TW201927268A - Absorbent article - Google Patents

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 article

The present invention relates to an absorbent article.

An absorbent article which absorbs liquid excrement with high viscosity is known. For example, the absorbent article of Patent Document 1 includes a liquid-permeable top sheet and a liquid-impermeable back sheet, and an absorber located between the front sheet and the back sheet. The absorber includes: absorbent A core and a porous plasmid sublayer on the surface sheet side of the absorbent core. Examples of porous particles in the porous particle layer include fibrous spheres and porous cellulose particles. According to Patent Document 1, the high-viscosity liquid excrement excreted toward the surface sheet of the absorbent article diffuses the porous plasmid sublayer and is temporarily stored in the porous plasmid sublayer. At this time, the voids between the porous particles and the voids within the porous particles function as a flow path for liquid excrement. Thereby, the liquid excrement quickly diffuses the porous plasmid sublayer and moves toward the absorbent body with high efficiency. However, among the components of the liquid excrement, water easily moves from the porous plasmid sublayer to the absorbent body, but solid components such as fibrous matter are captured by the porous plasmid sublayer and easily retained. As a result, the action of the fluid as a liquid excrement (mainly a solid component) remaining in the porous plasmid sublayer becomes dull. Accordingly, when pressure is applied to the absorbent article, the staining (repermeation) of the liquid excrement from the porous plasmid sublayer to the liquid-permeable surface sheet is suppressed.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2015-188709

[Problems to be Solved by the Invention]

Patent Document 1 discloses that a liquid excrement having a high viscosity has a property of being easily separated into a solid component and a liquid component. However, there may be cases where it is difficult to separate the liquid excrement with a high viscosity into solid and liquid components. Liquid excreta of high viscosity (hereinafter also referred to as "high-viscosity excretion fluid"), which is difficult to separate into solid and liquid components, is not only high-viscosity excretion fluid, but is excreted toward the surface sheet of an absorbent article The solid and liquid components can be captured by the voids between the porous particles and the voids within the porous particles, and retained. When an absorbent article holding such a high-viscosity excretion fluid is applied with pressure from the outside, the porous particles are compressed, the volume of the voids in the porous particles is reduced, and the high-viscosity excretion liquid in the voids faces the porous particles. Concerns about leakage on the outside of the layer. In addition, since there is no obstacle to movement in the space between the porous particles, the high-viscosity excretion fluid in the space may leak out to the outside of the porous particle layer. In this case, the leaked high-viscosity fecal fluid is dyed out toward the surface sheet, thereby causing back osmosis.

Here, an object of the present invention is to provide an absorbent article which can maintain or improve the absorption performance of a high-viscosity excretory fluid, and suppress the high-viscosity excretory fluid from being stained (back osmosis) toward a surface sheet.

[Means to solve the problem]

The absorbent article of the present invention is (1) an absorbent article comprising a liquid-permeable top sheet and a liquid-impermeable back sheet, and an absorber positioned between the front sheet and the back sheet, and the absorbent The body is provided with an absorbent core and a block fiber layer on the surface of the surface sheet side of the absorbent core and including a plurality of block fibers, and the plurality of block fibers each include: a block fiber A core with a high fiber density and difficulty in crushing; and a crimpable fiber protruding from the periphery of the core to the outside, the fiber density is low and the fiber is easily protruded by crushing; adjacent ones The bulk fibers are in contact with each other through the protruding fiber portions, and a specific volume of the bulk fiber layer when a pressure of 3 g / cm ² is applied to the bulk fiber layer is set as a reference specific volume, and the bulk fibers are directed toward the bulk fiber. layer plus the bulk volume ratio of the fibrous layer at a larger pressure 3g / cm ² load is set to a specific volume, the volume ratio of the load provided to the reference volume ratio than the ratio of the volume ratio, the ratio of the Change change change in volume ratio with respect to the pressure applied to the bulk of the fibrous layer is set to a ratio of the time rate of change, is applied to the bulk of the fibrous layer to 5g pressure is the rate of change of ² 3g / cm ² / cm That is, the first change rate is -0.12 (g / cm ² ) ^-1 or more and -0.025 (g / cm ² ) ^-1 or less. The change in the pressure applied to the bulk fiber layer is 25 g / cm ² to 30 g / The above-mentioned change rate at cm ² , that is, the second change rate is -0.02 (g / cm ² ) ^-1 or more, and less than 0 (g / cm ² ) ^-1 .

In the present absorbent article, in the bulk fiber layer, the adjacent bulk fibers are contacted through the protruding fiber portion, and the fibers of the protruding fiber portion are rebounded and entangled with each other, and are adjacently connected to each other. Between the core portions, voids (voids between the core portions) caused by fibers protruding from the fiber portion are formed. At this time, the fibers protruding from the fiber portion are made of crimpable fibers. Since the fiber density is relatively low, when a pressure (load) is applied to the bulk fiber layer, it can be easily shrunk in response to the pressure. Therefore, since the protruding fiber portion contracts to absorb the pressure, the pressure hardly affects the core portion, and deformation of the core portion can be suppressed. Here, when pressure is applied to the bulk fiber layer, the specific volume of the bulk fiber layer decreases. However, in the aspect of the reduction, first, when the pressure is small, the specific volume is mainly reduced by shrinking the protruding fiber portion which has a lot of voids and is easy to shrink, thereby reducing the specific volume. When the pressure is large, the protruding fiber portion is sufficiently contracted, and then the specific volume is further reduced mainly by shrinking the core portion with few voids and difficult contraction. Therefore, the decrease in the specific volume of the bulk fiber layer is performed in a stepwise manner such that the shrinkage of the protruding fiber portion and the shrinkage of the core portion are performed. In the present absorbent article, the first change rate when the pressure applied to the bulk fiber layer is 3 g / cm ² to 5 g / cm ² is -0.12 (g / cm ² ) ^-1 or more, and -0.025 (g / cm ² ) ^-1 or less, the second change rate when the pressure applied to the bulk fiber layer is 25 g / cm ² to 30 g / cm ² is -0.02 (g / cm ² ) ^-1 or more and less than 0 (g / cm ² ) ^-1 . However, in a state where a pressure of 3 g / cm ² is applied to the bulk fiber layer, the simulated pressure is hardly applied to an absorbent article in which the wearer is standing, and a pressure of 25 g / cm ² is applied to the bulk fiber layer. , Is a state that simulates a situation where a large amount of pressure is applied to the absorbent article in which the wearer is sitting. And the change of pressure (load) from 3g / cm ² to 5g / cm ² changes according to the shrinkage of the protruding fiber portion, and the change of pressure (load) from 25g / cm ² to 30g / cm ² changes according to the shrinkage of the core. .
This absorbent article absorbs high-viscosity liquid excreta, which is a highly viscous liquid excreta, which has a property that is difficult to separate into solid components and liquid components, in the core of the bulk fibers in the bulk fiber layer. The voids and the voids in the protruding fiber portion can capture and hold high-viscosity excretion fluid. At this time, the core portion with the highest fiber density in the bulk fiber layer has a high fiber density, so when there is sufficient capacity, the high-viscosity excretion fluid once held in the protruding fiber portion can be removed from the protrusion. Adjacent portions of the fiber portion absorb and hold. In addition, such an absorbent article shrinks the shrinkable fibers protruding from the fibrous portion by applying pressure to the pressure while applying pressure from a change in the posture of the wearer while maintaining the high-viscosity fecal fluid. , And become a buffer, you can absorb this pressure. Therefore, the pressure can be hardly applied to the core. This makes it difficult to press the high-viscosity excretion liquid held in the voids in the core toward the outside. Furthermore, by shortening the distance between the bulk fibers, the fiber density of the voids protruding from the fiber portion becomes higher, that is, by increasing the fiber density around the core portion, leakage from the core portion can be suppressed. Here, in the case where most of the high-viscosity excretion fluid is held in the voids of the protruding fiber portion, the high-viscosity excretion fluid held in the voids of the protruding fiber portion may be easily extruded to the outside due to the shrinkage of the protruding fiber portion. . However, since this high-viscosity excretion liquid is moved downward (absorber side) by the protruding fiber portion by its own weight, it is in a state that the protruding fiber portion is covered from above (surface sheet side), that is, it is covered above. status. As a result, even if the space between the protruding fiber portions is contracted, the protruding fiber portion (cap) above can prevent the high-viscosity excretion fluid from leaking to the surface sheet side. The high-viscosity excretion fluid that is nowhere to go is the gap between the core of the block fiber and the protruding fiber portion in the part where the load is not applied (for example, the rupture of the buttocks), and it can penetrate the protruding fiber of the block fiber in the middle. Department while moving. This makes it difficult to be pushed outward. Such an absorbent article can maintain or improve the absorption performance of high-viscosity excretion fluid, and further suppress the staining of the liquid excretion toward the surface sheet. In addition, for a liquid excrement having the property of being easily separated into a solid component and a liquid component, the solid component is mainly absorbed by the bulk fiber layer, and the liquid component is mainly absorbed by the absorbent core.

However, the first rate of change is less than -0.12 (g / cm ² ) ^-1 , that is, a case where the absolute value exceeds 0.12, because the ratio caused by the shrinkage of the protruding fiber portion with respect to the change in pressure applied to the bulk fiber layer is The decrease in the volume ratio is too large (there are more gaps in the protruding fiber portion, or the amount of fibers in the protruding fiber portion is small, etc.), so it becomes easier to release the retained high-viscosity excretion fluid. On the other hand, the first rate of change is more than -0.025 (g / cm ² ) ^-1 , that is, the absolute value is less than 0.025, because of the shrinkage of the protruding fiber portion due to the change in pressure applied to the bulk fiber layer. The reduction in the specific volume ratio that occurs is too small (there is less space in the protruding fiber portion, or there is more fiber in the protruding fiber portion, etc.), so it becomes difficult to sufficiently maintain the high-viscosity excretion fluid. The second rate of change is less than -0.02 (g / cm ² ) ^-1 , that is, when the absolute value exceeds 0.015, because the specific volume is caused by the shrinkage of the core portion due to the change in pressure applied to the bulk fiber layer. The reduction of the ratio will be too large (there is a lot of voids in the core, or the amount of fibers in the core is small, etc.), so the core is easily deformed, and the high-viscosity excretion liquid becomes easy to dye.

