Absorbent article

Abstract

The purpose of the present disclosure is to provide an absorbent article having excellent repeated absorbency of bodily fluids in a lying position, a standing position, and a sitting position.　An absorbent article (1) has a crotch region (CR) and is characterized in that: the absorbent article (1) includes an absorbent core (9) including pulp fibers (17) and superabsorbent polymer particles (19); the absorbent core (9) includes, in the crotch region (CR), a low-density part (21), a plurality of medium-density parts (27), and a high-density part (31); the low-density part (21) includes a through-hole extending in the longitudinal direction (L); each of the plurality of medium-density parts (27) has a base end (29a) connected to the low-density part (21) and a terminal end (29b), extends in the width direction (W), and has a density higher than that of the low-density part (21); and the high-density part (31) is in contact with each of the plurality of medium-density parts (27) and has a density higher than that of each of the plurality of medium-density parts (27).

Description

Absorbent articles 【0001】 This disclosure relates to absorbent articles. 【0002】 From the viewpoint of improving the rate of liquid absorption, studies have been conducted on absorbent articles having through holes in the absorbent core. For example, Patent Document 1 discloses an absorbent article having an absorbent body including a surface sheet, a back sheet, and an absorbent core disposed between the surface sheet and the back sheet, wherein the absorbent core has a through hole extending in the longitudinal direction in the center in the width direction of the absorbent body, and has a plurality of transverse grooves extending in the width direction of the absorbent body from the through hole, and an absorbent layer exists in at least the skin-contacting side of the internal space of the transverse grooves. 【0003】 Japanese Patent Publication No. 2013-255571 【0004】 Patent Document 1 does not disclose the absorbent article relating to this disclosure. Therefore, this disclosure aims to provide an absorbent article that exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions. 【0005】 The Disclosers have found an absorbent article having longitudinal, widthwise, and thicknesswise directions that are orthogonal to each other, and having a crotch region, wherein the absorbent article comprises an absorbent core containing pulp fibers and superabsorbent polymer particles, the absorbent core comprising a low-density portion, a plurality of medium-density portions, and a high-density portion in the crotch region, the low-density portion being composed of through holes extending along the longitudinal direction, each of the plurality of medium-density portions having a base end connected to the low-density portion and a terminal end, extending along the widthwise and having a higher density than the low-density portion, and the high-density portion being in contact with each of the plurality of medium-density portions and having a higher density than each of the plurality of medium-density portions. 【0006】 The absorbent article relating to this disclosure exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions. 【0007】Figure 1 is a diagram illustrating a disposable diaper 1 according to the first embodiment. Figure 2 is a diagram illustrating a disposable diaper 1 according to the first embodiment. Figure 3 is a diagram illustrating a disposable diaper 1 according to the first embodiment. Figure 4 is a diagram illustrating a disposable diaper 1 according to the first embodiment. Figure 5 is a diagram illustrating an example. Figure 6 is a diagram illustrating an example. Figure 7 is a diagram illustrating comparative manufacturing example 1. Figure 8 is a diagram illustrating comparative manufacturing example 2. Figure 9 is a diagram illustrating comparative manufacturing example 3. Figure 10 is a diagram illustrating comparative manufacturing example 4. Figure 11 is a diagram illustrating comparative manufacturing example 5. 【0008】 Specifically, the present disclosure relates to the following embodiments. [Embodiment 1] An absorbent article having longitudinal, widthwise, and thicknesswise directions that are orthogonal to each other, and having a crotch region, wherein the absorbent article comprises an absorbent core containing pulp fibers and superabsorbent polymer particles, the absorbent core comprising a low-density portion, a plurality of medium-density portions, and a high-density portion in the crotch region, the low-density portion being composed of through holes extending along the longitudinal direction, each of the plurality of medium-density portions having a base end connected to the low-density portion and an end end, extending along the widthwise direction and having a higher density than the low-density portion, and the high-density portion being in contact with each of the plurality of medium-density portions and having a higher density than each of the plurality of medium-density portions. 【0009】Absorbent articles are preferably excellent in repeated absorption of body fluids in all positions: supine, standing, and sitting. From this viewpoint, it is preferable that absorbent articles are excellent in both repeated absorption of body fluids under no pressure (hereinafter sometimes referred to as "unpressurized repeated absorption") and repeated absorption of body fluids under pressure (hereinafter sometimes referred to as "pressurized repeated absorption"). A known test for evaluating the above unpressurized repeated absorption is a test that evaluates the absorbency when the absorbent article is arranged in a U-shape (hereinafter sometimes referred to as the "U-shaped absorption test"). A known test for evaluating the above pressurized repeated absorption is a test that evaluates the absorbency when the absorbent article is arranged on a flat surface and pressure is applied (hereinafter sometimes referred to as the "pressurized absorption test"). 【0010】 For example, in the "lying down" position, the ventral region is required to have excellent pressure absorption, while the other regions are required to have excellent pressure absorption without pressure. In the "supine" position, the dorsal region is required to have excellent pressure absorption, while the other regions are required to have excellent pressure absorption without pressure. In the "lateral" position, almost the entire area is required to have excellent pressure absorption without pressure. On the other hand, in the "standing" position, almost the entire area is required to have excellent pressure absorption without pressure. In the "sitting" position, the ventral region is required to have excellent pressure absorption without pressure, while the groin and dorsal regions are required to have excellent pressure absorption without pressure. 【0011】 In the above-mentioned absorbent material, the low-density portion, which consists of through-holes extending along the longitudinal direction, allows bodily fluids to diffuse in the longitudinal direction, thus demonstrating excellent repeated absorption under pressure during pressure absorption tests. 【0012】 Furthermore, in a U-shaped absorption test, the above-mentioned absorbent material can diffuse body fluids longitudinally in the low-density area, diffuse body fluids from the low-density area to multiple medium-density areas, and then diffuse body fluids from the multiple medium-density areas to the high-density area in contact with the multiple medium-density areas, thus exhibiting excellent unpressurized repeated absorption. 【0013】Based on the above, the absorbent article exhibits excellent repeated absorption under pressure and repeated absorption without pressure, and consequently, excellent repeated absorption of body fluids in supine, standing, and sitting positions. 【0014】 Furthermore, the inventors of this application have confirmed that when each of the above-mentioned multiple medium-density sections does not have an end, for example, when a block region is formed as shown in Patent Document 1, the unpressurized repeated absorption (U-shaped absorption test) is inferior, and in particular, the repeated absorption of body fluids in an upright position is inferior. It is thought that the block region makes it difficult to transfer body fluids to other regions, for example, the non-block region shown in Patent Document 1, and after absorbing a predetermined amount of body fluid, its absorbency is poor, resulting in poor repeated absorption of body fluids. 【0015】 [Aspect 2] The absorbent article according to aspect 1, wherein the high-density portion is in contact with the ends of at least a portion of the plurality of medium-density portions. 【0016】 In the absorbent article described above, the high-density portion is in contact with at least some of the ends of the multiple medium-density portions. Therefore, in a U-shaped absorption test, the absorbent article facilitates the transfer of bodily fluids from the low-density portion to the medium-density portion, particularly from the ends to the high-density portion in the width direction, and exhibits excellent repeated absorption without pressure. As a result, the absorbent article exhibits excellent repeated absorption of bodily fluids in supine, standing, and sitting positions, particularly in standing and sitting positions. 【0017】 [Aspect 3] The absorbent article according to aspect 1 or 2, wherein the low-density portion extends along the longitudinal direction and has one low-density portion side wall located on one side in the width direction and the other low-density portion side wall located on the other side in the width direction, the base end of some of the plurality of medium-density portions is connected to the one low-density portion side wall, and the base end of another part of the plurality of medium-density portions is connected to the other low-density portion side wall. 【0018】In the absorbent article described above, the base ends of some of the multiple medium-density sections are connected to one side wall of the low-density section, and the base ends of other parts of the multiple medium-density sections are connected to the other side wall of the low-density section. Therefore, in a U-shaped absorption test, the absorbent article can repeatedly absorb body fluids in both the width direction of the low-density section and the other side, exhibiting excellent repeated absorption without pressure. As a result, the absorbent article exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions, and especially in the standing position. 【0019】 [Aspect 4] The absorbent article according to aspect 3, wherein two or more of the base ends of the plurality of medium-density sections are connected to the side wall of one low-density section, and two or more of the base ends of the plurality of medium-density sections are connected to the side wall of the other low-density section. 【0020】 In the absorbent article described above, two or more of the base ends of the multiple medium-density sections are connected to the side wall of one low-density section, and two or more of the base ends of the multiple medium-density sections are connected to the side wall of the other low-density section. Therefore, in a U-shaped absorption test, the absorbent article can repeatedly absorb body fluids in both the width direction of the low-density section and the other side, exhibiting excellent repeated absorption without pressure. As a result, the absorbent article exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions, and especially in the standing position. 