Absorbent article

Abstract

To provide an absorbent article having good fitting property even when worn for a long time.SOLUTION: An absorbent article includes a top sheet, a back sheet, and an absorbent body disposed between the top sheet and the back sheet. The absorbent body includes an absorbent fiber layer located on a skin side and containing absorbent fibers, a compression restoration layer located on a non-skin side, a liquid retaining layer located closer to the non-skin side than the compression restoration layer, and a sheet member covering the absorbent fiber layer, the compression restoration layer, and the liquid retaining layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to absorbent articles such as sanitary napkins. [Background technology]

[0002] Absorbent articles such as disposable diapers and sanitary napkins generally comprise a topsheet that is positioned relatively close to the wearer's skin, a backsheet that is positioned relatively far from the wearer's skin, and an absorbent core interposed between the two sheets. This absorbent core is typically composed primarily of absorbent fibers such as wood pulp and often further contains a superabsorbent polymer. Absorbent cores used in absorbent articles are required to have improved properties such as flexibility, cushioning, compression recovery, and shape retention.

[0003] Patent Documents 1 and 2 describe the use of an absorbent core that contains fiber agglomerates containing synthetic fibers and absorbent fibers, with the mass ratio of the fiber agglomerates to the absorbent fibers being smaller on the skin-facing side than on the non-skin-facing side, in order to provide absorbent articles with both absorption performance and cushioning properties. The fiber agglomerates contribute to improving the flexibility, cushioning properties, compression recovery, shape retention, etc. of the absorbent core. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-98157 [Patent Document 2] Japanese Patent Application Publication No. 2020-96779 Summary of the Invention [Problem to be solved by the invention]

[0005] In absorbent articles that use fiber agglomerates that contribute to improving cushioning properties, compression recovery properties, etc., such as the absorbent articles of Patent Documents 1 and 2, when worn for a long period of time or when a large amount of excreted liquid is discharged in a short period of time, the liquid that cannot be contained by the upper absorbent fiber layer may reach the compression recovery layer located on the lower layer, which may reduce the cushioning properties of the compression recovery layer and tend to reduce the fit.

[0006] The object of the present invention is to provide an absorbent article that provides a good fit even when worn for a long period of time. [Means for solving the problem]

[0007] An absorbent article according to one aspect of the present invention includes a top sheet, a back sheet, and an absorbent body disposed between the top sheet and the back sheet. The absorbent body has an absorbent fiber layer containing absorbent fibers located on the skin side, a compression recovery layer located on the non-skin side, a liquid retention layer located on the non-skin side of the compression recovery layer, and a sheet member that encapsulates the absorbent fiber layer, the compression recovery layer, and the liquid retention layer. [Effects of the Invention]

[0008] The absorbent article of the present invention can provide an absorbent article that fits well even when a large amount of excrement is discharged in a short period of time or when worn for a long period of time. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view showing an absorbent article according to one embodiment of the present invention as viewed from the skin side. [Figure 2] FIG. 2 is a schematic cross-sectional view of the absorbent article taken along line II-II in FIG. [Figure 3] (A) and (B) are schematic perspective views of a fiber mass, and (C) is a schematic view of a fiber mass in an electron microscope photograph. [Figure 4] 4 is a schematic, partially enlarged cross-sectional view of the absorbent article taken along line IV-IV in FIG. 1. FIG. [Figure 5]FIG. 5 is a partially enlarged cross-sectional view of the absorbent article of the region enclosed by the dashed circle V in FIG. 4, and schematically shows the vicinity of the interface between the compression-recovery layer and the liquid-retaining layer. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, mutually orthogonal coordinate axes, that is, X-axis, Y-axis, and Z-axis, are appropriately shown. In the following description, the same reference numerals will be used for components that have already been mentioned, and the description may be omitted.

[0011] <Overall structure of absorbent article>

[0012] An absorbent article 1 according to one embodiment of the present invention is configured as a sanitary napkin and will be referred to hereinafter as the napkin 1. The napkin 1 has a longitudinal direction X corresponding to the front-to-back direction of the wearer and a transverse direction Y corresponding to the left-to-right direction of the wearer and perpendicular to the longitudinal direction X. The longitudinal direction X is the lengthwise direction of the napkin 1, and the transverse direction Y is the widthwise direction of the napkin 1. Furthermore, the napkin 1 has a thickness direction Z perpendicular to both the longitudinal direction X and the transverse direction Y. In this specification, with respect to the thickness direction Z, the side closer to the wearer's skin may be referred to as the upper or skin side, and the side closer to the underwear may be referred to as the lower or non-skin side. In this specification, the term "plan view" refers to a plan view seen from the thickness direction Z. In this specification, the term "outside in the transverse direction Y" refers to the side away from the longitudinal centerline CL that bisects the transverse direction Y of the napkin 1 in the transverse direction Y.

[0013] As shown in FIG. 1, the napkin 1 includes a main body M and a pair of wings W.

[0014] The main body M extends in a strip shape along the longitudinal direction X, and is fixed to the inner surface of the wearer's underwear when worn. The main body M is divided along the longitudinal direction X into a front region M1, a middle region M2, and a rear region M3. The middle region M2 includes an excretory part-facing region that faces the wearer's excretory part when worn. The excretory part-facing region is located at the center of the middle region M2 in the lateral direction Y. When the absorbent article is a napkin 1, the excretory part is the vaginal opening. The middle region M2 is the region where the wings W are provided. The front region M1 is a region that is disposed in front of the middle region M2 (on the wearer's ventral side) and faces the front of the wearer's excretory area when worn. The rear region M3 is a region that is disposed rearward of the middle region M2 (on the back side of the wearer), and faces the rear of the excretory parts of the wearer when worn. The term "when worn" as used herein means a state in which the normal, proper wearing position (the expected wearing position of the napkin 1) is maintained, and does not include a state in which the napkin 1 is shifted from that wearing position.

[0015] The main body M extends along the longitudinal direction X and is placed on the inner surface of the wearer's underwear. The main body M has the function of absorbing liquids (hereinafter also referred to as "liquid") such as menstrual blood of the wearer.

[0016] The pair of wings W extend outward in the lateral direction Y from the middle region M2 of the main body M. The wings W extend outward in the lateral direction Y from the underwear between the wearer's crotch, then fold inward and fasten to the outer surface of the underwear. This prevents the middle region M2 of the main body M from slipping out of the wearer's crotch.

[0017] The wings W are provided over the entire length in the longitudinal direction X in the middle region M2 of the main body M. In the napkin 1 according to this embodiment, the position of the middle region M2 in the main body M corresponds to the position of the wings W, and the middle region M2 is defined as the portion of the main body M where the wings W are provided. The front and rear ends of the wings W are the starting points for extension in the lateral direction Y at the front and rear, respectively, of the wings W.

[0018] As shown in Figures 1 and 2, the napkin 1 comprises a topsheet 2, an absorbent body 4, a backsheet 3, and a pair of sidesheets 9. In the main body M, the napkin 1 has a configuration in which the backsheet 3, absorbent body 4, and topsheet 2 are laminated in the thickness direction Z. These components are joined together as appropriate by, for example, a pair of central compressed grooves 20, a front lateral compressed groove 31, a first rear compressed groove 32, and a second rear compressed groove 33, which are formed by bonding with an adhesive or heat sealing, or by compression processing, as shown in Figure 1. Note that the compressed grooves are not shown in Figure 2.

[0019] The top sheet 2 is disposed above the absorbent body 4 in the thickness direction Z. A pair of side sheets 9 extend in the longitudinal direction X and are disposed on both left and right sides of the top sheet 2. The side sheets 9 are provided on both left and right sides of the main body M and across the wings W. The side sheets 9 are joined to the top sheet 2, for example, by an adhesive 12. The back sheet 3 is disposed below the absorbent body 4 in the thickness direction Z. The back sheet 3 is provided across the entire main body M and wings W. Both the top sheet 2 and the side sheets 9 are located on the back sheet 3. The back sheet 3 is joined to the top sheet 2 and the side sheets 9, for example, at its periphery, by an adhesive, heat sealing, etc. The back sheet 3 is provided with adhesive portions 10 and 11 for fixing the main body M and wings W to the underwear.

