absorbent materials

Abstract

In an absorbent article (1) having an upper core (31) and a lower core (32), the lower core (32) has a groove (36) that is recessed in the thickness direction and has a length along a predetermined direction. The lower core (32) has a grooved region in which the groove (36) is provided and a non-grooved region in which the groove (36) is not provided. At least a portion of the grooved region is located in the region where the upper core (31) and the lower core (32) overlap when viewed from the thickness direction. The average density of the superabsorbent polymer (34) on the skin side of the grooved region is lower than the average density of the superabsorbent polymer (34) on the skin side of the non-grooved region.

Description

Technical Field

[0001] This invention relates to an absorbent article. Background Technology

[0002] Patent Document 1 discloses an absorbent article comprising an absorbent body with a two-layer structure, including an upper absorbent body and a lower absorbent body. A slit penetrating at least in the thickness direction is provided at the center of the upper absorbent body in the width direction. Furthermore, the weight ratio of superabsorbent polymer to pulp fiber in the upper absorbent body is higher than that in the lower absorbent body. According to this configuration, excreted liquid is also supplied to the upper absorbent body to a certain extent, but preferentially supplied to the lower absorbent body through the slit. After the lower absorbent body reaches saturation, the liquid absorbed by the lower absorbent body is drawn upwards by the upper absorbent body and retained by the superabsorbent polymer of the upper absorbent body. For this reason, this structure is considered to have excellent anti-rewetting (backflow) function.

[0003] Citation List

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-63923 Summary of the Invention

[0006] Technical issues

[0007] In an absorber with a two-layer structure, absorption capacity can be improved. However, excreted liquid is more likely to accumulate in the thickness direction in the space between the upper absorber (upper core) and the lower absorber (lower core). In this case, the amount of excreted liquid absorbed by the lower absorber is reduced, thus failing to effectively utilize the absorption performance of the lower absorber.

[0008] Furthermore, if a relatively large slit is provided in the upper absorber (upper core) as in Patent Document 1, the excreted liquid is more likely to accumulate. In Patent Document 1, the weight ratio of the superabsorbent polymer in the lower absorber is reduced, thereby allowing the excreted liquid to be absorbed and dispersed over a larger area. However, the absorption and dispersion of the excreted liquid supplied locally through the slit by the lower absorber is limited. The dispersion capacity of the discharged liquid in the lower absorber is insufficient.

[0009] The present invention was made in view of the above-mentioned problems. One aspect of the present invention is to provide an absorbent article comprising an upper core and a lower core that overlap each other, the absorbent article being able to suppress the accumulation of excreted liquid at the boundary between the upper core and the lower core, and effectively utilizing the absorption performance of the lower absorbent by improving the dispersion ability of the excreted liquid in the lower absorbent.

[0010] Solution to the problem

[0011] A key aspect of the present invention for achieving the above-mentioned aspects is an absorbent article having a longitudinal direction, a width direction, and a thickness direction. The absorbent article includes an absorbent core comprising an upper core and a lower core, the lower core being disposed on a non-skin side relative to the upper core in the thickness direction. The lower core comprises a superabsorbent polymer and has a groove in which a portion of the lower core is recessed in the thickness direction. The groove is elongated in a predetermined direction. When viewed in the thickness direction, the lower core has a grooved region in which the groove is provided and a non-grooved region in which the groove is not provided. When viewed in the thickness direction, at least a portion of the grooved region is disposed in the region where the upper core and the lower core overlap. When the lower core is divided into two parts in the thickness direction, the average density of the superabsorbent polymer in the skin-side portion of the grooved region is lower than the average density of the superabsorbent polymer in the skin-side portion of the non-grooved region, wherein the skin-side portion is the portion located on the skin side, and the non-skin-side portion is the portion located on the non-skin side.

[0012] Other features of the invention, in addition to those described above, will become clear from reading the description in this specification and referring to the accompanying drawings.

[0013] Advantages of the present invention

[0014] According to the present invention, an absorbent article comprising an upper core and a lower core that overlap each other can be provided, which inhibits the accumulation of excreted liquid at the boundary between the upper core and the lower core, and effectively utilizes the absorption performance of the lower absorbent by improving the dispersion ability of the excreted liquid in the lower absorbent. Attached Figure Description

[0015] Figure 1 : This is a schematic three-dimensional diagram of an underwear-style diaper 1 (hereinafter also referred to as "diaper").

[0016] Figure 2 : A schematic plan view of diaper 1 in an unfolded and stretched state when viewed from the skin side.

[0017] Figure 3 : is along Figure 2 A schematic cross-sectional view taken from line aa.

[0018] Figure 4 : is a planar view of the upper core 31 when viewed from the skin side in the thickness direction.

[0019] Figure 5 : This is a planar view of the lower core 32 as seen from the skin side in the thickness direction.

[0020] Figure 6 : is a plan view of the upper core 31 and lower core 32 in an overlapping state when viewed from the skin side in the thickness direction.

[0021] Figure 7 : A schematic cross-sectional view of a portion of the upper core 31 and the lower core 32.

[0022] Figure 8: Figure 8A It is along Figure 6 A schematic cross-sectional view taken from line II in the middle. Figure 8B It is along Figure 6 A schematic cross-sectional view taken from line II-II.

[0023] Figure 9: Figure 9A This is a schematic 3D diagram of chip 39. Figure 9B This is an illustrative view of a variant of the arrangement of chip 39.

[0024] Figure 10: Figure 10A and 10B These are illustrative views of variations of grooves 35 and 36.

[0025] Figure 11: Figure 11A and 11B These are illustrative views of variations of grooves 35 and 36.

[0026] Figure 12 : is a schematic cross-sectional view of the absorber core 30 according to the second embodiment.

[0027] Figure 13 : is a schematic cross-sectional view of the absorber core 30 according to the third embodiment.

[0028] Figure 14: Figure 14A and 14B This is a schematic cross-sectional view of the absorber core 30 according to the fourth embodiment.

[0029] Figure 15 : is a schematic plan view of the diaper 1 according to the fifth embodiment when viewed from the skin side in the unfolded and stretched state.

[0030] Figure 16 : is along Figure 15 A schematic cross-sectional view taken from section AA in the image.

[0031] Figure 17 : is a plan view of the upper core 31 and lower core 32 in an overlapping state when viewed from the non-skin side in the thickness direction.

[0032] Figure 18: Figure 18A This is a plan view of the upper core 31 when viewed from the skin side in the thickness direction. Figure 18BThis is a plan view of the lower core 32 when viewed from the non-skin side in the thickness direction.

[0033] Figure 19 : is a plan view of the absorbent core 30 in the fifth embodiment when viewed from the non-skin side in the thickness direction. Detailed Implementation

[0034] At least the following will become clear from the description in this specification and the accompanying drawings.

[0035] An absorbent article having a longitudinal direction, a width direction, and a thickness direction, the absorbent article comprising: an absorbent core, the absorbent core including an upper core and a lower core, the lower core being disposed on a non-skin side relative to the upper core in the thickness direction, the lower core including a superabsorbent polymer, the lower core having a groove in which a portion of the lower core is recessed in the thickness direction, the groove being elongated in a predetermined direction, and, when viewed in the thickness direction, the lower core having a grooved region in which the groove is provided and a non-grooved region in which the groove is not provided, at least a portion of the grooved region being disposed in the region where the upper core and the lower core overlap, and, when the lower core is divided into two parts in the thickness direction, the average density of the superabsorbent polymer in the skin-side portion of the grooved region is lower than the average density of the superabsorbent polymer in the skin-side portion of the non-grooved region, wherein the skin-side portion is the portion located on the skin side and the non-skin-side portion is the portion located on the non-skin side.

[0036] According to this absorbent article, excreted liquid from the upper core can be drawn into the grooves (where the average density of the superabsorbent polymer is low) of the skin-side portion of the lower core, or it can fall into the space within the grooves. Therefore, the excreted liquid can be dispersed along the groove region in a predetermined direction. This suppresses the accumulation of excreted liquid at the boundary between the upper and lower cores, thereby improving the dispersion ability of the excreted liquid in the lower core. Thus, the absorbency of the lower core can be effectively utilized. Furthermore, since the excreted liquid absorbed in the skin-side portion of the non-grooved region of the lower core is retained by the superabsorbent polymer, rewetting of the excreted liquid into the upper core can be suppressed.

[0037] In such an absorbent article, the absorbent core has a central portion in the width direction and a pair of side portions in the width direction, the central portion and the pair of side portions in the width direction being defined by dividing the maximum width of the absorbent core into three parts in the width direction. The absorbent core has a front portion located in the longitudinal direction relative to the product centerline and a rear portion located in the longitudinal direction relative to the product centerline, the product centerline being a line that divides the absorbent article in its unfolded and stretched state into two parts in the longitudinal direction. The rear portion has a rear first region, the rear first region being... The central region is obtained by dividing the maximum length of the rear portion into three parts in the longitudinal direction. The front portion has a front first region, which is a central region obtained by dividing the maximum length of the front portion into three parts in the longitudinal direction. The value obtained by dividing the area of ​​the groove region of the lower core of the central portion in the width direction of the rear first region into the area of ​​the central portion in the width direction of the rear first region is less than the value obtained by dividing the area of ​​the groove region of the lower core of the central portion in the width direction of the front first region into the area of ​​the central portion in the width direction of the front first region.

[0038] According to this absorbent article, in the central portion of the rear first region in the width direction (where the wearer's body weight is easily applied), the area ratio of the recessed area of ​​the lower core is small, thus reducing the amount of excrement fluid from the recessed area that causes rewetting. On the other hand, in the front first region (which is the portion in contact with or close to the source of excretion), the area ratio of the recessed area of ​​the lower core is large, allowing excrement fluid from the upper core to be dispersed while being rapidly absorbed into the lower core by the recessed area. This prevents excrement fluid from accumulating at the boundary between the upper and lower cores, and from leaking out beyond the skin-side surface of the absorbent article due to incomplete absorption by the upper core.

[0039] In such an absorbent article, a portion of the lower core in the central part of the rear first region in the width direction has a region provided with only one groove, the groove being elongated in the longitudinal direction, the longitudinal direction being the predetermined direction.

[0040] According to this absorbent article, the central portion of the rear first region in the width direction (i.e., the area where the wearer's body weight is easily applied) includes an area where multiple recessed areas arranged side-by-side in the width direction are not arranged, thus suppressing rewetting. Furthermore, excreted liquid flowing from the portion in contact with the source of excretion to the rear first region passes through the upper core and is then rapidly absorbed into the lower core by the recessed areas of the lower core while being dispersed. This makes it possible to suppress leakage of excreted liquid.

[0041] In such an absorbent article, the average weight per unit area of ​​the absorbent core is higher in the central portion in the width direction of the rear first region than in a pair of side portions in the width direction of the rear first region, and each of the lower core portions in the pair of side portions in the width direction of the rear first region has an elongated groove in the longitudinal direction, which is the predetermined direction.

[0042] According to this absorbent article, the absorption and retention capacity of excretory liquid is improved in the central portion of the rear first region in the width direction (where the wearer's body weight is easily applied), thus suppressing rewetting. Furthermore, excretory liquid flowing from the portion in contact with the source of excretion to the rear first region can be rapidly absorbed into the lower core by the grooved area of ​​the lower core located in the width direction while being dispersed in the longitudinal direction. This makes it possible to suppress leakage of excretory liquid (lateral leakage).

[0043] In such an absorbent article, the rear portion has a rear second region located on the front side relative to the rear first region in the longitudinal direction, the front portion has a front second region located on the rear side relative to the front first region in the longitudinal direction, and the lower core has a region in which, in the longitudinal direction, between the groove region of the lower core located on the rear second region and the groove region of the lower core located on the front second region, a non-grooved region is continuous from one end to the other in the width direction.

[0044] According to this absorbent article, a large amount of excreted liquid can be rapidly absorbed from the upper core into the lower core by the grooved region of the lower core located in the front second region (which is the part in contact with or close to the excretion source). The absorbed excreted liquid can be retained in the non-grooved area, and rewetting can be suppressed. In addition, excreted liquid that is not completely absorbed by the front second region and flows backward can be absorbed into the lower core by the grooved region of the lower core located in the rear second region. This makes it possible to suppress leakage of excreted liquid.

[0045] In such an absorbent article, the rear portion has a rear second region located on the front side relative to the rear first region in the longitudinal direction, and the value obtained by dividing the area of ​​the groove region of the lower core in the width direction of the central portion of the rear second region by the area of ​​the central portion in the width direction of the rear second region is greater than the value obtained by dividing the area of ​​the groove region of the lower core in the width direction of the central portion of the rear first region by the area of ​​the central portion in the width direction of the rear first region.

[0046] According to this absorbent article, the area ratio of the recessed region of the lower core is smaller in the central portion of the first rear region in the width direction (where the wearer's body weight is easily applied), thus suppressing rewetting. On the other hand, the area ratio of the recessed region of the lower core is larger in the second rear region (the portion closer to the source of excretion), so that excreted liquid that has passed through the upper core can be rapidly absorbed into the lower core by the recessed region of the lower core and dispersed. This helps to suppress leakage of excreted liquid.

[0047] In such an absorbent article, the front portion has a front second region located behind the front first region in the longitudinal direction, and a portion of the lower core in the central portion in the width direction of the front first region has a greater number of longitudinally elongated grooves than a portion of the lower core in the central portion in the width direction of the front second region, wherein the longitudinal direction is the predetermined direction.

[0048] According to this absorbent material, the first front area is less likely to bear the wearer's body weight compared to the second front area that contacts the wearer's groin area. Therefore, even with a greater number of grooves, rewetting is less likely to occur. Furthermore, in the case of a male wearer, the first front area is the part in contact with or close to the source of excretion. Therefore, excretory fluid excreted from the source and passing through the upper core can be rapidly absorbed into the lower core by the numerous grooves in the lower core and dispersed. This helps to suppress leakage of excretory fluid.

[0049] In such absorbent materials, the average weight per unit area of ​​the lower core is higher than that of the upper core.

[0050] According to this absorbent material, the upper core has a relatively low absorption and retention capacity, allowing drained liquid to be rapidly absorbed into the lower core through the grooved areas of the upper core and dispersed. This makes it possible to more effectively suppress leakage of drained liquid.