【0021】 [Aspect 5] The absorbent article according to aspect 4, wherein the high-density portion is in contact with the side wall of one low-density portion and the side wall of the other low-density portion of the low-density portion, respectively, between the plurality of medium-density portions. 【0022】In the above absorbent article, since the high-density portion is in contact with each of one low-density portion side wall and the other low-density portion side wall of the low-density portion between the plurality of medium-density portions, the high-density portion is in contact with each of the plurality of medium-densities in the longitudinal direction. Therefore, in the U-shaped absorption test, the absorbent article can mainly diffuse body fluid in the longitudinal direction from the plurality of medium-density portions to the high-density portion in contact with the plurality of medium-density portions, so that it has excellent unpressurized repeated absorbency. From the above, the absorbent article has excellent repeated absorbency of body fluid in the supine, standing, and sitting positions, particularly in the standing position. 【0023】 [Aspect 6] In each of one low-density portion side wall and the other low-density portion side wall of the low-density portion, the length of the portion where the high-density portion is in contact with each of the one low-density portion side wall and the other low-density portion side wall between the plurality of medium-density portions is longer than the longitudinal length of each of the plurality of medium-density portions. The absorbent article according to Aspect 5. 【0024】 In the absorbent article, in each of one low-density portion side wall and the other low-density portion side wall of the low-density portion, the length of the portion where the high-density portion is in contact with each of the one low-density portion side wall and the other low-density portion side wall between the plurality of medium-density portions is in a predetermined relationship with the longitudinal length of each of the plurality of medium-density portions. Therefore, in the U-shaped absorption test, the absorbent article can mainly diffuse body fluid in the longitudinal direction from the plurality of medium-density portions to the high-density portion in contact with the plurality of medium-density portions, so that it has excellent unpressurized repeated absorbency. From the above, the absorbent article has excellent repeated absorbency of body fluid in the supine, standing, and sitting positions, particularly in the standing position. 【0025】 [Aspect 7] The high-density portion includes a first high-density portion disposed at a position relatively close to the low-density portion and a second high-density portion disposed at a position relatively far from the low-density portion in the width direction. The density of the superabsorbent polymer particles in the second high-density portion is higher than the density of the superabsorbent polymer particles in the first high-density portion. The absorbent article according to any one of Aspects 1 to 6. 【0026】In the absorbent article described above, the high-density portion comprises a predetermined first high-density portion and a predetermined second high-density portion. Therefore, in both the U-shaped absorption test and the pressure absorption test, the absorbent article can retain bodily fluids that have migrated from multiple medium-density portions to the first high-density portion in the second high-density portion located on the outside in the width direction of the absorbent core. This facilitates the migration of bodily fluids from the low-density portion to multiple medium-density portions, from multiple medium-density portions to the first high-density portion, and then repeatedly from the first high-density portion to the second high-density portion. Thus, the absorbent article exhibits excellent repeated absorption without pressure and repeated absorption under pressure. As a result, the absorbent article exhibits excellent repeated absorption of bodily fluids in supine, standing, and sitting positions. 【0027】 [Aspect 8] The absorbent article according to aspect 7, wherein, in a plan view of the absorbent core in the longitudinal direction, the first high-density portion overlaps with each of the plurality of medium-density portions, and the second high-density portion does not overlap with each of the plurality of medium-density portions. 【0028】 In the absorbent article described above, the first high-density portion and the second high-density portion are in a predetermined relationship with a plurality of medium-density portions. Therefore, in both the U-shaped absorption test and the pressure absorption test, when body fluid is transferred from the low-density portion to the plurality of medium-density portions, then from the plurality of medium-density portions to the first high-density portion, and then repeatedly transferred from the first high-density portion to the second high-density portion, the body fluid held by the superabsorbent polymer particles in the second high-density portion makes it difficult for the plurality of medium-density portions to be crushed, and the diffusivity in the plurality of medium-density portions is easily maintained. As a result, the absorbent article exhibits excellent repeated absorption without pressure and repeated absorption under pressure. Therefore, the absorbent article exhibits excellent repeated absorption of body fluid in supine, standing, and sitting positions. 【0029】 [Aspect 9] The absorbent article according to any one of aspects 1 to 8, wherein the length in the longitudinal direction of each of the plurality of medium-density portions is greater than 45.0% and 100.0% or less of the length in the width direction of the low-density portion. 【0030】In the absorbent article described above, the ratio of the width of the medium-density section to the width of the low-density section is within a predetermined range. Therefore, in both the U-shaped absorption test and the pressure absorption test, the absorbent article facilitates the transfer of body fluids from the low-density section to the medium-density section, and then repeatedly from the medium-density section to the high-density section. Thus, the absorbent article exhibits excellent repeated absorption without pressure (U-shaped absorption test) and repeated absorption under pressure (pressure absorption test). Based on the above, the absorbent article exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions. 【0031】 [Aspect 10] The absorbent article according to any one of aspects 1 to 9, wherein the ratio of the total length in the width direction of the low-density portion to the length in the width direction of the narrowest portion of the absorbent core is 4.0 to 45.0%. 【0032】 In the absorbent article described above, the ratio of the total width of the low-density area to the narrowest part of the absorbent core is 5 to 45%. Therefore, in the absorbent article described above, in the absorption test under pressure, the low-density area facilitates the diffusion of body fluids in the longitudinal direction through the low-density area, resulting in excellent repeated absorption under pressure. Based on the above, the absorbent article described above exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions, and especially mainly in the supine position. 【0033】 [Aspect 11] The absorbent article according to any one of aspects 1 to 10, wherein the ratio of the length of the low-density portion in the longitudinal direction to the length of the absorbent core in the longitudinal direction is 25.0 to 80.0%. 【0034】 In the absorbent article described above, the ratio of the length of the low-density section to the length of the absorbent core is within a predetermined range. Therefore, in the absorbent article described above, in the absorption test under pressure, the low-density section facilitates the diffusion of body fluids in the longitudinal direction through the low-density section, resulting in excellent repeated absorption under pressure. Based on the above, the absorbent article described above exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions, and especially in supine and sitting positions. 【0035】 [Aspect 12] The absorbent article according to any one of aspects 1 to 11, wherein the ratio of the length in the width direction of each of the plurality of medium-density portions to the length in the width direction of the low-density portion is 50.0 to 150.0%. 【0036】In the absorbent article described above, the ratio of the length of the medium-density section to the width of the low-density section is within a predetermined range. Therefore, in both the U-shaped absorption test and the pressure absorption test, the absorbent article facilitates the transfer of body fluids from the low-density section to each of the multiple medium-density sections, exhibiting excellent repeated absorption without pressure and repeated absorption under pressure. Based on the above, the absorbent article exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions. 【0037】 [Aspect 13] The absorbent article according to any one of aspects 1 to 12, wherein the low-density portion comprises a first low-density portion and a second low-density portion, and the first low-density portion and the second low-density portion are spaced apart in the width direction. 【0038】 In the absorbent article described above, the low-density portion comprises a predetermined first low-density portion and a second low-density portion. Therefore, in a pressurized absorption test, the predetermined first low-density portion and the second low-density portion of the absorbent article facilitate the longitudinal diffusion of body fluids through the low-density portion, resulting in excellent repeated absorption under pressure. Thus, the absorbent article exhibits excellent repeated absorption of body fluids, mainly in supine and sitting positions. 【0039】 [Aspect 14] The absorbent article according to any one of aspects 1 to 13, wherein the absorbent core is a single molded product. In the absorbent article described above, the absorbent core is a single molded product. Therefore, the absorbent core is thin and has excellent properties for the transfer and diffusion of bodily fluids. 【0040】 [Aspect 15] The absorbent article according to any one of aspects 1 to 14, wherein, in a plan view of the absorbent core in the thickness direction, the area of ​​the high-density portion is larger than the total area of ​​the low-density portion and the plurality of medium-density portions. 【0041】 In the absorbent article described above, the area of ​​the high-density portion is larger than the area of ​​the low-density portion and the multiple medium-density portions. Therefore, in both the U-shaped absorption test and the pressure absorption test, the absorbent article can hold a large amount of body fluid in the high-density portion, and exhibits excellent repeated absorption without pressure and repeated absorption under pressure. Based on the above, the absorbent article exhibits excellent repeated absorption of body fluid in supine, standing, and sitting positions. 