Absorbent article

Abstract

Provided is an absorbent article (1) having an upper layer core (31) and a lower layer core (32), wherein: the upper layer core (31) has a groove (35) which is depressed in the thickness direction and has a length in a prescribed direction; the upper layer core (31) has a groove region in which the groove (35) is provided and a non-groove region in which the groove (35) is not provided; at least some of the groove region is provided in a region where the upper layer core (31) and the lower layer core (32) overlap in a view from the thickness direction; and the average density of a highly absorbent polymer (34) in a skin-side part of the groove region is lower than the average density of the highly absorbent polymer (34) in a skin-side part of the non-groove region.

Description

Technical Field

[0001] The present invention relates to absorbent articles.

Background Art

[0002] Patent Document 1 discloses an absorbent article including an absorber having a two-layer structure of an upper absorber and a lower absorber. At least a slit penetrating the upper absorber in the thickness direction is provided at the center in the width direction of the upper absorber. Further, the weight ratio of the superabsorbent polymer to the pulp fiber is higher in the upper absorber than in the lower absorber. By doing so, excreted liquid is supplied to both the upper absorber and preferentially supplied to the lower absorber through the slit. The liquid absorbed by the lower absorber is sucked up by the upper absorber and retained by the superabsorbent polymer in the upper absorber after the lower absorber is saturated with absorption. Therefore, it is said to be excellent in preventing rewetting.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, if a relatively large slit is provided in the upper absorber (upper core) as in Patent Document 1, excreted liquid is locally spot-absorbed in the portion of the lower absorber (lower core) facing the slit. There is a limit to the range in which the excreted liquid diffuses from the spot-absorbed portion, and the excreted liquid cannot be absorbed over a wide range of the lower absorber. The upper absorber can also suck up the excreted liquid only in the range where the excreted liquid has diffused in the lower absorber and is not effectively utilized. Further, in the portion where a large slit is provided in the upper absorber, the excreted liquid absorbed by the lower absorber is not sucked up by the upper absorber and flows back, easily touching the skin, and the rewetting prevention property is also insufficient.

[0005] Therefore, the present invention has been made in view of the above problems, and an object thereof is to enhance the diffusibility of excreted liquid in the upper core and the lower core while suppressing rewet in an absorbent article in which the upper core and the lower core are laminated.

Means for Solving the Problems

[0006] The main invention for achieving the above object is an absorbent article having a longitudinal direction, a width direction, and a thickness direction and having an absorbent core, wherein the absorbent core has an upper core having a superabsorbent polymer and a lower core disposed on the non-skin side in the thickness direction with respect to the upper core, the upper core has a groove in which a part of the upper core is recessed in the thickness direction, the groove has a length in a predetermined direction, the upper core has a groove region where the groove is provided and a non-groove region where the groove is not provided when viewed in the thickness direction, at least a part of the groove region is provided in a region where the upper core and the lower core overlap when viewed in the thickness direction, when the upper core is divided into two in the thickness direction, a part located on the skin side is defined as a skin-side part and a part located on the non-skin side is defined as a non-skin-side part, the average density of the superabsorbent polymer in the skin-side part of the groove region is lower than the average density of the superabsorbent polymer in the skin-side part of the non-groove region, The absorbent core is partitioned by dividing its maximum width into three equal parts in the width direction, and has a central portion in the width direction and a pair of side portions in the width direction. The absorbent article in the unfolded and stretched state has a front portion located on the front side in the longitudinal direction with respect to a center line that bisects the absorbent article in the longitudinal direction, and a rear portion located on the rear side in the longitudinal direction with respect to the center line. The rear portion has a first rear region that is a central region when its maximum length is divided into three equal parts in the longitudinal direction. The front portion has a first front region that is a central region when its maximum length is divided into three equal parts in the longitudinal direction. The value obtained by dividing the area of the groove region of the upper layer core located at the central portion in the width direction of the first rear region by the area of the central portion in the width direction of the first rear region is smaller than the value obtained by dividing the area of the groove region of the upper layer core located at the central portion in the width direction of the first front region by the area of the central portion in the width direction of the first front region. The central portion in the width direction of the first rear region has a higher average basis weight of the absorbent core than the pair of side portions in the width direction of the first rear region. The upper layer cores respectively located at the pair of side portions in the width direction of the first rear region have the grooves having a length in the longitudinal direction which is the predetermined direction. which is characterized by the absorbent article. Other features of the present invention will be clarified by the description in this specification and the accompanying drawings. [Effect of the Invention]

[0007] According to the present invention, in an absorbent article in which an upper core and a lower core are laminated, it is possible to suppress rewet while enhancing the diffusibility of excreted liquid in the upper core and the lower core. [Brief Description of the Drawings]

[0008]

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[0009] At least the following matters become clear from the description of this specification and the accompanying drawings. An absorbent article having a longitudinal direction, a width direction, and a thickness direction and having an absorbent core, wherein the absorbent core has an upper core having a superabsorbent polymer and a lower core disposed on the non-skin side in the thickness direction with respect to the upper core, the upper core has a groove in which a part of the upper core is recessed in the thickness direction, the groove has a length in a predetermined direction, the upper core has a groove region provided with the groove and a non-groove region not provided with the groove when viewed in the thickness direction, at least a part of the groove region is provided in a region where the upper core and the lower core overlap when viewed in the thickness direction, when the upper core is divided into two in the thickness direction and the part located on the skin side is defined as the skin-side part and the part located on the non-skin side is defined as the non-skin side part, the average density of the superabsorbent polymer in the skin-side part of the groove region is lower than the average density of the superabsorbent polymer in the skin-side part of the non-groove region. An absorbent article characterized by this.

[0010] According to such an absorbent article, excreted liquid discharged to the skin side of the upper core easily flows (is easily absorbed) into the groove region where the average density of the superabsorbent polymer is low, and is diffused in a predetermined direction along the groove region. Since the lower core receives and absorbs the excreted liquid diffused by the upper core, the excreted liquid is absorbed over a wide range of the lower core. Therefore, the diffusibility of the excreted liquid in the upper core and the lower core is high, and the absorption amount of the absorbent core can be increased. In addition, since the excreted liquid absorbed on the skin side portion of the non-groove region of the upper core is retained by the superabsorbent polymer, rewetting of the excreted liquid on the skin side surface of the upper core can be suppressed.

[0011] Such an absorbent article, wherein the absorbent core has a central portion in the width direction and a pair of side portions in the width direction, which are partitioned by dividing its maximum width into three equal parts in the width direction, and has a front side portion located on the front side in the longitudinal direction with respect to a center line that bisects the absorbent article in the longitudinal direction in a deployed and stretched state, and a rear side portion located on the rear side in the longitudinal direction with respect to the center line, the rear side portion has a rear side first region that is a central region when its maximum length is divided into three equal parts in the longitudinal direction, the front side portion has a front side first region that is a central region when its maximum length is divided into three equal parts in the longitudinal direction, and a value obtained by dividing the area of the groove region of the upper core located at the central portion in the width direction of the rear side first region by the area of the central portion in the width direction of the rear side first region is smaller than a value obtained by dividing the area of the groove region of the upper core located at the central portion in the width direction of the front side first region by the area of the central portion in the width direction of the front side first region. An absorbent article characterized by this.

[0012] According to such an absorbent article, in the central portion in the width direction of the rear side first region where the body pressure of the wearer is likely to be applied, since the area ratio of the groove region is small, the amount of excreted liquid rewetting from the groove region can be reduced. On the other hand, in the front side first region, which is a portion in contact with or near the excretory opening, since the area ratio of the groove region is large, a large amount of excreted liquid can be quickly diffused and drawn into the absorbent core, suppressing leakage of the excreted liquid.

[0013] An absorbent article, wherein the upper layer core located at the center in the width direction of the rear first region has a region where only one groove having a length in the longitudinal direction, which is the predetermined direction, is located.

[0014] According to such an absorbent article, in the central portion in the width direction of the rear first region where the body pressure of the wearer is likely to be applied, since there is a region where a plurality of groove regions are not arranged in the width direction, rewet can be suppressed. Further, the excreted liquid flowing from the excretory opening contact portion to the rear first region can be drawn into the absorbent core while diffusing in the longitudinal direction in the groove region, and leakage of the excreted liquid can be suppressed.

[0015] An absorbent article, wherein the central portion in the width direction of the rear first region has a higher average basis weight of the absorbent core than the pair of widthwise side portions of the rear first region, and the upper layer cores respectively located at the pair of widthwise side portions of the rear first region have grooves having a length in the longitudinal direction, which is the predetermined direction.

[0016] According to such an absorbent article, in the central portion in the width direction of the rear first region where the body pressure of the wearer is likely to be applied, the water absorption and retention power of the excreted liquid is increased, so that rewet can be suppressed. Further, the excreted liquid flowing from the excretory opening contact portion to the rear first region can be drawn into the absorbent core while diffusing in the longitudinal direction in the groove region of the widthwise side portion, and leakage (lateral leakage) of the excreted liquid can be suppressed.

[0017] An absorbent article, wherein the rear portion has a rear second region on the front side in the longitudinal direction of the rear first region, the front portion has a front second region on the rear side in the longitudinal direction of the front first region, and between the groove regions of the upper layer core located in the rear second region and the groove regions of the upper layer core located in the front second region in the longitudinal direction, the upper layer core has a region where the non-groove region is continuous from one end to the other end in the width direction.

[0018] According to such an absorbent article, a large amount of excretory fluid can be quickly diffused and drawn into the absorbent core by the groove region of the front second region, which is the excretory opening contact portion or a portion near it. The absorbed excretory fluid can be retained in the non-groove region, and rewet can be suppressed. In addition, the excretory fluid that flows to the rear side without being completely absorbed in the front second region can be diffused by the groove region of the rear second region and absorbed into the absorbent core, so that leakage of the excretory fluid can be suppressed.

[0019] Such an absorbent article, wherein the rear portion has a rear second region on the front side in the longitudinal direction than the rear first region, and the area of the groove region of the upper layer core located at the center in the width direction of the rear second region, when divided by the area of the center in the width direction of the rear second region, is larger than the value obtained by dividing the area of the groove region of the upper layer core located at the center in the width direction of the rear first region by the area of the center in the width direction of the rear first region.

[0020] According to such an absorbent article, in the central portion in the width direction of the rear first region where the body pressure of the wearer is likely to be applied, since the area ratio of the groove region is small, rewet can be suppressed. On the other hand, in the rear second region, which is a portion close to the excretory opening contact portion, since the area ratio of the groove region is large, the excretory fluid can be quickly diffused and drawn into the absorbent core, and leakage of the excretory fluid can be suppressed.

[0021] Such an absorbent article, wherein the front portion has a front second region on the rear side in the longitudinal direction than the front first region, and the upper layer core located at the center in the width direction of the front first region has more grooves having a length in the longitudinal direction, which is the predetermined direction, than the upper layer core located at the center in the width direction of the front second region.

[0022] According to such an absorbent article, compared with the front-side second region that contacts the wearer's crotch, the front-side first region is less likely to be subjected to the body pressure of the wearer. Therefore, even if the number of grooves is large, it is difficult to rewet. Further, when the wearer is male, since the front-side first region becomes a part that contacts or is close to the excretion opening contact portion, a large number of grooves can diffuse the excreted liquid in the longitudinal direction and draw it into the absorbent core, thereby suppressing leakage of the excreted liquid.

[0023] Such an absorbent article, wherein the absorbent article has a pair of leak-preventing wall portions that can stand up on the skin side at both side portions in the width direction of the absorbent core, and when the absorbent article in the deployed and stretched state is viewed in the thickness direction, the upper layer core has a groove region at least partially overlapping with the leak-preventing wall portions.

[0024] According to such an absorbent article, the excreted liquid blocked by the leak-preventing wall portion can be absorbed into the absorbent core while diffusing in the groove region. Further, at the site where the leak-preventing wall portion exists, the leak-preventing wall portion functions as a buffer material and it is difficult for body pressure to be applied, so that rewetting of the groove region can be suppressed.

[0025] Such an absorbent article, wherein the lower layer core has a superabsorbent polymer, and the average density of the superabsorbent polymer in the upper layer core is higher than the average density of the superabsorbent polymer in the lower layer core.

[0026] According to such an absorbent article, even if the excreted liquid absorbed by the lower layer core rewets the upper layer core, the excreted liquid is retained by the superabsorbent polymer in the upper layer core, so that rewetting on the skin side surface of the absorbent article can be suppressed.

[0027] Such an absorbent article, wherein the average density of the superabsorbent polymer in the non-skin side portion of the non-groove region is lower than the average density of the superabsorbent polymer in the skin side portion of the non-groove region.

[0028] According to such an absorbent article, excreted fluid that has passed through the groove region of the upper layer core and migrated to the non-skin side portion is likely to be absorbed by the non-skin side portion of the non-groove region where the density of the superabsorbent polymer is low. Therefore, the diffusibility of the excreted fluid on the non-skin side portion of the upper layer core is enhanced. In addition, the excreted fluid that has migrated to the non-skin side portion of the non-groove region is sucked up by the skin side portion of the non-groove region and retained by the superabsorbent polymer, so that rewetting of the excreted fluid on the skin side surface of the upper layer core can be suppressed.

[0029] Such an absorbent article, wherein the groove is a groove recessed from the skin side surface of the upper layer core toward the non-skin side in the thickness direction.

[0030] According to such an absorbent article, the excreted fluid excreted onto the upper layer core can be immediately dropped into and diffused in the space portion of the groove of the upper layer core. Therefore, it is possible to prevent the excreted fluid from overflowing on the skin side surface of the upper layer core.

[0031] Such an absorbent article, wherein the average density of the superabsorbent polymer in the non-skin side portion of the groove region is lower than the average density of the superabsorbent polymer in the skin side portion of the non-groove region.

