ABSORBENT PRODUCTS

Abstract

The invention relates to an absorbent product (1) having an upper core (31) and a lower core (32), the lower core (32) having grooves (36) which are concave in the direction of its thickness and length in the specified direction, the lower core (32) having a grooved area where grooves (36) are arranged and a non-grooved area where grooves (36) are not made, at least part of the grooved area is arranged in the area where the upper core (31) and lower core (32) are stacked when viewed from the thickness direction, and the average density of the highly absorbent polymer (34) in the skin-side of the grooved area is lower than the average density of the highly absorbent polymer (34) in the skin-side of the non-grooved area.

Description

absorbent articles

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

[0002] Patent Document 1 discloses an absorbent article with a two-layer absorbent body consisting of an upper absorbent body and a lower absorbent body. A slit is provided at least in the widthwise center of the upper absorbent body, penetrating the upper absorbent body in the thickness direction. The upper absorbent body has a higher weight ratio of superabsorbent polymer to pulp fiber than the lower absorbent body. This allows excreted liquid to be supplied to the upper absorbent body, but preferentially through the slit to the lower absorbent body. After the lower absorbent body is saturated with liquid, the liquid absorbed by the lower absorbent body is sucked up by the upper absorbent body and retained by the superabsorbent polymer of the upper absorbent body. This is said to provide excellent rewet (backflow) prevention.

[0003] JP 2017-63923 A

[0004] In a two-layer absorbent body, the absorption capacity of the absorbent body can be increased. However, excrement tends to stagnate in the space at the boundary between the upper absorbent body (upper core) and the lower absorbent body (lower core) in the thickness direction. This reduces the absorption capacity of the lower absorbent body, preventing the absorption performance of the lower absorbent body from being effectively utilized. Furthermore, when a relatively large slit is provided in the upper absorbent body as in Patent Document 1, excrement tends to stagnate in the space of the slit. Patent Document 1 discloses that the weight ratio of superabsorbent polymer in the lower absorbent body is reduced to absorb excrement and diffuse it over a wide area. However, this alone has a limit to the ability of the lower absorbent body to absorb and diffuse excrement supplied locally through the slit, and it can be said that the diffusion of excrement in the lower absorbent body is insufficient.

[0005] Therefore, the present invention has been made in consideration of the above-mentioned problems, and its purpose is to suppress stagnation of excreted liquid at the boundary between the upper core and the lower core in an absorbent article in which an upper core and a lower core are stacked, and to increase the diffusion of excreted liquid in the lower core, thereby effectively utilizing the absorption performance of the lower core.

[0006] The primary invention for achieving the above object is an absorbent article having a longitudinal direction, a width direction, and a thickness direction and including an absorbent core, the absorbent core including an upper core and a lower core disposed on the non-skin side of the upper core in the thickness direction, the lower core including a superabsorbent polymer and a groove formed by a recess in a portion of the lower core in the thickness direction, the groove having a length in a predetermined direction, the lower core including a groove region having the groove and a non-groove region not having the groove, at least a portion of the groove region being formed in a region where the upper core and the lower core overlap in the thickness direction, and when the lower core is divided in half 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, the average density of the superabsorbent polymer in the 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. Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0007] According to the present invention, in an absorbent article in which an upper core and a lower core are stacked, stagnation of excreted liquid at the boundary between the upper core and the lower core can be suppressed, and the diffusion of excreted liquid in the lower core can be increased, thereby effectively utilizing the absorption performance of the lower core.

[0008] FIG. 8A is a schematic perspective view of a pants-type diaper 1 (hereinafter also referred to as "diaper"). It is a schematic plan view of the diaper 1 in an unfolded and stretched state, as viewed from the skin side. It is a schematic cross-sectional view taken along line a-a in FIG. 2. It is a plan view of the upper core 31, as viewed from the skin side in the thickness direction. It is a plan view of the lower core 32, as viewed from the skin side in the thickness direction. It is a plan view of the stacked upper core 31 and lower core 32, as viewed from the skin side in the thickness direction. It is a schematic cross-sectional view of a portion of the upper core 31 and the lower core 32. FIG. 8A is a schematic cross-sectional view taken along line II in FIG. 6, and FIG. 8B is a schematic cross-sectional view taken along line II-II in FIG. 6. FIG. 9A is a schematic perspective view of the core wrap sheet 39, and FIG. 9B is an explanatory diagram of a modified arrangement of the core wrap sheet 39. FIGS. 10A and 10B are explanatory diagrams of modified grooves 35 and 36. FIGS. 11A and 11B are explanatory diagrams of modified grooves 35 and 36. 15A is a schematic cross-sectional view of an absorbent core 30 in a second embodiment. FIG. 15B is a schematic cross-sectional view of an absorbent core 30 in a third embodiment. FIG. 14A and FIG. 14B are schematic cross-sectional views of an absorbent core 30 in a fourth embodiment. FIG. 15B is a schematic plan view of a diaper 1 in a fifth embodiment in an unfolded and stretched state, as viewed from the skin side. FIG. 15B is a schematic cross-sectional view taken along line A-A in FIG. 15A. FIG. 15C is a plan view of a laminated upper core 31 and a lower core 32, as viewed from the non-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 non-skin side in the thickness direction. FIG. 15C is a schematic cross-sectional view of an absorbent core 30 in a modified fifth embodiment, as viewed from the non-skin side in the thickness direction.

[0009] The present specification and the accompanying drawings make clear at least the following: An absorbent article having a longitudinal direction, a width direction, and a thickness direction and having an absorbent core, the absorbent core comprising an upper core and a lower core arranged on the non-skin side of the upper core in the thickness direction, the lower core containing a superabsorbent polymer and having a groove formed by a portion of the lower core being recessed in the thickness direction, the groove having a length in a predetermined direction, the lower core having, as viewed in the thickness direction, a groove region in which the groove is provided and a non-groove region in which the groove is not provided, at least a portion of the groove region being provided in a region where the upper core and the lower core overlap as viewed in the thickness direction, when the lower core is divided in half in the thickness direction, the portion located on the skin side is defined as a skin-side portion and the portion located on the non-skin side is defined as a non-skin-side portion, the absorbent article characterized in that

[0010] In this absorbent article, excreted liquid that has passed through the upper core can be drawn into the groove region in the skin-facing portion of the lower core, where the density of the superabsorbent polymer is low, or can be dropped into the gaps in the grooves. This allows the excreted liquid to be diffused in a predetermined direction along the groove region. This prevents excreted liquid from stagnating at the boundary between the upper and lower cores in the thickness direction, improving the diffusibility of excreted liquid in the lower core. This effectively utilizes the absorption performance of the lower core. Furthermore, excreted liquid absorbed in the skin-facing portion of the non-groove region of the lower core is retained by the superabsorbent polymer, preventing excreted liquid from rewetting into the upper core.

[0011] The absorbent article is characterized in that the absorbent core has a widthwise central portion and a pair of widthwise side portions that are partitioned by dividing its maximum width into thirds in the width direction, and has a front portion located in front of a center line that divides the absorbent article in half in the longitudinal direction when it is in an unfolded and stretched state, and a rear portion located behind the center line in the longitudinal direction, the rear portion having a rear first region that is a central region when its maximum length is divided into thirds in the longitudinal direction, and the front portion having a front first region that is a central region when its maximum length is divided into thirds in the longitudinal direction, and the area of ​​the groove region of the lower core located in the widthwise central portion of the rear first region divided by the area of ​​the widthwise central portion of the rear first region is smaller than the area of ​​the groove region of the lower core located in the widthwise central portion of the front first region divided by the area of ​​the widthwise central portion of the front first region.

[0012] In this absorbent article, the area ratio of the groove region in the lower core is small in the widthwise center of the rear first region, where the wearer's body pressure is likely to be applied, thereby reducing the amount of excreted fluid rewet from the groove region. On the other hand, in the front first region, which is the excretory opening contact area or a region close to it, the area ratio of the groove region in the lower core is large, allowing the excreted fluid that has passed through the upper core to be quickly drawn into the lower core and diffused by the groove region. This prevents excreted fluid from stagnating at the boundary between the upper and lower cores, which prevents the upper core from being able to fully absorb the excreted fluid and causes the excreted fluid to overflow and leak from the skin side of the absorbent article.

[0013] Such an absorbent article is characterized in that the lower core located in the widthwise center of the rear first region has an area in which only one groove having a length in the longitudinal direction, which is the specified direction, is located.

[0014] In this absorbent article, the widthwise center of the rear first region, where the wearer's body pressure is likely to be applied, has an area where the groove regions are not aligned in the widthwise direction, thereby suppressing rewetting. Furthermore, excreted liquid that flows from the excretion opening contact portion to the rear first region and passes through the upper core can be quickly drawn into the lower core and diffused by the groove regions of the lower core. This suppresses leakage of excreted liquid.

[0015] Such an absorbent article is characterized in that the average basis weight of the absorbent core is higher in the widthwise central portion of the rear first region than in the pair of widthwise side portions of the rear first region, and the lower cores located in each of the pair of widthwise side portions of the rear first region have grooves having a length in the longitudinal direction, which is the specified direction.

[0016] This absorbent article has enhanced absorption and retention of excreted liquid in the widthwise center of the rear first region, where the wearer's body pressure is likely to be applied, thereby preventing rewetting. Furthermore, excreted liquid that flows from the excretion opening contact portion to the rear first region is quickly drawn into the lower core by the groove regions of the lower core located at the widthwise sides, allowing it to be dispersed in the longitudinal direction. This prevents leakage (side leakage) of excreted liquid.

[0017] Such an absorbent article is characterized in that the rear portion has a rear second region forward in the longitudinal direction from the rear first region, and the front portion has a front second region rearward in the longitudinal direction from the front first region, and the lower core has a region in which the non-groove region is continuous from one end to the other end in the width direction between the groove region of the lower core located in the rear second region and the groove region of the lower core located in the front second region in the longitudinal direction.

[0018] In this absorbent article, the groove region of the lower core located in the front second region, which is the excretory opening contact area or a region close to it, allows a large amount of excreted liquid to be quickly drawn into and diffused from the upper core into the lower core. Absorbed excreted liquid can be retained in the non-groove region, preventing rewetting. Furthermore, excreted liquid that cannot be absorbed in the front second region and flows to the rear can be quickly drawn into and diffused by the groove region of the lower core located in the rear second region. This prevents leakage of excreted liquid.

[0019] Such an absorbent article is characterized in that the rear portion has a rear second region located forward in the longitudinal direction of the rear first region, and the value obtained by dividing the area of ​​the groove region of the lower core located in the widthwise center of the rear second region by the area of ​​the widthwise center of the rear second region is greater than the value obtained by dividing the area of ​​the groove region of the lower core located in the widthwise center of the rear first region by the area of ​​the widthwise center of the rear first region.

[0020] In this absorbent article, the area ratio of the groove region of the lower core is small in the widthwise center of the first rear region, where the wearer's body pressure is likely to be applied, thereby suppressing rewetting. On the other hand, in the second rear region, which is closer to the excretory opening contact area, the area ratio of the groove region of the lower core is large, so that excreted liquid that has passed through the upper core can be quickly drawn into the lower core by the groove region of the lower core and diffused, thereby suppressing leakage of excreted liquid.

[0021] Such an absorbent article is characterized in that the front portion has a front second region located rearward in the longitudinal direction from the front first region, and the lower core located in the widthwise center of the front first region has a larger number of grooves having a length in the longitudinal direction, which is the specified direction, than the lower core located in the widthwise center of the front second region.

[0022] In this absorbent article, the front first region is less susceptible to the wearer's body pressure than the front second region, which contacts the wearer's crotch area, and therefore is less likely to rewet, even if the front first region has a large number of grooves. Furthermore, if the wearer is a man, the front first region contacts the excretory opening or is close to it, so that excretory fluid that is excreted from the excretory opening and passes through the upper core can be quickly drawn into the lower core by the many grooves in the lower core and diffused. This reduces leakage of excretory fluid.

[0023] The absorbent article is characterized in that the average basis weight of the lower core is higher than the average basis weight of the upper core.

[0024] In such an absorbent article, the upper core has a relatively low water absorption and retention capacity, but the grooves in the lower core allow excreted liquid that passes through the upper core to be quickly drawn into the lower core and diffused, thereby more effectively preventing leakage of excreted liquid.

[0025] Such an absorbent article is characterized in that the absorbent article has a pair of leak-proof wall portions that can stand up on the skin side on both sides of the absorbent core in the width direction, and when the absorbent article in an unfolded and stretched state is viewed in the thickness direction, the lower core has a groove region that at least partially overlaps with the leak-proof wall portions.

[0026] In this absorbent article, excrement that has been blocked by the leakage preventing walls and absorbed by the upper core can be quickly drawn into the lower core by the groove regions of the lower core while being diffused. Furthermore, the leakage preventing walls function as a buffer in the areas where the excrement is present, making it difficult for body pressure to be applied, thereby preventing rewetting in the groove regions.

