WO2019130751A1

WO2019130751A1 - Absorbent article

Info

Publication number: WO2019130751A1
Application number: PCT/JP2018/039070
Authority: WO
Inventors: 山口　正史; 裕樹合田
Original assignee: ユニ・チャーム株式会社
Priority date: 2017-12-26
Filing date: 2018-10-19
Publication date: 2019-07-04
Also published as: CN111386097B; JP6667495B2; TW201927268A; CN111386097A; JP2019115378A

Abstract

In order to maintain and improve the ability to absorb highly viscous excretory fluids and prevent the highly viscous excretory fluids from soaking through a surface sheet, this absorbent article (1) has an absorbent body (4) provided with an absorbent core (4a) and a fiber mass layer (4b) comprising a plurality of fiber masses (40). The fiber masses comprise: a core part (41) that has a high fiber density and is difficult to crush; and a projecting fiber part (42) that projects outward from the core part, has a low fiber density, and is easy to crush. The specific volume of the fiber mass layer when a pressure of 3 g/cm2 is applied is referred to as reference specific volume, the specific volume of the fiber mass layer when a pressure of more than 3 g/cm2 is applied is referred to as load specific volume, the ratio of the load specific volume to the reference specific volume is referred to as specific volume ratio, and the ratio of a change in the specific volume ratio to a change in the pressure applied to the fiber mass layer is referred to as change ratio. A pressure change from 3 to 5 g/cm2 corresponds to a change ratio of -0.12 to -0.025 (g/cm2)-1, and a pressure change from 25 to 30 g/cm2 corresponds to a change ratio of -0.02 to 0 (g/cm2)-1.

Description

Absorbent articles

The present invention relates to an absorbent article.

BACKGROUND ART Absorbent articles that absorb highly viscous liquid excrement are known. For example, Patent Document 1 includes a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber positioned between the top sheet and the back sheet, and the absorber is an absorbent core, Disclosed is an absorbent article comprising a porous particle layer located on the surface sheet side of the absorbent core. As the porous particles of the porous particle layer, fiber balls and porous cellulose particles are mentioned. According to Patent Document 1, the highly viscous liquid excrement excreted into the surface sheet of the absorbent article diffuses in 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 liquid excrement. As a result, the liquid waste rapidly diffuses in the porous particle layer and efficiently migrates 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 held by the porous particle layer. As a result, the movement of the liquid excrement (mainly solid component) remaining in the porous particle layer as fluid becomes dull. Thereby, when pressure is applied to the absorbent article, the exudation (rewet) of liquid excrement from the porous particle layer to the liquid-permeable surface sheet is suppressed.

JP, 2015-188709, A

Patent Document 1 describes a case where liquid excrement with high viscosity has a property of being easily separated into a solid component and a liquid component. However, high-viscosity liquid excrement may have the property that it is difficult to separate into solid components and liquid components. When high-viscosity liquid excrement (hereinafter also referred to as "high-viscosity excrement fluid") having properties that are difficult to separate into solid components and liquid components is excreted on the surface sheet of the absorbent article, Not only solid components but also liquid components can be trapped and held in the voids between the porous particles and the voids in the porous particles. When pressure is externally applied to the absorbent article holding such high-viscosity excretory fluid, the porous particles are compressed, and the volume of the void in the porous particle decreases, and the high-viscosity excrement fluid in the void is reduced. May leak to the outside of the porous particle layer. In addition, since there is nothing to prevent the movement of the voids between the porous particles, there is a possibility that the high-viscosity excretory fluid in the voids may leak to the outside of the porous particle layer. Then, the leaked high-viscosity excrement will leak to the surface sheet to cause rewet.

Therefore, an object of the present invention is to provide an absorbent article capable of suppressing the exudation (rewet) of high viscosity excrement fluid to the surface sheet while maintaining or improving the absorption performance for high viscosity excrement fluid. It is in.

The absorbent article of the present invention is an absorbent article comprising (1) a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body located between the top sheet and the back sheet. The absorbent body comprises: an absorbent core; and an aggregate fiber layer positioned on the surface sheet side of the absorbent core and including a plurality of aggregate fibers, each of the plurality of aggregate fibers being A core portion formed of massive fibers, having a high fiber density, which is not easily crushed, and a crimpable fiber which protrudes outward from the periphery of the core portion, and a protruding fiber portion which is low in fiber density and which is easily crushed; Adjacent lumped fibers are in contact with each other via the projecting fiber portion, and the specific volume of the lumped fiber layer when a pressure of 3 g / cm ² is applied to the lumped fiber layer is taken as a reference specific volume , 3 g / cm ² greater pressure is applied to the bulk fiber layer When the specific volume of the massive fiber layer is a load specific volume, the ratio of the load specific volume to the reference specific volume is a specific volume ratio, and the ratio of the change of the specific volume ratio to the change of the pressure applied to the bulk fiber layer Where the change rate of pressure applied to the massive fiber layer is 3 g / cm ² to 5 g / cm ² and the first change rate is -0.12 (g / cm ² ) ^{- A} ^second change rate which is ¹ or more and −0.025 (g / cm ² ) ⁻¹ or less, and the change rate of pressure applied to the massive fiber layer is 25 g / cm ² to 30 g / cm ² There -0.02 ^{(g /} cm ^{2) -1} or more, 0 ^{(g /} cm ²⁾ the absorbent article is less than ^-1.

In the present absorbent article, in the massive fiber layer, adjacent lumped fibers are in contact with each other via the protruding fiber part, and the fibers of the protruding fiber part repel each other while being entangled with each other to form protruding fibers between adjacent core parts. A void (a void between the core parts) is formed by the fibers of the part. At this time, since the fibers of the protruding fiber portion are made of crimped fibers and have a relatively low fiber density, they can be easily shrunk according to the pressure when a pressure (load) is applied to the massive fiber layer . Therefore, since the protruding fiber portion contracts and absorbs the pressure, the influence of the pressure on the core portion can be made difficult, 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 reduction, first, when the pressure is small, the specific volume is reduced by mainly shrinking the protruding fiber portion having a large number of voids and which tends to shrink. When the pressure is large, the specific volume is further reduced by mainly shrinking the core portion which has few voids and is hard to shrink, after the shrinkage of the projecting fiber portion proceeds sufficiently. Therefore, the decrease in the specific volume of the massive fiber layer results in stepwise contraction of the protruding fiber portion and contraction of the core portion. In this absorbent article, the first rate of change when the change in pressure applied to the bulk fiber layer from 3 g / cm ² of 5 g / cm ² is -0.12 ^{(g /} cm ^{2) -1} above, -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} Above, it is less than 0 (g / cm ² ) ⁻¹ . However, a state in which 3 g / cm ² of pressure 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 condition where the force is applied simulates the condition where a large pressure is applied to the absorbent article as if the wearer is in the sitting position. And, a change in pressure (load) from 3 g / cm ² to 5 g / cm ² corresponds to a change in shrinkage of the protruding fiber part, and a change in pressure (load) from 25 g / cm ² to 30 g / cm ² causes a change in contraction of the core part Corresponds to
When such an absorbent article absorbs high-viscosity liquid excrement having a property of being difficult to separate into a solid component and a liquid component, ie, high-viscosity excrement fluid, voids in the core portion of the massive fiber in the massive fiber layer and The high viscosity excretory fluid can be supplemented and held in the void in the projecting fiber portion. At this time, since the core portion having the highest fiber density in the massive fiber layer has a high fiber density, the high-viscosity excretory fluid temporarily retained in the protruding fiber portion is a portion adjacent to the protruding fiber portion when there is ample capacity. Absorb from and hold. And when such an absorbent article is applied pressure due to a change in the posture of the wearer or the like while holding high-viscosity excretory fluid, the crimped fibers of the protruding fiber portion according to the pressure It can absorb the pressure by shrinking and becoming a cushion. Therefore, the pressure can be hardly applied to the core portion. As a result, it is possible to make it difficult for the high-viscosity excrement fluid held in the void in the core portion to be pushed out. Furthermore, the distance between the massive fibers is reduced, and the fiber density of the voids of the projecting fiber portion is increased, that is, the fiber density around the core portion is increased, so that the leakage from the core portion can be suppressed. Here, when a large amount of high-viscosity waste fluid is held in the voids of the protruding fiber portion, the high-viscosity waste fluid held in the voids of the protruding fiber portion is contracted by the contraction of the protruding fiber portion. It can also be thought that it becomes easy to be pushed out. However, since the high-viscosity excrement fluid is moving downward (absorber side) of the protruding fiber portion by its own weight, it is covered by the protruding fiber portion above (surface sheet side), ie, upward It is in the state of being covered. As a result, even if the gap of the protruding fiber portion shrinks, the upper protruding fiber portion (lid) can suppress leakage of the high-viscosity excrement fluid to the surface sheet side. In addition, the high viscosity excretory fluid which has gone out of place goes through the protruding fiber part of the lumped fiber in the middle of the lumped fiber core part or protruding fiber part of the non-loaded part (for example: crevice of the buttocks). It can move. As a result, it is difficult to push it out. By such an absorbent article, it is possible to further suppress the exudation of liquid excrement to the surface sheet while maintaining or improving the absorption performance for high viscosity excretory fluid. In addition, with respect to liquid excrement having a property of being easily separated into a solid component and a liquid component, the solid component may be mainly absorbed by the massive fiber layer, and the liquid component may be mainly absorbed by the absorbent core.