The absorbent article of the present invention (2) is the absorbent article according to the above (1), wherein the average thickness of the protruding fiber portion on the surface of the core portion of the block fibers is 0.4 of the average diameter of the core portion. It can be more than twice and less than two times.
In this 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. In the case where the average thickness of the protruding fiber portion is within this range, a high-viscosity excretion fluid can be appropriately maintained in the gap of the protruding fiber portion, and when pressure is applied to the bulk fiber layer, the gap of the protruding fiber portion shrinks moderately. As a buffer, the pressure can be appropriately absorbed, thereby preventing the pressure from being applied 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 voids of the protruding fiber portion cannot be sufficiently ensured, pressure is easily applied to the core portion, and high-viscosity excretion liquid is easily removed from the core portion. Stained out. When the average thickness of the protruding fiber portion is more than twice the average diameter of the core portion, in a state where most of the high-viscosity excretion fluid is maintained in the protruding fiber portion, the protruding fiber portion shrinks, and the high-viscosity excretion liquid becomes easy Dyed from protruding fiber.

The absorbent article of the present invention (3) is the same as the absorbent article of (1) or (2), wherein the fibers of the core portion and the fibers of the protruding fiber portion of the bulk fibers may be the same.
In this 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 fecal fluid can be captured by the protruding fiber portion, and it is easier to guide toward the core portion. At the same time, since the predetermined protruding fiber portion and the core portion can be formed more reliably, it is more difficult to crush the core portion having a higher fiber density, and the protruding fiber portion having a lower fiber density can be easily crushed. . Thereby, when pressure is applied to the bulk fiber layer, the voids of the protruding fiber portions are moderately contracted to serve as a buffer, and the pressure can be appropriately absorbed, thereby preventing the pressure from being applied to the core portion.

The absorbent article of the present invention, (4) the absorbent article according to any one of (1) to (3) above, wherein the specific volume ratio when the pressure applied to the bulk fiber layer is 25 g / cm ² , It is 0.2 or more and 0.7 or less may be sufficient.
In this absorbent article, the specific volume ratio when the pressure is 25 g / cm ² is 0.2 to 0.7. When the specific volume ratio is within this range, when pressure is applied to the bulk fiber layer, the voids protruding from the fiber portion can be appropriately contracted. Therefore, in the protruding fiber portion, the fiber density becomes high, and it is possible to prevent the high-viscosity excretion liquid in the voids of the protruding fiber portion from being dyed to the outside. In addition, since the protruding fiber portion acts as a buffer in the core portion and appropriately absorbs pressure, the pressure becomes difficult to apply to the core portion, and it is possible to suppress high-viscosity excretion fluid in the voids of the core portion from being dyed to the outside. At this time, when the ratio of the load to the volume is less than 0.2, the protruding fiber portion shrinks due to the pressure, and the high-viscosity excretion liquid is mainly easily dyed from the protruding fiber portion. When the ratio of the load to the volume exceeds 0.7, the shrinkage of the protruding fiber portion due to the pressure is too small, and the high-viscosity excretion liquid is mainly easy to be dyed from the core portion.

The absorbent article of the present invention (5) The absorbent article according to any one of (1) to (4) above, the fibers constituting each of the plurality of block fibers may not be thermally fused with each other.
In this absorbent article, the fibers of the block fibers are not thermally fused with each other. Therefore, when pressure is applied to the absorbent article, the fibers protruding from the fiber portion can be easily shrunk, so that the pressure is not applied to the core portion. . In addition, when the space between the fiber portions and the space between the core portions are protruded, the high-viscosity fecal fluid is absorbed and expanded, and the intersections between the fibers can be prevented from hindering the expansion.

The absorbent article of the present invention (6) is the absorbent article according to any one of (1) to (5) above, wherein a ratio of a void between the core portions in the bulk fiber layer is set to a void ratio When the pressure applied to the bulk fiber layer is 3 g / cm ² , the first void ratio is 40% or more and 80% or less, and the pressure applied to the bulk fiber layer is 25 g / cm ² . The rate is 2% or more and 60% or less is acceptable.
In this absorbent article, the first porosity of the bulk fiber layer is 40% to 80%, and the second porosity is 2% to 60%. Since the porosity when pressure (3g / cm ² ) is hardly applied to the bulk fiber layer is 40% to 80%, sufficient core can be ensured despite capturing high-viscosity fecal fluid, and it is possible to buffer pressure. Make sure that the fiber section is fully projected. And when the pressure is applied to the bulk fiber layer (25g / cm ² ), the porosity is 2% to 60%. Therefore, although the high-viscosity excretion fluid is maintained, sufficient protrusion of the fiber portion is ensured, and the protruding fiber portion can be sufficiently contracted. Application of pressure to the core can be suppressed. Here, when the bulk fiber layer has a porosity of less than 40% when the pressure is 3 g / cm ² , when the pressure is increased, a space capable of shrinking properly cannot be ensured in the protruding fiber portion, and when it exceeds 80%, the core is The part cannot ensure a space capable of sufficiently absorbing the high-viscosity excretion fluid. When the porosity of the bulk fiber layer is less than 2% when the pressure of the block fiber layer is 25 g / cm ² , the space where the high-viscosity excretion liquid can be sufficiently maintained cannot be ensured in the protruding fiber portion. It becomes difficult to hold the excretory fluid in the space between the protruding fiber portions.

The absorbent article according to the present invention (7) is the absorbent article according to any one of (1) to (6) above, wherein the basis weight of the adhesive between the bulk fiber layer and the surface sheet is higher than the foregoing The basis weight of the adhesive between the bulk fiber layer and the absorbent core may be lower.
In this absorbent article, the basis weight of the adhesive (example: thermal fusion adhesive) between the bulk fiber layer and the surface sheet is lower than the basis weight of the adhesive between the bulk fiber layer and the absorbent core. . Therefore, it is possible to suppress the situation in which the space of the massive fiber layer cannot be used for the absorption and movement of high-viscosity excretion fluid due to the adhesive. Thereby, the massive fiber layer can quickly capture and hold the high-viscosity excretion fluid. In addition, because the basis weight of the adhesive between the absorbent core and the bulk fiber layer is relatively large, the contact area with the absorbent core is increased, and the water of high viscosity excretion liquid is easy to be absorbed in the absorbent core with higher hydrophilicity mobile.

The absorbent article of the present invention (8) is the absorbent article according to any one of the above (1) to (7), wherein at least a part of the surface sheet has a plurality of penetrations having a thickness direction toward the bulk fiber layer penetration. Holes are also available.
In the present absorbent article, since the surface sheet does not impede the permeation of the high-viscosity excretion fluid, the high-viscosity excretion fluid can be moved more quickly toward the bulk fiber layer. However, the plurality of through-holes include not only the through-holes formed as holes, but also the gaps between the fibers of a sheet having a small basis weight such as a through-hole opening.

The absorbent article of the present invention (9) is the absorbent article according to any one of the items (1) to (8) above, and the bulk fibers may be fiber balls.
In this absorbent article, since the bulk fibers are formed of fiber balls, the bulk fibers and the bulk fiber layer having a predetermined core portion and a protruding fiber portion can be easily formed.

[Effect of the invention]

According to the present invention, it is possible to provide an absorbent article which can maintain or improve the absorption performance of a high-viscosity excretion fluid, and can suppress the high-viscosity excretion fluid from being stained (back osmosis) toward the surface sheet.

Hereinafter, in the absorbent article of the example, a panty type disposable diaper (hereinafter, also simply referred to as a "disposable disposable diaper") will be described as an example of the absorbent article. However, the present invention is not limited to this example, and can be applied to various absorbent articles without departing from the scope of the subject matter of the present invention. Examples of such absorbent articles include belt-type disposable diapers, urine-absorbing pads, toilet pads, and sanitary napkins.

First, the disposable diaper 1 of the present embodiment will be described.
1 to 3 are diagrams showing a configuration example of the disposable diaper 1 of the present embodiment. However, FIG. 1 is a perspective view showing a state when the disposable diaper 1 is used, and FIG. 2 is a plan view showing an unfolded state of the disposable diaper 1, and FIG. 3 is a plan view showing the disposable diaper 1 A perspective view of the diaper 1 in a disassembled state. The disposable diaper 1 has a length direction L, a width direction W, and a thickness direction T running straight between each other in a state shown in FIGS. 2 and 3, and has a width direction W The lengthwise centerline CL extending toward the lengthwise direction L and the widthwise centerline CW extending toward the widthwise direction W through the center of the lengthwise direction L. The directions toward and away from the centerline CL in the longitudinal direction are provided as the inner direction and the outer direction of the width direction W, respectively. The directions toward and away from the center line CW in the width direction are provided as the inner direction and the outer direction of the longitudinal direction L, respectively. The disposable diaper 1 placed on a plane including the longitudinal direction L and the width direction W is referred to as "viewed from above" when viewed from above the thickness direction T, and the shape grasped from above is referred to as "Planar shape". When the "skin side" and "non-skin side" are respectively installed in the disposable diaper 1, the thickness direction T of the disposable diaper 1 is relatively close to the skin surface side of the installer and away from the skin. The meaning of the side. These directions and the like are similarly applied to the materials constituting the disposable diaper 1.

