CN111386097B

CN111386097B - Absorbent article

Info

Publication number: CN111386097B
Application number: CN201880075274.3A
Authority: CN
Inventors: 山口正史; 合田裕树
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 2017-12-26
Filing date: 2018-10-19
Publication date: 2021-06-18
Anticipated expiration: 2038-10-19
Also published as: JP6667495B2; CN111386097A; JP2019115378A; TW201927268A; WO2019130751A1

Abstract

The absorption of the high-viscosity excreta liquid is maintained and improved, and the exudation of the high-viscosity excreta liquid to the surface sheet is suppressed. An absorbent body (4) of an absorbent article (1) is provided with an absorbent core (4a) and a block fiber layer (4b) containing a plurality of block fibers (40). The block fibers include a core portion (41) having a high fiber density and being hard to crush, and a protruding fiber portion (42) protruding outward from the core portion and having a low fiber density and being easy to crush. Will apply 3g/cm²The specific volume of the blocky fiber layer under pressure is used as a reference specific volume, and the applied specific volume exceeds 3g/cm²The specific volume of the bulk fiber layer at the pressure of (3) is defined as a specific volume under load, the ratio of the specific volume under load to a reference specific volume is defined as a specific volume ratio, and the ratio of the change in the specific volume ratio to the change in the pressure applied to the bulk fiber layer is defined as a rate of change. 3 to 5g/cm²The rate of change of (2) under pressure change is-0.12 to-0.025 (g/cm)²)^‑1，25～30g/cm²The rate of change under pressure change is-0.02 to 0 (g/cm)²)^‑1。

Description

Absorbent article

Technical Field

The present invention relates to an absorbent article.

Background

Absorbent articles that absorb liquid excreta having high viscosity are known. For example, patent document 1 discloses an absorbent article including a liquid-permeable front sheet, a liquid-impermeable back sheet, and an absorbent body located between the front sheet and the back sheet, the absorbent body including an absorbent core and a porous particle layer located on the front sheet side of the absorbent core. Examples of the porous particles of the porous particle layer include fiber spheres and porous cellulose particles. According to patent document 1, liquid excrement with high viscosity excreted into the top sheet of the absorbent article diffuses into the porous particle layer and temporarily accumulates in the porous particle layer. At this time, the voids between the porous particles and the voids in the porous particles function as a flow path for the liquid excrement. This allows the liquid excrement to rapidly diffuse in the porous particle layer and to be efficiently transferred to the absorbent body. However, among the components of the liquid excrement, moisture is easily transferred from the porous particle layer to the absorbent body, but solid components such as fibers are easily captured and held by the porous particle layer. As a result, the liquid excrement (mainly solid content) remaining in the porous particle layer slows down the movement as a fluid. This can prevent liquid excrement from seeping out (rewetting) from the porous particle layer to the liquid-permeable top sheet when pressure is applied to the absorbent article.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication (JP 2015) 188709

Disclosure of Invention

Problems to be solved by the invention

Patent document 1 describes that a high-viscosity liquid excrement has a property of being easily separated into a solid component and a liquid component. However, there are cases where a high-viscosity liquid excrement has properties that make it difficult to separate into a solid component and a liquid component. When a high-viscosity liquid excreta (hereinafter, also referred to as "high-viscosity excreta") having a property of being difficult to separate into a solid component and a liquid component is excreted into a top sheet of an absorbent article, not only the solid component but also the liquid component of the high-viscosity excreta can be captured and held by the voids between the porous particles and the voids within the porous particles. When pressure is applied from the outside to the absorbent article holding such a high-viscosity excreta liquid, the porous particles are compressed, the volume of the voids in the porous particles decreases, and the high-viscosity excreta liquid in the voids may leak to the outside of the porous particle layer. In addition, since there is no obstacle that impedes movement in the gaps between the porous particles, there is a possibility that the high-viscosity excreta liquid in the gaps may leak to the outside of the porous particle layer. Then, the leaked high-viscosity excreta liquid seeps out to the surface sheet, and rewetting occurs.

Accordingly, an object of the present invention is to provide an absorbent article capable of suppressing the leakage (rewet) of a high-viscosity excreta liquid to a topsheet while maintaining or improving the absorption performance for the high-viscosity excreta liquid.

Means for solving the problems

An absorbent article according to the present invention is an absorbent article including a liquid-permeable front sheet, a liquid-impermeable back sheet, and an absorbent body located between the front sheet and the back sheet, wherein the absorbent body includes: an absorbent core; and a block fiber layer that is located on the surface sheet side of the absorbent core and that includes a plurality of block fibers each including: a core part formed by massive fibers, wherein the fibers have high density and are difficult to flatten; and protruding fiber parts formed of crimpable fibers protruding outward from the peripheral edge of the core part, having a low fiber density and being easily flattened, wherein adjacent block fibers are in contact with each other via the protruding fiber parts, and 3g/cm is applied to the block fiber layers²The specific volume of the blocky fiber layer is used as a reference specific volume when the pressure is applied, and more than 3g/cm is applied to the blocky fiber layer²When the specific volume of the bulk fiber layer at the pressure of (3) is regarded as a specific load volume, the ratio of the specific load volume to the reference specific volume is regarded as a specific volume ratio, and the ratio of the change in the specific volume ratio to the change in the pressure applied to the bulk fiber layer is regarded as a change rate, the change in the pressure applied to the bulk fiber layer is 3g/cm²～5g/cm²The first rate of change is-0.12 (g/cm)²)^-1Above and-0.025 (g/cm)²)^-1Hereinafter, the change of the pressure applied to the block fiber layer was 25g/cm²～30g/cm²The second rate of change is-0.02 (g/cm)²)^-1Above and less than 0 (g/cm)²)^-1。

In the absorbent article of the present invention, in the block fiber layer, the adjacent block fibers are in contact with each other via the protruding fiber portions, and the fibers of the protruding fiber portions repel each other and intertwine with each other, thereby forming a void (a void between the core portions) formed by the fibers of the protruding fiber portions between the adjacent core portions. In this case, since the fibers of the protruding fiber portions are formed of fibers having crimpability and have a relatively low fiber density, when pressure (load) is applied to the bulk fiber layer, the fibers can be easily shrunk by the pressure. Therefore, since the protruding fiber portion contracts and absorbs the pressure, the influence of the pressure can be made less likely to be exerted on the core portion, and the 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, as a way of reducing this, first, when the pressure is small, the protruding fiber portion having many voids and being likely to shrink mainly shrinks, thereby reducing the specific volume. When the pressure is high, the core portion, which has small voids and is difficult to contract, mainly contracts after the contraction of the protruding fiber portion sufficiently progresses, and thus the specific volume further decreases. Therefore, the reduction in the specific volume of the bulk fiber layer causes the shrinkage of the protruding fiber portions and the shrinkage of the core portion to be performed in stages. In the absorbent article, the pressure change applied to the block fiber layer is 3g/cm²～5g/cm²The first rate of change was-0.12 (g/cm)²)^-1Above and-0.025 (g/cm)²)^-1Hereinafter, the change of the pressure applied to the bulk fiber layer was 25g/cm²～30g/cm²The second rate of change is-0.02 (g/cm)²)^-1Above and less than 0 (g/cm)²)^-1. However, a bulk fiber layer was applied at 3g/cm²The pressure state of (2) simulates a state in which almost no pressure is applied to the absorbent article in which the wearer stands, and 25g/cm is applied to the bulk fiber layer²The state of pressure of (a) simulates a state in which a large pressure is applied to an absorbent article in which a wearer is sitting. And, 3g/cm²～5g/cm²The change in pressure (load) of (2) corresponds to the change in shrinkage of the projected fiber part, 25g/cm²～30g/cm²The change in pressure (load) of (c) corresponds to the change in contraction of the core.

Such an absorbent article can absorb a high-viscosity liquid excreta, which is a high-viscosity liquid excreta having a property that it is difficult to separate into a solid component and a liquid component, and can replenish and retain the high-viscosity liquid excreta in the voids in the core portion of the block fibers and the voids in the protruding fiber portions in the block fiber layer. In this case, since the core portion having the highest fiber density among the block fiber layers has a high fiber density, the high-viscosity excreta liquid temporarily held by the protruding fiber portions can be absorbed and held from the portions adjacent to the protruding fiber portions when there is a margin in capacity. When pressure is applied due to a change in the posture of the wearer's body while such an absorbent article is holding a highly viscous excretory fluid, the crimpable fibers of the protruding fiber portions contract according to the pressure to serve as a cushioning material, thereby absorbing the pressure. Therefore, the pressure can be made to be hardly applied to the core. This makes it possible to prevent the high-viscosity waste liquid held in the void in the core from being pushed out to the outside. Further, the distance between the block fibers is reduced, and the fiber density of the voids of the protruding fiber portions is increased, that is, the fiber density around the core portion is increased, thereby suppressing leakage from the core portion. Here, when a large amount of high-viscosity excretory fluid is held in the gaps of the protruding fiber portions, the high-viscosity excretory fluid held in the gaps of the protruding fiber portions is easily pushed out to the outside by the shrinkage of the protruding fiber portions. However, since the high-viscosity excreta liquid moves downward (toward the absorbent member) of the protruding fiber section by its own weight, the excreta liquid is covered with the protruding fiber section above (toward the topsheet), that is, covered with the top. As a result, even if the void of the protruding fiber portion shrinks, the protruding fiber portion (cover) above can suppress leakage of the high-viscosity excreta liquid to the surface sheet side. Further, the high-viscosity excretory fluid no longer present at the cut portion can move to the core portion of the block fiber or the void of the protruding fiber portion at a portion to which no load is applied (for example, a cleft of the hip) via the protruding fiber portion of the block fiber in the middle. This makes it difficult to extrude the liquid to the outside. With such an absorbent article, the liquid excreta can be further inhibited from exuding to the topsheet while maintaining or improving the absorption performance for high-viscosity excreta. In addition, in the case of a liquid excrement having a property of being easily separated into a solid component and a liquid component, the solid component can be mainly absorbed by the bulk fiber layer, and the liquid component can be mainly absorbed by the absorbent core.

