121 is higher than in the surrounding area. Therefore, after the excreted liquid falls into the recessed compressed portions 123, it is easily drawn into the absorbent core 121 (toward the non-skin side in the thickness direction) by capillary action.

[0053] Furthermore, in the diaper 1 of this embodiment, when 40 ml of artificial urine is dropped four times onto a predetermined position p0 on the top sheet 20, and then a ``drainage test'' is performed to determine a drainage index related to the absorption rate and absorption amount of artificial urine based on the measurement results of the predetermined position p0 using a moisture meter, the drainage index is 50% or less.

[0054] The predetermined position p0 is a position 50 mm toward the ventral side (front side) of the center line CL that bisects the diaper 1 in the longitudinal direction when the diaper 1 is in an unfolded and stretched state as shown in Figure 2. It is also a position on the center line that bisects the absorbent core 121 in the width direction. In other words, the predetermined position p0 is a position that abuts the wearer's urinary excretion opening or its vicinity. Therefore, the drainage test is a test that simulates a state in which 40 ml of urine is excreted from the wearer's excretion opening toward the topsheet 20 four times.

[0055] The moisture meter measures the amount of moisture from the skin-facing side of the topsheet 20, and the measurement result corresponds to the amount of artificial urine remaining on the topsheet 20. A decrease in the moisture meter measurement result indicates that the amount of artificial urine on the topsheet 20 has decreased and that the artificial urine has been absorbed into the diaper 1. As shown in Figure 9, the moisture meter measurement value rises sharply immediately after the artificial urine is dripped, and then gradually decreases, indicating that the artificial urine has been absorbed into the diaper 1. In other words, a small moisture meter measurement result indicates that a small amount of artificial urine remains on the topsheet 20 and that the topsheet 20 is highly dry.

[0056] 10A and 10B, the drainage index is the ratio of the area A1 of the shaded area (change in moisture content) surrounded by the moisture meter measurement results to the area A0 of the rectangle (maximum moisture content) in the moisture meter measurement results after the fourth drop of artificial urine. Drainage index (%) = A1 / A0 × 100

[0057] Specifically, the minimum value W0 (i.e., the measurement at time t4) and the maximum value W1 (i.e., the measurement immediately after the end of dripping) of the moisture meter measurement values ​​are obtained during the five minutes (300 seconds) from the start of the fourth drip of artificial urine (t4). The maximum amount Wx (= W1 - W0) is determined by subtracting the minimum value W0 from the maximum value W1. The area A0 of the rectangle (maximum moisture amount) is calculated as Wx × 300 (seconds). The area A1 of the shaded area (moisture amount change) is the area enclosed by the minimum value W0 of the moisture meter measurement values ​​and the moisture meter measurement results during the five minutes from the start of the fourth drip of artificial urine (t4) (the integrated value of the measurements relative to the minimum value W0).

[0058] If the artificial urine is not absorbed into the diaper 1 during the five minutes from time t4 and the moisture meter measurement result remains at the maximum moisture content Wx, the area A1 will remain almost the same as the area A0, and the drainage index will be close to 100%. On the other hand, if the amount of artificial urine on the topsheet 20 decreases and the moisture meter measurement result decreases, the area A1 of the shaded area will decrease and the drainage index will also decrease. In other words, the drainage index represents the amount of artificial urine absorbed from the topsheet 20, and it can be seen that the smaller the drainage index, the greater the amount absorbed.

[0059] The slope of the moisture meter measurement results (graph) represents the rate at which the artificial urine on the topsheet 20 decreases, i.e., the rate at which the artificial urine is absorbed into the diaper 1. The steeper the slope, the faster the absorption rate, and the moisture meter measurement results decrease early in the five minutes from time t4. In this case, the area A1 of the shaded area also decreases, and the drainage index also decreases. In other words, the drainage index represents the rate at which the artificial urine is absorbed from the topsheet 20, and it can be seen that the smaller the drainage index, the faster the absorption rate.