[0020] The top sheet 2 is made of a highly liquid-permeable sheet material so that it can efficiently absorb liquids such as menstrual blood from the top surface. On the other hand, the back sheet 3 and side sheets 9 are made of a less liquid-permeable sheet material so that liquids absorbed from the top sheet 2 do not easily leak out. The top sheet 2, back sheet 3, and side sheets 9 can be made of materials similar to those conventionally used in the relevant technical field, without any particular limitations. For example, the top sheet 2 can be made of a liquid-permeable nonwoven fabric, a perforated film, or a sheet containing natural fibers such as cotton. The back sheet 3 can be made of a liquid-impermeable film made of synthetic resin, or a water-repellent nonwoven fabric with high water pressure resistance, such as a spunbond-meltblown-spunbond laminated nonwoven fabric. The side sheets 9 can be made of a water-repellent nonwoven fabric with high water pressure resistance, such as a spunbond-meltblown-spunbond laminated nonwoven fabric.

[0021] The absorbent body 4 extends in the longitudinal direction X and is disposed between the topsheet 2 and the backsheet 3. The absorbent body 4 absorbs liquid from the surface facing the topsheet 2 and diffuses the liquid internally to retain it. The absorbent body 4 of this embodiment is capable of retaining liquid and maintaining a good fit even after the liquid has been retained after wearing. The absorbent body 4 will be described below.

[0022] <Absorbent structure>

[0023] As shown in Figure 2, the absorbent body 4 comprises an absorbent fiber layer 7, a compressed and resilient layer 8, a liquid retaining layer 5, and a core wrap sheet 6. In the absorbent body 4, the absorbent fiber layer 7 is located on the skin side. The compressed and resilient layer 8 is located on the non-skin side. The liquid retaining layer 5 is located on the non-skin side of the compressed and resilient layer 8. In the absorbent body 4, the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5 are arranged in this order from the skin side to the non-skin side. Note that in Figure 2, the peripheries of the absorbent fiber layer 7 and the compressed and resilient layer 8 are each depicted as being surrounded by a solid line, but this is merely a line drawn to clearly show the extent of each layer and does not represent a specific component. Furthermore, although it is depicted as if there are gaps between both sides of the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5 in the lateral direction Y and the core wrap sheet 6, this is depicted for convenience to clearly show the relationship between each layer and the core wrap sheet 6; in reality, no gaps exist.

[0024] The absorbent fiber layer 7 primarily contributes to absorbing and retaining liquid. The compressed and resilient layer 8 contributes to improving the flexibility, cushioning, compression recovery, and shape retention of the absorbent body 4. The liquid retaining layer 5 is a layer that can absorb and retain liquid that has permeated the absorbent fiber layer 7 and the compressed and resilient layer 8 and reached the liquid retaining layer 5, making it difficult for liquid to accumulate in the compressed and resilient layer 8. The compressed and resilient layer 8 has an extremely low liquid absorption and retention capacity compared to the absorbent fiber layer 7, thereby ensuring the above-mentioned effects. The liquid retaining layer 5 prevents a decrease in cushioning and compression recovery due to liquid accumulation (hereinafter sometimes referred to as "retention") in the compressed and resilient layer 8, contributing to the maintenance of a good fit. The core wrap sheet 6 contributes to the shape retention of the absorbent body 4 by stably maintaining the laminated state of the absorbent fiber layer 7, compressed and resilient layer 8, and liquid retaining layer 5, and improves liquid migration between the layers within the absorbent body 4. Each component is described in detail below.

[0025] [Absorbent fiber layer] As shown in Fig. 1, the absorbent fiber layer 7 is elongated in the longitudinal direction X in plan view, and its longitudinal direction coincides with the longitudinal direction X of the napkin 1. The width direction of the napkin 1 coincides with the lateral direction Y. In this embodiment, the absorbent fiber layer 7 has a shape with a uniform width over the entire length in the longitudinal direction X. The outer shape of the absorbent fiber layer 7 in plan view is the same as that of the absorbent body 4.

[0026] The absorbent fiber layer 7 contains a water-absorbent material and absorbs and retains liquid. Examples of water-absorbent materials include water-absorbent fibers and superabsorbent polymers, and these can be used alone or in combination of two or more. Examples of water-absorbent fibers include natural fibers such as wood pulp and hydrophilic fibers such as hydrophilic synthetic fibers. The superabsorbent polymer can be the same as the one described below in "Configuration of the Liquid Retention Layer," and any polymer conventionally used in this type of absorbent can be used without particular limitation, such as a polymer or copolymer of acrylic acid or an alkali metal acrylate.

[0027] The absorbent fiber layer 7 may be of either a stacked fiber type or a sheet type. A stacked fiber type absorbent core typically comprises an aggregate of fibrous materials such as absorbent fibers, with superabsorbent polymer particles optionally supported on the aggregate. The stacked fiber type absorbent fiber layer 7 can be manufactured by a conventional method using a known fiber stacking device equipped with a rotating drum. On the other hand, a sheet type absorbent core typically comprises a fiber sheet having superabsorbent polymer particles fixed to the interior or surface thereof, and is also called a water-absorbent sheet. Examples of the fiber sheet include paper and nonwoven fabric. A sheet type absorbent core is thinner and more flexible than a stacked fiber type absorbent fiber layer. A sheet type absorbent fiber layer may, for example, comprise two opposing fiber sheets with superabsorbent polymer particles interposed between them.

[0028] 2, the absorbent fiber layer 7 includes absorbent fibers 70 and a superabsorbent polymer 71. The superabsorbent polymer 71 may be the same as the superabsorbent polymer 51 contained in the liquid retention layer 5 described below.

[0029] Any absorbent fiber conventionally used as a material for forming an absorbent body in this type of absorbent article can be used as the absorbent fiber 70. Examples of absorbent fibers include natural fibers such as wood pulp, such as softwood pulp or hardwood pulp, and non-wood pulp, such as cotton pulp or hemp pulp; modified pulp, such as cationized pulp or mercerized pulp; and regenerated fibers, such as cupra or rayon. These fibers can be used alone or in combination of two or more.

[0030] [Compression and decompression layer] The compression-resilient layer 8 is a layer that deforms to reduce its thickness when an external force is applied and to increase its thickness when the external force is removed, preferably to return to its original thickness. In this embodiment, the compression-resilient layer 8 has higher compression-resilience than the absorbent fiber layer 7. Because of its high compression-resilience, the compression-resilient layer 8 generates a force that attempts to restore the original shape before compression even when compressive pressure is applied in the thickness direction Z from the wearer during wear, making it easier for the napkin 1 to deform so as to reduce the likelihood of gaps forming between the wearer's skin and the napkin 1. This makes it less likely for gaps to form between the wearer's skin and the napkin 1, even under conditions where gaps are typically formed between the napkin and the wearer's body, such as during strenuous exercise or when worn for long periods of time, due to the compression-resilience of the compression-resilient layer 8. This improves the fit to the wearer's skin and effectively prevents liquid leakage. Compression-resilience will be described later.