[0032] According to such an absorbent article, the liquid permeability of the excreted fluid in the groove region of the upper layer core can be enhanced. Also, even when repeated excretion occurs, it is possible to suppress a decrease in the liquid permeability from the skin side portion to the non-skin side portion of the groove region due to the superabsorbent polymer that has absorbed the excreted fluid.

[0033] Such an absorbent article, wherein the upper layer core includes liquid-absorbent fibers in addition to the superabsorbent polymer, and the average density of the liquid-absorbent fibers in the non-skin side portion of the non-groove region is higher than the average density of the liquid-absorbent fibers in the non-skin side portion of the groove region.

[0034] According to such an absorbent article, excreted liquid that has passed through the groove region of the upper core and migrated to the non-skin side portion is likely to be absorbed by the non-groove region on the non-skin side portion due to capillary action. Therefore, the diffusibility of the excreted liquid in the upper core is enhanced.

[0035] Such an absorbent article, wherein the lower core comprises a superabsorbent polymer, and when the lower core is divided into two in the thickness direction, the portion located on the skin side is defined as the skin side portion, and the portion located on the non-skin side is defined as the non-skin side portion, in at least a part of the lower core, the average density of the superabsorbent polymer in the skin side portion of a certain region of the lower core is higher than the average density of the superabsorbent polymer in the non-skin side portion of the region of the upper core facing the certain region.

[0036] According to such an absorbent article, the rate of liquid migration from the upper core to the lower core can be suppressed. Therefore, the diffusibility of the excreted liquid in the upper core is enhanced, and in the lower core receiving the same, the excreted liquid is absorbed over a wide range.

[0037] Such an absorbent article, wherein the groove has a main groove having a length in the longitudinal direction which is the predetermined direction, and a sub-groove extending in the width direction from the main groove, a plurality of the main grooves are arranged at intervals in the width direction, and a plurality of the sub-grooves extend in the width direction at intervals in the longitudinal direction from the main groove.

[0038] According to such an absorbent article, in the upper core, the excreted liquid can be diffused in the longitudinal direction and also diffused in the width direction along the sub-grooves. Further, the flexibility of the upper core is enhanced, and the upper core is more likely to deform along the wearer's body.

[0039] Such an absorbent article, wherein the lower core has a superabsorbent polymer and has a second groove in which a part of the lower core is recessed in the thickness direction, the second groove has a length in the longitudinal direction, and the lower core has, when viewed in the thickness direction, a second groove region provided with the second groove and a second non-groove region not provided with the second groove, and at least a part of the second groove region is provided in a region where the upper core and the lower core overlap when viewed in the thickness direction. When the lower core is divided into two parts in the thickness direction, the part located on the skin side is defined as the skin side part, and the part located on the non-skin side is defined as the non-skin side part. The average density of the superabsorbent polymer in the skin side part of the second groove region is lower than the average density of the superabsorbent polymer in the skin side part of the second non-groove region. An absorbent article characterized by this.

[0040] According to such an absorbent article, excreted liquid that tends to stagnate at the boundary between the upper core and the lower core can be drawn into the groove region of the skin side part of the lower core. Therefore, the excreted liquid can easily migrate from the upper core to the lower core, and the absorption amount of the lower core increases.

[0041] Such an absorbent article, wherein the average density of the superabsorbent polymer in the non-skin side part of the second non-groove region is lower than the average density of the superabsorbent polymer in the skin side part of the second non-groove region. An absorbent article characterized by this.

[0042] According to such an absorbent article, excreted liquid that has passed through the groove region of the lower core and migrated to the non-skin side part is easily absorbed by the non-skin side part of the non-groove region where the density of the superabsorbent polymer is low. Therefore, the diffusibility of the excreted liquid in the non-skin side part of the lower core increases. In addition, the excreted liquid that has migrated to the non-skin side part of the non-groove region is sucked up to the skin side part of the non-groove region and retained by the superabsorbent polymer, so that rewetting of the excreted liquid can be suppressed.

[0043] Such an absorbent article, wherein the second groove is a groove that is recessed from the non-skin side surface of the lower core toward the skin side in the thickness direction. An absorbent article characterized by this.

[0044] According to such an absorbent article, the liquid permeability to the non-skin side portion (the space portion of the second groove) in the groove region of the lower layer core is increased. Therefore, the excreted liquid can be diffused along the second groove in a state where the excreted liquid is firmly drawn into the non-skin side portion of the lower layer core, and the absorption amount of the lower layer core is increased.

[0045] Such an absorbent article, characterized in that, when viewed in the thickness direction, the groove region of the upper layer core has a portion overlapping with the second groove region of the lower layer core.

[0046] According to such an absorbent article, a large amount of excreted liquid absorbed in the groove region of the upper layer core can be drawn into the groove region of the lower layer core. Therefore, it is possible to prevent the excreted liquid from overflowing on the skin side surface of the upper layer core.

[0047] Such an absorbent article, wherein the lower layer core has a slit penetrating the lower layer core in the thickness direction at the central portion in the width direction of the region where the wearer's crotch contacts, the slit has a length in the longitudinal direction, and when viewed in the thickness direction, the slit of the lower layer core overlaps with the upper layer core, and at least a part of the region of the slit of the lower layer core does not overlap with the groove region of the upper layer core.

[0048] According to such an absorbent article, by overlapping the portion of the absorbent core where the slit is provided with the non-groove region of the upper layer core, it is possible to prevent the rigidity of the absorbent core from being excessively reduced and suppress the deformation of the absorbent core.

[0049] Such an absorbent article, wherein an elastic member that expands and contracts in the longitudinal direction is disposed in the region where the wearer's crotch contacts, and when viewed in the thickness direction, all regions of the slit of the lower layer core do not overlap with the groove region of the upper layer core, and when viewed in the thickness direction, the slit has a portion overlapping with the elastic member.

[0050] According to such an absorbent article, since the slit and the groove region of the upper core do not overlap in the thickness direction, it becomes difficult for excreted liquid to transfer from the upper core to the slit, and it is possible to suppress the stagnation of excreted liquid in the slit. Further, the deformation of the absorbent core protruding toward the skin side due to the slit of the lower core is promoted by the elastic member. Therefore, the fit of the absorbent core to the crotch of the wearer is enhanced, and it becomes difficult for the slit portion of the lower core to bend and for excreted liquid to stagnate.

[0051] Such an absorbent article, wherein the groove region has a length in the longitudinal direction which is the predetermined direction, the upper core has a region in which the non-groove region is continuous from one end to the other end in the width direction on the rear side in the longitudinal direction of the slit, and in the longitudinal direction, the rear end of the lower core is located on the rear side with respect to the rear end of the upper core.

[0052] According to such an absorbent article, the absorbent core is likely to bend in the longitudinal direction along the region where the non-groove region is continuous in the width direction, and the absorbent core is likely to bend in the longitudinal direction along the rear end of the upper core. Therefore, the rear end portion of the absorbent core easily follows the buttocks of the wearer, and the fit of the absorbent core is enhanced.

[0053] Hereinafter, as an example of the absorbent article according to the present embodiment, an adult-sized pants-type diaper will be described as an example. However, the absorbent article is not limited to the above, and other absorbent articles include, for example, tape-type diapers, children's diapers, light incontinence pads, sanitary napkins, and the like.

[0054] ===Basic configuration of pants-type diaper 1=== FIG. 1 is a schematic perspective view of a pants-type diaper 1 (hereinafter also referred to as "diaper"). FIG. 2 is a schematic plan view of the diaper 1 in a deployed and stretched state as viewed from the skin side. FIG. 3 is a schematic cross-sectional view taken along line a-a of FIG. 2.

[0055] The unfolded state of the diaper 1 is a state in which the joint 2 between the front body circumferential part 21 and the rear body circumferential part 22, which will be described later, is released and unfolded. The extended state of the diaper 1 is a state in which the diaper 1 is extended without wrinkles. Specifically, it is a state in which the diaper 1 is extended until the dimensions of each material constituting the diaper 1 match or are close to the dimensions of the material alone, without being affected by the elastic member of the diaper 1.

[0056] The diaper 1 in the form of pants has an up-down direction, a width direction, and a thickness direction, and has an absorbent main body 10 and an outer member 20. In the up-down direction, the side where the body circumferential opening BH of the diaper 1 is located is defined as the upper side, and the opposite side is defined as the lower side. The longitudinal direction of the unfolded diaper 1 corresponds to the up-down direction of the diaper 1 in the form of pants and corresponds to the longitudinal direction of the absorbent main body 10. In the longitudinal direction, the side that abuts against the wearer's abdomen is defined as the front side, and the side that abuts against the wearer's buttocks is defined as the rear side. Also, in the thickness direction, the side that abuts against the wearer's skin is defined as the skin side, and the opposite side is defined as the non-skin side.

[0057] The outer member 20 is disposed on the non-skin side of the absorbent main body 10, and has a front body circumferential part 21, a rear body circumferential part 22, and a crotch part 23. The unfolded diaper 1 is folded in half at approximately the center in the longitudinal direction, and both end portions in the width direction of the front body circumferential part 21 and the rear body circumferential part 22 are joined by welding or the like, and a pair of joints 2 are formed, whereby the diaper 1 becomes a pants type.

[0058] A plurality of body circumferential elastic members 211, 221 (for example, thread rubber) along the width direction are arranged at intervals in the up-down direction (longitudinal direction) on the front body circumferential part 21 and the rear body circumferential part 22. Also, a plurality of leg circumferential elastic members 212, 222 (for example, thread rubber) are arranged along the leg circumferential opening LH on the front body circumferential part 21 and the rear body circumferential part 22. The body circumferential elastic members 211, 221 and the leg circumferential elastic members 212, 222 are fixed in an extended state between two layers of sheets (for example, non-woven fabric).

[0059] The crotch part 23 is composed of a sheet (for example, non-woven fabric) that connects the front body circumferential part 21 and the rear body circumferential part 22. However, the outer member 20 may not have the crotch part 23.

[0060] The absorbent body 10 includes an absorbent core 30 that absorbs and holds excreted liquid, a liquid-permeable surface sheet 11 (e.g., a non-woven fabric or a resin film having apertures) disposed closer to the skin side than the absorbent core 30, a liquid-permeable intermediate sheet 12 disposed between the surface sheet 11 and the absorbent core 30, a liquid-impermeable back sheet 13 (e.g., a resin film) disposed closer to the non-skin side than the absorbent core 30, a pair of side sheets 14 (e.g., a hydrophobic non-woven fabric) disposed at side portions in the width direction of the absorbent body 10, a leak-proof wall elastic member 15, a leg-around elastic member 16, a crotch elastic member 17, and a cover sheet 18 that covers the crotch elastic member 17 from the non-skin side.

[0061] Although not shown in detail, the side sheet 14 is folded back from a side portion in the width direction of the non-skin side surface of the back sheet 13 toward a side portion in the width direction of the skin side surface of the surface sheet 11. The leak-proof wall elastic member 15 and the leg-around elastic member 16 are fixed to the side sheet 14 in an extended state in the longitudinal direction. The leak-proof wall elastic member 15 is disposed at the tip of the side sheet 14 folded back inward in the width direction on the skin side surface of the surface sheet 11. The leg-around elastic member 16 is disposed at a side portion in the width direction of the absorbent body 10. The crotch elastic member 17 is disposed at the center in the longitudinal direction and the width direction of the absorbent body 10 and is fixed between the back sheet 13 and the cover sheet 18 in an extended state in the longitudinal direction.

[0062] The above is the description of the basic configuration of the pants-type diaper 1, but the configuration of the pants-type diaper 1 is not limited to the above.

[0063] ===Regarding the absorbent body 10 (absorbent core 30) === <<First Embodiment>> FIG. 4 is a plan view of the upper core 31 as seen from the skin side in the thickness direction. FIG. 5 is a plan view of the lower core 32 as seen from the skin side in the thickness direction. FIG. 6 is a plan view of the laminated upper core 31 and lower core 32 as seen from the skin side in the thickness direction. FIG. 7 is a schematic cross-sectional view of a part of the upper core 31 and lower core 32. FIG. 8A is a schematic cross-sectional view taken along line I-I of FIG. 6, and FIG. 8B is a schematic cross-sectional view taken along line II-II of FIG. 6. FIG. 9A is a schematic perspective view of the core wrap sheet 39, and FIG. 9B is an explanatory view of a modified example of the arrangement of the core wrap sheet 39. FIGS. 10A, 10B, 11A, and 11B are explanatory views of modified examples of the grooves 35 and 36.

[0064] The absorbent core 30 has a two-layer structure and includes an upper core 31 and a lower core 32 disposed on the non-skin side in the thickness direction relative to the upper core 31. The upper core 31 and the lower core 32 include liquid-absorbent fibers 33 (such as pulp fibers and cellulose-based absorbent fibers) and a superabsorbent polymer 34 (SAP).

[0065] The planar shape of each of the upper core 31 and the lower core 32 is an hourglass shape in which the central portion in the longitudinal direction is constricted inward in the width direction. As shown in FIG. 6, the lower core 32 is larger in size than the upper core 31, and the upper core 31 is arranged so as to be accommodated within the outer peripheral edge of the lower core 32.

[0066] The upper core 31 has a groove 35 in which a part of the upper core 31 is recessed in the thickness direction. In the thickness direction, there are a groove region A1 where the groove 35 is provided and a non-groove region A2 where no groove is provided. The groove 35 has a length in the longitudinal direction (predetermined direction) of the diaper 1. In the upper core 31, a plurality of grooves 35 extending in the longitudinal direction are arranged at intervals in the width direction and also at intervals in the longitudinal direction. Further, the groove 35 of the first embodiment is an upper groove that is recessed from the skin side surface of the upper core 31 toward the non-skin side in the thickness direction.

