Absorbent article

Abstract

An absorbent article (1) has a longitudinal direction, a width direction, and a thickness direction that are orthogonal to each other, and is provided with an absorbent core (11) and a core wrap sheet (12) provided closer to the skin side than the absorbent core (11). The absorbent article (1) is characterized in that the absorbent core (11) contains crushed fibers, the core wrap sheet (12) contains cellulose fibers, and the average fiber length of the crushed fibers is shorter than the average fiber length of the cellulose fibers.

Description

absorbent articles

[0001] The present invention relates to an absorbent article.

[0002] Absorbent articles that absorb bodily waste such as menstrual blood and urine are known. The absorbent articles include an absorbent member, and for example, Patent Document 1 discloses an absorbent member that uses fluff pulp such as pulp derived from coniferous trees or broad-leaved trees. It is known that the longer the fibers used in the absorbent member, the more easily absorbed bodily waste is dispersed along the fibers; for example, it is known that the fiber length of pulp fibers derived from coniferous trees is relatively long, and the fiber length of pulp fibers derived from broad-leaved trees is relatively short.

[0003] JP 2023-147290 A

[0004] When an absorbent article is worn, it is preferable to transfer absorbed excrement from the skin side of the absorbent article to the non-skin side so that the excrement can be quickly removed from the wearer's skin. Conventional absorbent articles have problems in that excrement absorbed by the absorbent article tends to spread in a plane rather than transferring from the skin side to the non-skin side, resulting in the excrement remaining on the skin side of the absorbent article, causing discomfort to the wearer, or causing the excrement to leak from the absorbent article.

[0005] The present invention has been made in consideration of the above-mentioned conventional problems, and its object is to make it easier to transfer excrement from the skin side to the non-skin side in the thickness direction of an absorbent article.

[0006] The main invention for achieving the above object is an absorbent article having a longitudinal direction, a width direction, and a thickness direction which are perpendicular to each other, and comprising an absorbent core and a core wrap sheet provided on the skin side of the absorbent core, wherein the absorbent core contains pulverized fibers, the core wrap sheet contains cellulose fibers, and the average fiber length of the pulverized fibers is shorter than the average fiber length of the cellulose fibers. Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0007] According to the present invention, excrement can be easily transferred from the skin side to the non-skin side in the thickness direction of the absorbent article.

[0008] 1 is a plan view of the napkin 1 as seen from the skin side. FIG. 2 is a plan view of the napkin 1 as seen from the non-skin side. FIG. 3 is a schematic cross-sectional view taken along the arrows A-A in FIG. 1. FIG. 4A is a plan view of the absorbent core 11. FIG. 4B is a schematic cross-sectional view taken along the arrows J-J in FIG. 4A. FIG. 4B is an enlarged schematic cross-sectional view taken along the arrows K-K in FIG. 4A. FIG. 3 is an enlarged view of the absorbent body 10 in FIG. 3. FIG. 4A is a plan view of the absorbent body 10 as seen from the skin side. FIG. 5 is a diagram showing the fiber length distribution of hardwood fibers and softwood fibers. FIG. 6 is an enlarged schematic diagram illustrating the absorption of bodily waste by the absorbent body 10. FIG. 7 is a diagram showing the distribution of average fiber widths of hardwood fibers and softwood fibers. FIG. 8 is a table showing the change in SAP diameter when SAP is swelled at a predetermined water absorption capacity / water retention capacity. FIG. 9 is a table showing the particle size distribution of SAP used in this embodiment. FIG. 10 is a diagram illustrating each part of the absorbent core 11 in the longitudinal and width directions.

[0009] The present specification and the accompanying drawings make at least the following clear: (Aspect 1) An absorbent article having a longitudinal direction, a width direction, and a thickness direction that are perpendicular to one another, and comprising an absorbent core and a core wrap sheet provided on the skin side of the absorbent core, wherein the absorbent core contains pulverized fibers, the core wrap sheet contains cellulose fibers, and the average fiber length of the pulverized fibers is shorter than the average fiber length of the cellulose fibers.

[0010] According to aspect 1, there are more contact points inside the absorbent core where excrement comes into contact with the pulverized fibers than when the average fiber length of the pulverized fibers is longer than the average fiber length of the cellulose fibers, making it easier for excrement to migrate from the skin side to the non-skin side in the thickness direction along the fibers in the absorbent core.

