Absorbent article

Abstract

Provided is an absorbent article which can easily keep the skin side dry even when a large amount of bodily fluid is discharged at a time, and which can suppress discomfort when worn due to a large thickness of the absorbent body. This absorbent article is provided with: a top sheet that comes into contact with the skin of a wearer in the front-rear direction, the width direction, and the thickness direction that are orthogonal to each other; and an absorbent body that is disposed further toward the non-skin side than the top sheet and that has an absorbent material that absorbs bodily fluids. The absorbent body has an upper absorbent layer and a lower absorbent layer disposed closer to the non-skin side than the upper absorbent layer. The absorbent material of the upper-side absorbent layer and the absorbent material of the lower-side absorbent layer contain fibers and a highly absorbent polymer. The density of the lower absorption layer is higher than that of the upper absorption layer. The weight ratio of the superabsorbent polymer to the weight of the entire absorbent material in the upper absorbent layer is 50% or more. The weight ratio of the superabsorbent polymer in the lower absorbent layer relative to the total weight of the absorbent material is 50% or more.

Description

[0001] This application is a divisional application of an application with an application date of March 20, 2025, an application number of 202510330623.3, and an invention title of "Absorbent Article". Technical Field

[0002] The present invention relates to an absorbent article having an upper absorbent layer and a lower absorbent layer. Background Art

[0003] In Patent Document 1, an absorber having fibers (fluff pulp) and a superabsorbent polymer is disclosed. The absorber has an upper absorbent layer and a lower absorbent layer. The upper absorbent layer has fibers and is formed to be relatively thick.

[0004] Prior art documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016-030100 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] Since the upper absorbent layer of Patent Document 1 has fibers and is formed to be relatively thick, there is a case where, when a large amount of body fluid is discharged at one time, the body fluid cannot be completely absorbed, and it is difficult to keep the surface on the skin side of the absorbent article dry. In addition, the thickness of the absorber is relatively thick due to the presence of fibers, and thus discomfort during wearing is likely to occur.

[0009] The present invention has been made in view of such problems, and provides an absorbent article that can easily keep the surface on the skin side of the absorbent article dry even when a large amount of body fluid is discharged at one time, and can suppress discomfort during wearing caused by the relatively thick thickness of the absorber.

[0010] Solutions to the Problems

[0011] An absorbent article of one embodiment includes: a longitudinal direction, a width direction, and a thickness direction, which are orthogonal to each other; a topsheet that abuts against the skin of the wearer; and an absorbent body that is disposed on the non-skin side with respect to the topsheet and has an absorbent material for absorbing body fluids. The absorbent body has an upper absorbent layer and a lower absorbent layer disposed on the non-skin side with respect to the upper absorbent layer. The absorbent material of the upper absorbent layer and the absorbent material of the lower absorbent layer include fibers and a superabsorbent polymer. The density of the lower absorbent layer is higher than the density of the upper absorbent layer. The weight ratio of the superabsorbent polymer with respect to the total weight of the absorbent material of the upper absorbent layer is 50% or more. The weight ratio of the superabsorbent polymer with respect to the total weight of the absorbent material of the lower absorbent layer is 50% or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 FIG. is a plan view of the absorbent article of Embodiment 1 as viewed from the skin side.

[0013] Figure 2 FIG. is a plan view of the absorbent article of Embodiment 1 as viewed from the non-skin side.

[0014] Figure 3 is a cross-sectional view taken along line A-A shown in Figure 1 FIG.

[0015] Figure 4 FIG. is a plan view of the intermediate absorbent layer.

[0016] Figure 5 FIG. is a plan view of the intermediate absorbent layer of a modified example.

[0017] REFERENCE SIGNS LIST

[0018] 1, absorbent article; 10, topsheet; 30, absorbent body; 31, upper absorbent layer; 32, lower absorbent layer; 33, intermediate absorbent layer; 34, opening; 80, compression part; R1, first region; R2, second region; R10, outer region; L, longitudinal direction; S1, crotch region; S2, front region; S3, rear region; T, thickness direction; T1, skin side; T2, non-skin side; W, width direction. DETAILED DESCRIPTION

[0019] (1) Summary of Embodiment

[0020] From the description of the present specification and the drawings, at least the following matters become clear.

[0021] The invention of Mode 1 is an absorbent article having: a front-back direction, a width direction, and a thickness direction, which are orthogonal to each other; a topsheet that abuts against the wearer's skin; and an absorber that is disposed on the non-skin side with respect to the topsheet and has an absorbent material for absorbing body fluids. The absorber has an upper absorber layer and a lower absorber layer disposed on the non-skin side with respect to the upper absorber layer. According to this mode, since both the upper absorber layer and the lower absorber layer have a relatively high weight ratio of superabsorbent polymer, the retention performance of retaining body fluids such as urine is high. Even when a large amount of body fluids are discharged at one time, it is easy to retain the body fluids, and it is easy to keep the surface on the skin side of the absorbent article dry. Since both the upper absorber layer and the lower absorber layer have a relatively low weight ratio of the fibers contained in the absorbent material, it is easy to make the thickness of the absorber thin. It is possible to suppress the discomfort during wearing caused by the thick thickness of the absorber. For the lower absorber layer, since the density is high and the voids between the fibers are few, it is possible to suppress the excessive swelling of the superabsorbent polymer, and it is possible to suppress the thickness of the absorber during swelling. Therefore, it is possible to suppress the change in the thickness of the lower absorber layer and ensure the bonding state with respect to the wearing article with respect to the fixing surface of the wearing article.

[0022] According to a preferred mode, for the invention of Mode 2, based on the invention of Mode 1, it may have the following features. The upper absorber layer has a plurality of sheets and a superabsorbent polymer disposed between the sheets. The superabsorbent polymer is joined to the sheets not by using an adhesive but by welding the plurality of sheets. According to this mode, since the superabsorbent polymer is joined by welding instead of using an adhesive, compared with the structure in which the upper absorber layer has an adhesive, it is possible to suppress the blocking of body fluids by the adhesive, and it is possible to improve the diffusibility of body fluids in the upper absorber layer and the transferability of body fluids to the lower absorber layer. In addition, compared with the structure in which the upper absorber layer has an adhesive, the fibers are not cured by the adhesive, and the superabsorbent polymer is easy to move in the absorber. The absorbed superabsorbent polymer can move in the planar direction and is easy to deform and conform to the body lines.

[0023] According to a preferred mode, for the invention of Mode 3, based on the invention of Mode 1 or Mode 2, it may have the following features. The lower absorber layer is not bonded by using an adhesive but is cured by winding the fibers around each other. Compared with the structure in which the lower absorber layer has an adhesive, the fibers are not cured by the adhesive, and the superabsorbent polymer is easy to move in the lower absorber layer. The absorbed superabsorbent polymer can move in the planar direction and is easy to deform and conform to the body lines.