[0067] The lower core 32 also has a groove 36 (second groove) in which a part of the lower core 32 is recessed in the thickness direction. When viewed in the thickness direction, it has a groove region A3 (second groove region) where the groove 36 is provided and a non-groove region A4 (second non-groove region) where the groove 36 is not provided. However, the groove 36 of the lower core 32 is a lower groove recessed from the non-skin side surface of the lower core 32 toward the skin side in the thickness direction, contrary to the groove 35 of the upper core 31. The groove 36 has a length in the longitudinal direction of the diaper 1. In the lower core 32, a plurality of grooves 36 extending in the longitudinal direction are arranged at intervals in the width direction and also at intervals in the longitudinal direction.

[0068] Furthermore, the lower core 32 has a central slit 37 (slit) penetrating the lower core 32 in the thickness direction and a pair of side slits 38. The central slit 37 is a substantially rectangular slit that is long in the longitudinal direction and is provided at the center in the width direction of the crotch region of the diaper 1. The pair of side slits 38 are substantially rectangular slits that are long in the longitudinal direction and are located on both outer sides in the width direction of the central slit 37 and are provided at positions overlapping at least a part of the central slit 37 in the longitudinal direction. The central slit 37 is longer in both the width direction and the longitudinal direction than the side slit 38. Also, when viewed in the thickness direction, all of the central slit 37 overlaps with the upper core 31, but most of the side slit 38 does not overlap with the upper core 31.

[0069] Note that the crotch region of the diaper 1 is a region where it is assumed that the wearer's crotch contacts. Specifically, the region below (inside in the longitudinal direction) the joining portion 2 of the diaper 1 in the vertical direction is defined as the crotch region. Alternatively, the central region when the diaper 1 in the unfolded and extended state (Figure 2) is divided into three equal parts in the longitudinal direction may be defined as the crotch region.

[0070] Here, when the upper core 31 and the lower core 32 are each bisected in the thickness direction, the portions located on the skin side are defined as skin side portions 311, 321, and the portions located on the non-skin side are defined as non-skin side portions 312, 322. Specifically, they are divided into the skin side portions 311, 321 and the non-skin side portions 312, 322 with a virtual line horizontally extending from the center C in the thickness direction at the thickest part of the non-groove regions A2, A4 as the boundary.

[0071] And in the upper core 31, the average density of the superabsorbent polymer 34 in the skin-side portion 311 of the groove region A1 is lower than the average density of the superabsorbent polymer 34 in the skin-side portion 311 of the non-groove region A2. Therefore, the excreted liquid excreted onto the skin side surface of the upper core 31 is more likely to flow into the groove region A1, which is a low SAP region, than into the non-groove region A2. Thus, the excreted liquid is diffused longitudinally along the longitudinally extending groove region A1.

[0072] In particular, the groove 35 of the upper core 31 is an upper groove. Therefore, the skin-side portion 311 of the groove region A1 is the space portion of the groove 35, and the average density of the superabsorbent polymer 34 in the skin-side portion 311 of the groove region A1 is lower (zero or close to zero). Since the upper core 31 directly receives the excreted liquid, by making the groove 35 an upper groove, the excreted liquid excreted onto the skin side surface of the upper core 31 can be immediately dropped into the space portion of the groove 35 and diffused longitudinally. Thus, even when a large amount of excreted liquid is excreted, it is possible to suppress the overflow of the excreted liquid on the skin side surface of the upper core 31.

[0073] Also, if the groove 35 of the upper core 31 is a slit penetrating in the thickness direction, the excreted liquid will shift downward before diffusing along the groove region A1, and the excreted liquid will be spot-absorbed by a part of the lower core 32. There is a limit to the range in which the excreted liquid diffuses from the spot-absorbed portion, and it becomes impossible to absorb the excreted liquid in a wide range of the lower core 32. The upper core 31 also cannot absorb the excreted liquid in a wide range of the upper core 31 because the excreted liquid shifts to the lower core 32 before diffusing in the upper core 31.

[0074] In contrast, the groove 35 of the upper core 31 in the present embodiment is a groove 35 (recess) in which a part of the upper core 31 is recessed in the thickness direction. Therefore, it is possible to prevent the excreted liquid from immediately shifting from the groove region A1 to the lower core 32, and the excreted liquid can be diffused in a wide range of the upper core 31 along the groove region A1.

[0075] Also, as shown in FIG. 6, when viewed in the thickness direction, in the region where the upper core 31 and the lower core 32 overlap, a groove region A1 of a part of the upper core 31 is provided. Therefore, the lower core 32 can receive and absorb the excreted liquid diffused along the groove region A1 of the upper core 31. Thus, the diffusibility of the excreted liquid is also high in the lower core 32, and the excreted liquid is absorbed over a wide range of the lower core 32. Further, after the lower core 32 is saturated and absorbed, the excreted liquid is diffused and absorbed over a wide range of the upper core 31.

[0076] Note that the lower core 32 of the present embodiment has a central slit 37. In this case, it is preferable that the groove region A1 is provided at a part of the upper core 31 that overlaps in the thickness direction with the part of the lower core 32 where the central slit 37 is not arranged. By doing so, the lower core 32 can receive and absorb the excreted liquid diffused along the groove region A1.

[0077] Also, since the groove 35 of the upper core 31 of the present embodiment is different from a slit, the lower core 32 is not exposed on the skin side in the groove region A1. Therefore, it is possible to prevent the excreted liquid absorbed at the part of the lower core 32 facing the groove region A1 of the upper core 31 from rewetting and touching the skin. Further, the skin-side part 311 of the non-groove region A2 of the upper core 31 is a high-SAP region. Therefore, the excreted liquid absorbed by the skin-side part 311 of the non-groove region A2 is firmly held by the superabsorbent polymer 34. Thus, it is possible to suppress the rewetting of the excreted liquid on the skin side surface of the upper core 31.

[0078] As described above, in the absorbent core 30 of the present embodiment, the diffusibility of the excreted liquid in the upper core 31 and the lower core 32 is high, and the absorption amount increases. Therefore, even when excreted repeatedly, it is possible to suppress the overflow and leakage of the excreted liquid. Also, the rewetting of the excreted liquid can be suppressed.

[0079] Further, in FIG. 7, the bottom of the groove 35 in the upper core 31 is located at the boundary between the skin-side portion 311 and the non-skin-side portion 312. However, the present invention is not limited to this, and the bottom of the groove 35 may be shallower or deeper than the boundary. Also, the high SAP region of the skin-side portion 311 in the non-groove region A2 of the upper core 31 may extend to the non-skin side beyond the bottom of the groove 35 (when the groove 35 is a lower groove, the ceiling of the groove 35). Further, a part of the non-skin-side portion 312 in the groove region A1 (that is, a part of the bottom of the groove 35 or a part of the ceiling of the groove 35) may be a high SAP region. When a part of the bottom (or ceiling) of the groove 35 is a high SAP region, it becomes difficult for the excreted liquid to be drawn into the bottom (or ceiling) of the groove 35. Therefore, the excreted liquid easily diffuses over the bottom of the groove 35 (or below the ceiling), and the diffusibility of the excreted liquid in the upper core 31 is improved. The same applies to the lower core 32.

[0080] Furthermore, in the upper core 31, it is preferable that the average density of the superabsorbent polymer 34 in the non-skin-side portion 312 of the non-groove region A2 is lower than the average density of the superabsorbent polymer 34 in the skin-side portion 311 of the non-groove region A2. By doing so, the excreted liquid that has migrated downward (to the non-skin-side portion 312) from the skin-side portion 311 of the groove region A1 easily migrates to the non-skin-side portion 312 of the non-groove region A2, which is a low SAP region. Therefore, the diffusibility of the excreted liquid in the upper core 31 is enhanced. For example, when the excreted liquid flows into the non-groove region A2 arranged in the width direction parallel to the groove region A1, it diffuses in the width direction as well. Then, in order for the lower core 32 to receive the excreted liquid further diffused in the upper core 31, the excreted liquid is absorbed over a wider range of the lower core 32. However, the present invention is not limited to the above. For example, the average density of the superabsorbent polymer 34 in the non-skin-side portion 312 of the non-groove region A2 may be equal to or higher than the average density of the superabsorbent polymer 34 in the skin-side portion 311 of the non-groove region A2.

[0081] Also, the excreted liquid that has migrated to the non-skin-side portion 312 of the non-groove region A2 migrates to the lower core 32 and is also sucked up by the skin-side portion 311 of the non-groove region A2. Since the skin-side portion 311 of the non-groove region A2 is a high SAP region, the sucked-up excreted liquid is firmly held by the superabsorbent polymer 34. Therefore, it is possible to suppress the excreted liquid from rewetting on the skin side surface of the upper core 31.

[0082] Further, when the groove 35 of the upper core 31 is an upper groove, a superabsorbent polymer 34 and liquid-absorbent fibers are arranged in the non-skin side portion 312 of the groove region A1. In this case, it is preferable that the average density of the superabsorbent polymer 34 in the non-skin side portion 312 of the groove region A1 is lower than the average density of the superabsorbent polymer 34 in the skin side portion 311 of the non-groove region A2.

[0083] By doing so, the excreted liquid that has flowed into the groove region A1 (space portion) on the skin side portion 311 of the upper core 31 is likely to move to the non-skin side portion 312 (downward) of the groove region A1, which is a low SAP region. That is, the liquid permeability in the groove region A1 is increased. Therefore, even when repeated excretion is performed, it is possible to prevent the liquid permeability of the groove region A1 from being inhibited by the superabsorbent polymer 34 that has absorbed the excreted liquid.

[0084] Further, when the groove 35 of the upper core 31 is an upper groove, it is preferable that the average density of the liquid-absorbent fibers in the non-skin side portion 312 of the non-groove region A2 is higher than the average density of the liquid-absorbent fibers in the non-skin side portion 312 of the groove region A1. By doing so, the excreted liquid that has moved to the non-skin side portion 312 of the groove region A1 is likely to move to the non-skin side portion 312 of the non-groove region A2 due to capillary action. Therefore, the diffusibility of the excreted liquid in the upper core 31 is increased. And the excreted liquid is absorbed over a wider range of the lower core 32 that receives the excreted liquid diffused in the upper core 31.

[0085] Further, the upper core 31 and the lower core 32 of the present embodiment each have a thin fiber layer 313, 323 on the skin side surface. The fiber layers 313, 323 are composed of liquid-absorbent fibers 33 and do not contain superabsorbent polymers 34. The fiber layers 313, 323 facilitate the diffusion of excreted liquid in the planar direction on the skin side surfaces of the upper core 31 and the lower core 32. Therefore, the diffusibility of the excreted liquid in the upper core 31 and the lower core 32 is enhanced. However, one or both of the upper core 31 and the lower core 32 may not have the fiber layers 313, 323. Also, the thickness of the fiber layers 313, 323 is thin. Therefore, it does not affect the difference in the average density of the superabsorbent polymer 34 between the skin side portions 311, 321 (the portions including the fiber layers 313, 323) and the non-skin side portions 312, 322 (the portions not including the fiber layers 313, 323) of the upper core 31 and the lower core 32.

[0086] Also, although not shown, a thin fiber layer (a layer of liquid-absorbent fibers 33 that does not contain superabsorbent polymer 34) may be provided on the non-skin side surfaces of the upper core 31 and the lower core 32. Even in that case, on the non-skin side surfaces of the upper core 31 and the lower core 32, the excreted liquid is likely to be diffused in the planar direction, and the diffusibility of the excreted liquid in the upper core 31 and the lower core 32 is further enhanced.

[0087] Also, the comparison of the average density of the superabsorbent polymer 34 and the comparison of the average density of the liquid-absorbent fibers 33 in each part of the absorbent core 30 can be performed by well-known methods. For example, after impregnating the absorbent core 30 to be measured with liquid nitrogen and freezing it, it is cut in the thickness direction with a razor to obtain a cross-section of the absorbent core 30 including the portions to be compared (for example, the groove region A1 and the non-groove region A2). After returning the absorbent core 30 to room temperature, a cross-sectional image at a magnification of 50 times is obtained using an electron microscope (for example, Keyence VE7800, etc.). Based on the cross-sectional image, the relative high or low average density of the superabsorbent polymer 34 in the portion to be compared can be visually compared. Also, based on this cross-sectional image, the relative high or low average density of the liquid-absorbent fibers 33 in the portion to be compared can also be visually compared. Further, in the cross-sectional image, the number of superabsorbent polymers 34 and the number of liquid-absorbent fibers 33 per unit area may be counted and compared.

[0088] Further, for example, after freezing the absorbent core 30 to be measured and then cutting it, a cross-section of the absorbent core 30 including a part to be compared is obtained. A method of comparing the average density of the superabsorbent polymer 34 may be employed based on an image obtained by irradiating the cross-section with X-rays. The amount of X-ray transmission decreases in a portion where the superabsorbent polymer 34 has a large overlap. Therefore, in the X-ray image, a portion with a high average density of the superabsorbent polymer 34 is visually recognized as dark and can be compared with the light and dark of the portion to be compared. Additionally, the weight of the superabsorbent polymer 34 and the weight of the liquid-absorbent fiber 33 may be obtained by the measurement method described in Japanese Patent Application No. 2018-542962, converted into density, and compared.

[0089] As described above, by forming the absorbent core 30 into a two-layer structure, the amount of excreted fluid that the diaper 1 can absorb can be increased. However, if it is difficult for the excreted fluid to transfer from the upper core 31 to the lower core 32, there is a risk that the excreted fluid will stagnate in the space at the boundary between the upper core 31 and the lower core 32 in the thickness direction. Then, the amount of excreted fluid absorbed by the lower core 32 decreases, and the absorption performance of the lower core 32 cannot be effectively utilized.

[0090] Therefore, also in the lower core 32, it is preferable to make the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the groove region A3 lower than the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the non-groove region A4. And, when viewed in the thickness direction, at least a part of the groove region A3 of the lower core 32 may be provided in a region where the upper core 31 and the lower core 32 overlap.