However, at the first rate of change, the rate of change is less than-0.12 (g/cm)²)^-1That is, when the absolute value exceeds 0.12, the held high-viscosity excretory fluid is easily discharged because the decrease in the specific volume ratio due to the shrinkage of the protruding fiber portions with respect to the change in the pressure applied to the bulk fiber layer is excessively large (the number of voids in the protruding fiber portions is large, the fiber amount of the protruding fiber portions is small, or the like). On the other hand, the first change rate exceeds-0.025 (g/cm)²)^-1That is, when the absolute value is less than 0.025, the specific volume ratio due to shrinkage of the protruding fiber portions with respect to a change in pressure applied to the bulk fiber layer is too small (the number of voids in the protruding fiber portions is small, the fiber amount of the protruding fiber portions is large, or the like), and thus it is difficult to sufficiently maintain the high-viscosity excretory fluid. In addition, the rate of change at 2 nd was less than-0.02 (g/cm)²)^-1That is, when the absolute value exceeds 0.015, the specific volume ratio due to the shrinkage of the core portion against the change in the pressure applied to the bulk fiber layer is excessively decreased (the number of voids in the core portion is large, the fiber amount in the core portion is small, or the like), so that the core portion is easily deformed and the high-viscosity excretory fluid is easily exuded.

A second aspect of the absorbent article according to the present invention may be the absorbent article according to the first aspect, wherein an average thickness of the protruding fiber parts on the surface of the core part in the block fibers is 0.4 times or more and 2 times or less an average diameter of the core part.

In the absorbent article, the average thickness of the protruding fiber sections is 0.4 times or more and 2 times or less the average diameter of the core section. When the average thickness of the protruding fiber portions is within this range, the high-viscosity excretory fluid can be appropriately retained in the voids of the protruding fiber portions, and when pressure is applied to the bulk fiber layer, the voids of the protruding fiber portions appropriately contract to become a cushioning material, and this pressure can be appropriately absorbed, whereby the pressure can be further prevented from being applied to the core portion. In this case, when the average thickness of the protruding fiber portions is less than 0.4 times the average diameter of the core portion, a sufficient space for the protruding fiber portions cannot be secured, pressure is easily applied to the core portion, and the high-viscosity excretory fluid is easily exuded from the core portion. When the average thickness of the protruding fiber part is more than 2 times the average diameter of the core part, the protruding fiber part shrinks in a state where a large amount of high-viscosity excreta liquid is retained in the protruding fiber part, and the high-viscosity excreta liquid easily seeps out from the protruding fiber part.

The third aspect of the absorbent article according to the present invention may be the absorbent article according to the first or second aspect, wherein the fibers of the core portion of the block fibers are the same as the fibers of the protruding fiber portions.

In the present absorbent article, the fibers of the core portion are the same as the fibers of the protruding fiber portions. Accordingly, the fibers are continuously connected from the core portion to the protruding fiber portions, and thus the high-viscosity excreta liquid can be more easily replenished and guided to the core portion by the protruding fiber portions. At the same time, since the predetermined protruding fiber portions and the core portions can be formed more reliably, the core portions having a high fiber density can be made more difficult to crush more reliably, and the protruding fiber portions having a low fiber density can be made easier to crush. Thus, when pressure is applied to the block-shaped fiber layer, the voids of the protruding fiber portions are appropriately contracted to serve as a cushion member, and the pressure can be appropriately absorbed, whereby the pressure can be further prevented from being applied to the core portion.

An absorbent article according to a fourth aspect of the present invention may be the absorbent article according to any one of the first to third aspects, wherein the pressure applied to the bulk fiber layer is 25g/cm²The specific volume ratio is 0.2 or more and 0.7 or less.

In the absorbent article, 25g/cm²The specific volume ratio under pressure is 0.2 to 0.7. When the specific volume ratio is within this range, the voids of the protruding fiber portions can be appropriately contracted when pressure is applied to the bulk fiber layer. Therefore, the fiber density in the protruding fiber part becomes high, and the high viscosity rows in the voids of the protruding fiber part can be suppressedThe leakage liquid oozes to the outside. In addition, in the core portion, since the protruding fiber portion serves as a cushion material and appropriately absorbs pressure, pressure is less likely to be applied to the core portion, and leakage of high-viscosity excreta liquid in the void of the core portion to the outside can be suppressed. In this case, when the specific load volume ratio is less than 0.2, the protruding fiber portion shrinks too much due to the pressure, and the high-viscosity excrement is likely to mainly ooze out of the protruding fiber portion. When the ratio of the specific load capacity exceeds 0.7, the protruding fiber portions are too small in shrinkage due to pressure, and the high-viscosity excrement is likely to mainly seep out of the core portion.

A fifth aspect of the absorbent article according to the present invention may be the absorbent article according to any one of the first to fourth aspects, wherein fibers constituting each of the plurality of block fibers are not thermally welded to each other.

In the absorbent article of the present invention, since the fibers of the block fibers are not thermally welded to each other, when pressure is applied to the absorbent article, the fibers of the protruding fiber portions can be easily contracted, and further pressure can be prevented from being applied to the core portion. Further, when the voids of the protruding fiber portions and the voids between the core portions absorb high-viscosity excrement and swell, the intersections between the fibers can be prevented from interfering with the swelling.

An absorbent article according to a sixth aspect of the present invention may be the absorbent article according to any one of the first to fifth aspects, wherein when a ratio of voids between the core portions in the block fiber layer is defined as a void ratio, a pressure applied to the block fiber layer is 3g/cm²The first porosity is 40% to 80%, and the pressure applied to the block fiber layer is 25g/cm²The second porosity in the case of (3) is 2% or more and 60% or less.

In the absorbent article, the first porosity of the block fiber layer is 40% to 80%, and the second porosity is 2% to 60%. Since little pressure is applied to the bulk fiber layer (3 g/cm)²) The void ratio of (a) is 40% to 80%, and therefore a sufficient core portion for replenishing the high-viscosity excreta liquid can be secured, and a sufficient protruding fiber portion for cushioning the pressure can be secured. In addition, toWhen the block fiber layer is applied with pressure (25 g/cm)²) The void ratio of (2%) to (60%) ensures sufficient protruding fiber portions for holding a high-viscosity excretory fluid, and the protruding fiber portions sufficiently contract to suppress the application of pressure to the core portion. Here, 3g/cm of the block fiber layer was formed²If the void ratio under pressure is less than 40%, voids that can be appropriately contracted when the pressure is increased cannot be secured in the protruding fiber portions, and if it exceeds 80%, voids that can sufficiently absorb high-viscosity excreta liquid cannot be secured in the core portion. In addition, the fiber layer was formed at 25g/cm in the bulk²If the void ratio under pressure is less than 2%, it is not possible to secure a sufficient void for holding the high-viscosity excreta liquid in the protruding fiber part, and if it exceeds 60%, it is difficult to hold the high-viscosity excreta liquid in the void of the protruding fiber part.

A seventh aspect of the absorbent article according to the present invention may be the absorbent article according to any one of the first to sixth aspects, wherein a basis weight of the adhesive between the block fiber layer and the top sheet is lower than a basis weight of the adhesive between the block fiber layer and the absorbent core.

In the absorbent article, the basis weight of the adhesive (exemplified by a hot melt adhesive) between the bulk fiber layer and the top sheet is lower than the basis weight of the adhesive between the bulk fiber layer and the absorbent core. Therefore, the space of the block fiber layer can be prevented from being unusable for absorption and transfer of the high-viscosity excretory fluid by the adhesive. Therefore, the massive fiber layer can quickly replenish and maintain the high-viscosity excretion liquid. Further, since the basis weight of the adhesive between the block fiber layer and the absorbent core is relatively large, the contact area between the block fiber layer and the absorbent core increases, and the moisture of the high-viscosity excreta liquid can be easily transferred to the highly hydrophilic absorbent core.

An eighth aspect of the absorbent article according to the present invention may be the absorbent article according to any one of the first to seventh aspects, wherein at least a part of the top sheet has a plurality of through-holes penetrating in a thickness direction toward the bulk fiber layer.

In the absorbent article of the present invention, the topsheet does not prevent permeation of the high-viscosity excreta liquid, and therefore, the high-viscosity excreta liquid can be transferred to the bulk fiber layer more quickly. The plurality of through-holes include not only through-holes formed as holes but also gaps between fibers of a sheet having a small basis weight of the surface sheet and having open through-holes.

An absorbent article according to a ninth aspect of the present invention may be the absorbent article according to any one of the first to eighth aspects, wherein the bulk fibers are fiber balls.

In the present absorbent article, since the bulk fibers are formed from the fiber spheres, the bulk fibers and the bulk fiber layer having the predetermined core portion and the protruding fiber portions can be easily formed.

Effects of the invention

According to the present invention, an absorbent article capable of suppressing the exudation (rewet) of a high-viscosity excreta liquid to a topsheet while maintaining or improving the absorption performance of the high-viscosity excreta liquid can be provided.

Drawings

Fig. 1 is a perspective view showing a structural example of a disposable diaper according to an embodiment.

Fig. 2 is a plan view showing a state where the disposable diaper of fig. 1 is unfolded.

Fig. 3 is an exploded perspective view of the disposable diaper of fig. 1.

