JP6667495B2 - Absorbent articles - Google Patents

Description

  The present invention relates to an absorbent article.

  Absorbent articles that absorb high-viscosity liquid excrement are known. For example, Patent Literature 1 includes a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber located between the top sheet and the back sheet, wherein the absorber has an absorbent core, And a porous particle layer located on the surface sheet side of the absorbent core. Examples of the porous particles of the porous particle layer include fiber balls and porous cellulose particles. According to Patent Literature 1, the high-viscosity liquid excreta excreted on the topsheet of the absorbent article diffuses through the porous particle layer and is temporarily stored in the porous particle layer. At this time, the voids between the porous particles and the voids in the porous particles function as a flow path for the liquid excrement. As a result, the liquid excrement quickly diffuses through the porous particle layer and efficiently transfers to the absorber. However, among the components of the liquid excrement, water easily migrates from the porous particle layer to the absorber, but solid components such as fibers are easily captured and retained by the porous particle layer. As a result, the movement of the liquid excrement (mainly a solid component) remaining in the porous particle layer as a fluid becomes slow. Thereby, when pressure is applied to the absorbent article, exudation (rewet) of liquid excrement from the porous particle layer to the liquid-permeable topsheet is suppressed.

JP 2015-188709 A

  Patent Literature 1 describes a case in which high-viscosity liquid excrement has a property of being easily separated into a solid component and a liquid component. However, in some cases, high-viscosity liquid excrement has properties that are difficult to separate into a solid component and a liquid component. When high-viscosity liquid excrement (hereinafter also referred to as “high-viscosity excretion”) having properties that are difficult to separate into a solid component and a liquid component is excreted on the top sheet of the absorbent article, Not only the solid component but also the liquid component can be captured and held in the voids between the porous particles or the voids in the porous particles. When pressure is applied to the absorbent article holding such a high-viscosity excretory liquid from the outside, the porous particles are compressed, the volume of the voids in the porous particles is reduced, and the high-viscosity excretory liquid in the voids is reduced. May leak out of the porous particle layer. In addition, since there is nothing in the gaps between the porous particles that hinders movement, the highly viscous excreted liquid in the gaps may leak out of the porous particle layer. In this case, the leaked high-viscosity liquid exudes to the topsheet and causes rewet.

  Therefore, an object of the present invention is to provide an absorbent article capable of suppressing or exuding (rewetting) of a high-viscosity excretory liquid to a topsheet while maintaining or improving the absorption performance of the high-viscosity excretory liquid. It is in.

The absorbent article of the present invention is (1) an absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber located between the top sheet and the back sheet. There, the absorbent body, an absorbent core, located on the surface of the absorbent core on the top sheet side, comprising a lump fiber layer containing a plurality of lump fibers, each of the plurality of lump fibers , Formed of massive fibers, having a high fiber density, a hardly crushable core portion, and a protruding fiber portion formed of crimpable fibers protruding outward from the periphery of the core portion and having a low fiber density and easily crushable, And the adjacent mass fibers are in contact with each other via the protruding fiber portion, and a specific volume of the mass fiber layer when a pressure of 3 g / cm ² is applied to the mass fiber layer is defined as a reference specific volume. , 3 g / cm ² greater pressure is applied to the bulk fiber layer The specific volume of the bulk fiber layer at that time is defined as the load specific volume, the ratio of the load specific volume to the reference specific volume is defined as the specific volume ratio, and the ratio of the change in the specific volume ratio to the change in the pressure applied to the bulk fiber layer Is the rate of change, and the first rate of change, which is the rate of change when the change in pressure applied to the massive fiber layer is 3 g / cm ² to 5 g / cm ² , is −0.12 (g / cm ² ) ⁻ The second rate of change, which is not less than ^{1 and not} more than -0.025 (g / cm ² ) ⁻¹ , and is the rate of change when the change in pressure applied to the massive fiber layer is 25 g / cm ² to 30 g / cm ^2. Is -0.02 (g / cm ² ) ^-1 or more and less than 0 (g / cm ² ) ^-1 .

In the present absorbent article, in the massive fiber layer, adjacent massive fibers are in contact with each other via the protruding fiber portions, and the fibers of the protruding fiber portions are entangled while repelling each other, so that the protruding fibers are formed between the adjacent core portions. The voids (voids between the core portions) are formed by the fibers of the portions. At this time, since the fibers of the protruding fiber portion are composed of crimpable fibers and have a relatively low fiber density, when a pressure (load) is applied to the massive fiber layer, the fibers can easily contract according to the pressure. . Therefore, since the protruding fiber portion contracts and absorbs the pressure, the influence of the pressure on the core portion can be made less likely, and the deformation of the core portion can be suppressed. Here, when pressure is applied to the massive fiber layer, the specific volume of the massive fiber layer decreases. However, as a mode of the decrease, first, when the pressure is small, the specific volume is reduced by mainly shrinking the protruding fiber portion having many voids and easily shrinking. When the pressure is large, after the contraction of the protruding fiber portion has sufficiently proceeded, the specific volume is further reduced by mainly contracting the core portion, which has few voids and is difficult to contract. Therefore, when the specific volume of the massive fiber layer is reduced, the contraction of the protruding fiber portion and the contraction of the core portion progress stepwise. In the absorbent article, the first rate of change when the change in pressure applied to the massive fiber layer is 3 g / cm ² to 5 g / cm ² is −0.12 (g / cm ² ) ⁻¹ or more, and −0.025. ^{(g /} cm ²⁾ is less than ^-1, the second rate of change when the change in pressure applied to the bulk fiber layer from 25 g / cm ² of 30 g / cm ² is -0.02 ^{(g /} cm ^{2) -1} As described above, it is less than 0 (g / cm ² ) ⁻¹ . However, a state in which a pressure of 3 g / cm ² is applied to the massive fiber layer simulates a state in which almost no pressure is applied to the absorbent article in which the wearer is standing, and a pressure of 25 g / cm ² is applied to the massive fiber layer. The state in which is applied simulates a state in which a large pressure is applied to the absorbent article in which the wearer is sitting. Then, 3 g / pressure (load) changes from cm ² 5g / cm ² corresponds to the shrinkage variation of the projecting fiber portion, shrinkage variation change of the core portion of 25 g / cm ² from 30 g / cm ² pressure (load) Corresponding to
When such an absorbent article absorbs a high-viscosity liquid excrement having properties that are difficult to separate into a solid component and a liquid component, that is, when absorbing a high-viscosity excretion, voids in the core portion of the massive fiber in the massive fiber layer and High-viscosity excreted liquid can be captured and retained in the voids in the protruding fiber portion. At this time, since the core portion having the highest fiber density in the massive fiber layer has a high fiber density, when there is room for capacity, the high-viscosity excreted liquid once held in the protruding fiber portion is removed from the portion adjacent to the protruding fiber portion. Can be absorbed from and retained. Then, when pressure is applied to such an absorbent article due to a change in the posture of the wearer in a state of holding the high-viscosity excrement, the crimping fibers of the protruding fiber portion are applied in accordance with the pressure. By contracting and becoming a cushion, the pressure can be absorbed. Therefore, the pressure can be hardly applied to the core portion. Thereby, it is possible to make it difficult for the high-viscosity excreted liquid held in the gap in the core portion to be pushed out. Furthermore, leakage from the core portion can be suppressed by reducing the distance between the bulk fibers and increasing the fiber density of the voids in the protruding fiber portion, that is, by increasing the fiber density around the core portion. Here, when a large amount of high-viscosity excretion liquid is held in the voids of the protruding fiber portion, the high-viscosity excretion liquid held in the voids of the protruding fiber portion is contracted by the contraction of the protruding fiber portion. It can be considered that it is easily extruded. However, since the high-viscosity excretion liquid has moved below the protruding fiber portion (absorber side) by its own weight, it is covered with the protruding fiber portion above (top sheet side), that is, upward. It is in a state with a lid. As a result, even if the gap of the protruding fiber portion shrinks, the high-viscosity excreted liquid can be prevented from leaking to the top sheet side by the upper protruding fiber portion (lid). In addition, the high-viscosity excreted liquid that has nowhere to go is inserted into the voids of the bulk fibers and the protruding fiber portions of the portion where no load is applied (for example, the crevices of the buttocks) via the protruding fiber portions of the bulk fibers in the middle. You can move. Thereby, it is hard to be pushed out. With such an absorbent article, it is possible to further suppress the exudation of liquid excrement to the topsheet while maintaining or improving the absorption performance for high-viscosity excretion liquid. In the case of liquid excrement that has a property of being easily separated into a solid component and a liquid component, the solid component can be mainly absorbed by the massive fiber layer, and the liquid component can be mainly absorbed by the absorbent core.

However, when the first rate of change is less than −0.12 (g / cm ² ) ⁻¹ , that is, when the absolute value exceeds 0.12, the specific volume ratio due to the contraction of the protruding fiber portion with respect to the change in pressure applied to the massive fiber layer. Is too large (the voids in the protruding fiber portion are large, or the fiber amount in the protruding fiber portion is small, etc.), and the retained high-viscosity excreted liquid is easily released. On the other hand, when the first rate of change exceeds -0.025 (g / cm ² ) ⁻¹ , that is, when the absolute value is less than 0.025, the specific volume due to the contraction of the protruding fiber portion with respect to the change in the pressure applied to the massive fiber layer Since the decrease in the ratio is too small (the voids in the protruding fiber portion are small, or the amount of fiber in the protruding fiber portion is large, etc.), it becomes difficult to sufficiently retain the high-viscosity excreted liquid. When the second rate of change is less than −0.02 (g / cm ² ) ⁻¹ , that is, when the absolute value exceeds 0.015, the specific volume ratio of the core portion shrinks with respect to the change in pressure applied to the massive fiber layer. Since the decrease is too large (such as a large void in the core portion or a small fiber amount in the core portion), the core portion is easily deformed, and the high-viscosity excreted liquid is easily permeated.