[0060] Therefore, the diaper 1 of this embodiment, which has a drainage index of 50% or less, absorbs excreted liquid faster and in larger amounts than diapers with a drainage index higher than 50%. This reduces the likelihood of excreted liquid remaining on the topsheet 20, ensuring a high level of dryness on the topsheet 20 (skin side). In particular, when the wearer is an infant, the amount of excreted liquid per excretion is small (around 40 ml). Therefore, even if the wearer excretes repeatedly (even four times), the topsheet 20 remains dry.

[0061] As described above, in the diaper 1 of this embodiment, the gaps g2 between the fibers f2 constituting the non-skin side portion 22 are small, and excreted liquid is easily drawn into the topsheet 20. Furthermore, in the compressed portions 123, excreted liquid is easily drawn into the absorbent core 121. Furthermore, the drainage index is 50% or less, and the excreted liquid is quickly absorbed from the topsheet 20 and absorbed in large quantities.

[0062] Therefore, excreted liquid is less likely to remain on the topsheet 20, and the topsheet 20 (the skin side of the diaper 1) remains dry. This prevents the wearer from feeling uncomfortable due to a wet topsheet, improving the comfort of wearing the diaper 1. Furthermore, liquid is less likely to migrate from the non-skin side portion 22, which has a smaller gap g2, to the skin side portion 21, which has a larger gap g1. This makes it less likely that excreted liquid absorbed by the absorber 12 will return (rewet) onto the topsheet 12, and the topsheet 20 remains dry.

[0063] A drainage test was conducted using a diaper 1 (Example) of the present embodiment and a conventional pants-type diaper for infants (Comparative Example). The results are shown in Figures 9, 10A, and 10B. The diaper 1 of the Example and the diaper of the Comparative Example have different topsheet configurations, and the diaper of the Comparative Example does not have compressed portions in its absorbent core.

[0064] The test method for the "liquid drainage test" is as follows. Figure 11 is an explanatory diagram of a jig 50 on which the diaper 1 is placed. The moisture meter used was a fiber-type infrared moisture meter ("IM-3SRV MODEL-1000H (high moisture measurement type)" manufactured by Fujiwork Co., Ltd., or an equivalent device. The artificial urine was prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride, and approximately 1 g of dye, Blue No. 1, in 10 L of ion-exchanged water, so that the surface tension was 50 to 55 mN / m. A water bath was used to ensure that the temperature of the artificial urine was approximately 37°C when it was dropped.

[0065] (1) First, a sample of the absorbent article to be measured is placed in an unfolded and stretched state with the skin side facing up, as shown in Figure 2. The artificial urine drip position p0 (predetermined position) on the sample is identified. As mentioned above, the drip position p0 (predetermined position) is the center position in the width direction, 50 mm forward of the center CL in the longitudinal direction of the product.

[0066] In the case of a sample having a leak-barrier wall 15 or the like, a portion of the leak-barrier wall 15 may be cut out. The diaper 1 is placed not on a flat surface, but on a gently downwardly curved U-shaped surface using a jig 50 shown in FIG. 11 . The vertical length of the placement surface of the jig 50 is 450 mm, and the horizontal length is 125 mm. The placement surface is mainly inclined in a region extending approximately one-third inward from both vertical ends of the jig 50, with a height difference of 65 mm between the vertical ends and the center. The diaper 1 in its unfolded state is placed with its longitudinal center aligned with the vertical center of the jig 50.

[0067] (2) Next, the artificial urine dispensing portion of the liquid delivery pump (Digital Liquid Delivery Pump Master Flex L / S Model No. 7550-30 manufactured by Yamato Scientific Co., Ltd., or an equivalent) is fixed at a position 10 mm above the sample. Since the artificial urine is dispensed in four separate dispenses, the thickness of the sample at the dispensing position p0 during measurement is determined using a laser thickness meter (for example, a CMOS Laser AppliSensor IL series manufactured by Keyence Corporation), and the height of the liquid delivery pump is adjusted so that the dispensing portion of the liquid delivery pump is at a constant position (10 mm above) the sample.

[0068] (3) Then, 10 seconds after the PC starts acquiring the moisture meter measurement results, the first drip begins. The artificial urine is automatically dripped using the liquid pump. The amount of each drip is 40 ml, and the drip rate is 480 ml / min.