[0011] (Aspect 2) An absorbent article according to aspect 1, characterized in that it has a plurality of absorbent compressed sections formed by compressing the absorbent core and the core wrap sheet in the thickness direction, the length of the absorbent compressed sections in the width direction being greater than the average fiber width of the crushed fibers, and the absorbent compressed sections have portions where, when viewed in the thickness direction, the absorbent compressed sections overlap with a plurality of the crushed fibers.

[0012] According to aspect 2, it is possible to provide multiple areas in the absorbent core where the density of the crushed fibers is partially increased, making it easier to draw excrement from the core wrap sheet into the absorbent core and promoting absorption in the absorbent core.

[0013] (Aspect 3) An absorbent article according to Aspect 2, characterized in that it has a central compression section in which the absorbent core and the core wrap sheet are compressed in the thickness direction, and a plurality of the absorbent body compression sections, the central compression section being provided along the longitudinal direction and in the center in the width direction, and a plurality of the absorbent body compression sections being provided on both sides of the central compression section in the width direction.

[0014] According to aspect 3, the inclusion of the central compression section deforms the absorbent core so that the central section in the width direction protrudes toward the skin, promoting longitudinal diffusion, while the absorbent body compression section facilitates diffusion within the absorbent core. In addition, the central compression section and the absorbent body compression section facilitate preventing the absorbent core from losing its shape.

[0015] (Aspect 4) The absorbent article according to any one of aspects 1 to 3, wherein no adhesive is provided between the skin side of the absorbent core and the non-skin side of the core wrap sheet.

[0016] According to aspect 4, the area of ​​contact between the absorbent core and the core wrap sheet can be reduced compared to when adhesive is provided between the skin side of the absorbent core and the non-skin side of the core wrap sheet, which makes it easier to promote absorption of excrement in the thickness direction into the absorbent core from a state in which the excrement has been dispersed in the core wrap sheet, thereby making it easier to improve the rate at which excrement is absorbed.

[0017] (Aspect 5) The absorbent article of any one of Aspects 1 to 4, wherein the absorbent core comprises a superabsorbent polymer, and the cellulose fibers have an average fiber length greater than the average diameter of the superabsorbent polymer when not immersed in saline and smaller than the average diameter of the superabsorbent polymer when immersed in saline for 60 minutes and then drained for 15 minutes.

[0018] According to aspect 5, the risk that the core wrap sheet will hinder the swelling of the superabsorbent polymer is reduced, making it easier for the superabsorbent polymer to exert its absorption function within the absorbent core.

[0019] (Aspect 6) An absorbent article according to any one of aspects 1 to 5, characterized in that the core wrap sheet has an overlapping portion where the core wrap sheets overlap each other on the skin side of the absorbent core, no adhesive is provided between the core wrap sheets in the overlapping portion, the overlapping portion is provided in the center of the width direction and along the longitudinal direction, the widthwise length of the overlapping portion is longer than the average fiber length of the pulverized fibers, and the widthwise length of the overlapping portion is longer than the average fiber length of the cellulose fibers.

[0020] According to aspect 6, since the core wrap sheets are not adhered to the absorbent core and are not adhered to each other at the overlapping portions, the penetration of excrement in the thickness direction at the overlapping portions is delayed, which makes it easier to promote the planar diffusion of excrement in the core wrap sheets, particularly in the longitudinal direction, and therefore makes it easier to retain excrement subsequently absorbed by the absorbent core over a wide area within the absorbent core.

[0021] (Aspect 7) The absorbent article of any one of Aspects 1 to 6, wherein the weight ratio of the fibers along the longitudinal direction among the pulverized fibers is greater than the weight ratio of the fibers along the longitudinal direction among the cellulose fibers.

[0022] According to aspect 7, by making it easier to spread excrement in the longitudinal and width directions in the core wrap sheet, while also making it easier to spread excrement in the longitudinal direction in the absorbent core, the risk of excrement leaking outside the width direction of the absorbent article can be reduced.

[0023] (Aspect 8) The absorbent article according to any one of aspects 1 to 7, wherein the average fiber width of the comminuted fibers is larger than the average fiber width of the cellulose fibers.

[0024] According to aspect 8, the absorbent core is more likely to retain liquid than the core wrap sheet when the average fiber width of the crushed fibers is smaller than the average fiber width of the cellulose fibers, thereby reducing the risk of excrement leaking from the absorbent article.

[0025] (Aspect 9) An absorbent article according to any of aspects 1 to 8, characterized in that it has a plurality of absorbent compressed portions formed by compressing the absorbent core and the core wrap sheet in the thickness direction, and a non-compressed portion where the absorbent core and the core wrap sheet overlap when viewed in the thickness direction and where the absorbent compressed portion is not provided, and that the number of fiber agglomerates in the non-compressed portions of the absorbent core that are densely packed with the crushed fibers and have a density higher than the average density of the absorbent core is greater than the number of fiber agglomerates in the non-compressed portions of the core wrap sheet that are densely packed with the cellulose fibers and have a density higher than the average density of the core wrap sheet.