[0027] Such an absorbent article is characterized in that the upper core contains a superabsorbent polymer, and 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.

[0028] In such an absorbent article, even if excreted liquid absorbed by the lower core rewet onto the upper core (especially if excreted liquid is likely to rewet onto the upper core from the groove region of the lower core), the excreted liquid is retained by the superabsorbent polymer of the upper core, thereby preventing rewetting onto the skin side of the absorbent article.

[0029] Such an absorbent article is characterized in that 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.

[0030] In this absorbent article, excreted liquid that passes through the groove regions of the lower core and migrates to the non-skin side portion is easily absorbed by the non-skin side portion of the non-groove region, where the density of the superabsorbent polymer is low. This increases the diffusibility of excreted liquid in the non-skin side portion of the lower core. Furthermore, excreted liquid that migrates to the non-skin side portion of the non-groove region is absorbed by the skin side portion of the non-groove region and retained by the superabsorbent polymer, thereby preventing rewetting of excreted liquid into the upper core.

[0031] The absorbent article is characterized in that the groove is a groove recessed from the non-skin side of the lower core to the skin side in the thickness direction.

[0032] In such an absorbent article, the groove region of the lower core has improved liquid permeability to the non-skin side portion (the groove space), which allows the excreted liquid to be drawn firmly to the non-skin side portion of the lower core and then diffused along the grooves, thereby making effective use of the absorption capacity of the lower core.

[0033] Such an absorbent article is characterized in that the upper core comprises a superabsorbent polymer, and when the upper core is divided in half in the thickness direction, the portion located on the skin side is the skin side portion and the portion located away from the skin side is the non-skin side portion, and 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 opposite the certain region.

[0034] With such an absorbent article, the rate of liquid migration from the upper core to the lower core can be appropriately suppressed, which increases the diffusibility of excreted liquid in the upper core and allows the excreted liquid to be absorbed over a wide area in the lower core.

[0035] Such an absorbent article is characterized in that the grooves have a main groove having a length in the longitudinal direction, which is the predetermined direction, and a minor groove extending from the main groove in the width direction, wherein multiple main grooves are arranged at intervals in the width direction, and multiple minor grooves extend from the main groove in the width direction at intervals in the longitudinal direction.

[0036] In such an absorbent article, the lower core can diffuse excrement in the longitudinal direction and also in the width direction along the minor grooves, and the flexibility of the lower core is increased, allowing the lower core to easily deform to conform to the wearer's body.

[0037] The absorbent article is characterized in that the upper core contains a superabsorbent polymer and has a second groove formed by a recess in a portion of the upper core in the thickness direction, the second groove having a length in the longitudinal direction, the upper core having, when viewed in the thickness direction, a second groove region in which the second groove is provided and a second non-groove region in which the second groove is not provided, and at least a portion 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, and when the upper core is divided in half in the thickness direction, the portion located on the skin side is defined as the skin side portion and the portion located away from the skin side is defined as 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.

[0038] In this absorbent article, excreted liquid excreted on the skin-side surface of the upper core can be drawn into the skin-side portion of the second groove region, where the density of the superabsorbent polymer is low, or can be dropped into the space in the second groove region. This improves the diffusibility of excreted liquid in the upper core. The lower core receives and absorbs the excreted liquid dispersed in the upper core, improving the diffusibility of excreted liquid in the lower core. Furthermore, excreted liquid absorbed on the skin-side portion of the second non-groove region is retained by the superabsorbent polymer, preventing rewetting of excreted liquid onto the skin-side surface of the upper core.

[0039] Such an absorbent article is characterized in that 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.

[0040] In this absorbent article, excreted liquid that passes through the second groove region of the upper core and migrates to the non-skin side portion is more likely to be absorbed by the non-skin side portion of the second non-groove region, which has a lower density of superabsorbent polymer. This increases the diffusibility of excreted liquid in the non-skin side portion of the upper core. Furthermore, excreted liquid that migrates to the non-skin side portion of the second non-groove region is absorbed by the skin side portion of the second non-groove region and retained by the superabsorbent polymer, thereby preventing excreted liquid from rewetting onto the skin side of the upper core.

[0041] The absorbent article is characterized in that the second groove is a groove recessed from the skin side of the upper core to the non-skin side in the thickness direction.

[0042] In this absorbent article, excreted liquid discharged into the upper core can be immediately dropped into the space of the second groove of the upper core and diffused, thereby preventing the excreted liquid from overflowing onto the skin-facing side of the upper core.

[0043] The absorbent article is characterized in that, when viewed in the thickness direction, the groove region of the lower core has a portion that overlaps with the second groove region of the upper core.

[0044] In this absorbent article, most of the excreted liquid absorbed in the second groove region of the upper core can be drawn into the groove region of the lower core, thereby preventing the excreted liquid from overflowing onto the skin-facing side of the upper core.

[0045] Such an absorbent article is characterized in that the lower core has a slit that penetrates the lower core in the thickness direction at the center of the width direction of the area 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 core overlaps with the upper core, and at least a portion of the slit of the lower core does not overlap with the second groove area of ​​the upper core.

[0046] In this absorbent article, the slits allow the widthwise central portion of the absorbent core to easily deform so as to convex toward the skin, improving the fit of the absorbent core to the crotch region of the wearer. Furthermore, the overlap of the portion of the absorbent core where the slits are arranged with the second non-groove region of the upper core prevents the rigidity of the absorbent core from decreasing too much, thereby suppressing the absorbent core from losing its shape.

[0047] Such an absorbent article is characterized in that an elastic member that stretches in the longitudinal direction is arranged in the area where the wearer's crotch comes into contact, and when viewed in the thickness direction, the entire area of ​​the slit in the lower core does not overlap with the second groove area of ​​the upper core, and when viewed in the thickness direction, the slit has a portion that overlaps with the elastic member.

[0048] In this absorbent article, the slits and the groove regions of the upper core do not overlap in the thickness direction, making it difficult for excrement to migrate from the upper core to the slits and preventing excrement from stagnating in the slits. Furthermore, the elastic member promotes the deformation of the absorbent core, which causes the slits in the lower core to convexly deform toward the skin. This improves the fit of the absorbent core to the wearer's crotch area and also prevents excrement from stagnating when the slits in the lower core fold.

[0049] Such an absorbent article is characterized in that the lower core has a pair of side slits that penetrate the lower core in the thickness direction on the widthwise sides of the area where the wearer's crotch contacts, and the groove area is provided outside the pair of side slits in the widthwise direction and at a position that overlaps with at least a portion of the pair of side slits in the longitudinal direction.

[0050] In such an absorbent article, the side slits in the lower core cause the widthwise sides of the absorbent core to rise toward the skin, making it easier to fit around the wearer's groin. The raised sides of the absorbent core are made more flexible by the groove regions, making them more likely to deform along the wearer's groin, improving the fit.

[0051] Such an absorbent article is characterized in that the lower core has a slit penetrating the lower core in the thickness direction in the widthwise center of the area where the wearer's crotch contacts, the slit has a length in the longitudinal direction, the groove area has a length in the longitudinal direction which is the specified direction, the lower core has a region in the longitudinal direction rear of the slit in which the non-groove area is continuous from one end to the other end in the width direction, and the rear end of the longitudinal direction of the upper core is located in the region in which the non-groove area is continuous.

[0052] In such an absorbent article, the lower core is easily bent in the longitudinal direction along the rear end of the upper core, so that the rear end of the lower core easily fits the buttocks of the wearer, improving the fit of the absorbent core.

[0053] Such an absorbent article is characterized in that the lower layer core extends longitudinally outward beyond the longitudinal ends of the upper layer core, and the groove region is provided in the portion of the lower layer core that extends longitudinally outward beyond the upper layer core.

[0054] In this absorbent article, the lower core can diffuse excrement received from the upper core to the longitudinal ends of the lower core that do not overlap with the upper core in the thickness direction. In addition, the groove regions increase the flexibility of the ends of the lower core, making it easier to fit the lower abdomen and buttocks of the wearer.

[0055] Hereinafter, an example of an absorbent article according to the present embodiment will be described using a pants-type diaper for adults. However, the absorbent article is not limited to this, and other absorbent articles include, for example, tape-type diapers, diapers for babies, light incontinence pads, sanitary napkins, etc.

[0056] ===Basic Structure of Pants-Type Diaper 1=== Fig. 1 is a schematic perspective view of the pants-type diaper 1 (hereinafter also referred to as "diaper"). Fig. 2 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as seen from the skin side. Fig. 3 is a schematic cross-sectional view taken along line a-a in Fig. 2.

[0057] The unfolded state of the diaper 1 refers to a state in which the diaper 1 is unfolded after the joints 2 of the front waistband 21 and the rear waistband 22, which will be described later, are released. The stretched state of the diaper 1 refers to a state in which the diaper 1 is stretched without wrinkles. Specifically, this refers to a state in which the diaper 1 is stretched until the dimensions of each material constituting the diaper 1 match or approximate the dimensions of the material alone, without being affected by the elastic members of the diaper 1.

[0058] The diaper 1 in pants state has a vertical direction, a width direction, and a thickness direction, and includes an absorbent main body 10 and an outer cover member 20. In the vertical direction, the side where the waist opening BH of the diaper 1 is located is referred to as the upper side, and the opposite side is referred to as the lower side. The longitudinal direction of the diaper 1 in the unfolded state corresponds to the vertical direction of the diaper 1 in pants state and corresponds to the longitudinal direction of the absorbent main body 10. In the longitudinal direction, the side that contacts the wearer's abdomen is referred to as the front side, and the side that contacts the wearer's buttocks is referred to as the rear side. In addition, in the thickness direction, the side that contacts the wearer's skin is referred to as the skin side, and the opposite side is referred to as the non-skin side.

[0059] The outer member 20 is disposed closer to the skin than the absorbent body 10, and has a front waist portion 21, a rear waist portion 22, and a crotch portion 23. The diaper 1 in an unfolded state is folded in half approximately at the center in the longitudinal direction, and both ends in the width direction of the front waist portion 21 and the rear waist portion 22 are joined by welding or the like to form a pair of joining portions 2, thereby forming the diaper 1 into a pants-type diaper.

[0060] A plurality of waistline elastic members 211, 221 (e.g., rubber thread) extending along the width direction are arranged at intervals in the up-down direction (longitudinal direction) in the front waistline portion 21 and the rear waistline portion 22. A plurality of legline elastic members 212, 222 (e.g., rubber thread) are also arranged along the leg openings LH in the front waistline portion 21 and the rear waistline portion 22. The waistline elastic members 211, 221 and the legline elastic members 212, 222 are fixed in a stretched state between two layers of sheets (e.g., nonwoven fabric).

[0061] The crotch portion 23 is formed of a sheet (for example, nonwoven fabric) that connects the front waistline portion 21 and the rear waistline portion 22. However, the exterior member 20 does not necessarily have to have the crotch portion 23.

[0062] The absorbent body 10 comprises an absorbent core 30 that absorbs and retains excreted liquid, a liquid-permeable top sheet 11 (e.g., a nonwoven fabric or a resin film with openings) arranged on the skin side of the absorbent core 30, a liquid-permeable intermediate sheet 12 arranged between the top sheet 11 and the absorbent core 30, a liquid-impermeable back sheet 13 (e.g., a resin film) arranged on the non-skin side of the absorbent core 30, a pair of side sheets 14 (e.g., a hydrophobic nonwoven fabric) arranged on the widthwise sides of the absorbent body 10, a leakage-proof wall elastic member 15, leg elastic members 16, crotch elastic members 17, and a cover sheet 18 that covers the crotch elastic member 17 from the non-skin side.

[0063] Although not shown in detail, the side sheets 14 are folded back from the widthwise side of the non-skin-facing side of the back sheet 13 toward the widthwise side of the skin-facing side of the top sheet 11. The leakage preventing wall elastic members 15 and the leg opening elastic members 16 are fixed to the side sheets 14 in a state stretched in the longitudinal direction. The leakage preventing wall elastic members 15 are arranged at the tip of the side sheets 14, which are folded back widthwise inward on the skin-facing side of the top sheet 11. The leg opening elastic members 16 are arranged at the widthwise side of the absorbent main body 10. The crotch elastic members 17 are arranged in the longitudinal and widthwise central portions of the absorbent main body 10 and are fixed between the back sheet 13 and the cover sheet 18 in a state stretched in the longitudinal direction.

[0064] The above is a description of the basic structure of the pants-type diaper 1, but the structure of the pants-type diaper 1 is not limited to the above.

[0065] Regarding the absorbent main 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 stacked 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 portion of the upper core 31 and lower core 32. Fig. 8A is a schematic cross-sectional view taken along line I-I in Fig. 6, and Fig. 8B is a schematic cross-sectional view taken along line II-II in Fig. 6. Fig. 9A is a schematic perspective view of the core wrap sheet 39, and Fig. 9B is an explanatory diagram of a modified arrangement of the core wrap sheet 39. Figs. 10A, 10B, 11A, and 11B are explanatory diagrams of modified grooves 35 and 36.