[0069] (4) After that, the next drip of artificial urine begins 5 minutes after the start of the previous drip. The artificial urine is dripped four times at 5-minute intervals. Then, the change in the moisture meter measurement results over time (graph) is obtained.

[0070] (5) The above measurement is performed multiple times for each sample, and multiple measurement results are obtained using the moisture meter. The average value of the multiple measurement results is calculated. The drainage index is calculated from the average result (graph) as shown in Figure 10.

[0071] Fig. 9 shows the average value of four measurements for Example Diaper 1 (solid line graph) and the average value of four measurements for Comparative Example Diaper (dotted line graph). Furthermore, Fig. 10A and Fig. 10B show the measurement results after the fourth drop of artificial urine.

[0072] 9, it can be seen that after the first drop of artificial urine, the moisture meter reading immediately decreased in both the Example and Comparative Example, the amount of liquid on the topsheet 20 decreased, and the artificial urine was absorbed into the diaper. However, as the number of drops increased to the second and third times, the rate at which the moisture meter reading decreased in the Comparative Example was slower than in the Example, indicating that the rate at which the artificial urine was absorbed into the diaper was decreasing.

[0073] Based on the measurement results after the fourth drop, the drainage index of each diaper of the Example and Comparative Example was calculated. The drainage index of the Example was 38%, and the drainage index of the Comparative Example was 68%. This is because the Comparative Example had a slower drip rate of artificial urine after the fourth drop, and the moisture meter reading was still high even after 5 minutes had elapsed, resulting in a larger amount of artificial urine remaining on the topsheet. Thus, the diaper 1 of this embodiment had a drainage index of 50% or less, and thus had a faster absorption rate and a larger absorption amount after 40 ml of excrement was dropped four times compared to the Comparative Example diaper with a drainage index higher than 50%. Therefore, the diaper 1 of this embodiment exhibited improved dryness on the topsheet 20.

[0074] It is also preferable that the skin side portion 21 of the topsheet 20 has a higher longitudinal breaking strength than the non-skin side portion 22. This makes the skin side portion 21 less likely to be crushed in the thickness direction, while the non-skin side portion 22 is more likely to be crushed in the thickness direction.

[0075] 6A and 6B, when the wearer's body pressure is applied while wearing the diaper 1, the thickness of the non-skin-side portion 22 tends to decrease (ta > tb) compared to the thickness before wearing. In this case, the non-skin-side portion 22 has a small fiber diameter, and the fibers are crushed, further reducing the interfiber gaps g2. This facilitates capillary action, facilitating the transfer of excrement on the topsheet 20 from the skin-side portion 21 to the non-skin-side portion 22, improving the dryness of the topsheet 20.

[0076] On the other hand, the skin-side portion 21 is less likely to collapse when body pressure is applied, and the thickness is likely to be maintained even when worn. Therefore, excrement absorbed by the absorbent body 12 is less likely to flow back onto the topsheet 20, and the topsheet 20 is likely to remain dry.

[0077] The breaking strength of the skin-side portion 21 and the non-skin-side portion 22 can be compared using known methods. For example, this can be confirmed by the degree of fiber breakdown when the surface is rubbed. First, a sample of a predetermined size (e.g., 300 mm long x 100 mm wide) is cut from the target topsheet 20. Two samples are prepared, one for the skin-side portion 21 and one for the non-skin-side portion 22. The samples are fixed on the measurement stage of a dyed fabric friction fastness tester (e.g., manufactured by Daiei Scientific Instruments Co., Ltd. or equivalent). When measuring the skin-side portion 21, the topsheet 20 is fixed on the stage with the skin-side side facing up, and when measuring the non-skin-side portion 22, the topsheet 20 is fixed on the stage with the non-skin-side side facing up. Next, a 300 g weight is attached to the top surface of the friction terminal of the dyed fabric friction fastness tester, and a cloth tape forming a friction surface is attached to the bottom surface. Next, the surface of the sample fixed on the stage is rubbed against the friction surface of the friction terminal. At this time, a predetermined length (e.g., 100 mm) is rubbed in the direction corresponding to the longitudinal direction of the diaper 1, and the friction terminal is moved back and forth 50 times. Then, the state of fuzz on the sample surface after rubbing with the friction terminal is observed. If the fuzz on the skin-side surface is greater than that on the non-skin-side surface, it can be confirmed that the skin-side portion 21 has a higher breaking strength than the non-skin-side portion 22.