[0051] In such an absorbent article, the absorbent article further includes a pair of leak-proof wall portions in two side portions in the width direction of the absorbent core, the pair of leak-proof wall portions being able to rise to the skin side, and when the absorbent article is viewed in the thickness direction in an unfolded and stretched state, the lower core has a grooved area that at least partially overlaps with the leak-proof wall portions.

[0052] According to this absorbent article, the excreted liquid blocked by the leak-proof wall portion and absorbed by the upper core can be dispersed while being rapidly drawn into the lower core in the grooved area of ​​the lower core. In addition, in the portion including the leak-proof wall portion, the leak-proof wall portion can act as a cushioning material and is not easily able to bear the weight of the body, thus inhibiting rewetting in the grooved area.

[0053] In this absorbent article, the upper core comprises 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.

[0054] According to this absorbent article, even if the excreted liquid absorbed by the lower core causes rewetting of the upper core (in particular, where rewetting of the excreted liquid from the grooved area of ​​the lower core to the upper core is likely to occur), the excreted liquid is retained by the superabsorbent polymer in the upper core. Therefore, rewetting of the skin-side surface of the absorbent article can be suppressed.

[0055] In such absorbent articles, the average density of superabsorbent polymers in the non-skin side portion of the non-grooved region is lower than the average density of superabsorbent polymers in the skin side portion of the non-grooved region.

[0056] According to this absorbent article, excreted liquid that has passed through the grooved region of the lower core and moved to the non-skin side portion is easily absorbed by the non-skin side portion of the non-grooved region (where the density of the superabsorbent polymer is lower). Therefore, the dispersion ability of the excreted liquid in the non-skin side portion of the lower core is improved. Furthermore, the excreted liquid that has moved to the non-skin side portion of the non-grooved region is adsorbed by the skin side portion of the non-grooved region and retained by the superabsorbent polymer, thereby suppressing rewetting of the excreted liquid into the upper core.

[0057] In such absorbent articles, the groove is a recessed groove in the thickness direction from the non-skin side surface of the underlying core towards the skin side.

[0058] According to this absorbent article, the ability of liquid to penetrate into the non-skin side portion (to the space within the groove) of the lower core is improved. Therefore, after the excreted liquid is reliably drawn to the non-skin side portion of the lower core, the excreted liquid can be dispersed along the groove, and the absorbency of the lower core can be effectively utilized.

[0059] In such absorbent materials,

[0060] The upper core comprises a superabsorbent polymer, and

[0061] When the upper core is divided into two parts in the thickness direction

[0062] In at least a portion of the lower core, the average density of the superabsorbent polymer in the skin-side portion of a given region of the lower core is higher than the average density of the superabsorbent polymer in the non-skin-side portion of the upper core facing the given region.

[0063] The skin-side portion is the portion located on the side of the skin.

[0064] The non-skin side portion is the portion located on the non-skin side.

[0065] According to this absorbent article, the movement speed of liquid from the upper core to the lower core can be appropriately suppressed. Therefore, the ability of the excreted liquid to disperse in the upper core is improved, and the excreted liquid is extensively absorbed in the lower core where it receives the excreted liquid.

[0066] In such absorbent materials,

[0067] The groove includes:

[0068] The main groove, which is elongated in the predetermined direction that is the longitudinal direction; and

[0069] A secondary groove extending from the main groove in the width direction.

[0070] Multiple main grooves are arranged side-by-side at intervals in the width direction, and

[0071] Multiple secondary grooves extend from each main groove in the width direction and are positioned to be spaced apart in the longitudinal direction.

[0072] According to this absorbent article, excreted liquid can be dispersed in the lower core in the longitudinal direction and along the secondary grooves in the width direction. Furthermore, the flexibility of the lower core is increased, and the lower core can easily deform along the wearer's body.

[0073] In such absorbent materials.

[0074] The upper core comprises a superabsorbent polymer, and

[0075] The upper core has a second groove in which a portion of the upper core is recessed in the thickness direction.

[0076] The second groove is elongated in the longitudinal direction.

[0077] When viewed in the thickness direction, the upper core has:

[0078] The second groove region, wherein the second groove is provided; and

[0079] The second non-groove region is where the second groove is not provided.

[0080] When viewed along the thickness direction, at least a portion of the second groove region is disposed in the area where the upper core and the lower core overlap, and

[0081] When the upper core is divided into two parts in the thickness direction

[0082] The average density of superabsorbent polymers in the skin-side portion of the second groove region is lower than the average density of superabsorbent polymers in the skin-side portion of the second non-groove region.

[0083] The skin-side portion is the portion located on the side of the skin.

[0084] The non-skin side portion is the portion located on the non-skin side.

[0085] According to this absorbent article, 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 average density of the superabsorbent polymer is lower, or it can fall into the space within the second groove region. This improves the ability to disperse the excreted liquid in the upper core. Furthermore, since the lower core receives and absorbs the excreted liquid dispersed in the upper core, the ability to disperse the excreted liquid in the lower core is also improved.

[0086] In addition, since the excretory fluid absorbed in the skin side portion of the second non-groove region is retained by the superabsorbent polymer, the rewetting of the excretory fluid to the skin side surface of the upper core can be suppressed.

[0087] In such absorbent articles, the average density of the superabsorbent polymer in the non-skin side portion of the second non-grooved region is lower than the average density of the superabsorbent polymer in the skin side portion of the second non-grooved region.

[0088] According to this absorbent article, excreted liquid that has passed through the second groove region of the upper core and moved to the non-skin side portion is easily absorbed by the non-skin side portion of the second non-grooved region, where the density of the superabsorbent polymer is lower. Therefore, the dispersion ability of the excreted liquid in the non-skin side portion of the upper core is improved. Furthermore, the excreted liquid that has moved to the non-skin side portion of the second non-grooved region is absorbed by the skin side portion of the second non-grooved region and retained by the superabsorbent polymer, thus suppressing rewetting of the excreted liquid onto the skin side surface of the upper core.

[0089] In such absorbent articles, the second groove is a groove that is recessed from the non-skin side surface of the upper core toward the skin side in the thickness direction.

[0090] According to this absorbent article, liquid excreted in the upper core can immediately fall into the space of the second groove in the upper core and be dispersed. Therefore, it is possible to prevent the excreted liquid from overflowing onto the skin-side surface of the upper core.

[0091] In such absorbent articles, when viewed in the thickness direction, the grooved area of ​​the lower core has a portion that overlaps with the second grooved area of ​​the upper core.

[0092] According to this absorbent article, a large amount of excretory fluid absorbed in the second groove region of the upper core can be drawn into the groove region of the lower core. Therefore, the leakage of excretory fluid onto the skin-side surface of the upper core can be suppressed.

[0093] In such absorbent materials,

[0094] The lower core has a slit in the central portion of the area of ​​the lower core that abuts against the wearer's crotch area in the width direction.

[0095] The slit penetrates the lower core layer in the thickness direction.

[0096] The slit is elongated in the longitudinal direction, and

[0097] When viewed from the thickness direction

[0098] The slits in the lower core overlap with those in the upper core, and

[0099] In at least a portion of the slit in the lower core, the slit does not overlap with the second groove region of the upper core.

[0100] According to this absorbent article, the slit makes the central portion of the absorbent core more easily deformable in the width direction to protrude towards the skin, thereby improving the fit between the absorbent core and the wearer's crotch area. Furthermore, a portion of the absorbent core with the slit overlaps with the second non-grooved area of ​​the upper core, thus preventing excessive reduction in the stiffness of the absorbent core and suppressing shape loss.

[0101] In such absorbent materials,

[0102] The elastic element is positioned in the area that rests against the wearer's crotch area.

[0103] The elastic member stretches and contracts in the longitudinal direction.

[0104] When viewed in the thickness direction, the entire slit of the lower core does not overlap with the second groove area of ​​the upper core, and

[0105] When viewed in the thickness direction, the slit has a portion that overlaps with the elastic member.

[0106] According to this absorbent article, the slit and the grooved areas of the upper core do not overlap in the thickness direction, thus reducing the likelihood of excreted fluid moving from the upper core to the slit and inhibiting the accumulation of excreted fluid in the slit. Furthermore, the deformation of the absorbent core protruding towards the skin due to the slit of the lower core is facilitated by an elastic member. Therefore, the fit between the absorbent core and the wearer's crotch area is improved, and the curved portion of the lower core's slit further inhibits the accumulation of excreted fluid.

[0107] In such absorbent materials,

[0108] The lower core has a pair of side slits in the side portion of the area of ​​the lower core that abuts against the crotch area of ​​the wearer.

[0109] The pair of side slits penetrate the lower core in the thickness direction.

[0110] The groove region is positioned at a location that is located on the outside of the pair of side slits in the width direction and at least partially overlaps with the pair of side slits in the longitudinal direction.

[0111] According to this absorbent article, due to the side slits of the lower core, the side portion of the absorbent core in the width direction rises to the skin side, making it easier to conform to the wearer's upper leg joint. Due to the presence of the grooved area, the rising side portion of the absorbent core in the width direction has greater flexibility, allowing it to easily deform along the wearer's upper leg joint and improving fit.

[0112] In such absorbent materials,

[0113] The lower core has a slit in the central portion of the area where it abuts against the wearer's crotch area in the width direction.

[0114] The slit penetrates the lower core layer in the thickness direction.

[0115] The slit is elongated in the longitudinal direction.

[0116] The groove region is elongated in the predetermined direction, which is the longitudinal direction.

[0117] At a position located rearward in the longitudinal direction relative to the slit

[0118] The lower core has a region in which the non-grooved area is continuous from one end to the other in the width direction, and

[0119] The rear end of the upper core in the longitudinal direction is located in the region where the non-grooved region is continuous.

[0120] According to this absorbent material, the lower core can easily bend longitudinally along the rear end of the upper core. Therefore, the rear end portion of the lower core can easily follow the wearer's hip area, improving the fit of the absorbent core.

[0121] In such absorbent materials,

[0122] The lower core extends outward from the longitudinal end of the upper core in the longitudinal direction, and

[0123] The groove area is provided in the portion of the lower core that extends outward from the upper core in the longitudinal direction.

[0124] According to this absorbent article, the excreted fluid received by the lower core from the upper core can be dispersed to the longitudinal end portion of the lower core (which does not overlap with the upper core in the thickness direction). The end portion of the lower core has high flexibility due to the grooved area, which allows it to easily conform to the wearer's lower abdominal and hip areas.

[0125] The following description will use adult underwear-style diapers as an example of absorbent articles according to this embodiment. However, absorbent articles are not limited to this; other examples of absorbent articles include adhesive-back diapers, baby diapers, lightweight incontinence pads, sanitary napkins, etc.

[0126] Basic structure of underwear-style diapers 1

[0127] Figure 1 This is a schematic three-dimensional diagram of a disposable underwear-style diaper 1 (hereinafter also referred to as "diaper"). Figure 2 This is a schematic plan view of diaper 1 in an unfolded and stretched state when viewed from the skin side. Figure 3 It is along Figure 2 A schematic cross-sectional view taken from line aa.

[0128] The unfolded state of diaper 1 refers to a state in which the connecting portion 2 (described later) between the front waist portion 21 and the back waist portion 22 has been pulled apart and diaper 1 has been unfolded. The stretched state of diaper 1 refers to a state in which diaper 1 has been stretched to eliminate wrinkles. Specifically, in this state, diaper 1 is stretched until there is no influence from the elastic members of diaper 1, and the dimensions of the constituent members of diaper 1 are the same as or close to the dimensions of these members themselves.

[0129] The diaper 1 in its panty-like state has a vertical direction, a width direction, and a thickness direction, and includes an absorbent body 10 and an outer member 20. In the vertical direction, the side where the waist opening BH of the diaper 1 is located is the upper side, and the opposite side is the lower side. The longitudinal direction of the diaper 1 in its unfolded state corresponds to the vertical direction of the diaper 1 in its panty-like state, and also corresponds to the longitudinal direction of the absorbent body 10. In the longitudinal direction, the side that contacts the wearer's abdominal area is the front side, and the side that contacts the wearer's buttock area is the back side. Furthermore, in the thickness direction, the side that contacts the wearer's skin is the skin side, and the opposite side is the non-skin side.

[0130] The external component 20 is arranged on the non-skin side of the absorbent body 10 and includes a front waist portion 21, a back waist portion 22, and a crotch portion 23. The diaper 1 in the unfolded state is folded approximately at the center position in the longitudinal direction, and the two end portions of the front waist portion 21 and the back waist portion 22 in the width direction are connected by welding or similar means to form a pair of connecting portions 2, thereby obtaining the diaper 1 in an underwear-shaped state.

[0131] Multiple waist elastic members 211 and 221 (e.g., elastic cords) extending in the width direction are arranged on the front waist portion 21 and the rear waist portion 22, and are spaced apart in the vertical direction (longitudinal direction). Additionally, multiple leg elastic members 212 and 222 (e.g., elastic cords) extending along the leg opening LH are arranged in the front waist portion 21 and the rear waist portion 22. The waist elastic members 211 and 221 and the leg elastic members 212 and 222 are fixed in a stretched state between two layers of sheet material (e.g., non-woven fabric sheet).

[0132] The crotch portion 23 is made of a sheet of material (e.g., a non-woven fabric sheet) connecting the front waist portion 21 and the back waist portion 22. However, the outer member 20 is not required to include the crotch portion 23.

[0133] The absorbent body 10 includes: an absorbent core 30 for absorbing and retaining excreted liquids; a liquid-permeable top sheet 11 (e.g., a nonwoven fabric sheet or a porous resin membrane) disposed on the skin side of the absorbent core 30; a liquid-permeable intermediate sheet 12 disposed between the top sheet 11 and the absorbent core 30; a liquid-impermeable back sheet 13 (e.g., a resin membrane) disposed on the non-skin side of the absorbent core 30; a pair of side sheets 14 (e.g., hydrophobic nonwoven fabric sheets) disposed on the side portions in the width direction of the absorbent body 10; a leak-proof wall elastic member 15; a leg elastic member 16; a crotch elastic member 17; and a cover sheet 18 covering the crotch elastic member 17 from the non-skin side.