However, if the first rate of change is less than -0.12 (g / cm ² ) ^-1 , that is, it exceeds 0.12 in absolute value, the specific volume ratio due to the shrinkage of the projecting fiber portion to the change in pressure applied to the massive fiber layer Is too large (for example, there are many voids in the projecting fiber portion or a small amount of fibers in the projecting fiber portion), so that the retained high-viscosity excretory fluid is likely to be released. On the other hand, when the first change rate is more than -0.025 (g / cm ² ) ^-1 , that is, less than 0.025 in absolute value, the specific volume due to the contraction of the protruding fiber part with respect to the change in pressure applied to the massive fiber layer Since the decrease in the ratio is too small (eg, the number of voids in the projecting fiber portion or the amount of fibers in the projecting fiber portion is large), it becomes difficult to sufficiently retain the high-viscosity excretory fluid. In addition, when the second change rate is less than -0.02 (g / cm ² ) ^-1 , that is, when it exceeds 0.015 in absolute value, the specific volume ratio of the core portion due to the change in pressure applied to the massive fiber layer is Since the decrease is too large (the number of voids in the core is large, or the amount of fibers in the core is small, etc.), the core is likely to be deformed and the high-viscosity waste fluid is likely to exude.

In the absorbent article of the present invention, (2) the average thickness of the projecting 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 And the absorbent article as described in (1) above.
In the 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 projecting fiber portion is in this range, the high viscosity excretory fluid can be appropriately held in the void of the projecting fiber portion, and when pressure is applied to the massive fiber layer, the void of the projecting fiber portion is It can be suitably compressed into a cushion that can absorb its pressure properly, thereby providing less pressure to the core. At this time, when the average thickness of the protruding fiber portion is less than 0.4 times the average diameter of the core portion, the gap of the protruding fiber portion can not be sufficiently secured, and pressure is easily applied to the core portion. It becomes easy for the high viscosity waste fluid 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 in a state where a large amount of high-viscosity excrement is held in the protruding fiber portion, and the protruding fiber It becomes easy for the high viscosity waste fluid to exude from the part.

The absorbent article of the present invention is (3) the absorbent article according to the above (1) or (2), wherein the fibers of the core portion and the fibers of the protruding fiber portion in the massive fibers are the same. May be
In the present absorbent article, the fibers of the core portion and the fibers of the protruding fiber portion are the same. Therefore, since the fibers are continuously connected from the core portion to the protruding fiber portion, the high viscosity excretory fluid can be supplemented by the protruding fiber portion and can be more easily introduced to the core portion. At the same time, since the predetermined projecting fiber portion and the core portion can be more accurately formed, the core portion having a high fiber density can be more reliably prevented from collapsing, and the projecting fiber portion having a low fiber density can be easily collapsed. can do. Thereby, when pressure is applied to the massive fiber layer, the gaps of the projecting fiber portions are appropriately shrunk to form a cushion, and the pressure can be appropriately absorbed, thereby preventing more pressure from being applied to the core portion. be able to.

In the absorbent article of the present invention, 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. It may be the absorbent article according to any one of 3).
In the present absorbent article, the specific volume ratio at 25 g / cm ² pressure is 0.2 to 0.7. When the specific volume ratio is in this range, the voids of the projecting fiber portion can be appropriately shrunk when pressure is applied to the massive fiber layer. Therefore, in the protruding fiber part, the fiber density becomes high, and it is suppressed that the high viscosity excretory fluid in the void of the protruding fiber part exudes to the outside. In addition, in the core portion, the protruding fiber portion acts as a cushion and absorbs pressure appropriately, so that pressure is hardly applied to the core portion, and it is suppressed that the high viscosity excretory fluid in the void of the core portion leaks to the outside . At this time, when 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 excretory fluid is likely to ooze out 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 excretory fluid is likely to ooze 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 massive fibers are not heat-sealed together. , May be.
In the present absorbent article, since the fibers of the massive fibers are not heat-sealed together, when pressure is applied to the absorbent article, the fibers of the projecting fiber portion can be easily shrunk, and the pressure is increased in the core portion It is possible not to join. Moreover, when the space | gap of a protrusion fiber part and the space | gap between core parts expand | swell by absorbing a highly viscous waste fluid, it can suppress that the intersection of fibers prevents 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 core portions in the massive fiber layer is a porosity. (1) to (5), wherein the second porosity is 2% to 60% when the pressure is 40% to 80% and 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 absorbent article, the first porosity of the massive fiber layer is 40% to 80%, and the second porosity is 2% to 60%. Since the void ratio of 40% to 80% (3 g / cm ² ) when little pressure is applied to the massive fiber layer, the pressure is buffered while securing a core portion sufficient for capturing high-viscosity excretory fluid It is possible to secure a protruding fiber portion that is sufficient to In addition, since the porosity of the massive fiber layer (25 g / cm ² ) is 2% to 60% when pressure is applied (25 g / cm ² ), the protruding fiber portion is secured while securing a protruding fiber portion sufficient to retain high viscosity excretory fluid. The fiber portion can be sufficiently shrunk to suppress the application of pressure to the core portion. Here, when the porosity at 3 g / cm ² pressure of the massive fiber layer is less than 40%, a void capable of shrinking appropriately when the pressure is increased can not be secured in the projecting fiber portion, In this case, it is not possible to secure a void capable of sufficiently absorbing high-viscosity waste fluid in the core portion. In addition, when the porosity at 25 g / cm ² pressure of the massive fiber layer is less than 2%, a void capable of sufficiently retaining high-viscosity excretory fluid can not be secured in the projecting fiber portion, and is more than 60%, It becomes difficult to hold the high viscosity excretory fluid in the void of the protruding fiber part.

In the absorbent article of the present invention, (7) the basis weight of the adhesive between the bulk fiber layer and the surface sheet is higher than the basis weight of the adhesive between the bulk fiber layer and the absorbent core The absorbent article according to any one of the above (1) to (6) may be low.
In the absorbent article, the basis weight of the adhesive between the aggregate fiber layer and the surface sheet (example: hot melt adhesive) is lower than the basis weight of the adhesive between the aggregate fiber layer and the absorbent core. Therefore, the situation in which the space of the massive fiber layer can not be used for absorption and migration of high-viscosity waste fluid by the adhesive can be suppressed. As a result, the massive fiber layer can quickly capture and retain the high-viscosity waste fluid. In addition, since the basis weight of the adhesive between the absorbent core and the massive fiber layer is relatively large, the contact area with the absorbent core is increased, and the moisture of the highly viscous excretable fluid is increased in the absorbent core having high hydrophilicity. Easy to migrate.

In the absorbent article of the present invention, any one of the above (1) to (7), wherein (8) at least a part of the surface sheet 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.
In the present absorbent article, since the surface sheet does not prevent the permeation of the high viscosity excretory fluid, the high viscosity excretory fluid can be more rapidly transferred to the massive fiber layer. However, the plurality of through holes are not only the through holes formed as the holes, but also the gaps between the fibers of the sheet as if the through holes are open and the basis weight of the top sheet is small.

The absorbent article of the present invention may be (9) the absorbent article according to any one of the above (1) to (8), which is a fiber ball.
In the present absorbent article, since the massive fibers are formed of fiber balls, it is possible to easily form a massive fiber and a massive fiber layer having predetermined core portions and projecting fiber portions.