[0066] The absorbent core 30 has a two-layer structure and includes an upper core 31 and a lower core 32 that is disposed on the non-skin side in the thickness direction of the upper core 31. The upper core 31 and the lower core 32 each include a liquid-absorbent fiber 33 (such as a pulp fiber or a cellulose-based absorbent fiber) and a superabsorbent polymer 34 (SAP).

[0067] The upper core 31 and the lower core 32 each have an hourglass shape in plan view, with the longitudinal center narrowed inward in the width direction. As shown in Figure 6, the lower core 32 is slightly larger than the upper core 31, and the upper core 31 is positioned within the outer periphery of the lower core 32.

[0068] The upper core 31 has grooves 35 (second grooves) recessed in a portion of the upper core 31 in the thickness direction, and has, as viewed in the thickness direction, a groove region A1 (second groove region) in which the grooves 35 are provided and a non-groove region A2 (second non-groove region) in which no grooves are provided. The grooves 35 have a length in the longitudinal direction of the diaper 1. In the upper core 31, a plurality of longitudinally extending grooves 35 are arranged at intervals in both the width direction and the longitudinal direction. In addition, the grooves 35 in the first embodiment are upper grooves recessed from the skin-side surface of the upper core 31 to the non-skin-side surface in the thickness direction.

[0069] The lower core 32 also has grooves 36 formed by recessing a portion of the lower core 32 in the thickness direction, and has a groove region A3 with the grooves 36 and a non-groove region A4 without the grooves 36 when viewed in the thickness direction. However, unlike the grooves 35 of the upper core 31, the grooves 36 of the lower core 32 are lower grooves recessed from the non-skin-facing side of the lower core 32 toward the skin-facing side in the thickness direction. The grooves 36 have a length in the longitudinal direction (predetermined direction) of the diaper 1. In the lower core 32, a plurality of grooves 36 extending in the longitudinal direction are spaced apart in both the width direction and the longitudinal direction.

[0070] The lower core 32 further 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 generally rectangular slit that is long in the longitudinal direction and is provided in the widthwise center of the crotch region of the diaper 1. The pair of side slits 38 are also generally rectangular slits that are long in the longitudinal direction and are provided on both widthwise outer sides of the central slit 37 and in positions that overlap at least a portion of the central slit 37 in the longitudinal direction. The central slit 37 is longer in the widthwise and longitudinal directions than the side slits 38. Furthermore, when viewed in the thickness direction, the entire central slit 37 overlaps with the upper core 31, but most of the side slits 38 do not overlap with the upper core 31.

[0071] The crotch region of the diaper 1 is the region that is expected to come into contact with the wearer's crotch area. Specifically, the crotch region is the region vertically below (inner in the longitudinal direction) the joint 2 of the diaper 1. Alternatively, the crotch region may be the central region when the diaper 1 (FIG. 2) in the unfolded and stretched state is divided into three longitudinal sections.

[0072] When the upper core 31 and the lower core 32 are each divided in half in the thickness direction, the portions located on the skin side are referred to as skin-side portions 311, 321, and the portions located on the non-skin side are referred to as non-skin-side portions 312, 322. Specifically, the non-groove regions A2, A4 are divided into the skin-side portions 311, 321 and the non-skin-side portions 312, 322 along an imaginary line extending horizontally from the center C in the thickness direction of the thickest portion.

[0073] 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, excreted liquid excreted on 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. Therefore, the excreted liquid is dispersed in the longitudinal direction along the groove region A1, which extends in the longitudinal direction.

[0074] In particular, the grooves 35 of the upper core 31 are upper grooves. Therefore, the skin-side portion 311 of the groove region A1 is a 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). Because the upper core 31 directly receives excreted liquid, by making the grooves 35 upper grooves, excreted liquid excreted on the skin-side portion of the upper core 31 can immediately fall into the space portion of the groove 35 and be dispersed in the longitudinal direction. Therefore, even when a large amount of excreted liquid is excreted, overflow of excreted liquid on the skin-side portion of the upper core 31 can be suppressed.

[0075] Furthermore, if the grooves 35 in the upper core 31 were slits that penetrated in the thickness direction, the excreted liquid would migrate downward along the groove region A1 before diffusing, resulting in spot absorption in a portion of the lower core 32. There is a limit to the range to which the excreted liquid can diffuse from the spot-absorbed portion, and the excreted liquid would not be absorbed over a wide area of ​​the lower core 32. The excreted liquid would also migrate to the lower core 32 before diffusing in the upper core 31, preventing the excreted liquid from being absorbed over a wide area of ​​the upper core 31.

[0076] In contrast, the grooves 35 of the upper core 31 of this embodiment are grooves 35 (recesses) formed by recessing a portion of the upper core 31 in the thickness direction, which prevents the excreted liquid from immediately migrating from the groove region A1 to the lower core 32, and allows the excreted liquid to be dispersed over a wide area of ​​the upper core 31 along the groove region A1.

[0077] 6, a groove region A1 is provided in a portion of the upper core 31 in the region where the upper core 31 and the lower core 32 overlap in the thickness direction. This allows the lower core 32 to receive and absorb excrement that has spread along the groove region A1 of the upper core 31. This allows the lower core 32 to also receive and absorb excrement, resulting in high excrement diffusibility in the lower core 32 and excrement being absorbed over a wide area of ​​the lower core 32. After the lower core 32 has saturated its absorption, the excrement is diffused and absorbed over a wide area of ​​the upper core 31.

[0078] The lower core 32 of this embodiment has a central slit 37. In this case, it is preferable to provide a groove region A1 in a portion of the upper core 31 that overlaps in the thickness direction with a portion of the lower core 32 where the central slit 37 is not located. This allows the lower core 32 to receive and absorb excrement that has spread along the groove region A1.

[0079] Furthermore, because the grooves 35 of the upper core 31 of this embodiment are different from slits, the lower core 32 is not exposed to the skin side in the groove region A1. This prevents excreted fluid absorbed in the portion of the lower core 32 facing the groove region A1 of the upper core 31 from rewetting and coming into contact with the skin. Furthermore, the skin-side portion 311 of the non-groove region A2 of the upper core 31 is a high SAP region. Therefore, excreted fluid absorbed by the skin-side portion 311 of the non-groove region A2 is firmly retained by the superabsorbent polymer 34. This prevents excreted fluid from rewetting onto the skin-side surface of the upper core 31.

[0080] As described above, the absorbent core 30 of this embodiment has high diffusibility of excreted liquid between the upper core 31 and the lower core 32, resulting in a high absorption capacity. Therefore, even in the case of repeated excretion, overflow and leakage of excreted liquid can be suppressed. Rewetting of excreted liquid can also be suppressed.

[0081] 7, the bottoms of the grooves 35 of the upper core 31 are located at the boundary between the skin-side portion 311 and the non-skin-side portion 312. However, this is not limited thereto, and the bottoms of the grooves 35 may be shallower or deeper than the boundary. Furthermore, the high SAP region of the skin-side portion 311 in the non-groove region A2 of the upper core 31 may extend further toward the non-skin side than the bottoms of the grooves 35 (or the ceilings of the grooves 35 if the grooves 35 are lower grooves). Furthermore, a portion of the non-skin-side portion 312 of the groove region A1 (i.e., a portion of the bottoms of the grooves 35 or a portion of the ceilings of the grooves 35) may be a high SAP region. When a portion of the bottoms (or ceilings) of the grooves 35 is a high SAP region, excreted liquid is less likely to be drawn into the bottoms (or ceilings) of the grooves 35. Therefore, excreted liquid is more likely to diffuse over the bottoms of the grooves 35 (or below the ceilings), improving the diffusibility of excreted liquid in the upper core 31. The same applies to the lower core 32 .

[0082] Furthermore, in the upper core 31, the average density of the superabsorbent polymer 34 in the non-skin side portion 312 of the non-groove region A2 is preferably lower than the average density of the superabsorbent polymer 34 in the skin side portion 311 of the non-groove region A2. This facilitates the downward migration of excreted liquid from the skin side portion 311 of the groove region A1 (to the non-skin side portion 312) to the non-skin side portion 312 of the non-groove region A2, which is a low SAP region. This enhances the diffusibility of excreted liquid in the upper core 31. For example, excreted liquid flows into the non-groove region A2, which is aligned widthwise with the groove region A1, and is diffused widthwise as well. The excreted liquid further diffused in the upper core 31 is then received by the lower core 32, allowing the excreted liquid to be absorbed over a wider area of ​​the lower core 32. However, this is not limited to the above, and 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 greater than the average density of the superabsorbent polymer 34 in the skin side portion 311 of the non-groove region A2.

[0083] Furthermore, 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 absorbed by the skin side portion 311 of the non-groove region A2. Because the skin side portion 311 of the non-groove region A2 is a high SAP region, the absorbed excreted liquid is firmly held by the superabsorbent polymer 34. This prevents excreted liquid from rewetting onto the skin side of the upper core 31.

[0084] Furthermore, when the grooves 35 of the upper core 31 are upper grooves, the superabsorbent polymer 34 and liquid-absorbent fibers are disposed 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.

[0085] This allows excreted liquid that has flowed into the groove region A1 (space) of the skin-side portion 311 of the upper core 31 to easily migrate to the non-skin-side portion 312 (below) of the groove region A1, which is a low SAP region. In other words, liquid permeability in the groove region A1 is improved. Therefore, even when excretion is repeated, the liquid permeability of the groove region A1 can be prevented from being hindered by the superabsorbent polymer 34 that has absorbed excreted liquid.

[0086] Furthermore, when the grooves 35 of the upper core 31 are upper grooves, it is preferable that the average density of the liquid-absorbent fibers in the non-skin side portions 312 of the non-groove region A2 be higher than the average density of the liquid-absorbent fibers in the non-skin side portions 312 of the groove region A1. This makes it easier for excreted liquid that has migrated to the non-skin side portions 312 of the groove region A1 to migrate to the non-skin side portions 312 of the non-groove region A2 by capillary action. This increases the diffusibility of excreted liquid in the upper core 31. The excreted liquid is then absorbed over a wider area of ​​the lower core 32, which receives the excreted liquid diffused in the upper core 31.

[0087] Furthermore, the upper core 31 and the lower core 32 of this embodiment each have a thin fiber layer 313, 323 on the skin-side surface. The fiber layer 313, 323 is composed of liquid-absorbent fiber 33 and does not contain superabsorbent polymer 34. The fiber layers 313, 323 facilitate the planar diffusion of excreted liquid on the skin-side surface of the upper core 31 and the skin-side surface of the lower core 32. This improves the diffusibility of excreted liquid in the upper core 31 and the lower core 32. However, one or both of the upper core 31 and the lower core 32 do not necessarily have to have the fiber layer 313, 323. The fiber layers 313, 323 are also thin. Therefore, the difference in average density of the superabsorbent polymer 34 between the skin side portions 311, 321 (areas including the fiber layers 313, 323) and the non-skin side portions 312, 322 (areas not including the fiber layers 313, 323) of the upper core 31 and the lower core 32 is not affected.

[0088] Furthermore, although not shown, a thin fiber layer (a layer of liquid-absorbent fiber 33 that does not contain superabsorbent polymer 34) may be provided on the non-skin side of upper core 31 and lower core 32. In this case, too, excreted liquid is more likely to be diffused in the planar direction on the non-skin side of upper core 31 and the non-skin side of lower core 32, further improving the diffusibility of excreted liquid in upper core 31 and lower core 32.

[0089] Comparison of the average density of the superabsorbent polymer 34 and the average density of the liquid-absorbent fibers 33 in various portions of the absorbent core 30 can be performed using well-known methods. For example, the absorbent core 30 to be measured is immersed in liquid nitrogen and frozen, then cut in the thickness direction with a razor to obtain a cross-section of the absorbent core 30 including the portions to be compared (e.g., the groove region A1 and the non-groove region A2). After the absorbent core 30 is returned to room temperature, a cross-sectional image is obtained at 50x magnification using an electron microscope (e.g., Keyence VE7800, etc.). Based on the cross-sectional image, the average density of the superabsorbent polymer 34 in the portions to be compared can be visually compared. Based on the cross-sectional image, the average density of the liquid-absorbent fibers 33 in the portions to be compared can also be visually compared. Alternatively, the number of superabsorbent polymers 34 or the number of liquid-absorbent fibers 33 per unit area in the cross-sectional image can be counted and compared.

[0090] Alternatively, for example, the absorbent core 30 to be measured may be frozen and then cut to obtain a cross section of the absorbent core 30 including a region to be compared. A method may be used in which the average density of the superabsorbent polymer 34 is compared based on an image obtained by irradiating the cross section with X-rays. The amount of X-ray penetration is reduced in areas where the superabsorbent polymer 34 overlaps greatly. Therefore, areas with a high average density of the superabsorbent polymer 34 appear darker in the X-ray image, allowing comparison based on the shade of the regions to be compared. Alternatively, the weight of the superabsorbent polymer 34 and the weight of the liquid-absorbent fiber 33 may be obtained using the measurement method described in Japanese Patent Application No. 2018-542962, and converted into density for comparison.