[0031] (Planar view of the compression recovery layer) As shown in Fig. 2, the compressed and resilient layer 8 is disposed below and in contact with the absorbent fiber layer 7. From the viewpoint of a comfortable fit, it is preferable that the compressed and resilient layer 8 be provided only in the middle region M2 (the central region in the longitudinal direction X) in a plan view, as shown in Fig. 1. With this configuration, during daytime use of the napkin 1, pressure from the wearer is likely to be applied to the middle region M2, including the region facing the excretory area (the central portion of the middle region M2 in the transverse direction Y). Therefore, the compressive and resilient properties of the compressed and resilient layer 8 improve the fit to the skin, providing a comfortable fit. Furthermore, by not providing a compressed and resilient layer in the front region M1 and rear region M3, an increase in thickness due to the placement of a compressed and resilient layer can be avoided, and the napkin 1 does not become stiff due to an increase in thickness in the front and rear regions, resulting in a comfortable fit in the front and rear regions. Furthermore, a step is created in the absorbent core 4 near the boundary between the areas where the compressed and resilient layer 8 is present and the areas where it is not present. As a result, the front region M1 of the napkin 1 tends to bend from the front step toward the wearer's stomach, and the rear region M3 tends to bend from the rear step toward the wearer's back, making it easier for the napkin 1 to deform along the shape of the wearer's body and fit the body better.

[0032] 2, the compression-recovery layer 8 is preferably disposed at least in the center in the lateral direction Y so as to face the wearer's excretory area, and in particular, it preferably has substantially the same dimension (width) as the absorbent fiber layer 7 in the lateral direction Y and overlaps the absorbent fiber layer 7 in the lateral direction Y. This makes it less likely that gaps will form between the wearer's skin and the napkin 1 throughout the entire intermediate region M2, where a particularly large amount of liquid is supplied, due to the compression-recovery properties of the compression-recovery layer 8, improving the fit to the wearer's skin and effectively suppressing liquid leakage.

[0033] The constituent fibers of the compressed and resilient layer 8 may be contained in small amounts in the front region M1 and / or the rear region M3. In this embodiment, the compressed and resilient layer 8 is formed using fiber agglomerates, which are fiber aggregates in which a plurality of constituent fibers are integrated together, as will be described in detail later. The compressed and resilient layer 8 can be formed, for example, by accumulating fiber agglomerates using a fiber stacking device. During the formation of the compressed and resilient layer, a small amount of fiber agglomerates may unintentionally accumulate in the front region M1 and / or the rear region M3. Thus, even if a small amount of fiber agglomerates 80 is contained in the front region M1 and / or the rear region M3, a comfortable wearing experience can be achieved. When the compression-recovery layer 8 is measured in the "Method for Measuring the Water Retention Rate of a Liquid Retaining Layer" described below, substituting "Liquid Retaining Layer" for "Compression-recovery Layer," the water retention rate is preferably 8% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less.

[0034] (fiber mass) As shown in FIG. 2, the compression-resilience layer 8 can be configured to include, for example, a plurality of entangled fiber agglomerates 80. The fiber agglomerates 80 are primarily composed of hydrophobic fibers, have a low density, a porous structure, and excellent liquid permeability. When measuring the moisture content of a liquid-retaining layer (described later) by substituting "fiber agglomerates" for "liquid-retaining layer," the hydrophobic fibers preferably have a moisture content of 3% or less, and particularly 1% or less. When "substituting fiber agglomerates" is used, if the fiber agglomerates are too small to measure their moisture content, they may be measured as an aggregate of multiple fiber agglomerates. For example, multiple fiber agglomerates weighing approximately 5 g may be collected and used to measure their moisture content. As shown in FIG. 3(C), the fiber agglomerates 80 are fiber aggregates formed by intentionally accumulating multiple fibers 83 into an integrated aggregate. The fiber agglomerates 80 can exist in the compression-recovery layer 8 while maintaining the fiber aggregate shape. The fiber agglomerates 80 primarily contribute to improving the flexibility, cushioning, compression-recovery, and shape retention of the compression-recovery layer 8 and, ultimately, the absorbent core 4.

[0035] The fiber agglomerates 80 may take the form of, for example, sheet pieces separated from a synthetic fiber sheet of a certain size. In particular, a nonwoven fabric is selected as the synthetic fiber sheet, and the fiber agglomerates are preferably nonwoven fabric pieces cut into a predetermined size and shape from the nonwoven fabric. Such sheet-piece-shaped fiber agglomerates are not formed by gathering multiple fibers together to form the sheet pieces, but are produced by cutting a fiber sheet (preferably nonwoven fabric) that is larger in size than the sheet pieces. The multiple fiber agglomerates 80 contained in the compression-recovery layer 8 are multiple fiber agglomerates with high definite shape.

[0036] 3(A) and (B) show typical external shapes of a fiber agglomerate 80. The fiber agglomerate 80A shown in FIG. 3(A) has a quadrangular prism shape, more specifically, a rectangular parallelepiped shape, while the fiber agglomerate 80B shown in FIG. 3(B) has a disk shape. The fiber agglomerates 80A and 80B have in common the fact that they have two opposing basic surfaces 82 and a skeletal surface 81 connecting the two basic surfaces 82. Both the basic surface 82 and the skeletal surface 81 are portions that are recognized as having substantially no irregularities at the level applied when evaluating the degree of surface irregularities in an article mainly made of this type of fiber.

[0037] The rectangular parallelepiped fiber mass 80A in Fig. 3(A) has six flat surfaces, of which two opposing surfaces with the largest areas are basic surfaces 82, and the remaining four surfaces are skeletal surfaces 81. The basic surfaces 82 and the skeletal surfaces 81 intersect with each other, more specifically, are perpendicular to each other. The basic surfaces 82 are preferably in the shape of a rectangle or a parallelogram, but it is preferable that the four sides constituting the basic surfaces 82 have the same length, and it is particularly preferable that the basic surfaces 82 are square.

[0038] The disk-shaped fiber mass 80B in Fig. 3(B) has two opposing flat surfaces that are circular in plan view and a curved peripheral surface that connects the two flat surfaces, and the two flat surfaces are basic surfaces 82 and the peripheral surface is a skeletal surface 81. The basic surface 82 and the skeletal surface 81 intersect with each other, more specifically, are perpendicular to each other.

[0039] In order to prevent liquid from accumulating in the compression recovery layer 8 and maintain good compression recovery even after the napkin has been worn, it is preferable that the compression recovery layer 8 be mainly composed of fiber agglomerates 80 composed mainly of hydrophobic fibers, and it is even more preferable that the compression recovery layer 8 be composed solely of fiber agglomerates.

[0040] Fiber agglomerates 80A and 80B are also common in that their skeletal surfaces 81 have a quadrangular shape, more specifically, a rectangular shape, in plan view. The multiple fiber agglomerates 80 contained in the compression-recovery layer 8 are each a "fixed-shape fiber aggregate" having two opposing base surfaces 82 and a skeletal surface 81 connecting the two base surfaces 82, such as fiber agglomerates 80A and 80B shown in Figure 3. Such a "fixed-shape fiber aggregate" improves the uniform dispersion of the fiber agglomerates 80 in the compression-recovery layer 8, and therefore the effects described by using the fiber agglomerates 80 (such as improved flexibility, cushioning, and compression recovery of the absorbent) are stably achieved. In particular, in the case of a rectangular parallelepiped fiber agglomerate 80A as shown in Figure 3(A), its outer surface consists of six surfaces, two basic surfaces 82 and four skeletal surfaces 81, so that compared to a disk-shaped fiber agglomerate 80B having three outer surfaces as shown in Figure 3(B), it is possible for the fiber agglomerate to have relatively more opportunities for contact with other fiber agglomerates, which increases entanglement and may also lead to improved shape retention, etc.

[0041] The two types of surfaces (basic surface 82, skeletal surface 81) possessed by fiber agglomerates 80 (80A, 80B) are classified into cut surfaces (skeletal surface 81) formed by cutting the raw fiber sheet with a cutting means such as a cutter when producing fiber agglomerates 80, and uncut surfaces (basic surface 82) that are inherent surfaces of the raw fiber sheet and do not come into contact with the cutting means. Due to the difference between being a cut surface and not being a cut surface, the skeletal surface 81, which is a cut surface, has a greater number of fiber ends 84 per unit area (see FIG. 3(C)) than the basic surface 82, which is an uncut surface.