[0078] Alternatively, comparison may be made based on the strength reduction rate. A total of three samples are prepared: a sample before the friction fastness test, a sample after the friction fastness test on the skin-facing side, and a sample after the friction fastness test on the non-skin-facing side. Each 50 mm wide sample is placed in a tensile tester (chuck distance: 50 mm) and pulled at a speed of 100 mm / min to measure the maximum strength. The strength of each sample after the friction fastness test on the skin-facing side or non-skin-facing side is compared, with the strength of the sample before the friction fastness test being taken as 100%. The strength reduction rate is calculated according to the formula: sample strength after friction fastness ÷ sample strength before friction fastness × 100. If the strength reduction rate of the sample rubbed on the skin-facing side is greater than the strength reduction rate of the sample rubbed on the non-skin-facing side, it can be confirmed that the skin-side portion 21 has a higher breaking strength than the non-skin-side portion 22.

[0079] It is also preferable that the total length of the fibers constituting the non-skin side portion 22 of the topsheet 20 be longer than the total length of the fibers constituting the skin side portion 21.

[0080] Because the total length of the fibers constituting the non-skin side portion 22 is long, the gaps g2 between the more fibers f2 become narrower when the wearer's body pressure is applied. This increases the ability to draw excrement from the skin side portion 21 to the non-skin side portion 22, improving the dryness of the topsheet 20. Furthermore, if the total fiber length of the non-skin side portion 22 is long and the fiber content of the non-skin side portion 22 is large, the thickness of the non-skin side portion 22 can be prevented from becoming too thin even when body pressure is applied. This ensures the bulk of the non-skin side portion 21, which is the region where capillary action works, and maintains the ability to draw excrement when worn.

[0081] The comparison of the total length of the fibers constituting the skin-side portion 21 and the non-skin-side portion 22 can be confirmed by a known method. For example, the topsheet 20 is cut widthwise at multiple arbitrary positions along the longitudinal direction. Next, an optical microscope (e.g., a Keyence VHX-7000 digital microscope or equivalent) is used to magnify and photograph the cut surfaces. In each of the photographed cross-sectional images, regions containing thick fibers, regions containing thin fibers, and regions containing a mixture of fibers of different thicknesses are identified. The center position in the thickness direction of the region containing a mixture of fibers of different thicknesses is identified, and the region closer to the skin than that center position is designated as the skin-side portion 21, and the region closer to the non-skin than that center position is designated as the non-skin-side portion 22. If the number of fiber cross sections is greater in the non-skin-side portion 22 than in the skin-side portion 21 in the multiple cross-sectional images, it can be confirmed that the total length of the fibers constituting the non-skin-side portion 22 is longer.

[0082] As shown in Figure 4, the diaper 1 also has a skin-side core wrap sheet 122 adjacent to the non-skin side in the thickness direction of the topsheet 20. The hydrophilicity of the skin-side surface of this core wrap sheet 122 is preferably higher than the hydrophilicity of the skin-side surface of the topsheet 20.

[0083] By doing so, excreted liquid is more likely to migrate from the topsheet 20 to the sheet with higher hydrophilicity (here, the core wrap sheet 122). Therefore, excreted liquid migrates sequentially from the topsheet 20 to the sheet with higher hydrophilicity, making it less likely for excreted liquid to remain on the topsheet 20. This improves the dryness of the topsheet 20. However, this is not limited to the above, and the hydrophilicity of the skin-side surface of the core wrap sheet 122 may be lower than the hydrophilicity of the skin-side surface of the topsheet 20.

[0084] The hydrophilicity of a sheet means that a liquid spreads easily on the surface of the sheet and that the surface of the sheet has a contact angle of 90° or less. The contact angle is the angle between the horizontal plane and the tangent to the contour curve of the water (droplet) at the intersection of the contour curve and the horizontal plane when water is dropped on the surface (horizontal plane) of the sheet.