[0091] As described above, by configuring the absorbent core 30 in a two-layer structure, the amount of excreted liquid that can be absorbed by the diaper 1 can be increased. However, if excreted liquid does not easily migrate from the upper core 31 to the lower core 32, the excreted liquid may stagnate in the space at the boundary between the upper core 31 and the lower core 32 in the thickness direction. This reduces the amount of excreted liquid absorbed by the lower core 32, and the absorption performance of the lower core 32 cannot be effectively utilized.

[0092] Therefore, in the lower core 32, the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the groove region A3 should be lower than the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the non-groove region A4. Then, at least a portion of the groove region A3 of the lower core 32 should be provided in the region where the upper core 31 and the lower core 32 overlap in the thickness direction.

[0093] By doing so, excreted liquid that migrates to the boundary between the upper core 31 and the lower core 32 in the thickness direction is more easily absorbed by the groove region A3, which is a low SAP region, of the skin-side portion 321 of the lower core 32. This prevents excreted liquid from stagnating at the boundary between the upper core 31 and the lower core 32, allowing the excreted liquid to migrate to the lower core 32. This allows the lower core 32 to efficiently absorb excreted liquid, preventing a decrease in the amount of excreted liquid that the diaper 1 can absorb. 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, excreted liquid absorbed by the skin-side portion 321 of the non-groove region A4 is firmly retained by the superabsorbent polymer 34, preventing rewetting of the excreted liquid.

[0094] Furthermore, excreted liquid absorbed in the groove region A3 tends to migrate to the lower space (non-skin side portion 322). The excreted liquid is then dispersed in the longitudinal direction along the space in the groove region A3. Therefore, the excreted liquid dispersed in the upper core 31 is further dispersed in the lower core 32, and the excreted liquid is absorbed over a wider area of ​​the lower core 32.

[0095] Furthermore, the grooves 36 of the lower core 32 are grooves 36 (recesses) formed by recessing a portion of the lower core 32 in the thickness direction. Therefore, unlike when the grooves 36 are slits that penetrate the lower core 32 in the thickness direction, excreted liquid is prevented from stagnating in the grooves 36. In other words, excreted liquid can be diffused even in the areas where the liquid-absorbent fibers 33 and superabsorbent polymers 34 are arranged.

[0096] Furthermore, when the grooves 36 of the lower core 32 are lower grooves, liquid permeability to the lower part (space) in the groove region A3 is high. Therefore, excreted liquid can be drawn into the non-skin-side portion 322 of the lower core 32 and then diffused, allowing the lower core 32 to be used effectively. Furthermore, since the grooves 36 of the lower core 32 are lower grooves rather than slits and there are no spaces (recesses) of the grooves 36 on the skin-side surface of the lower core 32, the migration rate of excreted liquid from the upper core 31 to the lower core 32 can be appropriately suppressed. Therefore, excreted liquid is diffused in the upper core 31 before migrating to the lower core 32.

[0097] Furthermore, as with the upper core 31, it is preferable that in the lower core 32, 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.

[0098] By doing so, excreted liquid that has been diffused in the longitudinal direction along the spaces of the grooves 36 in the non-skin side portion 321 of the lower core 32 is more likely to migrate to the non-skin side portion 322 of the non-groove region A4, which is a low SAP region. This further improves the diffusibility of excreted liquid in the lower core 32. Furthermore, excreted liquid that has migrated to the non-skin side portion 322 of the non-groove region A4 is absorbed by the skin side portion 321 of the non-groove region A4. Because the skin side portion 321 of the non-groove region A4 is a high SAP region, the absorbed excreted liquid is firmly retained, preventing rewetting of the excreted liquid.

[0099] Furthermore, the planar shape of the lower core 32 is slightly larger than that of the upper core 31, and the lower core 32 extends longitudinally outward beyond the longitudinal end 31a of the upper core 31. In the portion of the lower core 32 that extends longitudinally outward beyond the upper core 31, excreted fluid does not stagnate at the boundary with the upper core 31, but it is preferable to provide a groove region A3 of the lower core 32 in this portion as well.

[0100] This allows excreted fluid to be diffused to the area of ​​the lower core 32 that does not overlap with the upper core 31 in the thickness direction. Furthermore, the longitudinal ends of the lower core 32 are made flexible and easily deformable by the grooves 36. This allows the lower core 32 to fit easily around the lower abdomen and buttocks of the wearer.

[0101] Furthermore, when viewed in the thickness direction, it is preferable that the groove region A3 of the lower core 32 has a portion that overlaps with the groove region A1 of the upper core 31. In the first embodiment, most of the grooves 35 of the upper core 31 (except for the two grooves 35A that overlap with the central slit 37) overlap with the grooves 36 of the lower core 32.

[0102] In the upper core 31, a larger amount of excreted fluid flows downward (toward the skin side) through the groove region A1 than through the non-groove region A2. Therefore, when the groove region A1 of the upper core 31 and the groove region A3 of the lower core 32 are aligned, much of the excreted fluid that passes through the groove region A1 of the upper core 31 is received by the groove region A3 of the lower core 32 and drawn into the interior of the lower core 32 (the space in the non-skin side portion 322) and diffused. This further reduces stagnation of excreted fluid at the boundary between the upper core 31 and the lower core 32. In this embodiment, the groove 35 of the upper core 31 and the overlapping groove 36 of the lower core 32 have the same shape and are positioned in the same way, but this is not limited to this and they may simply overlap at least partially.

[0103] Furthermore, in at least a portion 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 312 of a region of the upper core 31 facing the certain region. This makes it possible to appropriately suppress the migration rate of excreted liquid from the upper core 31 to the lower core 32. Therefore, the excreted liquid is diffused in the upper core 31 before migrating to the lower core 32.

[0104] Specifically, in the absorbent core 30 of the first embodiment, a large portion of the groove region A1 of the upper core 31 overlaps with a groove region A3 of the lower core 32, and a large portion of the non-groove region A2 of the upper core 31 overlaps with a 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 opposing non-groove region A2 of the non-skin-side portion 312 of the upper core 31 is a low SAP region, resulting in the above-mentioned relationship. On the other hand, the groove region A3 of the skin-side portion 321 of the lower core 32 and the opposing groove region A1 of the non-skin-side portion 312 of the upper core 31 are both low SAP regions. Therefore, it is preferable to make the average density of the superabsorbent polymer 34 higher in the groove region A3 of the skin-side portion 321 of the lower core 32 than in the groove region A1 of the non-skin-side portion 312 of the upper core 31.

[0105] The lower core 32 also has a central slit 37 extending in the longitudinal direction at the widthwise central portion of the region that comes into contact with the wearer's crotch region. Therefore, the lower core 32 and the upper core 31 that overlaps it bend (longitudinal direction) along the central slit 37. As a result, the widthwise central portion of the absorbent core 30 deforms so as to be convex toward the skin relative to the sides, making it easier to fit around the wearer's crotch region.

[0106] Furthermore, when viewed in the thickness direction, the groove region A1 of the upper core 31 has a portion overlapping with the central slit 37 (groove 35A in FIG. 6 ). Although the absorbent core 30 has a reduced ability to absorb excreted liquid in the portion where the central slit 37 is located, the groove region A1 of the upper core 31 that overlaps with the central slit 37 can diffuse the excreted liquid. 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 beyond the central slit 37. This allows excreted liquid to migrate to portions that do not overlap with the central slit 37. This prevents excreted liquid from overflowing in the crotch region.

[0107] However, this is not limited to the above. The portion of the absorbent core 30 where the central slit 37 is located has reduced rigidity. Therefore, when viewed in the thickness direction, at least a portion of the central slit 37 of the lower core 32 may not overlap the groove region A1 (groove 35) of the upper core 31. For example, as shown in a modified example in FIG. 10A , the entire area of ​​the central slit 37 may not overlap the groove region A1 of the upper core 31. This prevents the portion of the absorbent core 30, whose rigidity has been reduced by the central slit 37, from being further reduced by the groove region A1, thereby preventing the absorbent core 30 from losing its shape. This allows the absorbent core 30 to maintain its absorption performance for a long period of time. Furthermore, excreted liquid is likely to accumulate in the central slit 37. Therefore, by making the region of the upper core 31 overlapping the central slit 37 a non-groove region A2, the skin-side portion 311 becomes a high-SAP region, thereby preventing excreted liquid from migrating to the central slit 37. Therefore, accumulation of liquid in the central slit 37 can be suppressed.

[0108] It is also preferable that the grooves 35 of the upper core 31 do not extend to the outer periphery of the upper core 31, and the grooves 36 of the lower core 32 do not extend to the outer periphery of the lower core 32. This can prevent the upper core 31 and the lower core 32 from losing their shape. It can also prevent excreted fluid from diffusing to the outer periphery of the upper core 31 and the lower core 32.

[0109] As described above, the diaper 1 has longitudinally stretchable crotch elastic members 17 disposed in the region that contacts the crotch portion of the wearer. As shown in Fig. 6, it is preferable that the central slit 37 and the groove region A1 of the upper core 31 overlap with the crotch elastic members 17 in the thickness direction.

[0110] As a result, the deformation of the absorbent core 30, which becomes convex toward the skin side due to the central slit 37, is promoted by the stretching of the crotch elastic members 17. Furthermore, the groove regions A1 make the absorbent core 30 flexible, making it easier to deform to fit the crotch area of ​​the wearer. This deformation is also promoted by the stretching of the crotch elastic members 17. As a result, the diaper 1 fits the wearer better.

[0111] 10A, even when the entire area of ​​the central slit 37 of the lower core 32 does not overlap with the groove area A1 of the upper core 31, it is preferable that the central slit 37 has a portion that overlaps with the crotch elastic member 17 when viewed in the thickness direction. In this way, the deformation of the absorbent core 30 by the central slit 37, which causes the absorbent core 30 to become convex toward the skin, is promoted by the crotch elastic member 17, and the portion of the lower core 31 where the central slit 37 is folded makes it difficult for excreted fluid to stagnate.

[0112] Furthermore, in the longitudinal portion overlapping with the central slit 37 of the lower core 32, the widthwise side edges of the upper core 31 are located widthwise outward of the central slit 37 and widthwise inward of the widthwise side edges of the lower core 32. Therefore, the widthwise side edges of the lower core 32 tend to bend (longitudinally) along the widthwise side edges of the upper core 31. In other words, the widthwise side edges of the lower core 32 tend to rise up toward the skin.

[0113] The lower core 32 also has a pair of side slits 38 on either side of the central slit 37 in the width direction. The widthwise positions of the side slits 38 are approximately the same as the widthwise side edges of the upper core 31. Therefore, the pair of side slits 38 also make it easy for the widthwise side portions of the lower core 32 to rise up toward the skin. Therefore, in the crotch region, the absorbent core 30 is prone to deforming, with the widthwise central portion deforming convexly toward the skin and the widthwise side portions rising up toward the skin, forming a W-shaped cross section. This allows for a better fit around the crotch area of ​​the wearer.

[0114] It is preferable that at least one of grooves 35 in upper core 31 and grooves 36 in lower core 32 be provided in the region where upper core 31 and lower core 32 overlap, outside central slit 37 of lower core 32 in the width direction. By doing so, the highly rigid region where the two core layers 31 and 32 overlap is made flexible by grooves 35 and 36, making it easier to deform and fit the crotch area of ​​the wearer.

[0115] Additionally, it is preferable that groove region A3 (groove 36A) of lower core 32 be provided widthwise outboard of side slits 38 of lower core 32, in a position that overlaps at least a portion of side slit 38 in the longitudinal direction. This increases the flexibility of the widthwise side portions of lower core 32 that rise toward the skin. This allows the widthwise side portions of lower core 32 to more easily deform along the base of the wearer's legs, improving fit.

[0116] However, the present invention is not limited to the above, and the lower core 31 may have a configuration that does not include either or both of the central slit 37 and the side slits 38 .

[0117] Furthermore, it is preferable that the grooves 36 of the lower core 32 are disposed away from the outer peripheral edges of the central slit 37 and the side slits 38. This can prevent the lower core 32 from losing its shape.

[0118] The widths (widthwise lengths) of the central slit 37 and the side slits 38 are preferably larger than the widths of the grooves 35 of the upper core 31 and the grooves 36 of the lower core 32 (widthwise lengths of the main grooves 351, 361, and longitudinal lengths of the minor grooves 352, 362). This allows the absorbent core 30 to easily deform into a W-shape due to the central slit 37 and the side slits 38. On the other hand, by not making the widths of the grooves 35, 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, for example, approximately 7 mm to 50 mm so as not to excessively reduce absorption performance. The widths of the grooves 35, 36 are preferably, for example, approximately 1 mm to 8 mm. The longitudinal lengths of the central slit 37 and the side slits 38 are preferably such that they abut against the wearer's crotch region, and are, for example, approximately 50 to 300 mm, preferably approximately 100 to 250 mm.