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

It is a perspective view showing an example of composition of a disposable diaper concerning an embodiment. It is a top view which shows the state which expand | deployed the disposable diaper of FIG. It is a disassembled perspective view of the disposable diaper of FIG. It is a figure which shows the structural example of the absorber of the disposable diaper of FIG. It is a schematic diagram which shows the structural example of the lump fiber of the absorber of FIG. 4, and a lump fiber layer. It is a schematic diagram which shows the structural example of the manufacturing apparatus of the absorber which concerns on embodiment. It is a figure which shows the other structural example of the absorber of the disposable diaper of FIG. It is a figure which shows the further another structural example of the absorber of the disposable diaper of FIG. It is a figure which shows the further another structural example of the absorber of the disposable diaper of FIG. It is an optical micrograph and a binarized process image of the massive fiber of an absorber. It is a graph which shows the load in a massive fiber layer, and the relation of 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 regard 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 is applicable to various absorbent articles without departing from the scope of the subject matter of the present invention. As such an absorbent article, a tape type disposable diaper, a urine absorption pad, a stool pad, a sanitary napkin, etc. are mentioned, for example.

First, the disposable diaper 1 according to the present embodiment will be described.
1 to 3 are diagrams showing an example of the configuration of the disposable diaper 1 according to the present embodiment. However, FIG. 1 is a perspective view which shows the state when using the disposable diaper 1, FIG. 2 is a top view which shows the state which expanded the disposable diaper 1, FIG. 3 shows the state which disassembled the disposable diaper 1. It is a perspective view. The disposable diaper 1 has a longitudinal direction L orthogonal to one another, a width direction W, and a thickness direction T in the state shown in FIGS. 2 and 3 and extends in the longitudinal direction L through the center of the width direction W A direction center line CL and a width direction center line CW which passes through the center of the longitudinal direction L and extends in the width direction W are provided. Further, the direction toward and away from the longitudinal center line CL is taken as the inward direction and the outward direction of the width direction W, respectively. The direction toward and away from the widthwise center line CW is taken as the inward direction and the outward 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 the upper side in the thickness direction T is referred to as "plan view", and the shape grasped in plan view is referred to as "plane shape". . The “skin side” and the “non-skin side” mean the side closer to the skin surface of the wearer and the side farther from the skin surface in the thickness direction T of the disposable diaper 1 when the disposable diaper 1 is mounted. These directions and the like are similarly applied to the respective materials constituting the disposable diaper 1.

The disposable diaper 1 comprises a ventral side 11, a dorsal side 13, and an intermediate portion 12 between the ventral side 11 and the dorsal side 13. The ventral side 11 is a portion of the disposable diaper 1 that is applied to the abdomen of the wearer. The middle portion 12 is a portion applied to the crotch portion of the wearer of the disposable diaper 1. The back side 13 is a portion of the disposable diaper 1 that is applied to the buttocks and / or the back of the wearer. A pair of both ends 11a and 11b in the width direction W of the ventral side 11 and both

ends

13a and 13b in the width direction W of the back side 13 overlap in the thickness direction T along the longitudinal direction L, respectively. Are joined together at the

joint portions

14a and 14b. In the disposable diaper 1, an end 11 e opposite to the middle portion 12 in the longitudinal direction L in the abdominal side 11 and an end 13 e opposite to the middle portion 12 in the longitudinal direction L in the back side 13 Thus, the waist opening WO is formed. Further, in the disposable diaper 1, a pair of leg openings LO, LO is formed by the

side portions

12 a, 12 b in the width direction W of the intermediate portion 12.

The disposable diaper 1 includes an absorbent main body 10 for absorbing and holding excrement, and a cover sheet 3 and a cover sheet 6 for holding the absorbent main body 10 from the non-skin side and the skin side. The cover sheet 3 and the cover sheet cover both sides in the thickness direction T of the absorbent main body 10 and extend around the width direction W and the longitudinal direction L of the absorbent main body 10. In the cover sheet 6 on the skin side, in order to expose the skin-side surface of the absorbent main body 10, a substantially rounded rectangular (or oval, oval) at substantially the center in the width direction W and the longitudinal direction L An opening 6a is provided to facilitate absorption of excrement. The absorbent main body 10 is positioned between the top sheet 2 having liquid permeability, the back sheet 8 having liquid impermeability, and between the top sheet 2 and the back sheet 8, and has liquid absorbability and liquid retention. And an absorber 4 are included. The absorbent body 4 has a configuration in which an absorbent core 4 a located on the non-skin side and a massive fiber layer 4 b located on the skin side are stacked in the thickness direction T.

As materials of the top sheet 2, the back sheet 8, the absorbent core 4 a of the absorber 4, the cover sheet 3 and the cover sheet 6, known materials which can be generally used in the disposable diaper 1 can be used. That is, as a material of the surface sheet 2, for example, a liquid-permeable nonwoven fabric, a synthetic resin film in which a hole for liquid permeation is formed, a composite sheet of these, and the like can be mentioned. Examples of non-woven materials include natural fibers, regenerated fibers, inorganic fibers, synthetic resin fibers and the like. The basis weight of the surface sheet 2, for example, 2 ~ 100 g / ^{m 2} can be mentioned, preferably 5 ~ 50 g / ^{m 2} from the viewpoint of facilitating the transmission of high-viscosity liquid waste, and more preferably 8 ~ 20g / ^{m 2.} Examples of the back sheet 8 include liquid impermeable non-woven fabrics, synthetic resin films, composite sheets thereof, and SMS non-woven fabrics. Examples of the material of the absorbent core 4a of the absorbent 4 include hydrophilic fibers such as pulp fibers and synthetic fibers, and superabsorbent 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 a material of the cover sheet 3, for example, the same material as that of the top sheet 2 can be used. As a 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 and the cover sheet 3 and the cover sheet 6 are respectively bonded with an adhesive, and the absorbent body 4 and the top sheet 2 and the back sheet 8 are each bonded with an adhesive. The adhesive can be a known material, such as a hot melt adhesive.

The disposable diaper 1 may be provided with a pair of liquid impermeable

leakproof walls

7a and 7b, and an elastic body 9 (9a, 9b, 9c, 9d). The pair of

leak preventing walls

7 a and 7 b extend along the longitudinal direction L on both sides in the width direction W on the skin-side surface of the surface sheet 2 and are disposed apart from each other in the width direction W. In each of the pair of

leak preventing walls

7a and 7b, a portion on the outer side in the width direction W is fixed to the surface sheet 2 by heat welding or the like to be a fixed end, and an inner end portion in the width direction W can stretch. It is considered as a free end to form In the vicinity of the free end of each of the pair of

leak preventing walls

7a and 7b, a plurality of elastic bodies 7Ea and 7Eb such as thread rubber extending along the longitudinal direction L are arranged. 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 in the ventral side 11 and the back side 13, respectively, and are spaced apart in the longitudinal direction L, and are narrow Will be held. The

elastic bodies

9a and 9b expand and contract the waist opening WO. The

elastic bodies

9c and 9d are generally along the longitudinal direction L at both ends in the width direction W of the portion on the ventral side 11 and the back side 13 in the middle portion 12, and the width in the middle portion of the middle portion 12 It is arranged continuously along the direction W. The

elastic bodies

9c and 9d extend and contract the pair of leg openings LO and LO, respectively. The elastic body 9 is, for example, a rubber thread.

Next, the absorber 4 will be further described. FIG. 4 is a view showing a configuration example of the absorbent body 4 of the disposable diaper 1. 4 (a) is a plan view of the absorber 4, and FIG. 4 (b) is a cross-sectional view of the absorber 4 taken along the line IVb-IVb. As described above, in the absorbent body 4, the absorbent core 4 a located on the non-skin side (the back sheet 8 side) and the massive fiber layer 4 b located on the skin side (the top sheet 2 side) have a thickness direction T Have a stacked structure. In the present embodiment, the massive fiber layer 4 b covers the entire surface of the absorbent core 4 a on the surface sheet 2 side. The absorbent core 4a has liquid absorbency and liquid holdability, and mainly absorbs and retains liquid excrement such as urine. The massive fiber layer 4b absorbs and holds excrement containing solid components such as soft stools and liquid components. However, 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 encloses the absorbent core body 4a-1. An example of the material of the core wrap 4a-2 is a tissue.

Here, when the porous particle layer of Patent Document 1 is used as the massive fiber layer 4b, although it is effective for absorption and retention of liquid excrement which is easily separated into solid component and liquid component, solid component and liquid component It is not necessarily effective for high-viscosity liquid excrement that is difficult to separate into, ie, high-viscosity excretory fluid. The reason is that when the porous particle layer absorbs high-viscosity waste liquid, it absorbs and holds not only solid components but also liquid components, so when external pressure is applied to the porous particle layer in that state, the internal high viscosity It is because there is a possibility that the excrement fluid may leak to the outside. Then, the leaked high-viscosity excrement will leak to the surface sheet to cause rewet.
So, in disposable diaper 1 of this embodiment, a layer containing a plurality of block fibers which have a predetermined composition is used as block fiber layer 4b of absorber 4. Such a massive fiber layer 4b can absorb and retain high viscosity excretory fluid appropriately, and can appropriately suppress the leakage of internal high viscosity excretory fluid to the outside even if pressure is applied from the outside. The high-viscosity excrement includes, for example, soft stools of a baby before baby food. The details will be described below.