【0042】The absorbent article relating to this disclosure will be described in detail below. <First Embodiment> Figures 1 to 4 are diagrams illustrating an absorbent article, specifically a disposable diaper 1, according to one embodiment of this disclosure (hereinafter sometimes referred to as "First Embodiment"). Specifically, Figure 1 is a plan view of the disposable diaper 1. Figure 2 is a plan view of the absorbent body 7 of the disposable diaper 1 (a plan view of the non-skin side 13 of the absorbent core 9). Figure 3 is a plan view of the skin side 11 of the absorbent core 9 of the disposable diaper 1. Figure 4(a) is a partially enlarged view of Figure 3. Figure 4(b) is a partially end view of the IV(b)-IV(b) end face of Figure 4(a), and for understanding purposes, the position in the width direction W is aligned with that of Figure 4(a). 【0043】 The disposable diaper 1 has a longitudinal direction L, a width direction W including the right direction RT and the left direction LF, and a thickness direction T, all of which are perpendicular to each other. The disposable diaper 1 also has a longitudinal center line LC that passes through the center of the width direction W of the disposable diaper 1 and extends in the longitudinal direction L of the disposable diaper 1. In the first embodiment, the right direction RT and the left direction LF are referred to as one and the other, respectively. 【0044】 The disposable diaper 1 is divided into a ventral region AR located on the wearer's abdominal side, a dorsal region BR located on the wearer's back side, and a groin region CR located between the ventral region AR and the dorsal region BR. The ventral region AR, the groin region CR, and the dorsal region BR are divided into three equal parts in the longitudinal direction of the disposable diaper 1. The disposable diaper 1 comprises a liquid-permeable sheet 3, a liquid-impermeable sheet 5, and an absorbent material 7 between the liquid-permeable sheet 3 and the liquid-impermeable sheet 5. 【0045】 As shown in Figure 1, the disposable diaper 1 includes a pair of leak-proof walls 101 containing an elastic member 103, a fixing part 105 for fixing the leak-proof walls 101 to the liquid-permeable sheet 3, an elastic member 107, a tape fastener 109, etc. However, these are known in the art and therefore will not be described. 【0046】The absorbent body 7 is composed of an absorbent core 9, which has the same longitudinal direction L, width direction W, and thickness direction T as the disposable diaper 1, with mutually orthogonal directions, and has a skin-facing side 11 on the liquid-permeable sheet 3 side and a non-skin-facing side 13 on the liquid-impermeable sheet 5 side, and a core wrap 15 made of tissue that covers the skin-facing side 11 and non-skin-facing side 13 of the absorbent core 9. 【0047】 The absorbent core 9 contains pulp fibers 17 and superabsorbent polymer particles 19. The absorbent core 9 is divided into three equal parts in the longitudinal direction L of the disposable diaper 1: a ventral region AR, a groin region CR, and a dorsal region BR. The absorbent core 9 has a low-density section 21, a plurality of medium-density sections 27 (specifically, 36 medium-density sections 27), and a high-density section 31, extending from the ventral region AR through the groin region CR to the dorsal region BR. The absorbent core 9 is a single molded product, and the plurality of medium-density sections 27 constitute skin-side grooves. 【0048】 The low-density section 21 is divided into a first low-density section 23 located on one side of the width direction W (right direction RT side) and a second low-density section 25 located on the other side of the width direction W (left direction LF side). Each of the first low-density section 23 and the second low-density section 25 is composed of through holes extending in the longitudinal direction L. The first low-density section 23 and the second low-density section 25 are spaced apart in the width direction W and are positioned symmetrically with respect to the longitudinal center line LC. 【0049】 The first low-density section 23 comprises two first low-density section side walls 23a extending parallel to the longitudinal direction L, specifically, one first low-density section side wall 23aa located on one side of the width direction W (right direction RT side) and the other first low-density section side wall 23ab located on the other side of the width direction W (left direction LF side). The second low-density section 25 comprises two second low-density section side walls 25a extending parallel to the longitudinal direction L, specifically, one second low-density section side wall 25aa located on one side of the width direction W (right direction RT side) and the other second low-density section side wall 25ab located on the other side of the width direction W (left direction LF side). 【0050】Each of the multiple medium-density sections 27 has a higher density than the low-density section 21 (the first low-density section 23 and the second low-density section 25). Each of the multiple medium-density sections 27 has a base end 29a, a terminal end 29b located on the opposite side of the base end 29a, and two medium-density section side walls 29c. The multiple medium-density sections 27 (36 medium-density sections 27) extend from each of the first low-density section 23 and the second low-density section 25 in a direction parallel to the width direction W, one being the rightward direction RT and the other being the leftward direction LF. Specifically, of the 36 medium-density sections 27, the base ends 29a of 9 medium-density sections 27 are connected to one side wall 23aa of the first low-density section 23, the base ends 29a of 9 medium-density sections 27 are connected to the other side wall 23ab of the first low-density section, the base ends 29a of 9 medium-density sections 27 are connected to one side wall 25aa of the second low-density section 25, and the base ends 29a of 9 medium-density sections 27 are connected to the other side wall 25ab of the second low-density section. 【0051】 In each of the first low-density section sidewall 23aa and the other first low-density section sidewall 23ab, and in each of the second low-density section sidewall 25aa and the other second low-density section sidewall 25ab, a plurality of medium-density sections 27 (specifically, nine medium-density sections 27) are arranged spaced apart in the longitudinal direction L at a predetermined pitch P. In each of the plurality of medium-density sections 27, the end 29b is in contact with the high-density section 31, and the two medium-density section sidewalls 29c extend parallel to the width direction W between the base end 29a and the end 29b, and are also in contact with the high-density section 31. 【0052】 The high-density section 31 has a higher density than each of the multiple medium-density sections 27 (specifically, 36 medium-density sections 27). The high-density section 31 surrounds the low-density section 21 (the first low-density section 23 and the second low-density section 25) and the multiple medium-density sections 27 (specifically, 36 medium-density sections 27). Specifically, the high-density section 31 is in contact with the ends 29b and two medium-density section side walls 29c of each of the multiple medium-density sections 27 (specifically, 36 medium-density sections 27). In addition, the high-density section 31 is in contact with the low-density section 21 (the first low-density section 23 and the second low-density section 25) between the multiple medium-density sections 27 (specifically, 36 medium-density sections 27). 【0053】In the disposable diaper 1 according to the first embodiment, in a pressure absorption test, the low-density portion 21 (first low-density portion 23 and second low-density portion 25) consisting of through holes extending along the longitudinal direction L can diffuse body fluids in the longitudinal direction L, thus exhibiting excellent repeated absorption of body fluids and excellent repeated absorption under pressure. 【0054】 Furthermore, in the U-shaped absorption test, the disposable diaper 1 can diffuse body fluids in the longitudinal direction L in the low-density section 21 (first low-density section 23 and second low-density section 25), and can also diffuse body fluids from the low-density section 21 to a plurality of medium-density sections 27, and then to the high-density section 31 in contact with the plurality of medium-density sections 27. Therefore, it has excellent repeated absorption of body fluids and excellent repeated absorption without pressure. 【0055】 Since the high-density section 31 is in contact with all of the ends 29b of the multiple medium-density sections 27 (specifically, 36 medium-density sections 27), in the U-shaped absorption test, the disposable diaper 1 facilitates the transfer of bodily fluids that have moved from the low-density section 21 (first low-density section 23 and second low-density section 25) to the multiple medium-density sections 27, from the side walls 29c and ends 29b of the multiple medium-density sections 27, and especially from the ends 29b to the high-density section 31 in the width direction W, resulting in excellent unpressurized repeated absorption. 【0056】 Multiple medium-density sections 27 (specifically, 36 medium-density sections 27) are configured such that 9 medium-density sections 27 are connected to one side wall 23aa of the first low-density section, 9 medium-density sections 27 are connected to the other side wall 23ab of the first low-density section, 9 medium-density sections 27 are connected to one side wall 25aa of the second low-density section, and 9 medium-density sections 27 are connected to the other side wall 25ab of the second low-density section. Therefore, in both the U-shaped absorption test and the pressure absorption test, the multiple medium-density sections 27 of the disposable diaper 1 can repeatedly absorb bodily fluids in both the width direction W of the low-density section 21 (first low-density section 23 and second low-density section 25), exhibiting excellent repeated absorption without pressure and repeated absorption under pressure. As a result, the disposable diaper 1 exhibits excellent repeated absorption of bodily fluids in supine, standing, and sitting positions. 【0057】The high-density section 31 is in contact with one side wall 23aa and the other side wall 23ab of the first low-density section 23, and with one side wall 25aa and the other side wall 25ab of the second low-density section 25, between the multiple medium-density sections 27. Therefore, in both the U-shaped absorption test and the pressure absorption test, the disposable diaper 1 facilitates the transfer of bodily fluids that have moved from the low-density section 21 (first low-density section 23 and second low-density section 25) to the multiple medium-density sections 27, mainly in the longitudinal direction L, from the multiple medium-density sections 27 to the high-density section 31, resulting in excellent repeated absorption without pressure and repeated absorption under pressure. 【0058】 The low-density section 21 comprises a first low-density section 23 and a second low-density section 25, and the first low-density section 23 and the second low-density section 25 are spaced apart in the width direction. Therefore, in the disposable diaper 1, in the pressure absorption test, the first low-density section 23 and the second low-density section 25 facilitate the diffusion of body fluids through the first low-density section 23 and the second low-density section 25 in the longitudinal direction L, resulting in excellent repeated pressure absorption. As a result, the disposable diaper 1 exhibits excellent repeated absorption of body fluids, mainly in the supine and sitting positions. 