[0119] The groove 35 of the upper core 31 and the groove 36 of the lower core 32 each have a main groove 351, 361 having a length in the longitudinal direction, and a minor groove 352, 362 extending in the width direction from the main groove 351, 361. Specifically, a plurality of minor grooves 352, 362 extend in the width direction from the main groove 351, 361 at intervals in the longitudinal direction. A plurality of such main grooves 351, 361 are lined up at intervals in the width direction and longitudinal direction.

[0120] The minor grooves 352, 362 allow excreted fluid excreted on the skin-side surface of the upper core 31 and excreted fluid drawn into the non-skin-side portion 322 (space portion) of the lower core 32 to be diffused not only in the longitudinal direction but also in the width direction. This further improves the diffusibility of excreted fluid in the upper core 31 and the lower core 32.

[0121] Furthermore, by making the absorbent core 30 a two-layer structure, the absorbent core 30 is able to absorb more excrement while also becoming more rigid and less likely to deform. However, the upper core 31 and the lower core 32 of this embodiment have grooves 35, 36. In particular, the grooves 35, 36 are provided in the area where the upper core 31 and the lower core 32 overlap, increasing the rigidity. This gives the absorbent core 30 flexibility and allows it to easily deform along the wearer's body.

[0122] Furthermore, the grooves 35, 36 have not only main grooves 351, 361 along the longitudinal direction but also minor grooves 352, 362 along the width direction. Therefore, the upper core 31 and the lower core 32 are easily bent not only along the longitudinal direction but also along the width direction starting from the minor grooves 352, 362. Therefore, the absorbent core 30 is easily curved in the longitudinal direction along the region from the lower abdomen to the buttocks of the wearer.

[0123] Furthermore, in the first embodiment, most of the grooves 35 of the upper core 31 overlap with the grooves 36 of the lower core 32. 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 minor grooves 352 of the upper core 31 and the minor grooves 362 of the lower core 32 also overlap. Therefore, the overlapping regions of the upper core 31 and the lower core 32 are more likely to bend in the longitudinal and width directions along the grooves 35, 36, and are more likely to deform to fit the wearer's body.

[0124] Furthermore, the longitudinal positions of the minor grooves 352, 362 adjacent to each other in the width direction are aligned, so that the upper core 31 and the lower core 32 are easily bent in the width direction starting from the minor grooves 352, 362, and are easily deformed to fit the wearer's body.

[0125] As shown in FIG. 6 , the upper core 31 and the lower core 32 have regions A21, A41, and A42, respectively, longitudinally rearward of the central slit 37, where the non-groove regions A2 and A4 are continuous from one end to the other in the width direction. 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, respectively, the upper core 31 and the lower core 32 are more likely to bend longitudinally along those regions (starting from the longitudinal ends of the grooves 35 and 36). In other words, the longitudinally extending grooves 35 and 36 are less likely to impede the longitudinal folding of the upper core 31 and the lower core 32. Therefore, the rear ends of the upper core 31 and the lower core 32 are more likely to conform to the rounded buttocks of the wearer.

[0126] 6, the rear end 32a of the lower core 32 is located further rearward than the rear end 31a of the upper core 31, and the rear end 31a of the upper core 31 is located in a non-groove region A42 that is continuous in the width direction of the lower core 32. Therefore, the rear end of the lower core 32 is likely to bend in the longitudinal direction along the rear end 32a of the upper core 31. This allows the rear end of the lower core 32 to easily fit around the rounded buttocks of the wearer.

[0127] Furthermore, since the rear end portion of the absorbent core 30 is easily bent in the longitudinal direction as described above, it is possible to prevent the W-shaped deformation (deformation caused by the central slit 37 and the side slits 38) in the crotch region of the absorbent core 30 from being transmitted to the rear of the absorbent core 30. Therefore, the rear end portion of the absorbent core 30 is more likely to fit the buttocks of the wearer.

[0128] Furthermore, in the thickness direction, the region where the upper core 31 and the lower core 32 do not overlap (the region where only the lower core 32 is present) has low rigidity and high flexibility. Therefore, although not shown, the width of the grooves 36 of the lower core 32 (specifically, the widthwise length of the main groove 361 and the longitudinal length of the minor groove 362) may be narrower in the region where only the lower core 32 is present than in the region where the upper core 31 and the lower core 32 overlap. This can prevent the lower core 32 from losing its shape.

[0129] Furthermore, in the thickness direction, the boundary between the overlapping and non-overlapping regions of the upper core 31 and the lower core 32 (the outer peripheral edge of the upper core 31) is likely to be a folding point of the absorbent core 30, but it is also likely to be a starting point for deformation of the absorbent core 30. Therefore, it is preferable not to provide groove regions A1 and A3 at the boundary, and it is particularly preferable not to provide groove region A3 of the lower core 32. This can prevent the absorbent core 30 from losing its shape.

[0130] As shown in Figures 8A and 8B, a core wrap sheet 39, which is a liquid-permeable sheet (e.g., tissue, nonwoven fabric, etc.), may be provided at the boundary between the upper core 31 and the lower core 32. As shown in Figure 9A, the core wrap sheet 39 may be, for example, a textured nonwoven fabric having longitudinally extending convex portions 391 and concave portions 392. The textured core wrap sheet 39 can diffuse excreted liquid in the longitudinal direction, improving the diffusibility of excreted liquid in the upper core 31 and the lower core 32. Note that the textured core wrap sheet 39 may not necessarily extend longitudinally, but may also extend widthwise or in other directions. Furthermore, the textured core wrap sheet 39 increases the storage space for excreted liquid. Therefore, even when a large amount of excreted liquid is excreted, the storage space of the core wrap sheet 39 can temporarily store the excreted liquid, thereby preventing the excreted liquid from overflowing from the skin-side surface of the upper core 31. Although not shown, the core wrap sheet 39 may have longitudinally extending convex portions 391 and concave portions 392 arranged intermittently in the longitudinal direction. In this case, excreted liquid can also be diffused in the width direction at the intermittent portions of the concave and convex portions.

[0131] Furthermore, by arranging the core wrap sheet 39 at the boundary between the upper core 31 and the lower core 32 (by facing the uneven surface of the core wrap sheet 39 to the non-skin side of the upper core 31), excreted liquid can be more diffused on the non-skin side of the upper core 31. However, the core wrap sheet 39 is not limited to a sheet having unevenness.

[0132] Furthermore, the core wrap sheet 39 need not necessarily be 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 wrap around the lower core 32 from the non-skin side toward the skin side. This prevents the lower core 32 from losing its shape. The core wrap sheet 39 may also be disposed in a region other than the boundary between the upper core 31 and the lower core 32 (e.g., a region of the lower core 32 excluding regions p1 and p2 in FIG. 9B ). This eliminates the adhesive that bonds the core wrap sheet 39 to the absorbent core 30 at the boundary between the upper core 31 and the lower core 32, improving liquid permeability from the upper core 31 to the lower core 32. The core wrap sheet 39 may also be disposed in the opposite direction to that shown in FIG. 9B , wrapping around the lower core 32 from the skin side toward the non-skin side. In this case, when the lower core 32 is completely rolled up, the core wrap sheet 39 overlaps, but because the overlapping area is positioned on the non-skin side of the lower core 32, liquid transfer from the upper core 31 to the lower core 32 is smoother than when the core wrap sheet 39 is positioned between the upper core 31 and the lower core 32, and pooling of excreted liquid can be suppressed. Alternatively, the core wrap sheet 39 may be positioned on part of or around the upper core 31, or the core wrap sheet 39 may not be positioned on the absorbent core 30.

[0133] Furthermore, the shape, number, and arrangement 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 Figures 4 to 6. For example, in the absorbent core 30 shown in Figure 10B, the grooves 35B, 36B provided on the widthwise sides of the front end of the upper core 31 are inclined widthwise inward toward the longitudinal center. Therefore, the front end of the absorbent core 30, which rises from the narrowest part of the lower core 32, is easily deformed into an inverted triangular cup shape to encase the wearer's lower abdomen, improving the fit of the diaper 1.

[0134] 11A , for example, minor grooves 352, 362 extend from the major grooves 351, 361 in the longitudinal center of the absorbent core 30, but minor grooves 352, 362 are not provided at the longitudinal ends of the absorbent core 30. The longitudinal ends of the lower core 32 form non-groove regions A4. In this way, the area ratios of the groove regions A1, A3 may be smaller at the longitudinal ends of the upper core 31 and the lower core 32 than at the central portions. This can prevent the absorbent core 30 from losing its shape.

[0135] 11B, the grooves 35, 36 may extend all the way to both longitudinal ends of the upper core 31 and the lower core 32. This allows excrement to be diffused over a long distance in the longitudinal direction. In this case, non-groove regions A22, A43 may be provided rearward of the central slit 37 so that the rear end of the absorbent core 30 fits along the buttocks of the wearer (FIG. 11B). Alternatively, although not shown, the grooves 35, 36 may extend continuously from the front end to the rear end of the upper core 31 and the lower core 32 in the longitudinal direction.

[0136] Additionally, the grooves 35 of the upper core 31 and the grooves 36 of the lower core 32 are not limited to having a predetermined length in the longitudinal direction, and may extend in another direction, such as the width direction. The grooves 35 of the upper core 31 and the grooves 36 of the lower core 32 may extend in different directions. The grooves 35 of the upper core 31 and the grooves 36 of the lower core 32 may not overlap at all in the thickness direction. The grooves 35 of the upper core 31 and the grooves 36 of the lower core 32 may not have the minor grooves 352, 362. Groove regions A1, A3 may not be provided in the regions where the upper core 31 and the lower core 32 do not overlap in the thickness direction.

[0137] <<Second Embodiment>> Figure 12 is a cross-sectional schematic diagram of an absorbent core 30 in a second embodiment. The lower core 32 in the second embodiment is the same as the lower core 32 in the first embodiment. Furthermore, the upper core 31 in the second embodiment has a groove 35 (upper groove) recessed from the skin-side to the non-skin-side, similar to the upper core 31 in the first embodiment. However, in the second embodiment, the superabsorbent polymer 34 is evenly distributed throughout the entire upper core 31 (excluding the fiber layer 313). In other words, the difference in average density of the superabsorbent polymer 34 in each portion of the upper core 31 is the same and is smaller than the difference in average density of the superabsorbent polymer 34 in each portion of the lower core 32 (for example, the groove region A3 and non-groove region A4 of the skin-side portion 321).

[0138] In this case, excreted liquid excreted on the skin-side surface of the upper core 31 can be immediately dropped into the spaces of the grooves 35 of the upper core 31 and diffused in the longitudinal direction. Furthermore, because the superabsorbent polymer 34 is evenly distributed in the upper core 31, even with repeated excretion, the migration of excreted liquid is less likely to be hindered by the superabsorbent polymer 34 that has absorbed it, and the upper core 31 has good liquid permeability. Therefore, excreted liquid is diffused in the upper core 31 and then migrates to the boundary between the upper core 31 and the lower core 32 in the thickness direction. The excreted liquid that migrates to the boundary is drawn in by the groove region A3 (low SAP region) of the skin-side portion 321 of the lower core 32, and then further diffused by the groove region A3 (space portion) of the non-skin-side portion 322.

[0139] When the upper core 31 having the superabsorbent polymer 34 evenly distributed in this manner has grooves 35, the grooves 35 may be upper grooves as shown in Fig. 12 or lower grooves (not shown). In the case of lower grooves, excreted liquid that passes through the groove region A1 of the upper core 31 and migrates to the non-skin side portion 312 can also be diffused by the spaces in the grooves 35.

[0140] <<Third Embodiment>> Figure 13 is a cross-sectional schematic diagram of an absorbent core 30 in a third embodiment. The lower core 32 in the third embodiment is the same as the lower core 32 in the first embodiment. Furthermore, the upper core 31 in the third embodiment does not have grooves 35, and the superabsorbent polymer 34 is evenly distributed throughout the entire upper core 31 (excluding the fiber layer 313).

[0141] In this case, excreted liquid excreted on the skin-side surface of the upper core 31 is taken into the upper core 31, diffuses in the planar direction, and migrates to the boundary between the upper core 31 and the lower core 32 in the thickness direction. When a fiber layer 313 is provided on the skin-side surface of the upper core 31, excreted liquid is diffused in the planar direction at the skin-side surface of the upper core 31. Furthermore, because the superabsorbent polymer 34 is evenly distributed in the upper core 31, even with repeated excretion, liquid migration is less likely to be hindered by the superabsorbent polymer 34 that has absorbed the excreted liquid, resulting in good liquid permeability of the upper core 31. Excreted liquid that migrates to the boundary between the upper core 31 and the lower core 32 is drawn inside by the groove region A3 (low SAP region) of the skin-side portion 321 of the lower core 32, and then diffused by the groove region A3 (space portion) of the non-skin-side portion 322.