FIG. 5: is a schematic diagram which shows the structural example of the massive fiber layer 4b of FIG. 4, and several massive fibers 40. As shown in FIG. Fig. 5 (a) shows a configuration example of the massive fiber 40, and Fig. 5 (b) shows a configuration example of the massive fiber layer 4b. The massive fiber layer 4 b contains a plurality of massive fibers 40. As shown in FIG. 5 (a), the massive fiber 40 is formed of massive fibers in a state like a lump of three-dimensional shape as a whole while a plurality of fibers are intertwined, and the core is high in fiber density and hard to crush. A portion 41 and crimped fibers protruding outward from the peripheral edge of the core portion 41 are included, and the fiber density is low, and includes a collapsible protruding fiber portion 42. And as shown in FIG.5 (b), in the block fiber layer 4b, adjacent block fibers 40 are in contact via the protrusion fiber part 42 of each other.

The disposable diaper 1 provided with the massive fiber layer 4b can exhibit the following effects.
In the massive fiber layer 4b, adjacent massive fibers 40 are in contact with each other through the projecting fiber portion 42, and the fibers of the projecting fiber portion 42 repel each other while being entangled with each other, so that projecting fiber portions are formed between the adjacent core portions 41. An air gap (air space between core portions 41) of 42 fibers is formed. At this time, since the fibers of the projecting fiber portion 42 are made of crimped fibers and have a relatively low fiber density, when pressure (load) is applied to the massive fiber layer 4b, it is easily made according to the pressure It can contract. Therefore, since the protruding fiber portion 42 contracts and absorbs the pressure, the influence of the pressure on the core portion 41 can be made difficult, 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 reduction, first, when the pressure is small, the fiber density is low, and since the number of voids is large, the specific volume is reduced by mainly shrinking the protruding fiber portion 42 which easily shrinks. When the pressure is large, the shrinkage of the protruding fiber portion 42 sufficiently proceeds, and the core portion 41 having a small gap and a hard to shrink is mainly shrunk to further reduce the specific volume. Therefore, with the decrease of the specific volume of the massive fiber layer 4b, the contraction of the protruding fiber portion 42 and the contraction of the core portion 41 proceed substantially in stages.

And when such a disposable diaper 1 absorbs the high-viscosity excrement fluid which has a property which is hard to be separated into a solid ingredient and a liquid ingredient, a void and a projecting fiber in core part 41 of massive fiber 40 in massive fiber layer 4b The void in the portion 42 can be supplemented with high viscosity waste fluid and held. At this time, since the core portion 41 having the highest fiber density in the massive fiber layer 4b has a high fiber density, the high viscosity excretory fluid temporarily held by the protruding fiber portion 42 is used as the protruding fiber portion 42 when the capacity is sufficient. It can be absorbed from the part adjacent to and held.
Furthermore, when pressure is applied due to a change in the posture of the wearer or the like in the state where the disposable diaper 1 holds the high-viscosity excretory fluid, the crimped fibers of the protruding fiber portion 42 according to the pressure. It can absorb the pressure by shrinking and becoming a cushion. Therefore, the pressure can be hardly applied to the core portion 41. As a result, it is possible to make it difficult for the high viscosity excretory fluid held in the space in the core portion 41 to be pushed out. Furthermore, the distance between the massive fibers 40 is reduced, and the fiber density of the voids of the protruding fiber portion 42 is increased, that is, the fiber density around the core portion 41 is increased, thereby suppressing leakage from the core portion 41. Can. As a result, the surface reversion rate, which is the rate at which the high-viscosity excretory fluid that has been absorbed once, returns to the top sheet 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 high viscosity excrement fluid is held in the voids of the protruding fiber portion 42, the high viscosity excretory fluid held in the voids of the protruding fiber portion 42 by the contraction of the protruding fiber portion 42. It can be thought that it becomes easy to be pushed out outside. However, since the high-viscosity excrement fluid is moved downward (by the absorbent core 4 a) of the protruding fiber portion 42 by its own weight, it is in a state of being covered by the protruding fiber portion 42 above (the top sheet 2 side). That is, in a state of being covered upward. As a result, even if the gap of the projecting fiber portion 42 is contracted, the lid (the projecting fiber portion 42 at the upper side) can suppress leakage of the high-viscosity excretory fluid to the surface sheet 2 side. In addition, the high viscosity excretory fluid which has not gone is a protrusion fiber of the massive fiber 40 in the middle of the void 41 of the core portion 41 or the projecting fiber portion 42 of the massive fiber 40 in a portion not loaded (for example: split of the buttocks). It can move through the section 42. As a result, it is difficult to push it out. In addition, with respect to liquid excrement having a property of being easily separated into a solid component and a liquid component, the solid component may be mainly absorbed by the massive fiber layer, and the liquid component may be mainly absorbed by the absorbent core. In addition, with respect to liquid excrement having a property of being easily separated into a solid component and a liquid component, the solid component may be mainly absorbed by the massive fiber layer, and the liquid component may be mainly absorbed by the absorbent core.

With such a disposable diaper 1, it is possible to further suppress the exudation of the high viscosity excretory fluid to the surface sheet 2 while maintaining or improving the absorption performance for the high viscosity excretory fluid.

However, it can be confirmed, for example, by the following method that the fiber density of the core portion 41 is relatively high and the fiber density of the projecting fiber portion 42 is relatively low. That is, a 360-degree scan of a massive fiber or massive fiber layer is performed using a fluoroscope FLEX-M863. Specifically, an X-ray fluoroscopic image is taken every time the sample is rotated 0.2 degrees, 360 degrees, ie, 1800 X-ray fluoroscopic images are acquired, and the acquired 1800 X-ray fluoroscopic images are connected. Create a 3D image together. And the area | region of the same volume of the core part 41 and the protrusion fiber part 42 was extracted from 3D image, respectively, the number of approximate fibers was measured from each area | region extracted, and it compared.

Here, it is important that the massive fiber layer 4b have the following configuration.
The specific volume of the massive fiber layer 4 b when a pressure (load) of 3 g / cm ² is applied to the massive fiber layer 4 b is taken as a reference specific volume (unit: cc / g). Further, 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 taken as the load specific volume (unit: cc / g). Further, the ratio of the load specific volume to the reference specific volume is defined as a specific volume ratio (unit: dimensionless). And let the rate of change of the specific volume ratio to the change of the pressure applied to the massive fiber layer 4b be the rate of change (unit: (g / cm ² ) ^-1 ). At that time, the massive fiber layer 4b of the disposable diaper 1 having the above-described effects and advantages has the following configuration. The first rate of change, which is the rate of change when the change in pressure (load) applied to the massive fiber layer 4b is 3 g / cm ² to 5 g / cm ² , is -0.12 (g / cm ² ) ^-1 or more, -0 .025 (g / cm ² ) ^-1 or less. Preferably, the first change rate is -0.10 (g / cm ² ) ^-1 or more and -0.030 (g / cm ² ) ^-1 . And, the second change rate, which is the change rate when the change in pressure (load) applied to the massive fiber layer 4 b is 25 g / cm ² to 30 g / cm ² , is −0.02 (g / cm ² ) ⁻¹ or more, It is less than 0 (g / cm ² ) ⁻¹ . Preferably, the second change rate is -0.01 (g / cm ² ) ^-1 or more and -0.005 (g / cm ² ) ^-1 or less. Here, a state in which 3 g / cm ² of pressure is applied to the massive fiber layer 4 b simulates a state in which almost no pressure is applied to the disposable diaper 1 where the wearer is standing, and 25 g / cm to the massive fiber layer 4 b. ^The state in which the pressure of 2 is applied simulates the state of applying a large pressure to the disposable diaper 1 in which the wearer is in the sitting position. And, a change in pressure (load) from 3 g / cm ² to 5 g / cm ² corresponds to a change in contraction of the projecting fiber portion 42, and a change in pressure (load) from 25 g / cm ² to 30 g / cm ² Respond to contraction changes.