Fig. 4 is a diagram showing a structural example of an absorber of the disposable diaper of fig. 1.

Fig. 5 is a schematic view showing an example of the structure of the block fibers and the block fiber layer of the absorbent body of fig. 4.

Fig. 6 is a schematic diagram showing a configuration example of the apparatus for manufacturing an absorbent body according to the embodiment.

Fig. 7 is a view showing another configuration example of the absorbent body of the disposable diaper of fig. 1.

Fig. 8 is a view showing still another configuration example of the absorbent body of the disposable diaper of fig. 1.

Fig. 9 is a view showing still another configuration example of the absorbent body of the disposable diaper of fig. 1.

Fig. 10 is an optical microscope photograph and a binarized image of bulk fibers of the absorber.

Fig. 11 is a graph showing a relationship between a load and a specific volume in a bulk fiber layer.

Fig. 12 is a graph showing a relationship between a load and a specific volume ratio in a bulk fiber layer.

Detailed Description

Hereinafter, the absorbent article of the embodiment will be described with reference to a pants-type disposable diaper (hereinafter, also simply referred to as "disposable diaper") 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 tape-type disposable diapers, urine pads, feces pads, and sanitary napkins.

First, the disposable diaper 1 of the present embodiment will be explained.

Fig. 1 to 3 are views showing a configuration example of a disposable diaper 1 according to the present embodiment. Fig. 1 is a perspective view showing a state when the disposable diaper 1 is used, fig. 2 is a plan view showing a state where the disposable diaper 1 is unfolded, and fig. 3 is a perspective view showing a state where the disposable diaper 1 is exploded. The disposable diaper 1 has a longitudinal direction L, a width direction W, and a thickness direction T orthogonal to each other in the state shown in fig. 2 and 3, and has a longitudinal center line CL passing through the center of the width direction W and extending in the longitudinal direction L, and a width center line CW passing through the center of the length direction L and extending in the width direction W. The direction toward the longitudinal center line CL and the direction away from the longitudinal center line CL are referred to as the inner direction and the outer direction in the width direction W, respectively. The direction toward the width direction center line CW and the direction away from the width direction center line CW are referred to as the inner direction and the outer direction in the longitudinal direction L, respectively. The disposable diaper 1 placed on a plane including the longitudinal direction L and the width direction W as viewed from above in the thickness direction T is referred to as "planar shape", and the shape grasped from the planar shape is referred to as "planar shape". The "skin side" and the "non-skin side" respectively refer to a side relatively close to the skin surface of the wearer and a side relatively distant from the skin surface in the thickness direction T of the disposable diaper 1 when the disposable diaper 1 is worn. These directions and the like are also applicable to the respective materials constituting the disposable diaper 1.

The disposable diaper 1 includes a front side portion 11, a back side portion 13, and an intermediate portion 12 between the front side portion 11 and the back side portion 13. The abdomen-side portion 11 is a portion of the disposable diaper 1 that abuts against the abdomen of the wearer. The intermediate portion 12 is a portion of the disposable diaper 1 that abuts the crotch of the wearer. The back side portion 13 is a portion of the disposable diaper 1 which abuts against the buttocks and/or the back of the wearer. Both ends 11a, 11b in the width direction W of the front side portion 11 and both

ends

13a, 13b in the width direction W of the back side portion 13 are joined to each other by a pair of joining

portions

14a, 14b in a state of being overlapped in the thickness direction T along the longitudinal direction L. In the disposable diaper 1, the waist opening WO is formed by the end portion 11e of the stomach-side portion 11 opposite to the intermediate portion 12 in the longitudinal direction L and the end portion 13e of the back-side portion 13 opposite to the intermediate portion 12 in the longitudinal direction L. In the disposable diaper 1, a pair of leg openings LO, LO are formed on both

side portions

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

The disposable diaper 1 includes an absorbent main body 10 for absorbing and retaining excrement, and a cover sheet 3 and a cover sheet 6 for retaining the absorbent main body 10 from the non-skin side and the skin side. The cover sheet 3 and the cover sheet cover both sides in the thickness direction T of the absorbent 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, a substantially rounded rectangular (or oval or elliptical) opening 6a is provided in substantially the center in the width direction W and the longitudinal direction L so as to expose the skin-side surface of the absorbent body 10, and absorption of excrement is smoothly performed. The absorbent main body 10 includes a front sheet 2 having liquid permeability, a back sheet 8 having liquid impermeability, and an absorbent body 4 having liquid absorbability and liquid retentivity, which is positioned between the front sheet 2 and the back sheet 8. The absorbent body 4 has a structure in which an absorbent core 4a located on the non-skin side and a block fiber layer 4b located on the skin side are laminated in the thickness direction T.

As a surface sheet 2, backAs materials of the topsheet 8, the absorbent core 4a of the absorbent body 4, the cover sheet 3, and the cover sheet 6, known materials that can be generally used in the disposable diaper 1 can be used. That is, examples of the material of the top sheet 2 include a liquid-permeable nonwoven fabric, a synthetic resin film having liquid-permeable holes formed therein, and a composite sheet thereof. Examples of the material of the nonwoven fabric include natural fibers, regenerated fibers, inorganic fibers, and synthetic resin fibers. The basis weight of the surface sheet 2 is, for example, 2 to 100g/m²Preferably 5 to 50g/m from the viewpoint of easy permeation of a high-viscosity excreta liquid²More preferably 8 to 20g/m². Examples of the back sheet 8 include a liquid-impermeable nonwoven fabric, a synthetic resin film, a composite sheet thereof, and an SMS nonwoven fabric. Examples of the material of the absorbent core 4a of the absorbent body 4 include hydrophilic fibers such as pulp fibers and synthetic fibers, and Super Absorbent Polymers (SAP). The basis weight of the fibers of the absorbent core 4a is, for example, 50 to 1000g/m²The basis weight of the super absorbent polymer is, for example, 10 to 500g/m². The block fiber layer 4b of the absorbent body 4 will be described later. As a material of the cover sheet 3, for example, the same material as the surface sheet 2 can be used. As the material of the cover sheet 6, for example, the same material as the back sheet 8 can be used. The absorbent main body 10, the cover sheet 3, and the cover sheet 6 are bonded to each other with an adhesive, and the absorbent body 4, the topsheet 2, and the backsheet 8 are bonded to each other with an adhesive. The adhesive can be a known material such as a hot-melt adhesive.

The disposable diaper 1 may include a pair of liquid-impermeable

leakage preventing walls

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

leakage preventing walls

7a and 7b extend in the longitudinal direction L on both sides in the width direction W of the skin-side surface of the topsheet 2, and are spaced apart from each other in the width direction W. The outer portions of the pair of

leakage preventing walls

7a and 7b in the width direction W are fixed to the top sheet 2 by thermal welding or the like to form fixed ends, and the inner ends in the width direction W are free ends to form stretchable gathers. A plurality of elastic bodies 7Ea, 7Eb such as rubber threads extending in the longitudinal direction L are disposed near the free ends of the pair of

leakage preventing walls

7a, 7b, respectively. The

elastic bodies

9a and 9b extend in the width direction W between the cover sheet 3 and the cover sheet 6 in the ventral portion 11 and the dorsal portion 13, respectively, and are arranged and sandwiched with a space in the longitudinal direction L. The

elastic bodies

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

elastic bodies

9c and 9d are continuously arranged along the longitudinal direction L at both ends in the width direction W of the ventral portion 11 and the dorsal portion 13 of the intermediate portion 12, and along the width direction W at the central portion of the intermediate portion 12. The

elastic bodies

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

Next, the absorbent member 4 will be further described. 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 absorber 4, and fig. 4(b) is a sectional view of the absorber 4 taken along line IVb-IVb. As described above, the absorbent body 4 has a structure in which the absorbent core 4a positioned on the non-skin side (back sheet 8 side) and the block fiber layer 4b positioned on the skin side (front sheet 2 side) are laminated in the thickness direction T. In the present embodiment, the block fiber layer 4b covers the entire surface of the front sheet 2 side of the absorbent core 4 a. The absorbent core 4a has liquid absorbability and liquid retainability, and mainly absorbs and retains liquid excreta such as urine. The fibrous mass layer 4b absorbs and retains excrement such as loose stool containing solid components and liquid components. However, a part of the liquid component is absorbed and held by the absorbent core 4 a. In the present embodiment, the absorbent core 4a has an absorbent core body 4a-1 and a core wrap 4a-2 covering the absorbent core body 4 a-1. As a material of the core/clad layer 4a-2, for example, a crepe paper can be cited.

Here, when the porous particle layer of patent document 1 is used as the block fiber layer 4b, although it is effective for absorbing and retaining a liquid excrement which is easily separated into a solid component and a liquid component, it is not always effective for a high-viscosity liquid excrement which is difficult to separate into a solid component and a liquid component, that is, a high-viscosity excretion liquid. The reason for this is that, when the porous particle layer absorbs the high-viscosity excreta liquid, not only the solid component but also the liquid component are absorbed and held, and therefore, when pressure is applied to the porous particle layer in this state from the outside, there is a possibility that the internal high-viscosity excreta liquid leaks to the outside. Then, the leaked high-viscosity excreta liquid seeps out to the surface sheet, and rewetting occurs.

Therefore, in the disposable diaper 1 of the present embodiment, a layer including a plurality of block fibers having a predetermined structure is used as the block fiber layer 4b of the absorbent body 4. Such a block fiber layer 4b can appropriately absorb and hold the high-viscosity excreta liquid, and can appropriately suppress the leakage of the high-viscosity excreta liquid inside to the outside even if pressure is applied from the outside. Examples of the high-viscosity excretory fluid include loose stools of infants before eating supplementary food. The following description will be specifically made.