[0042] The fiber ends 84 present on each surface (basic surface 82, skeletal surface 81) of the fiber agglomerates 80 are effective in entangling the fiber agglomerates 80 with other fiber agglomerates 80 contained in the compressed and recoverable layer 8. Generally, the greater the number of fiber ends 84 per unit area, the better the entanglement, which can lead to improvements in various properties such as the shape retention of the compressed and recoverable layer 8. The number of fiber ends 84 per unit area on each surface of the fiber agglomerates 80 is not uniform, and there is a size relationship of "skeletal surface 81 > basic surface 82" regarding the number of fiber ends 84 per unit area. Therefore, the degree of entanglement with other fiber agglomerates 80 via the fiber agglomerates 80 varies depending on the surface of the fiber agglomerates 80, with the skeletal surface 81 having a higher entanglement degree than the basic surface 82. In other words, the bonding strength through entanglement with other fiber agglomerates 80 via the skeletal surface 81 is stronger than that through the basic surface 82, and within a single fiber agglomerate 80, there may be a difference in the bonding strength with other fiber agglomerates 80 between the basic surface 82 and the skeletal surface 81.

[0043] In this way, each of the multiple fiber agglomerates 80 contained in the compressed and resilient layer 8 is entangled with the surrounding fiber agglomerates 80 by two types of bonding force, which gives the compressed and resilient layer 8 both moderate softness and strength (shape retention). When the compressed and resilient layer 8 having such excellent properties is used in the usual manner as part of the absorbent body of an absorbent article, it can provide a comfortable fit to the wearer of the absorbent article and effectively prevent the compressed and resilient layer 8 from being destroyed by external forces such as the pressure exerted by the wearer when wearing the article.

[0044] In particular, the fiber agglomerates 80 (80A, 80B) shown in Figures 3(A) and (B) have a flat shape, and the total area of ​​the two basic faces 82 is larger than the total area of ​​the skeletal face 81. For this reason, the basic faces 82, which have a relatively small number of fiber ends per unit area and therefore a relatively low tendency to entangle with other fiber agglomerates, have a larger total area than the skeletal face 81, which has the opposite property. Therefore, the fiber agglomerates 80 (80A, 80B) shown in Figures 3(A) and (B) are more likely to be prevented from entangling with other surrounding fiber agglomerates than fiber agglomerates in which fiber ends 84 are uniformly distributed over the entire surface. Even if they are entangled with other surrounding fiber agglomerates, they are likely to be entangled with relatively weak bonding forces. Therefore, they are less likely to form large agglomerates, and this can impart excellent flexibility to the compression-recovery layer 8.

[0045] Thus, the fiber agglomerates 80 have excellent flexibility and other properties. In addition to containing such fiber agglomerates 80 in the compression-recovery layer 8, the fiber agglomerates 80 are bonded to each other by entanglement with a relatively weak bonding force, so that the compression-recovery layer 8 has even better responsiveness to external forces and is excellent in flexibility, cushioning, and compression recovery. When such a compression-recovery layer 8 is incorporated into an absorbent article, it flexibly deforms in response to external forces applied from various directions (for example, body pressure of the wearer of the absorbent article), allowing the absorbent article to fit closely to the wearer's body. Such excellent deformation-recovery properties of the compression-recovery layer 8 are exhibited not only when the compression-recovery layer 8 is compressed, but also when it is twisted. That is, the compression-recovery layer 8 incorporated in the napkin 1 is positioned between the wearer's thighs when the napkin 1 is worn, and therefore the compression-recovery layer 8 may be twisted around a virtual axis of rotation extending in the vertical direction X due to the movement of the wearer's thighs when walking. However, even in such cases, the compression-recovery layer 8 has high deformation-recovery properties, so it easily deforms and recovers in response to external forces that would cause twisting from the thighs, and is therefore less likely to become twisted, allowing the napkin 1 to fit the wearer's body well.

[0046] (Modification of compression and recovery layer) The compression and recovery layer 8 may contain a small amount of superabsorbent polymer in addition to the fiber agglomerates 80. This is because the fibers constituting the fiber agglomerates 80 are hydrophobic, and the superabsorbent polymer does not quickly absorb electrolyte-containing excreted fluids, particularly highly viscous fluids such as menstrual blood, so that the compression and recovery layer 8 has the property of being less likely to retain liquid. However, the superabsorbent polymer should be contained within a range that does not impair the effect of less liquid retention in the compression and recovery layer 8. When a superabsorbent polymer is contained, it is preferable to adjust the amount of superabsorbent polymer so that the following conditions 1 to 3 are satisfied.

[0047] Condition 1: The content of the superabsorbent polymer must be within a range that does not impair the liquid permeability of the compression-recovery layer 8. In other words, the compression-recovery layer 8 has a low density and a void structure, and since this void structure affects the liquid permeability, cushioning properties, and compression-recovery properties, by distributing a small amount of superabsorbent polymer so as not to fill the voids, the liquid permeability, cushioning properties, and compression-recovery properties are less likely to be impaired.

[0048] Condition 2: The basis weight of the superabsorbent polymer 71 contained in the absorbent fiber layer 7 is greater than the basis weight of the superabsorbent polymer contained in the compression-recovery layer 8. When the compression-recovery layer 8 contains a superabsorbent polymer, the basis weight of the superabsorbent polymer 71 contained in the absorbent fiber layer 7 in the area where the absorbent fiber layer 7 and the compression-recovery layer 8 overlap in plan view is at least 20 times, and preferably at least 50 times, the basis weight of the superabsorbent polymer contained in the compression-recovery layer 8.

[0049] Condition 3: The relationship between the liquid diffusibility measured by the liquid diffusibility measurement method described later is The compression recovery layer must be less than the liquid retention layer and absorbent fiber layer.

[0050] (Another example of the compression / decompression layer configuration) In this embodiment, a fiber mass is used to impart compression recovery to the compression-recovery layer 8, but this is not limiting. For example, a nonwoven fabric having a fiber layer containing urethane foam or crimped fibers may be used to provide a layer with higher compression recovery than the absorbent fiber layer 7. Examples of the crimped fibers include mechanically crimped fibers that are two-dimensionally crimped into a zigzag pattern, three-dimensionally crimped fibers that are three-dimensionally crimped into a spiral pattern, and latent crimped fibers that are three-dimensionally crimped into a coil pattern by applying heat. Examples of crimped fibers include eccentric core-sheath or side-by-side composite fibers composed of two thermoplastic polymer materials with different shrinkage rates. More specifically, examples include those described in JP-A-9-296325, Japanese Patent No. 2759331, and Japanese Patent No. 5404967.

[0051] (Method for measuring liquid diffusibility) The napkin was placed on a flat table with the topsheet facing upward. An acrylic liquid injection plate was placed on top of the topsheet. The plate consisted of an integrally molded cylinder with a diameter of 10 mm and a height of 50 mm, and a 200 mm x 100 mm plate with a bottom and an injection hole at the position where the cylinder would be placed. 1 g of colored saline was injected into the cylinder and left for 1 minute to be absorbed into the napkin. The liquid injection plate was then removed, and the areas of the colored regions formed by the injection of saline in the absorbent fiber layer, compression recovery layer, and liquid retention layer were measured, and this area was taken as the liquid diffusion area. The liquid diffusion area was calculated by graphic processing of an image of the colored region read by a scanner. It can be determined that the larger the liquid diffusion area, the higher the liquid diffusibility.

[0052] (Regarding compression recovery) Compression recovery can be evaluated using the compression work (hereinafter also referred to as "WC") and recovery work (hereinafter also referred to as "WC'"). WC is an index of the cushioning properties of the object being measured (here, the absorbent fiber layer, the compressed and recovered layer). The larger the WC value, the better the cushioning of the object being measured, and therefore the better the compression recovery. WC' is an index of the recovery (compression recovery) of the object being measured when an external force is applied to the object to compress it and then the external force is removed. The larger the WC' value, the better the compression recovery of the object being evaluated. WC and WC' are measured using the following methods. Note that "the compressed and recovered layer has higher compression recovery than the absorbent fiber layer" means that both WC and WC' of the compressed and recovered layer 8 are greater than those of the absorbent fiber layer 7.