In the absorbent article of the present invention, (2) the average thickness of the protruding fiber portion on the surface of the core portion in the bulk fiber is 0.4 times or more and 2 times or less the average diameter of the core portion. And the absorbent article according to (1).
In the present absorbent article, the average thickness of the protruding fiber portion is 0.4 times or more and 2 times or less the average diameter of the core portion. When the average thickness of the protruding fiber portion is in this range, the high-viscosity excreted liquid can be appropriately held in the space of the protruding fiber portion, and when the pressure is applied to the massive fiber layer, the space of the protruding fiber portion is reduced. The cushion can be appropriately shrunk into a cushion, and the pressure can be appropriately absorbed, so that the pressure can be less applied to the core portion. At this time, if the average thickness of the protruding fiber portion is less than 0.4 times the average diameter of the core portion, the void of the protruding fiber portion cannot be sufficiently ensured, and the core portion is easily applied with pressure, and from the core portion. High-viscosity excretion liquid is easy to exude. When the average thickness of the protruding fiber portion is more than twice the average diameter of the core portion, the protruding fiber portion shrinks while a large amount of high-viscosity excreted liquid is held in the protruding fiber portion, and the protruding fiber portion High-viscosity excreted liquid is easy to seep out from the part.

The absorbent article according to the present invention is (3) the absorbent article according to (1) or (2), wherein the fibers of the core portion and the fibers of the protruding fiber portion in the bulk fiber are the same. You may.
In the present absorbent article, the fibers of the core portion and the fibers of the protruding fiber portion are the same. For this reason, since the fibers are continuously connected from the core portion to the protruding fiber portion, the high-viscosity excreted liquid can be supplemented by the protruding fiber portion and guided to the core portion more easily. At the same time, the predetermined protruding fiber portion and the core portion can be formed more accurately, so that the core portion having a high fiber density can be hardly crushed, and the protruding fiber portion having a low fiber density can be easily crushed. can do. Thereby, when pressure is applied to the massive fiber layer, the voids of the protruding fiber portion are appropriately contracted to become a cushion, and the pressure can be appropriately absorbed, thereby preventing the pressure from being more applied to the core portion. be able to.

In the absorbent article according to the present invention, (4) the specific volume ratio is 0.2 or more and 0.7 or less when the pressure applied to the massive fiber layer is 25 g / cm ^2. The absorbent article according to any one of 3) may be used.
In the present absorbent article, the specific volume ratio at a pressure of 25 g / cm ² is 0.2 to 0.7. When the specific volume ratio is in this range, when pressure is applied to the massive fiber layer, the voids of the protruding fiber portion can be appropriately contracted. Therefore, in the protruding fiber portion, the fiber density is increased, and the high-viscosity excreted liquid in the void of the protruding fiber portion is prevented from seeping out. Further, in the core portion, the protruding fiber portion serves as a cushion and absorbs pressure appropriately, so that pressure is hardly applied to the core portion, and high-viscosity excreted liquid in the void of the core portion is suppressed from seeping out. . At this time, if the ratio of the load specific volume is less than 0.2, the contraction of the protruding fiber portion due to the pressure is too large, and the high-viscosity excretion liquid is likely to exude mainly from the protruding fiber portion. When the ratio of the load specific volume is more than 0.7, the contraction of the protruding fiber portion due to the pressure is too small, and the high-viscosity excreted liquid is likely to seep out mainly from the core portion.

(5) The absorbent article according to any one of the above (1) to (4), wherein the fibers constituting each of the plurality of mass fibers are not thermally fused. May be.
In the present absorbent article, since the fibers of the massive fibers are not heat-sealed, when pressure is applied to the absorbent article, the fibers in the protruding fiber portion can easily shrink, and the pressure is more applied to the core portion. Can be prevented from joining. In addition, when the voids of the protruding fiber portions and the voids between the core portions expand by absorbing the high-viscosity excreted liquid, it is possible to suppress the intersection of the fibers from hindering the expansion.

In the absorbent article of the present invention, (6) the first void when the pressure applied to the massive fiber layer is 3 g / cm ² , where the percentage of voids between the cores in the massive fiber layer is a porosity. (1) to (5), wherein the second porosity is 2% to 60% when the pressure applied to the massive fiber layer is 25 g / cm ^2. The absorbent article according to any one of the above.
In the present absorbent article, the first porosity of the massive fiber layer is 40% to 80%, and the second porosity is 2% to 60%. When the pressure is hardly applied to the massive fiber layer (3 g / cm ² ), the porosity is 40% to 80%, so that the pressure is buffered while securing a sufficient core portion to capture the high-viscosity excreted liquid. Sufficient protruding fiber portion can be secured. In addition, since the porosity when pressure is applied to the massive fiber layer (25 g / cm ² ) is 2% to 60%, it is necessary to secure a sufficient protruding fiber portion to hold the high-viscosity excreted liquid, The fiber portion can be sufficiently shrunk, and the application of pressure to the core portion can be suppressed. Here, if the porosity of the massive fiber layer at a pressure of 3 g / cm ^{2 is} less than 40%, a void capable of appropriately shrinking when the pressure is increased cannot be secured in the protruding fiber portion, and exceeds 80%. In such a case, it is not possible to secure a void in the core portion capable of sufficiently absorbing the high-viscosity excreted liquid. When the porosity of the massive fiber layer at a pressure of 25 g / cm ^{2 is} less than 2%, a void capable of sufficiently retaining the high-viscosity excreted liquid cannot be secured in the protruding fiber portion, and when the porosity is more than 60%, It becomes difficult to hold the high-viscosity excretion liquid in the void of the protruding fiber portion.

In the absorbent article of the present invention, (7) the basis weight of the adhesive between the massive fiber layer and the topsheet is greater than the basis weight of the adhesive between the massive fiber layer and the absorbent core. The absorbent article according to any one of the above (1) to (6) may be low.
In the present absorbent article, the basis weight of the adhesive (for example, hot melt adhesive) between the massive fiber layer and the topsheet is lower than the basis weight of the adhesive between the massive fiber layer and the absorbent core. Therefore, it is possible to suppress a situation in which the space of the massive fiber layer cannot be used for absorbing and transferring the high-viscosity excreted liquid by the adhesive. Thereby, the massive fiber layer can quickly capture and retain the high-viscosity excreted liquid. Further, since the basis weight of the adhesive between the absorbent core and the bulk fiber layer is relatively large, the contact area with the absorbent core increases, and the water content of the highly viscous excreted liquid is added to the absorbent core having high hydrophilicity. Easy to migrate.

(8) The absorbent article according to any one of (1) to (7), wherein (8) at least a part of the topsheet has a plurality of through holes penetrating in the thickness direction toward the massive fiber layer. The absorbent article according to any one of the above items.
In the present absorbent article, since the topsheet does not hinder the permeation of the high-viscosity fluid, the high-viscosity fluid can be transferred to the bulk fiber layer more quickly. However, the plurality of through-holes include not only the through-holes formed as holes, but also gaps between sheet fibers as if the surface sheet had a small basis weight and the through-holes were open.

The absorbent article of the present invention may be (9) the absorbent article according to any one of the above (1) to (8), wherein the lumped fibers are fiber balls.
In the present absorbent article, since the lump fibers are formed of fiber balls, lump fibers and lump fiber layers having a predetermined core portion and protruding fiber portions can be easily formed.

  ADVANTAGE OF THE INVENTION According to this invention, the absorptive article which can suppress the exudation (rewet) of a high-viscosity excretion liquid to a surface sheet can be provided, maintaining or improving the absorption performance with respect to a high-viscosity excretion liquid.

It is a perspective view showing the example of composition of the disposable diaper concerning an embodiment. It is a top view which shows the state which unfolded the disposable diaper of FIG. FIG. 2 is an exploded perspective view of the disposable diaper of FIG. 1. It is a figure which shows the example of a structure of the absorber of the disposable diaper of FIG. It is a schematic diagram which shows the structural example of the massive fiber and the massive fiber layer of the absorber of FIG. It is a schematic diagram which shows the example of a structure of the manufacturing apparatus of the absorber which concerns on embodiment. It is a figure which shows the other example of a structure of the absorber of the disposable diaper of FIG. It is a figure which shows the further another example of a structure of the absorber of the disposable diaper of FIG. It is a figure which shows the further another example of a structure of the absorber of the disposable diaper of FIG. It is the optical microscope photograph and the binarization processing image of the lump fiber of an absorber. It is a graph which shows the relationship between the load in a massive fiber layer, and specific volume. It is a graph which shows the relationship between the load in a massive fiber layer, and a specific volume ratio.

  Hereinafter, with respect to the absorbent article according to the embodiment, a pants-type disposable diaper (hereinafter, also simply referred to as “disposable diaper”) will be described as an example of the absorbent article. However, the present invention is not limited to the examples, and can be applied to various absorbent articles without departing from the scope of the subject of the present invention. Examples of such absorbent articles include tape-type disposable diapers, urine absorbing pads, stool pads, sanitary napkins, and the like.

First, a disposable diaper 1 according to the present embodiment will be described.
1 to 3 are views showing a configuration example of a disposable diaper 1 according to the present embodiment. However, FIG. 1 is a perspective view showing a state when the disposable diaper 1 is used, FIG. 2 is a plan view showing a state where the disposable diaper 1 is developed, and FIG. 3 shows a state where the disposable diaper 1 is disassembled. It is a perspective view. 2 and 3, the disposable diaper 1 has a longitudinal direction L, a width direction W, and a thickness direction T that are perpendicular to each other, and extends through the center of the width direction W and extends in the longitudinal direction L. It has a direction center line CL and a width direction center line CW extending in the width direction W through the center of the longitudinal direction L. Further, the direction toward and away from the longitudinal center line CL is defined as the inner direction and the outer direction in the width direction W, respectively. The direction toward and away from the width direction center line CW is defined as the inside direction and the outside direction of the longitudinal direction L, respectively. Viewing the disposable diaper 1 placed on a plane including the longitudinal direction L and the width direction W from above in the thickness direction T is referred to as “plan view”, and the shape grasped in plan view is referred to as “plan shape”. . The “skin side” and “non-skin side” mean a side relatively closer to the wearer's skin surface and a side farther from the skin surface in the thickness direction T of the disposable diaper 1 when the disposable diaper 1 is worn. These directions and the like are similarly applied to each material constituting the disposable diaper 1.