[0085] The hydrophilicity can be measured by a known method. For example, the target topsheet 20 and sheet (core wrap sheet 122) are removed from the diaper 1. A droplet of ion-exchanged water is applied to the skin-side surface of each sheet, the droplet is recorded, and the contact angle is measured based on the recorded image. More specifically, a microscope VHX-1000 manufactured by Keyence Corporation or an equivalent device is used as the measuring device, with a medium-magnification zoom lens attached at a 90° angle. The sheet is placed on the measuring stage of the measuring device so that the skin-side surface faces upward, a 3 μL droplet of ion-exchanged water is applied, and the image of the droplet is recorded and imported into the measuring device. From the multiple recorded images, 10 images with clear droplet edges are selected, and the contact angle of the droplet is measured for each of the 10 images. The average of these contact angles is used as the contact angle of each sheet. The measurement environment is 20°C / 50% RH.

[0086] As shown in Figure 5A, the topsheet 20 of this embodiment is embossed with a concave-convex shape, with both the skin-side and non-skin-side surfaces having a concave-convex shape. On the skin-side surface of the topsheet 20, convex portions 23 protruding toward the skin extend in the longitudinal direction, with multiple convex portions 23 arranged in the width direction. Concave portions 24 extending in the longitudinal direction are formed between the convex portions 23. Second concave portions 25 recessed further toward the non-skin side than the concave portions 24 are formed in the concave portions 24. As shown in Figure 5B, the second concave portions 25 are formed at predetermined intervals in the longitudinal direction in the concave portions 24. Such a topsheet 20 can be formed, for example, by passing the topsheet 20 between a pair of heated pattern rollers having concaves and convexes formed on the outer circumferential surfaces corresponding to the concave-convex pattern of the topsheet 20.

[0087] By forming an uneven shape on the skin side of the topsheet 20 in this way, the contact area between the wearer and the topsheet 20 can be reduced. In the diaper 1 of this embodiment, the dryness of the topsheet 20 is improved, but by reducing the contact area between the wearer and the topsheet 20, the wearer is even less likely to feel wetness in the diaper 1. In addition, since body pressure is less likely to be applied to the entire topsheet 20, excrement absorbed by the absorbent core 121 is less likely to flow back onto the topsheet 20. Furthermore, the recesses 24 form paths for moist air to pass through, improving the breathability of the diaper 1. This improves the comfort of wearing the diaper 1.

[0088] Furthermore, even if the wearer's body pressure is applied and the protrusions 23 are crushed, the second recesses 25 are unlikely to come into contact with the wearer's skin. Therefore, by providing the topsheet 20 with the second recesses 25, the contact area between the wearer and the topsheet 20 can be more reliably reduced.

[0089] Furthermore, excreted liquid excreted on the topsheet 20 is dispersed in the longitudinal direction by the recesses 24 and drawn into the interior of the topsheet 20. This allows the diaper 1 to be effectively utilized in the planar direction.

[0090] Furthermore, through-holes 26 are provided on the side surfaces of the second recesses 25. Such through-holes 26 can be formed, for example, by creating a height difference between the protrusions 23 and the second recesses 25 when the topsheet 20 is shaped into a concave-convex shape. In this manner, the topsheet 20 preferably has through-holes 26 that penetrate in the thickness direction of the topsheet 20. This allows excreted liquid excreted on the topsheet 20 to easily migrate through the through-holes 26 into the interior of the diaper 1 (the absorbent body 12). This makes it difficult for excreted liquid to remain on the topsheet 20, improving the dryness of the topsheet 20.

[0091] However, the configuration of the topsheet 20 is not limited to the above. Figures 12A and 12B are explanatory diagrams of modified topsheets 20. For example, as shown in Figure 12A, the skin-side surface (skin-side portion 21) of the topsheet 20 may be uneven, while the non-skin-side surface (non-skin-side portion 22) may be flat. Alternatively, as shown in Figure 12B, the topsheet 20 may be flat without being uneven. Furthermore, the through-holes 26 in Figure 5A penetrate the wall surrounding the second recess 25 in the width direction of the diaper 1. However, as shown in Figure 12B, the topsheet 20 may have through-holes 26 penetrating the wall surrounding the second recess 25 in the thickness direction of the diaper 1.