[0053] ((Method of measuring compression work (WC) and recovery work (WC')) It is generally known that the WC and WC' to be measured can be expressed as the measured values ​​using the KES (Kawabata Evaluation System) manufactured by Kato Tech Co., Ltd. (Reference: Standardization and Analysis of Texture Evaluation (2nd Edition), author Kawabata Takao, published July 10, 1980). Specifically, WC and WC' can be measured using the KES-G5 compression testing device manufactured by Kato Tech Co., Ltd. The measurement procedure is as follows:

[0054] First, a sample is attached to the test stand of the compression tester. The sample is, for example, a component of an absorbent article such as a napkin 1 (for example, an absorbent fiber layer 7 or a compression recovery layer 8). The sample is in a dry state and has a rectangular shape in plan view, measuring 5 mm in length and 5 mm in width. If the dry sample is the absorbent fiber layer 7 or the compression recovery layer 8 contained in an absorbent body, the absorbent body is unused, has not absorbed any liquid, and is in a dry state. Next, the sample is placed on a piece of paper with an area of ​​2 cm. 2 The specimen is compressed between steel plates with circular flat surfaces. The part to be compressed is the non-concave part of the specimen, i.e., the part that has not been subjected to compression processing and retains its original shape. The compression speed is 0.2 cm / sec, and the maximum compression load is 2450 mN / cm. 2, SENS is 10, and DEF is 20. The restoration process is also measured at the same speed. WC is expressed by the following formula (1), and WC' is expressed by the following formula (2), and the units are "mN / cm / cm" 2 " In the following formula, T m is 2450mN / cm 2 Thickness under load (4.9 kPa), T o is 4.902mN / cm 2 (49 Pa). In addition, Pa in the following formula (1) and Pb in the following formula (2) respectively represent the measurement load (mN / cm) during the compression process. 2 ), measurement load during thickness restoration process (mN / cm 2 ) is shown.

[0055]

number

[0056]

number

[0057] Note that WC' is not displayed on the measurement result screen of the KES-G5, but rather, what is displayed on the measurement result screen is WC and the compression recovery rate or compression resilience (hereinafter also referred to as "RC") calculated from WC'. In such cases, WC' is calculated using the parameters (WC, RC) displayed on the measurement device using the following formula (3).

[0058]

number

[0059] [Liquid retention layer] The liquid retaining layer 5 has the function of absorbing and retaining the wearer's liquid that has permeated through the compression and recovery layer 8.

[0060] The liquid retaining layer 5 is a layer having a moisture content of 6% or more, measured by the method described below, which indicates the degree of water absorbency, and a moisture retention rate, which indicates the degree of liquid retention, of 10% by mass or more. A moisture content of 6% or more indicates high liquid absorption ability. A moisture retention rate of 10% by mass or more indicates high liquid retention performance. The moisture content and moisture retention rate of the liquid retaining layer 5 are preferably 8% or more and 12% by mass or more, and particularly preferably 10% or more and 15% by mass or more.

[0061] (Method for measuring moisture content of liquid retaining layer) In this specification, the term "water absorbency" is easily understood by those skilled in the art, for example, by the fact that pulp is water absorbent. The degree of water absorbency of the liquid-retaining layer can also be determined by the value of its moisture content measured by the following method.

[0062] The method for measuring the moisture content will be described below. The moisture content was calculated according to the moisture content test method of JIS P8203. Specifically, the sample was left to stand for 24 hours in a test room at a temperature of 40°C and a relative humidity of 80% RH, and then the mass a (g) of the sample before the bone-drying treatment was measured in the same room. The sample was then placed in an electric dryer (e.g., manufactured by Isuzu Motors Co., Ltd.) at a temperature of 105±2°C for 1 hour to bone-dry the sample. After the bone-drying treatment, the fiber sample was wrapped in Saran Wrap (registered trademark) manufactured by Asahi Kasei Corporation and placed in a glass desiccator (e.g., manufactured by Techjam Co., Ltd.) under standard conditions of a temperature of 20±2°C and a relative humidity of 65±2%. The fiber sample was then weighed to a constant mass b (g), and the moisture content (mass fraction) of the sample was calculated using the following formula: Moisture percentage (%)={(ab) / b}×100

[0063] (Method for measuring water retention rate of liquid-retaining layer) The water retention rate of the liquid retaining layer 5 can be measured by the following method. Specifically, the liquid retaining layer to be measured is removed. The liquid retaining layer to be measured is then cut into a 100 mm square sample, and its mass m1 (g) is measured. These procedures are carried out in an environment with a temperature of 22±2°C and a humidity of 50±2% RH. Next, the sample was immersed in saline under the above conditions for 2 minutes, then removed and hung for 10 minutes. The mass of the sample, m2 (g), was then measured. The increase in mass before and after immersion (m2 - m1) was divided by the mass of the sample before immersion, m1, and multiplied by 100 to obtain the water retention rate (% by mass). The higher the water retention rate, the higher the liquid retention capacity.

[0064] (Configuration of liquid retaining layer) As shown in FIGS. 2 and 4, in this embodiment, the liquid retaining layer 5 is composed of a water-absorbent sheet 52 and a plurality of highly water-absorbent polymers 51 arranged on the skin-facing side of the water-absorbent sheet 52.

[0065] ((Superabsorbent polymer)) The superabsorbent polymer 51 is a surface-crosslinked polymer material known as a SAP (Super Absorbent Polymer), and has excellent water absorption and liquid retention properties. The superabsorbent polymer 51 absorbs and retains liquid that reaches the liquid retention layer 5. From the viewpoint of good liquid absorption and retention over the entire surface of the liquid retention layer 5, the superabsorbent polymer 51 is preferably disposed over the entire surface of the water-absorbent sheet 52.

[0066] As the superabsorbent polymer, particulate polymers are generally used, but fibrous polymers may also be used. When particulate superabsorbent polymers are used, their shape may be any of spherical, block, bale-like, or amorphous. As the superabsorbent polymer, generally, polymers or copolymers of acrylic acid or alkali metal acrylates can be used. Examples include polyacrylic acid and its salts, and polymethacrylic acid and its salts. As the polyacrylates and polymethacrylates, sodium salts can be preferably used.

[0067] ((Water-absorbent sheet)) The absorbent sheet 52 may be a sheet containing absorbent fibers as its main component. Here, "containing absorbent fibers as its main component" means that absorbent fibers account for the largest proportion by mass of the components constituting the absorbent sheet 52, preferably at least 50% by mass, more preferably at least 75% by mass, and particularly preferably 100% by mass. The absorbent sheet 52 absorbs and retains liquid that has passed through the compression recovery layer and reached the liquid retention layer 5. The absorbent sheet 52 also has high liquid diffusibility, diffusing liquid in the in-plane direction of the sheet. The absorbent sheet 52 may be the same as the core wrap sheet 6, for example. Paper or pulp sheets made from hydrophilic fibers, hydrophilic nonwoven fabrics, etc., made from hydrophilic fibers, may also be used as the absorbent sheet.

[0068] The absorbent sheet 52 absorbs and retains liquid, and also contributes to the in-plane diffusion of liquid in the liquid retention layer 5. Furthermore, the absorbent sheet 52 prevents scattering of the fiber agglomerates 80 that make up the compressed and recoverable layer 8 during the production of the absorbent body 4, and also prevents scattering of the superabsorbent polymer 51.