The disposable diaper 1 includes a belly portion 11 and a back portion 13, and an intermediate portion 12 between the belly portion 11 and the back portion 13. The abdominal portion 11 is a portion of the disposable diaper 1 that comes into contact with the abdomen of the installer. The middle portion 12 is a portion of the disposable diaper 1 that comes into contact with the intertrochanter portion of the installer. The back side portion 13 is a portion that comes into contact with the buttocks and / or the back of the installer in the disposable diaper 1. Both ends 11a, 11b in the width direction W of the abdominal portion 11 and both ends 13a, 13b in the width direction W of the back portion 13 are superposed along the length direction L and the thickness direction T, respectively. , Are joined to each other by a pair of joining portions 14a, 14b. In the disposable diaper 1, the end portion 11e on the opposite side of the middle portion 12 in the longitudinal direction L in the abdominal portion 11 and the opposite side of the middle portion 12 in the longitudinal direction L of the back portion 13 The end portion 13e forms a waist opening WO. Further, in the disposable diaper 1, a pair of leg openings LO and LO are formed by the two side portions 12 a and 12 b in the width direction W of the middle portion 12.

The disposable diaper 1 includes an absorbent body 10 that absorbs and retains excrement, and a cover sheet 3 and a cover sheet 6 that hold the absorbent body 10 from the non-skin side and the skin side. The cover sheet 3 and the cover sheet cover both sides of the thickness direction T of the absorbent body 10 and extend around the width direction W and the length direction L of the absorbent body 10. In the skin-side cover sheet 6, in order to expose the skin-side surface of the absorbent body 10, an approximately rectangular rectangle (or an oval shape or an elongated shape) is provided in the substantially central portion of the width direction W and the length direction L The openings 6a of the slabs allow smooth absorption of excreta. The absorptive body 10 includes a surface sheet 2 having liquid permeability, a back sheet 8 having liquid impermeability, and an absorption between the surface sheet 2 and the back sheet 8 that has liquid absorption and liquid retention properties. Body 4. The absorbent body 4 has a structure in which an absorptive core 4a on the non-skin side and a bulk fiber layer 4b on the skin side are laminated in the thickness direction T.

As the material of the surface sheet 2, the back sheet 8, the absorbent core 4a of the absorber 4, the cover sheet 3, and the cover sheet 6, known materials generally available in disposable diapers 1 can be used. That is, the material of the surface sheet 2 is exemplified by a liquid-permeable nonwoven fabric, a synthetic resin film having holes for liquid transmission, and a composite sheet of these. Examples of the material of the nonwoven fabric include natural fibers, regenerated fibers, inorganic fibers, and synthetic resin fibers. Examples of the basis weight of the surface sheet 2 include 2 to 100 g / m ^2. From the viewpoint of easy passage of high-viscosity excretion fluid, 5 to 50 g / m ^{2 is} preferable, and 8 to 20 g / m ^{2 is more} preferable. The back sheet 8 is, for example, a liquid-impermeable nonwoven fabric, a synthetic resin film, these composite sheets, or an SMS nonwoven fabric. The material of the absorptive core 4a of the absorbent body 4 is, for example, hydrophilic fibers such as pulp fibers and synthetic fibers, and superabsorbent copolymers (SAP). Examples of the basis weight of the fibers of the absorbent core 4a include 50 to 1000 g / m ² , and examples of the basis weight of the highly absorbent copolymer include 10 to 500 g / m ² . The bulk fiber layer 4b of the absorber 4 is mentioned later. The material of the cover sheet 3 is, for example, the same material as that of the surface sheet 2. As the material of the cover sheet 6, for example, the same material as that of the back sheet 8 can be used. The absorbent body 10, the cover sheet 3, and the cover sheet 6 are each joined by an adhesive, and the absorbent body 4 and the front sheet 2 and the back sheet 8 are each joined by an adhesive. The adhesive is a well-known material, and for example, a thermal fusion adhesive can be used.

The disposable diaper 1 may include a pair of leak-proof walls 7a, 7b which are liquid-impermeable, and an elastic body 9 (9a, 9b, 9c, 9d). The pair of leak-proof walls 7 a and 7 b are arranged on the skin-side surface of the surface sheet 2 on both sides in the width direction W and extend along the length direction L. The pair of leak-proof walls 7 a and 7 b are arranged apart from each other in the width direction W. The pair of leak-proof walls 7a and 7b are respectively fixed to the outer surface of the surface sheet 2 by heat welding or the like as fixed ends, and the inner ends of the width direction W are made stretchable. Free ends of the folds. In the vicinity of the respective ends of the pair of leak-proof walls 7a, 7b, a plurality of elastic bodies 7Ea, 7Eb, such as rubber threads, extending along the longitudinal direction L are arranged. The elastic body 9a and the elastic body 9b extend between the cover sheet 3 and the cover sheet 6 in the ventral portion 11 and the back portion 13, respectively, and extend in the width direction W, and are arranged at intervals in the length direction L. Be held hostage. The elastic bodies 9a and 9b expand and contract the waist opening WO. The elastic bodies 9 c and 9 d are located at both ends of the width direction W of the ventral portion 11 and the dorsal portion 13 sides of the intermediate portion 12 along the substantially longitudinal direction L and at the center of the intermediate portion 12. The portions are continuously arranged along the width direction W. The elastic bodies 9c and 9d stretch and contract the pair of leg openings LO and LO, respectively. Examples of the elastic body 9 include rubber threads.

Next, the absorber 4 will be described further. FIG. 4 is a diagram showing a configuration example of the absorbent body 4 of the disposable diaper 1. FIG. 4 (a) is a plan view of the absorbent body 4, and FIG. 4 (b) is an IVb-IVb cross-sectional view of the absorbent body 4. As described above, the absorbent body 4 includes an absorptive core 4a on the non-skin side (back sheet 8 side) and a bulk fiber layer 4b on the skin side (front sheet 2 side), which are laminated in the thickness direction T. Make up. In this embodiment, the bulk fiber layer 4b covers the entire surface sheet 2 side of the absorbent core 4a. The absorptive core 4a is liquid-absorptive and liquid-retaining, and mainly absorbs and holds liquid excrement such as urine. The bulk fiber layer 4b absorbs and holds excreta containing solid components and liquid components such as soft stools. However, a part of the liquid component is absorbed and held in the absorbent core 4a. In this embodiment, the absorptive core 4a includes an absorptive core body 4a-1 and a core wrap 4a-2 that surrounds the absorptive core body 4a-1. The material of the core wrap 4a-2 is, for example, cotton paper.

Here, the bulk fiber layer 4b is a case where the porous plasmid sublayer of Patent Document 1 is used. Although it is effective for absorption and retention of liquid excreta that can be easily separated into solid components and liquid components, it is difficult to separate into solids. High viscosity liquid excreta, that is, high viscosity excretory fluids, are not necessarily considered effective. The reason is that if the porous plasmid sublayer absorbs high-viscosity fecal fluids, it is not only solid components but liquid components that are absorbed and maintained. Therefore, when the pressure is applied to the porous plasmid sublayer in this state from the outside, the internal pressure is high. Viscous fecal fluid may leak to the outside. In this case, the leaked high-viscosity fecal fluid is dyed out toward the surface sheet, thereby causing back osmosis.
Here, in the disposable diaper 1 of the present embodiment, the bulk fiber layer 4b of the absorbent body 4 is a layer containing a plurality of bulk fibers having a predetermined structure. Such a massive fiber layer 4b can appropriately absorb and hold the high-viscosity excretion fluid, and can appropriately suppress the internal high-viscosity excretion fluid from leaking to the outside even if pressure is applied from the outside. The high-viscosity fecal fluid may, for example, be the soft stool of a baby before being fed. This will be specifically described below.

FIG. 5 is a schematic diagram showing a configuration example of the bulk fiber layer 4b and the plurality of bulk fibers 40 in FIG. 4. Fig. 5 (a) shows a configuration example of the bulk fiber 40, and Fig. 5 (b) shows a configuration example of the bulk fiber layer 4b. The bulk fiber layer 4 b includes a plurality of bulk fibers 40. As shown in FIG. 5 (a), the bulk fiber 40 includes a plurality of fibers entangled together, and the whole is formed of the bulk fibers in a state of a three-dimensional space shape. The fiber density is high, and the pressure is high. A core portion 41 that is difficult to collapse; and a crimpable fiber that protrudes from the peripheral edge of the core portion 41 to the outside, and has a low fiber density and protrudes from the fiber portion 42 easily. Further, as shown in FIG. 5 (b), in the bulk fiber layer 4b, the adjacent bulk fibers 40 are in contact with each other through the protruding fiber portions 42 of the bulk fibers.

The disposable diaper 1 provided with the block fiber layer 4b can achieve the following effects.
In the bulk fiber layer 4b, the adjacent bulk fibers 40 are in contact with each other through the protruding fiber portion 42. The fibers of the protruding fiber portion 42 are rebounded and entangled with each other, and the adjacent core portions 41 are A gap (a gap between the core portions 41) caused by the fibers protruding from the fiber portion 42 is formed therebetween. At this time, the fibers protruding from the fiber portion 42 are made of crimpable fibers and have a relatively low fiber density. Therefore, when a pressure (load) is applied to the bulk fiber layer 4b, the fibers can be easily shrunk in response to the pressure. Therefore, since the protruding fiber portion 42 absorbs the pressure by contraction, the core portion 41 is hardly affected by the pressure, and deformation of the core portion 41 can be suppressed.
When pressure is applied to the bulk fiber layer 4b, the specific volume of the bulk fiber layer 4b decreases. However, in the aspect of reduction, first, when the pressure is small, the fiber density is low, and there are many voids, and it is easy to shrink. Therefore, the specific volume is mainly reduced by shrinking the protruding fiber portion 42. When the pressure is large, after the protruding fiber portion 42 is sufficiently contracted, the specific volume is further reduced mainly by shrinking the core portion 41 that has few voids and is difficult to contract. Therefore, the decrease in the specific volume of the bulk fiber layer 4b is performed in stages by the shrinkage of the protruding fiber portion 42 and the shrinkage of the core portion 41.