When the first change rate is less than -0.12 (g / cm ² ) ^-1 , the decrease in the specific volume ratio due to the contraction of the projecting fiber portion 42 with respect to the change in the pressure applied to the massive fiber layer 4 b is too large (protrusion Because the number of voids in the fiber portion 42 is large, the amount of fibers in the protruding fiber portion 42 is small, etc.), the retained high viscosity excretory fluid can be easily released. On the other hand, when the first change rate exceeds -0.025 (g / cm ² ) ^-1 , the decrease of the specific volume ratio due to the contraction of the projecting fiber portion 42 to the change of the pressure applied to the massive fiber layer 4b is too small (protrusion Because the number of voids in the fiber portion 42 is small, or the amount of fibers in the protruding fiber portion 42 is large, etc.), it is difficult to sufficiently retain the high-viscosity waste fluid. In addition, when the second change rate is less than -0.02 (g / cm ² ) ^-1 , that is, when it exceeds 0.015 in absolute value, the specific volume due to the shrinkage of the core portion 41 with respect to the change in pressure applied to the massive fiber layer 4b Since the ratio decrease is too large (more voids in the core portion 41, less fibers in the core portion 41, etc.), the core portion 41 is easily deformed and the high-viscosity waste fluid is likely to exude.

The specific volume of the massive fiber layer 4b is appropriately set according to the required absorption amount of the high viscosity excretory fluid. In the present embodiment, when the pressure (load) applied to the massive fiber layer 4 b is 3 g / cm ² , the specific volume of the massive fiber layer 4 b is, for example, 50 to 90 cc / g, and the pressure (load) is 25 g / cm. 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 becomes relatively high, and the amount of absorption of high viscosity excrement fluid becomes relatively small. Tend to be difficult to release.

The sizes of the core portion 41 and the massive fibers 40 are appropriately set depending on the required absorption amount of the high viscosity excretory fluid and the like. In the present embodiment, the shapes of the core portion 41 and the massive fibers 40 are massive and not spherical, and the shapes of the projecting fiber portions 42 covering the outer peripheral surface of the core portion 41 are also not uniform in thickness. Therefore, in the present embodiment, the core portion 41 and the massive fibers 40 are regarded as a sphere, and the protruding fiber portion 42 is regarded as a layer of uniform thickness covering the outer peripheral surface of the core portion 41. At that 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 range of 0.2 to 1 cm as the diameter 2r). The average thickness d of the protruding fiber portion 42 may be, for example, in the range of 0.2 to 0.6 cm. Therefore, the average radius (r + d) of the massive fibers 40 is, for example, in the range of 0.3 to 1.1 cm (for example, the range of 0.6 to 2.2 as the diameter 2 × (r + d)). However, when the diameter of the core portion 41 is relatively large, the amount of absorption of the highly viscous excretory fluid that can be stably held increases relatively, but tends to be easily influenced by the body pressure of the wearer. When the thickness of the protruding fiber portion 42 is relatively large, the amount of absorption of the highly viscous excretory fluid that can be stably held is relatively small, but it tends to be less susceptible to the body pressure of the wearer.

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. A range of 5 is more preferable. That is, the average thickness d of the protruding fiber portions 42 on the surface of the core portion 41 in the massive fiber 40 is preferably 0.4 times or more and 2 times or less the average diameter 2r of the core portion 41, and 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 excretory fluid can be more appropriately held in the void of the protruding fiber portion 42, and pressure is applied to the massive fiber layer 4b. When this occurs, the gaps of the projecting fiber portions 42 contract more appropriately, and the pressure can be absorbed more appropriately. Thereby, 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 less than 0.4 times the average diameter 2r of the core portion 41, the gap of the protruding fiber portion 42 can not be sufficiently secured, and pressure is applied to the core portion 41. As a result, the high-viscosity excretory fluid is easily exuded 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 shrinks in a state in which a large amount of high viscosity excrement fluid is held by the protruding fiber portion 42 As a result, the high-viscosity waste fluid is likely to exude from the protruding fiber portion 42.

The mass per one mass fiber 40 and the number of the mass fibers 40 per 1 cm ^{3 of the} mass fiber layer 4 b are appropriately set according to the required absorption amount of the high viscosity excretory fluid and the like. In the present embodiment, the mass per one mass fiber is, for example, 0.5 to 8 mg / piece. The number of bulk fibers 40 per 1 cm ^{3 of the} bulk fiber layer 4 b (with no load) may be, for example, 2.5 to 30 / cm ³ . However, when the mass per one mass fiber 40 and the number of the mass fibers 40 per 1 cm ^{3 of the} mass fiber layer 4 b are relatively large, the absorption amount of the high viscosity excretory fluid becomes relatively large.

In a preferable mode in the present embodiment, the specific volume ratio at a pressure of 25 g / cm ² applied to the massive fiber layer 4 b is 0.2 or more and 0.7 or less, and 0.3 or more and 0.6 or less. More preferable.
When the specific volume ratio at 25 g / cm ² pressure is in this range, when pressure is applied to the massive fiber layer 4 b, the voids of the projecting fiber portion 42 can be more appropriately shrunk. As a result, in the projecting fiber portion 42, the fiber density of the projecting fiber portion 42 becomes sufficiently high, and it is possible to further suppress the high viscosity excretory fluid in the void of the projecting fiber portion 42 from leaking out. Further, in the core portion 41, the protruding fiber portion 42 acts as a cushion and absorbs pressure more appropriately, so that pressure is less likely to be applied to the core portion 41, and high viscosity excretory fluid in the void of the core portion 41 stains to the outside. It is possible to further suppress the release. Here, when the ratio of the load specific volume is less than 0.2, the contraction of the protruding fiber portion 42 due to pressure is too large, and the high-viscosity excretory fluid is likely to ooze out mainly 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, and the high-viscosity excretory fluid is likely to ooze out mainly from the core portion 41.

Assuming that the ratio of voids between the core portions 41 in the massive fiber layer 4b is the porosity, the void ratio when the pressure applied to the massive fiber layer 4b is 3 g / cm ² is taken as the first void ratio, and The porosity when the applied pressure is 25 g / cm ² is taken as the second porosity. At that 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, the porosity of 40% to 80% when little pressure is applied to the massive fiber layer 4b (3 g / cm ² ), the high viscosity excretory fluid is supplemented The protruding fiber portion 42 sufficient to buffer pressure can be secured while securing the core portion 41 sufficiently. Also, when the second porosity is in this range, that is, the porosity of 2% to 60% when the pressure is applied to the massive fiber layer 4b (25 g / cm ² ), the high viscosity excretory fluid is retained. The protruding fiber portion 42 can be sufficiently shrunk and the application of pressure to the core portion 41 can be suppressed while securing the protruding fiber portion 42 sufficiently. When the first porosity is less than 40%, voids capable of shrinking appropriately can not be secured in the projecting fiber portion 42 when the pressure is increased, and when it is more than 80%, voids capable of sufficiently absorbing high-viscosity excretory fluid Can not be secured in the core portion 41. In addition, when the first porosity is less than 5%, a void capable of sufficiently retaining the high-viscosity excrement fluid can not be secured in the projecting fiber portion 42, and when it exceeds 60%, the high-viscosity excrement fluid is projected It becomes difficult to hold in the void of the part 42.

As another embodiment, at least a part of the surface sheet 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 top sheet 2 to the other surface, and function as holes capable of transmitting not only liquid components but also solid components. Therefore, the highly viscous waste fluid can permeate the surface sheet 2 through the plurality of through holes. As for the plurality of through holes, the ratio of the sum of the cross-sectional areas of the through holes to the area of the top sheet 2, that is, the hole area ratio is preferably 5 to 90%. The hole diameter of the through holes is preferably smaller than the diameter of the massive fibers 40 contained in the massive fiber layer 4b, the upper limit is preferably less than 1 cm, and the lower limit is not particularly limited, and for example, 0.08 cm or more can be mentioned. The number of through holes is preferably 0.3 to 30 per cm ² . Since the surface sheet 2 has a large number of voids when the basis weight is low (example: 8 to 20 g / m ² ), it can be referred to as the surface sheet 2 having a plurality of through holes.

The massive fibers 40 contained in the massive fiber layer 4 b are preferably composed of fibers having hydrophilicity. Thereby, hydrophilic property can be given to the massive fiber layer 4b. Examples of hydrophilic fibers include at least one of hydrophilic fibers and hydrophilized hydrophobic fibers. Hydrophilic fibers include, for example, fibers made of hydrophilic materials such as cotton and pulp, hydrophobic fibers include, for example, polyester fibers and polyolefin fibers, etc. Hydrophilization treatment is, for example, treatment using a surfactant, a hydrophilic agent, etc. Can be mentioned. The massive fibers 40 may include hydrophobic fibers within the range in which the hydrophilicity can be maintained. Since the massive fiber layer 4 b is hydrophilic, excrement can be efficiently transmitted, absorbed, and held. In a preferred embodiment of the present embodiment, the massive fibers 40 are fiber balls. Fiber balls are clumps of fibers that are relatively spherical in appearance. By forming the massive fibers 40 by fiber balls, it is possible to easily form the massive fibers 40 and the massive fiber layer 4 b having the predetermined core portion 41 and the protruding fiber portions 42.