[0142] <<Fourth Embodiment>> Figures 14A and 14B are cross-sectional schematic diagrams of an absorbent core 30 in a fourth embodiment. The grooves 36 of the lower core 32 in the fourth embodiment are upper grooves, unlike the lower core 32 in the first embodiment. In this case, the groove region A3 in the skin-side portion 321 of the lower core 32 is a void, and the average density of the superabsorbent polymer 34 is lower than that in the non-groove region A4. The excreted liquid that passes through the upper core 31 falls into the voids of the grooves 36 in the skin-side portion 321 of the lower core 32 and is diffused in the longitudinal direction. This prevents excreted liquid from stagnating at the boundary between the upper core 31 and the lower core 32 in the thickness direction. Furthermore, the diffusibility of excreted liquid in the lower core 32 can be improved.

[0143] Furthermore, when the grooves 36 of the lower core 32 are upper grooves, similar to the upper core 31 of the first embodiment, the average density of the superabsorbent polymer 34 in the non-skin side portion 322 of the groove region A3 may be lower than the average density of the superabsorbent polymer 34 in the skin side portion 321 of the non-groove region A4. This prevents the superabsorbent polymer 34 that has absorbed excreted liquid from impairing the liquid permeability of the groove region A3 of the lower core 32. Furthermore, the average density of the liquid-absorbent fiber 33 in the non-skin side portion 322 of the non-groove region A4 of the lower core 32 may be higher than the average density of the liquid-absorbent fiber 33 in the non-skin side portion 322 of the groove region A3. This allows excreted liquid that has migrated to the non-skin side portion 322 of the groove region A3 to more easily migrate to the non-skin side portion 322 of the non-groove region A4 due to capillary action, further improving the diffusibility of excreted liquid in the lower core 32.

[0144] Even when the groove 36 of the lower core 32 is an upper groove, the groove 35 of the upper core 31 may be an upper groove (FIG. 14A) or a lower groove (FIG. 14B), or may be the upper core 31 described in the second or third embodiment.

[0145] 14B , by aligning the groove 35 (lower groove) of the upper core 31 and the groove 36 (upper groove) of the lower core 32, the space available for temporarily storing excreted fluid that has passed through the skin-side portion 311 of the upper core 31 is increased, and the stored excreted fluid can be dispersed along the grooves 35, 36. Therefore, even when a large amount of excreted fluid is excreted, the excreted fluid can be prevented from overflowing on the skin-side surface of the upper core 31.

[0146] Furthermore, when the grooves 35 of the upper core 31 are lower grooves, the upper core 31 is more likely to deform so that the center portion in the width direction is convex toward the skin compared to the side portions. This promotes deformation by the central slit 37 of the lower core 32, making it easier for the absorbent core 30 to fit around the wearer's crotch area. Conversely, when the grooves 36 of the lower core 32 are upper grooves, the lower core 32 is more likely to deform so that the center portion in the width direction is convex toward the non-skin side compared to the side portions. This makes it easier for the lower core 32 to deform to fit the rounded buttocks.

[0147] <<Fifth Embodiment>> Fig. 15 is a schematic plan view of a diaper 1 according to a fifth embodiment in an unfolded and stretched 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 stacked upper core 31 and lower core 32, as viewed from the non-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 non-skin side in the thickness direction. Fig. 19 is a plan view of an absorbent core 30 according to a modification of the fifth embodiment, as viewed from the non-skin side in the thickness direction.

[0148] 16, the lower core 32 of the fifth embodiment has a groove 36 (lower groove) recessed from the non-skin side surface of the lower core 32 toward the skin side in the thickness direction, but does not have a central slit 37 or a pair of side slits 38. The upper core 31 does not have a groove recessed in a portion of the upper core 31. However, this is not limited to the above, and slits (e.g., side slits 38) may be provided in areas of the lower core 32 where the groove area A3 is not provided.

[0149] 17, the absorbent core 30 has a "widthwise center portion" and a pair of "widthwise side portions" that are defined by dividing the maximum width of the absorbent core 30 into thirds (equal parts) in the width direction. The absorbent core 30 also has a "front portion 30F" located longitudinally forward of the product center line CL, and a "rear portion 30B" located longitudinally rearward of the product center line CL.

[0150] The product center line CL (center line) is a line that bisects (divides in equal parts) the diaper 1 (FIG. 15) in the unfolded and stretched state in the longitudinal direction. The longitudinal center of the absorbent core 30 does not necessarily have to coincide with the product center line CL, but may be offset from it. That is, the absorbent core 30 may be positioned offset toward the front or rear of the diaper 1. In this case, the longitudinal lengths of the front portion 30F and the rear portion 30B are different.

[0151] The rear portion 30B of the absorbent core 30 has regions that are obtained by dividing its maximum length (the length from the product centerline CL to the rearmost end of the absorbent core 30) into thirds (equally divided into three) in the longitudinal direction. The central region is referred to as the "rear first region 30B1," the region in front of the rear first region 30B1 is referred to as the "rear second region 30B2," and the region behind the rear first region 30B1 is referred to as the "rear third region 30B3."

[0152] Similarly, the front portion 30F of the absorbent core 30 has regions obtained by dividing its maximum length (the length from the product centerline CL to the front end of the absorbent core 30) into thirds (equally divided into three) in the longitudinal direction. The central region is referred to as the "front first region 30F1," the region behind the front first region 30F1 is referred to as the "front second region 30F2," and the region forward of the front first region 30F1 is referred to as the "front third region 30F3."

[0153] In other words, in the following description, the rectangular area defined by the maximum width and maximum length of the absorbent core 10 is divided into a front area and a rear area in the longitudinal direction, with the product center line CL as the boundary. The front area and the rear area are each divided into nine areas, and the absorbent core 30 is also divided accordingly.

[0154] Although the fifth embodiment uses a pants-type diaper 1 as an example of an absorbent article, the absorbent article of the fifth embodiment can also be applied to other absorbent articles such as tape-type diapers, absorbent pads, etc. When applied to tape-type diapers or absorbent pads, the product center line is identified when the absorbent article is deployed in the longitudinal direction, and the absorbent core is partitioned as shown in Fig. 17 .

[0155] As described in the first embodiment, the average density of the superabsorbent polymer 34 is lower in the skin-side portion of the groove region A3 of the lower core 32 than in the skin-side portion of the non-groove region A4. Therefore, excreted liquid passing through the upper core 31 is easily absorbed from the groove region A3, which is a low SAP region, into the lower core 32 and diffuses along the voids in the groove region A3. This prevents excreted liquid from stagnating at the boundary between the upper core 31 and the lower core 32. The smooth transition of excreted liquid from the upper core 31 to the lower core 32 prevents the upper core 31 from being unable to absorb all of the excreted liquid, resulting in overflow and leakage from the surface of the diaper 1. Diffusing excreted liquid also allows the lower core 32 to be effectively utilized over a wider area in the planar direction.

[0156] In particular, when the grooves 36 of the lower core 32 are lower grooves, the fluid permeability downward (to the space) in the groove region A3 is high, allowing excreted fluid to be drawn into the non-skin side of the lower core 32 and then diffused, thereby making effective use of the lower core 32. However, the grooves 36 of the lower core 32 of the fourth embodiment may be upper grooves, in which case excreted fluid that has passed through the upper core 31 falls into the space of the grooves 36 and diffuses therein, while the excreted fluid can be absorbed into the lower core 32 from the three surfaces that form the grooves 36 (the bottom surface and one pair of side surfaces), thereby preventing excreted fluid from stagnating at the boundary between the upper core 31 and the lower core 32.

[0157] Furthermore, similar to the absorbent core 30 shown in FIG. 7 of the first embodiment, the grooves 36 of the lower core 32 are not grooves compressed in the thickness direction, and the basis weight (g / m) of the lower core 32 (liquid-absorbent fiber 33 and superabsorbent polymer 34) is higher in the groove region A3 than in the non-groove region A4. ２By doing so, the excreted liquid that has passed through the upper core 31 can more easily flow into the groove region A3 and be more easily absorbed into the lower core 32 from the groove region A3.

[0158] The basis weight (g / m) of the lower core 32 in the grooved area A3 and the non-groove area A4 ２ The comparison of the material amounts in the grooved and non-groove regions A3 and A4 can be confirmed by a known method. For example, the lower core 32 is immersed in liquid nitrogen and frozen, and then cut in the thickness direction with a razor to obtain a cross section of the lower core 32 including the areas to be compared (groove region A3 and non-groove region A4). After the lower core 32 is returned to room temperature, the cross section image is observed using an electron microscope, and the amounts of material in the grooved and non-groove regions A3 and A4 can be compared visually or by counting the number of materials.

[0159] The lower core 32 (absorbent core 30) having a lower basis weight in the groove region A3 than in the non-groove region A4 can be manufactured, for example, by stacking the material for the lower core 32 on a pattern plate having protrusions on its bottom surface corresponding to the groove region A3. The basis weight and average density of the material can be controlled by controlling the amount of material (liquid-absorbent fiber 33 and superabsorbent polymer 34) supplied to the pattern plate.

[0160] As described above, excreted liquid that has passed through the upper core 31 is easily absorbed into the lower core 32 through the groove region A3 of the lower core 32. However, the absorbent core 30 is often thinner and has a lower basis weight in the region where the groove region A3 is located, which makes it more likely to rewet onto the surface of the diaper 1. Furthermore, since the skin-side portion 321 of the lower core 32 of this embodiment is a low SAP region, rewetting from the lower core 32 to the upper core 31 is more likely to occur, which may lead to rewetting onto the surface of the diaper 1.

[0161] Therefore, in the absorbent core 30 of the fifth embodiment, the area of ​​the groove region A3 of the lower core 32 located in the widthwise center of the rear first region 30B1 divided by the area of ​​the widthwise center of the rear first region 30B1 is smaller than the area of ​​the groove region A3 of the lower core 32 located in the widthwise center of the front first region 30F1 divided by the area of ​​the widthwise center of the front first region 30F1. Specifically, as shown in Fig. 17, only one main groove 361 having a length greater in the longitudinal direction than in the widthwise direction is provided in the widthwise center of the rear first region 30B1, whereas four main grooves 361 are provided in the widthwise center of the front first region 30F1.

[0162] The widthwise center of the rear first region 30B1 of the absorbent core 30 is a region that is likely to be subjected to body pressure when the wearer is sitting or lying on their back. Therefore, by reducing the area ratio of the grooves 36 in the widthwise center of the rear first region 30B1, the amount of excrement rewetting from the groove region A3 can be reduced even when strong body pressure is applied to the rear first region 30B1.

[0163] In contrast, the front portion 30F of the absorbent core 30 is a region that comes into contact with the wearer's excretory opening and through which excreted fluid is more easily excreted than the rear portion 30B, and is less susceptible to body pressure when the wearer is seated, etc. In particular, the front first region 30F1 between the front second region 30F2, which comes into contact with the wearer's crotch region, and the front third region 30F3, which is more likely to fit closely to the wearer due to the waist elastic members 211, 221 of the diaper 1, is less susceptible to body pressure from the wearer. Therefore, by increasing the area ratio of the grooves 36 in the widthwise central portion of the front first region 30F1, most excreted fluid from the wearer is less likely to stagnate at the boundary between the upper core 31 and the lower core 32 after passing through the upper core 31, and is quickly drawn into the lower core 32 from the groove region A3. In particular, when the wearer is a man, the front first region 30F1 is more likely to come into contact with the wearer's excretory opening, which more effectively absorbs the excretory liquid into the lower core 32. As a result, the upper core 31 is less likely to be able to absorb all the excretory liquid, which can then leak out from the surface of the diaper 1. Furthermore, the widthwise center of the front first region 30F1 is less likely to be subjected to body pressure, which also reduces the likelihood of rewetting.

[0164] The average basis weight (g / m ２ ) is the average basis weight (g / m ２ ) is preferably higher than the average basis weight of the upper core 31. In this case, the water absorption and retention capacity of the upper core 31 becomes relatively small. Therefore, by increasing the area ratio of the grooves 36 in the widthwise central portion of the front first region 30F1 as described above, a large amount of excreted liquid excreted from the excretion opening can be quickly transferred from the upper core 31 to the inside of the lower core 32. Therefore, even if the average basis weight of the upper core 31 is low, leakage of excreted liquid due to the upper core 31 being unable to absorb all of the excreted liquid can be effectively prevented.

[0165] However, the average basis weight (g / m) of the entire lower core 32 is not limited to the above. ２ ) is the average basis weight (g / m ２ The comparison of the average basis weight can be performed by a known method. For example, the upper core 31 and the lower core 32 are separated from the diaper 1, and the weight (g) and the outer area (m ２ ) and calculate the basis weight.