【0059】 Length L of the portion where the high-density section 31 is in contact with one of the first low-density section side walls 23aa between the multiple medium-density sections 27 (specifically, nine medium-density sections 27). EN1 The length L in the longitudinal direction of each of the multiple medium-density sections 27 is L EN2 It is longer than (the length L in the longitudinal direction of the base end 29a). The same applies to the other first low-density section side wall 23ab, the other second low-density section side wall 25aa, and the other second low-density section side wall 25ab. As a result, in both the U-shaped absorption test and the pressure absorption test, the disposable diaper 1 makes it easier to repeatedly transfer bodily fluids that have migrated from the low-density section 21 (first low-density section 23 and second low-density section 25) to the multiple medium-density sections 27, and then from the multiple medium-density sections 27 to the high-density section 31, mainly in the longitudinal direction L, thus exhibiting excellent repeated absorption without pressure and repeated absorption under pressure. 【0060】The high-density portion 31 comprises a first high-density portion 33a located relatively close to the first low-density portion 23 in the width direction W, and a second high-density portion 33b located relatively far from the first low-density portion 23, with the density of superabsorbent polymer particles 19 in the second high-density portion 33b being higher than the density of superabsorbent polymer particles 19 in the first high-density portion 33a. Furthermore, the high-density portion 31 comprises a first high-density portion 33a located relatively close to the second low-density portion 25 in the width direction W, and a second high-density portion 33b located relatively far from the second low-density portion 25, with the density of superabsorbent polymer particles 19 in the second high-density portion 33b being higher than the density of superabsorbent polymer particles 19 in the first high-density portion 33a. As a result, in both the U-shaped absorption test and the pressure absorption test, the disposable diaper 1 can retain bodily fluids that have migrated from the multiple medium-density sections 27 to the first high-density section 33a in the second high-density section 33b located on the widthwise outer side of the absorption core 9. This facilitates the migration of bodily fluids from the low-density section 21 to the multiple medium-density sections 27, from the multiple medium-density sections 27 to the first high-density section 33a, and then repeatedly from the first high-density section 33a to the second high-density section 33b, resulting in excellent repeated absorption without pressure and repeated absorption under pressure. 【0061】 In a plan view along the longitudinal direction L of the absorbent core 9, the first high-density portion 33a overlaps with each of the multiple medium-density portions 27, while the second high-density portion 33b does not overlap with each of the multiple medium-density portions 27. As a result, in the disposable diaper 1, in both the U-shaped absorption test and the pressure absorption test, when bodily fluids are transferred from the low-density portion 21 to the multiple medium-density portions 27, then from the multiple medium-density portions 27 to the first high-density portion 33a, and then repeatedly transferred from the first high-density portion 33a to the second high-density portion 33b, the multiple medium-density portions 27 are less likely to be crushed by the bodily fluids held by the superabsorbent polymer particles 19 in the second high-density portion 33b, the diffusivity in the multiple medium-density portions 27 is more easily maintained, and the diaper exhibits excellent repeated absorption without pressure and repeated absorption under pressure. 【0062】In a plan view along the thickness direction T of the absorbent core 9, the area of ​​the high-density portion 31 is larger than the total area of ​​the low-density portion 21 (first low-density portion 23 and second low-density portion 25) and the multiple medium-density portions 27. As a result, the disposable diaper 1 can hold a large amount of bodily fluids in the high-density portion 31 in both the U-shaped absorption test and the pressure absorption test, and exhibits excellent repeated absorption without pressure and repeated absorption under pressure. 【0063】 The absorbent core 9 is a single molded product. As a result, the absorbent core 9 is thin and has excellent properties for the transfer and diffusion of bodily fluids. 【0064】 The absorbent articles relating to this disclosure are not particularly limited and include, for example, disposable diapers, urine pads, incontinence pads, incontinence liners, etc. 【0065】 The absorbent article relating to this disclosure has longitudinal, widthwise, and thicknesswise directions that are perpendicular to each other. The absorbent article relating to this disclosure has a longitudinal centerline that passes through the center of the widthwise direction of the absorbent article and extends in the longitudinal direction of the absorbent article. The absorbent article relating to this disclosure may also have a widthwise centerline that passes through the center of the longitudinal direction of the absorbent article and extends in the widthwise direction of the absorbent article. In this disclosure, unless otherwise specified, the longitudinal direction and widthwise direction refer to the longitudinal direction and widthwise direction of the absorbent article, respectively. 【0066】 The absorbent article relating to this disclosure can be divided into a ventral region positioned on the wearer's abdominal side, a dorsal region positioned on the wearer's back side, and a groin region positioned between the ventral and dorsal regions. The ventral region, the groin region, and the dorsal region are divided into three equal parts in the longitudinal direction of the absorbent article. 【0067】 The absorbent article relating to this disclosure comprises an absorbent core containing pulp fibers and superabsorbent polymer particles. The absorbent article may be configured such that the absorbent core is provided as an absorbent body comprising a core wrap that covers the absorbent core from the skin side and / or non-skin side. Examples of the core wrap include those known in the art, such as tissue, nonwoven fabrics (e.g., spunbond nonwoven fabric, SMS nonwoven fabric, spunlace nonwoven fabric, etc.). 【0068】 The pulp fibers mentioned above can be any known material in the art without any particular limitations, and examples include wood pulp fibers and non-wood pulp fibers. Examples of wood pulp fibers include softwood pulp fibers and hardwood pulp fibers. Examples of non-wood pulp fibers include straw pulp fibers, bagasse pulp fibers, reed pulp fibers, kenaf pulp fibers, mulberry pulp fibers, bamboo pulp fibers, hemp pulp fibers, and cotton pulp fibers (e.g., cotton linter fibers). 【0069】 The superabsorbent polymer particles mentioned above can be any known in the art without particular limitation, such as polyacrylate-based, polysulfonate-based, maleate anhydride-based, polyacrylamide-based, polyvinyl alcohol-based, polyethylene oxide-based, polyaspartate-based, polyglutamate-based, polyalginate-based, starch-based, and cellulose-based superabsorbent polymer particles; and starch-based or cellulose-based superabsorbent polymer particles such as starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, and crosslinked sodium carboxymethylcellulose. 【0070】 The absorbent core relating to this disclosure may further include other materials known in the art, such as fibers other than pulp fibers, such as natural fibers, synthetic fibers, and semi-synthetic fibers. Examples of natural fibers include regenerated cellulose fibers. Examples of regenerated cellulose fibers include rayon fibers, such as viscose rayon, polynosic, and modal obtained from viscose, and copper ammonia rayon fibers (also called "cupro") obtained from a copper ammonia salt solution of cellulose; and lyocell and Tencel obtained by an organic solvent spinning method using an organic solvent which is a mixed solution of an organic compound and water, without going through a cellulose derivative. Examples of semi-synthetic fibers include semi-synthetic cellulose fibers, such as acetate fibers, such as triacetate fibers and diacetate fibers. 【0071】 The absorbent core contains the above-mentioned pulp fibers, preferably at a density of 50 to 600 g / m². 2 , and more preferably 100 to 350 g / m2 is included in the average area weight. Further, the above absorption core contains the above superabsorbent polymer particles, preferably at an average area weight of 50 to 400 g / m 2 , and more preferably at an average area weight of 100 to 350 g / m 2 . This is from the perspective of the present disclosure. 【0072】 In the present disclosure, the average area weights of the absorption core and the superabsorbent polymer particles are measured as follows. (1) The absorption core is taken out from the absorbent article by a method known in the art, a sample A of a predetermined size (for example, 5 cm × 5 cm) is cut out, and after drying in an atmosphere of 100°C or higher, the mass of sample A: m A (g) and the area of sample A: S A (m 2 ) are measured. (2) The average area weight of sample A: bs A (g / m 2 ) is calculated by the following formula: bs A (g / m 2 ) = m A / S A . 【0073】 (3) The same measurement is repeated 10 times in total, and the average of the average area weights: bs A (g / m 2 ) of 10 samples A is taken as the average area weight of the absorption core: BS A (g / m 2 ). (4) A sample B of a predetermined size (for example, 5 cm × 5 cm) is cut out from the absorption core, and after drying in an atmosphere of 100°C or higher, the mass of sample B: m B (g) is measured. (5) The pulp fibers and the superabsorbent polymer particles contained in sample B are separated, and the mass of the pulp fibers: m pf (g) and the m sap (g) of the superabsorbent polymer particles are measured. 【0074】 (6) The average area weight of the pulp fibers in sample B: bs pf (g / m 2 ) is calculated by the following formula: bs pf (g / m 2 ) = BS A × m pf / m BThe following is calculated: (7) Repeat the same measurement a total of 10 times and obtain the average basis weight of 10 pulp fibers: bs pf (g / m 2 ) is the average of the average basis weight of pulp fibers: BS pf (g / m 2 (8) Average basis weight of superabsorbent polymer particles in sample B: bs sap (g / m 2 ) is expressed as follows: bs sap (g / m 2 ) = BS A ×m sap / m B The following is calculated: (9) Repeat the same measurement a total of 10 times and obtain the average basis weight of 10 superabsorbent polymer particles: bs sap (g / m 2 The average of the superabsorbent polymer particles: BS sap (g / m 2 ) 【0075】 The absorbent core may have a pulp-rich layer on one or both of its skin-facing and / or non-skin-facing sides, in which the proportion of pulp fibers is higher than the average proportion of pulp fibers in the absorbent core. Having the pulp-rich layer on the skin-facing side of the absorbent core reduces the wearer's perception of the hardness of the superabsorbent polymer particles. Furthermore, having the pulp-rich layer on both the skin-facing and / or non-skin-facing sides of the absorbent core reduces the likelihood of the superabsorbent polymer particles falling off the pulp-rich layered surface of the absorbent core. 【0076】 In the absorbent article relating to this disclosure, the absorbent core comprises a low-density portion, a plurality of medium-density portions, and a high-density portion in the groin area. The low-density portion is composed of through holes extending along the longitudinal direction. Each of the plurality of medium-density portions has a base end connected to the low-density portion and an end end, extends along the width direction, and has a higher density than the low-density portion. The high-density portion is in contact with each of the plurality of medium-density portions and has a higher density than each of the plurality of medium-density portions. 