[0091] By doing so, the excreted liquid that has migrated to the boundary between the upper core 31 and the lower core 32 in the thickness direction is more likely to be absorbed by the groove region A3, which is a low-SAP region, in the skin-side portion 321 of the lower core 32. Therefore, it is possible to suppress the stagnation of the excreted liquid at the boundary between the upper core 31 and the lower core 32, and the excreted liquid can be transferred to the lower core 32. Thus, the lower core 32 can firmly absorb the excreted liquid, and it is possible to prevent the amount of excreted liquid that the diaper 1 can absorb from decreasing. On the other hand, the skin-side portion 321 of the non-groove region A4 of the lower core 32 is a high-SAP region. Therefore, the excreted liquid absorbed by the skin-side portion 321 of the non-groove region A4 is firmly held by the superabsorbent polymer 34, and rewetting of the excreted liquid can be suppressed.

[0092] In addition, the excreted liquid absorbed by the groove region A3 is likely to migrate to the lower space portion (non-skin side portion 322). Thereafter, the excreted liquid is diffused in the longitudinal direction along the space portion of the groove region A3. Therefore, the excreted liquid diffused in the upper core 31 is further diffused in the lower core 32, and the excreted liquid is absorbed in a wider range of the lower core 32.

[0093] In addition, the groove 36 of the lower core 32 is a groove 36 (recess) in which a part of the lower core 32 is recessed in the thickness direction. Therefore, unlike the case where the groove 36 is a slit penetrating in the thickness direction, it is possible to suppress the stagnation of the excreted liquid in the groove 36. That is, the excreted liquid can also be diffused in the portion where the liquid-absorbent fiber 33 and the superabsorbent polymer 34 are arranged.

[0094] In addition, when the groove 36 of the lower core 32 is a lower groove, the liquid permeability to the lower part (space portion) in the groove region A3 is high. Therefore, after the excreted liquid is drawn into the non-skin side portion 322 of the lower core 32, it can be diffused, and the lower core 32 can be effectively utilized. Further, the groove 36 of the lower core 32 is not a slit but a lower groove, and since there is no space portion (recess) of the groove 36 on the skin side surface of the lower core 32, the transfer rate of the excreted liquid from the upper core 31 to the lower core 32 can be appropriately suppressed. Therefore, the excreted liquid is diffused in the upper core 31 before migrating to the lower core 32.

[0095] Similarly, as with the upper core 31, in the lower core 32 as well, it is preferable that the average density of the superabsorbent polymer 34 in the non-skin side portion 322 of the non-groove region A4 is lower than the average density of the superabsorbent polymer 34 in the skin side portion 321 of the non-groove region A4.

[0096] By doing so, in the non-skin side portion 322 of the lower core 32, the excreted liquid diffused longitudinally along the space portion of the groove 36 is likely to migrate to the non-skin side portion 322 of the non-groove region A4 which is a low SAP region. Therefore, the diffusibility of the excreted liquid in the lower core 32 is further enhanced. Also, the excreted liquid that has migrated to the non-skin side portion 322 of the non-groove region A4 is sucked up by the skin side portion 321 of the non-groove region A4. Since the skin side portion 321 of the non-groove region A4 is a high SAP region, the sucked-up excreted liquid is firmly held, and rewetting of the excreted liquid can be suppressed.

[0097] Also, the planar shape of the lower core 32 is slightly larger than the planar shape of the upper core 31, and the lower core 32 extends outward in the longitudinal direction beyond the longitudinal end 31a of the upper core 31. At the portion of the lower core 32 that extends outward in the longitudinal direction beyond the upper core 31, although the excreted liquid does not stagnate at the boundary with the upper core 31, it is preferable to provide the groove region A3 of the lower core 32 also at that portion.

[0098] By doing so, the excreted liquid can be diffused to the region of the lower core 32 that does not overlap with the upper core 31 when viewed in the thickness direction. Also, the longitudinal ends of the lower core 32 are provided with grooves 36, so that flexibility is obtained and they are easily deformed. Therefore, the lower core 32 can be more easily fitted to the lower abdomen and buttocks of the wearer.

[0099] Also, when viewed in the thickness direction, it is preferable that the groove region A1 of the upper core 31 has a portion that overlaps with the groove region A3 of the lower core 32. In the first embodiment, most of the grooves 35 of the upper core 31 (other than the two grooves 35A that overlap with the central slit 37) overlap with the grooves 36 of the lower core 32.

[0100] In the upper core 31, the amount of excreted fluid flowing downward (non-skin side) through the groove region A1 is larger than that through the non-groove region A2. Therefore, if the positions of the groove region A1 of the upper core 31 and the groove region A3 of the lower core 32 are aligned, a large amount of excreted fluid flowing through the groove region A1 of the upper core 31 can be received by the groove region A3 of the lower core 32 and drawn into and diffused in the interior of the lower core 32 (the space portion of the non-skin side portion 322). Thus, stagnation of the excreted fluid at the boundary between the upper core 31 and the lower core 32 can be further suppressed. In the present embodiment, the groove 35 of the upper core 31 and the groove 36 of the lower core 32 that overlaps it have the same shape and the same arrangement position, but the present invention is not limited thereto, and it is sufficient that at least a part thereof overlaps.

[0101] Also, in at least a part of the lower core 32, it is preferable that the average density of the superabsorbent polymer 34 in the skin side portion 321 of a certain region of the lower core 32 is higher than the average density of the superabsorbent polymer 34 in the non-skin side portion 311 of the region of the upper core 31 facing the certain region. By doing so, the transfer rate of the excreted fluid from the upper core 31 to the lower core 32 can be appropriately suppressed. Thus, the excreted fluid is diffused in the upper core 31 before migrating to the lower core 32.

[0102] Specifically, in the absorbent core 30 of the first embodiment, most of the groove region A1 of the upper core 31 overlaps with the groove region A3 of the lower core 32, and most of the non-groove region A2 of the upper core 31 overlaps with the non-groove region A4 of the lower core 32. As described above, the non-groove region A4 of the skin side portion 321 of the lower core 32 is a high SAP region, and the non-groove region A2 of the non-skin side portion 312 of the upper core 31 facing it is a low SAP region, and the above relationship is established. On the other hand, both the groove region A3 of the skin side portion 321 of the lower core 32 and the groove region A1 of the non-skin side portion 312 of the upper core 31 facing it are low SAP regions. Therefore, it is preferable to increase the average density of the superabsorbent polymer 34 in the groove region A3 of the skin side portion 321 of the lower core 32 compared to the groove region A1 of the non-skin side portion 312 of the upper core 31.

[0103] Further, the lower core 32 has a central slit 37 extending in the longitudinal direction at the central portion in the width direction of the region where the wearer's crotch contacts. Therefore, the lower core 32 and the upper core 31 overlapping therewith are bent along the central slit 37 (along the longitudinal direction). Thus, the central portion in the width direction of the absorbent core 30 is deformed to be convex toward the skin side with respect to the side portions, making it easier to fit the wearer's crotch.

[0104] Furthermore, when viewed in the thickness direction, the groove region A1 of the upper core 31 has a portion (groove 35A in FIG. 6) overlapping with the central slit 37. In the portion of the absorbent core 30 where the central slit 37 is disposed, the absorption ability of excreted liquid decreases, but the excreted liquid can be diffused in the groove region A1 of the upper core 31 overlapping with the central slit 37. In particular, it is preferable that the longitudinal ends of the groove region A1 of the upper core 31 extend outward in the longitudinal direction from the central slit 37. By doing so, the excreted liquid can be transferred to the portion that does not overlap with the central slit 37. Thus, the overflow of excreted liquid in the crotch region can be suppressed.

[0105] However, it is not limited to the above. The portion of the absorbent core 30 where the central slit 37 is disposed has low rigidity. Therefore, when viewed in the thickness direction, at least a part of the region of the central slit 37 of the lower core 32 may not overlap with the groove region A1 (groove 35) of the upper core 31. For example, as shown in the modified example of FIG. 10A, all regions of the central slit 37 may not overlap with the groove region A1 of the upper core 31. By doing so, it is possible to prevent the portion of the absorbent core 30 with low rigidity due to the central slit 37 from becoming even lower in rigidity due to the groove region A1, and suppress the deformation of the absorbent core 30. Thus, the absorption performance of the absorbent core 30 can be exhibited over a long period of time. Also, a liquid pool of excreted liquid is likely to occur in the central slit 37. Therefore, by making the region of the upper core 31 overlapping with the central slit 37 into the non-groove region A2, the skin side portion 311 becomes a high SAP region, and the transfer of excreted liquid to the central slit 37 can be suppressed. Thus, the liquid pool in the central slit 37 can be suppressed.

[0106] Further, it is preferable that the groove 35 of the upper core 31 does not extend to the outer peripheral edge of the upper core 31, and the groove 36 of the lower core 32 also does not extend to the outer peripheral edge of the lower core 32. By doing so, it is possible to suppress the collapse of the upper core 31 and the lower core 32. Further, it is possible to suppress the diffusion of the excreted liquid to the outer peripheral edges of the upper core 31 and the lower core 32.

[0107] Further, as described above, in the diaper 1, in the region where the wearer's crotch contacts, a crotch elastic member 17 that expands and contracts in the longitudinal direction is disposed. As shown in FIG. 6, in the thickness direction, it is preferable that the central slit 37 and the groove region A1 of the upper core 31 each have a portion overlapping with the crotch elastic member 17.

[0108] By doing so, the deformation in which the absorbent core 30 bulges toward the skin side due to the central slit 37 is promoted by the expansion and contraction of the crotch elastic member 17. Further, the absorbent core 30 becomes flexible due to the groove region A1 and is easily deformed to fit the wearer's crotch. This deformation is also promoted by the expansion and contraction of the crotch elastic member 17. Therefore, the fitness of the diaper 1 to the wearer is increased.

[0109] Further, as shown in the modification example of FIG. 10A, even when all regions of the central slit 37 of the lower core 32 do not overlap with the groove region A1 of the upper core 31, in the thickness direction, it is preferable that the central slit 37 has a portion overlapping with the crotch elastic member 17. By doing so, the deformation in which the absorbent core 30 bulges toward the skin side due to the central slit 37 is promoted by the crotch elastic member 17, and the portion of the central slit 37 of the lower core 31 is less likely to bend and the excreted liquid is less likely to stagnate.

[0110] Further, in the longitudinal direction, at the site overlapping the central slit 37 of the lower core 32, the side ends in the width direction of the upper core 31 are located outside the central slit 37 in the width direction and inside the side ends in the width direction of the lower core 32 in the width direction. Therefore, the side portions in the width direction of the lower core 32 are easily bent along the side ends in the width direction of the upper core 31 (along the longitudinal direction). That is, the side portions in the width direction of the lower core 32 are easily raised toward the skin side.

[0111] Further, the lower core 32 has a pair of side slits 38 on both sides in the width direction of the central slit 37. The positions of the side slits 38 in the width direction are substantially the same as the positions of the side ends in the width direction of the upper core 31. Therefore, the side portions of the lower core 32 in the width direction are also likely to rise on the skin side due to the pair of side slits 38. Thus, in the crutch region, the central portion in the width direction of the absorbent core 30 is likely to deform convexly on the skin side, the side portions in the width direction rise on the skin side, and the cross section is likely to deform into a W shape. Therefore, it becomes easier to fit the wearer's crutch area.

[0112] And, it is preferable that at least one of the groove 35 of the upper core 31 and the groove 36 of the lower core 32 is provided in a region where the upper core 31 and the lower core 32 overlap outside the central slit 37 of the lower core 32 in the width direction. By doing so, a highly rigid region where the two cores 31 and 32 overlap is provided with flexibility by the grooves 35 and 36 and is likely to deform, making it easier to fit the wearer's crutch area.

[0113] Also, it is preferable that a groove region A3 (groove 36A) of the lower core 32 is provided at a position outside the side slit 38 of the lower core 32 in the width direction and overlapping at least a part of the side slit 38 in the longitudinal direction. By doing so, the flexibility of the side portion in the width direction of the lower core 32 that has risen on the skin side is increased. Therefore, the side portion in the width direction of the lower core 32 is likely to deform along the root of the wearer's leg, increasing the fit.

[0114] However, it is not limited to the above, and the lower core 31 may have a configuration without one or both of the central slit 37 and the side slit 38.

[0115] Also, the groove 36 of the lower core 32 is preferably arranged apart from the outer peripheral edges of the central slit 37 and the side slit 38. By doing so, the collapse of the shape of the lower core 32 can be suppressed.

[0116] Note that the widths (lengths in the width direction) of the central slit 37 and the side slits 38 are preferably larger than the widths of the grooves 35 in the upper core 31 and the grooves 36 in the lower core 32 (the lengths in the width direction of the main grooves 351 and 361, and the lengths in the longitudinal direction of the sub-grooves 352 and 362). By doing so, the absorbent core 30 is more likely to be deformed into a W shape by the central slit 37 and the side slits 38. On the other hand, by not making the widths of the grooves 35 and 36 too large, the absorbent core 30 can be prevented from losing its shape. The widths of the central slit 37 and the side slits 38 are preferably about 7 mm to 50 mm, for example, so that the absorption performance does not decrease too much. The widths of the grooves 35 and 36 are preferably about 1 mm to 8 mm, for example. Further, the longitudinal lengths of the central slit 37 and the side slits 38 are preferably the lengths that contact the crotch portion of the wearer, for example, about 50 to 300 mm, preferably about 100 to 250 mm.