[0024] According to a preferred embodiment, for the invention of Mode 4, based on the invention of any one of Modes 1 to 3, the following features may be provided. The thickness of the upper absorbent layer is thicker than the thickness of the lower absorbent layer. According to this mode, since the upper absorbent layer is relatively thick, the cushioning property is high and it has a thickness even after absorption. Thus, even when subjected to external forces such as body movements, it is easy to maintain its shape and the discomfort relative to the body can be reduced. In addition, since the lower absorbent layer is relatively thin, while maintaining the thinness of the absorbent body as a whole, it is easy to follow the deformation of the upper absorbent layer, and the discomfort during wearing and after absorption can be reduced.

[0025] According to a preferred embodiment, for the invention of Mode 5, based on the invention of any one of Modes 1 to 4, the following features may be provided. The bending stiffness of the lower absorbent layer is higher than the bending stiffness of the upper absorbent layer. According to this mode, since the bending stiffness of the upper absorbent layer is relatively low, the discomfort relative to the body can be reduced. In addition, the upper absorbent layer is easy to conform to the body lines. Since the bending stiffness of the lower absorbent layer is relatively high, it is easy to keep the non-skin side surface of the absorbent article flat, easy to be mounted on a wearing article such as underwear, and easy to maintain the joined state with respect to the wearing article.

[0026] According to a preferred embodiment, for the invention of Mode 6, based on the invention of any one of Modes 1 to 5, the following features may be provided. The tensile strength of the upper absorbent layer when wet is higher than the tensile strength of the lower absorbent layer when wet. According to this mode, the tensile strength of the upper absorbent layer when wet is high, and the deformation during use can be suppressed. Even in the case of long-term use or when a large amount of body fluid is absorbed, the deformation of the upper absorbent layer on the skin side can be suppressed, so the discomfort during wearing can be continuously suppressed.

[0027] According to a preferred embodiment, for the invention of Mode 7, based on the invention of any one of Modes 1 to 6, the following features may be provided. The absorbent body has an intermediate absorbent layer disposed between the upper absorbent layer and the lower absorbent layer. The intermediate absorbent layer is formed with an opening penetrating in the thickness direction and centrally disposed across the width direction in the crotch region of the absorbent article. The center in the width direction in the crotch region of the absorbent article is an area where it is easy to be disposed opposite to the excretory opening and easy to guide body fluid. According to this mode, the transfer of body fluid from the upper absorbent layer to the lower absorbent layer can be promoted by means of the opening of the intermediate absorbent layer.

[0028] According to a preferred embodiment, for the invention of Embodiment 8, based on the invention of Embodiment 7, the following features may be provided. The upper absorption layer and the lower absorption layer are joined within the opening portion. According to this embodiment, it is possible to suppress the positional deviation between the upper absorption layer and the lower absorption layer, and to suppress the thickness of the entire absorber and the discomfort during wearing. In addition, since the upper absorption layer and the lower absorption layer are closely attached within the opening portion, it is possible to promote the transfer of body fluid from the upper absorption layer to the lower absorption layer.

[0029] According to a preferred embodiment, for the invention of Embodiment 9, based on the invention of any one of Embodiments 1 to 8, the following features may be provided. The absorbent article has a compression portion formed by compressing the upper absorption layer and the lower absorption layer in the thickness direction. According to this embodiment, it is possible to join the upper absorption layer and the lower absorption layer using the compression portion, to suppress the positional deviation between the upper absorption layer and the lower absorption layer, and to suppress the thickness of the entire absorber and the discomfort during wearing. In addition, since the upper absorption layer and the lower absorption layer are joined by means of the compression portion, it is possible to promote the transfer of body fluid from the upper absorption layer to the lower absorption layer.

[0030] According to a preferred embodiment, for the invention of Embodiment 10, based on the invention of any one of Embodiments 1 to 9, the following features may be provided. The lower absorption layer is an absorber manufactured by wet-laid (wet method). In an absorber manufactured by wet-laid, there are fewer voids between fibers, it is possible to suppress the swelling of the superabsorbent polymer, and it is possible to suppress the absorber from becoming too thick.

[0031] According to a preferred embodiment, for the invention of Embodiment 11, based on the invention of Embodiment 10, the following features may be provided. There is a non-skin-side sheet that abuts against the non-skin-side surface of the lower absorption layer. The liquid diffusibility of the non-skin-side sheet is higher than that of the lower absorption layer. According to this embodiment, it is possible to promote the transfer of body fluid from the lower absorption layer to the non-skin-side sheet, to suppress the continuous accumulation of body fluid in the lower absorption layer made by the wet-laid manufacturing method and the separation between the fibers of the lower absorption layer, and to continuously maintain the shape of the lower absorption layer.

[0032] According to a preferred embodiment, for the invention of Embodiment 12, based on the invention of any one of Embodiments 1 to 11, the following features may be provided. The thickness of the lower absorption layer after absorbing body fluid with respect to the thickness before absorbing body fluid is 150% or less. According to this embodiment, it is possible to suppress the change in the shape and thickness of the lower absorption layer and ensure the fixing surface with respect to the wearing article, and to maintain the joined state with respect to the wearing article.

[0033] According to a preferred embodiment, for the invention of Mode 13, based on the invention of any one of Modes 1 to 12, the following features may be provided. The thickness of the absorber after absorbing body fluid is 300% or less relative to the thickness before absorbing body fluid. According to this mode, since the thickness does not become too thick when absorbing body fluid, discomfort caused by the thickening of the absorber can be suppressed.

[0034] According to a preferred embodiment, for the invention of Mode 14, based on the invention of any one of Modes 1 to 13, the following features may be provided. The permeability of the superabsorbent polymer in the upper absorbent layer is higher than that of the superabsorbent polymer in the lower absorbent layer. According to this mode, since the permeability of the superabsorbent polymer in the upper absorbent layer is high, body fluid can be quickly absorbed in the upper absorbent layer. By retaining body fluid using the upper absorbent layer, the absorption capacity of the lower absorbent layer can be continuously ensured. When body fluid is discharged repeatedly, body fluid can be absorbed in the lower absorbent layer, and body fluid can be continuously retained even after long-term use.

[0035] According to a preferred embodiment, for the invention of Mode 15, based on the invention of any one of Modes 1 to 14, the following features may be provided. The average interfiber distance of the lower absorbent layer is shorter than that of the upper absorbent layer. According to this mode, for the lower absorbent layer, the average interfiber distance is short and the voids between fibers are few, so the excessive swelling of the superabsorbent polymer can be suppressed, and the thickness of the absorber during swelling can be suppressed. Therefore, the change in the thickness of the lower absorbent layer can be suppressed, and the bonding state with respect to the wearing article can be maintained with respect to the fixing surface of the wearing article. In addition, since the interfiber distance of the lower absorbent layer is shorter than that of the upper absorbent layer, the transferability of body fluid from the upper absorbent layer to the lower absorbent layer can be improved. Body fluid guided to the upper absorbent layer can be diffused in the plane direction in the upper absorbent layer and then guided to the lower absorbent layer on the non-skin side, and can also be diffused in the plane direction in the lower absorbent layer.