[0134] Although not shown in detail, the side panel 14 folds from the side portion of the non-skin-side surface of the back panel 13 in the width direction toward the side portion of the skin-side surface of the top panel 11 in the width direction. The leak-proof elastic member 15 and the leg elastic member 16 are fixed to the side panel 14 in a stretched state in the longitudinal direction. The leak-proof elastic member 15 is arranged at the edge end portion of the side panel 14, which folds inward in the width direction toward the skin-side surface of the top panel 11. The leg elastic member 16 is arranged on the side portion of the absorbent body 10 in the width direction. The crotch elastic member 17 is arranged in the central portion of the absorbent body 10 in both the longitudinal and width directions, and is fixed between the back panel 13 and the cover panel 18 in a stretched state in the longitudinal direction.

[0135] Although the basic structure of the panty-style diaper 1 has been described above, the structure of the panty-style diaper 1 is not limited to the above description.

[0136] Absorbent body 10 (absorbent core 30)

[0137] First Embodiment

[0138] Figure 4 This is a plan view of the upper core 31 viewed from the skin side in the thickness direction. Figure 5 This is a plan view of the lower core 32 as seen from the skin side in the thickness direction. Figure 6 This is a plan view of the upper core 31 and the lower core 32 in an overlapping state when viewed from the skin side in the thickness direction. Figure 7 This is a schematic cross-sectional view of a portion of the upper core 31 and the lower core 32. Figure 8A It is along Figure 6 A schematic cross-sectional view taken from line II in the middle. Figure 8B It is along Figure 6 A schematic cross-sectional view taken from line II-II. Figure 9A This is a schematic 3D diagram of chip 39. Figure 9B This is an illustrative view of a variant of the arrangement of chip 39. Figure 10A , 10B 11A and 11B are illustrative views of variations of grooves 35 and 36.

[0139] The absorbent core 30 has a two-layer structure, including an upper core 31 and a lower core 32 disposed on the non-skin side in the thickness direction relative to the upper core 31. The upper core 31 and the lower core 32 include liquid absorbent fibers 33 (pulp fibers, cellulose absorbent fibers, etc.) and superabsorbent polymer 34 (SAP).

[0140] The upper core 31 and the lower core 32 have an hourglass shape in planar shape, with the central portion in the longitudinal direction contracting inward in the width direction. For example... Figure 6As shown, the lower core 32 is larger than the upper core 31, and the upper core 31 is arranged to fit within the outer peripheral edge of the lower core 32.

[0141] The upper core 31 has a groove 35 (second groove), wherein a portion of the upper core 31 is recessed in the thickness direction. When viewed along the thickness direction, the upper core 31 has: a grooved region A1 (second grooved region) in which the groove 35 is provided; and a non-grooved region A2 (second non-grooved region) in which no groove is provided. The groove 35 is elongated in the longitudinal direction of the diaper 1. In the upper core 31, a plurality of grooves 35 extending in the longitudinal direction are spaced apart in the width direction and also spaced apart in the longitudinal direction. Furthermore, the groove 35 in the first embodiment is an upward-facing groove, which is recessed in the thickness direction from the skin-side surface of the upper core 31 toward the non-skin side.

[0142] The lower core 32 also has a groove 36, wherein a portion of the lower core 32 is recessed in the thickness direction. When viewed in the thickness direction, the lower core 32 has: a grooved region A3 in which the groove 36 is provided; and a non-grooved region A4 in which the groove 36 is not provided. However, unlike the groove 35 of the upper core 31, the groove 36 of the lower core 32 is a downward-facing groove, which is recessed in the thickness direction from the non-skin side surface of the lower core 32 towards the skin side. The groove 36 is elongated 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 the width direction and also spaced apart in the longitudinal direction.

[0143] Additionally, the lower core 32 has a central slit 37 (slit) penetrating the lower core 32 in the thickness direction, and a pair of side slits 38. The central slit 37 is a generally rectangular slit that extends in the longitudinal direction and is located in the central portion of the crotch area of ​​the diaper 1 in the width direction. The pair of side slits 38 are generally rectangular slits that extend in the longitudinal direction. The pair of side slits 38 are positioned outside the central slit 37 in the width direction and overlap at least a portion of the central slit 37 in the longitudinal direction. The central slit 37 is longer than the side slits 38 in both the width and longitudinal directions. Furthermore, when viewed along 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.

[0144] It should be noted that the crotch area of ​​diaper 1 is the area assumed to be in contact with the wearer's crotch. Specifically, in the vertical direction, the area below the connecting portion 2 of diaper 1 (on the inner side in the longitudinal direction) is defined as the crotch area. Alternatively, the crotch area can be the area where diaper 1 is unfolded and stretched ( Figure 2 The central region when it is divided into three parts in the longitudinal direction.

[0145] Here, when the upper core 31 and the lower core 32 are divided into two parts in the thickness direction, the parts located on the skin side are skin-side parts 311 and 321, and the parts located on the non-skin side are non-skin-side parts 312 and 322. Specifically, the skin-side parts 311 and 321 and the non-skin-side parts 312 and 322 are separated by an imaginary line that extends horizontally from the center C in the thickness direction in the thickest part of the non-groove regions A2 and A4.

[0146] 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-grooved region A2. For this reason, the excreted fluid draining from the skin-side surface of the upper core 31 flows more readily into the groove region A1 (which is a low-SAP region) compared to the non-grooved region A2. Therefore, the excreted fluid is dispersed longitudinally along the groove region A1, which extends in the longitudinal direction.

[0147] In particular, the groove 35 of the upper core 31 is an upward-facing groove. Therefore, the skin-side portion 311 in the groove region A1 is the spatial 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 low (zero or close to zero). Since the upper core 31 directly receives the excreted liquid, by making the groove 35 an upward-facing groove, the excreted liquid excreted on the skin-side surface of the upper core 31 can immediately fall into the spatial portion of the groove 35 and disperse in the longitudinal direction. Therefore, even if a large amount of excreted liquid is excreted, the overflow of excreted liquid on the skin-side surface of the upper core 31 can be suppressed.

[0148] Furthermore, if the groove 35 of the upper core 31 is a slit penetrating in the thickness direction, the drained liquid moves downward before dispersing along the groove region A1, and is partially absorbed in a portion of the lower core 32. The extent to which the drained liquid disperses from this partially absorbed portion is limited, and the drained liquid cannot be absorbed over a large area of ​​the lower core 32. The same applies to the upper core 31; the drained liquid moves to the lower core 32 before being dispersed in the upper core 31, therefore the drained liquid cannot be absorbed over a large area of ​​the upper core 31.

[0149] To address this issue, the groove 35 of the upper core 31 in this embodiment is a groove 35 (recessed portion) in which a portion of the upper core 31 is recessed in the thickness direction. For this reason, it is possible to prevent the drained liquid from immediately moving from the groove region A1 to the lower core 32, and the drained liquid can be dispersed along the groove region A1 over a large area of ​​the upper core 31.

[0150] And, as Figure 6As shown, some grooved regions A1 of the upper core 31 are provided in the areas where, when viewed in the thickness direction, the upper core 31 and the lower core 32 overlap each other. For this reason, the lower core 32 can receive and absorb the drained liquid dispersed along these grooved regions A1 of the upper core 31. Therefore, the drained liquid can also advantageously be dispersed in the lower core 32, and the drained liquid is absorbed over a large area of ​​the lower core 32. Furthermore, after the lower core 32 becomes saturated, the drained liquid is dispersed and absorbed over a large area of ​​the upper core 31.

[0151] It should be noted that the lower core 32 in this embodiment has a central slit 37. In this case, it is preferable to provide groove regions A1 in such portions of the upper core 31: these portions overlap in the thickness direction with portions of the lower core 32 in which the central slit 37 is not arranged. According to this configuration, the lower core 32 can receive and absorb the discharged liquid dispersed along such groove regions A1.

[0152] Furthermore, since the groove 35 of the upper core 31 in this embodiment differs from the slit, the lower core 32 is not exposed to the skin side in the groove region A1. For this reason, it prevents the excretory fluid absorbed in the portion of the lower core 32 facing the upper core 31 from flowing back and contacting the user's skin. Additionally, the skin-side portion 311 in each non-grooved region A2 of the upper core 31 is a high-SAP region. For this reason, the excretory fluid absorbed by the skin-side portion 311 of the non-grooved region A2 is reliably retained by the superabsorbent polymer 34. Therefore, it prevents rewetting of the excretory fluid on the skin-side surface of the upper core 31.

[0153] As described above, in the absorbent core 30 of this embodiment, the discharged liquid can be well dispersed in the upper core 31 and the lower core 32, and the absorption capacity is improved. Therefore, even if the liquid is repeatedly discharged, the overflow or leakage of the discharged liquid can be suppressed. In addition, the rewetting of the discharged liquid can also be suppressed.

[0154] In addition, Figure 7In the upper core 31, the bottom portion of the groove 35 is located at the boundary between the skin-side portion 311 and the non-skin-side portion 312, but this is not limited; the bottom portion of the groove 35 can be located shallower or deeper than the boundary. Additionally, the high SAP region of the skin-side portion 311 of the non-groove region A2 of the upper core 31 can extend to the non-skin side, beyond the bottom portion of the groove 35 (or, if the groove 35 is a downward-facing groove, beyond the ceiling portion of the groove 35). Furthermore, a portion of the non-skin-side portion 312 in the groove region A1 (i.e., a portion of the bottom portion or the ceiling portion of the groove 35) can be a high SAP region. If a portion of the bottom portion (or ceiling portion) of the groove 35 is a high SAP region, excretory fluid is less likely to be drawn into the bottom portion (or ceiling portion) of the groove 35. For this reason, excretory fluid is more easily dispersed above (or below) the bottom portion of the groove 35, improving the ability of excretory fluid to disperse in the upper core 31. This also applies similarly to the lower core 32.

[0155] Furthermore, it is preferable that the average density of the superabsorbent polymer 34 in the non-skin side portion 312 of the non-grooved region A2 is lower than the average density of the superabsorbent polymer 34 in the skin side portion 311 of the non-grooved region A2. According to this configuration, excretory fluid moving downwards from the skin side portion 311 of the grooved region A1 (towards the non-skin side portion 312) easily moves to the non-skin side portion 312 of the non-grooved region A2 (which is a low-SAP region). For this reason, the ability of the excretory fluid to disperse in the upper core 31 is improved. For example, the excretory fluid flows in the non-grooved region A2, which is arranged alongside the grooved region A1 in the width direction, and is also dispersed in the width direction. The excretory fluid further dispersed in the upper core 31 is then received by the lower core 32, thus the excretory fluid is absorbed over a larger area in the lower core 32. However, the present invention is not limited to the above-described structure. 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.

[0156] Furthermore, the excreted fluid that has moved to the non-skin side portion 312 of the non-grooved region A2 then moves to the lower core 32 and is also drawn up by the skin side portion 311 of the non-grooved region A2. Since the skin side portion 311 of the non-grooved region A2 is a high-SAP region, the drawn-up excreted fluid is reliably retained by the superabsorbent polymer 34. Therefore, rewetting of the excreted fluid on the skin side surface of the upper core 31 can be prevented.

[0157] If the groove 35 of the upper core 31 is an upward-facing groove, then the superabsorbent polymer 34 and the liquid absorbent fibers are arranged in the non-skin side portion 312 of the groove region A1. In this case, it is preferable that the average density of the superabsorbent polymer 34 in the non-skin side portion 312 of the groove region A1 is lower than the average density of the superabsorbent polymer 34 in the skin side portion 311 of the non-groove region A2.

[0158] According to this structure, the excreted fluid that has flowed into the groove region A1 (space portion) of the skin-side portion 311 of the upper core 31 can easily move (downward) to the non-skin-side portion 312 of the groove region A1 (which is a low-SAP region). In other words, the fluid permeability of the groove region A1 is improved. For this reason, even with repeated excretion, the superabsorbent polymer 34 that has absorbed the excreted fluid can be prevented from inhibiting the fluid permeability of the groove region A1.

[0159] Furthermore, if the groove 35 of the upper core 31 is an upward-facing groove, it is preferable that the average density of the liquid-absorbing fibers in the non-skin side portion 312 of the non-groove region A2 is higher than the average density of the liquid-absorbing fibers in the non-skin side portion 312 of the groove region A1. According to this configuration, due to the capillary effect, the excreted liquid that has moved to the non-skin side portion 312 of the groove region A1 can easily move to the non-skin side portion 312 of the non-groove region A2. For this reason, the ability of the excreted liquid to disperse in the upper core 31 is improved. Additionally, the excreted liquid dispersed in the upper core 31 is received by the lower core 32 and absorbed over a larger area.

[0160] Furthermore, in this embodiment, the upper core 31 and the lower core 32 each have thin fiber layers 313 and 323 on their skin-side surfaces, respectively. Fiber layers 313 and 323 are composed of liquid-absorbing fibers 33 and do not contain superabsorbent polymers 34. Fiber layers 313 and 323 facilitate the dispersion of excreted fluid in the planar direction on the skin-side surfaces of the upper core 31 and the lower core 32. Therefore, the ability of excreted fluid to disperse in the upper core 31 and the lower core 32 is improved. However, it is also possible for the upper core 31 and / or the lower core 32 to not have fiber layers 313 and 323. Additionally, the thickness of fiber layers 313 and 323 is relatively low. For this reason, the difference in average density of the superabsorbent polymer 34 between the skin-side portions 311 and 321 (including portions of fiber layers 313 and 323) and the non-skin-side portions 312 and 322 (excluding portions of fiber layers 313 and 323) of the upper core 31 and the lower core 32 has no effect.

[0161] Additionally, although not shown, a thin fiber layer (a layer of liquid-absorbing fiber 33 without superabsorbent polymer 34) can be provided on the non-skin side surfaces of the upper core 31 and the lower core 32. In this case, the excreted liquid is also easily dispersed in the planar direction on the non-skin side surfaces of the upper core 31 and the lower core 32, further improving the ability of the excreted liquid to disperse in the upper core 31 and the lower core 32.