【0077】In the absorbent article relating to this disclosure, the absorbent core is provided with a low-density section, a plurality of medium-density sections, and a high-density section in the groin area, thereby the absorbent article exhibits excellent repeated absorption of body fluids in both pressurized absorption tests and U-shaped absorption tests, and is excellent in both unpressurized and pressurized repeated absorption, and consequently exhibits excellent repeated absorption of body fluids in supine, standing, and sitting positions. 【0078】 In this disclosure, the density in the low-density area, the multiple medium-density areas, and the high-density area refers to the density of the absorption core. The relative densities between the low-density area, the multiple medium-density areas, and the high-density area can be determined by comparing the intensity of the transmitted light that passes through the absorption core in the thickness direction under a constant light source. That is, the lower the intensity of the transmitted light, the higher the density of the absorption core. An example of the light source is an LED backlight. By using an LED backlight as the light source, it becomes possible to distinguish the low-density area, the multiple medium-density areas, and the high-density area with high contrast under a bright and uniform light source. 【0079】 If the absorbent article relating to this disclosure comprises the absorbent core as an absorbent body including a core wrap, and the basis weight of the absorbent core is uniform, then the density can be measured as an absorbent body including the absorbent core and core wrap. 【0080】 The absorbent core may, in addition to the groin region, also include the low-density portion, the plurality of medium-density portions, and the high-density portion in the ventral and / or dorsal regions. As a result, the absorbent article becomes more efficient at repeatedly absorbing body fluids throughout the entire absorbent core in both the U-shaped absorption test and the pressure absorption test, and the absorbent article exhibits excellent repeated absorption without pressure and repeated absorption under pressure. Consequently, the absorbent article exhibits superior repeated absorption of body fluids in supine, standing, and sitting positions. 【0081】 The low-density portion is composed of through holes extending along the longitudinal direction. The low-density portion may have side walls extending along the longitudinal direction, specifically, one low-density portion side wall located on one side in the width direction and the other low-density portion side wall located on the other side in the width direction. 【0082】 In this specification, “direction along a predetermined direction” means a direction having an intersection angle of less than 45° with the predetermined direction. The direction along the predetermined direction means a direction having an intersection angle of preferably 30° or less, more preferably 20° or less, and even more preferably 5° or less with the predetermined direction. 【0083】 The low-density portion described above can consist of one or more portions. When the low-density portion consists of multiple portions, it comprises a first low-density portion and a second low-density portion, and the first and second low-density portions can be spaced apart in the width direction. By having multiple low-density portions, the absorbent article, in a pressurized absorption test, allows the predetermined first and second low-density portions to easily diffuse body fluids in the longitudinal direction through the low-density portions. 【0084】 When the above-mentioned low-density section consists of two sections, namely a first low-density section and a second low-density section, it is preferable that the first and second low-density sections are arranged symmetrically with respect to the longitudinal center line. This makes it less likely for differences in the absorbency of the absorbent article to occur between the left and right sides. 【0085】 When the above-mentioned low-density sections consist of three sections, for example, a first low-density section, a second low-density section, and a third low-density section, which are spaced apart from each other in the width direction and arranged sequentially from one side to the other in the width direction, it is preferable that the second low-density section, which is located in the middle in the width direction, is arranged along the longitudinal centerline. This makes it less likely for differences in the absorbency of the absorbent article to occur between the left and right sides. 【0086】 In each of the above-mentioned multiple medium-density sections, the base end is connected to the low-density section. Furthermore, in each of the above-mentioned multiple medium-density sections, the end is not connected to any other medium-density section. From the viewpoint of the effects of this disclosure, it is preferable that the end is not connected to any low-density section. Furthermore, from the viewpoint of the effects of this disclosure, it is preferable that each of the above-mentioned multiple medium-density sections is not connected to any other medium-density sections or low-density sections at locations other than the end. 【0087】If the low-density portion comprises one low-density portion side wall and the other low-density portion side wall, the base ends of the plurality of medium-density portions may be connected to one or both of the one low-density portion side wall and the other low-density portion side wall of the low-density portion. Preferably, the base ends of some of the plurality of medium-density portions are connected to the one low-density portion side wall, and the base ends of another portion of the plurality of medium-density portions (for example, the remainder) are connected to the other low-density portion side wall. As a result, the absorbent article can repeatedly absorb body fluids in both the width direction of the low-density portion and the other width direction in the U-shaped absorption test, and exhibits excellent unpressurized repeated absorption. 【0088】 Furthermore, the base ends of the plurality of medium-density sections can be connected in multiple ways to one or both of the side walls of the one low-density section and the other low-density section. Specifically, preferably two or more, more preferably three or more, even more preferably four or more, and even more preferably five or more base ends of the plurality of medium-density sections are connected to the side wall of the one low-density section, and preferably two or more, more preferably three or more, even more preferably four or more, and even more preferably five or more base ends of the plurality of medium-density sections are connected to the side wall of the other low-density section. Also, preferably 15 or fewer, more preferably 12 or fewer, even more preferably 11 or fewer, and even more preferably 10 or fewer base ends of the plurality of medium-density sections are connected to the side wall of the one low-density section, and preferably 15 or fewer, more preferably 12 or fewer, even more preferably 11 or fewer, and even more preferably 10 or fewer base ends of the plurality of medium-density sections are connected to the side wall of the other low-density section. As a result, the absorbent article can repeatedly absorb bodily fluids in both the width direction of the low-density portion and the other side in the U-shaped absorption test, exhibiting excellent pressure-free repeated absorption. The number of base ends of the multiple medium-density portions refers to the number of portions on one low-density side wall and the other low-density side wall of a single low-density portion. 【0089】Furthermore, the high-density portion can be in contact with at least one of the side walls of the one low-density portion and the other low-density portion between the multiple medium-density portions, and it is preferable that it is in contact with both the side wall of the one low-density portion and the other low-density portion (each of the side walls of the one low-density portion and the other low-density portion). As a result, in a U-shaped absorption test, the absorbent article facilitates the transfer of bodily fluids that have moved from the low-density portion to the multiple medium-density portions, mainly in the longitudinal direction, and the absorbent article exhibits excellent unpressurized repeated absorption. 【0090】 In at least one of the side walls of the low-density portion and the other low-density portion, the length of the portion where the high-density portion is in contact with the low-density portion side wall between the multiple medium-density portions is preferably longer than the longitudinal length of each of the multiple medium-density portions, and more preferably, in both the side wall of the low-density portion and the other low-density portion, the length of the portion where the high-density portion is in contact with the low-density portion side wall between the multiple medium-density portions is preferably longer than the longitudinal length of each of the multiple medium-density portions. As a result, in a U-shaped absorption test, the absorbent article facilitates the repeated transfer of bodily fluids that have migrated from the low-density portion to the multiple medium-density portions, mainly in the longitudinal direction, and exhibits excellent unpressurized repeated absorption. Note that "low-density portion side wall" in "the portion where the high-density portion is in contact with the low-density portion side wall between the multiple medium-density portions" refers to the applicable one of the side walls of the one low-density portion and the other low-density portion side wall. 【0091】From the above viewpoint, in at least one of the side walls of the low-density portion and the other low-density portion, the length of the portion in contact with the low-density portion side wall between the plurality of medium-density portions is preferably 1.0 times or more, more preferably 1.5 times or more, even more preferably 2.0 times or more, and even more preferably 2.5 times or more, longer than the longitudinal length of each of the plurality of medium-density portions. Also from the above viewpoint, in at least one of the side walls of the low-density portion and the other low-density portion side wall, the length of the portion in contact with the low-density portion side wall between the plurality of medium-density portions is preferably 5.0 times or less, more preferably 4.5 times or less, even more preferably 4.0 times or less, and even more preferably 3.5 times or less, longer than the longitudinal length of each of the plurality of medium-density portions. 【0092】 Preferably, the high-density portion is in contact with at least some of the ends of the plurality of medium-density portions, and more preferably, it is in contact with all of the ends of the plurality of medium-density portions. As a result, the absorbent article performs well in U-shaped absorption tests, and mainly in an upright position, it facilitates the transfer of bodily fluids that have moved from the low-density portion to the medium-density portion from the side walls and ends of the medium-density portion, and especially from the ends to the high-density portion in the width direction, and it has excellent unpressurized repeated absorption. 