[0117] In addition, the grooves 35 in the upper core 31 and the grooves 36 in the lower core 32 each have main grooves 351 and 361 having lengths in the longitudinal direction, and sub-grooves 352 and 362 extending in the width direction from the main grooves 351 and 361. Specifically, a plurality of sub-grooves 352 and 362 extend in the width direction at intervals in the longitudinal direction from the main grooves 351 and 361. A plurality of such main grooves 351 and 361 are arranged at intervals in the width direction and the longitudinal direction.

[0118] The sub-grooves 352 and 362 allow the excreted liquid excreted on the skin side surface of the upper core 31 and the excreted liquid drawn into the non-skin side portion 322 (space portion) of the lower core 32 to diffuse not only in the longitudinal direction but also in the width direction. Therefore, the diffusibility of the excreted liquid in the upper core 31 and the lower core 32 can be further enhanced.

[0119] In addition, by forming the absorbent core 30 into a two-layer structure, while the absorption amount of the excreted liquid increases, the absorbent core 30 becomes more rigid and difficult to deform. However, the upper core 31 and the lower core 32 of the present embodiment have grooves 35 and 36. In particular, the grooves 35 and 36 are provided in the region where the upper core 31 and the lower core 32 overlap and the rigidity increases. Therefore, the absorbent core 30 is provided with flexibility and is easily deformed along the body of the wearer.

[0120] Further, the grooves 35 and 36 have not only main grooves 351 and 361 along the longitudinal direction but also sub-grooves 352 and 362 along the width direction. Therefore, the upper core 31 and the lower core 32 are not only easily bent along the longitudinal direction but also easily bent along the width direction starting from the sub-grooves 352 and 362. Therefore, the absorbent core 30 is easily curved in the longitudinal direction along the portion extending from the lower abdomen to the buttocks of the wearer.

[0121] Also, in the first embodiment, most of the grooves 35 of the upper core 31 overlap with the grooves 36 of the lower core 32. Further, not only do the main grooves 351 of the upper core 31 and the main grooves 361 of the lower core 32 overlap, but the sub-grooves 352 of the upper core 31 and the sub-grooves 362 of the lower core 32 also overlap. Therefore, the overlapping region of the upper core 31 and the lower core 32 is even more easily bent in the longitudinal direction and the width direction along the grooves 35 and 36 and is easily deformed along the body of the wearer.

[0122] Also, the longitudinal positions of the adjacent sub-grooves 352 and 362 in the width direction are aligned. Therefore, the upper core 31 and the lower core 32 are easily bent along the width direction starting from the sub-grooves 352 and 362 and are easily deformed along the body of the wearer.

[0123] Also, as shown in FIG. 6, the upper core 31 and the lower core 32 have regions A21, A41, and A42 in which non-groove regions A2 and A4 are continuous from one end to the other end in the width direction on the rear side in the longitudinal direction with respect to the central slit 37. In this way, by providing the regions A21, A41, and A42 where the grooves 35 and 36 are not continuously arranged in the width direction at the rear ends of the upper core 31 and the lower core 32, the upper core 31 and the lower core 32 are easily bent in the longitudinal direction along that region (starting from the longitudinal ends of the grooves 35 and 36). In other words, it becomes difficult for the longitudinal folding of the upper core 31 and the lower core 32 to be inhibited by the longitudinally extending grooves 35 and 36. Therefore, the rear ends of the upper core 31 and the lower core 32 are easily along the rounded buttocks of the wearer.

[0124] Furthermore, as shown in FIG. 6, the rear end 32a of the lower core 32 is located behind the rear end 31a of the upper core 31, and the rear end 31a of the upper core 31 is located in the non-groove region A42 continuous in the width direction of the lower core 32. Therefore, the rear end portion of the lower core 32 is likely to bend in the longitudinal direction along the rear end 32a of the upper core 31. Thus, the rear end portion of the lower core 32 is likely to follow the rounded buttocks of the wearer.

[0125] Also, as described above, since the rear end portion of the absorbent core 30 is likely to bend in the longitudinal direction, it is possible to prevent the W-shaped deformation (deformation due to the central slit 37 and the side slit 38) in the crotch region of the absorbent core 30 from being transmitted to the rear of the absorbent core 30. Thus, the rear end portion of the absorbent core 30 is likely to follow the buttocks of the wearer.

[0126] Also, when viewed in the thickness direction, the region where the upper core 31 and the lower core 32 do not overlap (the region of only the lower core 32) has low rigidity and high flexibility. Therefore, although not shown, in the region of only the lower core 32, the width of the groove 36 of the lower core 32 (specifically, the length in the width direction of the main groove 361 and the length in the longitudinal direction of the sub-groove 362) may be made narrower than in the region where the upper core 31 and the lower core 32 overlap. By doing so, the collapse of the shape of the lower core 32 can be suppressed.

[0127] Also, when viewed in the thickness direction, the boundary portion (the outer peripheral edge portion of the upper core 31) between the region where the upper core 31 and the lower core 32 overlap and the region where they do not overlap is likely to be the starting point of folding of the absorbent core 30, while also being likely to be the starting point of the collapse of the shape of the absorbent core 30. Therefore, it is preferable not to provide the groove regions A1 and A3 at the boundary portion, and particularly preferably not to provide the groove region A3 of the lower core 32. By doing so, the collapse of the shape of the absorbent core 30 can be suppressed.

[0128] As shown in FIGS. 8A and 8B, a core wrap sheet 39, which is a liquid-permeable sheet (such as a tissue or a non-woven fabric), may be provided at the boundary between the upper core 31 and the lower core 32. As the core wrap sheet 39, as shown in FIG. 9A, a non-woven fabric with concavo-convex processing having convex portions 391 and concave portions 392 extending in the longitudinal direction can be exemplified. Due to the concavo-convex of the core wrap sheet 39, the excreted liquid can be diffused in the longitudinal direction, and the diffusibility of the excreted liquid in the upper core 31 and the lower core 32 is improved. Note that the concavo-convex of the core wrap sheet 39 is not limited to extending in the longitudinal direction, and may extend in the width direction or other directions. Also, due to the concavo-convex of the core wrap sheet 39, the storage space for the excreted liquid increases. Therefore, even when a large amount of excreted liquid is excreted, the excreted liquid can be temporarily stored in the storage space of the core wrap sheet 39, so that it is possible to prevent the excreted liquid from overflowing on the skin side surface of the upper core 31. Also, although not shown, in the core wrap sheet 39, the convex portions 391 and the concave portions 392 extending in the longitudinal direction may be intermittently arranged in the longitudinal direction. In that case, the excreted liquid can be diffused in the width direction at the intermittent portions of the concavo-convex.

[0129] Further, by disposing the above-described core wrap sheet 39 at the boundary between the upper core 31 and the lower core 32 (by opposing the concavo-convex surface of the core wrap sheet 39 to the non-skin side surface of the upper core 31), the excreted liquid can be further diffused on the non-skin side surface of the upper core 31. However, the core wrap sheet 39 shall not be limited to a sheet having concavo-convex.

[0130] Also, the core wrap sheet 39 is not limited to being disposed only at the boundary between the upper core 31 and the lower core 32. For example, as shown in FIG. 9B, the core wrap sheet 39 may be disposed so as to be wound from the non-skin side surface to the skin side surface of the lower core 32. By doing so, the core wrap sheet 39 can suppress the deformation of the lower core 32. Further, the core wrap sheet 39 may be disposed at a portion other than the boundary between the upper core 31 and the lower core 32 (for example, a portion of the lower core 32 excluding the portions p1 to p2 in FIG. 9B). By doing so, at the boundary between the upper core 31 and the lower core 32, the adhesive for adhering the core wrap sheet 39 and the absorbent core 30 can be eliminated, and the liquid permeability from the upper core 31 to the lower core 32 can be improved. Also, the core wrap sheet 39 may be disposed so as to be wound from the skin side surface to the non-skin side surface of the lower core 32 in the direction opposite to FIG. 9B. In that case, when trying to completely wind the lower core 32, the core wrap sheet 39 overlaps, but since the overlap region is disposed on the non-skin side surface of the lower core 32, compared to the case where it is disposed between the upper core 31 and the lower core 32, the liquid transfer from the upper core 31 to the lower core 32 becomes smoother, and the accumulation of excreted liquid can be suppressed. In addition, the core wrap sheet 39 may be disposed on a part or around the upper core 31, or the core wrap sheet 39 may not be disposed on the absorbent core 30.

[0131] Also, the shapes, numbers, and arrangement positions of the grooves 35 in the upper core 31 and the grooves 36 in the lower core 32 are not limited to those illustrated in FIGS. 4 to 6. For example, in the absorbent core 30 of FIG. 10B, the grooves 35B and 36B provided at the side portions in the width direction at the front end portion of the upper core 31 are inclined inward in the width direction toward the center side in the longitudinal direction. Therefore, the front end portion of the absorbent core 30 rising from the most constricted portion of the lower core 32 is easily deformed into an inverted triangular cup shape so as to wrap around the lower abdomen of the wearer, and the fit of the diaper 1 is improved.

[0132] Further, for example, as shown in FIG. 11A, at the central portion of the absorbent core 30 in the longitudinal direction, the sub-grooves 352 and 362 extend from the main grooves 351 and 361, but at the end portions of the absorbent core 30 in the longitudinal direction, the sub-grooves 352 and 362 are not provided. Also, the longitudinal end portions of the lower layer core 32 are non-groove regions A4. In this way, the area ratios of the groove regions A1 and A3 may be made smaller at the longitudinal end portions of the upper layer core 31 and the lower layer core 32 than at the central portion. By doing so, the collapse of the absorbent core 30 can be suppressed.

[0133] Further, for example, as shown in FIG. 11B, the grooves 35 and 36 may extend long to both longitudinal ends of the upper layer core 31 and the lower layer core 32. By doing so, the excreted liquid can be diffused longitudinally for a long distance. In that case, non-groove regions A22 and A43 that are continuous in the width direction may be provided behind the central slit 37 so that the rear end portion of the absorbent core 30 follows the wearer's buttocks (FIG. 11B), or although not shown, the grooves 35 and 36 may continuously extend from the front end to the rear end in the longitudinal direction of the upper layer core 31 and the lower layer core 32.

[0134] In addition, the groove 35 of the upper layer core 31 and the groove 36 of the lower layer core 32 are not limited to having a predetermined length in the longitudinal direction, and may be grooves extending in another direction such as the width direction, for example. Also, the groove 35 of the upper layer core 31 and the groove 36 of the lower layer core 32 may be grooves extending in different directions. Also, when viewed in the thickness direction, the groove 35 of the upper layer core 31 and the groove 36 of the lower layer core 32 may not overlap at all. Also, the groove 35 of the upper layer core 31 and the groove 36 of the lower layer core 32 may not have the sub-grooves 352 and 362. Also, the groove regions A1 and A3 may not be provided in the region where the upper layer core 31 and the lower layer core 32 do not overlap when viewed in the thickness direction.

[0135] <<Second Embodiment>> FIG. 12 is a schematic cross-sectional view of the absorbent core 30 in the second embodiment. The upper core 31 of the second embodiment is the same as the upper core 31 of the first embodiment. Further, the lower core 32 of the second embodiment has a groove 36 (lower groove) that is recessed from the non-skin side to the skin side, similar to the lower core 32 of the first embodiment. However, in the second embodiment, the superabsorbent polymer 34 is evenly disposed throughout the lower core 32 (in the portion excluding the fiber layers 313 and 323). That is, the difference in the average density of the superabsorbent polymer 34 in each part of the lower core 32 is equivalent, and is smaller than the difference in the average density of the superabsorbent polymer 34 in each part of the upper core 31 (for example, the groove region A1 and the non-groove region A2 of the skin-side portion 311).

[0136] Also in this case, the excreted liquid diffused by the upper core 31 can be received by the lower core 32, and the excreted liquid is absorbed over a wide range of the lower core 32. Further, when the fiber layer 323 is provided on the skin-side surface of the lower core 32, the excreted liquid can be further diffused in the planar direction on the skin-side surface of the lower core 32. And since the superabsorbent polymer 34 is evenly disposed in the groove region A3 and the non-groove region A4 of the skin-side portion 321, the diffused excreted liquid can directly migrate to the non-skin side portion 322. The excreted liquid that has migrated to the non-skin side portion 322 is diffused in the longitudinal direction in the space portion of the groove 36 of the lower core 32, and the excreted liquid is absorbed over a wide range of the lower core 32. Also, in the case of the lower core 32 of the second embodiment, since there is no high SAP region in the skin-side portion 321, it is possible to prevent the liquid permeability from being inhibited by the superabsorbent polymer 34 that has absorbed the excreted liquid even when repeated excretion is performed.

[0137] Also, although not shown, in the lower core 32 in which the superabsorbent polymer 34 is evenly disposed, the groove 36 of the lower core 32 may be an upper groove (a groove recessed from the skin side to the non-skin side). Also in this case, the excreted liquid received from the upper core 31 can be diffused in the space portion of the groove 36 of the lower core 32.

[0138] <<Third Embodiment>> FIG. 13 is a schematic cross-sectional view of the absorbent core 30 in the third embodiment. The upper core 31 of the third embodiment is the same as the upper core 31 of the first embodiment. Also, the lower core 32 of the third embodiment does not have the groove 36, and the superabsorbent polymer 34 is evenly disposed throughout the lower core 32 (in the portion excluding the fiber layers 313 and 323). The lower core 32 is provided with a central slit 37 and the like, and is more likely to collapse in shape compared to the upper core 31. However, since the groove 36 is not provided in the lower core 32 of the third embodiment, the lower core 32 is less likely to collapse in shape.

[0139] Also in this case, the excreted liquid diffused by the upper core 31 can be received by the lower core 32, and the excreted liquid is absorbed over a wide range of the lower core 32. Further, when the fiber layer 323 is provided on the skin side surface of the lower core 32, the excreted liquid can be further diffused in the planar direction on the skin side surface of the lower core 32. And since the superabsorbent polymer 34 is evenly disposed in the skin side portion 321, the diffused excreted liquid can directly migrate to the non-skin side portion 322. Also, in the case of the lower core 32 of the third embodiment, since there is no high SAP region in the skin side portion 321, it is possible to prevent the liquid permeability from being inhibited by the superabsorbent polymer 34 that has absorbed the excreted liquid even when repeated excretion is performed.