[0162] Furthermore, the comparison of the average density of the superabsorbent polymer 34 and the average density of the liquid absorbent fiber 33 in the absorbent core 30 can be performed using known methods. For example, the target absorbent core 30 is impregnated with liquid nitrogen, frozen, and then cut in the thickness direction with a razor to obtain a cross-section of the absorbent core 30 from the portion to be compared (e.g., grooved region A1 and non-grooved region A2). After the absorbent core 30 is allowed to return to room temperature, a cross-sectional image is obtained at 50x magnification using an electron microscope (e.g., a VE7800 manufactured by Keyence). Based on the cross-sectional image, the average density of the superabsorbent polymer 34 in the target portion can be visually compared. Similarly, the average density of the liquid absorbent fiber 33 in the target portion can also be visually compared based on the cross-sectional image. Furthermore, the number of superabsorbent polymers 34 and the number of liquid absorbent fibers 33 per unit area can be counted and compared in the cross-sectional image.

[0163] As another example, the target absorber core 30 is frozen and then cut to obtain a cross-section of the absorber core 30 from the portion to be compared. The average density of the superabsorbent polymer 34 can then be compared based on an image obtained by irradiating the cross-section with X-rays. In areas where the superabsorbent polymer 34 particles overlap significantly, the X-ray transmittance is lower. For this reason, in the X-ray image, areas with high average density of the superabsorbent polymer 34 are visually perceived as dark, and the target portion can be compared based on its brightness / darkness. Furthermore, the weight of the superabsorbent polymer 34 and the weight of the liquid absorbent fiber 33 can be obtained using the measurement method described in Japanese Patent Application No. 2018-542962, and the weight can be converted to density for comparison.

[0164] As described above, by forming an absorbent core 30 with a two-layer structure, the amount of excreted fluid that can be absorbed by the diaper 1 can be increased. However, if the excreted fluid has difficulty moving from the upper core 31 to the lower core 32, the excreted fluid may accumulate in the thickness direction in the space between the upper core 31 and the lower core 32. In this case, the amount of excreted fluid absorbed by the lower core 32 is reduced, and the absorbency of the lower core 32 cannot be effectively utilized.

[0165] Therefore, in the lower core 32, it is also preferable that the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the groove region A3 is lower than the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the non-grooved region A4. It is also preferable that at least some of the groove regions A3 of the lower core 32 are located in regions where the upper core 31 and the lower core 32 overlap when viewed in the thickness direction.

[0166] According to this construction, excretory fluid that moves along the thickness direction to the boundary between the upper core 31 and the lower core 32 is easily absorbed by the grooved region A3 (a low-SAP region) of the skin-side portion 321 of the lower core 32. For this reason, the accumulation of excretory fluid at the boundary between the upper core 31 and the lower core 32 can be suppressed, and the excretory fluid can be moved to the lower core 32. Therefore, the lower core 32 can reliably absorb excretory fluid, and the amount of excretory fluid that can be absorbed by the diaper 1 can be prevented from decreasing. On the other hand, the skin-side portion 321 of the non-grooved region A4 of the lower core 32 is a high-SAP region. For this reason, the excretory fluid absorbed by the skin-side portion 321 of the non-grooved region A4 is reliably retained by the superabsorbent polymer 34, and rewetting of the excretory fluid can be suppressed.

[0167] Furthermore, the excretory fluid absorbed in the groove region A3 easily moves into the space below it (non-skin side portion 322). Then, the excretory fluid is dispersed in the longitudinal direction along the space of the groove region A3. For this reason, the excretory fluid dispersed in the upper core 31 is further dispersed in the lower core 32, and the excretory fluid is absorbed over a larger area of ​​the lower core 32.

[0168] Furthermore, the groove 36 of the lower core 32 is a groove 36 (recessed portion) in which a portion of the lower core 32 is recessed in the thickness direction. For this reason, unlike the case where the groove 36 is a slit penetrating in the thickness direction, it is possible to prevent the excreted liquid from accumulating in the groove 36. In other words, even in the portion in which the liquid-absorbing fibers 33 and the superabsorbent polymer 34 are arranged, the excreted liquid can be dispersed.

[0169] Furthermore, if the groove 36 of the lower core 32 is a downward-facing groove, then the ability of liquid to penetrate downwards (in the space) within the groove region A3 is stronger. Therefore, the excretory liquid can be drawn to the non-skin side portion 322 of the lower core 32 and then dispersed, allowing for effective utilization of the lower core 32. Additionally, since the groove 36 of the lower core 32 is a downward-facing groove, rather than a slit, and because the space portion (recessed portion) of the groove 36 does not exist on the skin side surface of the lower core 32, the speed at which the excretory liquid moves from the upper core 31 to the lower core 32 can be suppressed to an appropriate level. Therefore, the excretory liquid is dispersed in the upper core 31 before moving to the lower core 32.

[0170] In addition, similar to the upper core 31, it is also preferable in the lower core 32 that the average density of the superabsorbent polymer 34 in the non-skin side portion 322 of the non-groove region A4 is lower than the average density of the superabsorbent polymer 34 in the skin side portion 321 of the non-groove region A4.

[0171] According to this configuration, in the non-skin side portion 322 of the lower core 32, the excreted liquid that has been dispersed longitudinally along the space of the groove 36 can easily move to the non-skin side portion 322 of the non-groove region A4 (these regions are low SAP regions). For this reason, the dispersion ability of the excreted liquid in the lower core 32 is further improved. In addition, the excreted liquid that has moved to the non-skin side portion 322 of the non-groove region A4 is drawn up by the skin side portion 321 of the non-groove region A4. Since the skin side portion 321 of the non-groove region A4 is a high SAP region, the drawn-up excreted liquid is reliably retained, and rewetting of the excreted liquid can be suppressed.

[0172] 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 outward in the longitudinal direction from the longitudinal end 31a of the upper core 31. In the portion of the lower core 32 that extends outward from the upper core 31 in the longitudinal direction, the discharged liquid will not accumulate at the boundary with the upper core 31, but it is preferable that a groove region A3 of the lower core 32 is also provided in this portion.

[0173] According to this structure, excreted fluid can be dispersed to areas of the lower core 32 that do not overlap with the upper core 31 in the thickness direction. Furthermore, the longitudinal end portion of the lower core 32 is elastic due to the groove 36, allowing it to deform easily. Therefore, the lower core 32 can easily conform to the wearer's lower abdominal and hip areas.

[0174] Furthermore, it is preferable that, when viewed in the thickness direction, 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 (excluding the two grooves 35A that overlap with the central slit 37) overlap with the grooves 36 of the lower core 32.

[0175] In the upper core 31, more excretory fluid flows downward (towards the non-skin side) through the grooved region A1 compared to the non-grooved region A2. For this reason, if the grooved regions A1 of the upper core 31 and A3 of the lower core 32 are aligned, a large amount of excretory fluid passing through the grooved region A1 of the upper core 31 can be received by the grooved region A3 of the lower core 32, drawn into the lower core 32 (the space 322 on the non-skin side), and dispersed. Therefore, the accumulation of excretory fluid at the boundary between the upper core 31 and the lower core 32 can be further suppressed. It should be noted that in this embodiment, the groove 35 of the upper core 31 and the groove 36 of the lower core 32 that overlap with it have the same shape and arrangement, but this is not a limitation, and the groove 35 of the upper core 31 and the groove 36 of the lower core 32 only need to at least partially overlap.

[0176] Furthermore, preferably, in at least a portion of the lower core 32, the average density of the superabsorbent polymer 34 in the skin-side portion 321 of a given 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 the upper core 31 facing that given region. According to this configuration, the velocity of excretory fluid moving from the upper core 31 to the lower core 32 can be suppressed to an appropriate level. Therefore, the excretory fluid is dispersed in the upper core 31 before moving to the lower core 32.

[0177] Specifically, in the absorbent core 30 of the first embodiment, most of the grooved region A1 of the upper core 31 overlaps with the grooved region A3 of the lower core 32, and most of the non-grooved region A2 of the upper core 31 overlaps with the non-grooved region A4 of the lower core 32. As described above, the non-grooved region A4 of the skin-side portion 321 of the lower core 32 is a high SAP region, and the non-grooved region A2 of the non-skin-side portion 312 of the upper core 31 facing the non-grooved region A4 is a low SAP region, thereby achieving the above-mentioned relationship. On the other hand, both the grooved region A3 of the skin-side portion 321 of the lower core 32 and the grooved region A1 of the non-skin-side portion 312 of the upper core 31 facing the grooved region A3 are low SAP regions. For this reason, it is preferable that the average density of the superabsorbent polymer 34 in the grooved region A3 of the skin-side portion 321 of the lower core 32 is higher than the average density in the grooved region A1 of the non-skin-side portion 312 of the upper core 31.

[0178] Furthermore, the lower core 32 has a central slit 37 extending in the longitudinal direction, located in the central portion of the area that abuts against the wearer's crotch area in the width direction. For this reason, the lower core 32 and the upper core 31 that overlaps with it are bent along the central slit 37 (in the longitudinal direction). As a result, the central portion of the absorbent core 30 in the width direction deforms to protrude towards the skin relative to the side portions, and can easily conform to the wearer's crotch area.

[0179] Additionally, the groove region A1 of the upper core 31 has a portion that overlaps with the central slit 37 when viewed in the thickness direction. Figure 6 (Recess 35A). In the portion of the absorbent core 30 with the central slit 37, the ability to absorb excreted liquid is reduced, but the excreted liquid can be dispersed in the recessed region A1 of the upper core 31 that overlaps with the central slit 37. In particular, it is preferable that the longitudinal end portions of these recessed regions A1 of the upper core 31 extend outward from the central slit 37 in the longitudinal direction. According to this configuration, the excreted liquid can move to the portion that does not overlap with the central slit 37. Therefore, the overflow of excreted liquid in the crotch area can be suppressed.

[0180] However, the present invention is not limited to the above-described structure. The portion of the absorbent core 30 with the central slit 37 has lower stiffness. For this reason, it is possible to construct a structure in which, when viewed in the thickness direction, at least a portion of the central slit 37 of the lower core 32 does not overlap with the groove region A1 (groove 35) of the upper core 31. For example, as Figure 10A As shown in the variant, such a configuration is possible where the entire area of ​​the central slit 37 does not overlap with the grooved area A1 of the upper core 31. According to this configuration, it is possible to prevent the portion of the absorbent core 30 with lower stiffness due to the central slit 37 from having even lower stiffness due to the grooved area A1. Furthermore, it is possible to suppress the absorbent core 30 from losing its shape. Consequently, the absorbent core 30 exhibits longer absorption performance. Additionally, excreted fluid tends to accumulate in the central slit 37. Therefore, since the non-grooved area A2 is provided as the area of ​​the upper core 31 that overlaps with the central slit 37, the skin-side portion 311 is a high SAP region, and the movement of excreted fluid towards the central slit 37 can be suppressed. Thus, the accumulation of fluid in the central slit 37 can be suppressed.

[0181] Furthermore, preferably, the groove 35 of the upper core 31 does not extend to the outer peripheral edge of the upper core 31, and the groove 36 of the lower core 32 does not extend to the outer peripheral edge of the lower core 32. With this configuration, shape loss of the upper core 31 and the lower core 32 can be suppressed. In addition, it can prevent the discharge liquid from dispersing to the outer peripheral edges of the upper core 31 and the lower core 32.

[0182] Additionally, as described above, the diaper 1 is provided with a crotch elastic member 17 that stretches and contracts longitudinally in the area against the wearer's crotch. Figure 6 As shown, preferably, when viewed in the thickness direction, the central slit 37 and the groove region A1 of the upper core 31 have a portion that overlaps with the crotch elastic member 17.

[0183] According to this construction, the deformation of the absorbent core 30 protruding towards the skin due to the central slit 37 is facilitated by the stretching and contraction of the crotch elastic member 17. Furthermore, due to the presence of the groove region A1, the absorbent core 30 becomes flexible and can easily deform to conform to the wearer's crotch. This deformation is also facilitated by the stretching and contraction of the crotch elastic member 17. Therefore, the fit between the diaper 1 and the wearer is improved.

[0184] In addition, such as Figure 10A As shown in the variant, 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. According to this configuration, the skin-protruding deformation of the absorbent core 30 caused by the central slit 37 is facilitated by the crotch elastic member 17, and a portion of the central slit 37 of the lower core 31 is bent to inhibit the accumulation of excretory fluid.

[0185] Furthermore, in the portion that overlaps with the central slit 37 of the lower core 32 in the longitudinal direction, the side end of the upper core 31 in the width direction is located outside the central slit 37 in the width direction and inside the side end of the lower core 32 in the width direction. For this reason, the side portion of the lower core 32 in the width direction is prone to bending along the side end of the upper core 31 in the width direction (in the longitudinal direction). In other words, the side portion of the lower core 32 in the width direction is prone to rising to the skin side.

[0186] Furthermore, the lower core 32 has a pair of side slits 38 on the corresponding side of the central slit 37 in the width direction. The position of the side slits 38 in the width direction is substantially the same as the position of the side ends of the upper core 31 in the width direction. For this reason, the side portions of the lower core 32 in the width direction also tend to rise to the skin side due to the presence of the pair of side slits 38. Therefore, in the crotch area, the central portion of the absorbent core 30 in the width direction is easily deformed to protrude to the skin side, and the side portions in the width direction tend to rise to the skin side and easily deform into a W-shaped cross-section. For this reason, the diaper can more easily fit the wearer's crotch.

[0187] Furthermore, preferably, in the width direction, on the outer side of the central slit 37 of the lower core 32, in the region where the upper core 31 and the lower core 32 overlap, at least one of a groove 35 of the upper core 31 or a groove 36 of the lower core 32 is provided. According to this configuration, the high-rigidity region where the two cores 31 and 32 overlap is given flexibility due to the grooves 35 and 36, and can be easily deformed, thereby making the diaper more easily conform to the wearer's crotch area.

[0188] Furthermore, preferably, the groove region A3 (groove 36A) of the lower core 32 is positioned outward in the width direction relative to the side slit 38 of the lower core 32, and at least partially overlaps with the side slit 38 in the longitudinal direction. According to this configuration, the side portion of the lower core 32 that has risen to the skin side has greater flexibility. For this reason, the side portion of the lower core 32 in the width direction can easily deform along the wearer's upper leg joint, and the fit is also improved.