  The disposable diaper 1 includes an abdominal part 11, a dorsal part 13, and an intermediate part 12 between the abdominal part 11 and the dorsal part 13. The abdominal part 11 is a part of the disposable diaper 1 that is applied to the abdomen of the wearer. The intermediate portion 12 is a portion of the disposable diaper 1 which is applied to a crotch portion of a wearer. The back side portion 13 is a portion of the disposable diaper 1 that is applied to the buttocks and / or back of the wearer. Both ends 11a, 11b of the abdominal part 11 in the width direction W and both ends 13a, 13b of the back part 13 in the width direction W overlap each other in the thickness direction T along the longitudinal direction L. At the joints 14a and 14b. Further, in the disposable diaper 1, an end 11e of the abdominal portion 11 opposite to the intermediate portion 12 in the longitudinal direction L, and an end portion 13e of the dorsal portion 13 opposite to the intermediate portion 12 in the longitudinal direction L are provided. Thereby, the waist opening WO is formed. Further, in the disposable diaper 1, a pair of leg openings LO, LO is formed by both sides 12a, 12b in the width direction W of the intermediate part 12.

  The disposable diaper 1 includes an absorbent body 10 that absorbs and retains excrement, and a cover sheet 3 and a cover sheet 6 that retain the absorbent body 10 from the non-skin side and the skin side. The cover sheet 3 and the cover sheet cover both sides of the absorbent main body 10 in the thickness direction T, and extend around the width direction W and the longitudinal direction L of the absorbent main body 10. In order to expose the skin-side surface of the absorbent main body 10 to the cover sheet 6 on the skin side, a substantially rounded rectangular (or oval or oval type) is formed at a substantially central portion in the width direction W and the longitudinal direction L. An opening 6a is provided so that the excrement can be absorbed smoothly. The absorbent main body 10 is located between the top sheet 2 and the back sheet 8 and has a liquid absorbing property and a liquid retaining property. And an absorber 4. The absorber 4 has a configuration in which an absorbent core 4a located on the non-skin side and a massive fiber layer 4b located on the skin side are stacked in the thickness direction T.

As a material of the top sheet 2, the back sheet 8, the absorbent core 4a of the absorber 4, the cover sheet 3 and the cover sheet 6, known materials generally used in the disposable diaper 1 can be used. That is, examples of the material of the topsheet 2 include a liquid-permeable nonwoven fabric, a synthetic resin film having liquid-permeation holes formed thereon, and a composite sheet thereof. Examples of the material of the nonwoven fabric include natural fibers, regenerated fibers, inorganic fibers, and synthetic resin fibers. The basis weight of the topsheet 2 is, for example, ² to 100 g / m ² , preferably 5 to 50 g / m ² , and more preferably 8 to 20 g / m ² from the viewpoint of facilitating the permeation of the highly viscous excreted liquid. Examples of the back sheet 8 include a liquid-impermeable nonwoven fabric, a synthetic resin film, a composite sheet thereof, and an SMS nonwoven fabric. Examples of the material of the absorbent core 4a of the absorbent body 4 include hydrophilic fibers such as pulp fibers and synthetic fibers, and highly absorbent polymers (SAP). The basis weight of the fibers of the absorbent core 4a is, for example, 50 to 1000 g / m ² , and the basis weight of the superabsorbent polymer is, for example, 10 to 500 g / m ² . The massive fiber layer 4b of the absorber 4 will be described later. As the material of the cover sheet 3, for example, the same material as that of the top sheet 2 can be used. As the material of the cover sheet 6, for example, the same material as that of the back sheet 8 can be used. The absorbent main body 10, the cover sheet 3 and the cover sheet 6 are respectively bonded with an adhesive, and the absorber 4 and the top sheet 2 and the back sheet 8 are respectively bonded with an adhesive. As the adhesive, a known material, for example, a hot melt adhesive can be used.

  The disposable diaper 1 may include a pair of leak-proof walls 7a, 7b that are impermeable to liquid and an elastic body 9 (9a, 9b, 9c, 9d). The pair of leakage prevention walls 7a and 7b extend along the longitudinal direction L on both sides in the width direction W on the skin-side surface of the topsheet 2, and are arranged apart from each other in the width direction W. Each of the pair of leakage prevention walls 7a and 7b has a fixed outer end in the width direction W fixed to the topsheet 2 by heat welding or the like, and an inner end in the width direction W which can be stretched and gathered. Are formed as free ends. A plurality of elastic bodies 7Ea and 7Eb such as thread rubbers extending along the longitudinal direction L are respectively arranged near the free ends of each of the pair of leakage prevention walls 7a and 7b. The elastic body 9a and the elastic body 9b extend in the width direction W between the cover sheet 3 and the cover sheet 6 on the abdominal part 11 and the back part 13, respectively, are arranged at intervals in the longitudinal direction L, and are narrow. Be held. The elastic bodies 9a and 9b expand and contract the waist opening WO. The elastic bodies 9c and 9d are formed so as to substantially extend along the longitudinal direction L at both ends in the width direction W of the abdominal part 11 and the back part 13 side of the intermediate part 12, and to have a width at the central part of the intermediate part 12. They are arranged continuously along the direction W. The elastic bodies 9c and 9d extend and contract the pair of leg openings LO and LO, respectively. As the elastic body 9, for example, thread rubber can be used.

  Next, the absorber 4 will be further described. FIG. 4 is a diagram illustrating a configuration example of the absorbent body 4 of the disposable diaper 1. 4A is a plan view of the absorber 4, and FIG. 4B is a cross-sectional view of the absorber 4 taken along line IVb-IVb. As described above, the absorbent core 4 has the absorbent core 4a located on the non-skin side (back sheet 8 side) and the massive fiber layer 4b located on the skin side (top sheet 2 side) in the thickness direction T. It is configured to be laminated on. In the present embodiment, the massive fiber layer 4b covers the entire surface of the absorbent core 4a on the top sheet 2 side. The absorbent core 4a has a liquid absorbing property and a liquid retaining property, and mainly absorbs and retains liquid excrement such as urine. The massive fiber layer 4b absorbs and retains excrement including solid components such as loose stool and liquid components. However, a part of the liquid component is absorbed and held by the absorbent core 4a. In the present embodiment, the absorbent core 4a has an absorbent core body 4a-1 and a core wrap 4a-2 that covers the absorbent core body 4a-1. The material of the core wrap 4a-2 is, for example, a tissue.

Here, when the porous particle layer of Patent Literature 1 is used as the massive fiber layer 4b, it is effective for absorbing and retaining liquid excreta that is easily separated into a solid component and a liquid component. It is not necessarily effective for high-viscosity liquid excretions that are difficult to separate, ie, high-viscosity excretions. The reason is that when the porous particle layer absorbs high-viscosity excreted liquid, it absorbs and retains not only solid components but also liquid components. This is because the excreted liquid may leak to the outside. In this case, the leaked high-viscosity liquid exudes to the topsheet and causes rewet.
Therefore, in the disposable diaper 1 of the present embodiment, a layer including a plurality of lumped fibers having a predetermined configuration is used as the lumped fiber layer 4b of the absorber 4. Such a lump fiber layer 4b can appropriately absorb and hold the high-viscosity excreted liquid, and can appropriately prevent the internal high-viscosity excreted liquid from leaking out even when pressure is applied from the outside. The high-viscosity excretory liquid includes, for example, loose stool of a baby before a baby food. Hereinafter, a specific description will be given.

  FIG. 5 is a schematic diagram illustrating a configuration example of the massive fiber layer 4b and the plurality of massive fibers 40 in FIG. FIG. 5A shows a configuration example of the bulk fiber 40, and FIG. 5B shows a configuration example of the bulk fiber layer 4b. The massive fiber layer 4b includes a plurality of massive fibers 40. As shown in FIG. 5A, the lump fiber 40 is formed of lump fibers that are in a state of a three-dimensional lump as a whole while a plurality of fibers are entangled, and has a high fiber density and is hard to collapse. It includes a portion 41 and a protruding fiber portion 42 formed of crimpable fibers protruding outward from the periphery of the core portion 41 and having a low fiber density and easily crushable. Then, as shown in FIG. 5B, in the massive fiber layer 4b, the adjacent massive fibers 40 are in contact with each other via the protruding fiber portions 42.

The disposable diaper 1 provided with the massive fiber layer 4b has the following effects.
In the lump fiber layer 4b, the adjacent lump fibers 40 are in contact with each other via the protruding fiber portions 42, and the fibers of the protruding fiber portions 42 are entangled while repelling each other. A void (a void between the core portions 41) is formed by the 42 fibers. At this time, since the fibers of the protruding fiber portion 42 are composed of crimpable fibers and have a relatively low fiber density, when a pressure (load) is applied to the massive fiber layer 4b, the fibers are easily formed according to the pressure. Can shrink. Therefore, since the protruding fiber portion 42 contracts and absorbs the pressure, the influence of the pressure on the core portion 41 can be reduced, and the deformation of the core portion 41 can be suppressed.
Here, when pressure is applied to the massive fiber layer 4b, the specific volume of the massive fiber layer 4b decreases. However, as a mode of the decrease, first, when the pressure is small, the specific volume is reduced by mainly shrinking the protruding fiber portion 42 which is low in fiber density and easy to shrink due to many voids. When the pressure is large, after the contraction of the protruding fiber portion 42 has sufficiently progressed, the specific volume is further reduced by mainly contracting the core portion 41 having a small amount of voids and being difficult to contract. Accordingly, as the specific volume of the massive fiber layer 4b decreases, the contraction of the protruding fiber portion 42 and the contraction of the core portion 41 progress substantially stepwise.