[0140] <<Fourth Embodiment>> FIGS. 14A and 14B are schematic cross-sectional views of the absorbent core 30 in the fourth embodiment. The groove 35 of the upper core 31 in the fourth embodiment is a lower groove, contrary to the upper core 31 of the first embodiment. Also in this case, in the skin side portion 311 of the upper core 31, the average density of the superabsorbent polymer 34 is made lower in the groove region A1 than in the non-groove region A2. By doing so, the excreted liquid excreted into the upper core 31 is more likely to be absorbed by the groove region A1 which is a low SAP region. Then, the excreted liquid that has migrated to the non-skin side portion 312 (the space portion of the groove 35) of the groove region A1 is diffused in the longitudinal direction. The lower core 32 receives the excreted liquid diffused by the upper core 31, and the excreted liquid is absorbed over a wide range of the lower core 32.

[0141] Even when the groove 35 of the upper core 31 is a lower groove, the groove 36 of the lower core 32 may be a lower groove (FIG. 14A) or an upper groove (FIG. 14B), and may also be the lower core 32 described in the second embodiment or the third embodiment.

[0142] Also, as shown in FIG. 14B, by aligning the positions of the groove 35 (lower groove) of the upper core 31 and the groove 36 (upper groove) of the lower core 32, the space capable of temporarily storing the excreted liquid that has passed through the skin side portion 311 of the upper core 31 becomes larger, and the stored excreted liquid can diffuse along the grooves 35 and 36. Therefore, even when a large amount of excreted liquid is excreted, it is possible to suppress the excreted liquid from overflowing on the skin side surface of the upper core 31.

[0143] When the groove 35 of the upper core 31 is a lower groove, the upper core 31 is more likely to be deformed so that the central portion in the width direction protrudes toward the skin side with respect to the side portions. Therefore, the deformation due to the central slit 37 of the lower core 32 is promoted, and the absorbent core 30 is more likely to fit the crotch portion of the wearer. Conversely, when the groove 36 of the lower core 32 is an upper groove, the lower core 32 is more likely to be deformed so that the central portion in the width direction protrudes toward the non-skin side compared to the side portions. Therefore, it is more likely to be deformed along the rounded buttocks.

[0144] <<Fifth Embodiment>> FIG. 15 is a schematic plan view of the diaper 1 of the fifth embodiment in a deployed and extended state as viewed from the skin side. FIG. 16 is a schematic cross-sectional view taken along line A-A in FIG. 15. FIG. 17 is a plan view of the laminated upper core 31 and lower core 32 as viewed from the skin side in the thickness direction. FIG. 18A is a plan view of the upper core 31 as viewed from the skin side in the thickness direction. FIG. 18B is a plan view of the lower core 32 as viewed from the skin side in the thickness direction. FIG. 19 is a plan view of the absorbent core 30 of a modified example of the fifth embodiment as viewed from the skin side in the thickness direction.

[0145] The upper core 31 of the fifth embodiment has a groove 35 (upper groove) that is recessed from the skin side surface of the upper core 31 toward the non-skin side in the thickness direction, as shown in FIG. 16. The lower core 32 has a central slit 37 and a pair of side slits 38, as shown in FIG. 18B, but does not have a groove in which a part of the lower core 31 is recessed.

[0146] As shown in FIG. 17, the absorbent core 30 has a "central portion in the width direction" and a pair of "side portions in the width direction" which are partitioned by dividing its maximum width into three equal parts in the width direction. Further, the absorbent core 30 has a "front side portion 30F" located on the front side in the longitudinal direction with respect to the product center line CL, and a "rear side portion 30B" located on the rear side in the longitudinal direction with respect to the product center line CL.

[0147] The product center line CL (center line) is a line that bisects (divides into two equal parts) the diaper 1 (FIG. 15) in the unfolded and stretched state in the longitudinal direction. Further, the longitudinal center of the absorbent core 30 is not limited to coinciding with the product center line CL, and may be offset. That is, the absorbent core 30 may be disposed offset to the front side or the rear side of the diaper 1. In that case, the longitudinal lengths of the front side portion 30F and the rear side portion 30B are different.

[0148] And, the rear side portion 30B of the absorbent core 30 has a region obtained by dividing its maximum length (the length from the product center line CL to the rearmost end of the absorbent core 30) into three equal parts in the longitudinal direction. The central region at that time is referred to as the "rear side first region 30B1", the region on the front side of the rear side first region 30B1 is referred to as the "rear side second region 30B2", and the region on the rear side of the rear side first region 30B1 is referred to as the "rear side third region 30B3".

[0149] Similarly, the front side portion 30F of the absorbent core 30 has a region obtained by dividing its maximum length (the length from the product center line CL to the foremost end of the absorbent core 30) into three equal parts in the longitudinal direction. The central region at that time is referred to as the "front side first region 30F1", the region on the rear side of the front side first region 30F1 is referred to as the "front side second region 30F2", and the region on the front side of the front side first region 30F1 is referred to as the "front side third region 30F3".

[0150] That is, in the following description, a rectangular region defined by the maximum width and the maximum length of the absorbent core 10 is partitioned into a region on the front side and a region on the rear side in the longitudinal direction with the product center line CL as a boundary. The absorbent core 30 is also partitioned in accordance with the regions obtained by dividing the region on the front side and the region on the rear side into nine equal parts respectively.

[0151] In the fifth embodiment, although the pants-type diaper 1 is taken as an example of the absorbent article, the absorbent article of the fifth embodiment is also applicable to other absorbent articles such as tape-type diapers and absorbent pads. Even when applied to a tape-type diaper or an absorbent pad, the product center line is specified in a state where they are unfolded in the longitudinal direction, and the absorbent core is partitioned as shown in FIG. 17.

[0152] As described in the first embodiment, the skin-side portion of the groove region A1 of the upper core 31 has a lower average density of the superabsorbent polymer 34 than the skin-side portion of the non-groove region A2. Therefore, the excreted liquid excreted from the wearer easily flows into the groove region A1, and then is easily absorbed into the absorbent core 31 while diffusing along the groove region A1. By doing so, it is possible to prevent the excreted liquid from overflowing from the surface of the diaper 1 and leaking to the outside without being absorbed by the absorbent core 31. Further, by diffusing the excreted liquid, the upper core 31 can be effectively utilized over a wide range in the planar direction.

[0153] In particular, when the groove 35 of the upper core 31 is an upper groove, the excreted liquid can be immediately dropped into the space portion of the groove 35, so that leakage (overflow) of the excreted liquid can be further suppressed. However, it may be a lower groove like the groove 35 of the upper core 31 in the fourth embodiment. Also in this case, the excreted liquid is easily absorbed into the absorbent core 30 from the skin-side portion of the groove region A1 which is a low SAP region, and leakage of the excreted liquid can be suppressed.

[0154] Furthermore, similar to the absorbent core 30 shown in FIG. 7 of the first embodiment, the groove 35 of the upper core 31 is not a groove compressed in the thickness direction. In the groove region A1, the basis weight (g / m 2 ) of the upper core 31 (liquid-absorbing fiber 33 and superabsorbent polymer 34) is preferably lower than that of the non-groove region A2. By doing so, the excreted liquid more easily flows into the groove region A1 and is more easily absorbed into the absorbent core 31 from the groove region A1, and leakage of the excreted liquid can be suppressed.

[0155] Incidentally, the basis weight (g / m 2) The comparison can be confirmed by a well-known method. For example, after impregnating the upper core 31 with liquid nitrogen and freezing it, cut it in the thickness direction with a razor to obtain a cross-section of the upper core 31 including the parts to be compared (the groove region A1 and the non-groove region A2). After returning the upper core 31 to room temperature, observe the cross-sectional image using an electron microscope, and visually compare the amount of material in the groove region A1 and the non-groove region A2, or count the number of materials for comparison.

[0156] Also, as a method for manufacturing the upper core 31 (absorbent core 30) with a lower basis weight in the groove region A1 than in the non-groove region A2, for example, it can be manufactured by laminating the material of the upper core 31 on a pattern plate provided with protrusions corresponding to the groove region A1 on the bottom surface. Further, by controlling the amount of the material (liquid absorbent fiber 33 and superabsorbent polymer 34) supplied toward the pattern plate, etc., the basis weight and average density of the material can be controlled.

[0157] As described above, due to the groove region A1 of the upper core 31, excreted liquid is easily absorbed inside the absorbent core 30. However, in the groove region A1, the thickness of the upper core 31 is thin, and the density of the superabsorbent polymer 34 in the skin side portion 311 is low, or the basis weight of the entire groove region A1 is low, so rewetting of excreted liquid is likely to occur.

[0158] Therefore, in the absorbent core 30 of the fifth embodiment, the value obtained by dividing the area of the groove region A1 of the upper core 31 located at the center in the width direction of the rear first region 30B1 by the area of the center in the width direction of the rear first region 30B1 is smaller than the value obtained by dividing the area of the groove region A1 of the upper core 31 located at the center in the width direction of the front first region 30F1 by the area of the center in the width direction of the front first region 30F1. Specifically, as shown in FIG. 17, only one main groove 351 having a length in the longitudinal direction rather than the width direction is provided at the center in the width direction of the rear first region 30B1, while four main grooves 351 are provided at the center in the width direction of the front first region 30F1.

[0159] Among the absorbent core 30, the central portion in the width direction of the rear first region 30B1 is a portion where body pressure is likely to be applied when the wearer is in a sitting position or a supine sleeping position. Therefore, by reducing the area ratio of the groove 35 at the central portion in the width direction of the rear first region 30B1, even if strong body pressure is applied to the rear first region 30B1, the rewet amount of the excreted liquid from the groove region A1 can be reduced.

[0160] On the other hand, the front portion 30F of the absorbent core 30 is a portion where the wearer's excretion port abuts and excreted liquid is easily excreted, and is a portion where body pressure is less likely to be applied when the wearer is sitting, etc., compared to the rear portion 30B. In particular, compared to the front second region 30F2 where the wearer's lower thigh abuts and the front third region 30F3 that is easily adhered to the wearer by the body circumferential elastic members 211, 221, etc. of the diaper 1, the front first region 30F1 therebetween is less likely to be applied with the wearer's body pressure. Therefore, by increasing the area ratio of the groove 35 at the central portion in the width direction of the front first region 30F1, a large amount of excreted liquid excreted from the wearer can be quickly drawn into the absorbent core 30 from the groove region A1. Also, since body pressure is less likely to be applied, rewet is less likely to occur. In particular, when the wearer is male, since the front first region 30F1 is likely to abut the wearer's excretion port, the excreted liquid can be more effectively absorbed into the absorbent core 30.

[0161] Also, the absorbent core 30 of the fifth embodiment is also configured such that the upper layer core 31 and the lower layer core 32 are laminated, similar to the absorbent core 30 described in the previous embodiments, and at least a part of the groove region A1 is provided in the overlapping portion of the upper layer core 31 and the lower layer core 32. That is, the upper layer core 31 and the lower layer core 32 are laminated, and the groove region A1 is provided in a region where the basis weight of the absorbent core 30 is relatively high and the holding power of the excreted liquid is high. Therefore, even if a large amount of excreted liquid is absorbed into the absorbent core 30 from the groove region A1, rewet from the groove region A1 can be suppressed compared to a single-layer absorbent core.

[0162] In addition, in FIG. 17, an absorbent core 30 is illustrated in which the upper core 31 is shorter in length in the width direction and the longitudinal direction than the lower core 32. However, the present invention is not limited to this. For example, the lower core 32 may be shorter in length in the width direction and the longitudinal direction than the upper core 31. Also, the length of the upper core 31 in the width direction may be longer (or shorter) than the length of the lower core 32 in the width direction, but the length of the upper core 31 in the longitudinal direction may be shorter (or longer) than the length of the lower core 32 in the longitudinal direction. Further, in FIG. 17, the lower core 32 extends beyond both sides of the upper core 31 in the longitudinal direction. However, the present invention is not limited to this. For example, the upper core 31 may extend beyond both sides of the lower core 32 in the longitudinal direction. Also, on one side in the longitudinal direction, the lower core 32 may extend further in the longitudinal direction than the upper core 31, and on the other side in the longitudinal direction, the upper core 31 may extend further in the longitudinal direction than the lower core 32.

[0163] Also, much of the excreted fluid that has not been absorbed by the absorbent core 30 at the excretory opening contact portion flows to the rear side in the longitudinal direction through the central portion in the width direction of the absorbent core 30. Therefore, it is preferable that the groove 35 of the upper core 31 is provided at the central portion in the width direction of the rear first region 30B1. However, this is a region where body pressure is likely to be applied and rewetting is likely to occur. Therefore, as shown in FIG. 17, it is preferable that the upper core 31 located at the central portion in the width direction of the rear first region 30B1 has a region where only one main groove 351 having a length in the longitudinal direction longer than the width direction is located. That is, it is preferable that there is a region where a plurality of main grooves 351 are not arranged in the width direction. By doing so, the excreted fluid flowing from the excretory opening contact portion can be absorbed into the absorbent core 30 while diffusing in the longitudinal direction. Further, the area ratio of the groove region A1 can be kept at a small value, and the amount of rewetting from the groove region A1 can be reduced.

[0164] Note that, although different from FIG. 17, in a part of the front side (a portion close to the excretory opening contact portion) of the central portion in the width direction of the rear first region 30B1, a plurality of main grooves 351 may be arranged in the width direction. Also, a groove 35 extending in a direction different from the longitudinal direction may be provided at the central portion in the width direction of the rear first region 30B1, or the groove 35 may not be provided at all.