【0093】The high-density portion may comprise a first high-density portion located relatively close to the low-density portion in the width direction, and a second high-density portion located relatively far from the low-density portion. In this case, it is preferable that the density of the superabsorbent polymer particles in the second high-density portion is higher than the density of the superabsorbent polymer particles in the first high-density portion. As a result, in both the U-shaped absorption test and the pressure absorption test, the absorbent article can retain bodily fluids that have migrated from the multiple medium-density portions to the first high-density portion in the second high-density portion located on the outside of the width direction of the absorbent core. This facilitates the migration of bodily fluids from the low-density portion to the multiple medium-density portions, from the multiple medium-density portions to the first high-density portion, and then repeatedly from the first high-density portion to the second high-density portion, thus the absorbent article exhibits excellent repeated absorption without pressure and repeated absorption under pressure. 【0094】 When the high-density portion comprises a first high-density portion and a second high-density portion, it is preferable that, in a plan view of the absorbent core in the longitudinal direction, the first high-density portion overlaps with each of the multiple medium-density portions, while the second high-density portion does not overlap with each of the multiple medium-density portions. As a result, in both the U-shaped absorption test and the pressure absorption test, when the absorbent article transfers bodily fluids from the low-density portion to the multiple medium-density portions, then from the multiple medium-density portions to the first high-density portion, and then repeatedly transfers them from the first high-density portion to the second high-density portion, the multiple medium-density portions are less likely to be crushed by the bodily fluids held by the superabsorbent polymer particles in the second high-density portion, the diffusivity in the multiple medium-density portions is more easily maintained, and the absorbent article exhibits excellent repeated absorption without pressure and repeated absorption under pressure. The first high-density portion and the second high-density portion can be formed, for example, by carrying out the method for manufacturing an absorbent core described later, specifically by manufacturing an integrally molded product using the method for manufacturing an absorbent core described later. 【0095】In this specification, the density of superabsorbent polymer particles can be determined using X-rays as follows: (1) Preparation of absorbent sample for X-ray fluoroscopic imaging A sample containing the absorbent core to be measured is prepared from an absorbent article. This sample is the absorbent core from which the elastic member, liquid permeable sheet, liquid impermeable sheet, etc. of the absorbent article have been removed. If the absorbent core is an absorbent comprising an absorbent core and a core wrap, the absorbent itself can be used as the sample. Furthermore, if the absorbent article has an absorbent core (or absorbent body) and a liquid permeable sheet, liquid impermeable sheet, etc. integrally formed, and it is difficult to remove the liquid permeable sheet and / or liquid impermeable sheet, etc. without destroying the shape of the absorbent core (or absorbent body), the sample may include the absorbent core (or absorbent body) from which the elastic member has been removed, and the liquid permeable sheet and / or liquid impermeable sheet. 【0096】 (2) Acquisition of X-ray fluoroscopic images of the sample in plan view Using the following X-ray imaging apparatus, with a field of view size of 30 × 20 mm, X-ray fluoroscopic images showing the distribution of the superabsorbent polymer over its thickness are acquired in BMP format by sequentially transmitting images in the thickness direction from one corner of the sample, across the entire length and width directions. Next, the X-ray fluoroscopic images are tiled in the length and width directions to represent the entire absorber, and a composite image in BMP format representing the entire absorber is obtained. - X-ray imaging apparatus: Beamsense Co., Ltd., FLEX-M863 - Imaging conditions: Tube voltage 35 kV, tube current 100 μA, pixel size: 20 × 20 μm - Number of pixels: 1500 × 1000 pixels, resolution: 2 μm (geometric magnification 10x) - Image stitching software / image measurement software: Unique Co., Ltd., UN Analyzer 【0097】 (3) Method for determining the density of superabsorbent polymer particles in a sample Using the image processing software described above, the composite image in BMP format obtained in (2) above is adjusted to a predetermined threshold to determine the density of the superabsorbent polymer particles. The predetermined threshold is such that the low-density part of the absorber does not contain pixels, and the boundary between the low-density part and the medium-density part and / or high-density part can be determined as the contour of the pixels. 【0098】 In the absorbent article relating to this disclosure, the ratio of the length (width) in the longitudinal direction of each of the multiple medium-density sections to the length (width) in the width direction of the low-density section (hereinafter sometimes referred to as the "ratio of medium-density section width to low-density section width") is preferably greater than 45.0%, more preferably 55.0% or more, and even more preferably 60.0% or more. Furthermore, the ratio of medium-density section width to low-density section width is preferably 100.0% or less, more preferably 90.0% or less, and even more preferably 85.0% or less. As a result, in both the U-shaped absorption test and the pressure absorption test, the absorbent article facilitates the transfer of bodily fluids from the low-density section to the medium-density section, and then repeatedly from the medium-density section to the high-density section, and the absorbent article exhibits excellent repeated absorption without pressure and repeated absorption under pressure. 【0099】 In the absorbent article relating to this disclosure, the ratio of the total length (width) of the low-density portion in the width direction to the length (width) of the narrowest portion of the absorbent core (hereinafter sometimes referred to as the "ratio of total width of the low-density portion to the narrowest portion of the absorbent core") is preferably 4.0% or more, more preferably 6.0% or more, and even more preferably 7.0% or more. Furthermore, the ratio of total width of the low-density portion to the narrowest portion of the absorbent core is preferably 45.0% or less, more preferably 35.0% or less, and even more preferably 30.0% or less. As a result, in the absorbent article, in a pressurized absorption test, the low-density portion facilitates the diffusion of body fluids in the longitudinal direction through the low-density portion, resulting in excellent repeated pressurized absorption. 【0100】 In the absorbent article relating to this disclosure, the ratio of the length of the low-density portion in the longitudinal direction to the length of the absorbent core in the longitudinal direction (hereinafter sometimes referred to as the "ratio of low-density portion length to absorbent core length") is preferably 25.0% or more, more preferably 35.0% or more, and even more preferably 45.0% or more. Furthermore, the ratio of low-density portion length to absorbent core length is preferably 80.0% or less, more preferably 75.0% or less, and even more preferably 70.0% or less. As a result, in the absorbent article, in the absorption test under pressure, the low-density portion facilitates the diffusion of body fluids in the longitudinal direction through the low-density portion, and the absorbent article exhibits excellent repeated absorption without pressure. 【0101】 In the absorbent article relating to this disclosure, the ratio of the length in the width direction of each of the multiple medium-density sections to the length (width) in the width direction of the low-density section (hereinafter sometimes referred to as the "ratio of length of medium-density section to width of low-density section") is preferably 50.0% or more, more preferably 60.0% or more, and even more preferably 65.0% or more. Furthermore, the ratio of length of medium-density section to width of low-density section is preferably 150.0% or less, more preferably 120.0% or less, and even more preferably 100.0% or less. As a result, the absorbent article facilitates the transfer of bodily fluids from the low-density section to each of the multiple medium-density sections in both the U-shaped absorption test and the pressure absorption test, and the absorbent article exhibits excellent repeated absorption without pressure and repeated absorption under pressure. 【0102】 In the absorbent article relating to this disclosure, it is preferable that the area of ​​the high-density portion is larger than the total area of ​​the low-density portion and the plurality of medium-density portions in a plan view in the thickness direction of the absorbent core. As a result, the absorbent article can hold a large amount of bodily fluid in the high-density portion in both the U-shaped absorption test and the pressure absorption test, and exhibits excellent repeated absorption without pressure and repeated absorption under pressure. 【0103】The absorbent core according to this disclosure can be manufactured by referring to Japanese Patent Application Publication No. 2019-118722, etc. Specifically, the mold member is provided with high protrusions corresponding to low-density areas (hereinafter referred to as "high protrusions corresponding to low-density areas"), low protrusions corresponding to multiple medium-densities (hereinafter referred to as "low protrusions corresponding to medium-density areas"), and non-protrusions corresponding to high-density areas (hereinafter referred to as "non-protrusions corresponding to high-density areas"). Pulp fibers and superabsorbent polymer particles are not laminated on the high protrusions corresponding to low-density areas, a certain amount of pulp fibers and superabsorbent polymer particles are laminated on the low protrusions corresponding to medium-density areas, and a larger amount of pulp fibers and superabsorbent polymer particles than that on the low protrusions corresponding to medium-density areas is laminated on the non-protrusions corresponding to high-density areas to form a laminate. The laminate has a base portion derived from the non-protrusions corresponding to high-density areas, a groove portion derived from the low protrusions corresponding to medium-density areas, and a through hole derived from the high protrusions corresponding to low-density areas. Next, if desired, the laminate is sandwiched between core wraps such as tissue paper, and the laminate sandwiched between the core wraps is passed between a pair of press rolls of a press device to form an absorbent core (absorbent body) which is an integrally molded product having a low-density section, multiple medium-density sections, and a high-density section. 