When such a disposable diaper 1 absorbs a high-viscosity excreted liquid having a property that is difficult to separate into a solid component and a liquid component, the voids and projecting fibers in the core portion 41 of the massive fibers 40 in the massive fiber layer 4b. High-viscosity excretion liquid can be captured and retained in the voids in the portion 42. At this time, since the core portion 41 having the highest fiber density in the massive fiber layer 4b has a high fiber density, when there is room for capacity, the high-viscosity excreted liquid once held in the protruding fiber portion 42 is discharged to the protruding fiber portion 42. Can be absorbed and retained from the portion adjacent to the
Furthermore, when pressure is applied to the disposable diaper 1 due to a change in the posture of the wearer in a state where the disposable diaper 1 holds the high-viscosity excrement, the crimping fibers of the protruding fiber portion 42 are changed according to the pressure. By contracting and becoming a cushion, the pressure can be absorbed. Therefore, the pressure can be hardly applied to the core portion 41. Thereby, it is possible to make it difficult for the high-viscosity excreted liquid held in the gap in the core portion 41 to be pushed out. Furthermore, by reducing the distance between the bulk fibers 40 and increasing the fiber density of the voids of the protruding fiber portions 42, that is, by increasing the fiber density around the core portion 41, it is possible to suppress leakage from the core portion 41. Can be. By these, the surface return rate, which is the rate at which the high-viscosity excreted liquid once absorbed returns to the topsheet 2 side, can be reduced, and the retention rate, which is the rate remaining in the massive fiber layer 4b, can be increased.

  Here, when a large amount of the high-viscosity excretion liquid is held in the space of the protruding fiber portion 42, the high-viscosity excretion liquid held in the space of the protruding fiber portion 42 is contracted by the contraction of the protruding fiber portion 42. Can easily be pushed out. However, since the high-viscosity excretion liquid has moved below the protruding fiber part 42 (toward the absorbent core 4a) by its own weight, it is covered with the protruding fiber part 42 above (to the top sheet 2). In other words, it is in a state of being covered upward. As a result, even if the gap of the protruding fiber portion 42 shrinks, the lid (upper protruding fiber portion 42) can prevent the high-viscosity excreted liquid from leaking to the topsheet 2 side. In addition, the high-viscosity excreted liquid having nowhere to go is placed in the voids of the core fibers 41 and the protruding fiber portions 42 of the mass fibers 40 where no load is applied (for example, a crevices of the buttocks), and the protruding fibers of the protruding fiber 40 in the middle. It can be moved via the part 42. Thereby, it is hard to be pushed out. In the case of liquid excrement that has a property of being easily separated into a solid component and a liquid component, the solid component can be mainly absorbed by the massive fiber layer, and the liquid component can be mainly absorbed by the absorbent core. In the case of liquid excrement that has a property of being easily separated into a solid component and a liquid component, the solid component can be mainly absorbed by the massive fiber layer, and the liquid component can be mainly absorbed by the absorbent core.

  With such a disposable diaper 1, it is possible to further suppress the seepage of the high-viscosity excrement into the topsheet 2 while maintaining or improving the absorption performance for the high-viscosity excretion.

  However, the fact that the fiber density of the core 41 is relatively high and the fiber density of the protruding fiber 42 is relatively low can be confirmed, for example, by the following method. That is, a 360-degree scan of a massive fiber or a massive fiber layer is performed using the X-ray fluoroscope FLEX-M863. Specifically, every time the sample is rotated by 0.2 degrees, an X-ray fluoroscopic image is taken, 360 degrees, that is, 1800 X-ray fluoroscopic images are acquired, and the acquired 1800 X-ray fluoroscopic images are connected. In addition, a 3D image is created. Then, regions of the same volume of the core portion 41 and the protruding fiber portion 42 were respectively extracted from the 3D image, and the approximate number of fibers was measured from each of the extracted regions and compared.

Here, it is important that the massive fiber layer 4b has the following configuration.
The specific volume of the massive fiber layer 4b when a pressure (load) of 3 g / cm ² is applied to the massive fiber layer 4b is defined as a reference specific volume (unit: cc / g). The specific volume of the massive fiber layer 4b when a pressure greater than 3 g / cm ² is applied to the massive fiber layer 4b is defined as a load specific volume (unit: cc / g). The ratio of the load specific volume to the reference specific volume is defined as a specific volume ratio (unit: dimensionless). The ratio of the change in the specific volume ratio to the change in the pressure applied to the massive fiber layer 4b is defined as a rate of change (unit: (g / cm ² ) ⁻¹ ). At that time, the lump-shaped fiber layer 4b of the disposable diaper 1 having the above-described functions and effects has the following configuration. The first rate of change, which is the rate of change when the pressure (load) applied to the lump fiber layer 4b is 3 g / cm ² to 5 g / cm ² , is −0.12 (g / cm ² ) ⁻¹ or more, −0 0.025 (g / cm ² ) ^-1 or less. Preferably, the first rate of change is −0.10 (g / cm ² ) ⁻¹ or more and −0.030 (g / cm ² ) ⁻¹ . And the second rate of change, which is the rate of change when the pressure (load) applied to the massive fiber layer 4b is 25 g / cm ² to 30 g / cm ² , is −0.02 (g / cm ² ) ⁻¹ or more, 0 (g / cm < ² >) < ^-1 . Preferably, the second rate of change is -0.01 (g / cm ² ) ^-1 or more and -0.005 (g / cm ² ) ^-1 or less. Here, the state in which a pressure of 3 g / cm ² is applied to the lump fiber layer 4b simulates a state in which almost no pressure is applied to the disposable diaper 1 in which the wearer is standing, and the lump fiber layer 4b has a pressure of 25 g / cm 2. ^The state in which the pressure of 2 is applied simulates a state in which a relatively large pressure is applied to the disposable diaper 1 in which the wearer is sitting. Then, from 3 g / cm ² pressure (load) changes in 5 g / cm ² corresponds to the shrinkage variation of the projecting fiber portion 42, from 25 g / cm ² change of pressure (load) of 30 g / cm ² is of the core portion 41 Corresponds to shrinkage change.

When the first rate of change is less than −0.12 (g / cm ² ) ^{−1, the} specific volume ratio is excessively reduced due to the contraction of the protruding fiber portion 42 with respect to the change in the pressure applied to the massive fiber layer 4 b (protrusion). Since there are many voids in the fiber portion 42 or the amount of fiber in the protruding fiber portion 42 is small, etc.), the retained high-viscosity excreted liquid is easily released. On the other hand, when the first rate of change exceeds −0.025 (g / cm ² ) ⁻¹ , the decrease in the specific volume ratio due to the contraction of the protruding fiber portion 42 with respect to the change in the pressure applied to the massive fiber layer 4 b is too small (protrusion). The voids in the fiber portions 42 are small, or the amount of fibers in the protruding fiber portions 42 is large, etc.), so that it becomes difficult to sufficiently retain the high-viscosity excreted liquid. When the second rate of change is less than −0.02 (g / cm ² ) ⁻¹ , that is, when the absolute value exceeds 0.015, the specific volume due to the contraction of the core portion 41 with respect to the change in the pressure applied to the massive fiber layer 4 b. Since the decrease in the ratio is too large (the voids in the core portion 41 are large, or the amount of fibers in the core portion 41 is small, etc.), the core portion 41 is easily deformed, and the high-viscosity excreted liquid easily leaks out.

The specific volume of the massive fiber layer 4b is appropriately set according to the required absorption amount of the highly viscous excreted liquid. In the present embodiment, when the pressure (load) applied to the massive fiber layer 4b is 3 g / cm ² , the specific volume of the massive fiber layer 4b is, for example, 50 to 90 cc / g, and the pressure (load) is 25 g / cm ^2. In the case of cm ² , the specific volume is, for example, 20 to 35 cc / g. However, when the specific volume of the massive fiber layer 4b is relatively small, the fiber density of the massive fiber layer 4b is relatively high, and the absorption amount of the high-viscosity waste liquid is relatively small. Release tends to be difficult.

  The size of the core portion 41 and the bulk fibers 40 is appropriately set according to the required absorption amount of the high viscosity excreted liquid. In the present embodiment, the shapes of the core portion 41 and the lump fiber 40 are lump and not spherical, and the shape of the protruding fiber portion 42 covering the outer peripheral surface of the core portion 41 is not a uniform thickness. Therefore, in the present embodiment, the core portion 41 and the massive fiber 40 are regarded as spheres, and the protruding fiber portion 42 is regarded as a layer having a uniform thickness covering the outer peripheral surface of the core portion 41. At this time, the average radius r of the core portion 41 is, for example, in the range of 0.1 to 0.5 cm (for example, the diameter 2r is in the range of 0.2 to 1 cm). The average thickness d of the protruding fiber portion 42 is, for example, in the range of 0.2 to 0.6 cm. Accordingly, the average radius (r + d) of the massive fiber 40 is, for example, in a range of 0.3 to 1.1 cm (the diameter 2 × (r + d) is in a range of, for example, 0.6 to 2.2). However, when the diameter of the core portion 41 is relatively large, the absorption amount of the high-viscosity excreted liquid that can be stably held becomes relatively large, but tends to be easily affected by the body pressure of the wearer. If the thickness of the protruding fiber portion 42 is relatively large, the absorption amount of the high-viscosity excreted liquid that can be stably held becomes relatively small, but tends to be less affected by the wearer's body pressure.