[0036] According to a preferred embodiment, for the invention of Mode 16, based on the invention of any one of Modes 1 to 15, the following features may be provided. The thickness of the upper absorbent layer is less than 3 mm. The thickness of the lower absorbent layer is less than 2.5 mm. The overall thickness of the absorber is less than 6.5 mm. According to this mode, since the thicknesses of the upper absorbent layer and the lower absorbent layer are relatively thin, the absorber is easily deformed softly, the absorber easily conforms to the body, and discomfort during wearing can be suppressed. In addition, since the overall thickness of the absorber is relatively thin, discomfort when the side portion of the absorber touches the groin can be suppressed.

[0037] (2) Overall schematic structure of the absorbent article

[0038] Hereinafter, the absorbent article 1 of the embodiment will be described with reference to the drawings. Figure 1 FIG. 1 is a schematic top view of the absorbent article of the embodiment as viewed from the skin side. Figure 2 FIG. 2 is a schematic top view of the absorbent article of the embodiment as viewed from the non-skin side. Figure 3 FIG. 3 is a cross-sectional view taken along line A-A shown in Figure 1 . In Figure 3 , for ease of explanation, each component constituting the absorbent article 1 is partially separated in the thickness direction, but in an actual product, there are portions where the components are joined. In addition, in the following description of the drawings, the same or similar parts are labeled with the same or similar reference numerals. However, it should be noted that the drawings are schematic diagrams, and the ratios of the respective dimensions are different from the actual situation. Therefore, specific dimensions and the like should be determined with reference to the following description. Also, between the drawings, there may be portions where the relationships and ratios of the dimensions to each other are different.

[0039] The absorbent article 1 can be an absorbent article such as a sanitary napkin, a pantiliner, a urine absorbent pad, or a fecal pad. The absorbent article 1 can be an article used by being attached to a wearing article such as underwear. The absorbent article 1 of the embodiment is a urine absorbent pad. The absorbent article 1 is an absorbent article mainly for absorbing urine, and is not an absorbent article mainly for absorbing menstrual blood like a sanitary napkin nor an absorbent article mainly for absorbing leucorrhea like a pantiliner.

[0040] The absorbent article 1 has a front-back direction L and a width direction W that are orthogonal to each other, and has a thickness direction T that extends from the skin side T1 of the wearer to the non-skin side T2. The skin side T1 corresponds to the side facing the wearer's skin during use. The non-skin side T2 corresponds to the side opposite to the skin side T1 during use, that is, the side facing away from the wearer's skin. The absorbent article 1 has a crotch region S1, a front side region S2, and a rear side region S3. The crotch region S1 is a region disposed opposite to the excretory opening (urinary opening) of the wearer. When the absorbent article 1 is attached to underwear, the crotch region S1 is a region disposed in the crotch region of the underwear and between the wearer's legs. The crotch region S1 can be constituted by a region where the later-described wing portion 40 is disposed. The front side region S2 is located at a position forward of the crotch region S1. The rear side region S3 is located at a position rearward of the crotch region S1.

[0041] In addition, the outer part in the present invention refers to a part that occupies a certain range in the width direction W including the outer edge in the width direction W, and the outer edge refers to the outer edge in the width direction W. In addition, the outer edge of a constituent member that occupies a certain range in the front-rear direction L is an edge obtained by connecting the points on the outer side in the width direction W of the constituent member throughout the entire constituent member. The inner part in the present invention refers to a part that occupies a certain range in the width direction W including the inner edge in the width direction W, and the inner edge refers to the inner edge in the width direction W. In addition, the inner edge of a constituent member that occupies a certain range in the front-rear direction L is an edge obtained by connecting the points on the inner side in the width direction W of the constituent member throughout the entire constituent member. In addition, the front end part and the rear end part in the present invention are parts that occupy a certain range in the front-rear direction L including the edges in the front-rear direction L, and the front edge and the rear edge are the edges in the front-rear direction L. The outer end part includes the front end part and the rear end part, and the outer end edge includes the front edge and the rear edge. In addition, the inner side edge is an edge that includes the inner edge and extends along the front-rear direction L. The outer side edge is an edge that includes the outer edge and extends along the front-rear direction L. In addition, in this specification, the term "along the front-rear direction L" refers to a direction having an angle less than 45° with respect to the front-rear direction L, and the term "along the width direction W" refers to a direction having an angle less than 45° with respect to the width direction W.

[0042] The absorbent article 1 may at least have an absorber 30, a topsheet 10, and a backsheet 20. The topsheet 10 is a sheet material disposed at a position closer to the skin side T1 than the absorber 30 and in contact with the wearer. The topsheet 10 may have a top center sheet 11 that overlaps the center in the width direction W of the absorber 30, and a top side sheet 12 that overlaps the outer part in the width direction W of the top center sheet 11. The top side sheet 12 may also be disposed at a position closer to the skin side T1 than the top center sheet 11. The top side sheet 12 may cover the skin-side T1 surface of the top center sheet 11 and fold back toward the non-skin side with the outer part of the absorber 30 as a base point. The top side sheet 12 may cover a part of the non-skin side T2 surface of the absorber 30.

[0043] In a modified example, the topsheet 10 may be composed of a single sheet without the top center sheet 11 and the top side sheet 12. The top center sheet 11 and the top side sheet 12 may be made of non-woven fabric, or at least the top center sheet 11 has liquid permeability, and the surface of the top side sheet 12 is subjected to a hydrophobic treatment.

[0044] The absorbent article has an absorber 30 disposed on the non-skin side relative to the topsheet. The absorber 30 has an absorbent material for absorbing body fluids. The absorbent material includes fibers such as pulp and a superabsorbent polymer. The absorber 30 may have an upper absorber layer 31 and a lower absorber layer 32 disposed on the non-skin side relative to the upper absorber layer 31. The absorbent material of the upper absorber layer 31 and the absorbent material of the lower absorber layer 32 may include both fibers and a superabsorbent polymer. The absorber 30 may have an intermediate absorber layer 33 disposed between the upper absorber layer 31 and the lower absorber layer 32. The absorbent material of the intermediate absorber layer 33 may not have a superabsorbent polymer but have fibers. The absorbent material of the intermediate absorber layer 33 may have at least fibers. The structure of the absorber 30 will be described in detail later.

[0045] The absorbent article has a backsheet 20 disposed on the non-skin side T2 relative to the absorber 30 and forming the non-skin side surface of the absorbent article. The backsheet 20 may be liquid-impermeable and made of a film. In the absorbent article mounted on a wearing article, a fixing portion 60 for fixing the absorbent article 1 to an undergarment may be provided on the non-skin side surface of the backsheet 20. The fixing portion 60 may have a main body fixing portion 61 disposed at least in a region overlapping with the absorber 30 and a wing fixing portion 62 disposed on the wing portion 40. An adhesive or a hook-and-loop fastener may be provided on the fixing portion 60. Before using the absorbent article 1, the main body fixing portion 61 may be covered with a main body release sheet 65 (see Figure 2 ), and the wing fixing portion 62 may be covered with a wing release sheet (not shown).