【0104】 The laminated material has a base portion derived from a non-protruding portion corresponding to a high-density area, a groove portion derived from a low-protrusion portion corresponding to a medium-density area, and a through-hole derived from a high-protrusion portion corresponding to a low-density area. However, when the laminated material is passed between a pair of press rolls of a press device, the base portion derived from the non-protruding portion corresponding to the high-density area and the groove portion derived from the low-protrusion portion corresponding to the medium-density area become approximately the same height, meaning that the groove portion derived from the low-protrusion portion corresponding to the medium-density area may disappear. In that case, both the skin side and the non-skin side of the integrally molded absorbent core become approximately flat in appearance. 【0105】 Even in such cases, an absorbent core used such that the grooves derived from the low protrusions corresponding to the medium-density areas face the skin side may be referred to for convenience as an "absorbent core with skin-side grooves," and the multiple medium-density areas may be referred to as "skin-side grooves." Similarly, an absorbent core used such that the grooves derived from the low protrusions corresponding to the medium-density areas face the non-skin side may be referred to for convenience as an "absorbent core with non-skin-side grooves," and the multiple medium-density areas may be referred to as "non-skin-side grooves." 【0106】The present disclosure will be explained below with reference to examples, but the present disclosure is not limited to these examples. [Manufacturing Example 1] Absorbent core No. 1 shown in Figure 3 was manufactured according to the method described herein, with reference to Japanese Patent Application Publication No. 2019-118722, but the press processing was performed in batch processing using a gantry-type hydraulic press. The superabsorbent polymer particles (SAP) used were sodium polyacrylate-based, and the pulp fibers used were softwood pulp fibers. A laminate sandwiched between tissues was placed between a pair of upper and lower plates of a gantry-type hydraulic press, and the press pressure and press time were adjusted to obtain absorbent core No. 1 with a thickness of 2.7 mm. Next, absorbent core No. 1 was used to have skin-side grooves to manufacture disposable diaper No. 1 shown in Figure 1. 【0107】 Table 1 shows the characteristic values ​​of absorption core No. 1. The thickness of absorption core No. 1 was measured using a Peacock dial gauge manufactured by Ozaki Seisakusho Co., Ltd., with the intersection of the longitudinal centerline of absorption core No. 1 and the widthwise centerline extending parallel to the width direction through the longitudinal centerline as the center. 【0108】 [Manufacturing Examples 2 and 4-6] Absorbent cores No. 2 and No. 4-6 shown in Figure 5 were manufactured in the same manner as in Manufacturing Example 1. Furthermore, disposable diapers No. 2 and No. 4-6 shown in Figure 1 were manufactured by using absorbent cores No. 2 and No. 4-6 so as to have skin-side grooves. Note that absorbent cores No. 2 and No. 4-6 have different widths in the width direction of the low-density section 21 and different longitudinal lengths (widths) (mm) of the multiple medium-density sections 27. 【0109】 [Manufacturing Example 3] Absorbent core No. 3, shown in Figure 6, was manufactured in the same manner as in Manufacturing Example 1. Furthermore, disposable diaper No. 3, shown in Figure 1, was manufactured by using absorbent core No. 3 with non-skin grooves. Note that absorbent core No. 2 and No. 3 differ in whether they have skin grooves or non-skin grooves. 【0110】[Comparative Manufacturing Example 1] Absorbent core No. 7, shown in Figure 7, was manufactured in the same manner as in Manufacturing Example 1. Disposable diaper No. 7, shown in Figure 1, was also manufactured using absorbent core No. 7. Absorbent core No. 7 differs from absorbent core No. 1 mainly in that it does not have multiple medium-density sections. 【0111】 [Comparative Manufacturing Example 2] Absorbent core No. 8, shown in Figure 8, was manufactured in the same manner as in Manufacturing Example 1. Disposable diaper No. 8, shown in Figure 1, was also manufactured using absorbent core No. 8. Absorbent core No. 8 differs from absorbent cores No. 2 and No. 3 in that it does not have multiple medium-density sections. 【0112】 [Comparative Manufacturing Example 3] Absorbent core No. 9 shown in Figure 9 was manufactured in the same manner as in Manufacturing Example 1. Disposable diaper No. 9 shown in Figure 1 was also manufactured using absorbent core No. 9. Absorbent core No. 9 differs from absorbent cores No. 2 and No. 3 in that each of the multiple medium-density sections 27 is a through-hole. 【0113】 [Comparative Manufacturing Example 4] Absorbent core No. 10 shown in Figure 10 was manufactured in the same manner as in Manufacturing Example 1. Furthermore, disposable diaper No. 10 shown in Figure 1 was manufactured by using absorbent core No. 10 so that it has skin-side grooves. Absorbent core No. 10 is modeled after the second absorbent core 220 shown in Patent Document 1, and differs mainly from absorbent cores No. 2 and No. 5 in that the multiple medium-density sections 27 do not have ends. 【0114】 [Comparative Manufacturing Example 5] Absorbent core No. 11 shown in Figure 11 was manufactured in the same manner as in Manufacturing Example 1. Disposable diaper No. 11 shown in Figure 1 was also manufactured using absorbent core No. 11. Absorbent core No. 11 differs from absorbent core No. 1 and absorbent core No. 2, etc., in that it does not have a low-density area and multiple medium-density areas. 【0115】 [Examples 1-6 and Comparative Examples 1-5] Disposable diapers No. 1-11 were subjected to a U-shaped absorption test and a pressure absorption test. The results are shown in Table 1. The procedures for the U-shaped absorption test and the pressure absorption test are as follows. 【0116】[U-shaped absorption test] (1) Mark A and Mark B are placed on the liquid permeable sheet of the disposable diaper. Mark A is the point where the longitudinal center line and the width center line of the disposable diaper intersect, and Mark B is 70 mm ventrally from Mark A. (2) The disposable diaper is placed with the liquid permeable sheet facing inward in a U-shaped device that has a roughly U-shape when viewed from the side. The disposable diaper is placed in the U-shaped device so that Mark A is aligned with the center of the U-shaped device (the lowest point). 【0117】 <Cycle 1> (3) Inject 80 mL of artificial urine (first injection) from the burette towards Mark B at a rate of 80 mL / 10 seconds. (4) Record the time from the start of the first injection of artificial urine until the artificial urine on the permeable sheet is gone as the absorption time (80 mL). 【0118】 <Cycle 2> (5) Ten minutes after the start of the first infusion of artificial urine, infuse 80 mL of artificial urine (second infusion) from the burette towards Mark B at a rate of 80 mL / 10 seconds. (6) Record the time from the start of the second infusion of artificial urine until the artificial urine on the permeable sheet is gone as the absorption time (160 mL). 【0119】 <Third Cycle> (7) Ten minutes after the start of the second infusion of artificial urine, infuse 80 mL of artificial urine (third infusion) from the burette towards Mark B at a rate of 80 mL / 10 seconds. (8) Record the time from the start of the third infusion of artificial urine until the artificial urine on the permeable sheet is gone as the absorption time (240 mL). 【0120】 Artificial urine is prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride, and approximately 1 g of the dye Blue No. 1 in 10 L of deionized water. 【0121】 [Pressure Absorption Test] (1) Mark A is placed on the liquid permeable sheet of the disposable diaper. Mark A is the point where the longitudinal center line and the widthwise center line of the disposable diaper intersect. (2) Area with a hole with a diameter of 30 mm in the center: 364 cm² 2A pressurized dripping jig is prepared in which a cylinder with an inner diameter of 30 mm and a length of 230 mm is joined to a hole in an acrylic plate. When liquid is introduced into the cylinder of the pressurized dripping jig, the liquid can be dripped onto a disposable diaper placed below the jig. 【0122】 (3) Place the pressurized drip jig on top of the disposable diaper so that mark A and the hole in the pressurized drip jig are aligned, and place two 3.5 kg weights on top of the pressurized drip jig, 100 mm apart in the longitudinal direction of the disposable diaper with the hole as the center. (4) Set the burette containing the artificial urine so that its tip is inserted 10 mm into the cylinder of the pressurized drip jig. (5) Inject 40 mL of artificial urine (40 mL) from the burette into the cylinder at a rate of 40 mL / 5 seconds. 【0123】 <Cycle 1> (6) Record the time from the start of the first infusion of artificial urine until the artificial urine on the permeable sheet is gone as the absorption time (40 mL). <Cycle 2> (7) Five minutes after the start of the first infusion of artificial urine, inject 40 mL of artificial urine (second infusion) into the cylinder from the burette at a rate of 40 mL / 5 seconds. (8) Record the time from the start of the second infusion of artificial urine until the artificial urine on the permeable sheet is gone as the absorption time (80 mL). 【0124】 <Cycles 3 to 6> (9) Cycles 3 to 6 are performed by repeating Cycle 2 four times. After completing the infusion of artificial urine in Cycle 6, the time from the start of the 6th infusion of artificial urine until the artificial urine on the permeable sheet is gone is recorded as the absorption time (240 mL). The artificial urine is prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride, and approximately 1 g of the dye Blue No. 1 in 10 L of deionized water. 【0125】 【0126】Disposable diapers No. 1 to No. 6 are found to be superior in absorption time (240 mL) in the U-shaped absorption test and the pressure absorption test compared to disposable diapers No. 7 to No. 11. In particular, disposable diapers No. 2 and No. 3 are found to be superior in absorption time (240 mL) in the U-shaped absorption test and the pressure absorption test compared to disposable diaper No. 8, which does not have multiple medium-density sections; disposable diaper No. 9, which has multiple medium-density sections that are through holes; and disposable diaper No. 10, which has multiple medium-density sections that do not have ends. 【0127】 Furthermore, disposable diaper No. 4 has a width of 6 mm in the low-density section and a length of 4 mm in the longitudinal section of multiple medium-density sections, resulting in a longer absorption time (240 mL) in the pressure absorption test. However, if, for example, disposable diapers No. 9 and No. 10 have a width of 6 mm in the low-density section and a length of 4 mm in the longitudinal section of multiple medium-density sections, it is expected that they will perform worse than disposable diaper No. 4, especially in the pressure absorption test. 【0128】 1 Disposable diaper 3 Permeable sheet 5 Impermeable sheet 7 Absorbent material 9 Absorbent core 11 Skin side 13 Non-skin side 15 Core wrap 17 Pulp fiber 19 Superabsorbent polymer particles 21 Low density area 23 First low density area 23a Side wall of the first low density area 25 Second low density area 25a Side wall of the second low density area 27 Medium density area 29a Base end 29b End 29c Side wall of the medium density area 31 High density area 33a First high density area 33b Second high density area L Longitudinal direction W Width direction T Thickness direction AR Ventral region CR Groin region BR Dorsal region