As a preferable mode in the present embodiment, the ratio (d / 2r) of the thickness d of the protruding fiber portion 42 to the diameter 2r of the core portion 41 is in the range of 0.4 to 2, and 0.7 to 1.0. A range of 5 is more preferred. That is, the average thickness d of the protruding fiber portion 42 on the surface of the core portion 41 in the bulk fiber 40 is preferably 0.4 times or more and 2 times or less the average diameter 2r of the core portion 41, and more preferably 0.7 times or more. 1.5 times or less is more preferable. As described above, when the average thickness d of the protruding fiber portion 42 is in the above range, the high-viscosity excreted liquid can be held more appropriately in the gap of the protruding fiber portion 42, and pressure is applied to the massive fiber layer 4b. When this occurs, the gap of the protruding fiber portion 42 shrinks more appropriately, and the pressure can be more appropriately absorbed. Thereby, the pressure can be prevented from being applied to the core portion 41 more.
Here, when the average thickness d of the protruding fiber portion 42 is set to less than 0.4 times the average diameter 2r of the core portion 41, the space of the protruding fiber portion 42 cannot be sufficiently secured, and pressure is applied to the core portion 41. It becomes easy to exude the highly viscous excreted liquid from the core portion 41. When the average thickness d of the protruding fiber portion 42 is more than twice the average diameter 2r of the core portion 41, the protruding fiber portion 42 contracts in a state where a large amount of high-viscosity excreted liquid is held in the protruding fiber portion 42. As a result, the high-viscosity excreted liquid easily leaks out from the protruding fiber portion 42.

The mass of one lump fiber 40 and the number of lump fibers 40 per 1 cm ^{3 of the} lump fiber layer 4b are appropriately set according to the required absorption amount of the high viscosity excreted liquid. In the present embodiment, the mass per one piece of the lump fiber is, for example, 0.5 to 8 mg / piece. The number of the clumped fibers 40 per 1 cm ^{3 of the} clumped fiber layer 4b (with no load) is, for example, 2.5 to 30 / cm ³ . However, if the mass per one of the bulk fibers 40 or the number of the bulk fibers 40 per 1 cm ^{3 of the} bulk fiber layer 4b is relatively large, the absorption amount of the highly viscous excreted liquid becomes relatively large.

In a preferred mode in the present embodiment, the specific volume ratio at a pressure applied to the massive fiber layer 4b of 25 g / cm ² is 0.2 or more and 0.7 or less, and 0.3 or more and 0.6 or less. More preferred.
When the specific volume ratio at a pressure of 25 g / cm ² is within this range, when pressure is applied to the massive fiber layer 4b, the voids of the protruding fiber portion 42 can be more appropriately contracted. As a result, in the protruding fiber portion 42, the fiber density of the protruding fiber portion 42 becomes sufficiently high, and it is possible to further suppress the high-viscosity excreted liquid in the void of the protruding fiber portion 42 from seeping out. Further, in the core portion 41, the protruding fiber portion 42 serves as a cushion and absorbs the pressure more appropriately, so that the pressure is less likely to be applied to the core portion 41, and the highly viscous excreted liquid in the void of the core portion 41 permeates to the outside. Can be suppressed more. Here, if the ratio of the load specific volume is less than 0.2, the contraction of the protruding fiber portion 42 due to the pressure is too large, and the high-viscosity excreted liquid mainly easily leaks out from the protruding fiber portion 42. When the ratio of the load specific volume is more than 0.7, the contraction of the protruding fiber portion 42 due to the pressure is too small, so that the high-viscosity excreted liquid mainly leaks from the core portion 41 easily.

When the ratio of the voids between the core portions 41 in the massive fiber layer 4b is the porosity, the porosity when the pressure applied to the massive fiber layer 4b is 3 g / cm ² is the first porosity. The porosity when the applied pressure is 25 g / cm ² is defined as the second porosity. At this time, as a preferable mode in the present embodiment, the first porosity is 40% or more and 80% or less, and the second porosity is 2% or more and 60% or less. The first porosity is more preferably 50% or more and 80% or less, and the second porosity is more preferably 2% or more and 50% or less.
When the first porosity is in this range, that is, when the porosity is 40% to 80% when little pressure is applied to the massive fiber layer 4b (3 g / cm ² ), the high-viscosity excreted liquid is supplemented. In this case, it is possible to secure a sufficient protruding fiber portion 42 for buffering pressure while securing a sufficient core portion 41. When the second porosity is in this range, that is, when the porosity is 2% to 60% when the pressure is applied to the massive fiber layer 4b (25 g / cm ² ), the high-viscosity excreted liquid is retained. The protruding fiber portion 42 can be sufficiently shrunk while securing a sufficient protruding fiber portion 42 to prevent the pressure from being applied to the core portion 41. If the first porosity is less than 40%, it is not possible to secure an appropriately shrinkable void in the protruding fiber portion 42 when the pressure is increased, and if it is more than 80%, a void that can sufficiently absorb the high-viscosity excreted liquid. Cannot be secured in the core portion 41. Further, when the first porosity is less than 5%, it is not possible to secure a space capable of sufficiently retaining the high-viscosity excretion liquid in the protruding fiber portion 42, and when the first porosity exceeds 60%, the high-viscosity excretion liquid is not protruded. It will be difficult to hold in the gap of the part 42.

As another embodiment, at least a part of the topsheet 2 may have a plurality of through holes (not shown) penetrating in the thickness direction T toward the massive fiber layer 4b. The plurality of through holes extend from one surface of the topsheet 2 to the other surface, and function as holes through which not only liquid components but also solid components can pass. Therefore, the high-viscosity excretion liquid can pass through the topsheet 2 through the plurality of through holes. The plurality of through-holes preferably have a ratio of the total cross-sectional area of the through-holes to the area of the topsheet 2, that is, an opening ratio of 5 to 90%. The hole diameter of the through-hole is preferably smaller than the diameter of the bulk fibers 40 contained in the bulk fiber layer 4b, and the upper limit is preferably less than 1 cm, and the lower limit is not particularly limited, and is, for example, 0.08 cm or more. The number of through holes is preferably 0.3 to 30 / cm ² . When the basis weight is low (for example, 8 to 20 g / m ² ), the topsheet 2 can be said to be a topsheet 2 having a plurality of through holes since there are many voids.

  The lump fibers 40 contained in the lump fiber layer 4b are preferably made of fibers having hydrophilicity. Thereby, hydrophilicity can be given to the massive fiber layer 4b. Examples of the fiber having hydrophilicity include, for example, at least one of a hydrophilic fiber and a hydrophobic fiber subjected to a hydrophilic treatment. The hydrophilic fibers include, for example, fibers made of a hydrophilic material such as cotton and pulp, and the hydrophobic fibers include, for example, polyester fibers and polyolefin fibers. The hydrophilic treatment is, for example, a treatment using a surfactant or a hydrophilic agent. Is mentioned. The lump fibers 40 may include hydrophobic fibers as long as hydrophilicity can be maintained. Since the massive fiber layer 4b has hydrophilicity, excrement can be efficiently transmitted, absorbed, and held. In the present embodiment, as a preferred mode, the massive fiber 40 is a fiber ball. A fiber ball is a mass of fibers having a shape that is relatively close to a sphere in appearance. By forming the clumped fiber 40 with a fiber ball, the clumped fiber 40 and the clumped fiber layer 4b having the predetermined core portion 41 and the protruding fiber portion 42 can be easily formed.

  When a fiber ball is used as the clumped fiber 40, a fiber ball manufactured using a conventionally known method may be used, or a commercially available product may be used. As a method for producing a fiber ball, for example, a method of entangled fibers and granulating them (for example, JP-A-2006-94692), a method of heat-sealing or thermally shrinking the fibers to granulate (for example, JP-A-2000-2000) JP-A-345457, JP-A-7-39659, and the like, and a method of granulating using a binder (for example, JP-A-63-50373 and JP-A-11-105030). For example, Japanese Patent Application Laid-Open No. 2006-94692 discloses that heat-welding fibers and / or fibers having no heat-sealing properties or hardly heat-welding fibers are rotated by rotation of air in a truncated cone-shaped container in which air rotates. A method of three-dimensionally rotating and rolling into a fiber ball is disclosed. Japanese Patent Application Laid-Open No. 2000-345457 discloses that a heat-adhesive conjugate fiber containing a thermoplastic elastomer as a heat-adhesive component and a polyester-based main fiber having high dry heat shrinkage are combined with a fiber ball while heat-shrinking the main fiber. A production method for molding the same is disclosed. Further, Japanese Patent Application Laid-Open No. 7-39659 discloses that a plurality of synthetic fiber crimped yarns are aligned and bunched, then cut, and then heat-treated at a temperature lower than the melting point of the synthetic fiber crimped yarn. There is disclosed a method of producing a fiber ball by expressing crimp of a processed yarn. In each of these methods, for example, by controlling the molding conditions and the heat treatment conditions, it is possible to form the massive fiber 40 which is a fiber ball having the core 41 and the protruding fiber 42.

  For production of the fiber ball, a commercially available fiber ball production apparatus (for example, a granulating apparatus Ball Fibers Forming Machine CMM1 manufactured by Massias) can be used. Examples of the fiber ball manufactured by the fiber ball manufacturing apparatus include a fiber ball obtained by molding a thermoplastic resin fiber (eg, polyester fiber) into a fiber ball. When molding thermoplastic resin fibers into fiber balls, crimpable fibers are used as the fibers in the fiber balls. Thus, a fiber ball can be formed in which the protruding fiber portion easily contracts when the pressure is applied, and can easily expand when the pressure is released. For example, by controlling molding conditions and the like, it is possible to form the massive fiber 40 which is a fiber ball having the core 41 and the protruding fiber 42.