[0092] The absorbent core 121 is provided with compressed portions 123, which preferably extend linearly as shown in Figures 7A and 7B. The compressed portions 123 may be a linear arrangement of multiple dot-like compressed portions, or may be continuously compressed grooves. In this case, excreted liquid is more likely to spread along the compressed portions 123 and spread in the planar direction of the absorbent core 121. Therefore, excreted liquid that migrates from the topsheet 20 to the absorbent core 121 is drawn into the absorbent core 121 while spreading along the compressed portions 123. This gradual migration of excreted liquid within the diaper 1 reduces the likelihood of excreted liquid remaining on the topsheet 20, improving the dryness of the topsheet 20. Furthermore, the absorbent core 121 can be effectively utilized in the planar direction, increasing the amount of excreted liquid that can be absorbed by the absorbent core 121. Therefore, even if multiple excretions are made or a large amount of excreted liquid is excreted, the topsheet 20 tends to maintain a dry state.

[0093] However, the absorbent core 121 may have a plurality of discretely arranged point-like compressed portions 123. In this case, too, excrement is more easily drawn into the absorbent core 121, which has been densified by the compressed portions 123. Also, in FIG. 7A , a plurality of linear compressed portions 123 extending longitudinally while meandering in the width direction are arranged in the width direction. In FIG. 7B , a plurality of hexagonal linear compressed portions 123 are arranged in the longitudinal and width directions. However, the shape, arrangement, number, etc. of the illustrated compressed portions 123 are merely examples and are not particularly limited. For example, while the compressed portions 123 are arranged over the entire plane of the absorbent core 121 in FIG. 7A , the compressed portions 123 may be arranged over only a portion of the plane of the absorbent core 121.

[0094] In addition, the compression portion 123 formed on the absorbent core 121 of this embodiment compresses the core wrap sheet 122 on the skin side and the absorbent core 121 from the skin side, as shown in Figure 8A, but does not compress the top sheet 20.

[0095] In this case, the topsheet 20 and the skin-side core wrap sheet 122 are not in close contact with each other, and gaps are likely to form between them. Excrement is likely to be temporarily stored in these gaps, making it difficult for the excrement absorbed by the absorbent core 121 to flow back onto the topsheet 20. This helps to maintain the dryness of the topsheet 20. Furthermore, since the topsheet 20 does not have high-density, relatively hard compressed portions 123, the topsheet 20 feels soft against the skin. This improves the comfort of wearing the diaper 1.

[0096] Furthermore, as described above, a plurality of longitudinally extending protrusions 23 are arranged at intervals in the width direction on the skin side of the topsheet 20. This reduces the contact area between the topsheet 20 and the wearer and helps to diffuse excrement in the longitudinal direction.

[0097] In addition, a user (parent, etc.) of the diaper 1 may touch the topsheet 20 of the diaper 1 along the longitudinal direction with their hand after use to check the dryness of the topsheet 20. In this case, the topsheet 20 has longitudinally extending irregularities and no compressed portions 123, which allows the user's fingers to move smoothly. This makes it easier for the user to recognize that the topsheet 20 is a product with a high level of dryness. In particular, in the case of a diaper 1 for infants, parents, etc. do not actually wear the diaper, so being able to confirm the high level of dryness allows them to have their child wear it with peace of mind.

[0098] However, without being limited to the above, as shown in Figure 8B, the compressed sections 123 may compress the topsheet 20 together with the absorbent core 121. In this case, excreted liquid excreted on the topsheet 20 tends to fall into the compressed sections 123, and then, due to capillary action in the densified compressed sections 123, the excreted liquid tends to be drawn into the absorbent core 121. This improves the dryness of the topsheet 20. Furthermore, because the topsheet 20 is compressed, the visibility of the compressed sections 123 is improved. This makes it easier for the user to recognize that the product is one that easily absorbs excreted liquid.