[0165] In addition, the comparison of the area ratio of the groove region A1 included in the upper core 31 and the confirmation of the number of groove regions A1 or the like can be performed by well-known methods. For example, when the absorbent core 30 (upper core 31) can be separated from or exposed from the diaper 1 and the groove region A1 can be visually confirmed, after partitioning the absorbent core 30 as shown in FIG. 17, the area ratio of the groove region A1 of the target site may be compared visually or the number may be confirmed. Alternatively, on the image data obtained by photographing the upper core 31 in the thickness direction, the groove region A1 (outline) may be specified, and the area of the groove region A1 may be actually calculated and compared using area calculation software or the like.

[0166] In addition, as described above, in a portion where the overlap of the superabsorbent polymer 34 is large, the amount of X-ray transmission decreases. Therefore, when the density (basis weight) of the superabsorbent polymer 34 in the groove region A1 is smaller than that in the non-groove region A2, the groove region A1 can be specified based on an image obtained by irradiating X-rays in the thickness direction of the upper core 31. That is, a density difference occurs between the groove region A1 and the non-groove region A2 in the X-ray image. Therefore, the groove region A1 may be visually specified based on the light and shade of the X-ray image, and the area ratio of the groove region A1 of the target site may be compared or the number may be confirmed. Alternatively, the X-ray image may be binarized to specify the groove region A1 (outline), and the area of the groove region A1 may be actually calculated and compared using area calculation software or the like.

[0167] In addition, much of the excreted liquid not absorbed by the absorbent core 30 at the excretory opening contact portion flows through the central portion in the width direction of the absorbent core 30 to the rear side in the longitudinal direction. Therefore, it is preferable to increase the average basis weight (g / m 2 ) of the absorbent core 30 (upper core 31 and lower core 32) at the central portion in the width direction of the rear first region 30B1 compared to the pair of widthwise side portions of the rear first region 30B1. Specifically, as shown in FIG. 17, in a part of the widthwise side portion (rectangular region) of the rear first region 30B1, neither the upper core 31 nor the lower core 32 is present, whereas in the central portion in the width direction, the upper core 31 and the lower core 32 are present throughout the entire area (the entire area of the rectangular region).

[0168] By doing so, the absorbent core 30 at the center in the width direction of the rear first region 30B1 can absorb and hold a large amount of excreted liquid flowing from the excretory opening contact portion. Also, the center in the width direction of the rear first region 30B1 is a site where the body pressure of the wearer is likely to be applied, but rewetting can be suppressed.

[0169] In addition, the excreted liquid that the absorbent core 30 located at the center in the width direction of the rear first region 30B1 could not completely absorb easily flows to the side portions in the width direction. Therefore, by providing the main groove 351 in the side portions in the width direction, while diffusing the excreted liquid in the longitudinal direction, it can be absorbed into the absorbent core 30. Thus, leakage of excreted liquid, particularly lateral leakage, can be suppressed.

[0170] Note that the comparison of the average basis weight of the absorbent core 30 can be performed by a well-known method. For example, the absorbent core 30 is separated from the diaper 1, and the absorbent core 30 is partitioned as shown in FIG. 17. Then, the absorbent cores 30 (the laminate of the upper core 31 and the lower core 32) respectively located at the center in the width direction and the side portions in the width direction of the rear first region 30B1 are cut out, and their respective weights (g) are measured. Also, the area a (m 2 ) of the center in the width direction of the rear first region 30B1 is measured. Then, the weights (g) of the absorbent cores 30 respectively located at the center in the width direction and the side portions in the width direction of the rear first region 30B1 are divided by the area a (m 2 ), and the basis weight (g / m 2 ) is calculated.

[0171] Also, the planar shape of the upper core 31 illustrated in FIG. 17 is an hourglass shape. The width of the upper core 31 is the narrowest in the front second region 30F2, and the width is wider on the front side and the rear side in the longitudinal direction than the front second region 30F2. The narrow-width portion (front second region 30F2) of the upper core 31 becomes the excretory opening contact portion or a site close thereto. Therefore, it is preferable to provide the groove region A1 in the side portions in the width direction of the portion where the width becomes wider on the rear side in the longitudinal direction than the narrow-width portion of the upper core 31.

[0172] By doing so, similar to the above, it is the excreted liquid that has flowed rearward from the excretion port contact portion through the central portion in the width direction of the absorbent core 30. The excreted liquid that could not be completely absorbed at the central portion in the width direction of the absorbent core 30 flows to the side portions in the width direction of the absorbent core 30. The excreted liquid can be absorbed into the absorbent core 30 while being diffused by the groove region A1. Therefore, leakage of the excreted liquid, particularly lateral leakage, can be suppressed.

[0173] Also, as shown in FIG. 18A, it is preferable that, between the groove region A1 of the upper core 31 located in the rear second region 30B2 and the groove region A1 of the upper core 31 located in the front second region 30F2 in the longitudinal direction, the upper core 31 has a region in which the non-groove region A2 is continuous from one end to the other end in its width direction.

[0174] By doing so, in the front second region 30F2 which becomes the excretion port contact portion or a site close thereto, the excreted liquid is absorbed into the absorbent core 30 by the groove region A1. The excreted liquid is firmly absorbed and held in the non-groove region A2 behind the front second region 30F2, that is, in the region where the basis weight of the absorbent core 30 is high, and rewet can be suppressed. Also, the excreted liquid that has flowed rearward without being completely absorbed by the absorbent core 30 located in the front second region 30F2 is absorbed into the absorbent core 30 while being diffused by the groove region A1 of the rear second region 30B2, and leakage of the excreted liquid can be suppressed.

[0175] Also, the value obtained by dividing the area of the groove region A1 of the upper core 31 located at the central portion in the width direction of the rear second region 30B2 by the area of the central portion in the width direction of the rear second region 30B2 is preferably larger than the value obtained by dividing the area of the groove region A1 of the upper core 31 located at the central portion in the width direction of the rear first region 30B1 by the area of the central portion in the width direction of the rear first region 30B1. Specifically, only one main groove 351 having a length in the longitudinal direction rather than the width direction is provided at the central portion in the width direction of the rear first region 30B1, whereas three main grooves 351 are provided at the central portion in the width direction of the rear second region 30B2.

[0176] In the rear second region 30B2 close to the attachment part of the discharge port, by increasing the area ratio of the groove region A1, a large amount of excreted liquid excreted from the wearer can be quickly absorbed into the absorbent core 30, and leakage of the excreted liquid can be suppressed. On the other hand, in the rear first region 30B1 where the body pressure of the wearer is likely to be applied, by reducing the area ratio of the groove region A1, rewetting can be suppressed.

[0177] However, it is not limited to the above. As in the modified example shown in FIG. 19, the same number (here, one) of main grooves as in the central portion in the width direction of the rear first region 30B1 may be provided also in the central portion in the width direction of the rear second region 30B2. For example, when targeting a wearer with a large excretion amount, as shown in FIG. 17, many groove regions A1 may be provided in the central portion in the width direction of the rear second region 30B2. On the other hand, when targeting a wearer with a small excretion amount, as shown in FIG. 19, the number of groove regions A1 provided in the central portion in the width direction of the rear second region 30B2 is at least sufficient to suppress leakage of the excreted liquid.

[0178] Also, the upper core 31 located in the central portion in the width direction of the front first region 30F1 preferably has a larger number of main grooves 351 that are longer in the longitudinal direction than in the width direction compared to the upper core 31 located in the central portion in the width direction of the front second region 30F2. In the upper core 31 of FIG. 17, two main grooves 351 are provided in the front second region 30F2, while four main grooves 351 are provided in the front first region 30F1. Preferably, the front first region 30F1 has a larger area ratio of the groove region A1 than the front second region 30F2.

[0179] As described above, the body pressure of the wearer is less likely to be applied to the front first region 30F1 compared to the front second region 30F2 where the crotch portion of the wearer abuts. Therefore, even if the number of main grooves 351 is increased, rewetting of the excreted liquid can be suppressed. Also, when the wearer is male, the relatively front part becomes the attachment part of the discharge port. Therefore, by increasing the number of main grooves 351 in the front first region 30F1, a large amount of excreted liquid discharged from the discharge port can be quickly diffused by the multiple main grooves 351 and absorbed into the absorbent core 30, and leakage of the excreted liquid can be suppressed.

[0180] Also, in the central portion in the width direction of the rear first region 30B1 and the central portion in the width direction of the rear second region 30B2, a main groove 351 is provided on the center line that bisects the rectangular region in the width direction. By doing so, the excreted liquid that has flowed rearward through the central portion in the width direction of the absorbent core 30 from the excretory opening contact portion is likely to flow into the groove region A1 and is likely to be absorbed inside the absorbent core 30.

[0181] On the other hand, in the central portion in the width direction of the front first region 30F1 and the central portion in the width direction of the front second region 30F2, the main groove 351 is not provided on the center line that bisects the rectangular region in the width direction, and the main grooves 351 are provided on both sides thereof. By doing so, it becomes difficult for the wearer's excretory opening to come into contact with the main groove 351, and the basis weight of the absorbent core 30 at the site that receives the most excreted liquid is ensured. Therefore, rewet can be effectively suppressed.

[0182] Also, as shown in FIG. 15, the diaper 1 has a pair of leak-proof wall portions 19 that can stand up on the skin side at both side portions in the width direction of the absorbent core 30 (absorbent body 10). Specifically, as shown in FIG. 16, the side sheet 14 is folded back from the side portion in the width direction of the non-skin side surface of the back sheet 13 toward the side portion in the width direction of the skin side surface of the top sheet 11. A leak-proof wall elastic member 15 is fixed to the inner end in the width direction of the folded-back side sheet 14 in a state of being extended in the longitudinal direction.

[0183] Also, as shown in FIG. 15, the side sheet 14 is joined to the skin side surface of the top sheet 11 by a first joining portion 191 and a second joining portion 192 to which an adhesive or the like is applied. The first joining portion 191 is provided extending from one end to the other end in the longitudinal direction of the absorbent body 10. The second joining portion 192 is provided at both ends in the longitudinal direction of the absorbent body 10 inside the first joining portion 191 in the width direction. Therefore, among the side sheet 14, the portion inside the width direction of the inner end (standing fulcrum) of the first joining portion 191 and the portion inside the longitudinal direction of the inner end (standing fulcrum) of the second joining portion 192 can stand up on the skin side, and that portion is the leak-proof wall portion 19.

[0184] When the diaper 1 has the leakage-preventing wall portion 19, when the diaper 1 in the deployed and stretched state (FIG. 15) is viewed in the thickness direction, it is preferable that the upper core 31 has a groove region A1 at least partially overlapping the leakage-preventing wall portion 19. By doing so, the excreted liquid blocked by the leakage-preventing wall portion 19 can be absorbed from the groove region A1 into the inside of the absorbent core 30, and leakage of the excreted liquid beyond the leakage-preventing wall portion 19 can be suppressed.

[0185] Also, at the site where the leakage-preventing wall portion 19 is provided, the skin of the wearer contacts via the side sheet 14 without directly contacting the surface sheet 11. Therefore, even if the excreted liquid re-wets from the groove region A1 overlapping the leakage-preventing wall portion 19 in the thickness direction, the wearer hardly feels the re-wetting, and a decrease in the wearing comfort of the diaper 1 can be prevented. Further, the leakage-preventing wall portion 19 standing up toward the skin side due to the contraction of the leakage-preventing wall elastic member 15 easily functions as a cushioning material, and it is difficult for the body pressure of the wearer to be applied at the site where the leakage-preventing wall portion 19 is provided. Therefore, even if the groove region A1 is provided at the site overlapping the leakage-preventing wall portion 19 in the thickness direction, re-wetting can be suppressed.

[0186] Also, as shown in FIG. 16, when the lower core 32 also has the superabsorbent polymer 34 in the same manner as the upper core 31, it is preferable that the average density of the superabsorbent polymer 34 in the entire upper core 31 is higher than the average density of the superabsorbent polymer 34 in the entire lower core 32.

[0187] Compared with the excreted liquid existing between the liquid-absorbing fibers, the excreted liquid held by the superabsorbent polymer 34 is difficult to move freely and is difficult to re-wet. Therefore, by increasing the average density of the superabsorbent polymer 34 in the upper core 31, the excreted liquid re-wetted from the lower core 32 to the upper core 31 can be firmly held by the superabsorbent polymer 34 in the upper core 31. Therefore, even when the body pressure of the wearer is applied to the absorbent core 30, re-wetting from the upper core 31 onto the surface sheet 11 can be suppressed.

[0188] Also, the lower core 32 of the fifth embodiment has slits 37 and 38 and does not have a groove region A3 (groove 36), but is not limited thereto. For example, the lower core 32 may have both the slits 37 and 38 and the groove region A3, or may have a configuration having the groove region A3 without the slits 37 and 38.

[0189] When the lower core 32 has the groove region A3, similar to the upper core 31, it is preferable to relatively reduce the area ratio of the groove region A3 of the lower core 32 located at the center in the width direction of the rear first region 30B1. For example, it is preferable to make it smaller than the area ratio of the groove region A3 of the lower core 32 located at the center in the width direction of the front first region 30F1. By doing so, the basis weight of the absorbent core 30 (upper core 31 and lower core 32) located at the center in the width direction of the rear first region 30B1 can be increased, and the excreted liquid can be firmly absorbed and retained. Therefore, even if the body pressure of the wearer is strongly applied to the rear first region 30B1, rewetting of the excreted liquid can be suppressed. On the other hand, by increasing the area ratio of the groove region A3 of the lower core 32 at the center in the width direction of the front first region 30F1, it is possible to suppress the stagnation of the excreted liquid at the boundary between the upper core 31 and the lower core 32, and the excreted liquid that has passed through the upper core 31 can be quickly absorbed and diffused inside the lower core 32. Therefore, it is possible to suppress the excreted liquid from overflowing and leaking from the skin side surface of the diaper 1 when the upper core 31 cannot absorb all the excreted liquid.