[0069] (Function of the liquid retention layer) In the napkin 1 of this embodiment, liquid that migrates from the compressed and restored layer 8 to the liquid-retaining layer 5 first comes into contact with the superabsorbent polymer 51 located above the absorbent sheet 52. The absorption rate of the superabsorbent polymer 51 is not dramatically fast, and viscous liquids such as menstrual blood are difficult to rapidly absorb by the superabsorbent polymer 51. Therefore, liquid that migrates from the compressed and restored layer 8 and is not immediately absorbed by the superabsorbent polymer 51 reaches the absorbent sheet 52 located below the superabsorbent polymer 51 and is diffused in the plane of the absorbent sheet 52. During this diffusion, the superabsorbent polymer 51 located above the absorbent sheet 52 draws the liquid within the absorbent sheet 52 from the area where it is in contact with the absorbent sheet 52, absorbing and retaining the liquid. The absorbent sheet 52 is responsible for diffusing the liquid in the plane as well as absorbing and retaining the liquid. If the liquid-retaining layer 5 does not contain a superabsorbent polymer, the liquid is diffused and retained within the plane of the absorbent sheet 52. For products that are not designed to retain large amounts of body fluids, such as daytime napkins for light incontinence days or light incontinence pads, it is advantageous from the standpoint of manufacturing costs not to include a highly absorbent polymer in the liquid retention layer 5. In addition, this is useful in situations where such absorbent articles must be worn for longer periods than expected or when larger amounts of body fluids than expected are excreted.

[0070] In this way, the liquid retaining layer 5 is provided below the compression-resilience layer 8, and the liquid that has permeated the compression-resilience layer 8 is absorbed and retained by the liquid retaining layer 5, thereby preventing liquid from pooling in the compression-resilience layer 8. This prevents a decrease in cushioning properties and compression-resilience due to liquid pooling in the compression-resilience layer 8, and allows the compression-resilience layer 8 to maintain good compression-resilience over time from the initial wearing stage, ensuring a sustained good fit to the wearer even when worn for extended periods of time.

[0071] (Another example of a liquid retaining layer) In this embodiment, an example has been given in which the liquid retaining layer 5 is composed of a water-absorbent sheet 52 and a plurality of highly water-absorbent polymers 51 arranged on the skin-side surface of the water-absorbent sheet 52, but the present invention is not limited to such a configuration.

[0072] For example, the liquid retaining layer may be a laminated structure in which multiple superabsorbent polymers are supported between two absorbent sheets, a mixed stack of hydrophilic fibers and superabsorbent polymers, or a stack of absorbent fibers. The liquid retaining layer may also be composed of an absorbent sheet and multiple superabsorbent polymers arranged on the non-skin-contact side of the absorbent sheet. However, from the perspective of effectively suppressing the scattering of superabsorbent polymers during manufacturing, it is preferable that the superabsorbent polymer be arranged on the skin-contact side of the absorbent sheet, as in this embodiment. The liquid retaining layer may also be composed of only an absorbent sheet, or may be composed of a superabsorbent polymer stack consisting solely of superabsorbent polymers.

[0073] From the viewpoint of spreading the liquid within the plane of the liquid retaining layer and absorbing and retaining it over a wide area, it is preferable that the absorbent fibers are present throughout the plane of the liquid retaining layer. By using absorbent fibers, the liquid is spread within the plane of the liquid retaining layer, allowing the liquid to be absorbed and retained over a wide area, preventing the accumulation of liquid within the compression and recovery layer 8, and maintaining a good fit to the wearer.

[0074] From the viewpoint of improving the liquid retention capacity of the liquid retention layer, it is preferable that the liquid retention layer contains a highly water-absorbent polymer. By using a highly water-absorbent polymer, the liquid retention ability of the liquid retention layer can be improved, and the accumulation of liquid in the compressed and recoverable layer 8 can be more reliably suppressed, thereby maintaining a good fit to the wearer.

[0075] From the viewpoint of improving the liquid retention capacity while absorbing the liquid by spreading it over a wide area within the plane of the liquid retention layer, it is even more preferable that the liquid retention layer has absorbent fibers (in this embodiment, an absorbent sheet) and a highly absorbent polymer present throughout the plane of the liquid retention layer, as in the liquid retention layer 5 of this embodiment. With this configuration, the absorbent fibers allow liquid to be dispersed in the plane of the liquid retaining layer, and the highly absorbent polymer can then absorb and fix the liquid, thereby more significantly suppressing the accumulation of liquid within the compressed and recoverable layer 8 and maintaining a good fit to the wearer even when worn for long periods of time.

[0076] In addition, configurations in which absorbent fibers and superabsorbent polymers are present across the surface of the liquid retention layer include a configuration in which superabsorbent polymer 51 is arranged on one side of absorbent sheet 52 as in this embodiment, as well as a laminated structure in which multiple superabsorbent polymers are supported between two absorbent sheets, and a mixed stack of hydrophilic fibers and superabsorbent polymers.

[0077] (Detailed structure of the liquid retention layer) When the liquid retention layer is configured to include a water-absorbent sheet 52 and a highly water-absorbent polymer 51, as in the liquid retention layer 5 of this embodiment, it is preferable that the water-absorbent sheet and the highly water-absorbent polymer are not bonded together by an adhesive such as a hot-melt adhesive. Since the superabsorbent polymer 51 is not bonded to the absorbent sheet 52, swelling of the superabsorbent polymer 51 due to liquid absorption is not inhibited, and the superabsorbent polymer is able to absorb and retain liquid well. As a result, the effect of suppressing liquid accumulation in the compressed and recoverable layer 8 can be more efficiently exerted, and a good fit to the wearer can be maintained.

[0078] (Planar view shape of liquid retention layer) In the napkin 1 of this embodiment, the compressed and resilient layer 8 and the liquid retaining layer 5 each have a shape with a uniform width over the entire length in the longitudinal direction X. In order to efficiently suppress liquid retention in the compressed and resilient layer 8 in the napkin 1, in a plan view, the liquid retaining layer 5 overlaps with the compressed and resilient layer 8 over a length in the transverse direction Y that is preferably 75% or more of the dimension (width) of the compressed and resilient layer 8 in the transverse direction Y, more preferably 90% or more, and particularly preferably 100%. In this embodiment, the widths of the liquid retaining layer 5 and the compressed and resilient layer 8 are approximately the same, and they overlap almost completely in the transverse direction Y.

[0079] The compression-recovery layer 8 is compressed by pressure applied by the wearer while being worn, and at that time, liquid is easily released to the outside from the compression-recovery layer 8. Pressure is not applied uniformly, so by overlapping the liquid retaining layer 5 with the compression-recovery layer 8 within the above range, released liquid is easily brought into contact with the liquid retaining layer 5, making it easier for the liquid to be absorbed on the side farthest from the skin (the liquid retaining layer), and improving the ability to suppress liquid return.

[0080] Furthermore, in the napkin 1 of this embodiment, the liquid retaining layer 5 and the compressed and resilient layer 8 have substantially the same dimension (total length) in the longitudinal direction X, and the external shapes of the liquid retaining layer 5 and the compressed and resilient layer 8 are substantially the same, with the two layers substantially overlapping. In this way, the liquid retaining layer 5 is in contact with the entire non-skin side of the compressed and resilient layer 8, so that liquid is efficiently transferred from the compressed and resilient layer 8 to the liquid retaining layer 5 over the entire surface of the compressed and resilient layer 8 and is more reliably absorbed and retained by the liquid retaining layer 5, further improving the liquid retention-inhibiting effect and the liquid return-inhibiting ability.

[0081] Furthermore, in this embodiment, the absorbent fiber layer 7, the compression-resilience layer 8, and the liquid retaining layer 5 have approximately the same width, and overlap each other in the middle region M2. With this configuration, liquid can be transferred quickly between layers throughout the entire intermediate region M2, where the wearer supplies a particularly large amount of liquid, and the liquid can be absorbed and retained by the liquid retention layer 5, further improving the effect of inhibiting the accumulation of liquid and the ability to inhibit liquid return.