[0046] The absorbent article 1 may have a second sheet 13. The second sheet 13 is disposed on the skin side T1 of the absorber 30 and at a position on the non-skin side T2 relative to the topsheet 10, and guides body fluids to the absorber 30. The length of the second sheet 13 in the front-rear direction L may be shorter than the length of the absorber 30 in the front-rear direction L. The outer end edge of the second sheet 13 may be located at a position on the inner side in the front-rear direction L relative to the outer end edge of the absorber 30. The outer side edge of the second sheet 13 may be located at a position on the inner side in the width direction W relative to the outer side edge of the absorber 30, and may be located at a position on the inner side in the width direction W relative to the outer side edge of the top center sheet 11. The second sheet 13 may be made of a non-woven fabric, and preferably may be made of a thermally-bonded non-woven fabric. In addition, the absorbent article 1 may not have the second sheet 13.

[0047] At least a compressed portion 80 formed by compressing the absorbent body 30 in the thickness direction T can be provided in the absorbent article 1. Regarding the compressed portion 80, the absorbent body 30 and the topsheet 10 may be compressed, or the absorbent body 30, the topsheet 10, and the second sheet 13 may be compressed together, or only the absorbent body 30 may be compressed. Preferably, the compressed portion 80 can be formed by compressing the topsheet 10, the absorbent body 30, and the second sheet 13 together from the skin side T1 side toward the non-skin side T2.

[0048] The absorbent article 1 may have a pair of wing portions 40 that extend to a position outside the absorbent body 30 in the width direction W and fold back toward the non-skin side of the underwear when worn. A pair of wing portions 40 may be provided at intervals in the width direction W. The wing portions 40 are disposed in the crotch region S1. It may be that the front edge of the wing portion 40 constitutes the front edge of the crotch region S1, and the rear edge of the wing portion 40 constitutes the rear edge of the crotch region S1. The side sheets 15 and the backsheet 20 may be disposed on the wing portions 40. The side sheet 15 is disposed at a position closer to the non-skin side than the top side sheet 12 disposed on the non-skin side of the absorbent body 30 and extends to a position outside the top side sheet 12 in the width direction.

[0049] The absorbent article 1 of the present embodiment is configured such that even when a large amount of body fluid is discharged at one time, it is easy to keep the skin-side surface of the absorbent article dry, and it is possible to suppress the discomfort during wearing caused by the relatively thick thickness of the absorbent body 30. Next, a structure for easily keeping the skin-side surface of the absorbent article dry even when a large amount of body fluid is discharged at one time and suppressing the discomfort during wearing caused by the relatively thick thickness of the absorbent body 30 will be described in detail.

[0050] The density of the lower absorbent layer 32 may be higher than the density of the upper absorbent layer 31. For the lower absorbent layer 32, since the density is relatively high and the voids between the fibers are relatively few, it is possible to suppress the excessive swelling of the superabsorbent polymer and suppress the thickness of the absorbent body 30 during swelling. Thus, it is possible to suppress the change in the thickness of the lower absorbent layer 32 and ensure the bonding state with respect to the wearing article with respect to the fixing surface of the wearing article.

[0051] Here, the density of each absorbent body is calculated based on the following formula.

[0052] D (g / cm 3 ) = B (g / m 2 ) / T (mm) × 10 -3

[0053] [In the formula, D, B, and T respectively represent the density, basis weight per unit area, and thickness of the absorbent body of the present invention.]

[0054] In addition, the basis weight (g / m 2 ) of the absorber 30 is calculated based on the following. Cut out three test pieces of 100 mm × 100 mm from each absorber 30, and measure the mass of each test piece under standard conditions (temperature 23 ± 2°C, relative humidity 50 ± 5%) using a direct-reading balance (for example, the electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.). The mass per unit area (g / m 2 ) of the absorber 30 calculated from the average of the three measured values is used as the basis weight of the absorber 30. In addition, regarding the measurement of the basis weight of the absorber 30, for the measurement conditions not specifically specified above, the measurement conditions described in ISO 9073-1 or JIS L1913 6.2 are adopted.

[0055] The thickness (mm) of the absorber 30 is measured as follows. Using a thickness gauge (for example, FS-60DS manufactured by Daisei Kagaku Kikai Seisakusho Co., Ltd., measuring surface 44 mm (diameter), measuring pressure 3 g / cm 2 ), apply a constant pressure of 3 g / cm 2 to five different positions of the absorber 30 under standard conditions (temperature 23 ± 2°C, relative humidity 50 ± 5%). (In the case of using the thickness gauge FS-60DS, the diameter of each position is 44 mm.) Measure the thickness 10 seconds after pressure application at each position, and use the average of the five measured values as the thickness of the absorber 30.

[0056] The weight ratio of the superabsorbent polymer in the upper absorbent layer 31 to the total weight of the absorbent material can be 50% or more. The weight ratio of the superabsorbent polymer in the lower absorbent layer 32 to the total weight of the absorbent material can be 50% or more. Since both the upper absorbent layer 31 and the lower absorbent layer 32 have a relatively high weight ratio of the superabsorbent polymer, the retention performance of body fluids such as urine is relatively high. Even when a large amount of body fluid is discharged at one time, it is easy to retain the body fluid, and it is easy to keep the skin side surface of the absorbent article 1 dry. Since the weight ratio of the fibers contained in the absorbent material is relatively low, it is easy to make the thickness of the absorber 30 relatively thin. The discomfort during wearing caused by the relatively thick thickness of the absorber 30 can be suppressed.

[0057] The weight ratio of the superabsorbent polymer in the upper absorbent layer 31 can be higher than the weight ratio of the superabsorbent polymer in the lower absorbent layer 32, and the weight per unit area of the superabsorbent polymer in the upper absorbent layer 31 can be higher than the weight per unit area of the superabsorbent polymer in the lower absorbent layer 32.

[0058] The upper absorbent layer 31 may have a plurality of sheets and superabsorbent polymers disposed between the sheets. That is, the upper absorbent layer 31 may be a so-called SAP sheet. The superabsorbent polymers may be joined to the sheets not by using an adhesive but by welding of the plurality of sheets. That is, the upper absorbent layer 31 may not have adhesives such as an adhesive for bonding the absorbent material, a solvent, etc. In the upper absorbent layer 31 of the present embodiment, by sandwiching the superabsorbent polymers with a hot air nonwoven fabric and performing heat treatment on the hot air nonwoven fabric, the superabsorbent polymers are welded to the hot air nonwoven fabric by melting of the fibers of the hot air nonwoven fabric. According to this method, since the superabsorbent polymers are joined by welding instead of using an adhesive, compared with the structure in which the upper absorbent layer 31 has an adhesive, the blocking of body fluids by the adhesive can be suppressed, and the diffusibility of body fluids in the upper absorbent layer 31 and the transferability of body fluids to the lower absorbent layer 32 can be improved. In addition, compared with the structure in which the upper absorbent layer 31 has an adhesive, the fibers are not cured by the adhesive, and the superabsorbent polymers are easily movable within the absorbent body 30. The absorbed superabsorbent polymers can move in the planar direction and are easily deformed and conformed along the lines of the body. The absorbent material of the upper absorbent layer 31 contains superabsorbent polymers. The absorbent material of the upper absorbent layer 31 may not have pulp, or may have pulp at a weight ratio less than that of the superabsorbent polymers.