[0189] However, the present invention is not limited to the above-described structure, and it is also possible for the lower core 31 to not have a central slit 37 and / or a side slit 38.

[0190] Furthermore, preferably, the grooves 36 of the lower core 32 are arranged to be separate from the outer peripheral edges of the central slit 37 and the side slits 38. This configuration can suppress the loss of shape of the lower core 32.

[0191] It should be noted that, preferably, the width (length in the width direction) of the central slit 37 and the side slits 38 is greater than the width (length in the width direction of the main grooves 351 and 361 and the length in the longitudinal direction of the secondary grooves 352 and 362) of the upper core 31 and the lower core 32. According to this configuration, the absorbent core 30 can easily deform into a W shape due to the presence of the central slit 37 and the side slits 38. On the other hand, by not making the width of the grooves 35 and 36 too large, the absorbent core 30 can be prevented from losing its shape. Preferably, the width of the central slit 37 and the side slits 38 is, for example, about 7 mm to 50 mm, so that the absorption performance does not decrease too much. The width of the grooves 35 and 36 is preferably, for example, about 1 mm to 8 mm. Furthermore, the length in the longitudinal direction of the central slit 37 and the side slits 38 is sufficient to abut against the wearer's crotch, for example, about 50 to 300 mm, or preferably about 100 to 250 mm.

[0192] Furthermore, the groove 35 of the upper core 31 and the groove 36 of the lower core 32 each include: main grooves 351 and 361 that are elongated in the longitudinal direction; and secondary grooves 352 and 362 that extend from the main grooves 351 and 361 in the width direction. Specifically, a plurality of secondary grooves 352 and 362 extend from the main grooves 351 and 361 in the width direction at intervals in the longitudinal direction. A plurality of such main grooves 351 and 361 are arranged at certain intervals in both the width and longitudinal directions.

[0193] Due to the secondary grooves 352 and 362, the liquid discharged on the skin-side surface of the upper core 31 and the discharged liquid drawn into the non-skin-side portion 322 (space portion) of the lower core 32 can be dispersed not only in the longitudinal direction but also in the width direction. Therefore, the dispersion ability of the discharged liquid in the upper core 31 and the lower core 32 can be further improved.

[0194] Furthermore, by having the absorbent core 30 have a two-layer structure, the amount of excreted liquid that can be absorbed increases, but the absorbent core 30 becomes more rigid and less prone to deformation. However, in this embodiment, the upper core 31 and the lower core 32 have grooves 35 and 36. In particular, the grooves 35 and 36 are provided in the areas where the upper core 31 and the lower core 32 overlap and have higher rigidity. For this reason, the absorbent core 30 is given flexibility and can easily deform along the wearer's body.

[0195] Furthermore, grooves 35 and 36 include not only main grooves 351 and 361 extending in the longitudinal direction, but also secondary grooves 352 and 362 extending in the width direction. For this reason, the upper core 31 and lower core 32 can be easily bent not only in the longitudinal direction, but also easily bent in the width direction at the secondary grooves 352 and 362. For this reason, the absorbent core 30 can be easily bent in the longitudinal direction along the portion extending from the wearer's lower abdominal area to their hip area.

[0196] 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. In addition, 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 secondary grooves 352 of the upper core 31 and the secondary grooves 362 of the lower core 32 also overlap. Therefore, the overlapping areas of the upper core 31 and the lower core 32 can more easily bend along the grooves 35 and 36 in both the longitudinal and width directions, and are more easily deformed to fit the wearer's body.

[0197] Furthermore, the longitudinal positions of the adjacent sub-grooves 352 and 362 in the width direction are aligned with each other. For this reason, the upper core 31 and the lower core 32 can be easily bent in the width direction at the sub-grooves 352 and 362, and can easily deform along the wearer's body.

[0198] In addition, such as Figure 6 As shown, in the region located rearward in the longitudinal direction relative to the central slit 37, the upper core 31 and lower core 32 have regions A21, A41, and A42, wherein the non-grooved regions A2 and A4 are continuous from one end to the other in the width direction. Thus, regions A21, A41, and A42, which are continuous in the width direction and do not include grooves 35 and 36, are provided in the rear end portions of the upper core 31 and lower core 32. Therefore, the upper core 31 and lower core 32 can easily bend in the longitudinal direction along such regions (at the longitudinal ends of grooves 35 and 36). In other words, the bending of the upper core 31 and lower core 32 in the longitudinal direction is not easily hindered by the grooves 35 and 36 extending in the longitudinal direction. For this reason, the rear end portions of the upper core 31 and lower core 32 easily conform to the wearer's rounded hip area.

[0199] In addition, such as Figure 6 As shown, the rear end 32a of the lower core 32 is located behind the rear end 31a of the upper core 31, and the rear end 31a of the upper core 31 is located in a continuous non-grooved region A42 in the width direction of the lower core 32. For this reason, the rear end portion of the lower core 32 can easily bend in the longitudinal direction along the rear end 32a of the upper core 31. Therefore, the rear end portion of the lower core 32 can easily conform to the rounded hip area of ​​the wearer.

[0200] Furthermore, as described above, the rear end portion of the absorbent core 30 can be easily bent in the longitudinal direction, thus preventing the W-shaped deformation of the crotch area of ​​the absorbent core 30 (deformation caused by the central slit 37 and the side slits 38) from being transmitted to the rear position of the absorbent core 30. Therefore, the rear end portion of the absorbent core 30 can easily conform to the wearer's hip area.

[0201] Furthermore, the region in which the upper core 31 and the lower core 32 do not overlap (the region including only the lower core 32) has low stiffness and high flexibility when viewed in the thickness direction. For this reason, although not shown, in the region including only the lower core 32, the width of the groove 36 of the lower core 32 (specifically, the length of the main groove 361 in the width direction and the length of the secondary groove 362 in the longitudinal direction) can be smaller than in the region where the upper core 31 and the lower core 32 overlap. According to this configuration, shape loss of the lower core 32 can be suppressed.

[0202] Furthermore, when viewed in the thickness direction, the boundary portion (the outer peripheral edge of the upper core 31) between the overlapping areas of the upper core 31 and the lower core 32 and their non-overlapping areas tends to become the bending point of the absorber core 30, but also tends to become the starting point of shape loss of the absorber core 30. Therefore, it is preferable that the groove regions A1 and A3 are not provided in the boundary portion, and particularly preferably that the groove region A3 of the lower core 32 is not provided. With this configuration, shape loss of the absorber core 30 can be suppressed.

[0203] like Figure 8A and 8B As shown, a sheet-like chip 39 (e.g., thin cotton paper or nonwoven fabric) that is permeable to liquid can be provided in the boundary portion between the upper core 31 and the lower core 32. An example of the sheet-like chip 39 is shown below. Figure 9A As shown, a nonwoven fabric sheet is treated with an uneven surface to have protrusions 391 and recesses 392 extending in the longitudinal direction. Due to the protrusions and recesses of the core 39, excreted liquid can be dispersed in the longitudinal direction, improving its dispersion ability within the upper core 31 and lower core 32. It should be noted that the protrusions and recesses of the core 39 are not limited to extending in the longitudinal direction, but can also extend in the width direction or other directions. Furthermore, the protrusions and recesses of the core 39 increase the amount of storage space for excreted liquid. Therefore, even if a large amount of excreted liquid is excreted, it can be temporarily stored in the storage space of the core 39, thereby preventing overflow onto the skin-side surface of the upper core 31. Additionally, although not shown, the protrusions 391 and recesses 392 extending in the longitudinal direction can be arranged intermittently in the core 39. In this case, the excreted liquid can also be dispersed in the width direction at the intervals between the protrusions and recesses.

[0204] Furthermore, by arranging the aforementioned chip 39 at the boundary between the upper core 31 and the lower core 32 (by arranging the protruding and recessed surfaces of the chip 39 to face the non-skin side surface of the upper core 31), the excreted liquid can be better dispersed on the non-skin side surface of the upper core 31. However, the chip 39 is not limited to a sheet with protrusions and recesses.

[0205] Furthermore, the chip 39 is not limited to being arranged at the boundary between the upper chip 31 and the lower chip 32. For example, as... Figure 9B As shown, the encapsulated chip 39 can be arranged to wrap around the lower core 32 from the non-skin side surface towards the skin side surface. According to this configuration, shape loss of the lower core 32 can be suppressed by the encapsulated chip 39. Additionally, the encapsulated chip 39 can be arranged outside the boundary portion between the upper core 31 and the lower core 32 (e.g., where the lower core 32 is removed). Figure 9B (The portion other than p1 to p2). According to this configuration, an adhesive for adhering the packing chip 39 and absorbent core 30 in the boundary portion between the upper core 31 and the lower core 32 is unnecessary, and the ability of liquid to permeate from the upper core 31 to the lower core 32 is improved. Furthermore, the packing chip 39 can be arranged from the skin-side surface to the non-skin-side surface to... Figure 9B The layers of the upper core 31 and lower core 32 are wrapped around the lower core 32 in opposite directions. In this case, if the lower core 32 is to be completely surrounded, portions of the wrapping chips 39 overlap. However, since the overlapping areas are arranged on the non-skin side surface of the lower core 32, liquid can move more smoothly from the upper core 31 to the lower core 32 compared to the case where the overlapping areas are arranged between the upper core 31 and the lower core 32, thus inhibiting the accumulation of excretory liquid. Alternatively, the wrapping chips 39 can be arranged in a portion of the upper core 31 or in its periphery, or the wrapping chips 39 may not be arranged on the absorbent core 30.

[0206] 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... Figures 4 to 6 Examples are shown in the text. For example, in... Figure 10B In the absorbent core 30, grooves 35B and 36B provided in the side portion of the front end portion of the upper core 31 in the width direction are inclined inward toward the longitudinal center in the width direction. For this reason, the front end portion of the absorbent core 30, which rises from the narrowest part of the lower core 32, can be easily deformed into an inverted triangular cup shape, thereby wrapping around the lower abdominal area of ​​the wearer and improving the fit of the diaper 1.

[0207] Additionally, for example, such as Figure 11A As shown, secondary grooves 352 and 362 extend from the main grooves 351 and 361 in the central portion of the absorber core 30 along the longitudinal direction, but secondary grooves 352 and 362 are not provided in the end portions of the absorber core 30 along the longitudinal direction. Furthermore, the end portion of the lower core 32 in the longitudinal direction is a non-grooved region A4. As described above, the area ratio of grooved regions A1 and A3 can be smaller in the longitudinal end portions of the upper core 31 and the lower core 32 than in the central portion. With this configuration, shape loss of the absorber core 30 can be suppressed.

[0208] Additionally, for example, such as Figure 11B As shown, grooves 35 and 36 can extend to the two longitudinal ends of the upper core 31 and the lower core 32. According to this configuration, excreted liquid can be dispersed over a greater distance in the longitudinal direction. In this case, continuous non-grooved areas A22 and A43 in the width direction can be positioned behind the central slit 37, so that the rear portion of the absorbent core 30 follows the wearer's hip area (…). Figure 11B), and although not shown, grooves 35 and 36 can extend continuously from the longitudinal front end of the upper core 31 and the longitudinal rear end of the lower core 32.

[0209] Furthermore, the groove 35 of the upper core 31 and the groove 36 of the lower core 32 are not limited to having a predetermined length in the longitudinal direction, but can also be grooves extending in another direction (such as the width direction). Additionally, the groove 35 of the upper core 31 and the groove 36 of the lower core 32 can be grooves extending in mutually different directions. Furthermore, the groove 35 of the upper core 31 and the groove 36 of the lower core 32 can be configured to not overlap completely in the thickness direction. Furthermore, the groove 35 of the upper core 31 and the groove 36 of the lower core 32 do not necessarily have sub-grooves 352 and 362. Additionally, it is possible to construct a structure in which, when viewed in the thickness direction, groove regions A1 and A3 are not located in the areas where the upper core 31 and the lower core 32 do not overlap.

[0210] Second Embodiment

[0211] Figure 12 This is a schematic cross-sectional view of the absorbent core 30 according to the second embodiment. The lower core 32 of the second embodiment is the same as the lower core 32 of the first embodiment. Furthermore, similar to the upper core 31 of the first embodiment, the upper core 31 of the second embodiment has grooves 35 (upward-facing grooves) recessed from the skin-side surface to the non-skin side. However, in the second embodiment, the superabsorbent polymer 34 is uniformly distributed throughout the entire upper core 31 (excluding the portion excluding the fiber layer 313). Specifically, the average density of the superabsorbent polymer 34 is equal across the portions of the upper core 31, and the difference in this average density is smaller than the difference in the average density of the superabsorbent polymer 34 between the portions of the lower core 32 (e.g., the grooved region A3 and non-grooved region A4 of the skin-side portion 321).

[0212] In this situation, the excreted fluid on the skin-side surface of the upper core 31 can immediately fall into the space of the groove 35 of the upper core 31 and be dispersed. Since the superabsorbent polymer 34 is uniformly distributed in the upper core 31, even with repeated excretion, the movement of the fluid is not easily hindered by the superabsorbent polymer 34 that has absorbed the excreted fluid, and the upper core 31 has good permeability to the fluid. For this reason, while the excreted fluid is dispersed in the upper core 31, it moves in the thickness direction to the boundary between the upper core 31 and the lower core 32. The excreted fluid that has moved to the boundary is drawn into the interior through the groove region A3 (low SAP region) of the skin-side portion 321 of the lower core 32, and is subsequently further dispersed by the groove region A3 (space) of the non-skin-side portion 322.

[0213] Therefore, in the case where the upper core 31, in which the superabsorbent polymer 34 is uniformly distributed, has grooves 35, the grooves 35 can be Figure 12 The upward-facing groove shown can also be a downward-facing groove (not shown). In the case of a downward-facing groove, the excreted liquid that passes through the groove region A1 of the upper core 31 and moves to the non-skin side portion 312 can be dispersed in the space of the groove 35.

[0214] Third Embodiment

[0215] Figure 13 This is a schematic cross-sectional view of the absorbent core 30 according to the third embodiment. The lower core 32 of the third embodiment is the same as the lower core 32 of the first embodiment. In addition, the upper core 31 of the third embodiment does not have the groove 35, and the superabsorbent polymer 34 is uniformly distributed throughout the upper core 31 (in the portion except for the fiber layer 313).