[0026] According to aspect 9, the core wrap sheet makes it easier to diffuse excrement over a wider area than to absorb it, while the absorbent core has a large number of fiber agglomerates, which allows for improved absorption and liquid retention within the absorbent core through capillary action.

[0027] (Aspect 10) The absorbent article of Aspect 9, wherein the number of fiber agglomerates in the non-compressed portion of the core wrap sheet that are densely packed with cellulose fibers and have a density higher than the average density of the core wrap sheet is zero.

[0028] According to aspect 10, the core wrap sheet makes it easier to diffuse excrement over a wider area than to absorb it, while the absorbent core has a large number of fiber agglomerates, which allows for improved absorption and liquid retention within the absorbent core through capillary action.

[0029] (Aspect 11) An absorbent article according to any one of aspects 1 to 10, characterized in that it has a plurality of absorbent body compressed portions formed by compressing the absorbent core and the core wrap sheet in the thickness direction, and a non-compressed portion where the absorbent core and the core wrap sheet overlap when viewed in the thickness direction and where the absorbent body compressed portion is not provided, the non-compressed portion of the absorbent core has fiber agglomerates that are densely packed with the crushed fibers and have a density higher than the average density of the absorbent core, the absorbent core has a skin side portion, a middle portion and a non-skin side portion when the absorbent core is divided into thirds in the thickness direction, and the number of fiber agglomerates densely packed with the crushed fibers in the middle portion is greater than the number of fiber agglomerates densely packed with the crushed fibers in the skin side portion.

[0030] According to aspect 11, excrement can be more easily drawn from the skin-side portion to the intermediate portion of the absorbent core, and excrement once absorbed in the intermediate portion can be more easily prevented from returning to the skin-side portion.

[0031] (Aspect 12) An absorbent article according to any one of aspects 1 to 11, characterized in that it has a plurality of absorbent body compressed portions formed by compressing the absorbent core and the core wrap sheet in the thickness direction, and a non-compressed portion where the absorbent core and the core wrap sheet overlap when viewed in the thickness direction and where the absorbent body compressed portion is not provided, and the non-compressed portion of the absorbent core has fiber agglomerates that are densely packed with the crushed fibers and have a density higher than the average density of the absorbent core, and when the absorbent core is divided into thirds in the longitudinal direction and the width direction, each has, from one side to the other, one side, a central portion, and the other side portion, and the number of fiber agglomerates with densely packed crushed fibers in the central portion is greater than the number of fiber agglomerates with densely packed crushed fibers in the one side portion.

[0032] According to Aspect 12, it is possible to improve the absorbency in the area close to the wearer's excretory opening.

[0033] (Aspect 13) The absorbent article of any one of Aspects 1 to 12, wherein the pulverized fibers include hardwood fibers made of hardwood, and the weight ratio of the hardwood fibers to the pulverized fibers is 85% or more.

[0034] According to Aspect 13, it is easy to create fiber agglomerates of densely packed pulverized fibers inside the absorbent core, and portions of fiber agglomerates with high fiber density and portions of fiber density lower than the fiber agglomerates are provided. This improves absorbency by capillary action in the fiber agglomerates, while making it easier to retain excrement in the gaps between fibers in the portions of fiber density lower than the fiber agglomerates, making it easier for the absorbent core to efficiently absorb excrement.

[0035] (Aspect 14) The absorbent article of any one of aspects 1 to 13, wherein the core wrap sheet contains a paper strength agent, and the absorbent core does not contain the paper strength agent.

[0036] According to aspect 14, by providing a paper strength enhancer in the core wrap sheet, the strength of the core wrap sheet is improved while the risk of the absorbent core's water retention being reduced by the paper strength enhancer is reduced, and by covering the absorbent core with a core wrap sheet having improved strength, the shape of the absorbent core is more easily maintained.

[0037] This Embodiment Hereinafter, a sanitary napkin will be described as an example of an absorbent article according to this embodiment. However, the sanitary absorbent article is not limited to a sanitary napkin, and may be a shorts-type napkin, a pants-type disposable diaper, a tape-type disposable diaper, an absorbent pad, or the like.