  In a preferred embodiment of the present embodiment, the fibers of the core portion 41 and the fibers of the protruding fiber portion 42 of the bulk fiber 40 are the same. Therefore, since the fibers are continuously connected from the core portion 41 to the protruding fiber portion 42, the high-viscosity excreted liquid can be supplemented by the protruding fiber portion 42 and guided to the core portion 41 more easily. At the same time, the predetermined protruding fiber portion 42 and the core portion 41 can be formed more accurately, so that the core portion having a high fiber density can be hardly crushed, and the protruding fiber portion having a low fiber density can be easily crushed. be able to. Thereby, when pressure is applied to the massive fiber layer, the voids in the protruding fiber portion are appropriately contracted to become a cushion, and the pressure can be appropriately absorbed, so that pressure is not more applied to the core portion. Can be.

  In a preferred embodiment of the present embodiment, the fibers constituting each of the plurality of bulk fibers 40 are not thermally fused. This allows the fibers to easily contract and expand in response to the application and release of pressure. When pressure is applied to the disposable diaper 1, the fibers of the protruding fiber portion 42 can be easily contracted, and pressure can be hardly applied to the core portion 41. Further, when the voids of the protruding fiber portions 42 and the voids between the core portions 41 expand by absorbing the high-viscosity excreted liquid, it is possible to suppress the intersections of the fibers from hindering the expansion.

  In addition, some or all of the fibers constituting each of the plurality of massive fibers 40 may be joined. In that case, compression resistance or compression resilience can be imparted to the bulk fibers 40. Examples of the joining method include a method of thermally fusing fibers to each other and a method of bonding fibers to each other (a binder fiber, an adhesive, or the like). Thereby, when the disposable diaper 1 is used (for example, body pressure of the wearer), a decrease in the specific volume (porosity) of the massive fiber layer 4b and a decrease in the absorption / holding performance of the massive fiber layer 4b due to this are suppressed. it can.

An adhesive (eg, a hot melt adhesive) is preferably applied to the interface between the massive fiber layer 4b and the topsheet 2 and / or the interface between the massive fiber layer 4b and the absorbent core 4a. Thereby, the lump fibers 40 contained in the lump fiber layer 4b can be fixed. From the viewpoint of permeation of excretory fluid including high-viscosity excretory fluid, the adhesive is preferably not applied to the entire interface but is applied in a pattern such as a dot, a spiral, or a stripe. Examples of the method for applying the adhesive include spiral coating, coater coating, curtain coater coating, and summit gun coating. The coating amount (basis weight) of the adhesive is, for example, 3 to 100 g / m ² .

  In a preferred embodiment of the present embodiment, the basis weight of the adhesive between the massive fiber layer 4b and the topsheet 2 is lower than the basis weight of the adhesive between the massive fiber layer 4b and the absorbent core 4a. That is, since the basis weight of the adhesive between the massive fiber layer 4b and the topsheet 2 is relatively small, the space in the massive fiber layer 4b becomes difficult to use for absorbing and transferring high-viscosity excreted liquid by the adhesive. Can be suppressed. Thereby, the massive fiber layer 4b can quickly capture and hold the high-viscosity excreted liquid. Also, since the basis weight of the adhesive between the massive fiber layer 4b and the absorbent core 4a is relatively large, the contact area between the massive fiber layer 4b and the absorbent core 4a is increased, and the hydrophilicity is high. High-viscosity excretion liquid and other excrement moisture can be easily transferred to the core 4a.

The thickness, basis weight, and the like of the massive fiber layer 4b are appropriately adjusted according to the required absorption amount of the high-viscosity excreted liquid. In the present embodiment, the thickness of the massive fiber layer 4b is, for example, 1 to 10 mm. As the thickness of the massive fiber layer 4b is larger, the absorption amount of the highly viscous excreted liquid is increased, but the feeling of wearing tends to be reduced. The basis weight of the massive fiber layer 4b is, for example, 25 to 500 g / m ² . The larger the basis weight of the massive fiber layer 4b, the easier it is to hold the high-viscosity excreted liquid, but the feeling of wearing tends to be reduced. Note that the thickness, basis weight, and the like of the massive fiber layer 4b may be constant throughout or may be partially different.

  Next, a method for manufacturing the disposable diaper 1 according to the present embodiment will be described. FIG. 6 is a schematic diagram illustrating a configuration example of an absorber manufacturing apparatus according to the embodiment.

  The first step is a step of forming the absorbent core body 411. As shown in FIG. 6, a suction drum 110 that rotates in the transport direction MD and an absorbent material supply unit 120 that includes a hood that covers the suction drum 110 are used to form the absorbent core body 411. On the peripheral surface 111 of the suction drum 110, concave portions 112 are formed at a required pitch in the circumferential direction as a mold for filling the absorbent material. When the suction drum 110 rotates and the recess 112 enters the absorbent material supply unit 120, the suction unit 113 acts on the recess 112, and the absorbent material supplied from the absorbent material supply unit 120 is vacuum-sucked into the recess 112. You. The absorbent material supplied from the absorbent material supply unit 120 has a predetermined mass of the hydrophilic fiber F supplied from the pulverizer (not shown) and the superabsorbent polymer P supplied from the particle supply unit 121. It is contained in a mixing ratio. Thus, the absorbent core body 411 is formed in the concave portion 112. The absorbent core body 411 contains the hydrophilic fiber F and the superabsorbent polymer P in a mixed state. The absorbent core body 411 formed in the concave portion 112 is transferred onto the lower layer core wrap 91 that advances in the transport direction MD by the action of the transfer suction section 150. The upper surface of the lower core wrap 91 is coated with a hot-melt adhesive, and the absorbent core body 411 is joined onto the lower core wrap 91 by the hot-melt adhesive. The absorbent core main body 411 transferred to the lower layer core wrap 91 advances in the transport direction MD.

  The next step is a step of laminating the upper core wrap 92 on the absorbent core body 411 that proceeds in the transport direction MD. The lower surface of the upper core wrap 92 is coated with a hot melt adhesive, and the absorbent core body 411 is joined to the upper core wrap 92 by the hot melt adhesive. Thus, a continuous body of a laminated body in which the upper core wrap 92, the absorbent core main body 411, and the lower core wrap 91 are sequentially laminated is formed. The continuous body is cut into a predetermined shape by a pair of rolls 300 and 301, and an absorbent core 4a having an absorbent core body 4a-1 and a core wrap 4a-2 covering the absorbent core body 4a-1 is formed. It is formed.

  The next step is a step of applying an adhesive on the absorbent core body 4a-1. An adhesive application device 302 is used for applying the adhesive. The adhesive application device 302 applies, for example, a hot melt adhesive in a spiral pattern by, for example, a spiral coating method.

  The next step is a step of supplying a plurality of lumped fibers 40 to the adhesive-coated surface of the absorbent core 4a to form the lumped fiber layer 4b. A massive fiber supply device 303 is used to supply the plurality of massive fibers 40.

  Through the above steps, the absorber 4 having the absorbent core 4a and the massive fiber layer 4b laminated on one surface of the absorbent core 4a is manufactured. The production of the disposable diaper 1 using the absorber 4 can be performed according to a conventionally known method.

  In a preferred mode of the present embodiment, as shown in FIG. 4, in the absorbent body 4, the massive fiber layer 4b is provided so as to cover the entire skin-side surface of the absorbent core 4a. However, the configuration of the absorber 4 (lumped fiber layer 4b) is not limited to this example, and can be changed as appropriate.

  FIG. 7 is a diagram showing another configuration example of the absorbent body of the disposable diaper 1. As shown in FIG. FIG. 7A is a plan view of the absorber 4A, and FIG. 7B is a sectional view of the absorber 4A taken along the line VIIb-VIIb. In the absorber 4A, the massive fiber layer 4bA is provided on a part of a region corresponding to the middle portion 12 of the disposable diaper 1 on the skin side surface of the absorbent core 4a. The portion where the massive fiber layer 4bA is provided is, for example, a portion of the region corresponding to the middle portion 12 of the disposable diaper 1 which is located closer to the back portion 13 than the center. The absorber 4A can suppress the spread of the high-viscosity excretion discharged from the wearer and can absorb the high-viscosity excretion mainly in the massive fiber layer 4bA.

  FIG. 8 is a diagram showing still another configuration example of the absorbent body of the disposable diaper 1. As shown in FIG. FIG. 8A is a plan view of the absorber 4B, and FIG. 8B is a sectional view of the absorber 4B taken along the line VIIIb-VIIIb. In the absorbent body 4B, the massive fiber layer 4bB is provided on a part of a region corresponding to the middle portion 12 of the disposable diaper 1 on the skin side surface of the absorbent core 4a. The portion where the massive fiber layer 4bB is provided is, for example, in a region corresponding to the intermediate portion 12 of the disposable diaper 1, in a portion extending in the longitudinal direction L at both ends in the width direction W, on a side closer to the dorsal portion 13 than the center. It is the part located. The absorber 4B can prevent the high-viscosity excreted liquid excreted from the wearer from leaking over the pair of leak-proof walls 7a and 7b. Therefore, the absorbent body 4B is particularly useful as a diaper for relatively old babies who take a sideways posture or open and close the legs.

  FIG. 9 is a diagram showing still another configuration example of the absorbent body of the disposable diaper 1. As shown in FIG. FIG. 9A is a plan view of the absorber 4C, and FIG. 9B is a sectional view of the absorber 4C taken along the line IXb-IXb. In the absorber 4C, the massive fiber layer 4bC is provided in a part of the skin-side surface of the absorbent core 4a corresponding to the back side portion 13 of the disposable diaper 1. The absorber 4C can suppress the high-viscosity excreted liquid excreted from the wearer from flowing toward the back of the wearer. Therefore, the absorber 4C is particularly useful as a diaper for a relatively low-age baby who takes a good posture in a back-up sleeping position.

  Hereinafter, the present invention will be described in more detail based on examples, but the scope of the present invention is not limited to the examples.

(I) Preparation of sample <Lump fiber>
Lump fibers were produced in the following manner. Polyester fibers (fineness 7.4 T, fiber length 32 mm) whose surface is hydrophilized are processed into granular cotton by an airflow type granulating device (Ball Fibers Forming Machine CMM1 manufactured by Massias), and a lump fiber is formed depending on the molding conditions. AD were obtained.