Claims

1. An absorbent article having longitudinal, widthwise, and thicknesswise directions that are orthogonal to each other, and having a crotch region, wherein the absorbent article comprises an absorbent core containing pulp fibers and superabsorbent polymer particles, the absorbent core comprising a low-density portion, a plurality of medium-density portions, and a high-density portion in the crotch region, the low-density portion being composed of through holes extending along the longitudinal direction, each of the plurality of medium-density portions having a base end connected to the low-density portion and an end end, extending along the widthwise direction and having a higher density than the low-density portion, and the high-density portion being in contact with each of the plurality of medium-density portions and having a higher density than each of the plurality of medium-density portions.

2. The absorbent article according to claim 1, wherein the high-density portion is in contact with the ends of at least some of the plurality of medium-density portions.

3. The absorbent article according to claim 1 or 2, wherein the low-density portion extends along the longitudinal direction and has one low-density portion side wall located in one of the width directions and the other low-density portion side wall located in the other width direction, the base end of some of the plurality of medium-density portions is connected to the one low-density portion side wall, and the base end of another portion of the plurality of medium-density portions is connected to the other low-density portion side wall.

4. The absorbent article according to claim 3, wherein two or more of the base ends of the plurality of medium-density portions are connected to the side wall of one low-density portion, and two or more of the base ends of the plurality of medium-density portions are connected to the side wall of the other low-density portion.

5. The absorbent article according to claim 4, wherein the high-density portion is in contact with the side wall of one low-density portion and the side wall of the other low-density portion of the low-density portion between the plurality of medium-density portions.

6. The absorbent article according to claim 5, wherein in each of the side walls of the low-density portion and the other low-density portion, the length of the portion in which the high-density portion is in contact with each of the side walls of the low-density portion and the other low-density portion between the plurality of medium-density portions is longer than the length of each of the plurality of medium-density portions in the longitudinal direction.

7. The absorbent article according to any one of claims 1 to 6, wherein the high-density portion comprises a first high-density portion located relatively close to the low-density portion in the width direction, and a second high-density portion located relatively far from the low-density portion, and the density of the superabsorbent polymer particles in the second high-density portion is higher than the density of the superabsorbent polymer particles in the first high-density portion.

8. The absorbent article according to claim 7, wherein, in a plan view of the absorbent core in the longitudinal direction, the first high-density portion overlaps with each of the plurality of medium-density portions, and the second high-density portion does not overlap with each of the plurality of medium-density portions.

9. The absorbent article according to any one of claims 1 to 8, wherein the ratio of the length in the longitudinal direction of each of the plurality of medium-density portions to the length in the width direction of the low-density portion is greater than 45.0% and 100.0% or less.

10. The absorbent article according to any one of claims 1 to 9, wherein the ratio of the total length in the width direction of the low-density portion to the length in the width direction of the narrowest portion of the absorbent core is 4.0 to 45.0%.

11. The absorbent article according to any one of claims 1 to 10, wherein the ratio of the length of the low-density portion in the longitudinal direction to the length of the absorbent core in the longitudinal direction is 25.0 to 80.0%.

12. The absorbent article according to any one of claims 1 to 11, wherein the ratio of the length in the width direction of each of the plurality of medium-density portions to the length in the width direction of the low-density portion is 50.0 to 150.0%.

13. The absorbent article according to any one of claims 1 to 12, wherein the low-density portion comprises a first low-density portion and a second low-density portion, and the first low-density portion and the second low-density portion are spaced apart in the width direction.

14. The absorbent article according to any one of claims 1 to 13, wherein the absorbent core is a single molded product.

15. The absorbent article according to any one of claims 1 to 14, wherein, in a plan view of the absorbent core in the thickness direction, the area of ​​the high-density portion is larger than the total area of ​​the low-density portion and the plurality of medium-density portions.

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