[0216] In this case, the excreted fluid on the skin-side surface of the upper core 31 is carried into the interior of the upper core 31 and dispersed in the planar direction while moving to the boundary between the upper core 31 and the lower core 32 in the thickness direction. If a fiber layer 313 is provided on the skin-side surface of the upper core 31, the excreted fluid is dispersed in the planar direction on the skin-side surface of the upper core 31. Since the superabsorbent polymer 34 is uniformly distributed in the upper core 31, even with repeated excretion, the movement of the fluid is not easily hindered by the superabsorbent polymer 34 that has absorbed the excreted fluid, and the upper core 31 has good fluid permeability. The excreted fluid that has moved to the boundary between the upper core 31 and the lower core 32 is drawn into the interior through the groove region A3 (low SAP region) of the skin-side portion 321 of the lower core 32, and is subsequently dispersed by the groove region A3 (space portion) of the non-skin-side portion 322.

[0217] Fourth embodiment

[0218] Figure 14A and 14B This is a schematic cross-sectional view of the absorbent core 30 according to the fourth embodiment. Unlike the lower core 32 of the first embodiment, the groove 36 of the lower core 32 of the fourth embodiment is an upward-facing groove. In this case, in the skin-side portion 321 of the lower core 32, the groove region A3 is a space, and the average density of the superabsorbent polymer 34 in the groove region A3 is lower than the average density of the superabsorbent polymer 34 in the non-groove region A4. Excreted liquid from the upper core 31 falls into the space of the groove 36 in the skin-side portion 321 of the lower core 32 and disperses in the longitudinal direction. This makes it possible to suppress the accumulation of excreted liquid at the boundary between the upper core 31 and the lower core 32 in the thickness direction. The dispersion ability of the excreted liquid in the lower core can be improved.

[0219] If the groove 36 of the lower core 32 is an upward-facing groove, it is preferable that, similar to the upper core 31 in the first embodiment, the average density of the superabsorbent polymer 34 in the non-skin side portion 322 of the groove region A3 is 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 permeability of the groove region A3 of the lower core 32 from being hindered by the superabsorbent polymer 34 that has absorbed the excreted liquid. Furthermore, it is preferable that the average density of the liquid-absorbing fibers 33 in the non-skin side portion 322 of the non-groove region A4 of the lower core 32 is higher than the average density of the liquid-absorbing fibers 33 in the non-skin side portion 322 of the groove region A3. Therefore, due to the capillary effect, the excreted liquid that has moved to the non-skin side portion 322 of the groove region A3 is more easily moved to the non-skin side portion 322 of the non-groove region A4, further improving the ability of the excreted liquid to disperse in the lower core.

[0220] Even if the groove 36 of the lower core 32 is an upward-facing groove, the groove 35 of the upper core 31 can also be an upward-facing groove. Figure 14A ) or downward-facing groove ( Figure 14B Alternatively, the upper core 31 described in the second or third embodiment can be used.

[0221] In addition, such as Figure 14B As shown, because the grooves 35 (downward-facing grooves) of the upper core 31 and 36 (upward-facing grooves) of the lower core 32 are aligned, a larger space can temporarily store the excreted fluid that has passed through the skin-side portion 311 of the upper core 31, and the stored excreted fluid can be dispersed along the grooves 35 and 36. For this reason, even if a large amount of fluid is excreted, it can prevent the excreted fluid from overflowing onto the skin-side surface of the upper core 31.

[0222] Furthermore, if the groove 35 of the upper core 31 is a downward-facing groove, the upper core 31 can easily deform, causing the central portion in the width direction to protrude towards the skin relative to the side portions. This promotes deformation of the lower core 32 due to the presence of the central slit 37, allowing the absorbent core 30 to easily conform to the wearer's crotch area. On the other hand, if the groove 36 of the lower core 32 is an upward-facing groove, the lower core 32 can easily deform, causing the central portion in the width direction to protrude towards the non-skin side relative to the side portions. This makes deformation along the rounded hip area more likely.

[0223] Fifth Embodiment

[0224] Figure 15 This is a schematic plan view of the diaper 1 according to the fifth embodiment when viewed from the skin side in its unfolded and stretched state. Figure 16 It is along Figure 15 A schematic cross-sectional view taken from section AA in the image. Figure 17 This is a plan view of the upper core 31 and lower core 32 in an overlapping state when viewed from the non-skin side in the thickness direction. Figure 18A This is a plan view of the upper core 31 when viewed from the skin side in the thickness direction. Figure 18B This is a plan view of the lower core 32 when viewed from the non-skin side in the thickness direction. Figure 19 This is a plan view of the absorbent core 30 in the fifth embodiment, viewed from the non-skin side in the thickness direction.

[0225] like Figure 16 As shown, the lower core 32 of the fifth embodiment has a groove 36 (downward-facing groove) recessed from the non-skin side surface of the lower core 32 along the thickness direction toward the skin side, but does not have a central slit 37 and a pair of side slits 38. However, the present invention is not limited to the above-described structure, and it is also possible to provide slits (e.g., side slits 38) in the region of the lower core 32 where the groove region A3 is not provided.

[0226] like Figure 17 As shown, the absorbent core 30 has a "central portion in the width direction" and a pair of "side portions in the width direction", which are defined by dividing the maximum width of the absorbent core 30 into three equal parts in the width direction. In addition, the absorbent core 30 has a "front portion 30F" located in the longitudinal direction in front of the product centerline CL, and a "rear portion 30B" located in the longitudinal direction in rear of the product centerline CL.

[0227] The product centerline CL (centerline) is the line that guides the diaper 1 when it is in an unfolded or stretched state. Figure 15 The absorbent core 30 is divided into two equal parts in the longitudinal direction. Furthermore, the center of the absorbent core 30 in the longitudinal direction is not limited to being aligned with the product centerline CL; it can also deviate from the product centerline CL. In other words, the absorbent core 30 can be biased towards the front or back of the diaper 1. In this case, the front portion 30F and the back portion 30B have different lengths in the longitudinal direction.

[0228] The rear portion 30B of the absorbent core 30 has a region obtained by dividing its maximum length (the length from the product centerline CL to the rearmost end of the absorbent core 30) into three equal parts in the longitudinal direction. The central region obtained by this division will be referred to as the "rear first region 30B1", the region in front of the rear first region 30B1 will be referred to as the "rear second region 30B2", and the region behind the rear first region 30B1 will be referred to as the "rear third region 30B3".

[0229] Similarly, the front portion 30F of the absorber core 30 has a region obtained by dividing the maximum length (the length from the product centerline CL to the foremost end of the absorber core 30) into three equal parts in the longitudinal direction. The central region obtained by this division will be called the "front first region 30F1", the region behind the front first region 30F1 will be called the "front second region 30F2", and the region in front of the front first region 30F1 will be called the "front third region 30F3".

[0230] In other words, in the following description, the rectangular area defined by the maximum width and maximum length of the absorber core 10 is divided into a front region and a rear region along the longitudinal direction at the product centerline CL. The front and rear regions of the absorber core 30 are also each divided into nine regions.

[0231] It should be noted that in the fifth embodiment, the panty-style diaper 1 is described as an example of an absorbent article, but the absorbent article according to the fifth embodiment is also applicable to other absorbent articles, such as adhesive diapers or absorbent pads. When applied to adhesive diapers or absorbent pads, the product centerline is specific when the diaper is unfolded in the longitudinal direction, and the absorbent core is as follows... Figure 17 The diagram shows the division.

[0232] As described in the first embodiment, the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the groove region A3 in the lower core 32 is lower than the average density of the superabsorbent polymer 34 in the skin-side portion 321 of the non-grooved region A4. For this reason, excretory fluid from the upper core 31 is easily absorbed from the groove region A3 (which is a low-SAP region) into the lower core 32. Then, the excretory fluid is dispersed longitudinally along the space of the groove region A3. For this reason, the accumulation of excretory fluid at the boundary between the upper core 31 and the lower core 32 can be suppressed. By allowing the excretory fluid to flow smoothly from the upper core 31 into the lower core 32, the situation where the excretory fluid is not completely absorbed and flows outside the surface of the diaper 1 and leaks out can be prevented. Furthermore, by dispersing the excretory fluid, the lower core 32 can be effectively utilized over a large area in the surface direction.

[0233] In particular, when the groove 36 of the lower core 32 is a downward-facing groove, the ability of liquid to penetrate downwards (into the space) within the groove region A3 is higher. Therefore, the excreted liquid can be drawn to the non-skin side portion of the lower core 32, then dispersed, and the lower core 32 can be effectively utilized. It should be noted that the groove can be an upward-facing groove, as in the groove 36 of the lower core 32 in the fourth embodiment. In this case, although the excreted liquid from the upper core 31 falls into the space of the groove 36 and is dispersed, the excreted liquid can be absorbed into the lower core 32 from the three surfaces (bottom and a pair of side surfaces) forming each groove 36. Therefore, the accumulation of excreted liquid at the boundary between the upper core 31 and the lower core 32 can be suppressed.

[0234] Furthermore, compared with the first embodiment Figure 7 Similar to the absorbent core 30 shown, it is preferable that the groove 36 of the lower core 32 is not a groove compressed in the thickness direction, and the unit area weight (g / m²) of the lower core 32 (liquid absorbent fiber 33 and superabsorbent polymer 34) is... 2 The temperature is lower in the grooved region A3 than in the non-grooved region A4. Due to this configuration, the drained liquid from the upper core 31 flows more easily into the grooved region A3 and is more readily absorbed from the grooved region A3 into the lower core 32.

[0235] Note the unit area weight (g / m²) of the lower core 32 in the grooved region A3 and the non-grooved region A4. 2 The comparison can be made using known methods. For example, the lower core 32 can be frozen by immersing it in liquid nitrogen, and then cut along its thickness direction with a razor to obtain a cross-section of the lower core 32, which includes the parts to be compared (grooved region A3 and non-grooved region A4). The lower core 32 can then be returned to room temperature, and the cross-sectional image can be observed using an electron microscope to visually compare the amount of material in the grooved region A3 and non-grooved region A4, or to count and compare the number of material layers.

[0236] Furthermore, as an example of a method for manufacturing a lower core 32 (absorbent core 30) in which the weight per unit area of ​​the recessed region A3 is lower than that of the non-recessed region A4, the material constituting the lower core 32 can be applied to a patterned plate, the bottom surface of which has protrusions corresponding to the recessed region A3. Additionally, the weight per unit area and average density of the material can be controlled by adjusting the amount of material (liquid absorbent fiber 33 and superabsorbent polymer 34) supplied to the patterned plate.

[0237] As described above, excreted fluid from the upper core 31 is more easily absorbed into the lower core 32 from the grooved region A3. However, in many cases, the portion of the absorbent core 30 with the grooved region A3 has a thinner thickness and lower weight per unit area, thus making it more prone to rewetting of the diaper 1 surface. Furthermore, since the skin-side portion 321 of the lower core 32 in this embodiment is a low SAP region, rewetting from the lower core 32 to the upper core 31 is likely to occur, posing a risk of rewetting of the diaper 1 surface.

[0238] Therefore, in the absorbent core 30 of the fifth embodiment, the value obtained by dividing the area of ​​the groove region A3 of the lower core 32 in the central portion of the rear first region 30B1 in the width direction by the area of ​​the central portion of the rear first region 30B1 is set to be less than the value obtained by dividing the area of ​​the groove region A3 of the lower core 32 in the central portion of the front first region 30F1 in the width direction by the area of ​​the central portion of the front first region 30F1. Specifically, as Figure 17 As shown, in the central part of the rear first region 30B1 in the width direction, only one main groove 361 is provided that is longer in the longitudinal direction than in the width direction, while four main grooves 361 are provided in the central part of the front first region 30F1 in the width direction.

[0239] In the absorbent core 30, the central portion of the rear first region 30B1 in the width direction is the area that easily bears the body weight when the wearer is in a sitting or lying position. For this reason, by reducing the area ratio of the groove 36 in the central portion of the rear first region 30B1 in the width direction, the amount of rewetting of the liquid discharged from the groove region A3 can be reduced even if a large amount of body weight is applied to the rear first region 30B1.

[0240] On the other hand, compared to the rear portion 30B, the front portion 30F of the absorbent core 30 is the area that comes into contact with the wearer's excretion source, and is also the area where excretory fluid is more easily excreted, and is the area where the wearer is less likely to bear body weight when in a sitting or other position. In particular, compared to the front second region 30F2 that contacts the wearer's crotch and the front third region 30F3 that is more likely to come into close contact with the wearer due to the elastic members 211, 221, etc. of the waist of the diaper 1, the front first region 30F1 is less likely to bear the wearer's body weight. To this end, by increasing the area ratio of the groove 36 in the central portion of the front first region 30F1 in the width direction, the large amount of excretory fluid excreted by the wearer is less likely to accumulate at the boundary between the upper core 31 and the lower core 32 after passing through the upper core 31, and is quickly absorbed into the lower core 32 from the groove region A3. In particular, when the wearer is male, the front first area 30F1 is more readily accessible to the wearer's excretory source, allowing the lower core 32 to absorb excretory fluid more effectively. This prevents excretory fluid from being completely absorbed by the upper core 31 and leaking beyond the surface of the diaper 1. Furthermore, since body weight is less likely to be applied to the central portion of the front first area 30F1 in the width direction, rewetting is less likely to occur.

[0241] Additionally, the preferred average unit area weight (g / m²) of the lower core 32 is... 2 Overall, it is higher than the average unit area weight (g / m²) of the upper core 31. 2 In this situation, the absorption and retention capacity of the upper core 31 is relatively small. For this reason, by increasing the area ratio of the groove 36 in the central portion of the front first region 30F1 in the width direction as described above, a large amount of excreted liquid discharged from the excretion source can be rapidly moved from the upper core 31 to the lower core 32. Therefore, even if the average unit area weight of the upper core 31 is low, it can effectively prevent the excreted liquid from leaking out due to incomplete absorption by the upper core 31.