Fig. 5 is a schematic view showing an example of the structure of the block fiber layer 4b and the plurality of block fibers 40 in fig. 4. Fig. 5(a) shows an example of the structure of the block fibers 40, and fig. 5(b) shows an example of the structure of the block fiber layer 4 b. The block fiber layer 4b contains a plurality of block fibers 40. As shown in fig. 5(a), the block fibers 40 include: a core portion 41 formed of a plurality of fibers wound in a lump, having a high fiber density and being hard to be flattened, and formed of a lump of fibers in a state like a lump having a three-dimensional shape as a whole; and a protruding fiber part 42 which is formed of a crimpable fiber protruding outward from the peripheral edge of the core part 41 and has a low fiber density and is easily crushed. As shown in fig. 5(b), in the block fiber layer 4b, the adjacent block fibers 40 are in contact with each other via the protruding fiber portions 42.

The disposable diaper 1 including the block fiber layer 4b can exhibit the following operational effects.

In the block fiber layer 4b, the adjacent block fibers 40 are connected via the protruding fiber portions 42, and the fibers of the protruding fiber portions 42 repel each other and intertwine with each other, thereby forming a void (a void between the core portions 41) formed by the fibers of the protruding fiber portions 42 between the adjacent core portions 41. At this time, since the fibers of the protruding fiber portions 42 are made of fibers having crimpability and the fiber density is relatively low, when pressure (load) is applied to the block-shaped fiber layer 4b, the fibers can be easily shrunk by the pressure. Therefore, since the protruding fiber portions 42 contract to absorb the pressure, the influence of the pressure can be made less likely to reach the core portion 41, and deformation of the core portion 41 can be suppressed.

Here, when pressure is applied to the bulk fiber layer 4b, the specific volume of the bulk fiber layer 4b decreases. However, as a way of reducing this, first, when the pressure is small, the fiber density is low and the number of voids is large, and therefore, the protruding fiber portion 42 which is likely to shrink mainly shrinks, and the specific volume decreases. When the pressure is high, the core 41, which has few voids and is difficult to contract, mainly contracts after the protruding fiber portions 42 have sufficiently contracted, and the specific volume further decreases. Therefore, in reducing the specific volume of the block fiber layer 4b, the shrinkage of the protruding fiber portions 42 and the shrinkage of the core portion 41 proceed substantially in stages.

When such a disposable diaper 1 absorbs a high-viscosity excretory fluid having a property that it is difficult to separate into a solid component and a liquid component, the high-viscosity excretory fluid can be replenished and held to the voids in the core portions 41 of the block fibers 40 and the voids in the protruding fiber portions 42 in the block fiber layer 4 b. At this time, since the core portion 41 having the highest fiber density in the block fiber layer 4b has a high fiber density, when there is a margin in capacity, the high-viscosity excreta liquid temporarily held by the protruding fiber portions 42 can be absorbed and held from the portions adjacent to the protruding fiber portions 42.

When pressure is applied due to a change in the posture of the wearer's body while the disposable diaper 1 is holding a highly viscous excretory fluid, the crimpable fibers of the protruding fiber sections 42 contract according to the pressure to serve as a cushion material, and thus the pressure can be absorbed. Therefore, the pressure can be made to be hardly applied to the core 41. This makes it possible to prevent the high-viscosity excreta liquid held in the void in the core 41 from being pushed out to the outside. Further, the distance between the block fibers 40 is reduced, and the fiber density of the voids of the protruding fiber portions 42, that is, the fiber density around the core portion 41 is increased, whereby leakage from the core portion 41 can be suppressed. This can reduce the surface returning rate, which is the rate at which the high-viscosity excreta liquid once absorbed returns to the surface sheet 2 side, and can increase the retention rate, which is the rate at which the excreta liquid remains in the block fiber layer 4 b.

Here, when a large amount of high-viscosity excretory fluid is held in the voids of the protruding fiber portions 42, it is considered that the high-viscosity excretory fluid held in the voids of the protruding fiber portions 42 is easily pushed out to the outside by contraction of the protruding fiber portions 42. However, since the high-viscosity excreta moves downward (toward the absorbent core 4a) of the protruding fiber sections 42 by its own weight, the high-viscosity excreta is covered with the protruding fiber sections 42 above (toward the topsheet 2), that is, covered above. As a result, even if the void of the protruding fiber part 42 shrinks, the lid (the protruding fiber part 42 above) can prevent the leakage of the high-viscosity excretion liquid to the topsheet 2 side. Further, the high-viscosity excretory fluid no longer present at the cut portion can move through the protruding fiber portions 42 of the block fibers 40 in the middle to the core portions 41 of the block fibers 40 and the gaps of the protruding fiber portions 42 in the portions (for example, cracks of the buttocks) to which no load is applied. This makes it difficult to extrude the liquid to the outside. In addition, in the case of a liquid excrement having a property of being easily separated into a solid component and a liquid component, the solid component can be mainly absorbed by the bulk fiber layer, and the liquid component can be mainly absorbed by the absorbent core. In addition, in the case of a liquid excrement having a property of being easily separated into a solid component and a liquid component, the solid component can be mainly absorbed by the bulk fiber layer, and the liquid component can be mainly absorbed by the absorbent core.

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

However, the fiber density of the core 41 is relatively high and the fiber density of the protruding fiber part 42 is relatively low, which can be confirmed by the following method, for example. That is, 360-degree scanning of the bulk fiber or the bulk fiber layer was performed using a fluoroscopy apparatus FLEX-M863. Specifically, an X-ray fluoroscopic image is taken every 0.2 degrees of rotation of the sample, 1800X-ray fluoroscopic images corresponding to 360 degrees are acquired, and the acquired 1800X-ray fluoroscopic images are pieced together to create a 3D image. Then, regions of the same volume of the core 41 and the protruding fiber 42 are extracted from the 3D image, respectively, and the approximate number of fibers is measured from each extracted region and compared.

Here, it is important that the block fiber layer 4b has the following structure.

3g/cm will be applied to the bulk fibre layer 4b²Pressure (load) of) The specific volume of the block-shaped fiber layer 4b at that time was taken as a reference specific volume (unit: cc/g). In addition, more than 3g/cm will be applied to the bulk fibre layer 4b²The specific volume of the bulk fiber layer 4b at the pressure of (3) is defined as the specific load volume (unit: cc/g). The ratio of the specific load volume to the reference specific volume is a specific volume ratio (unit: dimensionless). The ratio of the change in the specific volume ratio to the change in the pressure applied to the bulk fiber layer 4b was defined as the rate of change (unit: (g/cm))²)^-1). At this time, the block fiber layer 4b of the disposable diaper 1, which exhibits the above-described operational effects, has the following structure. The variation of the pressure (load) applied to the bulk fiber layer 4b was 3g/cm²～5g/cm²The first rate of change was-0.12 (g/cm)²)^-1Above and-0.025 (g/cm)²)^-1The following. Preferably, the first rate of change is-0.10 (g/cm)²)^-1Above and-0.030 (g/cm)²)^-1. Further, the change in the pressure (load) applied to the bulk fiber layer 4b was 25g/cm²～30g/cm²The second rate of change was-0.02 (g/cm)²)^-1Above and less than 0 (g/cm)²)^-1. Preferably, the second rate of change is-0.01 (g/cm)²)^-1Above and-0.005 (g/cm)²)^-1The following. Here, 3g/cm was applied to the bulk fiber layer 4b²The pressure state of (2) simulates a state in which pressure is hardly applied to the disposable diaper 1 in which the wearer stands up, and 25g/cm is applied to the bulk fiber layer 4b²The state of pressure of (2) simulates a state in which a large pressure is applied to the disposable diaper 1 in which the wearer is seated. And, 3g/cm²～5g/cm²The change in pressure (load) of (2) corresponds to the change in shrinkage of the projected fiber part 42, and is 25g/cm²～30g/cm²Corresponds to the change in contraction of the core 41.

In addition, the first rate of change is less than-0.12 (g/cm)²)^-1In the case of (2), the decrease in the specific volume ratio due to the shrinkage of the protruding fiber parts 42 with respect to the change in the pressure applied to the bulk fiber layer 4b is excessively large (the protruding fiber parts 42 have many voids or protruding fibersThe fiber amount of the fiber portion 42 is small), the held high-viscosity excreta liquid is easily discharged. On the other hand, the first change rate exceeds-0.025 (g/cm)²)^-1In the case of (2), since the specific volume ratio decreases excessively (the voids of the protruding fiber portions 42 are small, the fiber amount of the protruding fiber portions 42 is large, or the like) due to the shrinkage of the protruding fiber portions 42 with respect to the change in the pressure applied to the block fiber layer 4b, it is difficult to sufficiently maintain the high-viscosity excretory fluid. In addition, the rate of change at 2 nd was less than-0.02 (g/cm)²)^-1That is, when the absolute value exceeds 0.015, the specific volume ratio due to the shrinkage of the core portion 41 against the change in the pressure applied to the bulk fiber layer 4b is excessively decreased (the number of voids in the core portion 41 is large, the fiber amount in the core portion 41 is small, or the like), so that the core portion 41 is easily deformed and the high-viscosity excreted liquid easily seeps out.

The specific volume of the bulk fiber layer 4b is appropriately set in accordance with the required absorption amount of the high-viscosity excreta liquid, and the like. In the present embodiment, the pressure (load) applied to the block fiber layer 4b is 3g/cm²In this case, the specific volume of the bulk fiber layer 4b may be, for example, 50 to 90cc/g, and the specific volume under pressure (load) may be 25g/cm²In this case, the specific volume is, for example, 20 to 35 cc/g. However, when the specific volume of the block fiber layer 4b is relatively small, the fiber density of the block fiber layer 4b becomes relatively high, and the absorption amount of the high-viscosity excretory fluid becomes relatively small, but it tends to be relatively difficult to release the high-viscosity excretory fluid.