When using a fiber ball as the massive fiber 40, one produced using a conventionally known method may be used, or a commercially available product may be used. As a method of producing the fiber ball, for example, a method of entangling fibers and granulating (example: JP-A-2016-94692), a method of thermally fusing or shrinking fibers and granulating (example: JP-A-2000) JP-345457, JP-A-7-39659, etc.) and methods of granulation using a binder (example: JP-A-63-50373, JP-A-11-105030). For example, JP-A-2016-94692 discloses that heat-weldable fibers and / or fibers which are not heat-weldable or not heat-weldable are rotated in a frusto-conical container in which air flows by rotating air. A method of three-dimensionally rotating and rolling to form a fiber ball is disclosed. Further, in JP-A-2000-345457, a heat-adhesive composite fiber comprising a thermoplastic elastomer as a heat-adhesive component, a polyester-based main fiber having high dry heat shrinkage, and a fiber ball while heat-shrinking the main fiber There is disclosed a manufacturing method of forming into. Further, in JP-A-7-39659, a plurality of synthetic fiber crimped yarns are aligned, converged, 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 developing a crimp of processed yarn. In each of these methods, for example, by controlling molding conditions and heat treatment conditions, a massive fiber 40 which is a fiber ball having the core portion 41 and the projecting fiber portion 42 can be formed.

A commercially available fiber ball manufacturing apparatus (example: Ball Fibers Forming Machine CMM1 manufactured by Masias Co., Ltd.) can be used to manufacture the fiber balls. Examples of the fiber ball manufactured by the fiber ball manufacturing apparatus include fiber balls obtained by molding thermoplastic resin fibers (example: polyester fibers) into fiber balls. When thermoplastic resin fibers are formed into fiber balls, crimpable fibers are used for the fibers in the fiber balls. As a result, it is possible to form a fiber ball in which the projecting fiber portion easily contracts when pressure is applied and when the pressure is released, the projecting fiber portion can be easily extended. For example, by controlling a molding condition or the like, a massive fiber 40 which is a fiber ball having the core portion 41 and the protruding fiber portion 42 can be formed.

As a preferable aspect in the present embodiment, the fibers of the core portion 41 in the massive fiber 40 and the fibers of the projecting fiber portion 42 are the same. Therefore, since the fibers are continuously connected from the core portion 41 to the projecting fiber portion 42, it is possible to easily catch the high viscosity excretory fluid by the projecting fiber portion 42 and to guide it to the core portion 41. At the same time, since the predetermined projecting fiber portion 42 and the core portion 41 can be more accurately formed, the core portion having a high fiber density can be more reliably prevented from collapsing, and the projecting fiber portion having a low fiber density can be easily collapsed. be able to. Thereby, when pressure is applied to the massive fiber layer, the gaps of the protruding fiber portions are appropriately shrunk to form a cushion, which can appropriately absorb the pressure and thereby lessen pressure on the core portion. Can.

As a preferable mode in the present embodiment, the fibers constituting each of the plurality of massive fibers 40 are not heat-fused. This allows the fibers to easily shrink and stretch in response to the application and release of pressure. Then, when pressure is applied to the disposable diaper 1, the fibers of the projecting fiber portion 42 can be easily shrunk, and pressure can be less easily applied to the core portion 41. Moreover, when the space | gap of the protrusion fiber part 42 and the space | gap between the core parts 41 absorb and expand | swell high viscosity waste fluid, it can suppress that the intersection of fibers prevents expansion.

In addition, one part or all part of the fibers which comprise each of several lump fiber 40 may be joined. In that case, the massive fibers 40 can be provided with compression resistance or compression repulsion. Examples of the bonding method include a method of heat-sealing fibers and a method of bonding fibers (a binder fiber, an adhesive, and the like). Thereby, when using the disposable diaper 1 (example: body pressure of the wearer), it is possible to suppress a decrease in the specific volume (porosity) of the massive fiber layer 4b and a decrease in the absorption and retention performance of the massive fiber layer 4b associated therewith. it can.

An adhesive (example: hot melt adhesive) is preferably applied to the interface between the massive fiber layer 4b and the surface sheet 2 and / or the interface between the massive fiber layer 4b and the absorbent core 4a. Thereby, the massive fiber 40 contained in the massive fiber layer 4b can be fixed. From the viewpoint of permeation of waste fluid including high viscosity waste fluid, it is preferable that the adhesive is not applied to the entire interface, and is applied, for example, in a pattern of dots, spirals, stripes, and the like. Examples of the method of applying the adhesive include spiral coating, coater coating, curtain coater coating, summit gun coating and the like. 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 surface sheet 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 surface sheet 2 is relatively small, the space of the massive fiber layer 4b becomes difficult to be used for absorption and transfer of high viscosity excretory fluid by the adhesive. Can be suppressed. As a result, the massive fiber layer 4b can quickly capture and hold the high-viscosity waste fluid. In addition, 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 absorbent has high hydrophilicity. The water of high viscosity excrement fluid and other excrement can be easily transferred to the core 4a.

The thickness, basis weight and the like of the massive fiber layer 4b are appropriately adjusted in accordance with the required absorption amount of the high viscosity excretory fluid and the like. 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 increases, the amount of absorption of the high-viscosity waste fluid increases, but the wearing feeling tends to decrease. The basis weight of the massive fiber layer 4b is, for example, 25 to 500 g / m ² . The higher the basis weight of the massive fiber layer 4b, the easier it is to retain the high-viscosity excretory fluid, but the wearing feeling tends to decrease. The thickness, basis weight and the like of the massive fiber layer 4b may be constant throughout or may be partially different.

Next, the manufacturing method of disposable diaper 1 concerning this embodiment is explained. FIG. 6 is a schematic view showing a configuration example of an absorbent manufacturing apparatus according to the embodiment.

The first step is the step of forming the absorbent core body 411. As shown in FIG. 6, for forming the absorbent core body 411, a suction drum 110 rotating in the transport direction MD and an absorbent material supply unit 120 having a hood covering the suction drum 110 are used. Recesses 112 are formed on the circumferential surface 111 of the suction drum 110 at a required pitch in the circumferential direction as a mold for packing 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 suctioned to the recess 112. Ru. The absorbent material supplied from the absorbent material supply unit 120 has a predetermined mass of the hydrophilic fiber F supplied from the crusher (not shown) and the superabsorbent polymer P supplied from the particle supply unit 121. Contain in mixing ratio. Thus, the absorbent core body 411 is formed in the recess 112. The absorbent core body 411 contains the hydrophilic fiber F and the superabsorbent polymer P in a mixed state. The absorbent core main body 411 formed in the concave portion 112 is transferred onto the lower layer core wrap 91 advancing in the transport direction MD by the action of the transfer sampling portion 150. A hot melt adhesive is coated on the upper surface of the lower layer core wrap 91, and the absorbent core body 411 is bonded onto the lower layer 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, which 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 laminate in which the upper core wrap 92, the absorbent core main body 411 and the lower core wrap 91 are sequentially stacked is formed. This continuous body is cut out 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 to apply an adhesive on the absorbent core body 4a-1. An adhesive application device 302 is used to apply the adhesive. The adhesive application device 302 applies, for example, a hot melt adhesive, for example, in a spiral pattern, for example, in a spiral pattern.

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

Through each of the above steps, the absorbent body 4 having the absorbent core 4a and the massive fiber layer 4b laminated on one surface of the absorbent core 4a is manufactured. Manufacture of the disposable diaper 1 using the absorber 4 can be implemented according to the well-known method conventionally known.

In a preferable mode of the present embodiment, as shown in FIG. 4, in the absorbent body 4, the massive fiber layer 4 b is provided so as to cover the entire skin-side surface of the absorbent core 4 a. However, the structure of the absorber 4 (mass fiber layer 4b) is not limited to this example, It can change suitably.

FIG. 7 is a view showing another configuration example of the absorber of the disposable diaper 1. FIG. 7 (a) is a plan view of the absorber 4A, and FIG. 7 (b) is a sectional view taken along line VIIb-VIIb of the absorber 4A. In the absorbent body 4A, the massive fiber layer 4bA is provided in a part of the region corresponding to the intermediate 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 located closer to the back side 13 than the center. The absorber 4A can suppress the spread of the high viscosity excretory fluid excreted from the wearer, and can absorb the high viscosity excretory fluid mainly in the massive fiber layer 4bA.