In addition, the disposable diaper 1 is used for absorbing high-viscosity excretion fluids which are difficult to separate into solid components and liquid components. The high-viscosity excretion fluid is captured and held by the voids in the protrusions and the voids in the protruding fiber portion 42. At this time, since the core portion 41 having the highest fiber density in the bulk fiber layer 4b has a high fiber density, when there is sufficient capacity, the high-viscosity excretion fluid once held in the protruding fiber portion 42 can be removed from The portion adjacent to the protruding fiber portion 42 is absorbed and held.
Furthermore, the disposable diaper 1 after use is such that when pressure is applied by a change in the posture of the wearer while the high-viscosity excretion is maintained, the crimpable fiber pair protruding the fiber portion 42 is used. It should shrink under pressure and become a buffer, and it can absorb this pressure. Therefore, the pressure can be hardly applied to the core portion 41. This makes it difficult to press the high-viscosity excretion liquid held in the space in the core portion 41 to the outside. Further, by shortening the distance between the bulk fibers 40 and increasing the fiber density of the voids protruding from the fiber portion 42, that is, by increasing the fiber density around the core portion 41, leakage from the core portion 41 can be suppressed. Thereby, it is possible to reduce the rate at which the high-viscosity excretion fluid once absorbed is returned to the surface sheet 2 side, that is, the surface return rate, and to increase the rate that remains in the bulk fiber layer 4b, that is, the retention rate.

Here, in the case where most of the high-viscosity excretion liquid is held in the gaps of the protruding fiber portion 42, the high-viscosity excretion liquid held in the gaps of the protruding fiber portion 42 is easily compressed to the outside by shrinking the protruding fiber portion 42. Out. However, since this high-viscosity excretion liquid moves below the protruding fiber portion 42 (side of the absorbent core 4a) by its own weight, it is in a state covered by the protruding fiber portion 42 above (surface sheet 2 side), that is, It is in a state covered by the top. As a result, even if the gap of the protruding fiber portion 42 is contracted, the lid (the protruding fiber portion 42 above) can be prevented from leaking the high-viscosity excretion liquid to the surface sheet 2 side. The high-viscosity excretion fluid that has nowhere to go can pass through the protruding fiber portion 42 of the bulk fiber 40 in the middle, and toward the core portion 41 and the protrusion of the bulk fiber 40 in the portion where the load is not applied (for example, the rupture of the buttocks). The space of the fiber part 42 moves. This makes it difficult to be pushed outward. In addition, for a liquid excrement having the property of being easily separated into a solid component and a liquid component, the solid component is mainly absorbed by the bulk fiber layer, and the liquid component is mainly absorbed by the absorbent core. In addition, for a liquid excrement having the property of being easily separated into a solid component and a liquid component, the solid component is mainly absorbed by the bulk fiber layer, and the liquid component is mainly absorbed by the absorbent core.

With such a disposable diaper 1, the absorption performance of high-viscosity excretion fluid can be maintained or improved, and the high-viscosity excretion fluid can be more inhibited from being dyed toward the surface sheet 2.

However, the fiber density of the core portion 41 is relatively high, and the fiber density of the protruding fiber portion 42 is relatively low, which can be confirmed by, for example, the following method. That is, the X-ray fluoroscopy device FLEX-M863 is used to perform a 360-degree scan of a block fiber or a block fiber layer. Specifically, each time the sample is rotated by 0.2 degrees, the X-ray perspective image is photographed, and 360 degrees, that is, 1,800 X-ray perspective images are obtained, and the 1800 X-ray perspective images obtained are combined into a 3D image. The areas of the same volume of the core portion 41 and the protruding fiber portion 42 are respectively extracted from the 3D image, and the approximate number of fibers is measured and compared from each extracted area.

Here, it is important that the bulk fiber layer 4b has the following configuration.
The specific volume of the bulk fiber layer 4b when a pressure (load) of 3 g / cm ² was applied to the bulk fiber layer 4 b was set as a reference specific volume (unit: cc / g). The specific volume of the bulk fiber layer 4b when a pressure greater than 3 g / cm ² is applied to the bulk fiber layer 4 b is set to a load specific volume (unit: cc / g). The ratio of the load specific volume to the reference specific volume is set to a specific volume ratio (unit: no dimension). And the ratio of the change of the specific volume ratio to the change of the pressure applied to the bulk fiber layer 4b is set as the change rate (unit: (g / cm ² ) ^-1 ). At that time, the block-like fiber layer 4b of the disposable diaper 1 which has the above-mentioned functions and effects has the following configuration. Change applied pressure (load) the bulk of the fibrous layer 4b is 3g / cm ² to 5g / cm ² was ^determined rate of change is the first change rate of -0.12 (g / cm ^{2) -1} above, -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 change of the pressure (load) applied to the bulk fiber layer 4b is 25 g / cm ² to 30 g / cm ² , that is, the second change rate is -0.02 (g / cm ² ) ^-1 or more, which is less than 0 (g / cm ² ) ^-1 . The second change rate is preferably -0.01 (g / cm ² ) ^-1 or more, and -0.005 (g / cm ² ) ^-1 or less. Here, a state in which a pressure of 3 g / cm ² is applied to the bulk fiber layer 4 b is a state in which almost no pressure is applied to the disposable diaper 1 in which the wearer is standing, and a pressure of 25 g / cm ² is applied to The state of the bulk fiber layer 4b is a state simulating a state in which a large pressure is applied to the disposable diaper 1 in which the wearer is sitting. And the change of the pressure (load) of 3g / cm ² to 5g / cm ² corresponds to the shrinkage of the protruding fiber portion 42, and the change of the pressure (load) of 25g / cm ² to 30g / cm ² corresponds to the shrinkage of the core portion 41 And change.

The first change rate is less than -0.12 (g / cm ² ) ^-1 because the specific volume ratio is caused by the shrinkage of the protruding fiber portion 42 in response to a change in pressure applied to the bulk fiber layer 4 b. The reduction is too large (there are many gaps in the protruding fiber portion 42 or the amount of fibers in the protruding fiber portion 42 is small, etc.), so that it becomes easy to release the retained high-viscosity excretion fluid. On the other hand, the first rate of change is more than -0.025 (g / cm ² ) ^-1 because the specific volume ratio is caused by the shrinkage of the protruding fiber portion 42 in response to the change in pressure applied to the bulk fiber layer 4 b. The reduction will be too small (there are fewer gaps in the protruding fiber portion 42 or the amount of fibers in the protruding fiber portion 42 is large, etc.), so it is difficult to sufficiently maintain the high-viscosity excretion fluid. The second rate of change is less than -0.02 (g / cm ² ) ^-1 , that is, when the absolute value exceeds 0.015, because the shrinkage of the core portion 41 due to a change in pressure applied to the bulk fiber layer 4 b occurs. The reduction of the specific volume ratio will be too large (the core 41 has a lot of voids, or the amount of fibers in the core 41 is small, etc.), so the core 41 is easily deformed, and the high-viscosity excretion liquid becomes easy to dye.

The specific volume of the bulk fiber layer 4b is appropriately set in accordance with the required absorption amount of the high-viscosity excretion fluid, and the like. In this embodiment, when the pressure (load) applied to the bulk fiber layer 4b is 3 g / cm ² , the specific volume of the bulk fiber layer 4 b is, for example, 50 to 90 cc / g, and the pressure (load) is 25 g / For cm ² , the specific volume is, for example, 20 to 35 cc / g. However, if the specific volume of the bulk fiber layer 4b is relatively small, the fiber density of the bulk fiber layer 4b will be relatively high, and the absorption amount of the high-viscosity fecal fluid will be relatively small. Release a relatively difficult tendency.

The sizes of the core portion 41 and the bulk fibers 40 are appropriately set in accordance with the required absorption amount of the high-viscosity excretion fluid, and the like. In this embodiment, the shapes of the core portion 41 and the block-shaped fibers 40 are block-like and not spherical, and the shape and thickness of the protruding fiber portion 42 covering the outer peripheral surface of the core portion 41 are not uniform. Here, in this embodiment, the core portion 41 and the bulk fibers 40 are regarded as balls, and the protruding fiber portion 42 is regarded as a layer having a uniform thickness covering the outer peripheral surface of the core portion 41. At that time, the average radius r of the core portion 41 is, for example, a range of 0.1 to 0.5 cm (the diameter 2r is, for example, a range of 0.2 to 1 cm). The average thickness d of the protruding fiber portion 42 is, for example, in a range of 0.2 to 0.6 cm. Therefore, the average radius (r + d) of the bulk fiber 40 is, for example, a range of 0.3 to 1.1 cm (the diameter 2 × (r + d) is a range of 0.6 to 2.2, for example). However, if the diameter of the core portion 41 is relatively large, the absorption amount of the high-viscosity excretory fluid that can be stably maintained will be relatively increased, but it tends to be easily affected by the body pressure of the wearer. When the thickness of the protruding fiber portion 42 is relatively large, the absorption amount of the high-viscosity excretory fluid that can be stably maintained is relatively reduced, but it tends to be hardly affected by the body pressure of the wearer.

In a preferred aspect of this 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 more preferably in the range of 0.7 to 1.5. That is, the average thickness d of the protruding fiber portion 42 on the surface of the core portion 41 in the bulk fiber 40 is 0.4 times or more, preferably 2 times or less, 0.7 times or more, and 1.5 times or less the average diameter 2r of the core portion 41. Better. In this way, when the average thickness d of the protruding fiber portion 42 is in the above-mentioned range, the high-viscosity excretion fluid can be more appropriately maintained in the gaps of the protruding fiber portion 42 and pressure is applied to the bulk fiber layer 4b. The space of the protruding fiber portion 42 can be more moderately contracted, and this pressure can be more appropriately absorbed. This makes it possible to prevent pressure from being applied to the core portion 41.
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 cannot be sufficiently ensured, and the pressure is easily applied to the core portion 41, and the high viscosity is excreted. The liquid becomes easy to be dyed from the core portion 41. When the average thickness d of the protruding fiber portion 42 exceeds twice the average diameter 2r of the core portion 41, in the state where most of the high-viscosity excretion fluid is maintained in the protruding fiber portion 42, the protruding fiber portion 42 is contracted and has a high viscosity The fecal fluid is easily stained from the protruding fiber portion 42.