[0166] Furthermore, like the absorbent cores 30 described in the previous embodiments, the absorbent core 30 of the fifth embodiment also has a configuration in which an upper core 31 and a lower core 32 are stacked, and at least a portion of a groove region A3 is provided in the overlapping portion of the upper core 31 and the lower core 32. In other words, the upper core 31 and the lower core 32 are stacked, and the groove region A3 is provided in an area of ​​the absorbent core 30 that has a relatively high basis weight and high excrement retention capacity. Therefore, even if the portion of the absorbent core 30 where the groove region A3 is located absorbs a large amount of excrement, rewetting from the groove region A3 can be suppressed compared to a single-layer absorbent core.

[0167] 17 illustrates an absorbent core 30 in which the upper core 31 is shorter in the width direction and longitudinal direction than the lower core 32. However, without being limited thereto, for example, the lower core 32 may be shorter in the width direction and longitudinal direction than the upper core 31, or the width direction length of the upper core 31 may be longer (or shorter) than the width direction length of the lower core 32, but the longitudinal direction length of the upper core 31 may be shorter (or longer) than the longitudinal direction length of the lower core 32. Also, in FIG. 17, the lower core 32 extends more on both sides in the longitudinal direction than the upper layer core 31. However, without being limited thereto, for example, the upper layer core 31 may extend more on both sides in the longitudinal direction than the lower layer core 32, or the lower layer core 32 may extend more longitudinally than the upper layer core 31 on one longitudinal side, and the upper layer core 31 may extend more longitudinally than the lower layer core 32 on the other longitudinal side.

[0168] Furthermore, most of the excretory liquid not absorbed by the absorbent core 30 at the excretory-port contact portion flows through the widthwise center of the absorbent core 30 toward the longitudinal rear. Therefore, it is preferable to provide a groove 36 in the lower core 32 in the widthwise center of the rear first region 30B1. However, this region is prone to body pressure and rewet. Therefore, as shown in FIG. 17 , the lower core 32 located in the widthwise center of the rear first region 30B1 preferably has a region in which only one main groove 361 is located, the length of which is greater in the longitudinal direction than in the widthwise direction. In other words, it is preferable to have a region in which multiple main grooves 361 are not aligned in the widthwise direction. By doing so, excretory liquid flowing from the excretory-port contact portion to the rear first region 30B1 passes through the upper core 31, and is then absorbed into the lower core 32 by the groove region A3 of the lower core 32 while being dispersed in the longitudinal direction. Therefore, the excreted liquid flowing from the excretion port contact portion can be smoothly transferred from the upper core 31 to the inside of the lower core 32, thereby suppressing leakage of the excreted liquid. Furthermore, the area ratio of the groove region A3 can be kept small, thereby reducing the amount of rewetting from the groove region A3.

[0169] 17, a plurality of main grooves 361 may be aligned in the width direction in a front portion (a portion close to the excretion opening contact portion) of the widthwise center portion of the rear first region 30B1. Further, the lower core 32 located in the widthwise center portion of the rear first region 30B1 may be provided with grooves 36 extending in a direction different from the longitudinal direction, or may not be provided with grooves 36 at all.

[0170] Comparison of the area ratios of the groove regions A3 of the lower core 32 and confirmation of the number of groove regions A3 can be performed by well-known methods. For example, if the absorbent core 30 (lower core 32) is separated or exposed from the diaper 1 and the groove regions A3 can be visually confirmed, the absorbent core 30 can be partitioned as shown in Figure 17, and then the area ratios of the groove regions A3 in target areas can be compared and the number confirmed visually. Alternatively, the groove regions A3 (outlines) can be identified on image data obtained by photographing the lower core 32 from the thickness direction, and the areas of the groove regions A3 can be actually calculated using area calculation software or the like and compared.

[0171] Furthermore, as mentioned above, the amount of X-ray transmission is reduced in areas where the superabsorbent polymer 34 overlaps more. Therefore, if the density (basis weight) of the superabsorbent polymer 34 in the groove regions A3 is lower than that in the non-groove regions A4, the groove regions A3 can be identified based on an image obtained by irradiating the lower core 32 with X-rays in the thickness direction. In other words, a density difference occurs between the groove regions A3 and the non-groove regions A4 in the X-ray image. Therefore, it is advisable to visually identify the groove regions A3 based on the density of the X-ray image, compare the area ratio of the groove regions A3 in the target area, or confirm the number of groove regions A3. Alternatively, the X-ray image may be binarized to identify the groove regions A3 (outlines), and the areas of the groove regions A3 may be calculated using area calculation software or the like for comparison.

[0172] Furthermore, most of the excretory liquid that is not absorbed by the absorbent core 30 at the excretion opening contact portion flows through the widthwise center portion of the absorbent core 30 to the longitudinal rear side. Therefore, the average basis weight (g / m) of the absorbent core 30 (upper core 31 and lower core 32) is higher in the widthwise center portion of the rear first region 30B1 than in the pair of widthwise side portions of the rear first region 30B1. ２17, in the rear first region 30B1, the upper core 31 and the lower core 32 are not present in a portion of the widthwise side portions (rectangular regions), whereas the upper core 31 and the lower core 32 are present throughout the entire widthwise central region (entire rectangular region).

[0173] This allows the absorbent core 30 in the widthwise center portion of the rear first region 30B1 to absorb and retain a large amount of excrement flowing from the excretory opening contact portion. Furthermore, although the widthwise center portion of the rear first region 30B1 is a region that is prone to receiving body pressure from the wearer, rewetting can be suppressed.

[0174] Furthermore, excreted liquid that is not completely absorbed by the absorbent core 30 located in the widthwise center of the rear first region 30B1 also tends to flow to the widthwise sides. Therefore, it is advisable to provide main grooves 361 in the lower cores 32 located in each of the pair of widthwise sides of the rear first region 30B1. By doing so, excreted liquid that flows to the widthwise sides and passes through the upper core 31 is absorbed into the lower core 32 by the main grooves 361 and diffused in the longitudinal direction. In other words, excreted liquid smoothly moves from the upper core 31 to the lower core 32 at the widthwise sides of the absorbent core 30, thereby suppressing leakage of excreted liquid, particularly side leakage.

[0175] The average basis weight of the absorbent core 30 can be compared by a known method. For example, the absorbent core 30 is separated from the diaper 1 and divided into sections as shown in FIG. 17 . Then, sections of the absorbent core 30 (a laminate of the upper core 31 and the lower core 32) located at the widthwise center and widthwise side of the rear first region 30B1 are cut out, and the weights (g) of each section are measured. In addition, the area a (m ２ Then, the weight (g) of the absorbent core 30 located at the widthwise center and widthwise side of the rear first region 30B1 is calculated based on the area a (m ２ ) to obtain the basis weight (g / m ２ ) is calculated.

[0176] The upper core 31 shown in Figure 17 has an hourglass-shaped planar shape. The upper core 31 is narrowest in the front second region 30F2, and is wider in the longitudinal front and rear regions than the front second region 30F2. The narrow portion of the upper core 31 (the front second region 30F2) is the excretory opening contact portion or a portion close to it. Therefore, it is preferable to provide a groove region A3 of the lower core 32 on the widthwise side of the wider portion of the upper core 31, which is longitudinally rearward of the narrow portion.

[0177] By doing so, similarly to the above, excreted liquid that flows rearward from the excretion port contact portion through the widthwise central portion of the absorbent core 30 and that cannot be completely absorbed in the widthwise central portion of the absorbent core 30 flows to the widthwise side portions of the absorbent core 30. After passing through the upper core 31, the excreted liquid is diffused by the groove regions A3 and absorbed into the lower core 32. In other words, at the widthwise side portions of the absorbent core 30, the excreted liquid smoothly moves from the upper core 31 to the inside of the lower core 32, thereby suppressing leakage of excreted liquid, particularly side leakage.

[0178] Furthermore, as shown in FIG. 18B, it is preferable that the lower core 32 has a region in which a non-groove region A4 is continuous from one end to the other end in the width direction between the groove region A3 of the lower core 32 located in the rear second region 30B2 and the groove region A3 of the lower core 32 located in the front second region 30F2.

[0179] As a result, in the front second region 30F2, which is the excretory opening contact portion or a region therearound, excreted liquid that has passed through the upper core 31 is smoothly absorbed into the lower core 32 by the groove region A3. The excreted liquid is firmly absorbed and retained in the non-groove region A2 rearward of the front second region 30F2, i.e., in a region of the lower core 32 with a higher basis weight, thereby preventing rewetting. Furthermore, excreted liquid that cannot be fully absorbed by the absorbent core 30 located in the front second region 30F2 and flows rearward passes through the upper core 31 in the rear second region 30B2, and is then diffused and absorbed into the lower core 32 by the groove region A3, preventing leakage of excreted liquid.

[0180] Furthermore, the value obtained by dividing the area of ​​the groove region A3 of the lower core 32 located in the widthwise center of the rear second region 30B2 by the area of ​​the widthwise center of the rear second region 30B2 is preferably greater than the value obtained by dividing the area of ​​the groove region A3 of the lower core 32 located in the widthwise center of the rear first region 30B1 by the area of ​​the widthwise center of the rear first region 30B1. Specifically, the widthwise center of the rear first region 30B1 has only one main groove 361 of the lower core 32 that is longer in the longitudinal direction than in the widthwise direction, while the widthwise center of the rear second region 30B2 has three main grooves 361.

[0181] In the rear second region 30B2 near the excretory opening contact portion, by increasing the area ratio of the groove region A3, a large amount of excretory liquid that flows from the excretory opening contact portion and passes through the upper core 31 can smoothly move into the lower core 32, thereby suppressing leakage of excretory liquid. On the other hand, in the rear first region 30B1 where the wearer's body pressure is likely to be applied, by decreasing the area ratio of the groove region A3, rewetting can be suppressed.

[0182] However, the present invention is not limited to the above, and the same number of main grooves 361 (here, one) as those in the widthwise center of the rear second region 30B1 may be provided in the widthwise center of the rear first region 30B1, as in the modified example shown in Fig. 19. For example, when a wearer with a large amount of excretion is intended, it is preferable to provide many groove regions A3 in the lower core 32 located in the widthwise center of the rear second region 30B2, as shown in Fig. 17. On the other hand, when a wearer with a small amount of excretion is intended, leakage of excreted fluid can be suppressed by providing a smaller number of groove regions A3 in the lower core 32 located in the widthwise center of the rear second region 30B2, as shown in Fig. 19.

[0183] Furthermore, the lower core 32 located in the widthwise center of the front first region 30F1 preferably has more main grooves 361 that are longer in the longitudinal direction than in the widthwise direction, compared to the lower core 32 located in the widthwise center of the front second region 30F2. In the lower core 32 shown in Figure 17, the front second region 30F2 has two main grooves 361, while the front first region 30F1 has four main grooves 361. Preferably, the area ratio of the groove region A3 of the lower core 32 in the front first region 30F1 is larger than that of the front second region 30F2.

[0184] As described above, the front first region 30F1 is less susceptible to the wearer's body pressure than the front second region 30F2, which contacts the wearer's crotch area. Therefore, even if the number of main grooves 361 is increased, rewetting of excreted fluid can be suppressed. Furthermore, in the case of a male wearer, a relatively front portion becomes the excretory opening contact portion. Therefore, by increasing the number of main grooves 361 in the front first region 30F1, a large amount of excreted fluid excreted from the excretory opening passes through the upper core 31, and then is quickly absorbed and diffused into the lower core 32 by the multiple main grooves 361. Therefore, leakage of excreted fluid can be suppressed.

[0185] Furthermore, in the widthwise center of the first rear region 30B1 and the widthwise center of the second rear region 30B2, the main groove 361 of the lower core 32 is provided on the center line that divides the rectangular region in half in the width direction. This makes it easier for excreted liquid that flows from the excretion opening contact portion through the widthwise center of the absorbent core 30 to the rear side and passes through the upper core 31 to flow into the groove region A3 of the lower core 32 and be easily absorbed inside the lower core 32.

[0186] In contrast, in the widthwise center of the front first region 30F1 and the widthwise center of the front second region 30F2, the main groove 361 of the lower core 32 is not provided on the center line that divides the rectangular region in half widthwise, but is provided on both sides. This makes it less likely that the wearer's excretory opening will be positioned on the main groove 361 of the lower core 32, ensuring the basis weight of the absorbent core 30 in the area that receives the most excreted fluid. This effectively suppresses rewetting.

[0187] As shown in Fig. 15, the diaper 1 also has a pair of leakage preventing walls 19 that can stand up on the skin side on both widthwise sides of the absorbent core 30 (absorbent body 10). Specifically, as shown in Fig. 16, the side sheets 14 are folded back from the widthwise side edges of the back sheet 13 on the non-skin side toward the widthwise side edges of the top sheet 11 on the skin side. Leak preventing wall elastic members 15 are fixed to the widthwise inner ends of the folded side sheets 14 in a state stretched in the longitudinal direction.