[0038] <<<Configuration of the napkin 1 of this embodiment>>> Fig. 1 is a plan view of the napkin 1 as seen from the skin side. Fig. 2 is a plan view of the napkin 1 as seen from the non-skin side. Fig. 3 is a schematic cross-sectional view taken along the arrows A-A in Fig. 1. The napkin 1 has a longitudinal direction, a width direction, and a thickness direction. In the longitudinal direction, the side that contacts the wearer's lower abdomen is the front side, and the side that contacts the wearer's buttocks is the rear side. In the thickness direction, the side that contacts the wearer's skin is the skin side, and the opposite side is the non-skin side. The center line C-C shown in Fig. 1 etc. indicates the center of the napkin 1 in the width direction, and the center line CL indicates the center of the napkin 1 in the longitudinal direction. The cross-sectional views in Fig. 3 etc. show the napkin 1 schematically, and the dimensions are not necessarily accurate.

[0039] The napkin 1 has an absorbent body 10, a top sheet 21, a pair of side sheets 23, and a back sheet 31. A sheet-like second sheet 22 may be provided on the skin side of the absorbent body 10 and on the non-skin side of the top sheet 21. Each of the materials adjacent to each other in the thickness direction is joined with an adhesive such as hot melt.

[0040] The napkin 1 has a pair of wing portions 1W extending outward in the width direction from the center in the longitudinal direction. The wing portions 1W are mainly formed by the side sheets 23 and the back sheet 31. However, the napkin 1 does not necessarily have to have the wing portions 1W.

[0041] The top sheet 21 is a liquid-permeable sheet located closer to the skin than the absorbent body 10. The top sheet 21 is a surface sheet located closer to the skin than the absorbent body 10 and capable of contacting the wearer's skin. Examples of the top sheet 21 include flexible sheets such as nonwoven fabrics made of synthetic fibers such as polyethylene (PE) and polypropylene (PP) (e.g., air-through nonwoven fabrics and spunbond nonwoven fabrics), synthetic resin films with through holes, and cotton nonwoven fabric sheets. The top sheet 21 of this embodiment is formed from a liquid-permeable sheet of polyethylene terephthalate (PET) and polyethylene (PE), or air-through nonwoven fabrics or spunlace nonwoven fabrics containing water-retentive fibers such as cotton or rayon.

[0042] The pair of side sheets 23 are provided on the non-skin side of the top sheet 21 and the second sheet 22 and on the skin side of the absorbent body 10, and are sheets that extend outward from both widthwise side edges of the top sheet 21, etc. Examples of the side sheets 23 include the same soft, liquid-permeable nonwoven fabric as the top sheet 21, and a hydrophobic nonwoven fabric. Furthermore, a reinforcing sheet 24 is provided on the widthwise outer side of the top sheet 21, the second sheet 22, and the absorbent body 10, between the side sheets 23 and the back sheet 31 in the thickness direction, to reinforce the strength of the side sheets 23. The reinforcing sheet 24 can be, for example, the same sheet material as the back sheet 31, such as paper or SMS.

[0043] The back sheet (non-skin side sheet) 31 is located closer to the skin than the absorbent body 10 and is the sheet provided closest to the skin side of the napkin 1. An example of the back sheet 31 is a liquid-impermeable sheet such as a polyethylene (PE) resin film. The shape of the back sheet 31 is substantially the same as the outer shape of the napkin 1.

[0044] The back sheet 31 has a plurality of main adhesive portions (adhesive portions) 32 on the non-skin side. In this embodiment, the main adhesive portions 32 are regions to which a plurality of strips of hot melt adhesive are applied along the longitudinal direction. When the napkin 1 is worn, the main adhesive portions 32 are attached to the inside of the crotch area of ​​the underwear (garment), thereby preventing the napkin 1 from shifting position relative to the wearer's body.

[0045] The wing portion 1W has a wing adhesive portion 33 on the non-skin-facing side of the back sheet 31. In this embodiment, the wing adhesive portion 33 is a rectangular area to which hot melt adhesive is applied. When wearing the napkin 1, the wing portion 1W is folded back to the non-skin-facing side of the underwear, and the wing adhesive portion 33 is attached to the non-skin-facing side of the underwear in the crotch area, thereby securing the napkin 1 to the underwear.

[0046] The position where the adhesive wing portions 33 overlap in the longitudinal direction (see FIG. 1 ) is the crotch region CA. The crotch region CA is the region that comes into contact with the wearer's crotch in the longitudinal direction when the garment is worn, and is the region that comes into contact with the blood drainage port through which the wearer's body waste is discharged.