[0059] It may be that the lower absorbent layer 32 is not bonded by using an adhesive but is cured by winding of the fibers with each other. That is, the lower absorbent layer 32 may not have adhesives such as an adhesive for bonding the absorbent material. The absorbent body 30 cured by winding of the fibers with each other can be manufactured, for example, by the following method: after forming a fiber laminate by a dry method or a wet method, performing crimping with a heating roll, or welding by air heating, or interlacing the fibers by using a high-pressure water stream. According to this method, compared with the structure in which the lower absorbent layer 32 has an adhesive, the fibers are not cured by the adhesive, and the superabsorbent polymers are easily movable within the lower absorbent layer 32. The absorbed superabsorbent polymers can move in the planar direction and are easily deformed and conformed along the lines of the body. The lower absorbent layer 32 of the present embodiment is an absorbent body 30 obtained by processing superabsorbent polymers and fibers by wet laid (wet method). According to the absorbent body 30 manufactured by wet laid, the voids between the fibers are less, the swelling of the superabsorbent polymers can be suppressed, and the thickness of the absorbent body 30 becoming too thick can be suppressed.

[0060] The liquid diffusibility of the non-skin side sheet that abuts against the non-skin side T2 surface of the lower absorbent layer 32 can be higher than that of the lower absorbent layer 32. This can promote the transfer of body fluid from the lower absorbent layer 32 to the non-skin side sheet. In particular, in the lower absorbent layer 32 made by the wet-laid process, it is possible to inhibit the continuous accumulation of body fluid within the lower absorbent layer 32 and the separation between the fibers of the lower absorbent layer 32, and the shape of the lower absorbent layer 32 can be continuously maintained. In the present embodiment, the non-skin side T2 surface at the center in the width direction W of the lower absorbent layer 32 abuts against the backsheet 20, and the non-skin side T2 surface at the side portion in the width direction W of the lower absorbent layer 32 abuts against the side sheet 15. The liquid diffusibility of the side sheet 15 can be higher than that of the lower absorbent layer 32.

[0061] The thickness of the upper absorbent layer 31 can be thicker than that of the lower absorbent layer 32. Since the upper absorbent layer 31 is relatively thick, it has higher cushioning properties and still has thickness after absorption. Thus, even when subjected to external forces such as body movements, it is easy to maintain its shape and can reduce discomfort relative to the body. In addition, since the lower absorbent layer is relatively thin, while maintaining the overall thinness of the absorbent body, it is easy to follow the deformation of the upper absorbent layer and can reduce discomfort during wearing and after absorption.

[0062] The thickness of the upper absorbent layer 31 can be less than 3 mm. The thickness of the lower absorbent layer 32 can be less than 2.5 mm. Since the thicknesses of the upper absorbent layer and the lower absorbent layer 32 are relatively thin, the absorbent body 30 is easy to deform softly, and the absorbent body 30 is easy to conform to the body, which can inhibit discomfort during wearing. In addition, the overall thickness of the absorbent body 30 can be less than 6.5 mm. Since the overall thickness of the absorbent body 30 is relatively thin, it is possible to inhibit discomfort when the side portion of the absorbent body 30 touches the groin. The overall thickness of the absorbent body 30 only needs to be the thickness obtained by adding the upper absorbent layer 31 and the lower absorbent layer 32, and the thickness obtained by adding the upper absorbent layer 31 and the lower absorbent layer 32 can be less than 6.5 mm, preferably less than 2 mm. The overall thickness of the absorbent body 30 can be the thickness obtained by adding the upper absorbent layer 31, the lower absorbent layer 32, and the intermediate absorbent layer 33, and the thickness of these three layers can be less than 6.5 mm, preferably less than 2 mm. In addition, the thickness of the lower absorbent layer 32 is preferably less than 1.0 mm, and more preferably 0.6 mm or less.

[0063] The thickness of the lower absorbent layer 32 after absorbing body fluid relative to the thickness before absorbing body fluid can be 150% or less. According to this mode, it is possible to suppress changes in the shape and thickness of the lower absorbent layer 32 and ensure the bonding state with respect to the fixing surface of the wearing article, and the bonding state with respect to the wearing article can be maintained. In addition, the thickness of the absorbent body 30 after absorbing body fluid relative to the thickness before absorbing body fluid can be 300% or less. According to this mode, since the thickness does not become too thick when absorbing body fluid, it is possible to suppress the discomfort caused by the thickening of the thickness of the absorbent body 30. Further, with respect to the thickness before absorbing body fluid, after the absorbent article 1 is taken out from the package, separation is performed by cold spraying using liquid nitrogen or the like, and the absorbent body is taken out from the absorbent article. For a portion without a compression portion or the like, samples are cut out in a size of 60 mm × 60 mm in combination with the width of the absorbent body, five such samples are prepared, the thickness is measured, and the average value of the five samples is taken. With respect to the thickness after absorbing body fluid, a specified amount of liquid (20 ml) is dropped onto the sample cut out by the above method using a dropper, the thickness after 5 minutes is measured, and the average value of the five samples is taken. The thickness of the absorbent body after absorbing body fluid relative to the thickness before absorbing body fluid is calculated by the thickness after absorbing body fluid / the thickness before absorbing body fluid.

[0064] The length in the width direction of the upper absorbent layer 31 and the length in the width direction of the lower absorbent layer 32 may be different. By making the length in the width direction of the upper absorbent layer 31 and the length in the width direction of the lower absorbent layer 32 different, the thickness of the outer portion in the width direction of the absorbent body is thinner, and it is possible to suppress the discomfort when the absorbent body touches the groin portion. In addition, the maximum length in the width direction of the upper absorbent layer 31 may be longer than the maximum length in the width direction of the lower absorbent layer 32, and may be longer than the maximum length in the width direction of the intermediate absorbent layer. In addition, the maximum length in the front-rear direction of the upper absorbent layer 31, the maximum length in the front-rear direction of the lower absorbent layer 32, and the maximum length in the front-rear direction of the intermediate absorbent layer may be substantially the same, and may be 95% or more and 105% or less with respect to the average length.