[0082] In plan view, the liquid retaining layer 5 may extend beyond the compressed and resilient layer 8 located in the middle region M2 and may be located in front of and / or behind it in the longitudinal direction X. When the wearer applies force to the napkin 1 from the front region M1 and / or the rear region M3 toward the middle region M2, for example, while sleeping or sitting for long periods of time, shear stress is applied between the seat side (liquid retaining layer side) and the wearer side (compression and resilience layer side), which may cause a relative displacement in the front-to-rear direction between the liquid retaining layer 5 and the compressed and resilient layer 8. In this case, by having the liquid retaining layer 5 located in front of and / or behind the normal position of the compressed and resilient layer 8 (the position before it is displaced in the front-to-rear direction by an external force), the liquid that has permeated the compressed and resilient layer 8 can be more reliably received by the liquid retaining layer 5.

[0083] [Core Wrap Sheet] The core wrap sheet 6 is a sheet member that encases the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5. The core wrap sheet 6 encases the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5, which are layered in this order in the thickness direction Z, as a whole, and has the function of holding each layer together and maintaining the shape of each layer. The core wrap sheet 6 is formed, for example, from a thin, soft paper such as tissue paper or a liquid-permeable nonwoven fabric. In the napkin 1, the absorbent body 4 is typically sandwiched between the topsheet 2 and the backsheet 3 and compressed in the thickness direction, so that the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5 are integrated, improving the transfer of liquid between the layers.

[0084] The absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5, which are wrapped in the core wrap sheet 6, are not bonded to each other with any adhesive, and no adhesive is contained within each layer. By wrapping the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5 together with the core wrap sheet 6, the integrated laminated state of each layer is maintained without using any adhesive between or within each layer, and the shape of the absorbent body 4 can be maintained, and liquid transfer between the layers can be smoothed. Furthermore, by not using any adhesive, the use of an adhesive does not hinder liquid absorption, improving the water absorption of the absorbent body 4 and improving liquid transfer between the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5.

[0085] <Method of manufacturing absorbent body>

[0086] An example of a method for manufacturing the absorbent body 4 will now be described. The absorbent body 4 can be manufactured in a conventional manner using a known fiber-stacking device equipped with a rotating drum. The fiber-stacking device typically includes a rotating drum having a collection recess formed on its circumferential surface, and a duct having an internal flow path for transporting the absorbent fiber layer-forming material (absorbent fiber 70, superabsorbent polymer 71), the compressed and recovering layer material (fiber mass 80), and the superabsorbent polymer 51 to the collection recess. While the rotating drum is rotated around its rotation axis along the drum circumferential direction, the forming material is transported by an airflow generated in the flow path by suction from the inside of the rotating drum, and is stacked in the collection recess. The arrangement of the absorbent fiber layer 7 and the compressed and recovering layer 8 in the absorbent body 4 can be achieved by appropriately adjusting the stacking order of the respective forming materials on the rotating drum in the manufacturing method using the fiber-stacking device.

[0087] The absorbent body 4 can be manufactured by the following two methods using a known fiber stacking device. (1) A method in which two fiber stacking devices are used, and the fiber stack (absorbent fiber layer 7) produced by one fiber stacking device is stacked on top of the fiber stack (compressed recovery layer 8) produced by the other fiber stacking device, and then a superabsorbent polymer 51 and an absorbent sheet 52 are arranged in order, and covered with a core wrap sheet 6. (2) A method in which a single fiber stacking device is used, and the timing of supplying the material for forming the compressed recovery layer 8 (fiber mass 80) to the accumulation recess is different from that of the material for forming the absorbent fiber layer 7 (absorbent fiber 70, superabsorbent polymer 71), to produce the absorbent fiber layer 7 and the compressed recovery layer 8, and then the superabsorbent polymer 51 and the absorbent sheet 52 are arranged in order and covered with a core wrap sheet 6.

[0088] <Action and effect>

[0089] In the napkin 1 of this embodiment, if an excessive amount of liquid is supplied to the absorbent body 4, for example, when the napkin 1 is worn for a long period of time, any liquid that cannot be retained by the absorbent fiber layer 7 will transfer to the compressed and resilient layer 8. The liquid that has transferred to the compressed and resilient layer 8 is easily transferred to the liquid retaining layer 5 located below the compressed and resilient layer 8, which is adjacent to and integrated with the compressed and resilient layer 8 by the core wrap sheet 6. The liquid that has transferred to the liquid retaining layer 5 is absorbed and retained by the liquid retaining layer 5, thereby preventing liquid from pooling in the compressed and resilient layer 8. This prevents a decrease in cushioning properties and compression and resilience due to liquid pooling in the compressed and resilient layer 8, and allows the compressed and resilient layer 8 to maintain good compression and resilience from the beginning of wear over time, ensuring a good fit even when worn for long periods of time.

[0090] <Additional Description of This Embodiment>

[0091] [State of the interface between the compression recovery layer and the liquid retention layer] As described above, in the napkin 1, by sandwiching the absorbent body 4 between the topsheet 2 and backsheet 3 and pressing it in the thickness direction, the absorbent fiber layer 7, the compressed and recovering layer 8, and the liquid retaining layer 5 are integrated, and as shown in Figure 5, at the interface 13 between the compressed and recovering layer 8 and the liquid retaining layer 5, part of the superabsorbent polymer 51 located near said interface 13 is embedded in fiber agglomerates 80. The "interface between the compressed and recovering layer and the liquid retaining layer" refers to the boundary, parallel to the XY plane, between the region where fiber agglomerates are present in the thickness direction and the region where no fiber agglomerates are present.

[0092] By embedding the superabsorbent polymer 51 in the fiber mass 80 in this way, the fiber mass 80 and the superabsorbent polymer 51 are always in contact, improving the ability of the superabsorbent polymer 51 to draw liquid from the compression-recovery layer 8 and enabling more efficient use of the liquid absorption and retention functions of the superabsorbent polymer 51. This further suppresses the accumulation of liquid in the compression-recovery layer 8, allowing the compression-recovery property of the compression-recovery layer 8 to be maintained in a good state, and maintaining a good fit to the wearer.

[0093] [Compression groove] As shown in Figure 1, the napkin 1 has a pair of left and right central compressed grooves 20, a front lateral compressed groove 31, a first rear compressed groove 32, and a second rear compressed groove 33. The compressed grooves are formed by applying a known compression process, with or without the application of heat, from the topsheet 2 side of the main body M in the thickness direction Z. The compressed grooves are more rigid than non-compressed areas, and can suppress undesirable deformation such as crease of the napkin 1 when worn. Furthermore, the compressed grooves can induce deformation into a shape that fits the wearer when worn, and can also improve the effectiveness of preventing liquid leakage outward in the horizontal direction Y and the vertical direction X of the napkin 1.

[0094] As shown in Figure 4, the napkin 1 has a region 25 that has been compressed to provide compressed grooves, and a third region 26 that is not compressed and does not provide compressed grooves. In the compressed region 25, the topsheet 2 and part of the absorbent body 4 are compressed to be integrated in the thickness direction Z, and the density (fiber density) of the constituent materials (constituent fibers) of the topsheet 2 and the absorbent body 4 is higher than in the non-compressed region. As a result of being compressed, the skin-facing side (topsheet 2 side) of the napkin 1 in the region 25 where the compressed grooves are provided is recessed overall downward in the thickness direction Z compared to the skin-facing side of the topsheet 2 in the third region 26.

[0095] As shown in Figure 1, the pair of left and right central compressed grooves 20 extend linearly in the longitudinal direction X. The pair of left and right central compressed grooves 20 are symmetrical about the longitudinal centerline CL. The central compressed grooves 20 are provided in a continuous linear shape in the longitudinal direction X, passing through the middle region M2 where the absorbent fiber layer 7, the compressed and resilient layer 8, and the liquid retaining layer 5 overlap, and also passing through part of the front region M1 and part of the rear region M3 located before and after the middle region M2, where the compressed and resilient layer 8 and the liquid retaining layer 5 are not present.