[0242] However, the present invention is not limited to the above-described structure, and may also have a structure in which the average unit area weight (g / m²) of the lower core 32 is... 2 Overall, it is equal to or lower than the average unit area weight (g / m²) of the upper core 31. 2 It should be noted that the comparison of average weight per unit area can be performed using known methods. For example, the weight per unit area is preferably obtained by separating and removing the upper core 31 and the lower core 32 from the diaper 1, and then measuring the weight (g) and external area (m²) of cores 31 and 32. 2 ), and calculate the weight per unit area based on these.

[0243] Furthermore, the absorbent core 30 of the fifth embodiment also has a configuration in which, similar to the absorbent core 30 in the described embodiments, the upper core 31 and the lower core 32 overlap each other, and the groove region A3 is at least partially disposed in the overlapping portion including the upper core 31 and the lower core 32. In other words, the groove region A3 is disposed in the region where the upper core 31 and the lower core 32 overlap, where the absorbent core 30 has a relatively high weight per unit area and a high retention force for discharged liquid. For this reason, even if a large amount of discharged liquid is absorbed by the portion of the absorbent core 30 in which the groove region A3 is disposed, rewetting from the groove region A3 can be suppressed more than with a single-layer absorbent core.

[0244] It should be noted that Figure 17 An absorber core 30 is shown, wherein the upper core 31 is shorter than the lower core 32 in both the width and longitudinal directions. However, the invention is not limited thereto. For example, it can be configured such that the lower core 32 is shorter than the upper core 31 in both the width and longitudinal directions, and it can also be configured such that the upper core 31 is longer (or shorter) than the lower core 32 in the width direction, and the upper core 31 is shorter (or longer) than the lower core 32 in the longitudinal direction. Furthermore, in... Figure 17 In this configuration, the lower core 32 extends further in the longitudinal direction than the upper core 31 on both sides. However, the invention is not limited thereto. For example, there may be a configuration in which the upper core 31 extends further in the longitudinal direction than the lower core 32 on both sides, or there may be a configuration in which the lower core 32 extends further in the longitudinal direction than the upper core 31 on one side of the longitudinal direction, and the upper core 31 extends further in the longitudinal direction than the lower core 32 on the other side of the longitudinal direction.

[0245] Furthermore, at the portion in contact with the discharge source, most of the discharge liquid not absorbed by the absorbent core 30 flows rearward in the longitudinal direction across the central portion in the width direction of the absorbent core 30. For this reason, the groove 36 of the lower core 32 is preferably located in the central portion in the width direction of the rear first region 30B1. However, this is the area where weight is more likely to be applied and rewetting is more likely to occur. In view of this, as Figure 17As shown, preferably, the portion of the lower core 32 located in the central part of the rear first region 30B1 in the width direction has a region with only one main groove 361, the length of which in the longitudinal direction is longer than its length in the width direction. In other words, preferably, there exists a region that does not include multiple main grooves 361 arranged side by side in the width direction. According to this configuration, the discharged liquid flowing from the portion in contact with the discharge source to the rear first region 30B1 passes through the upper core 31 and is 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 discharged liquid flowing out from the portion in contact with the discharge source can smoothly move from the upper core 31 to the lower core 32, thereby suppressing the leakage of the discharged liquid. In addition, the area ratio of the groove region A1 can be kept small, and the rewetting amount from the groove region A1 can be reduced.

[0246] and Figure 17 The difference is that such a construction is possible, in which multiple main grooves 361 are arranged side by side in the width direction in the front part of the central portion of the rear first region 30B1 (the portion close to the part in contact with the discharge source). In addition, the lower core 32 located in the central portion of the rear first region 30B1 in the width direction 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.

[0247] Additionally, the area ratio of the grooved regions A3 in the lower core 32 can be compared using known methods, and the number of grooved regions A3 can be observed. For example, when the absorbent core 30 (lower core 32) is separated from or exposed to the diaper 1 and the grooved regions A3 are visually observed, one can first... Figure 17 The absorption core 30 is divided as shown, and then the area ratio of the groove region A3 in the target part is visually compared and the number of groove regions A1 is checked. Alternatively, the groove region A3 (outline) can be determined from the image data obtained by taking pictures of the lower core 32 from the thickness direction, and the area of ​​the groove region A3 can be actually calculated using area calculation software or similar software.

[0248] Furthermore, as mentioned above, the X-ray transmission is reduced in the thicker portions of the superabsorbent polymer 34. Therefore, when the density (weight per unit area) of the superabsorbent polymer 34 in the grooved region A3 is less than that in the non-grooved region A4, the grooved region A3 can be determined based on an image obtained by irradiating the lower core 32 with X-rays along the thickness direction. In other words, there is a difference in brightness between the grooved region A3 and the non-grooved region A4 in the X-ray image. For this reason, the grooved region A3 can be visually determined based on the brightness of the X-ray image, and the area ratio of the grooved region A3 in the target area can be compared, as well as the number of grooved regions A3 can be checked. Alternatively, the X-ray image can be binarized to determine the grooved region A3 (outline), and the area of ​​the grooved region A3 can be actually calculated using area calculation software or similar software and compared.

[0249] Furthermore, most of the excreted liquid that is not absorbed by the absorbent core 30 at the point of contact with the excretion source flows rearward in the longitudinal direction across the central portion of the absorbent core 30 in the width direction. Therefore, it is preferable that the average unit area weight (g / m²) of the absorbent core 30 (upper core 31 and lower core 32) in the central portion of the rear first region 30B1 in the width direction is... 2 The average unit area weight (g / m²) is higher than that in the pair of side portions in the width direction of the first rear region 30B1. 2 Specifically, such as Figure 17 As shown, the upper core 31 and the lower core 32 are not disposed in the side portion (rectangular region) of the rear first region 30B1 in the width direction, but are disposed in the entire region of the central portion (rectangular region) in the width direction.

[0250] With this configuration, the central portion of the absorbent core 30 in the width direction of the rear first region 30B1 can absorb and retain a large amount of excretory fluid flowing out from the portion in contact with the excretion source. Furthermore, although the central portion of the rear first region 30B1 in the width direction is the part where the wearer's body weight is more likely to be applied, rewetting can be suppressed.

[0251] Furthermore, the drained liquid that is not absorbed by the central portion of the rear first region 30B1 of the absorber core 30 in the width direction tends to flow to the side portions in the width direction. For this reason, the portions of the lower core 32 located on the pair of side portions in the width direction of the rear first region 30B1 are preferably provided with main grooves 361. With this configuration, the drained liquid flowing to the side portions in the width direction and having passed through the upper core 31 is absorbed into the lower core 32 by the main grooves 361 and dispersed in the longitudinal direction. In other words, in the side portions of the absorber core 30 in the width direction, the drained liquid moves smoothly from the upper core 31 to the lower core 32, thereby suppressing leakage of the drained liquid, especially lateral leakage.

[0252] It should be noted that the average weight per unit area of ​​the absorbent core 30 can be compared using known methods. For example, the absorbent core 30 can be separated from the diaper 1, and as... Figure 17 As shown, the absorber core 30 is divided. Then, portions of the absorber core 30 located in the width direction of the central portion and the side portions in the width direction (including the stack of the upper core 31 and the lower core 32) in the rear first region 30B1 are cut out, and the weight (g) of each portion is measured. Then, the area a (m²) of the central portion in the width direction of the rear first region 30B1 is measured. 2 Then, the weight (g) of the central portion and the side portion in the width direction of the absorber core 30 located in the rear first region 30B1 is divided by the area a (m²). 2 To calculate the weight per unit area (g / m²) 2 ).

[0253] in addition, Figure 17 The planar shape of the upper core 31 shown is hourglass-shaped. The width of the upper core 31 is narrowest in the front second region 30F2, and its width in the longitudinal direction is wider on the front and rear sides than in the front second region 30F2. The narrow portion of the upper core 31 (front second region 30F2) is the portion that contacts or is close to the discharge source. For this reason, the groove region A3 of the lower core 32 is preferably located in the side portion in the width direction of the wider region behind the narrow portion of the upper core 31 in the longitudinal direction.

[0254] According to this configuration, similar to the description above, the discharged liquid flows rearward from the portion in contact with the discharge source through the central portion of the absorbent core 30 in the width direction, and the discharged liquid not absorbed by the central portion of the absorbent core 30 in the width direction flows to the side portion of the absorbent core 30 in the width direction. The discharged liquid passes through the upper core 31 and is then absorbed into the lower core 32 while being dispersed by the groove region A3. In other words, in the side portion of the absorbent core 30 in the width direction, the discharged liquid moves smoothly from the upper core 31 into the lower core 32, thereby suppressing leakage of the discharged liquid, especially lateral leakage.

[0255] In addition, such as Figure 18B As shown, preferably, in the longitudinal 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, the lower core 32 has a region in which the non-grooved region A4 is continuous from one end to the other in the width direction.

[0256] According to this configuration, the drained liquid through the upper core 31 is smoothly absorbed into the lower core 32 by the grooved region A3 in the front second region 30F2 (the region in contact with or near the drain source). In the non-grooved region A2 behind the front second region 30F2, i.e., in the region with a higher weight per unit area of ​​the lower core 32, the drained liquid is reliably absorbed and retained, and rewetting is suppressed. Furthermore, drained liquid that is not completely absorbed by the absorbent core 30 located in the front second region 30F2 and flows to the rearward side passes through the upper core 31 in the rear second region 30B2, and is then absorbed into the lower core 32 while being dispersed through the grooved region A3. This makes it possible to suppress leakage of the drained liquid.

[0257] Furthermore, preferably, the area of ​​the groove region A3 of the lower core 32 located in the central portion of the rear second region 30B2 in the width direction, divided by the area of ​​the central portion of the rear second region 30B2 in the width direction, is greater than the area of ​​the groove region A3 of the lower core 32 located in the central portion of the rear first region 30B1 in the width direction, divided by the area of ​​the central portion of the rear first region 30B1 in the width direction. Specifically, only one main groove 361 of the lower core 32, which is longer in the longitudinal direction than in the width direction, is provided in the central portion of the rear first region 30B1, while three main grooves 361 of the lower core 32 are provided in the central portion of the rear second region 30B2 in the width direction.

[0258] By increasing the area ratio of the grooved region A3 in the rear second region 30B2, which is closer to the area in contact with the excretion source, a large amount of excreted liquid flowing from the area in contact with the excretion source and through the upper core 31 can smoothly enter the lower core 32, and leakage of the excreted liquid can be suppressed. On the other hand, by reducing the area ratio of the grooved region A3 in the rear first region 30B1, which is more likely to bear the wearer's body weight, rewetting can be suppressed.

[0259] However, the present invention is not limited to the above-described structure, such as in Figure 19 In the variant shown, such a construction is possible, wherein the central portion of the rear second region 30B2 in the width direction has the same number (one in this case) of main grooves 361 as the central portion of the rear first region 30B1 in the width direction. For example, in the case of the wearer excreting a large amount of excretory fluid, such as Figure 17 As shown, preferably, a plurality of recessed regions A3 are provided in the portion of the lower core 32 located in the central part in the width direction of the second rear region 30B2. On the other hand, even if the wearer excretes a small amount of excretory fluid, Figure 19 As shown, the lower core 32 with fewer grooves A3 in the central part of the width direction of the second region 30B2 on the rear side can also suppress leakage of the drained liquid.

[0260] Furthermore, preferably, the number of main grooves 361 that are longer in the longitudinal direction than in the width direction is greater in the portion of the lower core 32 of the central part of the front first region 30F1 in the width direction than in the portion of the lower core 32 of the central part of the front second region 30F2 in the width direction. Figure 17 In the lower core 32, two main grooves 361 are provided in the front second region 30F2, and four main grooves 361 are provided in the front first region 30F1. Preferably, the area ratio of the groove region A3 of the lower core 32 is larger in the front first region 30F1 than in the front second region 30F2.

[0261] As described above, compared to the second front region 30F2 (which contacts the wearer's groin), the wearer's body weight is less likely to be applied to the first front region 30F1. For this reason, even with an increase in the number of main grooves 361, rewetting of excretory fluid can be suppressed. Furthermore, in the case of a male wearer, the area relatively located at the front is the part in contact with the source of excretion. Therefore, by increasing the number of main grooves 361 in the first front region 30F1, a large amount of excretory fluid discharged from the source passes through the upper core 31 and is then rapidly absorbed into the lower core 32 by the numerous main grooves 361 and dispersed. Thus, leakage of excretory fluid can be suppressed.

[0262] Furthermore, in the central portion of the rear first region 30B1 and the central portion of the rear second region 30B2 in the width direction, a main groove 361 of the lower core 32 is provided along the center line, which divides the rectangular region into two parts in the width direction. According to this configuration, the excreted liquid flowing rearward from the portion in contact with the discharge source through the central portion of the absorbent core 30 in the width direction and through the upper core 31 easily flows into the groove region A3 of the lower core 32 and is easily absorbed into the lower core 32.

[0263] On the other hand, in the central portion of the front first region 30F1 and the central portion of the front second region 30F2 in the width direction, the main groove 361 of the lower core 32 is not located on the center line dividing the rectangular region into two parts in the width direction, but rather on both sides of the center line. With this configuration, the wearer's excretion source is less likely to be located at the main groove 351 of the lower core 32, and the weight per unit area of ​​the absorbent core 30 is adequately guaranteed in the area receiving the most excreted liquid. For this reason, rewetting can be effectively suppressed.

[0264] In addition, such as Figure 15 As shown, the diaper 1 has a pair of leak-proof wall portions 19 in two side portions in the width direction of the absorbent core 30 (absorbent body 10), which can rise to the skin side. Specifically, as Figure 16 As shown, the side panel 14 is folded back from the side portion of the non-skin side surface of the back panel 13 in the width direction to the side portion of the skin side surface of the top panel 11 in the width direction. The leak-proof wall elastic member 15 is fixed to the end portion in the width direction of the inner side of the folded side panel 14 while being stretched in the longitudinal direction.

[0265] In addition, such as Figure 15 As shown, the side panel 14 is connected to the skin-side surface of the top panel 11 via a first connecting portion 191 and a second connecting portion 192 on which an adhesive or similar substance is applied. The first connecting portion 191 extends from one end of the absorbent body 10 in the longitudinal direction to the other end in the longitudinal direction. The second connecting portion 192 is disposed at both ends in the longitudinal direction of the absorbent body 10 and is located inside the width direction of the first connecting portion 191 in the width direction. Therefore, in the side panel 14, the portion located inside the width direction of the first connecting portion 191 (rising support point) and the portion located inside the longitudinal direction of the second connecting portion 192 (rising support point) can rise to the skin side, and this portion serves as a leak-proof wall portion 19.