[0065] The bending stiffness of the lower absorbent layer 32 can be higher than that of the upper absorbent layer 31. Since the bending stiffness of the upper absorbent layer 31 is relatively low, the discomfort relative to the body can be reduced. In addition, the upper absorbent layer can easily conform to the body lines. Since the bending stiffness of the lower absorbent layer 32 is relatively high, it is easy to keep the non-skin side surface of the absorbent article flat, easy to install on a wearing article such as underwear, and easy to maintain the bonding state with respect to the wearing article. Here, the bending stiffness can be measured by the KES method. Specifically, it can be carried out using a KATO TECH Co., Ltd. KES-FB2-AUTO-A bending measurement testing machine, and samples capable of measuring the dimensions of the covering sheet and the inspection member are prepared. Regarding the bending stiffness of the inspection member, it is preferable to cut out the sample in a manner that includes the part where the antibody exists and measure the stiffness of the part containing the antibody. Next, each sample is fixed between the chucks of the measurement testing machine so that the lateral bending stiffness in each sample can be measured. Bend it to the front side until the maximum curvature is +2.5 cm-1, then bend it to the back side until the maximum curvature is -2.5 cm-1, and then restore it. The bending stiffness value is calculated based on the average of the inclination when starting to bend to the front side and the inclination of the bending moment with respect to the curvature is approximately constant and the inclination when starting to bend to the back side and the inclination of the bending moment with respect to the curvature is approximately constant. Repeat this 5 times for each sample, and use the average value as the bending stiffness.

[0066] The tensile strength of the upper absorbent layer 31 when wet can be higher than that of the lower absorbent layer 32 when wet. The relatively high tensile strength of the upper absorbent layer 31 when wet can inhibit deformation during use. Even during long-term use or when a large amount of body fluid is absorbed, the deformation of the upper absorbent layer 31 on the skin side can be inhibited, so the discomfort during wearing can be continuously inhibited. Preferably, the tensile strength of the upper absorbent layer 31 when wet can be 10 N / 25 cm or more. Here, the tensile strength can be measured using a tensile testing machine manufactured by INSTRON in a state where the sample to be measured is cut to a width of 25 mm and completely wetted with water.

[0067] The average interfiber distance of the lower absorbent layer 32 can be shorter than that of the upper absorbent layer 31. For the lower absorbent layer 32, the average interfiber distance is shorter and there are fewer voids between fibers. Therefore, the excessive swelling of the superabsorbent polymer can be suppressed, and the thickness of the absorbent body during swelling can be suppressed. Thus, the change in the thickness of the lower absorbent layer 32 can be suppressed, and the bonding state with respect to the wearing article can be maintained with respect to the fixing surface of the wearing article. In addition, since the interfiber distance of the lower absorbent layer 32 is shorter than that of the upper absorbent layer 31, the transferability of body fluid from the upper absorbent layer 31 to the lower absorbent layer 32 can be improved. The body fluid guided to the upper absorbent layer 31 can be diffused in the plane direction within the upper absorbent layer 31 and then guided to the lower absorbent layer 32 located on the non-skin side, and can also be diffused in the plane direction within the lower absorbent layer 32.

[0068] Regarding the evaluation of the average interfiber distance, for example, the average interfiber distance can be measured for the surface of the measurement object by using a microscope method, and the average interfiber distance can be measured for the non-skin side surface of the negative film 20 by using a microscope method. For the microscope method, a magnified image with consistent focus is obtained from the skin side surface of the specimen to a depth of 100 μm by using the 3D image connection function of a microscope (KEYENCE VHX-2000, lens VH-Z20W with aperture open), and the outer sides of the fibers with consistent focus are extracted based on this magnified image. The surface formed here is taken as the fiber space. The diameter of the largest inscribed circle of this fiber space is taken as the fiber space distance, and the average value of the quantity at 100 fiber spaces is taken as the average interfiber distance.

[0069] The permeability of the superabsorbent polymer in the upper absorbent layer 31 can be higher than that in the lower absorbent layer 32. Since the permeability of the superabsorbent polymer in the upper absorbent layer 31 is higher, body fluid can be quickly absorbed in the upper absorbent layer 31. By retaining body fluid using the upper absorbent layer 31, the absorption capacity of the lower absorbent layer 32 can be continuously ensured. When body fluid is repeatedly discharged, body fluid can be absorbed in the lower absorbent layer 32, and body fluid can be continuously retained even after long-term use.

[0070] The permeability of a superabsorbent polymer can be evaluated, for example, using a permeability evaluation device. The evaluation of permeability using the permeability evaluation device is carried out as follows. (i) Place the sample to be measured on a specimen stage with an inclination of 10°. For the sample, measurement is carried out in a state where 10 g of the superabsorbent polymer to be measured is clamped by non-woven fabric sheets of the same type and is being clamped by the non-woven fabric sheets. A circular hole with a diameter of 65 mm is provided on the surface of the specimen stage where the sample is placed. (ii) Using a tube with a diameter of 5 mm, 100 ml of artificial urine is dropped from a height of 80 mm within 3.75 seconds. The dropped artificial urine passes through the sample and enters the collection dish through the hole in the specimen stage.

[0071] (iii) Measure the weight of the artificial urine that has entered the collection dish.

[0072] (iv) Calculate the permeability according to the following formula.

[0073] Permeability (%) = Weight of artificial urine entering the collection dish (g) / 25 (g) × 100

[0074] A superabsorbent polymer with a higher permeability has a higher permeability, and a superabsorbent polymer with a lower permeability has a lower permeability.

[0075] The compression part 80 can compress the upper absorbent layer 31 and the lower absorbent layer 32 in the thickness direction. According to this embodiment, the upper absorbent layer 31 and the lower absorbent layer 32 are joined by the compression part 80. By joining the upper absorbent layer 31 and the lower absorbent layer 32 using the compression part 80, it is possible to suppress the positional deviation of the upper absorbent layer 31 and the lower absorbent layer 32, and to suppress the thickness of the entire absorbent body and the discomfort during wearing. In addition, since the upper absorbent layer 31 and the lower absorbent layer 32 are joined by the compression part 80, it is possible to promote the transfer of body fluid from the upper absorbent layer 31 to the lower absorbent layer 32. Further, in the region overlapping with the intermediate absorbent layer, it is possible that the compression part compresses the upper absorbent layer 31, the intermediate absorbent layer 33, and the lower absorbent layer 32 together to join the upper absorbent layer 31, the intermediate absorbent layer 33, and the lower absorbent layer 32.

[0076] Figure 4 is a plan view of the intermediate absorbent layer 33. The intermediate absorbent layer 33 may be formed with an opening 34 that penetrates the intermediate absorbent layer 33 in the thickness direction. The opening 34 is disposed across the center in the width direction W in the crotch region S1 of the absorbent article 1. The center in the width direction W in the crotch region S1 of the absorbent article 1 is a region that is easily disposed opposite to the excretion port and is easily guided to the body fluid. According to this embodiment, it is possible to promote the transfer of body fluid from the upper absorbent layer 31 to the lower absorbent layer 32 by means of the opening 34 of the intermediate absorbent layer 33. The opening 34 is such that the weight per unit area of the fibers in the absorbent material is 0 g / m3 portion. In addition, the basis weight of the fiber is 0 g / m² 3 portion as long as the designed basis weight is 0 g / m² 3 is sufficient, and fibers floating down from the surroundings may also be arranged. In addition, a superabsorbent polymer may be arranged in the opening 34 of the present embodiment. A structure in which a superabsorbent polymer is arranged in the opening will be described later.