The sizes of the core 41 and the block fibers 40 are appropriately set according to the required absorption amount of the high-viscosity excreta liquid. In the present embodiment, the core 41 and the block fibers 40 are not spherical but block-shaped, and the protruding fiber portions 42 covering the outer peripheral surface of the core 41 are not uniform in thickness. Therefore, in the present embodiment, the core 41 and the block fibers 40 are regarded as balls, and the protruding fiber portions 42 are regarded as layers having a uniform thickness covering the outer peripheral surface of the core 41. In this case, the average radius r of the core 41 is, for example, in the range of 0.1 to 0.5cm (the diameter 2r is, for example, in the range of 0.2 to 1 cm). The average thickness d of the protruding fiber part 42 is, for example, in the range of 0.2 to 0.6 cm. Therefore, the average radius (r + d) of the block fibers 40 is, for example, in the range of 0.3 to 1.1cm (the diameter 2 × (r + d), for example, in the range of 0.6 to 2.2). However, if the diameter of the core portion 41 is relatively large, the amount of high-viscosity excreta liquid that can be stably held is relatively large, but 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 amount of high-viscosity excreta liquid that can be stably held is relatively small, but the protruding fiber portion tends to be less susceptible to the body pressure of the wearer.

In the present embodiment, the ratio (d/2r) of the thickness d of the protruding fiber part 42 to the diameter 2r of the core part 41 is preferably 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 parts 42 on the surface of the core part 41 in the block fiber 40 is preferably 0.4 times or more and 2 times or less, and more preferably 0.7 times or more and 1.5 times or less the average diameter 2r of the core part 41. In this way, when the average thickness d of the protruding fiber portions 42 is within the above range, the high-viscosity excretory fluid can be more appropriately held in the voids of the protruding fiber portions 42, and when pressure is applied to the bulk fiber layer 4b, the voids of the protruding fiber portions 42 contract more appropriately, and the pressure can be more appropriately absorbed. This can prevent the pressure from being applied to the core 41.

Here, when the average thickness d of the protruding fiber portions 42 is less than 0.4 times the average diameter 2r of the core portion 41, a sufficient void of the protruding fiber portions 42 cannot be secured, pressure is easily applied to the core portion 41, and high-viscosity excreta liquid easily seeps out from the core portion 41. When the average thickness d of the protruding fiber portions 42 is made to exceed 2 times the average diameter 2r of the core portion 41, the protruding fiber portions 42 shrink while the protruding fiber portions 42 hold a large amount of high-viscosity excreta liquid, and the high-viscosity excreta liquid easily seeps out of the protruding fiber portions 42.

Mass of each 1 block-like fiber 40, per 1cm³The number of the block fibers 40 in the block fiber layer 4b is appropriately set according to the required absorption amount of the high-viscosity excreta liquid and the like. In the present embodiment, the mass of the block-shaped fibers is, for example, 0.5 to 8 mg/piece. As per 1cm³Block fibers ofThe number of the block fibers 40 in the layer 4b (but in an unloaded state) is, for example, 2.5 to 30/cm³. However, if the mass of the block-like fibers 40 is 1cm per 1 block³The relatively large number of the block fibers 40 in the block fiber layer 4b relatively increases the amount of the high-viscosity excreta liquid to be absorbed.

In a preferred embodiment of the present embodiment, the pressure applied to the block fiber layer 4b is 25g/cm²The specific volume ratio is 0.2 or more and 0.7 or less, and more preferably 0.3 or more and 0.6 or less.

At 25g/cm²When the specific volume ratio under pressure is in this range, the voids of the protruding fiber portions 42 can be more appropriately contracted when pressure is applied to the bulk fiber layer 4 b. This makes it possible to sufficiently increase the fiber density of the projecting fiber portions 42 in the projecting fiber portions 42, and to further suppress the leakage of the high-viscosity excreta liquid in the voids of the projecting fiber portions 42 to the outside. In addition, in the core portion 41, the protruding fiber portions 42 serve as a cushion material and absorb pressure more appropriately, so that pressure is less likely to be applied to the core portion 41, and the leakage of the high-viscosity excreta liquid in the voids of the core portion 41 to the outside can be further suppressed. Here, when the specific load volume ratio is less than 0.2, the protruding fiber portion 42 shrinks too much due to the pressure, and the high-viscosity excreta liquid is likely to leak out mainly from the protruding fiber portion 42. When the ratio of the specific load capacity exceeds 0.7, the protruding fiber part 42 shrinks too little by pressure, and the high-viscosity excreta liquid is likely to leak out mainly from the core part 41.

When the ratio of the voids between the core portions 41 in the block fiber layer 4b is set as the void ratio, the pressure applied to the block fiber layer 4b is set to 3g/cm²The porosity at that time is set as a first porosity, and the pressure applied to the block fiber layer 4b is set to 25g/cm²The porosity at that time is set as a second porosity. In this case, in a preferred embodiment of the present invention, the first porosity is 40% or more and 80% or less, and the second porosity is 2% or more and 60% or less. The first porosity is more preferably 50% or more and 80% or less, and the second porosity is more preferably 2% or more and 50% or less.

If the first porosity is in the rangeUnder the condition that almost no pressure is applied to the bulk fiber layer 4b (3 g/cm)²) The void ratio of (2) is 40% to 80%, a sufficient core portion 41 for replenishing the high-viscosity excreta liquid can be secured, and a sufficient protruding fiber portion 42 for absorbing the pressure can be secured. When the second porosity is in this range, that is, when a pressure is applied to the bulk fiber layer 4b (25 g/cm)²) When the porosity of (2) to (60%) is used, the protruding fiber parts 42 can be sufficiently shrunk while ensuring sufficient protruding fiber parts 42 for holding the high-viscosity excretory fluid, and the application of pressure to the core 41 can be suppressed. When the 1 st porosity is less than 40%, a void that can be appropriately contracted when the pressure is increased cannot be secured in the protruding fiber portion 42, and when it exceeds 80%, a void that can sufficiently absorb the high-viscosity excreta cannot be secured in the core portion 41. When the 1 st porosity is less than 5%, a sufficient space for holding the high-viscosity excreta liquid cannot be secured in the protruding fiber part 42, and when it exceeds 60%, it is difficult to hold the high-viscosity excreta liquid in the space of the protruding fiber part 42.

In another embodiment, at least a part of the top sheet 2 may have a plurality of through-holes (not shown) that penetrate in the thickness direction T toward the block fiber layer 4 b. The plurality of through-holes extend from one surface to the other surface of the surface sheet 2, and function not only as holes through which a liquid component can permeate but also as holes through which a solid component can permeate. Therefore, the high-viscosity excreta liquid can permeate the top sheet 2 through the 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, i.e., the porosity, is preferably 5 to 90%. The pore diameter of the through-holes is preferably smaller than the diameter of the block fibers 40 contained in the block fiber layer 4b, the upper limit is preferably smaller than 1cm, and the lower limit is not particularly limited, and may be, for example, 0.08cm or more. The number of the through holes is preferably 0.3 to 30/cm². The surface sheet 2 has a low basis weight (exemplified by 8 to 20 g/m)²) Since there are a plurality of voids, it can be referred to as a surface sheet 2 having a plurality of through-holes.

The block fibers 40 contained in the block fiber layer 4b are preferably made of hydrophilic fibers. This can impart hydrophilicity to the block fiber layer 4 b. Examples of the hydrophilic fiber include at least one of a hydrophilic fiber and a hydrophobic fiber subjected to hydrophilization treatment. Examples of the hydrophilic fiber include fibers made of hydrophilic materials such as cotton and pulp, examples of the hydrophobic fiber include polyester fibers and polyolefin fibers, and examples of the hydrophilization treatment include treatment with a surfactant and a hydrophilic agent. The block fibers 40 may contain hydrophobic fibers within a range capable of maintaining hydrophilicity. By providing the block fiber layer 4b with hydrophilicity, excrement can be efficiently permeated, absorbed, and retained. In the present embodiment, the block fibers 40 are preferably fiber balls. A fiber ball is a mass of fibers that has an appearance that is relatively close to the shape of the ball. By forming the block fibers 40 from fiber balls, the block fibers 40 and the block fiber layers 4b having the predetermined core portions 41 and the protruding fiber portions 42 can be easily formed.

When the fiber balls are used as the block fibers 40, the fiber balls produced by a conventionally known method can be used, and commercially available products can also be used. Examples of the method for producing the fiber balls include a method of winding and granulating fibers (e.g., Japanese patent application laid-open No. 2016-94692), a method of thermally welding or thermally shrinking fibers to form particles (e.g., Japanese patent application laid-open Nos. 2000-345457 and 7-39659), and a method of granulating fibers with a binder (e.g., Japanese patent application laid-open Nos. 63-50373 and 11-105030). For example, the following method is disclosed in japanese patent application laid-open No. 2016-94692: in a truncated cone-shaped container in which air flows by rotating, fibers that are thermally weldable and/or fibers that are not thermally weldable or are difficult to thermally weld are three-dimensionally rotated by the rotation of the air and kneaded into a mass, which is molded into a fiber ball. Further, Japanese patent application laid-open No. 2000-345457 discloses a method for producing a fiber ball by molding a thermally bondable conjugate fiber containing a thermoplastic elastomer as a thermally bondable component and a polyester-based conjugate fiber having high dry heat shrinkability while thermally shrinking the conjugate fiber. Further, japanese patent application laid-open No. 7-39659 discloses the following method: a plurality of synthetic fiber crimped yarns are aligned and bundled, then cut, and then heat-treated at a temperature lower than the melting point of the synthetic fiber crimped yarns to develop crimps of the yarns, thereby producing fiber balls. In each of these methods, for example, by controlling the molding conditions and the heat treatment conditions, the block fibers 40, which are fiber balls having the core portions 41 and the protruding fiber portions 42, can be formed.