[0266] When the diaper 1 has a leak-proof wall portion 19, it is preferable that the lower core 32 has a grooved area A3, which is present in the diaper 1 in both unfolded and stretched states. Figure 15 When viewed along the thickness direction, it at least partially overlaps with the leak-proof wall portion 19. According to this structure, the drained liquid blocked by the leak-proof wall portion 19 and absorbed by the upper core 31 can be quickly absorbed from the groove region A3 into the lower core 32, and the leakage of drained liquid outside the leak-proof wall portion 19 can be suppressed.

[0267] Furthermore, in the area where the leak-proof wall portion 19 is provided, the wearer's skin contacts the side panel 14, rather than directly contacting the top panel 11. For this reason, even if rewetting occurs due to excreted fluid from the grooved area A3 that overlaps with the leak-proof wall portion 19 in the thickness direction, the wearer is less likely to feel this rewetting, and the comfort of the diaper 1 can be prevented from decreasing. Additionally, the leak-proof wall portion 19, which rises to the skin side due to the contraction of the leak-proof wall elastic member 15, readily acts as a cushioning material, thus reducing the likelihood of the wearer's body weight being applied to the portion where the leak-proof wall portion 19 is located. For this reason, even if the grooved area A3 is provided in the portion that overlaps with the leak-proof wall portion 19 in the thickness direction, rewetting can be suppressed.

[0268] In addition, such as Figure 16 As shown, when the upper core 31 also contains a superabsorbent polymer 34 similar to that in the lower core 32, it is preferable that the overall average density of the superabsorbent polymer 34 in the upper core 31 is higher than the overall average density of the superabsorbent polymer 34 in the lower core 32.

[0269] Compared to the excreted liquid present between the absorbent fibers, the excreted liquid retained in the superabsorbent polymer 34 is less prone to free movement and less likely to cause rewetting. Therefore, by increasing the average density of the superabsorbent polymer 34 in the upper core 31, the excreted liquid flowing back from the lower core 32 (particularly the groove region A3) to the upper core 31 can be reliably retained by the superabsorbent polymer 34 in the upper core 31. For this reason, even when the absorbent core 30 is subjected to the wearer's body weight, rewetting from the upper core 31 to the top sheet 11 can be suppressed.

[0270] 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 thereto. For example, the upper core 31 may have a groove 35 (upward-facing groove) that is recessed in the thickness direction from the skin-side surface of the upper core 31 to the non-skin side, or it may have a groove 36 (downward-facing groove) that is recessed in the thickness direction from the non-skin-side surface of the upper core 31 to the skin side.

[0271] When the upper core 31 has a recessed region A1, similar to the lower core 32, it is preferable that the area ratio of the recessed region A1 in the central portion of the upper core 31 located in the width direction of the rear first region 30B1 is relatively small. For example, it is preferable that the area ratio of the recessed region A1 in the central portion of the upper core 31 located in the width direction of the front first region 30F1 is smaller.

[0272] By providing a recessed region A1 in the upper core 31 located in the central portion of the front first region 30F1 in the width direction, the discharged liquid flowing from the portion in contact with the discharge source through the central portion of the absorbent core 30 in the width direction to the rear first region 30B1 can be absorbed into the absorbent core 30 by the recessed region A1 in the upper core 31. Therefore, leakage of the discharged liquid can be suppressed. However, by reducing the area ratio of the recessed region A1, rewetting of the discharged liquid can be suppressed.

[0273] On the other hand, the front first region 30F1 is the part that is in contact with or close to the source of excretion. Therefore, by increasing the area ratio of the groove region A1 of the upper core 31 in the central part of the width direction of the front first region 30F1, a large amount of excretory fluid discharged by the wearer can be quickly absorbed into the absorbent core 30 by the groove region A1 of the upper core 31, thereby suppressing the leakage of excretory fluid.

[0274] It should be noted that when viewing the absorbent core 30 along the thickness direction, the groove region A1 of the upper core 31 and the groove region A3 of the lower core 32 can be aligned with each other or offset relative to each other. If the positions are aligned, the excreted liquid absorbed from the groove region A1 of the upper core 31 can be quickly absorbed by the lower core 32 and dispersed by the groove region A3 of the lower core 32. On the other hand, when the positions of the groove regions A1 and A3 are offset relative to each other, the local decrease in the unit area weight of the portion of the absorbent core 30 in which the groove regions A1 and A3 are provided can be suppressed, and rewetting from the groove regions A1 and A3 can be suppressed.

[0275] Other implementation methods

[0276] Although embodiments of this disclosure have been described herein, these embodiments are merely for the purpose of facilitating understanding of the disclosure and should not be construed as limiting the disclosure in any way. Various changes or modifications may be made to the disclosure without departing from its essential points, and its equivalents are covered.

[0277] For example, the upper core 31 is not limited to an absorbent core obtained by molding liquid absorbent fibers 33 containing superabsorbent polymer 34 into a predetermined shape. The upper core 31 may be a SAP sheet in which the SAP layer is adhered to a hydrophilic sheet, or an air-laid sheet in which liquid absorbent fibers are formed into a sheet by an air-laying method, or a similar sheet.

[0278] Explanation of reference numerals in the attached figures

[0279] 1. (Underwear style) diaper (absorbent), 2. Connecting part,

[0280] 10 Absorbent body, 11 Top sheet, 12 Middle sheet, 13 Back sheet

[0281] 14 Side panels, 15 Leak-proof wall elastic component, 16 Leg elastic component,

[0282] 17. Crotch elastic member (elastic member); 18. Cover plate;

[0283] 20 External components, 21 Front waist section, 22 Rear waist section, 23 Crotch section

[0284] 211, 221 Waist elastic components; 212, 222 Leg elastic components.

[0285] 30 Absorbent core, 31 Upper core, 32 Lower core

[0286] 33 Liquid absorbent fiber, 34 Superabsorbent polymer,

[0287] Groove 35 (second groove), Groove 36

[0288] 37. Central slit (slit), 38. Side slit,

[0289] 39 packs of chips,

[0290] A1 is the grooved area (second grooved area), A2 is the non-grooved area (second non-grooved area).

[0291] A3 recessed area, A4 non-recessed area

Claims

1. An absorbent article having a longitudinal direction, a width direction, and a thickness direction, the absorbent article comprising an absorbent core, the absorbent core comprising an upper core and a lower core, the lower core overlapping the upper core in the thickness direction and disposed on the non-skin side relative to the upper core in the thickness direction. The lower core comprises a superabsorbent polymer and has a groove in the thickness direction of a portion thereof. The groove is recessed from the non-skin side surface of the lower core towards the skin side in the thickness direction and is elongated in a predetermined direction. When viewed in the thickness direction, the lower core has a grooved region in which the groove is provided and a non-grooved region in which the groove is not provided. When viewed in the thickness direction, at least a portion of the groove region is located in the area where the upper core and the lower core overlap. When the lower core is divided into two parts in the thickness direction, the average density of the superabsorbent polymer in the skin-side portion of the grooved region is lower than the average density of the superabsorbent polymer in the skin-side portion of the non-grooved region, wherein the skin-side portion is the portion located on the skin side and the non-skin-side portion is the portion located on the non-skin side. The upper core comprises a superabsorbent polymer and has a second groove in which a portion of the upper core is recessed in the thickness direction. The second groove is a groove recessed from the skin-side surface of the upper core towards the non-skin side in the thickness direction, and the second groove is elongated in the longitudinal direction. Viewed in the thickness direction, the upper core has: 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. When viewed along the thickness direction, at least a portion of the second groove region is disposed in the area where the upper core and the lower core overlap, and When the upper core is divided into two parts in the thickness direction, the average density of the superabsorbent polymer in the skin-side portion of the second grooved region is lower than the average density of the superabsorbent polymer in the skin-side portion of the second non-grooved region, wherein the skin-side portion is the portion located on the skin side, and the non-skin-side portion is the portion located on the non-skin side. 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, and the average density of the superabsorbent polymer in the groove region of the skin-side portion of the lower core is higher than the average density of the superabsorbent polymer in the groove region of the non-skin-side portion of the upper core.

2. The absorbent article according to claim 1, wherein, The absorbent core has a central portion in the width direction and a pair of side portions in the width direction. The central portion and the pair of side portions in the width direction are determined by dividing the maximum width of the absorbent core into three parts in the width direction. The absorbent core has a front portion located at the front of the product centerline in the longitudinal direction and a rear portion located at the rear of the product centerline in the longitudinal direction. The product centerline is the line that divides the absorbent article in its unfolded and stretched state into two parts in the longitudinal direction. The rear portion has a rear first region, which is a central region obtained by dividing the maximum length of the rear portion into three parts in the longitudinal direction. The front portion has a front first region, which is a central region obtained by dividing the maximum length of the front portion into three parts in the longitudinal direction. The value obtained by dividing the area of ​​the grooved region of the lower core in the central part of the width direction of the rear first region by the area of ​​the central part of the width direction of the rear first region is less than the value obtained by dividing the area of ​​the grooved region of the lower core in the central part of the width direction of the front first region by the area of ​​the central part of the width direction of the front first region.

3. The absorbent article according to claim 2, wherein, A portion of the lower core in the central part of the rear first region in the width direction has a region with only one groove, the groove being elongated in the longitudinal direction, the longitudinal direction being the predetermined direction.

4. The absorbent article according to claim 2 or 3, wherein, The average weight per unit area of ​​the absorber core is higher in the central portion of the rear first region in the width direction than in the pair of side portions of the rear first region in the width direction, and, Each of the lower core portions of a pair of side portions located in the width direction of the rear first region has an elongated groove in the longitudinal direction, the longitudinal direction being the predetermined direction.

5. The absorbent article according to claim 2 or 3, wherein, The rear portion has a rear second region located on the front side relative to the rear first region in the longitudinal direction. The front portion has a front second region located rearward relative to the front first region in the longitudinal direction, and The lower core has a region in which, in the longitudinal 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, the non-grooved region is continuous from one end to the other in the width direction.

6. The absorbent article according to claim 2 or 3, wherein, The rear portion has a rear second region located on the front side relative to the rear first region in the longitudinal direction, and The value obtained by dividing the area of ​​the grooved region of the lower core in the central part of the width direction of the second rear region by the area of ​​the central part of the second rear region is greater than the value obtained by dividing the area of ​​the grooved region of the lower core in the central part of the width direction of the first rear region by the area of ​​the central part of the width direction of the first rear region.

7. The absorbent article according to claim 2 or 3, wherein, The front portion has a front second region located rearward relative to the front first region in the longitudinal direction, and A portion of the lower core in the central part of the front first region in the width direction has more elongated grooves in the longitudinal direction than a portion of the lower core in the central part of the front second region in the width direction, wherein the longitudinal direction is the predetermined direction.

8. The absorbent article according to claim 2 or 3, wherein, The average weight per unit area of ​​the lower core is higher than that of the upper core.

9. The absorbent article according to any one of claims 1 to 3, wherein, The absorbent article further includes a pair of leak-proof wall portions in two side portions along the width of the absorbent core, the pair of leak-proof wall portions being capable of rising to the skin side, and When an absorbent article is viewed in its unfolded and stretched state in the thickness direction, the lower core has a grooved area that at least partially overlaps with the leak-proof wall portion.

10. The absorbent article according to any one of claims 1 to 3, wherein, The upper core comprises 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. The absorbent article according to any one of claims 1 to 3, wherein, The average density of superabsorbent polymers in the non-skin side portion of the non-groove region is lower than the average density of superabsorbent polymers in the skin side portion of the non-groove region.

12. The absorbent article according to any one of claims 1 to 3, wherein, The groove includes: The main groove is elongated in the predetermined direction, which is the longitudinal direction; and A secondary groove extending from the main groove in the width direction. Multiple main grooves are arranged side-by-side at intervals in the width direction, and Multiple secondary grooves extend from each main groove in the width direction and are positioned to be spaced apart in the longitudinal direction.

13. The absorbent article according to claim 1, wherein, The average density of superabsorbent polymers in the non-skin side portion of the second non-groove region is lower than the average density of superabsorbent polymers in the skin side portion of the second non-groove region.

14. The absorbent article according to claim 13, wherein, The lower core has a slit in the central portion of the area of ​​the lower core that abuts against the wearer's crotch area in the width direction. The slit penetrates the lower core layer in the thickness direction. The slit is elongated in the longitudinal direction, and When viewed in the thickness direction, the slit of the lower core overlaps with that of the upper core, and in at least a portion of the slit of the lower core, the slit does not overlap with the second groove region of the upper core.

15. The absorbent article according to claim 14, wherein, The elastic element is positioned in the area that rests against the wearer's crotch area. The elastic member stretches and contracts in the longitudinal direction. When viewed in the thickness direction, the entire slit of 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.

16. The absorbent article according to claim 1, wherein, The lower core has a pair of side slits in the side portion of the area of ​​the lower core that abuts against the crotch area of ​​the wearer. The pair of side slits penetrate the lower core in the thickness direction. The groove region is positioned at a location that is located on the outside of the pair of side slits in the width direction and at least partially overlaps with the pair of side slits in the longitudinal direction.

17. The absorbent article according to claim 1, wherein, The lower core has a slit in the central portion of the area where it abuts against the wearer's crotch area in the width direction. The slit penetrates the lower core layer in the thickness direction. The slit is elongated in the longitudinal direction. The groove region is elongated in the predetermined direction, which is the longitudinal direction. At a position located rearward in the longitudinal direction relative to the slit The lower core has a region in which the non-grooved area is continuous from one end to the other in the width direction, and The rear end of the upper core in the longitudinal direction is located in the region where the non-grooved region is continuous.

18. The absorbent article according to any one of claims 1 to 3, wherein, The lower core extends outward from the longitudinal end of the upper core in the longitudinal direction, and a groove area is provided in the portion of the lower core that extends outward from the upper core in the longitudinal direction.

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