The mass of each of the bulk fibers 40 and the number of the bulk fibers 40 per 1 cm ³ of the bulk fiber layer 4b are appropriately set in accordance with the required absorption amount of the high-viscosity excretion fluid and the like. In this embodiment, the mass of each of the bulk fibers is, for example, 0.5 to 8 mg / piece. The number of the bulk fibers 40 per 1 cm ³ of the bulk fiber layer 4 b (but in an unloaded state) is, for example, 2.5 to 30 fibers / cm ³ . However, if the mass of each of the bulk fibers 40 and the number of the bulk fibers 40 per 1 cm ³ of the bulk fiber layer 4b are relatively large, the absorption amount of the high-viscosity fecal fluid will be relatively large.

In a preferred aspect of this embodiment, the specific volume ratio when the pressure applied to the bulk fiber layer 4b is 25 g / cm ² is 0.2 or more, 0.7 or less, 0.3 or more, and 0.6 or less.
The specific volume ratio when the pressure is 25 g / cm ² is within this range. When pressure is applied to the bulk fiber layer 4 b, the voids of the protruding fiber portion 42 can be more appropriately contracted. Thereby, in the protruding fiber portion 42, the fiber density of the protruding fiber portion 42 is sufficiently increased, and it is possible to further suppress the high-viscosity excretion liquid in the voids of the protruding fiber portion 42 from being dyed to the outside. Moreover, in the core portion 41, since the protruding fiber portion 42 acts as a buffer and absorbs pressure more appropriately, it is more difficult to apply pressure to the core portion 41, and it is possible to further suppress high-viscosity excretion fluid in the voids of the core portion 41 from staining to the outside Out. Here, when the ratio of the load to the volume is less than 0.2, the shrinkage of the protruding fiber portion 42 caused by the pressure is excessively large, and the high-viscosity excretion liquid is mainly easy to be dyed from the protruding fiber portion 42. When the ratio of the load to the volume exceeds 0.7, the shrinkage of the protruding fiber portion 42 due to the pressure is too small, and the high-viscosity excretion liquid is mainly easily dyed from the core portion 41.

When the ratio of the voids between the core portions 41 in the bulk fiber layer 4b is set to the porosity, the porosity when the pressure applied to the bulk fiber layer 4b is 3 g / cm ² is set to the first porosity. The porosity when the pressure applied to the bulk fiber layer 4b was 25 g / cm ² was set to the second porosity. At that time, in a preferred aspect of this 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 50% or more, more preferably 80% or less, and the second porosity is 2% or more, and more preferably 50% or less.
The first porosity is in this range, that is, when the porosity is hardly applied to the bulk fiber layer 4b (3g / cm ² ) and the porosity is 40% to 80%, a sufficient core portion 41 can be ensured to have a high viscosity. The fecal fluid is captured, and sufficient protrusion of the fiber portion 42 can be ensured to cushion the pressure. When the second porosity is in this range, that is, when the porosity of the bulk fiber layer 4b (25 g / cm ² ) is 2% to 60% when pressure is applied, it is ensured that the fiber portion 42 is sufficiently protruding to have a high viscosity. The excretory fluid is maintained, and the protruding fiber portion 42 can be sufficiently contracted, so that the application of pressure to the core portion 41 can be suppressed. When the first porosity is less than 40%, the protruding fiber portion 42 cannot ensure a space that can shrink properly when the pressure increases, and when it exceeds 80%, the core portion 41 cannot ensure that the high-viscosity excretion liquid can be sufficiently absorbed. Gap. When the first porosity is less than 5%, a gap where the high-viscosity excretion liquid can be sufficiently maintained cannot be ensured in the protruding fiber portion 42, and when it exceeds 60%, a high-viscosity excretion liquid is maintained in the gap in the protruding fiber portion 42. Within is becoming difficult.

In other embodiments, at least a part of the surface sheet 2 may have a plurality of through holes (not shown) penetrating toward the bulk fiber layer 4b in the thickness direction T. The plurality of through-holes pass from one surface of the surface sheet 2 to the other surface, and not only a liquid component is permeable but also a solid-component-pervious hole. Therefore, the high-viscosity excretion liquid can penetrate the surface sheet 2 through a plurality of through holes. For a plurality of through-holes, the ratio of the sum of the cross-sectional areas of the through-holes to the area of the surface sheet 2, that is, the opening ratio, is preferably 5 to 90%. The diameter of the through hole is preferably smaller than the diameter of the bulk fibers 40 contained in the bulk fiber layer 4b, and the upper limit is preferably less than 1 cm. The lower limit is not particularly limited, and examples include 0.08 cm or more. The number of the through holes is preferably 0.3 to 30 / cm ² . In the case where the surface sheet 2 has a low basis weight (example: 8 to 20 g / m ² ), the surface sheet 2 can be referred to as a surface sheet 2 having a plurality of through holes because many voids exist.

The bulk fibers 40 contained in the bulk fiber layer 4b are preferably made of fibers having hydrophilic properties. This makes it possible to impart hydrophilicity to the bulk fiber layer 4b. Examples of the hydrophilic fiber include at least one of a hydrophilic fiber and a hydrophobic fiber that has been hydrophilized. Examples of the hydrophilic fibers include fibers produced from hydrophilic materials such as cotton and pulp. Examples of the hydrophobic fibers include polyester fibers and polyolefin fibers. Examples of the hydrophilic treatment include the use of surfactants and hydrophilic fibers. Agent treatment. The bulk fibers 40 are within a range capable of maintaining hydrophilicity, and may include hydrophobic fibers. Since the bulk fiber layer 4b is hydrophilic, excrement can be efficiently transmitted, absorbed, and held. In this embodiment, in a preferred aspect, the bulk fibers 40 are fiber balls. The appearance of a fiber ball is similar to that of a ball-shaped fiber. By forming the bulk fiber 40 from a fiber ball, the bulk fiber 40 and the bulk fiber layer 4b having the predetermined core portion 41 and the protruding fiber portion 42 can be easily formed.

The bulk fiber 40 is a case where a fiber ball is used. It may be manufactured by a known method, or a commercially available product may be used. Examples of the method for producing a fiber ball include a method of skeining fibers into granules (example: Japanese Patent Application Laid-Open No. 2016-94692), and a method of thermally fusing fibers or heat-shrinking to granulate ( Examples: Japanese Unexamined Patent Publication No. 2000-345457, Japanese Unexamined Patent Publication No. 7-39659, etc.), and a method for granulating with a bonding agent (examples: Japanese Unexamined Patent Publication No. 63-50373, Japanese Unexamined Patent Publication No. 11-105030 Bulletin). For example, Japanese Patent Application Laid-Open No. 2016-94692 discloses that a heat-fusible fiber and / or a fiber having no heat-welding property or difficult to be heat-sealed is placed in a conical trapezoidal container in which air rotates and flows through air The method of rotating a three-dimensional space to make a circular arc to form a fiber ball. Furthermore, Japanese Patent Application Laid-Open No. 2000-345457 discloses the use of a heat-adhesive composite fiber having a thermoplastic elastomer as a heat-adhesive component, and a polyester-based main fiber having high dry heat shrinkability, A method for manufacturing a fiber ball by heat shrinking. Furthermore, Japanese Unexamined Patent Publication No. 7-39659 discloses that a plurality of synthetic fiber crimped processing yarns are bundled and then bundled, and then cut, and thereafter, the melting point of the synthetic fiber crimped processing yarn is not satisfied. A method in which a heat treatment is performed at a temperature to produce a fiber ball by curling of the processed yarn. In each of these methods, for example, by controlling the forming conditions and the heat treatment conditions, the fiber ball-shaped fibers 40 having the core portion 41 and the protruding fiber portion 42 can be formed.

For the production of fiber balls, a commercially available fiber ball manufacturing device (example: granulation device, Ball Fibers Forming Machine, CMM1, manufactured by Masias, Inc.) can be used. The fiber ball produced by the fiber ball manufacturing device is, for example, a fiber ball obtained by forming a thermoplastic resin fiber (example: polyester fiber) into a fiber ball. When the thermoplastic resin fiber is formed into a fiber ball, a crimpable fiber is used as the fiber in the fiber ball. This can form a fiber ball in which the protruding fiber portion can be easily contracted when pressure is applied, and the protruding fiber portion can be easily extended when the pressure is dissipated. For example, by controlling the molding conditions and the like, a fiber ball-shaped fiber 40 having a core portion 41 and a protruding fiber portion 42 can be formed.

In a preferred aspect of this embodiment, the fibers of the core portion 41 and the fibers of the protruding fiber portion 42 in the bulk fiber 40 are the same. Therefore, since the fibers are continuously connected from the core portion 41 to the protruding fiber portion 42, it is easier to capture the high-viscosity excretion fluid from the protruding fiber portion 42 and guide it toward the core portion 41. At the same time, since the predetermined protruding fiber portion 42 and the core portion 41 can be more surely formed, it is possible to more reliably crush the core portion with higher fiber density, and it is possible to easily protrude the fiber with lower fiber density. Department crushed. Thereby, when pressure is applied to the bulk fiber layer, the voids of the protruding fiber portion are moderately contracted to become a buffer, and the pressure can be appropriately absorbed, thereby preventing the pressure from being applied to the core portion.

In a preferred aspect of this embodiment, the fibers constituting each of the plurality of block fibers 40 are not thermally fused to each other. Thereby, the fiber can be easily contracted and extended in response to the application and dissolution of pressure. In addition, when pressure is applied to the disposable diaper 1, the fibers of the protruding fiber portion 42 can be easily shrunk, which makes it more difficult to apply pressure to the core portion 41. In addition, when the gap between the protruding fiber portion 42 and the core portion 41 absorbs the high-viscosity fecal fluid and swells, the intersection of the fibers can be prevented from interfering with the swelling.