FIG. 8 is a view showing still another configuration example of the absorber of the disposable diaper 1. FIG. 8 (a) is a plan view of the absorber 4B, and FIG. 8 (b) is a sectional view taken along line VIIIb-VIIIb of the absorber 4B. In the absorbent body 4B, the massive fiber layer 4bB is provided in a part of the region corresponding to the middle portion 12 of the disposable diaper 1 on the skin-side surface of the absorbent core 4a. The portion provided with the massive fiber layer 4bB is, for example, a portion extending in the longitudinal direction L at both ends in the width direction W in the region corresponding to the middle portion 12 of the disposable diaper 1 closer to the back side 13 than the center. It is a part to be located. Absorbent body 4B can control that high viscosity excretory fluid excreted from a wearer leaks over a pair of leak-

proof walls

7a and 7b. Therefore, the absorbent body 4B is particularly useful as a diaper for a relatively high-aged baby who takes a horizontal position and opens and closes a leg.

FIG. 9 is a view showing still another configuration example of the absorber of the disposable diaper 1. FIG. 9 (a) is a plan view of the absorber 4C, and FIG. 9 (b) is a cross-sectional view of the absorber 4C taken along line IXb-IXb. In the absorbent body 4C, the massive fiber layer 4bC is provided on a part of the surface of the absorbent core 4a on the skin side corresponding to the back side 13 of the disposable diaper 1. Absorbent body 4C can control that high viscosity excretory fluid excreted from a wearer flows toward a wearer's back direction. Therefore, the absorber 4C is particularly useful as a diaper for a relatively low age baby who takes a posture of sleeping on the back well.

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 <mass fiber>
Bulk fiber was produced in the following manner. The polyester fiber (fineness 7.4 T, fiber length 32 mm) whose surface is hydrophilized is granular-cottonized with an air flow type granulator (Ball Fibers Forming Machine CMM1 manufactured by Masias), and bulk fibers are produced according to the difference in molding conditions. I got A to D.

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

Absorbent core
An absorbent core was produced in the following manner. Cottony pulp obtained by crushing fluff pulp (manufactured by International Paper Co., Ltd .: Super Soft) and super absorbent polymer (manufactured by Sumitomo Seika Chemicals Co., Ltd .: SA50) were mixed so that both were uniformly dispersed. After that, they are laminated to produce a laminate having a length of 300 mm, a width of 120 mm, a cotton-like pulp basis weight of 250 g / m ² ± 3% and a superabsorbent polymer basis weight of 250 g / m ² ± 3%. did. The laminate produced in this manner was sandwiched between two tissues coated with a hot melt adhesive on the surface on the laminate side, and then press-molded to a thickness of 2.5 mm with a pressing device.

<Production of Samples of Examples and Comparative Examples>
The samples of Examples 1 to 4 and Comparative Example 1 were manufactured by the following method.
(1) Example 1: A plurality of massive fibers A in an area of 120 mm long and 100 mm wide on the upper side of the central portion of the above absorbent core, so that the basis weight is 100 g / m ² ± 3% Stacked. Then, the surface sheet coated with the hot melt adhesive in a pattern in which only a portion of the plurality of massive fibers is not adhered is bonded to the upper surface of the absorbent core.
(2) Example 2: The same as Example 1 except that the massive fiber A was changed to the massive fiber B.
(3) Example 3: The same as Example 1 except that the massive fiber A was changed to the massive fiber C.
(4) Example 4: The same as Example 1 except that the massive fiber A was changed to the massive fiber D.
(5) Comparative Example 1: The same as Example 1 except that the lump fiber A was changed to cotton ball (Suzuran Co., Ltd .: Tin-Lan cotton ball No. 3).

(II) Evaluation of Sample (II-1) Evaluation of Bulk Fiber First, the bulk fibers of Examples 1 to 4 and Comparative Example 1, that is, bulk fibers A to D, cotton balls, the average diameter 2r of core portion, bulk fiber The average diameter 2 × (r + d) of the above and the average thickness d of the protruding fiber portion were determined by the following method.

<Average diameter 2r of core part>
(I) In the digital microscope VHX-2000 (KEYENCE CORPORATION), the lens magnification was set to a magnification at which a massive fiber to be measured enters the screen (example: 20 to 200 times).
(Ii) The image size was set to 1600 pixels (H) × 1200 pixels (V).
(Iii) The massive fiber to be measured was set on the permeation measurement unit, and an image was taken.
(Iv) After saving the image and recalling it, "measurement", "automatic area measurement", "brightness", and "start measurement" were selected.
(V) A binarization threshold was set to 0, and extraction parameters were binarized by checking “dark”, “hole filling”, and “small particle removal”.
(Vi) The automatically calculated extraction area area was recorded as the projected area of the massive fiber.
(Vii) The above (iii) to (vi) were performed on ten massive fibers, and the projected area of ten massive fibers was determined. The average value Av of the projected areas for these 10 pieces was determined.
(Vii) The diameter conversion value when the average value Av of the obtained projected area is the area of a circle is determined by (4 × Av / π) ^0.5 , and the diameter 2r (approximate value) of the core portion 41 did.

<Average diameter of massive fiber 2 × (r + d)>
(I) In the digital microscope VHX-2000 (KEYENCE CORPORATION), the lens magnification was set to a magnification at which a massive fiber to be measured enters the screen (example: 20 to 200 times).
(Ii) The image size was set to 1600 pixels (H) × 1200 pixels (V).
(Iii) The massive fiber to be measured was set on the permeation measurement unit, and an image was taken.
(Iv) The image was stored, recalled, and the longest length (long diameter) of the massive fiber was measured.
(V) The longest length (minor axis) of the massive fiber was measured under the condition orthogonal to the measurement line of the major axis.
(Vi) The above (iii) to (v) were carried out on ten massive fibers, and the major diameter and the minor diameter of the ten massive fibers were determined. The average value r _L of the major axes of these 10 pieces and the average value r _S of the minor axes were determined.
(Vii) Determine 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, and the diameter of the massive fiber 2 × (r + d) (approximate value) ).

<Average thickness d of protruding fiber portion>
(I) Subtracting the diameter 2r (approximate value) of the core portion 41 from the diameter 2 × (r + d) (approximate value) of the massive fiber described above to halve the thickness of the protruding fiber portion 42 d (approximate value) was calculated.

<Result>
An example of an image taken when obtaining the average diameter 2r of the core portion, the average diameter 2 × (r + d) of the massive fibers, and the average thickness d of the protruding fiber portions and an example of an image obtained by binarizing the image , Shown in FIG. FIG. 10 shows an optical microscope image of the massive fibers 40 in an example of each sample of Examples 1 to 4 and Comparative Example 1, and an image obtained by subjecting them to binarization and processing. As illustrated, in each of the samples of Examples 1 to 4, the projecting fiber portion is widely present around the core portion, but in the sample of Comparative Example 1, the projecting fiber portion is very few. It turned out not. The average diameter 2r of the core portion and the average thickness d and d / 2r of the protruding fiber portion are shown in Table 1 below. It has been found that the range of d / 2r is preferably 0.4 to 2, more preferably 0.7 to 1.5.

(II-2) Evaluation of Each Sample of Examples 1 to 4 and Comparative Example 1 For each of the samples 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 are as follows. I asked for.

<Specific volume>
The following measurements were carried out for each of massive fibers A to D and cotton balls of Examples 1 to 4 and Comparative Example 1.
(I) A plurality of massive fibers, a total of 0.180 g (equivalent to 100 g / m ² ), were uniformly charged into a cylinder having a diameter of 48 mm (cross-sectional area 18 cm ² ), and used as a measurement sample. The measurement sample simulates the massive fiber layer 4b.
(Ii) Thickness Measurement Device: The thickness of a measurement sample at the center of a cylinder was measured with a dial thickness gauge large type JB (manufactured by Ozaki Mfg. Co., Ltd.). 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 instrument. This thickness was taken as the reference thickness. The specific volume at this stage is the above-mentioned standard specific volume, and was calculated from the actually measured standard thickness by the following formula.
Reference specific volume (cc / g) = π × {cylinder radius (cm)} ² × reference thickness measured (cm) / mass of sample (0.180 g)
(Iii) Next, with a weight of a predetermined mass 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, the thickness of the measurement sample Was measured. At this time, a predetermined load was applied by the weight and the weight of the measurement unit of the thickness measuring device. This thickness was taken as the loading thickness. The specific volume at this stage is the above-mentioned load specific volume, and was calculated from the measured load thickness by the following formula.
Load specific volume (cc / g) = π × {cylinder radius (cm)} ² × measured load thickness (cm) / mass of sample (0.180 g)

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

<Change rate of specific volume ratio>
Based on the graph of load specific volume to pressure (load) calculated by the above method, the rate of change of specific volume ratio, which is the ratio of change of specific volume ratio to change of pressure (load), was calculated. For example, in the case of the change rate of the specific volume ratio in the case where the change in pressure (load) is 3 g / cm ² to 5 g / cm ² , it was calculated by the following equation.
(Percent change ((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 massive fibers, the number of massive fibers per unit volume, and the porosity between core portions of massive fiber layers were determined by the following method.