[0047] The absorbent body 10 includes an absorbent core 11 and a core wrap sheet 12. The absorbent core 11 is formed by molding liquid-absorbent fibers into a predetermined shape and contains crushed fibers as the liquid-absorbent fibers. The crushed fibers include hardwood fibers made from hardwood. The absorbent core 11 of this embodiment contains crushed fibers (pulp fibers), and is formed solely from hardwood fibers (100% hardwood fibers). Note that the absorbent core 11 is not limited to crushed hardwood fibers; the crushed fibers may include pulp fibers such as softwood fibers made from softwood trees in addition to hardwood fibers. The absorbent core 11 may also include liquid-absorbent fibers such as cellulosic absorbent fibers, synthetic fibers made from polyolefins, polyesters, acrylics, acrylates, etc., or superabsorbent polymers (SAPs). FIG. 4A is a plan view of the absorbent core 11. FIG. 4B is a schematic cross-sectional view taken along the arrows J-J in FIG. 4A. Fig. 5 is an enlarged schematic view of a cross section taken along the line K-K in Fig. 4A. Fig. 6 is an enlarged view of the absorbent body 10 in Fig. 3. Note that in Figs. 4A, 4B and 5, irregularities caused by compressed portions such as compressed portion EL are omitted.

[0048] The absorbent core 11 has a central portion 11d, which has a higher basis weight of liquid-absorbent fibers than the surrounding area. The central portion 11d is a portion of the absorbent core 11 where the thickness (length in the thickness direction) is greater than the surrounding area. In this embodiment, the central portion 11d is a portion that protrudes toward the skin in the thickness direction and is a generally elliptical region in a planar view. By locating the central portion 11d in the center of the absorbent core 11 in the width direction and in a position that overlaps with the crotch region CA in a planar view, the central portion 11d is more likely to contact the wearer's excretory opening when worn, making it easier for the napkin 1 to fit the wearer's body and quickly absorb excrement. Furthermore, by locating the central portion 11d, which has a higher basis weight of liquid-absorbent fibers, in a position that overlaps with the crotch region CA in a planar view, excrement discharged from the wearer's excretory opening is more likely to be retained within the absorbent core 11 when worn.

[0049] The core wrap sheet 12 is a liquid-permeable sheet member. In this embodiment, the core wrap sheet 12 is a tissue containing cellulose fibers. By covering the absorbent core 11, the core wrap sheet 12 maintains the shape of the absorbent core 11 and promotes the diffusion of liquid into the absorbent core 11.

[0050] As shown in FIG. 6 , the core wrap sheet 12 has a skin-side portion 12a located closer to the skin than the absorbent core 11 and a non-skin-side portion 12b located closer to the skin than the absorbent core 11. In this embodiment, as shown in FIG. 6 and other figures, both side edges of the core wrap sheet 12 are folded back toward the skin side of the absorbent core 11, thereby covering the skin side and non-skin side of the absorbent core 11 with the core wrap sheet 12. Specifically, the core wrap sheet 12 wraps the absorbent core 11 so as to cover the widthwise side edges of the absorbent core 11, with the leading end 12ea of ​​the core wrap sheet 12 on the outside and the leading end 12eb on the other side on the inside. However, the shape and configuration of the core wrap sheet 12 are not limited thereto. For example, the core wrap sheet 12 may be configured as two sheet members, one on the skin side and one on the non-skin side of the absorbent core 11. Note that no adhesive is provided on the inside of the core wrap sheet 12 in this embodiment. In other words, the absorbent core 11 and the core wrap sheet 12 are not fixed together with an adhesive, and the absorbent core 11 is maintained in shape by being wrapped in the core wrap sheet 12 .

[0051] Figure 7 is a plan view of the absorbent body 10 as seen from the skin side. In Figure 7, the central high portion 11d of the absorbent core 11 is omitted. As shown in Figure 7, the absorbent body 10 has a central compressed portion 14 and multiple absorbent body compressed portions 15. The central compressed portion 14 and the absorbent body compressed portions 15 are portions where the absorbent core 11 and the core wrap sheet 12 are compressed in the thickness direction, respectively.

[0052] The central compression section 14 and the absorbent body compression section 15 are formed, for example, by passing the absorbent body 10 in the manufacturing process through a roll nip between a convex roller having multiple convex sections and an anvil roller with a flat surface to compress it. In this embodiment, the central compression section 14 and the absorbent body compression section 15 are portions of the absorbent body 10 that are pressed from the non-skin side to the skin side by passing the absorbent body 10 through the roll nip with the convex roller in contact with the non-skin side of the absorbent body 10 and the anvil roller in contact with the skin side, respectively.