[0096] As shown in Figures 1 and 4, a pair of left and right skin-side central compressed grooves 20a are formed on the topsheet 2 side of the main body M. Furthermore, although not shown, a pair of left and right non-skin-side central compressed grooves 20b, which are recesses that overlap the pair of left and right skin-side central compressed grooves 20a in plan view, may be formed on the non-skin side 42 side of the absorbent body 4. The absorbent body 4 has central compressed grooves 20 (skin-side central compressed grooves 20a) that overlap each other in plan view seen from the thickness direction on the skin side 41 in the region where the absorbent fiber layer 7, the compressed and recovering layer 8, and the liquid retaining layer 5 overlap. Note that when a non-skin-side central compressed groove 20b is provided, and there is no need to particularly distinguish between the skin-side central compressed groove 20a and the non-skin-side central compressed groove 20b, they will be referred to as central compressed grooves 20.

[0097] The skin-side central compressed groove 20a is formed by compressing the laminate including the topsheet 2 and the absorbent body 4 in the thickness direction Z from the topsheet 2 side. As shown in Figure 4, in the middle region M2, the skin-side central compressed groove 20a has a configuration in which the topsheet 2 and absorbent body 4 are integrally recessed toward the backsheet 3. More specifically, the skin-side central compressed groove 20a is formed by integrally compressing the topsheet 2, the upper core wrap sheet 6, the absorbent fiber layer 7, and a portion of the compressed and recoverable layer 8. When the non-skin-side central compressed groove 20b is formed, the non-skin-side central compressed groove 20b has a configuration in which the absorbent body 4 is integrally recessed toward the topsheet 2. More specifically, the non-skin-side central compressed groove 20b is formed by integrally slightly recessing the lower core wrap sheet 6 and the liquid retaining layer 5 toward the topsheet 2.

[0098] As shown in Figure 4, in the region 25 of the middle region M2 where the central compressed groove 20 is provided, the compressed and recoverable layer 8 has a compressed region 85 and a non-compressed region 86. The compressed region 85 is a partial region of the compressed and recoverable layer 8 that is compressed together with the top sheet 2, the upper core wrap sheet 6, and the absorbent fiber layer 7 by the compression process. The non-compressed region 86 is the remaining region of the compressed and recoverable layer 8 that was not compressed by the compression process.

[0099] In the napkin 1 of this embodiment, the skin-side central compressed groove 20a, which is formed by integrating the top sheet 2, the upper core wrap sheet 6, the absorbent fiber layer 7, and the compressed area 85 of the compression recovery layer 8, can suppress undesirable deformation such as crease of the napkin 1 when worn. Furthermore, in the region 25 where the central compressed groove 20 is provided in the middle region M2 of the absorbent body 4, the non-skin-side central compressed groove 20b is provided, which brings the liquid retaining layer 5 closer to the compressed and recovering layer 8 compared to the third region 26 where no compressed groove is provided, thereby further promoting liquid transfer from the compressed and recovering layer 8 to the liquid retaining layer 5. This can further suppress liquid accumulation in the compressed and recovering layer 8.

[0100] The compressed and resilient layer 8, which corresponds to the central compressed groove 20 provided in the area where the absorbent fiber layer 7, compressed and resilient layer 8 and liquid retaining layer 5 overlap, preferably has a non-compressed area 86 as shown in FIG. With this configuration, the compression and recovery effect of the compression and recovery layer 8 is more likely to be exhibited in the region where the central compressed groove 20 is provided. In other words, in plan view, the napkin 1 has an area that has not been compressed by compression processing across the entire area where the compression and recovery layer 8 is present, and the compression and recovery effect of the compression and recovery layer 8 can be exhibited well across the entire area.

[0101] Furthermore, even in compressed grooves that do not overlap the compressed and recoverable layer 8 and the liquid retaining layer 5 in plan view (part of the central compressed groove 20, front lateral compressed groove 31, first rear compressed groove 32, second rear compressed groove 33), skin-side compressed grooves are formed by the compression process on the topsheet 2 side, in which the topsheet 2 and absorbent body 4 are integrally depressed toward the backsheet 3 side. Non-skin-side compressed grooves may be formed on the non-skin-facing side of the absorbent body 4, in which the absorbent body 4 is integrally depressed toward the topsheet 2 side. In this case, the skin-side compressed groove and the non-skin-side compressed groove overlap each other in plan view.

[0102] Thus, by providing compressed grooves on the skin-side surface 41 of the absorbent body, the napkin 1 is prevented from undesirably deforming, such as creasing, during wear, and furthermore, in the middle region M2 where the compressed and recoverable layer 8 is present, liquid transfer from the compressed and recoverable layer 8 to the liquid retaining layer 5 is promoted. In particular, if the skin-side surface 41 and the non-skin-side surface 42 of the absorbent body each have compressed grooves that overlap each other in a plan view seen in the thickness direction Z, the above-mentioned effects can be more pronounced.

[0103] Of the central compressed grooves 20, only the skin-side central compressed groove 20a is arranged in the portion that overlaps with the compression recovery layer 8 and the liquid retention layer 5 in a planar view, but the non-skin-side central compressed groove 20b may be arranged in only a portion of the area that overlaps with the skin-side central compressed groove 20a in a planar view. Furthermore, in this embodiment, it is preferable that in the portion of the central compressed groove 20 that does not overlap with the compression recovery layer 8 and the liquid retention layer 5 in a planar view, the skin-side central compressed groove 20a and the non-skin-side central compressed groove 20b are arranged so as to overlap in a planar view.

[0104] <Other embodiments>

[0105] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the gist of the present invention.

[0106] For example, the absorbent article to which the present invention can be applied is not limited to sanitary napkins. Specifically, the present invention can be applied to pad-type absorbent articles similar to sanitary napkins, such as urine absorption pads and panty liners. [Explanation of symbols]

[0107] 1, 1A... Napkins, sanitary napkins (absorbent articles) 2...Surface sheet 3...Back sheet 4...Absorbent 5…Liquid retention layer 6...Core wrap sheet (sheet member) 7...Absorbent fiber layer 8...Compression and recovery layer 70...Absorbent fiber

Claims

1. An absorbent article comprising a top sheet, a back sheet, and an absorbent body disposed between the top sheet and the back sheet, The absorbent body is an absorbent fiber layer including absorbent fibers positioned on the skin side; a compression recovery layer located on the non-skin side; a liquid-retaining layer located closer to the skin than the compression-recovery layer; a sheet member that encases the absorbent fiber layer, the compression-resilience layer, and the liquid-retaining layer; having Absorbent articles.

2. The absorbent article according to claim 1, The liquid retaining layer includes a water-absorbent sheet mainly composed of absorbent fibers. Absorbent articles.

3. The absorbent article according to claim 1 or 2, The liquid retaining layer contains a highly absorbent polymer. Absorbent articles.

4. The absorbent article according to claim 3, The liquid retaining layer is an absorbent sheet mainly composed of absorbent fibers; the highly absorbent polymer disposed on the skin-side surface of the absorbent sheet; Including, Absorbent articles.

5. The absorbent article according to claim 4, The water-absorbent sheet and the superabsorbent polymer are not bonded to each other. Absorbent articles.

6. The absorbent article according to claim 3, The compression recovery layer is configured to include a plurality of entangled fiber agglomerates, a part of the superabsorbent polymer located at the interface between the liquid retaining layer and the compression recovery layer is embedded in the fiber mass; Absorbent articles.

7. The absorbent article according to claim 1 or 2, the absorbent body has, in an area where the absorbent fiber layer, the compression recovery layer, and the liquid retention layer overlap, compressed grooves that overlap each other in a plan view seen from the thickness direction on both the skin side and non-skin side; Absorbent articles.

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