For the production of the fiber balls, a commercially available fiber Ball production apparatus (exemplified by Ball Fibers Forming Machine CMM1, Mass., a pelletization apparatus) was used. The fiber balls produced by the fiber ball production apparatus include, for example, fiber balls obtained by molding thermoplastic resin fibers (for example, polyester fibers) into fiber balls. When the thermoplastic resin fibers are formed into fiber balls, fibers having crimpability are used as the fibers in the fiber balls. Thus, the protruding fiber part is easily contracted when pressure is applied, and a fiber ball in which the protruding fiber part can be easily expanded when the pressure is removed can be formed. For example, by controlling the molding conditions, the block fibers 40 can be formed as fiber balls having the core portions 41 and the protruding fiber portions 42.

In the present embodiment, the fibers of the core 41 in the block fibers 40 are preferably the same as those of the protruding fiber portions 42. Therefore, since the fibers are continuously connected from the core 41 to the protruding fiber portions 42, the high-viscosity excreta liquid can be more easily replenished by the protruding fiber portions 42 and guided to the core 41. At the same time, since the predetermined protruding fiber portions 42 and the core portions 41 can be formed more reliably, the core portions having a high fiber density can be made more difficult to crush more reliably, and the protruding fiber portions having a low fiber density can be made easier to crush. Thus, when pressure is applied to the block-shaped fiber layer, the voids of the protruding fiber portions are appropriately contracted to serve as a cushion member, and the pressure can be appropriately absorbed, whereby the pressure can be further prevented from being applied to the core portion.

In the present embodiment, it is preferable that the fibers constituting the plurality of block fibers 40 are not thermally welded to each other. Thus, the fibers can be easily contracted and extended in accordance with the application and removal of pressure. Further, when pressure is applied to the disposable diaper 1, the fibers of the protruding fiber portions 42 can be easily contracted, and the pressure can be made more difficult to be applied to the core portion 41. Further, when the voids of the protruding fiber portions 42 and the voids between the core portions 41 absorb the high-viscosity excreta liquid and swell, the intersections between the fibers can be suppressed from interfering with the swelling.

Further, some or all of the fibers constituting the plurality of block fibers 40 may be bonded to each other. In this case, the bulk fibers 40 can be provided with compression resistance or compression rebound. Examples of the joining method include a method of thermally welding fibers to each other and a method of bonding fibers to each other (binder fiber, adhesive, etc.). This makes it possible to suppress a decrease in the specific volume (void ratio) of the bulk fiber layer 4b and a decrease in the absorption and retention performance of the bulk fiber layer 4b associated therewith when the disposable diaper 1 is used (exemplified by the body pressure of the wearer).

It is preferable to apply an adhesive (hot melt adhesive, for example) to the interface between the block fiber layer 4b and the top sheet 2 and/or the interface between the block fiber layer 4b and the absorbent core 4 a. This can fix the block fibers 40 contained in the block fiber layer 4 b. From the viewpoint of permeation of an excretion liquid containing a high-viscosity excretion liquid, the adhesive is preferably applied not to the entire interface but in a pattern such as a dot, a spiral, or a stripe. Examples of the method of applying the adhesive include spiral coating, coater coating, curtain coater coating, and heat gun (japanese patent No. サミットガン) coating. The amount (basis weight) of the adhesive applied is, for example, 3 to 100g/m²。

In the present embodiment, as a preferable mode, the basis weight of the adhesive between the block fiber layer 4b and the top sheet 2 is lower than the basis weight of the adhesive between the block fiber layer 4b and the absorbent core 4 a. That is, since the basis weight of the adhesive between the block fiber layer 4b and the top sheet 2 is relatively small, it is possible to suppress the space of the block fiber layer 4b from being difficult to be used for absorption and transfer of the high-viscosity excretory fluid by the adhesive. This enables the block fiber layer 4b to quickly replenish and maintain the high-viscosity excretory fluid. Further, since the basis weight of the adhesive between the block fiber layer 4b and the absorbent core 4a is relatively large, the contact area between the block fiber layer 4b and the absorbent core 4a is increased, and moisture of high-viscosity excreta or other excreta can be easily transferred to the highly hydrophilic absorbent core 4 a.

The thickness, basis weight, and the like of the block fiber layer 4b are appropriately adjusted according to the required absorption amount of the high-viscosity excreta liquid, and the like. In the present embodiment, the thickness of the block fiber layer 4b is, for example, 1 to 10 mm. The thicker the thickness of the block fiber layer 4b, the more the high-viscosity excreta liquid is absorbed, but the wearing feeling tends to be reduced. The basis weight of the block fiber layer 4b may be, for example, 25 to 500g/m². The larger the basis weight of the block fiber layer 4b, the more easily the high-viscosity excretory fluid is held, but the wearing feeling tends to be reduced. The thickness, basis weight, and the like of the block fiber layer 4b may be constant as a whole or may be partially different.

Next, a method for manufacturing the disposable diaper 1 of the present embodiment will be described. Fig. 6 is a schematic diagram showing a configuration example of the apparatus for manufacturing an absorbent body according to the embodiment.

The first step is a step of forming the absorbent core body 411. As shown in fig. 6, the absorbent core body 411 is formed by using the suction tube 110 rotating in the conveyance direction MD and the absorbent material supply section 120 having a cover covering the suction tube 110. On the circumferential surface 111 of the suction tube 110, recesses 112 are formed at a desired pitch in the circumferential direction as a mold for filling the absorbent material. When the suction cylinder 110 rotates to cause the concave portion 112 to enter the absorbent material supply portion 120, the suction portion 113 acts on the concave portion 112, and the absorbent material supplied from the absorbent material supply portion 120 is vacuum-sucked into the concave portion 112. The absorbent material supplied from the absorbent material supply unit 120 contains the hydrophilic fibers F supplied from a pulverizer (not shown) and the super absorbent polymer P supplied from the particle supply unit 121 at a predetermined mass mixing ratio. Thus, the absorbent core body 411 is formed in the concave portion 112. The absorbent core body 411 contains the hydrophilic fibers F and the super absorbent polymer P in a mixed state. The absorbent core main body 411 formed in the concave portion 112 is transferred to the lower core wrap 91 traveling in the conveyance direction MD by the transfer application portion 150. A hot-melt adhesive is applied to the upper surface of the lower core cladding 91, and the absorbent core main body 411 is joined to the lower core cladding 91 by the hot-melt adhesive. The absorbent core main body 411 transferred to the lower core wrap layer 91 travels in the conveyance direction MD.

The next step is a step of laminating an upper core wrap 92 on the absorbent core body 411 traveling in the conveyance direction MD. A hot-melt adhesive is applied to the lower surface of the upper core cladding 92, and the absorbent core body 411 is joined to the upper core cladding 92 by the hot-melt adhesive. In this way, a continuous body of a laminated body is formed in which the upper core cladding 92, the absorbent core body 411, and the lower core cladding 91 are laminated in this order. The continuous body is cut into a predetermined shape by a pair of

rollers

300, 301 to form an absorbent core 4a having an absorbent core body 4a-1 and a core wrap 4a-2 covering the absorbent core body 4 a-1.

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

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

Through the above-described steps, an absorbent body 4 having an absorbent core 4a and a block fiber layer 4b laminated on one surface of the absorbent core 4a is produced. The disposable diaper 1 using the absorbent member 4 can be manufactured by a conventionally known method.

In a preferred embodiment of the present embodiment, as shown in fig. 4, in the absorbent body 4, the bulk fiber layer 4b is provided so as to cover the entire skin-side surface of the absorbent core 4 a. However, the structure of the absorbent body 4 (block 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 cross-sectional view VIIb-VIIb of the absorbent body 4A. In the absorbent body 4A, the bulk fiber layer 4bA is provided in a part of a region corresponding to the intermediate portion 12 of the disposable diaper 1 in the skin-side surface of the absorbent core 4A. The portion where the block-shaped fiber layer 4bA is provided is, for example, a portion located on the side of the center back side portion 13 in the region corresponding to the intermediate portion 12 of the disposable diaper 1. The absorbent body 4A can suppress diffusion of the high-viscosity excreta excreted from the wearer, and can absorb the high-viscosity excreta mainly into the bulk fiber layer 4 bA.

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 cross-sectional view taken along VIIIb-VIIIb of the absorbent body 4B. In the absorbent body 4B, the bulk fiber layer 4bB is provided in a part of the region corresponding to the intermediate portion 12 of the disposable diaper 1 on the skin-side surface of the absorbent core 4 a. The portion provided with the block-shaped fiber layer 4bB is, for example, a portion located on the side of the center back side portion 13 out of portions extending in the longitudinal direction L at both ends in the width direction W in a region corresponding to the intermediate portion 12 of the disposable diaper 1. The absorbent body 4B can prevent the high-viscosity excreta excreted from the wearer from leaking over the pair of leakage preventing walls 7a, 7B. Therefore, the absorbent body 4B is particularly useful as a diaper for a baby of a relatively high age taking a lateral posture or opening and closing legs.