In addition, part or all of the fibers constituting each of the plurality of block fibers 40 may be joined. In this case, compression resistance or compression resilience can be imparted to the bulk fibers 40. The bonding method is, for example, a method of thermally fusing the fibers to each other, and examples thereof include a method of bonding the fibers to each other (bonding fiber, adhesive, etc.). This makes it possible to suppress a decrease in the specific volume (void ratio) of the bulk fiber layer 4b and the bulk fiber layer 4b accompanying it during use of the disposable diaper 1 (example: body pressure of the installer). Reduced absorption and retention performance.

It is preferable to apply an adhesive (example: a thermal fusion adhesive) to the interface between the bulk fiber layer 4b and the surface sheet 2 and / or the interface between the bulk fiber layer 4b and the absorbent core 4a. Thereby, the block-shaped fiber 40 contained in the block-shaped fiber layer 4b can be fixed. From the viewpoint of permeation of a liquid containing high-viscosity excretion, it is preferable that the adhesive is not applied to the entire interface, but is patterned by, for example, dots, spirals, and stripes. The application method of the adhesive is, for example, spiral continuous application, applicator application, curtain coater application, peak gun application, or the like. The application amount (basis weight) of the adhesive is, for example, 3 to 100 g / m ² .

In a preferred aspect of this embodiment, the basis weight of the adhesive between the bulk fiber layer 4b and the surface sheet 2 is lower than the basis weight of the adhesive between the bulk fiber layer 4b and the absorbent core 4a. That is, since the basis weight of the adhesive between the bulk fiber layer 4b and the surface sheet 2 is relatively small, the space of the bulk fiber layer 4b can be suppressed because the adhesive is difficult to use for the absorption and movement of high-viscosity excretion fluid State of affairs. Thereby, the massive fiber layer 4b can capture and hold a high-viscosity excretion liquid quickly. Moreover, since the basis weight of the adhesive between the bulky fiber layer 4b and the absorbent core 4a is relatively large, the contact area between the bulky fiber layer 4b and the absorbent core 4a is increased, and high-viscosity fecal fluids and other The water in the excrement moves toward the highly hydrophilic absorbent core 4a.

The thickness, basis weight, and the like of the bulk fiber layer 4b are appropriately adjusted according to the required absorption amount of the high-viscosity excretion fluid and the like. In this embodiment, the thickness of the bulk fiber layer 4b is, for example, 1 to 10 mm. The thicker the bulk fiber layer 4b is, the more the high-viscosity excretion liquid is absorbed, and the installation feeling tends to decrease. The basis weight of the bulk fiber layer 4b is, for example, 25 to 500 g / m ² . The more the bulk fiber layer 4b has a higher basis weight, the easier it is to hold a high-viscosity excretion fluid, but the mounting feeling tends to decrease. The thickness, basis weight, and the like of the bulk fiber layer 4b may be constant across the whole, or may be partially different.

Next, the manufacturing method of the disposable diaper 1 of this embodiment is demonstrated. FIG. 6 is a schematic diagram showing a configuration example of an absorber manufacturing apparatus according to an example.

The initial process is a process of forming the absorbent core body 411. As shown in FIG. 6, in the formation of the absorbent core body 411, a suction drum 110 that rotates in the conveying direction MD and an absorbent material supply unit 120 including a cover that covers the suction drum 110 are used. In the peripheral surface 111 of the suction drum 110, the recessed portion 112 of the type for absorbing the absorbent material is formed at a desired pitch in the circumferential direction. When the suction drum 110 is rotated to enter the recessed portion 112 toward the absorbent material supply portion 120, the suction portion 113 acts on the recessed portion 112, and the absorbent material supplied from the absorbent material supply portion 120 is vacuum-sucked toward the recessed portion 112. The absorbent material supplied from the absorbent material supply unit 120 includes a hydrophilic fiber F supplied from a pulverizer (not shown) and a high absorption supplied from the particle supply unit 121 at a predetermined mass mixing ratio. Copolymer P. In this manner, the absorptive core body 411 is formed in the recessed portion 112. The absorbent core body 411 is contained in a state where the hydrophilic fibers F and the superabsorbent copolymer P are mixed. The absorptive core body 411 formed in the recessed portion 112 is transferred to the lower-layer core wrap 91 in the conveyance direction MD by the action of the transfer and suction portion 150. A heat fusion adhesive is applied to the upper surface of the lower core wrap 91, and the absorbent core body 411 is bonded to the lower core wrap 91 by the heat fusion adhesive. The absorptive core body 411 transferred to the lower core wrap 91 is moved in the conveying direction MD.

The next process is a process of laminating the upper core package 92 on the absorbent core body 411 which is carried toward the conveyance direction MD. The thermal fusion adhesive is applied to the lower surface of the upper core package 92, and the absorbent core body 411 is joined to the upper core package 92 by the thermal fusion adhesive. In this way, a continuum of a laminate in which the upper core wrap 92, the absorbent core body 411, and the lower core wrap 91 are sequentially stacked is formed. This continuous body is cut into a predetermined shape by a pair of rollers 300 and 301 to form an absorbent core body 4a-1 and a core wrap 4a-2 covering the absorbent core body 4a-1. The absorptive core 4a.

The next process is a process of applying an adhesive to the absorbent core body 4a-1. The adhesive application device 302 is used for applying the adhesive. The adhesive application device 302 is, for example, applied by a spiral continuous application method, such as a spiral pattern, such as applying a thermal fusion adhesive.

The next process is a process of supplying a plurality of block fibers 40 on the adhesive application surface of the absorbent core 4a to form a block fiber layer 4b. For supplying the plurality of block fibers 40, a block fiber supply device 303 is used.

Through each of the processes described above, an absorbent core 4 having an absorbent core 4a and a bulk fiber layer 4b laminated on one surface of the absorbent core 4a is manufactured. The manufacturing of the disposable diaper 1 using the absorber 4 can be implemented by a well-known method.

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

FIG. 7 is a view showing another configuration example of the absorbent body of the disposable diaper 1. FIG. 7 (a) is a plan view of the absorbent body 4A, and FIG. 7 (b) is a VIIb-VIIb cross-sectional view of the absorbent body 4A. In the absorbent body 4A, the bulk fiber layer 4bA is a part of the area provided on the skin-side surface of the absorbent core 4a and applied to the middle portion 12 of the disposable diaper 1 after application. The portion where the block-like fiber layer 4bA is provided is, for example, a portion located closer to the back side portion 13 than the center of the area of the middle portion 12 of the disposable diaper 1 after application. The absorber 4A can suppress the expansion of the high-viscosity excretion fluid excreted from the wearer, and the high-viscosity excretion fluid is mainly absorbed by the bulk fiber layer 4bA.

FIG. 8 is a diagram showing another configuration example of the absorbent body of the disposable diaper 1. Fig. 8 (a) is a plan view of the absorbent body 4B, and Fig. 8 (b) is a VIIIb-VIIIb cross-sectional view of the absorbent body 4B. In the absorbent body 4B, the bulk fiber layer 4bB is a part of the area provided on the skin-side surface of the absorbent core 4a and applied to the middle portion 12 of the disposable diaper 1 after application. The portion provided with the bulk fiber layer 4bB is, for example, a portion extending in the longitudinal direction L of both ends in the width direction W in the area of the middle portion 12 of the disposable diaper 1 after application, The center portion is closer to the back side portion 13 side. The absorbent body 4B can prevent leakage of the high-viscosity excretion fluid excreted by the wearer more than one pair of leak-proof walls 7a, 7b. Therefore, the absorbent body 4B is particularly useful for diapers for infants of a relatively old age who are often in a lateral posture and whose feet are often opened and closed.

FIG. 9 is a diagram showing another configuration example of the absorbent body of the disposable diaper 1. Fig. 9 (a) is a plan view of the absorbent body 4C, and Fig. 9 (b) is a cross-sectional view taken along the line IXb-IXb of the absorbent body 4C. In the absorbent body 4C, the bulk fiber layer 4bC is a part of the area provided on the skin-side surface of the absorbent core 4a and applied to the back side portion 13 of the disposable diaper 1 after application. The absorber 4C can suppress the flow of the high-viscosity excretion fluid excreted from the wearer toward the back of the wearer. Therefore, the absorbent body 4C is particularly useful for diapers for infants of a relatively young age who are often in a supine posture.

[Example]

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

(I) Preparation of sample <Block fiber>
Bulk fibers are produced by the following method. Polyester fibers (fineness 7.4T, fiber length 32mm) that are hydrophilized on the surface of the fiber are processed into granulated cotton by an air-flow granulating device (Ball Fibers Forming Machine CMM1, manufactured by Masias), depending on the molding conditions. Then, massive fibers A to D were obtained.

＜ Surface sheet ＞
The surface sheet was produced by the following method. Core-sheath type composite fiber using polyethylene terephthalate (PET) as a core component and high-density polyethylene (HDPE) as a sheath component (core-sheath ratio 50:50 (cross-sectional area ratio), fineness 4.4 (dtex, fiber length: 51 mm), carding treatment was performed on those to which a hydrophilic oil agent was adhered, and a fiber coil (basic weight: 10 g / m ² ) was produced. This fiber coil was subjected to a ventilation bonding process, and a nonwoven fabric (thickness: 1.0 mm) was manufactured.

＜ Absorbent core ＞
The absorptive core was manufactured by the following method. The cotton pulp obtained by pulverizing the short fiber pulp (soft pulp) (manufactured by International Paper Co., Ltd .: Super Soft) and the superabsorbent copolymer (manufactured by Sumitomo Chemical Co., Ltd .: SA50) are dispersed uniformly. After mixing, the layers were laminated to produce a laminate having a length of 300 mm, a width of 120 mm, a basis weight of cotton pulp of 250 g / m ² ± 3%, and a basis weight of the super absorbent copolymer of 250 g / m ² ± 3%. body. The thus-manufactured laminate was held by two pieces of tissue paper coated with a thermal fusion adhesive on the surface on the side of the laminate, and then press-molded by a pressure device with a thickness of 2.5 mm.