[0099] Alternatively, the compression section 123 may compress only the absorbent core 121 without compressing the core wrap sheet 122. In addition, although Fig. 8A and other figures show that a portion of the absorbent core 121 is compressed in the thickness direction, the entire absorbent core 121 in the thickness direction may be compressed.

[0100] Furthermore, the skin side portion 21 of the topsheet 20 preferably has a high basis weight region 21H, where the fiber basis weight is high, and a low basis weight region 21L, where the fiber basis weight is lower than that of the high basis weight region 21H. This allows the fiber density of the high basis weight region 21H to be increased and the thickness of the high basis weight region 21H to be increased. On the other hand, excreted liquid can be quickly absorbed into the low basis weight region 21L, where the voids between the fibers are larger.

[0101] For example, in the topsheet 20 of this embodiment, as shown in Fig. 5A, the high basis weight regions 21H of the skin-side portion 21 are located in the convex portions 23, and the low basis weight regions 21L of the skin-side portion 21 are located in the concave portions 24. When the high basis weight regions 21H and the low basis weight regions 21L have the same thickness, the fiber density of the high basis weight regions 21H is higher than that of the surrounding areas. Therefore, excreted liquid can be drawn into the topsheet 20 from the high basis weight regions 21H by capillary action, making it less likely for excreted liquid to remain on the topsheet 20.

[0102] Furthermore, when the density of the high basis weight region 21H and the density of the low basis weight region 21L are the same, the thickness of the high basis weight region 21H can be increased as shown in Fig. 12A. This allows the skin side of the skin side portion 21 to have an uneven shape, thereby reducing the contact area with the wearer.

[0103] 5A and 12A, the high basis weight region 21H preferably protrudes closer to the skin side than the low basis weight region 21L. This allows the surface area of ​​the topsheet 20 to be uneven on the skin side. This reduces the contact area between the topsheet 20 and the wearer, making the wearer less likely to feel wetness in the diaper 1. Furthermore, since body pressure is less likely to be applied to the entire topsheet 20, excrement absorbed by the absorbent core 121 is less likely to flow back onto the topsheet 20.

[0104] The presence of the high basis weight region 21H and the low basis weight region 21L in the skin side portion 21 can be confirmed by a known method, for example, by observing a cross section of the topsheet 20 cut in the width direction under magnification using an optical microscope or the like.

[0105] Furthermore, when a test is conducted to measure the amount of rewet of artificial urine returning to the topsheet 20 when 40 ml of artificial urine is dropped onto the topsheet 20 four times, it is preferable that the rewet amount is 1.0 g or less. This makes it easier to maintain the dryness of the topsheet 20 compared to when the rewet amount is greater than 1.0 g, thereby improving the comfort of the diaper 1.

[0106] The rewet amount can be measured by the following test method. First, a sample (diaper 1) in an unfolded and stretched state is fixed with the skin side facing up. In the case of a sample having a leakage-preventing wall 15 or the like, a portion of the leakage-preventing wall 15 may be cut out so that a filter paper can be placed thereon. The weight w0 (g) of approximately 50 g of filter paper (e.g., Advantec Qualitative Filter Paper No. 2, manufactured by Toyo Roshi Co., Ltd.) is also measured. Next, the position where the artificial urine is dropped on the sample is identified. The dropping position is the center of the width direction of the sample, 70 mm forward of the center of the longitudinal direction. Next, set the dropping device (burette or liquid delivery pump (e.g., the same as that used in the drainage test or equivalent) so that its dropping part is 10 mm above the sample dropping position. Also, place a hollow cylinder (inner diameter 60 mm, 55 g) on ​​the sample, aligning its center with the sample dropping position. Next, 40 ml of artificial urine is dropped four times at 10-minute intervals. The dropping rate is 40 ml / 5 seconds. The artificial urine is the same as that described in the drainage test. Then, 5 minutes after the start of the fourth drop of artificial urine, place the filter paper, whose weight has been measured, on the sample, aligning its center with the sample dropping position, and place a weight (flat size 10 cm × 10 cm, 3.5 kg) on ​​top of it. 3 minutes after placing the weight, remove the weight and measure the weight w1 (g) of the filter paper. The weight of the filter paper before the test, w0, is subtracted from the weight of the filter paper after the test, w1, to calculate the rewet amount (= w1 - w0).