[0077] It is sufficient that at least a part of the opening 34 is arranged in the crotch region S1, and it may straddle the front side region S2 or the rear side region S3. The center of the opening 34 in the front-rear direction L may be located at a position closer to the front side than the center of the crotch region S1 in the front-rear direction L. In terms of the excretion port, it is easy to be arranged opposite to the region closer to the front side than the center of the crotch region S1 in the front-rear direction L, and by the center of the opening 34 in the front-rear direction L being located at a position closer to the front side than the center of the crotch region S1 in the front-rear direction L, it is easier to introduce body fluid into the opening 34 more smoothly. The maximum width of the opening 34 may be 50% or more with respect to the entire width direction W of the intermediate absorbent layer 33, and may be 50% or more with respect to the entire width direction W of the absorbent body 30.

[0078] The upper absorbent layer 31 and the lower absorbent layer 32 may be joined within the opening 34. It is possible to suppress the positional deviation of the upper absorbent layer 31 and the lower absorbent layer 32, and to suppress the overall thickness of the absorbent body 30 and the discomfort during wearing. In addition, since the upper absorbent layer 31 and the lower absorbent layer 32 are in close contact within the opening 34, it is possible to promote the transfer of body fluid from the upper absorbent layer 31 to the lower absorbent layer 32.

[0079] The absorbent body has an open absorbent layer in which an opening 34 penetrating in the thickness direction is formed. The opening 34 is provided in the intermediate absorbent layer 33, and the intermediate absorbent layer 33 constitutes the "open absorbent layer" of the present invention. In addition, although the "open absorbent layer" is constituted by the intermediate absorbent layer 33 in the present embodiment, in a modified example, it may be constituted by at least any one of the upper absorbent layer 31 and the lower absorbent layer 32. The opening 34 has a first region R1 and a second region R2, and the second region R2 is arranged outside the first region R1 in the front-rear direction L, and the length in the width direction is longer than the length in the width direction of the first region. The first region R1 and the second region R2 are regions adjacent in the front-rear direction L within one opening 34. The maximum width of the second region R2 is longer than the maximum width of the first region R1. In a manner where the length in the width direction W of the opening 34 gradually changes as in the present embodiment, the midpoint between the position with the shortest maximum width and the position with the longest maximum width can be used as the boundary between the first region R1 and the second region R2. Figure 4Indicates the boundary between the first region R1 and the second region R2. By having the first region R1 and the second region R2 with different lengths in the width direction W in the opening 34, when a force directed inward in the width direction due to a leg or the like is applied, even if the first region R1 is crushed, the second region R2 is not easily crushed, and the overall crushing of the opening 34 can be suppressed.

[0080] A superabsorbent polymer can be disposed in the opening 34. Instead of disposing fibers such as pulp in the opening 34, a superabsorbent polymer can be disposed. The superabsorbent polymer in the opening 34 can be used to hold body fluids. Since no fibers such as pulp are disposed in the opening 34 but a superabsorbent polymer is disposed, the diffusion rate of body fluids can be suppressed from decreasing due to the presence of fibers, and the absorption capacity of body fluids can be ensured using the superabsorbent polymer. In addition, the opening 34 is disposed at the center in the width direction W in the crotch region S1 of the absorbent article 1 and in a region opposite to the excretory opening. By disposing a superabsorbent polymer in the opening that can easily guide body fluids from the excretory opening, the holding performance of holding body fluids such as urine can be improved.

[0081] The weight per unit area of the superabsorbent polymer in the opening 34 can be lower than the weight per unit area of the superabsorbent polymer in the surrounding region of the opening 34 in the opening absorbent layer. Since the weight per unit area of the superabsorbent polymer in the opening 34 is lower, gel blockage at the opening 34 is suppressed, and the transfer of body fluids from the opening 34 to the non-skin side is not easily hindered. Since the weight per unit area of the superabsorbent polymer in the intermediate absorbent layer around the opening 34 is higher, body fluids are easily held in the surrounding region, and the absorption capacity can be ensured.

[0082] The absorbent body 30 can have a covering sheet that covers the opening 34. It is easy to suppress the deformation of the opening 34 due to the presence of the covering sheet, and it is easy to maintain the shape of the opening 34. In addition, the covering sheet only needs to cover at least a part of the opening 34, but preferably can cover the entire region of the opening 34. The covering sheet can be disposed on the skin side T1 of the opening absorbent layer having the opening 34, or can be disposed on the non-skin side T2 of the opening absorbent layer. The covering sheet of the present embodiment is composed of a sheet disposed in the upper absorbent layer 31 while sandwiching the superabsorbent polymer, and covers the entire region of the skin side T1 of the opening 34.

[0083] The absorbent body 30 can have a covering absorbent layer that is disposed overlapping the opening 34 and has a superabsorbent polymer. When the superabsorbent polymer in the covering absorbent layer absorbs body fluids, it swells, thereby supporting the opening 34, easily suppressing the deformation of the opening 34, and ensuring the area of the opening 34. In addition, the covering absorbent layer only needs to cover at least a part of the opening 34, but preferably can cover the entire region of the opening 34.

[0084] The covering absorbent layer can be disposed on the skin side T1 of the open absorbent layer having the opening 34, or can be disposed on the non-skin side T2 of the open absorbent layer. Preferably, the covering absorbent layer can be respectively disposed on the skin side T1 and the non-skin side T2 of the opening 34. According to this mode, since the covering absorbent layer is disposed so as to sandwich the opening 34, it is easier to maintain the shape of the opening 34. The covering absorbent layer of the present embodiment is composed of an upper absorbent layer 31 and a lower absorbent layer 32, and covers the entire regions of the skin side T1 and the non-skin side T2 of the opening 34.

[0085] A colored layer can be disposed on the non-skin side of the opening 34. The colored layer can be configured to be visually recognizable from the surface of the skin side T1 of the absorbent article 1. In addition, "visually recognizable" means a case where a subject with good eyesight (1.0 or more) can visually recognize an object at a distance of about 30 cm to 50 cm in a room brightly illuminated with daylight color (color temperature reference value 4600K to 5400K (Kelvin)) (reference value: 500 lx to 750 lx (lux)). According to this mode, the user can easily notice the existence of the opening 34 by visually recognizing the colored layer from the skin side T1 of the absorbent article 1 through the opening 34. The colored layer of the present embodiment is composed of the lower absorbent layer 32.

[0086] The compression part 80 can straddle the outer edge of the opening 34. According to this mode, it is easy to use the compression part 80 to increase the stiffness of the outer edge of the opening 34 and to maintain the shape of the opening 34. The compression part 80 only needs to straddle at least a part of the outer edge of the opening 34. Preferably, the compression part 80 can straddle the side edges located on the outer side in the width direction W and extending in the front-rear direction L of the outer edge of the opening 34. More preferably, the compression part 80 can straddle the side edges located on both sides in the width direction W of the outer edge of the opening 34. In the present embodiment, a plurality of compression parts 80 are provided at intervals in the front-rear direction L along the side edges of the opening 34. According to this structure, it is easy to suppress the side edges on both sides of the opening 34 from entering the inside, and it is easier to ensure the area of the opening 34. The compression part 80 can have a compression part straddling the outer edge of the opening 34 and a compression part separated from the outer edge of the opening and located at a position outside the outer edge of the opening in the width direction. The compression part straddling the outer edge of the opening 34 can be used to maintain the shape of the opening and improve the introduction of body fluid to the non-skin side, and the compression part located at a position outside the outer edge of the opening in the width direction can be used to improve the introduction of body fluid diffused to the outside in the width direction, and side leakage can be suppressed.