[0053] The central compressed section 14 is a linear compressed section provided along the longitudinal direction and at the center in the width direction. The central compressed section 14 is a section that is recessed in the thickness direction from the skin side or non-skin side from the front end to the rear end of the absorbent body 10. The central compressed section 14 is a guide section that guides the absorbent body 10 to bend toward the skin side in the thickness direction, starting from the central compressed section 14. Furthermore, because the central compressed section 14 has a higher fiber density than the uncompressed section, it also serves as a guide section that guides excrement in the longitudinal direction by capillary action.

[0054] The absorbent body compressed sections 15 are compressed sections arranged in a generally staggered pattern across the entire absorbent body 10. In this embodiment, the absorbent body compressed sections 15 are provided with a plurality of oval-shaped compressed sections. Like the central compressed section 14, the absorbent body compressed sections 15 are also sections that are recessed in the thickness direction from the skin side or non-skin side. Providing the absorbent body compressed sections 15 makes it easier to maintain the shape of the absorbent body 10. Furthermore, since the absorbent body compressed sections 15 have a higher fiber density than the uncompressed sections, they are sections of the absorbent core 11 that are more likely to absorb excrement due to capillary action. The difference in density between the absorbent body compressed sections 15 and the uncompressed sections makes it easier to suppress the diffusion of oil agent Y in the absorbent core 11, which will be described later.

[0055] As shown in Figure 1 and other figures, the napkin 1 has linear compressed portions EL and circular compressed portions ee. The linear compressed portions EL are formed by compressing at least a portion of the top sheet 21, second sheet 22, and absorbent body 10 in the thickness direction. The linear compressed portions EL of the napkin 1 of this embodiment include a front compressed portion ELa located forward of the longitudinal centerline CL, a rear compressed portion ELb located rearward of the centerline CL, and a central compressed portion ELc located between the front compressed portion ELa and the rear compressed portion ELb. The inclusion of the linear compressed portions EL strengthens the bonding of the various components in the thickness direction, increases fiber density, and improves liquid absorption. The linear compressed portions EL are linear compressed portions that extend along the longitudinal direction in a plan view, and are provided in pairs at a predetermined interval in the width direction. The absorbent body 10 has a plurality of circular compressed portions ee at a central portion in the width direction and at a position overlapping with the crotch region CA in the longitudinal direction. The circular compressed portions ee are compressed portions that are circular in plan view and are formed by compressing at least a portion of the top sheet 21, the second sheet 22, and the absorbent body 10 in the thickness direction.

[0056] Because the linear compressed portions EL and circular compressed portions ee are formed by compressing members stacked in the thickness direction, the fiber density of each member in each compressed portion is higher than the fiber density of portions where no compressed portions are provided. The linear compressed portions EL and circular compressed portions ee are formed, for example, by passing the napkin 1 in the manufacturing process through a roll nip between a convex roller having multiple convex portions and an anvil roller with a flat surface, thereby squeezing the napkin.

[0057] <<<Regarding the absorbent body 10>>> The absorbent body 10 of the napkin 1 comprises an absorbent core 11 and a skin-side portion 12a of a core wrap sheet 12 provided on the skin side of the absorbent core 11. The absorbent core 11 contains pulverized fibers 11f, and the skin-side portion 12a (core wrap sheet 12) contains cellulose fibers 12f. The average fiber length of the pulverized fibers 11f of the absorbent core 11 is shorter than the average fiber length of the cellulose fibers 12f of the skin-side portion 12a.

[0058] The absorbent core 11 includes pulp, such as wood pulp obtained from softwood (e.g., southern yellow pine) or hardwood (e.g., eucalyptus), non-wood pulp such as bagasse, kenaf, bamboo, hemp, and cotton (e.g., cotton linter); regenerated cellulose fibers such as rayon; and semi-synthetic fibers such as acetate fibers. Softwood fibers (softwood pulp), which have relatively long fiber lengths, are often used in absorbent articles. In contrast, the pulverized fibers 11f of the absorbent core 11 of this embodiment are composed solely of hardwood fibers (hardwood pulp) (100% hardwood fibers).

[0059] 8 shows the distribution of fiber lengths of hardwood fibers and softwood fibers. The average fiber length of softwood fibers (softwood pulp) is 2.5 mm, while the average fiber length of hardwood fibers (hardwood pulp) is 0.79 mm. In other words, the average fiber length of hardwood fibers is shorter than the average fiber length of softwood fibers.