<Top sheet>
A topsheet was produced in the following manner. A core-sheath composite fiber (core-sheath ratio 50:50 (cross-sectional area ratio), fineness 4.4 dtex, fiber length 51 mm) having polyethylene terephthalate (PET) as a core component and high-density polyethylene (HDPE) as a sheath component, The fiber to which the hydrophilic oil agent was adhered was subjected to carding treatment to produce a fibrous web (basis weight 10 g / m ² ). This fiber web was subjected to an air-through bonding treatment to produce an air-through nonwoven fabric (1.0 mm in thickness).

<Absorptive core>
The absorbent core was manufactured in the following manner. A fluffy pulp obtained by pulverizing fluff pulp (manufactured by International Paper: Super Soft) and a super absorbent polymer (manufactured by Sumitomo Seika Co., Ltd .: SA50) were mixed so that both were uniformly dispersed. Thereafter, the laminate is laminated to produce a laminate having a length of 300 mm, a width of 120 mm, a basis weight of the cotton-like pulp of 250 g / m ² ± 3%, and a basis weight of the superabsorbent polymer of 250 g / m ² ± 3%. did. The thus-produced laminate was sandwiched between two tissues each having a hot-melt adhesive applied to the surface on the laminate side, and then pressure-molded to a thickness of 2.5 mm with a pressure device.

<Production of Samples of Examples and Comparative Examples>
Samples of Examples 1 to 4 and Comparative Example 1 were produced by the following methods.
(1) Example 1: Above the central part of the above absorbent core, in a region of length 120 mm × width 100 mm, a plurality of lumpy fibers A were prepared such that the basis weight was 100 g / m ² ± 3%. Laminated. Then, a surface sheet coated with a hot melt adhesive in a pattern in which only the plurality of lump fibers were not bonded was bonded to the upper surface of the absorbent core.
(2) Example 2: The same as Example 1 except that the bulk fiber A was changed to the bulk fiber B.
(3) Example 3: Same as Example 1 except that the bulk fiber A was changed to the bulk fiber C.
(4) Example 4: Same as Example 1 except that the bulk fiber A was changed to the bulk fiber D.
(5) Comparative Example 1: The same as Example 1 except that the bulk fiber A was changed to a cotton ball (manufactured by Suzuran Co., Ltd .: lily of the valley cotton ball No. 3).

(II) Evaluation of Sample (II-1) Evaluation of Lumped Fiber First, for the lumped fibers of Examples 1 to 4 and Comparative Example 1, namely, lumped fibers A to D and cotton balls, the average core diameter 2r, lumped fiber The average diameter 2 × (r + d) and the average thickness d of the protruding fiber portion were determined by the following methods.

<Average core diameter 2r>
(I) Using a digital microscope VHX-2000 (Keyence Corporation), the lens magnification was set to a magnification at which the lump fiber to be measured enters the screen (for example, 20 to 200 times).
(Ii) The image size was set to 1600 pixels (H) × 1200 pixels (V).
(Iii) The lump fiber to be measured was set on the transmission measurement unit, and an image was taken.
(Iv) After saving and recalling the image, "measurement", "automatic area measurement", "luminance", and "start measurement" were selected.
(V) The binarization threshold value was set to 0, and the extraction parameters were binarized by checking "dark", "fill-in", and "removal of small particles".
(Vi) The area of the extraction region automatically calculated was recorded as the projected area of the massive fiber.
(Vii) The above (iii) to (vi) were performed on ten lumpy fibers, and the projected areas of the ten lumpy fibers were obtained. The average value Av of the projection areas of these ten projections was determined.
(Vii) The diameter 2r (approximate value) of the core portion 41 is calculated by (4 × Av / π) ^0.5 when the average value Av of the obtained projected areas is defined as the area of a circle. did.

<Average diameter of massive fiber 2 × (r + d)>
(I) Using a digital microscope VHX-2000 (Keyence Corporation), the lens magnification was set to a magnification at which the lump fiber to be measured enters the screen (for example, 20 to 200 times).
(Ii) The image size was set to 1600 pixels (H) × 1200 pixels (V).
(Iii) The lump fiber to be measured was set on the transmission measurement unit, and an image was taken.
(Iv) The image was saved and recalled, and the longest length (major axis) of the massive fiber was measured.
(V) The longest length (short diameter) of the lump fiber was measured under conditions perpendicular to the long diameter measurement line.
(Vi) The above (iii) to (v) were performed on ten lumpy fibers, and the major axis and minor axis of the ten lumpy fibers were determined. The average value r _L of the major axis and the average value r _S of the minor axis for these 10 pieces were determined.
(Vii) The average value (r _L + r _S ) / 2 of the obtained average value r _{L of the} major axis and the average value r _S of the minor axis is obtained, and the diameter 2 × (r + d) of the massive fiber (approximate value) ).

<Average thickness d of protruding fiber part>
(I) The diameter 2r (approximate value) of the core portion 41 is subtracted from the diameter 2 × (r + d) (approximate value) of the above-mentioned lump fiber, and the resulting value is reduced to 1/2, and the thickness of the protruding fiber portion 42 is reduced. d (approximate value) was calculated.

<Result>
An example of an image taken when calculating the average diameter 2r of the core portion, the average diameter 2 × (r + d) of the massive fiber, and the average thickness d of the protruding fiber portion, and an example of an image obtained by binarizing the image. , Shown in FIG. FIG. 10 is an optical microscope image of the lump fiber 40 in each of the samples of Examples 1 to 4 and Comparative Example 1, and an image obtained by binarizing and lowering the image. As shown in the figures, in each of the samples of Examples 1 to 4, the protruding fiber portion is present in a wide range around the core portion, but in the sample of Comparative Example 1, the protruding fiber portion is very slightly present. Turned out not to be. Table 1 below shows the results of calculating the average diameter 2r of the core portion and the average thickness d and d / 2r of the protruding fiber portion. As a range of d / 2r, it turned out that 0.4-2 is preferable and 0.7-1.5 is more preferable.

(II-2) Evaluation of each sample of Examples 1 to 4 and Comparative Example 1 For each sample of Examples 1 to 4 and Comparative Example 1, the specific volume, the specific volume ratio, and the rate of change of the specific volume ratio were determined by the following methods. I asked for it.

<Specific volume>
The following measurements were performed on each of the lump fibers A to D and the cotton balls of Examples 1 to 4 and Comparative Example 1.
(I) A plurality of lumped fibers, a total of 0.180 g (corresponding to 100 g / m ² ), were uniformly charged into a cylinder (diameter: 18 cm ² ) having a diameter of 48 mm to prepare a measurement sample. This measurement sample simulates the massive fiber layer 4b.
(Ii) Thickness measuring device: The thickness of the measurement sample at the center of the cylinder was measured with a dial thickness gauge large type JB (manufactured by Ozaki Seisakusho). At this time, a load of 3 g / m ² was applied to the sample by the weight of the measuring unit of the thickness measuring device. This thickness was defined as a reference thickness. The specific volume at this stage is the above-described reference specific volume, and was calculated from the actually measured reference thickness by the following formula.
Reference specific volume (cc / g) = π × {cylindrical radius (cm)} ² × measured reference thickness (cm) / sample mass (0.180 g)
(Iii) Next, a weight of a predetermined mass is placed on the top surface of the grip portion of the thickness measuring device so that a predetermined pressure (load) is applied to the measuring portion of the thickness measuring device. Was measured. At this time, a predetermined load was applied between the weight of the measuring unit of the thickness measuring device and the weight. This thickness was defined as the load thickness. The specific volume at this stage is the above-mentioned load specific volume, and was calculated from the actually measured load thickness by the following formula.
Load specific volume (cc / g) = π × {cylindrical radius (cm)} ² × measured load thickness (cm) / sample mass (0.180 g)

<Specific volume ratio>
Each load calculated by the above method, that is, the load specific volume at the pressure (load) was divided by the reference specific volume to calculate a specific volume ratio (dimensionless) at each load. The specific volume ratio can be said to be a value obtained by standardizing the specific volume under each load with a specific volume of a pressure (load) of 3 g / m ² .

<Change rate of specific volume ratio>
Based on the graph of the load specific volume with respect to the pressure (load) calculated by the above method, the change rate of the specific volume ratio, which is the ratio of the change of the specific volume ratio to the change of the pressure (load), was calculated. For example, in the case of the change rate of the specific volume ratio when the change of the pressure (load) is 3 g / cm ² to 5 g / cm ² , it was calculated by the following formula.
(Change rate ((g / cm ² ) ⁻¹ ))
= {(Specific volume ratio of 5 g / cm ² ) − (specific volume ratio of 3 g / cm ² )} /
{(5 g / cm ² ) − (3 g / cm ² )}

  Further, for each of the samples of Examples 1 to 4 and Comparative Example 1, the mass of the lump fiber, the number of lump fibers per unit volume, and the porosity between the core portions of the lump fiber layer were determined by the following methods.

<Mass of lump fiber>
The mass per lump of the lump fibers was calculated by measuring a predetermined number of lump fibers of, for example, 50 lump fibers with an electronic balance and dividing the mass by the number.

<Number of lump fibers per unit volume>
The number N of lumpy fibers per unit volume in the lumpy fiber layer was calculated by the following equation.
N (pieces / cm ³ ) = n (pieces) / (0.180 (g) × reference specific volume (cc / g))
Here, n (pieces) is the number of lumpy fibers put into the cylinder in the above <specific volume> (i).

<Void ratio between core parts>
The ratio of the voids between the plurality of core portions in the massive fiber layer, that is, the void ratio F1 between the core portions, was calculated by the following equation.
F1 (%) = (1- ( 4/3) × π × r 3 × N) × 100
Here, r is the radius of the core portion, and N is the number of lumpy fibers per unit volume.