[0087] The open absorbent layer may have outer regions R10 located respectively at positions outside the outer edges on both sides in the width direction of the opening 34. The fixing portions may be respectively disposed in regions overlapping with the outer regions R10. The outer region R10 is the region between the outer edge of the opening 34 and the outer edge of the open absorbent layer. The "fixing portion" in the present embodiment is constituted by a main body fixing portion. The main body fixing portion 61 is disposed in a region overlapping with the outer region R10. According to this mode, by pressing the outer regions R10 located outside the width direction of the opening 34 toward the wearing article side respectively, the two outer edges of the opening 34 are not easily moved inward in the width direction, so that the shape of the opening 34 is easily maintained. The main body fixing portion 61 as the fixing portion may straddle the outer edge of the opening 34. According to this mode, it is easy to use the main body fixing portion 61 to suppress the situation where the outer edge of the opening 34 enters the inside, and it is easy to ensure the area of the opening 34. The length in the width direction of the opening 34 at the position of the maximum length in the width direction of the opening 34 may be longer than the length in the width direction of each outer region R10. Preferably, the length in the width direction of the opening 34 at the position of the maximum length in the width direction of the opening 34 may be 60% or more, preferably 70% or more, relative to the length in the width direction of the intermediate absorbent layer. The opening can be set to a larger width, and the transferability of body fluid to the non-skin side can be improved by means of the opening.

[0088] A plurality of the first regions R1 and the second regions R2 may be alternately arranged respectively in the front-rear direction L. That is, it may be that the first region R1, the second region R2, the first region R1, and the second region R2 are arranged along the front-rear direction L. According to this mode, when a force toward the inside in the width direction W is applied, the plurality of first regions R1 can be used to absorb the force, the opening state of the plurality of second regions R2 can be maintained, and the situation where the entire opening 34 is crushed can be suppressed.

[0089] Next, with reference to Figure 5 the opening 34X of the modification will be described. Figure 5 is a plan view of the intermediate absorbent layer 33X which is the open absorbent layer of the modification. In addition, in the following description of the modification, the same reference numerals are used for the same structures as those in the above-described embodiment and the description thereof is omitted. For the opening 34 of the embodiment, the first region and the second region are alternately arranged, and the outer edge of the opening is wavy. In contrast, the opening 34X of the modification is in a water droplet shape in plan view, and the outer edge of the opening 34X is a curved shape bulging outward. In addition, for the opening 34X of the modification, one second region R2 is disposed so as to be sandwiched by the first regions R1. In the water droplet-shaped opening 34X of the modification, there are the first region R1 and the second region R2. Even when a force is applied from the side during wearing and the width of the opening becomes narrower, body fluid is easily introduced into the opening, and the introduction property of the body fluid is easily maintained.

[0090] As described above, the present invention has been described in detail using the above-described embodiments. However, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as a modification and variation without departing from the gist and scope of the present invention determined by the claims. Therefore, the description in this specification is for illustrative purposes and does not have any restrictive meaning for the present invention.

Claims

1. An absorbent article, comprising: a front-to-back direction, a width direction, and a thickness direction, which are orthogonal to each other; a top sheet, which contacts the skin of a wearer; and an absorbent body, which is arranged at a position closer to the non-skin side than the top sheet, and has an absorbent material for absorbing body fluids, wherein the absorbent body has an upper absorbent layer and a lower absorbent layer arranged at a position closer to the non-skin side than the upper absorbent layer, wherein: The absorbent material of the upper absorbent layer and the absorbent material of the lower absorbent layer contain fibers and superabsorbent polymers, The density of the lower absorbent layer is higher than that of the upper absorbent layer, The weight ratio of the superabsorbent polymer in the upper absorbent layer relative to the weight of the entire absorbent material is 50% or more. The weight ratio of the superabsorbent polymer in the lower absorbent layer relative to the weight of the entire absorbent material is 50% or more.

2. The absorbent article according to claim 1, wherein The upper absorbent layer has a plurality of sheets and a high absorbent polymer disposed between the sheets. The superabsorbent polymer is joined to the sheet material not by an adhesive but by welding the plurality of sheets.

3. The absorbent article according to claim 2, wherein: The lower absorbent layer is not bonded by an adhesive but is solidified by entanglement of fibers.

4. The absorbent article according to any one of claims 1 to 3, wherein The thickness of the upper absorbent layer is thicker than that of the lower absorbent layer.

5. The absorbent article according to any one of claims 1 to 3, wherein The lower absorbent layer has a higher bending rigidity than the upper absorbent layer.

6. The absorbent article according to any one of claims 1 to 3, wherein The tensile strength of the upper absorbent layer when wet is higher than the tensile strength of the lower absorbent layer when wet.

7. The absorbent article according to any one of claims 1 to 3, wherein The absorbent body includes an intermediate absorbent layer disposed between the upper absorbent layer and the lower absorbent layer. The intermediate absorbent layer has an opening formed therein and extending through the absorbent article in the thickness direction and arranged across the center in the width direction of the crotch region of the absorbent article.

8. The absorbent article according to claim 7, wherein: The upper absorbent layer and the lower absorbent layer are joined in the opening.

9. The absorbent article according to any one of claims 1 to 3, wherein The absorbent article includes a compressed portion formed by compressing the upper absorbent layer and the lower absorbent layer in a thickness direction.

10. The absorbent article according to any one of claims 1 to 3, wherein The lower absorbent layer is an absorbent body produced by wet-laid web formation, ie, a wet method.

11. The absorbent article according to claim 10, wherein The absorbent article includes a non-skin side sheet that contacts the non-skin side surface of the lower absorbent layer. The liquid diffusivity of the non-skin side sheet is higher than the liquid diffusivity of the lower absorbent layer.

12. The absorbent article according to any one of claims 1 to 3, wherein The thickness of the lower absorbent layer after body fluid absorption is 150% or less of the thickness before body fluid absorption.

13. The absorbent article according to any one of claims 1 to 3, wherein The thickness of the absorbent body after absorption of body fluids is 300% or less relative to the thickness before absorption of body fluids.

14. The absorbent article according to any one of claims 1 to 3, wherein The permeability of the superabsorbent polymer of the upper absorbent layer is higher than the permeability of the superabsorbent polymer of the lower absorbent layer.

15. The absorbent article according to any one of claims 1 to 3, wherein The average inter-fiber distance of the lower absorbent layer is shorter than the average inter-fiber distance of the upper absorbent layer.

16. The absorbent article according to any one of claims 1 to 3, wherein The thickness of the upper absorbent layer is less than 3 mm. The thickness of the lower absorbent layer is less than 2.5 mm, The overall thickness of the absorbent body is less than 6.5 mm.

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