[0060] The skin side portion 12a (core wrap sheet 12) contains cellulose fibers 12f. The cellulose fibers 12f are fibers made from wood or recycled paper, and are primarily composed of cellulose. The core wrap sheet 12 of this embodiment is a tissue. Examples of fibers constituting tissue include recycled paper pulp from wood pulp waste paper derived from coniferous or broad-leaved trees, non-wood pulp made from plants such as kenaf or bamboo, and synthetic fiber pulp. The tissue of the skin side portion 12a of this embodiment is composed of 60% to 70% by weight of softwood fibers derived from softwood trees and 30% to 40% by weight of hardwood fibers derived from broad-leaved trees, with a higher content of softwood fibers having a longer average fiber length. The average fiber length of the cellulose fibers in the skin side portion 12a is 1.8 mm.

[0061] Fig. 9 is an enlarged schematic diagram illustrating the absorption of excrement by the absorbent body 10. Fig. 9 is a schematic diagram showing an enlarged view of the skin-side portion 12a and a portion of the absorbent core 11, and for convenience, the overlapping portion of the core wrap sheets 12 (skin-side portion 12a) on the skin side of the absorbent core 11 and the central peak 11d of the absorbent core 11 are omitted.

[0062] The longer the fibers, the easier it is for excrement (liquid) to diffuse along them. Furthermore, the shorter the fibers, the shorter the inter-fiber distance. When the average fiber length of the pulverized fibers 11f in the absorbent core 11 is shorter than the average fiber length of the cellulose fibers 12f in the skin-side portion 12a, the excrement is more easily dispersed horizontally in the skin-side portion 12a than when the average fiber length of the pulverized fibers 11f is longer than the average fiber length of the cellulose fibers 12f. When the excrement dispersed in the skin-side portion 12a reaches the absorbent core 11, the number of contact points between the excrement and the pulverized fibers 12f increases inside the absorbent core 11, facilitating the transfer of the excrement from the skin side to the non-skin side in the thickness direction so that the excrement falls along the pulverized fibers 11f and between the pulverized fibers 11f to the non-skin side. Specifically, when worn, when excrement such as menstrual blood is discharged into the crotch area CA, it is first easily diffused outward from the crotch area CA by the skin-side portion 12a which is equipped with cellulose fibers 12f having a long average fiber length, and when the diffused excrement moves from the skin-side portion 12a to the absorbent core 11, it moves so as to fall from the skin side to the non-skin side between the crushed fibers 11f having a short average fiber length, thereby reducing the risk of excrement remaining on the skin side of the crotch area CA and causing adverse effects on the wearer's skin or discomfort.

[0063] The fibers of the skin-side portion 12a (core wrap sheet) can be extracted, for example, by the following method. First, the napkin 1 is decomposed using toluene to extract the core wrap sheet 12. The extracted core wrap sheet is dried. Next, 15 g of the core wrap sheet and approximately 1.5 L of water (adjusted to a concentration of 1% relative to the weight of the core wrap sheet) are placed in a plastic container (inner diameter: 120 mm, height: 220 mm) and stirred at room temperature for approximately 24 hours using a stirrer (EYELA MAZELA Z, manufactured by Tokyo Rikakikai Co., Ltd.). Stirring is performed slowly so as not to break the fibers. The fibers dispersed in the water are then sucked up together with the water using a dropper (hole diameter: 2-3 mm). The extracted fibers are collected by suction filtration and dried. The fiber lengths of the extracted fibers are measured using an electron microscope, and the average fiber length is calculated from the measured fiber lengths.

[0064] The average fiber length of the pulverized fibers in the absorbent core 11 and the average fiber length of the fibers in the skin side portion 12a can be measured by a known method, for example, by taking an image using the above-mentioned fiber length distribution measuring device ("Valmet FS5" manufactured by Valmet Co., Ltd.) and measuring the fiber length.

[0065] The pulverized fibers 11f of the absorbent core 11 may be any pulverized fibers (such as softwood fibers or hardwood fibers) as long as they have an average fiber length shorter than that of the cellulose fibers 12f of the skin-side portion 12a. Considering that the pulverized fibers 11f have an average fiber length shorter than that of the cellulose fibers 12f, it is preferable that the pulverized fibers 11f comprise hardwood fibers.