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 absorber 4C, and fig. 9(b) is a sectional view of IXb-IXb of the absorber 4C. In the absorbent body 4C, the block fiber layer 4bC is provided in a part of the region corresponding to the back side portion 13 of the disposable diaper 1 on the skin-side surface of the absorbent core 4 a. The absorbent body 4C can suppress the flow of the high-viscosity excreta liquid excreted from the wearer toward the back of the wearer. Therefore, the absorbent body 4C is particularly useful as a diaper for a baby of a relatively short month age who frequently takes a supine posture.

Examples

The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the examples.

(I) Preparation of samples

< Block fibers >

Bulk fibers were produced by the following method. Polyester Fibers (fineness: 7.4T, fiber length: 32mm) hydrophilized on the fiber surface were subjected to a cotton-like pelletization process using an air-flow type pelletization apparatus (Ball Fibers Forming Machine CMM1, Mass.) to obtain block Fibers A to D depending on the molding conditions.

< surface sheet >

The surface sheet was produced by the following method. A fiber web (basis weight 10 g/m) was produced by raising a fiber obtained by attaching a hydrophilic oil to a core-sheath type composite fiber (core-sheath ratio 50: 50 (cross-sectional area ratio), fineness 4.4dtex, fiber length 51mm) containing polyethylene terephthalate (PET) as a core component and high-density polyethylene (HDPE) as a sheath component²). The fiber web was subjected to a through-air bonding treatment to produce a through-air nonwoven fabric (thickness 1.0 mm).

< absorbent core >

An absorbent core was produced by the following method. Cotton pulp obtained by pulverizing fluff pulp (スーパーソフト, manufactured by インターナショナルペーパー Co., Ltd.) and a super absorbent polymer (SA 50, manufactured by Sumitomo Seiko Co., Ltd.) were mixed so as to be uniformly dispersed, and then the mixture was laminated to produce a cotton pulp having a length of 300mm, a width of 120mm and a basis weight of 250g/m². + -. 3% of superabsorbent polymer having a basis weight of 250g/m²(iii) a stack of ± 3%. The laminate thus produced was sandwiched by 2 sheets of crepe paper coated with a hot-melt adhesive on the laminate-side surface, and then press-formed into a thickness of 2.5mm by a press device.

< production of samples of examples and comparative examples >

The samples of examples 1 to 4 and comparative example 1 were produced by the following method.

(1) Example 1: on the upper side of the central part of the absorbent core, the basic weight is 100g/m in the area of 120mm length multiplied by 100mm width²A plurality of block fibers a were layered in a ± 3% manner. Then, a surface sheet coated with a hot melt adhesive in a pattern in which only the plurality of block fibers are partially unbonded is bonded to the upper surface of the absorbent core.

(2) Example 2: the same as in example 1 was conducted except that the block fibers A were changed to block fibers B.

(3) Example 3: the same as in example 1 was conducted except that the block fibers A were changed to block fibers C.

(4) Example 4: the same as in example 1 was conducted except that the block fiber A was changed to a block fiber D.

(5) Comparative example 1: the procedure of example 1 was repeated, except that the block fibers A were changed to cotton balls (manufactured by スズラン, スズラン Cotton ball No. 3).

(II) evaluation of samples

(II-1) evaluation of Block fibers

First, the average diameter 2r of the core, the average diameter 2 × (r + D) of the block fibers, and the average thickness D of the protruding fiber portions were determined for the block fibers a to D and the cotton balls, which are the block fibers of examples 1 to 4 and comparative example 1, by the following methods.

< average diameter of core 2r >)

(i) The lens magnification was set to a magnification (for example, 20 to 200 times) of the entry screen of the block fibers to be measured by a digital microscope VHX-2000 (KEYENCE, K.K.).

(ii) The image size was set to 1600 pixels (H) × 1200 pixels (V).

(iii) The block-shaped fiber of the measurement object was placed on the transmission measurement unit, and an image was taken.

(iv) After saving the image and recalling it, the "measurement", "automatic area measurement", "brightness", and "start measurement" are selected.

(v) The binarization threshold value is set to 0, and the extraction parameters are selected from 'dark', 'hole filling', 'small particle removal', and binarization is performed.

(vi) The automatically calculated area of the extraction area is recorded as the projected area of the bulk fiber.

(vii) The above-mentioned (iii) to (vi) were performed for 10 block-shaped fibers, and the projected areas of the 10 block-shaped fibers were obtained. The average Av of these 10 projected areas was found.

(vii) Diameter for the case where the average value Av of the obtained projected areas is taken as the area of a circleConverted value, by (4 x Av/pi)^0.5The diameter 2r of the core 41 was obtained as an approximate value.

< average diameter of Block fibers 2X (r + d) >

(ii) The image size was set to 1600 pixels (H) × 1200 pixels (V).

(iii) A block-shaped fiber to be measured is placed on a transmission measuring unit, and an image is taken.

(iv) The image was saved and recalled and the longest length (major axis) of the block fiber was measured.

(v) The longest length (short diameter) of the block fiber was measured under the condition of being orthogonal to the measurement line of the long diameter.

(vi) The above (iii) to (v) were performed on 10 block-shaped fibers, and the major and minor diameters of the 10 block-shaped fibers were determined. The average value r of the 10 major diameters was determined_LAnd average value r of minor axis_S。

(vii) The average value r of the obtained major axes is obtained_LAverage value r of the minor axis_SAverage value of (r)_L+r_S) (ii)/2 as the diameter of the block fiber 2 x (r + d) (approximate value).

< average thickness d of projected fiber portion >

(i) The thickness d (approximate value) of the protruding fiber part 42 is calculated by subtracting the diameter 2r (approximate value) of the core part 41 from the diameter 2 × (r + d) (approximate value) of the block fiber and multiplying by 1/2.

< results >

Fig. 10 shows an example of an image captured when the average diameter 2r of the core portion, the average diameter 2 × (r + d) of the lump fibers, and the average thickness d of the protruding fiber portion are obtained, and an image obtained by binarizing the image. Fig. 10 shows an optical microscope image of the block fibers 40 in each of examples 1 to 4 and comparative example 1 and an image obtained by binarizing them. As shown in the figures, it was found that the protruding fiber portions were present in a wide range around the core portion in each of the samples of examples 1 to 4, but the protruding fiber portions were present only in a very small amount in the sample of comparative example 1. The results of obtaining the average diameter 2r of the core portion and the average thicknesses d and d/2r of the protruding fiber portions are shown in table 1 below. The d/2r range is preferably 0.4 to 2, more preferably 0.7 to 1.5.

[ Table 1]

(II-2) evaluation of samples of examples 1 to 4 and comparative example 1

Specific volumes, specific volume ratios, and specific volume ratio change rates were determined for the samples of examples 1 to 4 and comparative example 1 by the following methods.

< specific volume >

The following measurements were carried out on the block fibers A to D and cotton balls of examples 1 to 4 and comparative example 1, respectively.

(i) In a cylinder (18 cm in cross-sectional area) of 48mm diameter²) A plurality of block fibers were uniformly fed therein, and a total of 0.180g (equivalent to 100 g/m)²) As a measurement sample. The measurement sample simulates the block fiber layer 4 b.

(ii) Thickness measurer: the thickness of the measurement sample at the center of the cylinder was measured using a dial type thickness gauge large model J-B (manufactured by Kawasaki corporation). At this time, 3g/m was applied to the sample by the weight of the measuring part of the thickness measuring instrument²The state of the load of (a). This thickness was taken as a reference thickness. The specific volume at this stage is the above-mentioned reference specific volume, and is calculated from the actually measured reference thickness by the following calculation formula.

Reference specific volume (cc/g) ═ pi × { cylinder radius (cm) }²X measured reference thickness (cm)/mass of sample (0.180g)

(iii) Next, the thickness of the measurement sample was measured while a weight of a predetermined mass was placed on the top surface of the grip portion of the thickness measuring instrument so as to apply a predetermined pressure (load) to the measurement portion of the thickness measuring instrument. At this time, the thickness measuring device is in a state where a predetermined load is applied by the weight of the measuring unit and the weight. This thickness was taken as the load thickness. The specific volume at this stage is the above-mentioned specific volume under load, and is calculated from the measured thickness under load by the following calculation formula.

Specific load capacity (cc/g) ═ pi × { cylinder radius (cm) }²X measured thickness of load (cm)/mass of sample (0.180g)

< specific volume ratio >

The specific volume ratio (dimensionless) at each load was calculated by dividing the specific volume under load (load) at each load calculated by the above method by the reference specific volume. The specific volume ratio can be said to be 3g/m in pressure (load)²The specific volume of (b) is a value obtained by normalizing the specific volume under each load.

< Change Rate of specific volume ratio >

Based on the graph of the specific load capacity with respect to the pressure (load) calculated by the above method, the rate of change of the specific capacity ratio with respect to the change of the pressure (load), that is, the rate of change of the specific capacity ratio is calculated. For example, the change in pressure (load) is 3g/cm²～5g/cm²The change rate of the specific volume ratio in the case of (2) is calculated by the following equation.

(Rate of change ((g/cm)²)^-1)＝{(5g/cm²Specific volume ratio of (2) - (3 g/cm)²Specific volume ratio) }/{ (5 g/cm)²)-(3g/cm²)}

Further, for each of the samples of examples 1 to 4 and comparative example 1, the mass of the block fibers, the number of block fibers per unit volume, and the porosity between the core portions of the block fiber layers were determined by the following methods.

< quality of bulk fiber >

The mass of a predetermined number of, for example, 50 block-shaped fibers was measured by an electronic balance, and the mass of each 1 block-shaped fiber was calculated by dividing the mass by the number.

< number of bulky fibers per unit volume >

The number N of block fibers per unit volume in the block fiber layer is calculated by the following equation.