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

<Number of bulk fibers per unit volume>
The number N of aggregated fibers per unit volume in the aggregated fiber layer was calculated by the following equation.
N (pieces / cm ³ ) = n (pieces) / (0.180 (g) × reference specific volume (cc / g))
However, n (piece) is the number of objects of the massive fiber thrown into the cylinder by the above-mentioned <specific volume> (i).

<Void ratio between core parts>
The ratio of the space between the plurality of core portions in the massive fiber layer, that is, the inter-core portion porosity F1 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 massive fibers per unit volume.

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

<Evaluation method of penetration time, surface reversion rate and retention rate>
(I) For each of the samples of Examples 1 to 4 and Comparative Example 1 (provided with a massive fiber layer including a surface sheet, a plurality of massive fibers, and an absorbent core), a wire mesh of 10 mesh at the bottom on the central portion A cylinder with a diameter of 60 mm attached was placed.
(Ii) 15 g of artificial soft stool whose viscosity was adjusted to 2000 mPa · s was precisely weighed and injected into a cylinder with a syringe.
(Iii) Start the stopwatch at the same time as starting the injection of artificial soft stool, measure 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, penetrate the measured time It was time. However, when the wire mesh was not exposed even after 3 minutes, it was regarded as the end.
(Iv) Remove the cylinder 3 minutes after the injection of artificial soft stool, place a 10 cm × 10 cm filter paper (made by As One: NO 1 filter paper) on the sample, and further load 20 g / cm ² on the filter paper The weight which became and was mounted and it left still for 30 seconds.
(V) After 30 seconds, the mass of the filter paper was measured, the mass of the original filter paper was subtracted, and the amount of artificial soft stool return was calculated. The value of the obtained amount of return was divided by the amount of injection of artificial soft stool to obtain the surface return rate.
(Vi) Next, the surface sheet was peeled off, and a massive fiber layer (including artificial soft feces) in a circular range of 85 mm in diameter centered on a cylinder was taken out and the mass was measured.
(Vii) Subtract the mass (0.567 g) of the original massive fiber layer before absorbing artificial soft feces from the measured mass to calculate the amount of artificial soft feces retained by the massive fiber layer did. The value of the obtained holding amount was divided by the injection amount of artificial soft stool to obtain a holding rate.

<Preparation method of artificial soft stool>
However, the preparation method of 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 exchange 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 Of 0.05% by mass, and 10.0% by mass of powdered cellulose. Then, the viscosity of the agent was adjusted to 2000 mPa · s with ion-exchanged water to make an artificial soft stool.

Table 2 summarizes the results of the above-described measurements of each of the samples of Examples 1 to 4 and Comparative Example 1, the massive fibers A to D, and the cotton ball.

11 is a graph showing the load on the massive fiber layer 4b in each of the samples of Examples 1 to 4 and Comparative Example 1 (the relationship between the pressure and the specific volume. The horizontal axis represents the load (pressure) (g / g). a cm ^2), and the vertical axis indicates the specific volume (cc / g). rhombus (◇) example 1, a square (□) example 2, triangles (△) example 3, circles (〇) Is the example 4 and the inverse triangle (▽) is the comparative example 1. In the samples of the examples 1 to 4, the specific volume decreased rapidly at the beginning of the increase in load (pressure), but the load (pressure) In the sample of Comparative Example 1, the relative volume decreased at the same rate as the load (pressure) increased.

FIG. 12 is a graph showing the relationship between the load (pressure) in 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 load (pressure) of 3 g / cm ² . The horizontal axis is load (pressure) (g / cm ² ), and the vertical axis is a specific volume ratio (dimensionless). The rhombus (は) is Example 1, the square (□) is Example 2, the triangle (Δ) is Example 3, the circle (〇) is Example 4, and the inverse triangle (▽) is Comparative Example 1. The normalization makes the difference between the tendency of the graphs of Examples 1 to 4 and the tendency of the graph of Comparative Example 1 more apparent.

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

This is because, in the samples of Examples 1 to 4, at the beginning of the increase of the load (pressure), the specific volume is sharply reduced due to the contraction of the protruding fiber part, but the increase of the load (pressure) proceeds Then, when the protruding fiber portion becomes difficult to shrink, the core portion shrinks, and it is considered that the decrease in specific volume is gradual. On the other hand, in the sample of Comparative Example 1, the core portion shrinks from the initial stage of the increase in load (pressure) because there are almost no protruding fiber portions, and it is considered that the core portion decreases at the same rate. That is, the effects of the protruding fiber portions of Examples 1 to 4 were confirmed.

Then, as shown in Table 1, in the samples of Examples 1 to 4, the surface reversion 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, it is possible to suppress the exudation (rewet) of the high viscosity excrement fluid to the surface sheet 2 while maintaining or improving the absorption performance to the high viscosity excrement fluid by the massive fiber layer 4b of Examples 1 to 4 became.

From the graphs in Table 1 and FIGS. 11 and 12, the rate of change in specific volume ratio when the load (pressure) is changed from 3 g / cm ² to 5 g / cm ² is −0.12 to −0. .025 (g / cm ² ) ^-1 is preferable, and the rate of change in specific volume ratio with changing the load (pressure) from 25 g / cm ² to 30 g / cm ² is -0.02 to 0 ( The range of g / cm ² ) ^-1 was preferred. The specific volume ratio at a load (pressure) of 25 g / cm ² was preferably in the range of 0.2 or more and 0.7 or less. Load (pressure) 3 g / porosity when the cm ² is less than 40%, preferably in the range of 80% or less, the load (pressure) porosity when the 25 g / cm ² is more than 2%, less 60% The range was more preferred.

1 Disposable diapers (absorbent articles)
4 Absorbent 4a Absorbent Core 40 Aggregate Fiber 4b Aggregate Fiber Layer 41 Core Part 42 Protruding Fiber Part

Claims

An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body positioned between the top sheet and the back sheet,
The absorber is
An absorbent core,
A massive fiber layer located on the surface sheet side of the absorbent core and containing a plurality of massive fibers;
Each of the plurality of massive fibers is
A core portion formed of massive fibers, high in fiber density, and resistant to crushing;
Formed of crimped fibers protruding outward from the periphery of the core portion, and having a low fiber density and a collapsible protruding fiber portion;
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 taken as a reference specific volume, and the bulk when a pressure greater than 3 g / cm 2 is applied to the massive fiber layer A specific volume of the fiber layer is a load specific volume, a ratio of the load specific volume to the reference specific volume is a specific volume ratio, and a ratio of a change of the specific volume ratio to a change of pressure applied to the massive fiber layer is a change ratio When you
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 ) −1 or more, −0.025 (G / cm 2 ) -1 or less,
The second rate of change, which 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, 0 (g / cm 2 ) cm 2 ) less than -1 ,
Absorbent article.
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 portion in the massive fiber and the fibers of the projecting fiber portion are the same.
The absorbent article according to claim 1 or 2.
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.
The fibers constituting each of the plurality of massive fibers are not heat-fused together,
The absorbent article according to any one of claims 1 to 4.
When the ratio of the space between the core portions in the massive fiber layer is taken as 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 is 2% or more and 60% or less when the pressure applied to the massive fiber layer is 25 g / cm 2 .
The absorbent article according to any one of claims 1 to 5.
The basis weight of the adhesive between the bulk fiber layer and the top sheet is lower than the basis weight of the adhesive between the bulk fiber layer and the absorbent core.
The absorbent article according to any one of claims 1 to 6.
At least a portion of the surface sheet has a plurality of through holes penetrating in a thickness direction toward the massive fiber layer,
The absorbent article according to any one of claims 1 to 7.
The massive fibers are fiber balls,
The absorbent article according to any one of claims 1 to 8.