  In addition, for each of the samples of Examples 1 to 4 and Comparative Example 1, the permeation time, the surface return rate and the retention rate were determined. However, the permeation time, the surface return rate and the retention rate were determined as follows.

<Evaluation method of penetration time, surface return rate and retention rate>
(I) For each of the samples of Examples 1 to 4 and Comparative Example 1 (including a topsheet, a lump fiber layer containing a plurality of lump fibers, and an absorbent core), a 10-mesh wire mesh on the bottom above the center. Was placed on the cylinder having a diameter of 60 mm.
(Ii) 15 g of artificial loose stool whose viscosity was adjusted to 2000 mPa · s was precisely weighed and injected into the cylinder with a syringe.
(Iii) A stopwatch is started at the same time as the injection of artificial soft stool is started, the time until the artificial soft stool moves to the sample through the wire mesh and the wire mesh at the bottom of the cylinder starts to be exposed is measured, and the measured time is penetrated. Time. However, if the wire mesh was not exposed even after 3 minutes, the process was terminated there.
(Iv) Three minutes after the injection of artificial soft stool, the cylinder was removed, a 10 cm × 10 cm filter paper (manufactured by AS ONE Corporation: NO1 filter paper) was placed on the sample, and a load of 20 g / cm ² was further placed on the filter paper. Was placed and allowed to stand for 30 seconds.
(V) After a lapse of 30 seconds, the mass of the filter paper was measured, the mass of the original filter paper was subtracted, and the return amount of the artificial soft stool was calculated. The value of the obtained return amount was divided by the injection amount of artificial soft stool to obtain a surface return ratio.
(Vi) Next, the topsheet was peeled off, and a massive fiber layer (including artificial soft stool) in a circular range with a diameter of 85 mm centering on the cylinder was taken out and its mass was measured.
(Vii) From the measured mass, subtract the mass (0.567 g) of the original massive fiber layer before absorbing artificial soft stool in the range of 85 mm to calculate the amount of artificial soft stool held by the massive fiber layer. did. The value of the obtained retention amount was divided by the injection amount of artificial soft stool to obtain a retention rate.

<Method of preparing artificial soft stool>
However, the method of preparing artificial soft stool is as follows.
First, an agent containing the following components in the following ratio was prepared. That is, 71.9% by mass of ion-exchanged water, 1.0% by mass of NaCl, 15.0% by mass of glycerin, 2.0% by mass of NaCMC, 0.05% by mass of Triton X-100, Red No. 102 And 0.05% by mass of powdered cellulose. Then, the viscosity of the agent was adjusted to 2000 mPa · s with ion-exchanged water to obtain artificial soft stool.

  Table 2 summarizes the results of the above-described measurements performed on the samples of Examples 1 to 4 and Comparative Example 1, the bulk fibers A to D, and the cotton balls.

11 is a graph showing the load (the relationship between pressure and specific volume) on the massive fiber layer 4b in each of the samples of Examples 1 to 4 and Comparative Example 1. The horizontal axis is the load (pressure) (g / cm ² ), the vertical axis represents the specific volume (cc / g), diamonds (◇) in Example 1, squares (□) in Example 2, triangles (△) in Example 3, and circles (〇). Is Example 4 and the inverted triangle (▽) is Comparative Example 1. In the samples of Examples 1 to 4, at the beginning of the increase in the load (pressure), the specific volume sharply decreased, but the load (pressure) decreased. With the increase of the specific volume, the specific volume decreased gradually, while the sample of Comparative Example 1 decreased at the same rate as the load (pressure) increased.

FIG. 12 is a graph showing the relationship between the load (pressure) on the massive fiber layer 4b and the specific volume ratio in each of the samples of Examples 1 to 4 and Comparative Example 1. In other words, FIG. 12 is a graph in which the value of the specific volume in the graph of FIG. 11 is normalized by the value of the specific volume of the load (pressure) of 3 g / cm ² . The horizontal axis is the load (pressure) (g / cm ² ), and the vertical axis is the specific volume ratio (dimensionless). A diamond (◇) is Example 1, a square (□) is Example 2, a triangle (△) is Example 3, a circle (〇) is Example 4, and an inverted triangle (▽) is Comparative Example 1. By the standardization, the difference between the tendency of the graphs of Examples 1 to 4 and the tendency of the graph of Comparative Example 1 became clearer.

The ratio between the change in specific volume ratio when the load (pressure) is changed from 3 g / cm ² to 5 g / cm ² and the ratio when the load (pressure) is changed from 25 g / cm ² to 30 g / cm ² The change in the volume ratio was compared. Then, as shown in Table 1, in the samples of Examples 1 to 4, −0.12 to −0.025 (g / cm ² ) ⁻¹ and −0.02 to 0 (g / cm ² ) ^{−, respectively. 1} range. On the other hand, in the sample of Comparative Example 1, they were -0.0137 and -0.0046, respectively.

  This means that in the samples of Examples 1 to 4, in the initial stage of the increase in the load (pressure), the specific volume decreases rapidly due to the contraction of the protruding fiber portion, but the increase in the load (pressure) proceeds. It is considered that when the protruding fiber portion hardly shrinks, the core portion shrinks, and the specific volume decreases gradually. On the other hand, in the sample of Comparative Example 1, since the protruding fiber portion was scarcely present, the core portion contracted from the initial stage of the increase in load (pressure), and it is considered that the core portion was reduced at a relatively same rate. That is, the effects of the protruding fiber portions of Examples 1 to 4 were confirmed.

  And, as shown in Table 1, in the samples of Examples 1 to 4, the surface return rate was 15% or less, and the retention rate was 50% or more. On the other hand, in the sample of the comparative example, the surface reversion rate exceeded 20%, and the retention rate did not reach 40%. From these, the effects of the massive fiber layer 4b of Examples 1 to 4 were confirmed. That is, the lump fiber layer 4b of Examples 1 to 4 makes it possible to suppress or exude (rewet) the high-viscosity excrement to the topsheet 2 while maintaining or improving the absorption performance for the high-viscosity excretion. became.

From the graphs in Table 1 and FIGS. 11 and 12, the rate of change of the specific volume ratio when the load (pressure) was changed from 3 g / cm ² to 5 g / cm ² was −0.12 to −0. 0.025 (g / cm ² ) ⁻¹ is preferable, and the rate of change of the specific volume ratio when the load (pressure) is changed from 25 g / cm ² to 30 g / cm ² is −0.02 to 0 ( g / cm < ² >) < ^-1 > was preferred. When the load (pressure) was 25 g / cm ² , the specific volume ratio was preferably in the range of 0.2 or more and 0.7 or less. The porosity when the load (pressure) is 3 g / cm ² is preferably 40% or more and 80% or less, and the porosity when the load (pressure) is 25 g / cm ² is 2% or more and 60% or less. The range was more favorable.

1 disposable diapers (absorbent articles)
Reference Signs List 4 absorber 4a absorbent core 40 massive fiber 4b massive fiber layer 41 core part 42 projecting fiber part

Claims (9)

A liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent article including an absorber positioned between the top sheet and the back sheet,
The absorber,
An absorbent core;
A mass fiber layer containing a plurality of mass fibers, located on the surface of the absorbent core on the top sheet side,
Each of the plurality of bulk fibers,
A core made of massive fibers, high in fiber density and hard to collapse,
Formed with crimpable fibers protruding outward from the periphery of the core portion, having a low fiber density, and a protruding fiber portion that is easily crushed,
Adjacent massive fibers are in contact with each other via the protruding fiber portion,
The specific volume of the massive fiber layer when a pressure of 3 g / cm ² is applied to the massive fiber layer is defined as a reference specific volume, and the mass when the pressure greater than 3 g / cm ² is applied to the massive fiber layer The specific volume of the fiber layer as the load specific volume, the ratio of the load specific volume to the reference specific volume as the specific volume ratio, the rate of change of the specific volume ratio to the change in pressure applied to the massive fiber layer and the rate of change When
When the change in the pressure applied to the massive fiber layer is 3 g / cm ² to 5 g / cm ² , the first change rate, which is the change rate, is −0.12 (g / cm ² ) ⁻¹ or more, and −0.025. (G / cm ² ) ^-1 or less;
When the change in the pressure applied to the massive fiber layer is 25 g / cm ² to 30 g / cm ² , the second change rate, which is the change rate, is −0.02 (g / cm ² ) ⁻¹ or more, and 0 (g / cm ² ). cm ² ) ^-1
Absorbent articles. The average thickness of the protruding fiber portion on the surface of the core portion in the massive fiber is 0.4 times or more and 2 times or less the average diameter of the core portion.
The absorbent article according to claim 1. The fibers of the core part and the fibers of the protruding fiber part in the massive fiber are the same,
The absorbent article according to claim 1. The specific volume ratio when the pressure applied to the massive fiber layer is 25 g / cm ² is 0.2 or more and 0.7 or less.
The absorbent article according to any one of claims 1 to 3. Fibers constituting each of the plurality of lump fibers are not thermally fused,
The absorbent article according to any one of claims 1 to 4. When the ratio of the voids between the cores in the massive fiber layer and the porosity,
The first porosity is 40% or more and 80% or less when the pressure applied to the massive fiber layer is 3 g / cm ² ;
The second porosity when the pressure applied to the massive fiber layer is 25 g / cm ² is 2% or more and 60% or less;
The absorbent article according to any one of claims 1 to 5. The basis weight of the adhesive between the massive fiber layer and the topsheet is lower than the basis weight of the adhesive between the massive fiber layer and the absorbent core,
The absorbent article according to any one of claims 1 to 6. At least a part of the topsheet has a plurality of through holes penetrating in the thickness direction toward the massive fiber layer,
The absorbent article according to any one of claims 1 to 7. The clumped fiber is a fiber ball,
An absorbent article according to any one of claims 1 to 8.