[0190] When viewing the absorbent core 30 in the thickness direction, the positions of the groove region A1 of the upper core 31 and the groove region A3 of the lower core 32 may coincide or may be offset. When the positions coincide, the excreted liquid absorbed from the groove region A1 of the upper core 31 can be quickly absorbed and diffused inside the lower core 32 by the groove region A3 of the lower core 32. On the other hand, when the positions of the groove regions A1 and A3 are offset, it is possible to suppress a local decrease in the basis weight of the absorbent core 30 in which the groove regions A1 and A3 are arranged, and to suppress rewetting from the groove regions A1 and A3.

[0191] As described above, embodiments of the present invention have been explained. However, the above embodiments are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Further, the present invention can be modified and improved without departing from its gist, and it goes without saying that equivalents of the present invention are included therein.

[0192] For example, the lower core 32 is not limited to being an absorbent core formed by shaping liquid-absorbent fibers 33 containing a superabsorbent polymer 34 into a predetermined shape. The lower core 32 may be a SAP sheet obtained by attaching a SAP layer to a hydrophilic sheet, an airlaid sheet formed by shaping liquid-absorbent fibers into a sheet by the airlaid method, or the like.

Explanation of Reference Numerals

[0193] 1 (panty type) diaper (absorbent article), 2 joint 10 absorbent body, 11 surface sheet, 12 intermediate sheet, 13 back sheet 14 side sheet, 15 leak-proof wall elastic member, 16 leg elastic member 17 crotch elastic member (elastic member), 18 cover sheet 20 exterior member, 21 front body circumferential part, 22 rear body circumferential part, 23 crotch part 211, 221 body circumferential elastic members, 212, 222 leg elastic members 30 absorbent core, 31 upper core, 32 lower core 33 liquid-absorbent fibers, 34 superabsorbent polymer 35 groove, 36 groove (second groove) 37 central slit (slit), 38 side slit 39 core wrap sheet A1 groove region, A2 non-groove region A3 groove region (second groove region), A4 non-groove region (second non-groove region)

Claims

1. An absorbent article having a longitudinal direction, a width direction, and a thickness direction, and having an absorbent core, wherein the absorbent core has an upper layer core having a superabsorbent polymer and a lower layer core disposed on the non-skin side in the thickness direction with respect to the upper layer core, the upper layer core has a groove in which a part of the upper layer core is recessed in the thickness direction, the groove has a length in a predetermined direction, the upper layer core has a groove region where the groove is provided and a non-groove region where the groove is not provided when viewed in the thickness direction, at least a part of the groove region is provided in a region where the upper layer core and the lower layer core overlap when viewed in the thickness direction, when the upper layer core is divided into two in the thickness direction, the part located on the skin side is defined as the skin side part, and the part located on the non-skin side is defined as the non-skin side part, the average density of the superabsorbent polymer in the skin side part of the groove region is lower than the average density of the superabsorbent polymer in the skin side part of the non-groove region, the absorbent core, has a central portion in the width direction and a pair of side portions in the width direction, which are partitioned by dividing its maximum width into three in the width direction, and has a front side portion located on the front side in the longitudinal direction with respect to a center line that bisects the absorbent article in the longitudinal direction in a deployed and stretched state, and a rear side portion located on the rear side in the longitudinal direction with respect to the center line, the rear side portion has a rear side first region that is a central region when its maximum length is divided into three in the longitudinal direction, the front side portion has a front side first region that is a central region when its maximum length is divided into three in the longitudinal direction, the value obtained by dividing the area of the groove region of the upper layer core located in the central portion in the width direction of the rear side first region by the area of the central portion in the width direction of the rear side first region is smaller than the value obtained by dividing the area of the groove region of the upper layer core located in the central portion in the width direction of the front side first region by the area of the central portion in the width direction of the front side first region, the central portion in the width direction of the rear side first region has a higher average basis weight of the absorbent core than the pair of side portions in the width direction of the rear side first region, the upper layer cores respectively located at the pair of side portions in the width direction of the rear side first region have the groove having a length in the longitudinal direction which is the predetermined direction. An absorbent article characterized by this.

2. The absorbent article according to Claim 1, The absorbent article is characterized in that the upper core located at the center in the width direction of the rear first region has a region where only one groove having a length in the longitudinal direction, which is the predetermined direction, is located.

3. The absorbent article according to claim 1 or 2, wherein the rear portion has a rear second region on the front side in the longitudinal direction than the rear first region, the front portion has a front second region on the rear side in the longitudinal direction than the front first region, The absorbent article is characterized in that, between the groove regions of the upper core located in the rear second region and the groove regions of the upper core located in the front second region in the longitudinal direction, the upper core has a region where the non-groove regions are continuous from one end to the other end in the width direction thereof.

4. An absorbent article having a longitudinal direction, a width direction, and a thickness direction, and having an absorbent core, wherein the absorbent core has an upper core having a superabsorbent polymer and a lower core disposed on the non-skin side in the thickness direction than the upper core, the upper core has a groove in which a part of the upper core is recessed in the thickness direction, the groove has a length in a predetermined direction, the upper core has a groove region provided with the groove and a non-groove region not provided with the groove when viewed in the thickness direction, at least a part of the groove region is provided in a region where the upper core and the lower core overlap when viewed in the thickness direction, when the upper core is divided into two in the thickness direction, the part located on the skin side is defined as the skin side part and the part located on the non-skin side is defined as the non-skin side part, the average density of the superabsorbent polymer in the skin side part of the groove region is lower than the average density of the superabsorbent polymer in the skin side part of the non-groove region, the absorbent core has a central portion in the width direction and a pair of side portions in the width direction, which are partitioned by dividing its maximum width into three in the width direction, and has a front portion located on the front side in the longitudinal direction than a center line that bisects the absorbent article in the longitudinal direction in a developed and stretched state, and a rear portion located on the rear side in the longitudinal direction than the center line, the rear portion has a rear first region, which is a central region when its maximum length is divided into three in the longitudinal direction, the front portion has a front first region, which is a central region when its maximum length is divided into three in the longitudinal direction, The value obtained by dividing the area of the groove region of the upper core located at the center in the width direction of the rear first region by the area of the center in the width direction of the rear first region is smaller than the value obtained by dividing the area of the groove region of the upper core located at the center in the width direction of the front first region by the area of the center in the width direction of the front first region. The rear side portion has a rear second region on the front side in the longitudinal direction than the rear first region. An absorbent article, wherein the value obtained by dividing the area of the groove region of the upper core located at the center in the width direction of the rear second region by the area of the center in the width direction of the rear second region is larger than the value obtained by dividing the area of the groove region of the upper core located at the center in the width direction of the rear first region by the area of the center in the width direction of the rear first region. **Claim 5**: An absorbent article having a longitudinal direction, a width direction, and a thickness direction, and having an absorbent core. The absorbent core has an upper core having a superabsorbent polymer and a lower core disposed on the non-skin side in the thickness direction than the upper core. The upper core has a groove in which a part of the upper core is recessed in the thickness direction. The groove has a length in a predetermined direction. When viewed in the thickness direction, the upper core has a groove region provided with the groove and a non-groove region not provided with the groove. When viewed in the thickness direction, at least a part of the groove region is provided in a region where the upper core and the lower core overlap. When the upper core is divided into two in the thickness direction, the part located on the skin side is defined as the skin side part, and the part located on the non-skin side is defined as the non-skin side part. The average density of the superabsorbent polymer in the skin side part of the groove region is lower than the average density of the superabsorbent polymer in the skin side part of the non-groove region. The absorbent core has a central portion in the width direction and a pair of side portions in the width direction, which are partitioned by dividing its maximum width into three equal parts in the width direction. and has a front side portion located on the front side in the longitudinal direction than a center line that bisects the absorbent article in the longitudinal direction in a developed and stretched state, and a rear side portion located on the rear side in the longitudinal direction than the center line. The rear side portion has a rear first region, which is a central region when its maximum length is divided into three equal parts in the longitudinal direction. The front side portion has a front first region, which is a central region when its maximum length is divided into three equal parts in the longitudinal direction. The value obtained by dividing the area of the groove region of the upper core located at the center in the width direction of the rear side first region by the area of the center in the width direction of the rear side first region is smaller than the value obtained by dividing the area of the groove region of the upper core located at the center in the width direction of the front side first region by the area of the center in the width direction of the front side first region. The front side has a front side second region on the rear side in the longitudinal direction than the front side first region. The upper core located at the center in the width direction of the front side first region has a larger number of grooves having a length in the longitudinal direction, which is the predetermined direction, than the upper core located at the center in the width direction of the front side second region. The absorbent article is characterized by this.

6. The absorbent article according to any one of Claims 1 to 5, The absorbent article has a pair of leak-proof wall portions that can stand up on the skin side at both side portions in the width direction of the absorbent core. When the absorbent article in the deployed and stretched state is viewed in the thickness direction, the upper core has a groove region that at least partially overlaps with the leak-proof wall portion. The absorbent article is characterized by this.

7. The absorbent article according to any one of Claims 1 to 6, The lower core has a superabsorbent polymer. The average density of the superabsorbent polymer in the upper core is higher than the average density of the superabsorbent polymer in the lower core. The absorbent article is characterized by this.

8. The absorbent article according to any one of Claims 1 to 7, The average density of the superabsorbent polymer in the non-skin side portion of the non-groove region is lower than the average density of the superabsorbent polymer in the skin side portion of the non-groove region. The absorbent article is characterized by this.

9. The absorbent article according to any one of Claims 1 to 8, The groove is a groove that is recessed from the skin side surface of the upper core to the non-skin side in the thickness direction. The absorbent article is characterized by this.

10. The absorbent article according to Claim 9, The average density of the superabsorbent polymer in the non-skin side portion of the groove region is lower than the average density of the superabsorbent polymer in the skin side portion of the non-groove region. The absorbent article is characterized by this.

11. The absorbent article according to Claim 10, The upper core includes liquid-absorbent fibers in addition to the superabsorbent polymer. The absorbent article is characterized in that the average density of the liquid-absorbent fibers in the non-muscle side portion of the non-groove region is higher than the average density of the liquid-absorbent fibers in the non-muscle side portion of the groove region.

12. The absorbent article according to any one of Claims 1 to 11, wherein the lower layer core includes a superabsorbent polymer, when the lower layer core is divided into two in the thickness direction, with the portion located on the skin side being the skin side portion and the portion located on the non-skin side being the non-skin side portion, in at least a part of the lower layer core, the average density of the superabsorbent polymer in the skin side portion of a certain region of the lower layer core is higher than the average density of the superabsorbent polymer in the non-skin side portion of the region of the upper layer core facing the certain region. The absorbent article is characterized by this.

13. The absorbent article according to any one of Claims 1 to 12, wherein the groove has a main groove having a length in the longitudinal direction which is the predetermined direction, and a sub-groove extending in the width direction from the main groove, a plurality of the main grooves are arranged at intervals in the width direction, and a plurality of the sub-grooves extend in the width direction at intervals in the longitudinal direction from the main groove. The absorbent article is characterized by this.

14. The absorbent article according to any one of Claims 1 to 13, wherein the lower layer core has a superabsorbent polymer and has a second groove in which a part of the lower layer core is recessed in the thickness direction, the second groove has a length in the longitudinal direction, the lower layer core has, when viewed in the thickness direction, a second groove region where the second groove is provided and a second non-groove region where the second groove is not provided, at least a part of the second groove region is provided in the region where the upper layer core and the lower layer core overlap when viewed in the thickness direction, when the lower layer core is divided into two in the thickness direction, with the portion located on the skin side being the skin side portion and the portion located on the non-skin side being the non-skin side portion, the average density of the superabsorbent polymer in the skin side portion of the second groove region is lower than the average density of the superabsorbent polymer in the skin side portion of the second non-groove region. The absorbent article is characterized by this.

15. The absorbent article according to Claim 14, wherein the average density of the superabsorbent polymer in the non-skin side portion of the second non-groove region is lower than the average density of the superabsorbent polymer in the skin side portion of the second non-groove region. The absorbent article is characterized by this.

16. An absorbent article according to claim 14 or 15, wherein the second groove is a groove that is recessed from the non-skin side surface of the lower core toward the skin side in the thickness direction, and the absorbent article is characterized thereby.

17. An absorbent article according to any one of claims 14 to 16, wherein when viewed in the thickness direction, the groove region of the upper core has a portion that overlaps with the second groove region of the lower core, and the absorbent article is characterized thereby.

18. An absorbent article according to any one of claims 1 to 17, wherein the lower core has a slit that penetrates the lower core in the thickness direction at the central portion in the width direction of the region where the wearer's crotch contacts, the slit has a length in the longitudinal direction, when viewed in the thickness direction, the slit of the lower core overlaps with the upper core, and in at least a partial region of the slit of the lower core, the slit does not overlap with the groove region of the upper core, and the absorbent article is characterized thereby.

19. An absorbent article according to claim 18, wherein an elastic member that expands and contracts in the longitudinal direction is disposed in the region where the wearer's crotch contacts, when viewed in the thickness direction, all regions of the slit of the lower core do not overlap with the groove region of the upper core, when viewed in the thickness direction, the slit has a portion that overlaps with the elastic member, and the absorbent article is characterized thereby.

20. An absorbent article according to claim 18 or 19, wherein the groove region has a length in the longitudinal direction which is the predetermined direction, the upper core has a region in which the non-groove region is continuous from one end to the other end in the width direction on the rear side in the longitudinal direction with respect to the slit, in the longitudinal direction, the rear end of the lower core is located more rearward than the rear end of the upper core, and the absorbent article is characterized thereby.

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