[0107] A rewet test was conducted on the Example diaper 1 and the Comparative Example diaper that had undergone the drainage test. The results showed that the Comparative Example diaper had a rewet amount of 2.5 g, while the Example (present embodiment) diaper 1 had a rewet amount of 0.5 g. Therefore, it was found that the diaper 1 of the present embodiment, which has a rewet amount of 1.0 g or less, is more likely to maintain dryness on the topsheet 20 than the Comparative Example diaper.

[0108] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

[0109] DESCRIPTION OF SYMBOLS 1 Pants-type disposable diaper (absorbent article), 2 Side joint portion, 10 Absorbent main body, 12 Absorbent body, 121 Absorbent core, 122 Core wrap sheet, 123 Compressed portion, 13 Back sheet, 15 Leakage preventing wall portion, 16 Leakage preventing wall elastic member, 17 Leg-hole elastic member, 20 Top sheet, 21 Skin-side portion, 21H High basis weight region, 21L Low basis weight region, 22 Non-skin-side portion, 23 Convex portion, 24 Concave portion, 25 Second concave portion, 26 Through-hole, 30 Front waist portion, 31 Skin-side sheet, 32 Non-skin-side sheet, 33 Waist-hole elastic member, 34 Cover sheet, 40 Rear waist portion, 41 Skin-side sheet, 42 Non-skin-side sheet, 43 Waist-hole elastic member, 44 Cover sheet, 50 Jigs,

Claims

1. An absorbent article having, in an unfolded state, longitudinal, width and thickness directions which are perpendicular to one another, an absorbent core and a top sheet, wherein the top 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 of the skin side in the thickness direction, the average fineness of the fibers constituting the non-skin side portion is smaller than the average fineness of the fibers constituting the skin side portion, and the absorbent core has a compressed portion compressed from the skin side in the thickness direction, and wherein, when 40 ml of artificial urine is dropped four times at a specified position on the top sheet and then a drainage test is conducted to determine a drainage index related to the absorption speed and absorption amount of the artificial urine based on the measurement results of the specified position with a moisture meter, the drainage index is 50% or less.

2. An absorbent article according to claim 1, characterized in that the skin side portion of the top sheet has a higher breaking strength in the longitudinal direction than the non-skin side portion.

3. An absorbent article as described in claim 1 or 2, characterized in that the total length of the fibers constituting the non-skin side portion of the top sheet is longer than the total length of the fibers constituting the skin side portion of the top sheet.

4. An absorbent article as described in claim 1 or 2, comprising a sheet adjacent to the non-skin side of the top sheet in the thickness direction, and the hydrophilicity of the skin side of the sheet is higher than the hydrophilicity of the skin side of the top sheet.

5. An absorbent article according to claim 1 or 2, characterized in that the compression section does not compress the top sheet.

6. An absorbent article according to claim 5, characterized in that a plurality of protrusions extending in the longitudinal direction are arranged at intervals in the width direction on the skin side of the top sheet.

7. An absorbent article according to claim 1 or 2, characterized in that the compression section compresses the top sheet together with the absorbent core.

8. An absorbent article according to claim 1 or 2, characterized in that the top sheet has through holes penetrating in the thickness direction of the top sheet.

9. An absorbent article as described in claim 1 or 2, characterized in that the skin side portion of the top sheet has a high basis weight region in which the basis weight of the fibers is high, and a low basis weight region in which the basis weight of the fibers is lower than that of the high basis weight region.

10. An absorbent article according to claim 9, characterized in that the high basis weight region protrudes closer to the skin than the low basis weight region.

11. An absorbent article as described in claim 1 or 2, characterized in that, when a test is conducted to measure the amount of rewet of the artificial urine returning to the top sheet when 40 ml of artificial urine is dropped onto the top sheet four times, the rewet amount is 1.0 g or less.

Images