[0188] 15 , the side sheet 14 is joined to the skin side of the topsheet 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 from one end of the absorbent main body 10 to the other in the longitudinal direction. The second joining portion 192 is provided at both longitudinal ends of the absorbent main body 10, widthwise inward of the first joining portion 191. Therefore, a portion of the side sheet 14 that is widthwise inward of the widthwise inner end (standing fulcrum) of the first joining portion 191 and lengthwise inward of the lengthwise inner end (standing fulcrum) of the second joining portion 192 can stand up toward the skin, and this portion serves as the leakage preventing wall portion 19.

[0189] When the diaper 1 has the leakage preventing walls 19, it is preferable that the lower core 32 has a groove region A3 that at least partially overlaps with the leakage preventing walls 19 when the diaper 1 is in an unfolded and stretched state (FIG. 15) and viewed in the thickness direction. This allows excreted liquid that has been blocked by the leakage preventing walls 19 and absorbed into the upper core 31 to be quickly absorbed into the lower core 32 from the groove region A3. This prevents excreted liquid from leaking beyond the leakage preventing walls 19.

[0190] Furthermore, in the regions where the leakage preventing walls 19 are provided, the wearer's skin does not come into direct contact with the topsheet 11 but comes into contact with it via the sidesheet 14. Therefore, even if excrement rewets from the groove regions A3 that overlap the leakage preventing walls 19 in the thickness direction, the wearer is unlikely to feel the rewet, preventing a decrease in the comfort of the diaper 1. Furthermore, the leakage preventing walls 19 that stand up against the skin due to contraction of the leakage preventing wall elastic members 15 are likely to function as a cushioning material, and the wearer's body pressure is unlikely to be applied to the regions where the leakage preventing walls 19 are provided. Therefore, rewet can be suppressed even when the groove regions A3 are provided in the regions that overlap the leakage preventing walls 19 in the thickness direction.

[0191] Also, as shown in Figure 16, when the upper core 31 also contains superabsorbent polymer 34, like the lower core 32, 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.

[0192] Compared to excreted liquid present between the liquid-absorbent fibers, excreted liquid held in the superabsorbent polymer 34 is less likely to move freely and is less likely to rewet. Therefore, by increasing the average density of the superabsorbent polymer 34 in the upper core 31, excreted liquid that has rewet from the lower core 32 (particularly the groove region A3) onto the upper core 31 can be firmly held by the superabsorbent polymer 34 of the upper core 31. Therefore, even if the wearer's body pressure is applied to the absorbent core 30, rewetting from the upper core 31 onto the topsheet 11 can be suppressed.

[0193] Furthermore, although the upper core 31 of the fifth embodiment does not have the groove region A1 (groove 35), the present invention is not limited to this. The upper core 31 may have a groove 35 (upper groove) recessed from the skin-side surface to the non-skin-side surface in the thickness direction, or the upper core 31 may have a groove 35 (lower groove) recessed from the non-skin-side surface to the skin-side surface in the thickness direction.

[0194] When the upper core 31 has the groove region A1, the area ratio of the groove region A1 of the upper core 31 located at the widthwise center of the rear first region 30B1 should be relatively small, similar to the lower core 32. For example, the area ratio of the groove region A1 of the upper core 31 located at the widthwise center of the front first region 30F1 should be smaller than that of the groove region A1 of the upper core 31 located at the widthwise center of the front first region 30F1.

[0195] By providing the groove region A1 in the upper core 31 located at the widthwise center of the rear first region 30B1, excreted liquid that flows from the excretion opening contact portion through the widthwise center of the absorbent core 30 to the rear first region 30B1 can be drawn into the absorbent core 30 by the groove region A1 of the upper core 31, thereby suppressing leakage of excreted liquid. However, by reducing the area ratio, rewetting can be suppressed.

[0196] On the other hand, the front first region 30F1 is the excretory opening contact portion or a portion close to it. Therefore, by increasing the area ratio of the groove region A1 of the upper core 31 located in the widthwise center of the front first region 30F1, a large amount of excreted liquid from the wearer can be quickly absorbed into the absorbent core 30 by the groove region A1 of the upper core 31, thereby suppressing leakage of the excreted liquid.

[0197] When viewed in the thickness direction of the absorbent core 30, the groove region A1 of the upper core 31 and the groove region A3 of the lower core 32 may be aligned or offset. If they are aligned, excrement absorbed from the groove region A1 of the upper core 31 can be quickly absorbed and diffused into the lower core 32 by the groove region A3 of the lower core 32. In contrast, if the groove regions A1 and A3 are offset from each other, a local decrease in basis weight of the absorbent core 30 in which the groove regions A1 and A3 are arranged can be prevented, and rewetting from the groove regions A1 and A3 can be prevented.

[0198] Although the embodiments of the present invention have been described above, the above embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Furthermore, the present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

[0199] For example, the upper core 31 is not limited to an absorbent core formed into a predetermined shape from liquid-absorbent fibers 33 containing superabsorbent polymers 34. The upper core 31 may be an SAP sheet formed by adhering an SAP layer to a hydrophilic sheet, an airlaid sheet formed by forming liquid-absorbent fibers into a sheet shape by an airlaid method, or the like.

[0200] DESCRIPTION OF SYMBOLS 1 (Pants-type) diaper (absorbent article), 2 Joint portion, 10 Absorbent body, 11 Top sheet, 12 Intermediate sheet, 13 Back sheet, 14 Side sheet, 15 Leak-barrier wall elastic member, 16 Leg-hole elastic member, 17 Crotch elastic member (elastic member), 18 Cover sheet, 20 Outer member, 21 Front waistband portion, 22 Rear waistband portion, 23 Crotch portion, 211, 221 Waistband elastic member, 212, 222 Leg-hole elastic member, 30 Absorbent core, 31 Upper core, 32 Lower core, 33 Liquid-absorbent fiber, 34 Superabsorbent polymer, 35 Groove (second groove), 36 Groove, 37 Central slit (slit), 38 Side slit, 39 Core wrap sheet, A1 Groove region (second groove region), A2 Non-groove region (second non-groove region), A3 groove region, A4 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 comprises an upper core and a lower core arranged on the non-skin side of the upper core in the thickness direction, the lower core comprising a superabsorbent polymer and a groove formed by a recess in a portion of the lower core in the thickness direction, the groove having a length in a predetermined direction, the lower core having, as viewed in the thickness direction, a groove region in which the groove is provided and a non-groove region in which the groove is not provided, at least a portion of the groove region being provided in a region where the upper core and the lower core overlap as viewed in the thickness direction, and wherein when the lower core is divided in half 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, the average density of the superabsorbent polymer in the 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.

2. An absorbent article as described in claim 1, wherein the absorbent core has a widthwise central portion and a pair of widthwise side portions that are defined by dividing its maximum width into thirds in the width direction, and has a front portion located in front of a center line that divides the absorbent article in half in the longitudinal direction when it is in an unfolded and stretched state, and a rear portion located behind the center line in the longitudinal direction, the rear portion having a rear first region that is the central region when its maximum length is divided into thirds in the longitudinal direction, and the front portion having a front first region that is the central region when its maximum length is divided into thirds in the longitudinal direction, and the value obtained by dividing the area of ​​the groove region of the lower core located in the widthwise central portion of the rear first region by the area of ​​the widthwise central portion of the rear first region is smaller than the value obtained by dividing the area of ​​the groove region of the lower core located in the widthwise central portion of the front first region by the area of ​​the widthwise central portion of the front first region.

3. An absorbent article as described in claim 2, characterized in that the lower core located in the widthwise center of the rear first region has an area in which only one groove having a length in the longitudinal direction, which is the specified direction, is located.

4. An absorbent article as described in claim 2 or 3, characterized in that the average basis weight of the absorbent core is higher in the widthwise central portion of the rear first region than in the pair of widthwise side portions of the rear first region, and the lower cores located on each of the pair of widthwise side portions of the rear first region have grooves having a length in the longitudinal direction, which is the specified direction.

5. An absorbent article as claimed in any one of claims 2 to 4, wherein the rear portion has a rear second region located forward in the longitudinal direction from the rear first region, and the front portion has a front second region located rearward in the longitudinal direction from the front first region, and the lower core has a region in which the non-groove region is continuous from one end to the other end in the width direction between the groove region of the lower core located in the rear second region and the groove region of the lower core located in the front second region in the longitudinal direction.

6. An absorbent article as claimed in any one of claims 2 to 5, wherein the rear portion has a rear second region located forward in the longitudinal direction of the rear first region, and the value obtained by dividing the area of ​​the groove region of the lower core located in the widthwise center of the rear second region by the area of ​​the widthwise center of the rear second region is greater than the value obtained by dividing the area of ​​the groove region of the lower core located in the widthwise center of the rear first region by the area of ​​the widthwise center of the rear first region.

7. An absorbent article as claimed in any one of claims 2 to 6, characterized in that the front portion has a front second region located rearward in the longitudinal direction from the front first region, and the lower core located in the widthwise center of the front first region has a greater number of grooves having a length in the longitudinal direction, which is the specified direction, than the lower core located in the widthwise center of the front second region.

8. An absorbent article according to any one of claims 2 to 7, characterized in that the average basis weight of the lower core is higher than the average basis weight of the upper core.

9. An absorbent article as claimed in any one of claims 1 to 8, characterized in that the absorbent article has a pair of leak-proof wall portions that can stand up on the skin side on both sides of the absorbent core in the width direction, and when the absorbent article in an unfolded and stretched state is viewed in the thickness direction, the lower core has a groove region that at least partially overlaps with the leak-proof wall portions.

10. An absorbent article according to any one of claims 1 to 9, wherein the upper core contains a superabsorbent polymer, and 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.

11. An absorbent article according to any one of claims 1 to 10, characterized in that 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.

12. An absorbent article according to any one of claims 1 to 11, characterized in that the groove is a groove recessed from the non-skin side of the lower core to the skin side in the thickness direction.

13. An absorbent article as claimed in any one of claims 1 to 12, wherein the upper core comprises a superabsorbent polymer, and when the upper core is divided in half 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, and wherein, 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 opposite the certain region.

14. An absorbent article as claimed in any one of claims 1 to 13, characterized in that the grooves have a main groove having a length in the longitudinal direction, which is the predetermined direction, and a minor groove extending from the main groove in the width direction, the plurality of main grooves being arranged at intervals in the width direction, and the plurality of minor grooves extending from the main groove in the width direction at intervals in the longitudinal direction.

15. An absorbent article as claimed in any one of claims 1 to 14, wherein the upper core comprises a superabsorbent polymer and has a second groove formed by recessing a portion of the upper core in the thickness direction, the second groove having a length in the longitudinal direction, the upper core having, as viewed in the thickness direction, a second groove region in which the second groove is provided and a second non-groove region in which the second groove is not provided, at least a portion of the second groove region being provided in a region in which the upper core and the lower core overlap as viewed in the thickness direction, and wherein when the upper core is divided in half 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, 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.

16. An absorbent article according to claim 15, 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.

17. An absorbent article according to claim 15 or 16, characterized in that the second groove is a groove recessed from the skin side of the upper core to the non-skin side in the thickness direction.

18. An absorbent article according to any one of claims 15 to 17, characterized in that, when viewed in the thickness direction, the groove region of the lower core has a portion that overlaps with the second groove region of the upper core.

19. An absorbent article as described in any one of claims 15 to 18, wherein the lower core has a slit penetrating the lower core in the thickness direction at the center of the width direction of the area where the wearer's crotch contacts, the slit having a length in the longitudinal direction, and when viewed in the thickness direction, the slit of the lower core overlaps with the upper core, and at least a portion of the slit of the lower core does not overlap with the second groove area of ​​the upper core.

20. An absorbent article as described in claim 19, characterized in that an elastic member that stretches in the longitudinal direction is arranged in the area that comes into contact with the wearer's crotch, when viewed in the thickness direction, the entire area of ​​the slit in the lower core does not overlap with the second groove area of ​​the upper core, and when viewed in the thickness direction, the slit has a portion that overlaps with the elastic member.

21. An absorbent article as claimed in any one of claims 1 to 20, wherein the lower core has a pair of side slits penetrating the lower core in the thickness direction on the widthwise sides of the region where the wearer's crotch contacts, and the groove region is provided outside the pair of side slits in the widthwise direction and at a position overlapping at least a portion of the pair of side slits in the longitudinal direction.

22. An absorbent article as claimed in any one of claims 1 to 21, wherein the lower core has a slit penetrating the lower core in the thickness direction in the widthwise central part of the region where the wearer's crotch contacts, the slit having a length in the longitudinal direction, the groove region having a length in the longitudinal direction which is the predetermined direction, the lower core having a region in the longitudinal direction rearward of the slit in which the non-groove region is continuous from one end to the other end in the width direction, and the rear end of the longitudinal direction of the upper core is located in the region in which the non-groove region is continuous.

23. An absorbent article as claimed in any one of claims 1 to 22, characterized in that the lower layer core extends longitudinally outward beyond the longitudinal ends of the upper layer core, and the groove region is provided in the portion of the lower layer core that extends longitudinally outward beyond the upper layer core.

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