<Manufacture of samples of Examples and Comparative Examples>
Samples of Examples 1 to 4 and Comparative Example 1 were produced by the following methods.
(1) Example 1: On the upper side of the central portion in the above-mentioned absorbent core, a plurality of block fibers A were laminated so that the basis weight became 100 g / m ² ± 3% in a region of length 120 mm × width 100 mm. And only in the part of the plurality of block fibers that are not adhered, the surface sheet to which the thermal fusion adhesive is applied is adhered to the upper surface of the absorbent core.
(2) Example 2: The same as Example 1 except that the bulk fiber A was changed to the bulk fiber B.
(3) Example 3: The same as Example 1 except that the bulk fiber A was changed to the bulk fiber C.
(4) Example 4: The same as Example 1 except that the bulk fiber A was changed to the bulk fiber D.
(5) Comparative Example 1: The same as Example 1 except that the bulk fiber A was changed into a cotton ball (manufactured by Suzuran Co., Ltd .: Suzuran cotton ball No. 3).

(II) Evaluation of samples
(II-1) Evaluation of bulk fibers First, regarding the bulk fibers of Examples 1 to 4 and Comparative Example 1, that is, the bulk fibers A to D and cotton balls, the average diameter of the core portion was 2r, The average diameter 2 × (r + d) and the average thickness d of the protruding fiber portions were obtained by the following methods.

<Average diameter of core 2r>
(i) Using a digital microscope VHX-2000 (Keans Co., Ltd.), the lens magnification is set to a magnification at which the bulk fibers of the measurement object can enter the screen (example: 20 to 200 times).
(ii) Set the image size to 1600 pixels (H) x 1200 pixels (V).
(iii) The mass fibers to be measured are assembled on the transmission measurement unit, and the image is photographed.
(iv) After saving the image and reading it again, select "Measure", "Automatic Area Measurement", "Brightness", and "Start Measurement".
(v) The binarization threshold is set to 0, and the extraction parameters are binarized by checking "dark", "hole burying", and "small particle removal".
(vi) Record the area of the extracted area automatically calculated as the projected area of the bulk fiber.
(vii) The above (iii) to (vi) are performed on 10 block fibers, and the projected area of the 10 block fibers is obtained. The average value Av of the projected areas of those 10 copies was obtained.
(vii) The diameter-converted value in the case where the average value Av of the obtained projected area is the area of a circle is obtained by (4 × Av / π) ^0.5 as the diameter 2r (approximate value) of the core portion 41.

<Average diameter of lump fibers 2 × (r + d)>
(i) Using a digital microscope VHX-2000 (Keans Co., Ltd.), the lens magnification is set to a magnification at which the bulk fibers of the measurement object can enter the screen (example: 20 to 200 times).
(ii) Set the image size to 1600 pixels (H) x 1200 pixels (V).
(iii) The mass fibers to be measured are assembled on the transmission measurement unit, and the image is photographed.
(iv) The image was stored and read out, and the longest length (long diameter) of the bulk fiber was measured.
(v) The longest length (short diameter) of the bulk fiber was measured under the condition of perpendicularly crossing the measurement line of the long diameter.
(vi) The above (iii) to (v) are performed on 10 block fibers, and the long and short diameters of the 10 block fibers are obtained. An average value r _{L of the} major axis and an average value r _{S of} the minor axis of those 10 portions were obtained.
(vii) Obtain the average value r _L of the major axis and the mean value r _S of the minor axis (r _L + r _S ) / 2, and use it as the diameter of the bulk fiber 2 × (r + d) (approximate value) ).

<Average thickness d of protruding fiber portion>
(i) Subtract the diameter 2r (approximate value) of the core portion 41 from the diameter 2 × (r + d) (approximate value) of the above-mentioned bulk fiber, multiply by 1/2, and multiply the thickness d of the protruding fiber portion 42 ( (Approximate).

＜ Result ＞
Examples of images taken when the average core diameter 2r, the average diameter of the bulk fibers 2 × (r + d), and the average thickness d of the protruding fiber portions are obtained, and an example of an image obtained by binarizing the image, such as Figure 10 shows. FIG. 10 is an optical microscope image of the bulk fibers 40 in an example of each of the samples of Examples 1 to 4 and Comparative Example 1, and an image of the binarized fibers. As shown in the figure, in each of the samples of Examples 1 to 4, the protruding fiber portions existed widely around the core portion, but in the sample of Comparative Example 1, the protruding fiber portions existed only slightly. The results of obtaining the average diameter 2r of the core portion and the average thicknesses d and d / 2r of the protruding fiber portion are shown in Table 1 below. The range of d / 2r was determined, with 0.4 to 2 being preferred, and 0.7 to 1.5 being more preferred.

(II-2) Evaluation of each sample of Examples 1 to 4 and Comparative Example 1 For each sample of Examples 1 to 4 and Comparative Example 1, the change rates of specific volume, specific volume ratio, and specific volume ratio were as follows Method.

＜ Specific volume ＞
The following measurements were performed on the bulk fibers A to D and cotton balls of Examples 1 to 4 and Comparative Example 1, respectively.
(i) Into a cylinder (section area: 18 cm ² ) with a diameter of 48 mm, a plurality of bulk fibers were uniformly charged in a total amount of 0.180 g (equivalent to 100 g / m ² ) to prepare a measurement sample. This measurement sample is a simulated bulk fiber layer 4b.
(ii) Thickness measuring device: The thickness of the measurement sample in the center portion of the cylinder was measured by a dial gauge gauge JB (manufactured by Ozaki Manufacturing Co., Ltd.). At this time, a load of 3 g / m ² was applied to the sample by the weight of the measurement portion of the thickness measuring device. Use this thickness as the reference thickness. The specific volume at this stage is the above-mentioned reference specific volume, and is calculated from the measured reference thickness by the following calculation formula.
Reference specific volume (cc / g) = π × {cylinder radius (cm)} ² × measured reference thickness (cm) / sample mass (0.180g)
(iii) Next, a predetermined pressure (load) was applied to the measurement portion of the thickness measuring device, and the thickness of the measurement sample was measured with a hammer of a predetermined mass placed on the top surface of the holding portion of the thickness measuring device. At this time, it is a state where a predetermined load is applied by the weight of the measuring part of the thickness measuring device and the weight. Let this thickness be the load thickness. The specific volume at this stage is the above-mentioned specific volume of load, and is calculated from the measured load thickness by the following calculation formula.

Load specific volume (cc / g) = π × {cylinder radius (cm)} ² × measured load thickness (cm) / sample mass (0.180g)

＜ Specific volume ratio ＞
Each load calculated by the above method, that is, the specific volume of the load in the pressure (load), is divided by the reference specific volume, and the specific volume ratio (without dimension) at each load is calculated. The specific volume ratio may be a value obtained by normalizing the specific volume in each load from the specific volume of the pressure (load) of 3 g / m ² .

＜ Change rate of specific volume ratio ＞
From the graph of the load specific volume and the pressure (load) calculated by the above method, the change ratio of the ratio of the change in specific volume ratio to the change in pressure (load) was calculated. For example, when the change in pressure (load) is the rate of change in specific volume ratio when the change is from 3 g / cm ² to 5 g / cm ² , it is calculated by the following formula.
(Change rate ((g / cm ² ) ^-1 )
= ((5g / cm ² specific volume ratio)-(3g / cm ² specific volume ratio)) /
{(5g / cm ² )-(3g / cm ² )}

In addition, for each of the samples of Examples 1 to 4, and Comparative Example 1, the mass of the bulk fibers, the number of the bulk fibers per unit volume, and the porosity between the cores of the bulk fiber layers were determined by the following method .

<Mass of mass fiber>
For each mass of the bulk fiber, a predetermined number, for example, the mass of the 50 bulk fiber is measured by an electronic balance and is calculated by dividing the number.

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

＜ Voids between cores ＞
The ratio of the voids between the plurality of cores in the bulk fiber layer, that is, the void ratio F1 between the cores, is calculated by the following formula.
F1 (%) = (1- (4/3) × π × r ³ × N) × 100
However, r is the radius of the core, and N is the number of block fibers per unit volume.

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

<Evaluation method of penetration time, surface return rate, and retention rate>
(i) For each of the samples of Examples 1 to 4 and Comparative Example 1 (including a bulk fiber layer including a surface sheet and a plurality of bulk fibers and an absorbent core), a 10-mesh metal was placed on the center portion. A 60 mm diameter cylinder is attached to the bottom of the screen.
(ii) An artificial soft stool 15g fine scale whose viscosity is adjusted to 2000 mPa · s, and injected into a cylinder through a syringe.
(iii) The artificial soft stool is injected at the same time that the stopwatch starts timing. The artificial soft stool is moved toward the sample through the wire mesh, and the time until the exposure of the wire mesh at the bottom of the cylinder is measured is taken as the penetration time. However, even if the wire mesh is not exposed even after 3 minutes, it is over.
(iv) Unclamp the cylinder 3 minutes after the injection of artificial soft stool. Place a 10 cm × 10 cm filter paper (manufactured by As_ONE Co., Ltd .: NO1 filter paper) on the sample, and further place it on the filter paper to 20 g / cm ² The load of the hammer was placed and left for 30 seconds.
(v) After 30 seconds, the mass of the filter paper is measured, the mass of the original filter paper is subtracted, and the return amount of artificial soft stool is calculated. The value of the obtained return amount was divided by the amount of artificial soft stool injection, and was used as the surface return rate.
(vi) Next, the surface sheet is peeled off, and a mass of fibrous layers (including artificial soft stool) in a circular range with a diameter of 85 mm centered on the cylinder is taken out and the mass is measured.
(vii) From the measured mass, in the range of 85 mm, the mass of the original blocky fiber layer (0.567 g) before absorbing artificial soft stool was subtracted, and the amount of artificial soft stool held by the blocky fiber layer was calculated. The value of the obtained retention amount was divided by the amount of artificial soft stool injection as the retention rate.