N (pieces/cm)³) N (pieces)/(0.180 (g) × reference specific volume (cc/g))

Wherein n is the number of the block fibers put into the cylinder as described above < specific volume > (i).

< porosity between core portions >

The ratio of the voids between the plurality of core portions in the block fiber layer, that is, the inter-core void ratio F1 is calculated by the following equation.

F1(％)＝(1-(4/3)×π×r³×N)×100

Where r is the radius of the core and N is the number of blocky fibers per unit volume.

In addition, the permeation time, the surface return rate and the retention rate were determined for each of the samples of examples 1 to 4 and comparative example 1. The permeation time, surface recovery rate and retention rate were determined as follows.

< evaluation method of penetration time, surface Return Rate and holding ratio >

(i) For each of the samples of examples 1 to 4 and comparative example 1 (including a block fiber layer including a surface sheet and a plurality of block fibers and an absorbent core), a cylinder having a diameter of 60mm, to the bottom of which a 10-mesh metal mesh was attached, was placed on the central portion.

(ii) 15g of an artificial soft stool having a viscosity adjusted to 2000 mPas was weighed accurately and injected into the cylinder with a syringe.

(iii) The stopwatch was started to time while the injection of the artificial soft feces was started, the artificial soft feces was transferred to the sample through the metal net, the time until the metal net at the bottom of the cylinder started to be exposed was measured, and the measured time was taken as the permeation time. However, when the metal mesh was not exposed even after 3 minutes had elapsed, the process was terminated.

(iv) After 3 minutes from the injection of the artificial stool, the cylinder was taken out, a 10cm × 10cm filter paper (manufactured by アズワン, NO1 filter paper) was placed on the sample, and further 20g/cm was placed on the filter paper²The loaded weight was left standing for 30 seconds.

(v) After 30 seconds, the mass of the filter paper is measured, and the original mass of the filter paper is subtracted, so that the return quantity of the artificial soft stool is calculated. The obtained value of the return amount is divided by the injection amount of the artificial soft stool to obtain the surface return rate.

(vi) Subsequently, the surface sheet was peeled off, and the mass fiber layer (including artificial loose stool) having a circular diameter of 85mm centered on the cylinder was taken out and the mass was measured.

(vii) The mass (0.567g) of the original block fiber layer before the artificial soft stool was absorbed was subtracted from the measured mass in the range of 85mm, and the amount of the artificial soft stool held by the block fiber layer was calculated. The retention was determined by dividing the value of the amount of the retained product by the amount of the injected artificial soft stool.

< preparation method of Artificial Soft stool >

The preparation method of the artificial soft stool is as follows.

First, a reagent containing the following components at the following ratios was prepared. That is, the reagent was composed of 71.9 mass% of ion-exchanged water, 1.0 mass% of NaCl, 15.0 mass% of glycerol, 2.0 mass% of NaCMC, 0.05 mass% of tritium nucleus X-100, 0.05 mass% of Red No. 102, and 10.0 mass% of powdered cellulose. Then, the viscosity of the reagent was adjusted to 2000mPa · s with ion-exchanged water to prepare an artificial soft stool.

The results of the above measurements on the samples of examples 1 to 4 and comparative example 1, the bulk fibers a to D, and the cotton balls are summarized in table 2.

[ Table 2]

Fig. 11 is a graph showing the relationship between the load (pressure) and the specific volume of the bulk fiber layer 4b in each of the samples of examples 1 to 4 and comparative example 1. The horizontal axis represents load (pressure) (g/cm)²) The vertical axis represents the specific volume (cc/g). Diamond (o) is example 1, quadrilateral (□) is example 2, triangle (Δ) is example 3, circle (. smallcircle.) is example 4, and inverted triangle (. lambertian.) is comparative example 1. In the samples of examples 1 to 4, the specific volume sharply decreased at the initial stage of the increase in the load (pressure), but the specific volume increased as the increase in the load (pressure) progressedThe reduction of the product becomes slow. On the other hand, in the sample of comparative example 1, the load (pressure) decreased at substantially the same rate as the load increased.

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 shows a load (pressure) of 3g/cm²The specific volume value of (a) is a graph obtained by normalizing the specific volume value of the graph of fig. 11. The horizontal axis represents load (pressure) (g/cm)²) The ordinate represents the specific volume ratio (dimensionless). Diamond (o) is example 1, quadrilateral (□) is example 2, triangle (Δ) is example 3, circle (. smallcircle.) is example 4, and inverted triangle (. lambertian.) is comparative example 1. The trend of the graphs of examples 1 to 4 was more clearly different from the trend of the graph of comparative example 1 by normalization.

Will bring the load (pressure) from 3g/cm²The change is 5g/cm²Change of specific volume ratio and load (pressure) from 25g/cm²The change is 30g/cm²The change in specific volume ratio was compared. As shown in Table 1, the samples of examples 1 to 4 were-0.12 to-0.025 (g/cm)²)^-1And-0.02 to 0 (g/cm)²)^-1The range of (1). On the other hand, the samples of comparative example 1 were-0.0137 and-0.0046, respectively.

This is because, in the samples of examples 1 to 4, it is considered that the specific volume rapidly decreases due to shrinkage of the protruding fiber portion at the initial stage of increase of the load (pressure), but when the increase of the load (pressure) progresses and the protruding fiber portion is hard to shrink, the core portion shrinks and the specific volume decreases slowly. On the other hand, in the sample of comparative example 1, since there are almost no protruding fiber portions, it is considered that the core portion shrinks from the initial stage of the increase of the load (pressure) and decreases at substantially the same rate. That is, the effect of the protruding fiber part of examples 1 to 4 was confirmed.

Further, 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 exceeded 20%, and the retention rate did not reach 40%. This confirmed the effects of the block fiber layers 4b of examples 1 to 4. That is, the block fiber layers 4b of examples 1 to 4 can maintain or improve the absorption performance for the high-viscosity excreta liquid, and can suppress the high-viscosity excreta liquid from oozing out (rewetting) into the top sheet 2.

Further, according to the graphs of Table 1, FIG. 11 and FIG. 12, the load (pressure) was adjusted from 3g/cm²The change is 5g/cm²The rate of change of the specific volume ratio is preferably-0.12 to-0.025 (g/cm)²)^-1In a range such that the load (pressure) is from 25g/cm²The change is 30g/cm²The change rate of the specific volume ratio is preferably-0.02 to 0 (g/cm)²)^-1The range of (1). Further, the load (pressure) was 25g/cm²The specific volume ratio is preferably in the range of 0.2 to 0.7. The load (pressure) was 3g/cm²The porosity in the case of (A) is preferably in the range of 40% to 80%, and the load (pressure) is 25g/cm²The porosity in the case of (3) is more preferably in the range of 2% to 60%.

Description of reference numerals

1 Disposable diaper (absorbent article)

4 absorbent body

4a absorbent core

40 Block fiber

4b bulk fiber layer

41 core part

42 protruding fiber part

Claims

1. An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body positioned between the top sheet and the back sheet,

the absorbent body is provided with:

an absorbent core; and

a bulk fiber layer located on the topsheet-side surface of the absorbent core and comprising a plurality of bulk fibers,

the plurality of bulk fibers each comprise:

a core part formed by massive fibers, wherein the fibers have high density and are difficult to flatten; and

a protruding fiber part formed of a crimpable fiber protruding outward from the peripheral edge of the core part, having a low fiber density and being easily flattened,

adjacent block fibers are connected with each other via the protruding fiber portions,

will apply 3g/cm to the bulk fiber layer²The specific volume of the blocky fiber layer is used as a reference specific volume when the pressure is applied, and more than 3g/cm is applied to the blocky fiber layer²The specific volume of the bulk fiber layer at the pressure of (3) is defined as a specific volume under load, a ratio of the specific volume under load to the reference specific volume is defined as a specific volume ratio, and a ratio of a change in the specific volume ratio to a change in the pressure applied to the bulk fiber layer is defined as a rate of change,

the variation of the pressure applied to the fibrous layer block was 3g/cm²～5g/cm²The first rate of change is-0.12 (g/cm)²)^-1Above and-0.025 (g/cm)²)^-1In the following, the following description is given,

the change in pressure applied to the fibrous layer was 25g/cm²～30g/cm²The second rate of change is-0.02 (g/cm)²)^-1Above and less than 0 (g/cm)²)^-1。

2. The absorbent article according to claim 1,

the average thickness of the protruding fiber parts on the surface of the core part in the block fiber is 0.4 times or more and 2 times or less the average diameter of the core part.

3. The absorbent article according to claim 1 or 2,

the fibers of the core in the block fibers are the same as the fibers of the protruding fiber portions.

4. The absorbent article according to claim 1 or 2,

the pressure applied to the fibrous layer block was 25g/cm²The specific volume ratio is 0.2 or more and 0.7 or less.

5. The absorbent article according to claim 1 or 2,

the fibers constituting each of the plurality of block fibers are not thermally fused to each other.

6. The absorbent article according to claim 1 or 2,

when the ratio of the voids between the core portions in the block fiber layer is taken as the void ratio,

the pressure applied to the fibrous layer block was 3g/cm²The first porosity is 40% or more and 80% or less,

the pressure applied to the fibrous layer block was 25g/cm²The second porosity in the case of (3) is 2% or more and 60% or less.

7. The absorbent article according to claim 1 or 2,

the basis weight of the adhesive between the block fiber layer and the surface sheet is lower than the basis weight of the adhesive between the block fiber layer and the absorbent core.

8. The absorbent article according to claim 1 or 2,

at least a part of the surface sheet has a plurality of through-holes penetrating in the thickness direction toward the block fiber layer.

9. The absorbent article according to claim 1 or 2,

the block fibers are fiber balls.