＜ Manual soft stool modulation method ＞
However, the modulation method of artificial soft stool is as follows.
First, an agent containing the following components in the following ratio was prepared. That is, the ion exchange water is set to 71.9% by mass, NaCl to 1.0% by mass, glycerol to 15.0% by mass, NaCMC to 2.0% by mass, and three tons of X-100 to 0.05%. %, Red 102 was 0.05% by mass, and powdered cellulose was 10.0% by mass. And the viscosity of the agent was adjusted to 2000 mPa · s by ion exchanged water as artificial soft stool.

Table 2 shows the results of the measurements performed in Examples 1 to 4 and Comparative Example 1, bulk fibers A to D, and cotton balls.

In addition, FIG. 11 is a graph showing the load (pressure and specific volume relationship) in the bulk fiber layer 4b in each sample of Examples 1 to 4 and Comparative Example 1. The horizontal axis is the load (pressure) (g / cm) ² ), the vertical axis is the specific volume (cc / g). The diamond (◇) is Example 1, the four corners (□) are Example 2, the triangle (△) is Example 3, and the circle (0) is Example 4, The reverse triangle (▽) is Comparative Example 1. In the samples of Examples 1 to 4, although the specific volume decreased sharply in the initial stage of the increase in the load (pressure), the increase in the load (pressure) was performed when the specific volume was increased. On the other hand, in the sample of Comparative Example 1, the load (pressure) was reduced by the same ratio as the comparison.

Fig. 12 is a graph showing the relationship between the load (pressure) and the specific volume ratio in the bulk fiber layer 4b 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 of the graph of FIG. 11 is normalized from the value of the specific volume of the load (pressure) of 3 g / cm ² . The horizontal axis is the load (pressure) (g / cm ² ), and the vertical axis is the specific volume ratio (no dimension). The diamond (◇) is Example 1, the square (□) is Example 2, the triangle (Δ) is Example 3, the circle (0) is Example 4, and the inverse triangle (▽) is Comparative Example 1. By normalization, the difference between the tendency of the graphs of Examples 1 to 4 and the tendency of the graphs of Comparative Example 1 is made clearer.

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

This is because in the samples of Examples 1 to 4, in the initial stage of the increase in the load (pressure), the specific volume was sharply reduced by the shrinkage of the protruding fiber portion, and the protruding fiber was made to increase as the load (pressure) increased. If the portion becomes difficult to shrink, the core portion shrinks and the reduction in specific volume is eased. On the other hand, in the sample of Comparative Example 1, since there was almost no protruding fiber portion, the ratio was reduced by a comparatively similar ratio from the initial stage of the increase in the load (pressure) until the core portion contracted. That is, the effects of the protruding fiber portions of Examples 1 to 4 were confirmed.

As shown in Table 1, in the samples of Examples 1 to 4, the surface return rate was 15% or less, and the retention rate was 50% or more. On the other hand, in the sample of the comparative example, the surface return rate was more than 20%, and the retention rate was less than 40%. From this, it turns out that the effect of the bulk fiber layer 4b of Examples 1-4 was confirmed. That is, the bulk fiber layers 4b of Examples 1 to 4 can maintain or improve the absorption performance of the high-viscosity excretion fluid, and can suppress the high-viscosity excretion fluid from being stained (back osmosis) to the surface sheet 2. .

In addition, from the graphs in Tables 1 and 11 and 12, the change rate of the 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 range) ^-1 preferably, the volume ratio of the rate of change of the ratio / cm ² change in the load (pressure) toward 25g / cm ² to 30g range ^{-0.02 ~ 0 (g / cm 2} ) -1 is preferred . When the load (pressure) is 25 g / cm ² , the specific volume ratio is 0.2 or more, and a range of 0.7 or less is preferable. When the load (pressure) is 3 g / cm ² , the porosity is 40% or more, and the range of 80% or less is preferred. When the load (pressure) is 25 g / cm ² , the porosity is 2% or more, and the range of 60% or less is more. good.

1‧‧‧ diapers

2‧‧‧ sheet

3‧‧‧ cover sheet

4‧‧‧ Absorber

4A‧‧‧ Absorber

4a‧‧‧ Absorbent core

4a-1‧‧‧ Absorbent core body

4a-2‧‧‧ core wrap

4b‧‧‧ massive fiber layer

4B‧‧‧ Absorber

4bA‧‧‧ Bulk fiber layer

4bB‧‧‧ Bulk fiber layer

4bC‧‧‧ Bulk fiber layer

4C‧‧‧ Absorber

6‧‧‧ cover sheet

6a‧‧‧ opening

7a, 7b‧‧‧Leakproof wall

7Ea, 7Eb‧‧‧ Elastomer

8‧‧‧ back sheet

9‧‧‧ elastomer

9a, 9b‧‧‧ elastomer

9c, 9d‧‧‧ elastomer

10‧‧‧ Absorptive body

11‧‧‧ ventral

11a, 11b‧‧‧ both ends

11e‧‧‧ tip

12‧‧‧ middle

12a, 12b‧‧‧ both sides

13‧‧‧back side

13a, 13b ‧‧‧ both ends

13e‧‧‧ tip

14a, 14b ‧‧‧ Junction

15g‧‧‧artificial soft stool

40‧‧‧ block fiber

41‧‧‧Core

42‧‧‧ protruding fiber

50‧‧‧ core-sheath ratio

91‧‧‧ Lower core wrap

92‧‧‧ Upper core wrap

110‧‧‧Attraction drum

111‧‧‧ weekly

112‧‧‧ Recess

113‧‧‧Attraction

120‧‧‧ Absorbent Material Supply Department

121‧‧‧Particle Supply Department

150‧‧‧ transfer and adsorption department

300, 301‧‧‧ roller

302‧‧‧Adhesive application device

303‧‧‧block fiber supply device

411‧‧‧ Absorbent core body

[FIG. 1] A perspective view showing a configuration example of the disposable diaper according to the embodiment.

[Fig. 2] A plan view showing the unfolded state of the disposable diaper of Fig. 1.

[Figure 3] An exploded perspective view of the disposable diaper of Figure 1.

[Fig. 4] Fig. 1 is a view showing a configuration example of an absorbent body of the disposable diaper of Fig. 1. [Fig.

[FIG. 5] A schematic diagram showing a configuration example of the bulk fibers and the bulk fiber layer of the absorbent body of FIG.

Fig. 6 is a schematic diagram showing a configuration example of an absorber manufacturing apparatus according to an example.

[FIG. 7] A view showing another configuration example of the absorbent body of the disposable diaper of FIG.

[FIG. 8] A view showing another configuration example of the absorbent body of the disposable diaper of FIG. 1.

[FIG. 9] A view showing another configuration example of the absorbent body of the disposable diaper of FIG. 1.

[Fig. 10] An optical microscope photograph and a binarized image of a bulk fiber of an absorber.

[Fig. 11] A graph showing the relationship between the load and the specific volume in the bulk fiber layer.

[Figure 12] A graph showing the relationship between the load and the specific volume ratio in the bulk fiber layer.

Claims (9)

An absorbent article includes a liquid-permeable surface sheet, a liquid-impermeable back sheet, and an absorbent body located between the surface sheet and the back sheet. The absorbent body includes: an absorbent core, And a bulk fiber layer including a plurality of bulk fibers on a surface on the surface sheet side of the absorbent core, and each of the plurality of bulk fibers includes: a bulk fiber, which has a high fiber density and is difficult to crush A core portion formed by crimping fibers protruding from the periphery of the core portion to the outside, the fiber portion having a low fiber density and easily crushed, and protruding fiber portions that are easily crushed; adjacent block fibers are passed through the protrusions When the fiber portion is in contact, the specific volume of the bulk fiber layer when a pressure of 3 g / cm ² is applied to the bulk fiber layer is set to a reference specific volume, and the specific volume is added to the bulk fiber layer to be more than 3 g / cm ^2. The specific volume of the bulk fiber layer under a large pressure is set to a specific volume of a load, a ratio of the specific volume of the load to the reference specific volume is set to a specific volume ratio, and a change in the specific volume ratio is A pressure variation applied to the bulk of the fibrous layer when the change ratio is set to a rate of change, is applied to the bulk fiber layer is the rate of change in pressure ^{from 2} to 5g / cm ² at 3g / cm of the first change is The rate is -0.12 (g / cm ² ) ^-1 or more and -0.025 (g / cm ² ) ^-1 or less. The change in the pressure applied to the bulk fiber layer is 25 g / cm ² to 30 g / cm ² . The change rate, that is, the second change rate is -0.02 (g / cm ² ) ^-1 or more, and less than 0 (g / cm ² ) ^-1 . For example, if the absorbent article in the scope of patent application is No. 1, The average thickness of the protruding fiber portion on the surface of the core portion in the bulk fiber is 0.4 times or more and 2 times or less the average diameter of the core portion. If the absorbent article in the scope of patent application No. 1 or 2, Among the bulk fibers, the fibers of the core portion and the fibers of the protruding fiber portion are the same. For example, in the absorbent article according to the first patent application range, the specific volume ratio when the pressure applied to the bulk fiber layer is 25 g / cm ² is 0.2 or more and 0.7 or less. For example, if the absorbent article in the scope of patent application is No. 1, The fibers constituting the plurality of block fibers are not thermally fused to each other. For example, if the ratio of the voids between the cores in the block fiber layer is set to the void ratio, the absorbent article according to the first patent application range is 3 g / cm. The first porosity at ² is 40% or more and 80% or less. The second porosity when the pressure applied to the bulk fiber layer is 25 g / cm ² is 2% or more and 60% or less. For example, if the absorbent article in the scope of patent application is No. 1, The basis weight of the adhesive between the bulk fiber layer and the surface sheet is lower than the basis weight of the adhesive between the bulk fiber layer and the absorbent core. For example, if the absorbent article in the scope of patent application is No. 1, At least a part of the surface sheet has a plurality of through holes penetrating in the thickness direction toward the bulk fiber layer. For example, if the absorbent article in the scope of patent application is No. 1, The bulk fibers are fiber balls.