[0066] As shown in Figure 7, the napkin 1 (absorbent body 10) preferably has multiple compressed absorbent body sections 15 formed by compressing the absorbent core 11 and the skin-side section 12a (core wrap sheet 12) in the thickness direction. Preferably, the widthwise length W15 of each compressed absorbent body section 15 is greater than the average fiber width of the pulverized fibers 11f, and the compressed absorbent body section 15 preferably has overlapping portions in the thickness direction between the compressed absorbent body sections 15 and the multiple pulverized fibers 11f. If multiple compressed absorbent body sections 15 have different widthwise lengths, it is sufficient that the length W15 of the longest widthwise section is greater than the average fiber width of the pulverized fibers 11f. In this embodiment, the widthwise length W15 of each compressed absorbent body section 15 is 0.5 to 1.0 mm, and since the pulverized fibers 11f are hardwood fibers, the average fiber width of the hardwood fibers is approximately 15 µm. Figure 10 shows the distribution of the average fiber widths of hardwood fibers and softwood fibers.

[0067] The compressed absorbent portion 15 is a portion where the fiber density is increased by compression. Therefore, by providing a portion where the compressed absorbent portion 15 and the plurality of pulverized fibers 11f overlap, it is possible to provide a plurality of portions where the fiber density of the pulverized fibers 11f in the absorbent core 11 is partially increased. This makes it easier for capillary action to draw excrement from the skin side portion 12a toward the absorbent core 11, and facilitates the absorption of excrement in the absorbent core 11.

[0068] The average fiber width of the pulverized fibers 11f can be measured by a known method. For example, it can be measured by the following method. A rectangular cutout of a portion (absorbent core 11) corresponding to the sample to be measured is used as a sample, and a 3D image stitching function of a microscope (KEYENCE VHX-2000, lens VH-Z20W, aperture fully open) is used to obtain enlarged images (e.g., 500x magnification for hardwood fibers and 100x magnification for softwood fibers) in focus from the surface of the sample to a depth of 100 μm. The widths of multiple fibers in these images are measured to calculate the average fiber width.

[0069] Furthermore, it is preferable that the napkin 1 (absorbent body 10) has a central compressed section 14 in addition to multiple absorbent body compressed sections 15. The central compressed section 14 is provided along the longitudinal direction and in the central portion in the width direction. It is preferable that multiple absorbent body compressed sections 15 are provided on both sides of the central compressed section 14 in the width direction of these compressed sections. With such an absorbent body 10, the central compressed section 14 deforms the absorbent core 11 so that the central portion in the width direction of the absorbent body 10 protrudes toward the skin, making it easier to promote the diffusion of excrement in the longitudinal direction. Furthermore, the absorbent body compressed section 15 makes it easier to promote diffusion within the absorbent core 11 (absorbent body 10). Furthermore, because the central compressed section 14 and the absorbent body compressed section 15 are portions that compress the skin-side portion 12a and the absorbent core 11 in the thickness direction, respectively, the provision of these compressed sections 14, 15 makes it easier to prevent the absorbent core 11 from losing its shape.

[0070] With respect to the skin-side portion (core wrap sheet) 12a of the core wrap sheet 12 located closer to the skin than the absorbent core 11 (FIG. 6), it is preferable that no adhesive be provided between the skin-side surface of the absorbent core 11 and the non-skin-side surface of the skin-side portion 12a. In other words, it is preferable that the skin-side surface of the absorbent core 11 and the skin-side portion 12a are not bonded together with an adhesive. This reduces the area of ​​contact between the absorbent core 11 and the skin-side portion 12a compared to when adhesive is provided between the skin-side surface of the absorbent core 11 and the non-skin-side surface of the skin-side portion 12a. As a result, as shown in FIG. 9, it is easier to promote the transfer of excrement from the skin-side portion 12a in the thickness direction (non-skin side) to the absorbent core 11 and its absorption within the absorbent core 11, rather than promoting further horizontal diffusion after the excrement has been dispersed horizontally in the skin-side portion 12a. Therefore, when worn, the excrement absorbed on the skin side of the napkin 1 is encouraged to diffuse in the skin side portion 12a and be absorbed in the thickness direction of the absorbent core 11, thereby improving the excrement absorption rate of the napkin 1 and reducing the risk of excrement remaining on the skin side of the napkin 1 and causing adverse effects on the wearer's skin or discomfort.

[0071] As shown in Figure 6 and other figures, the core wrap sheet 12 (skin side portion 12a) preferably has an overlapping portion 12r where the core wrap sheets 12 overlap each other on the skin side of the absorbent core 11. In this embodiment, in the skin side portion 12a, as shown in Figures 6 and 7, the core wrap sheet 12 covers the non-skin side of the absorbent core 11, and both side ends of the core wrap sheet 12 are folded back to the skin side of the absorbent core 11, with a tip 12ea along the longitudinal direction folded back from the other side in the width direction toward the skin side being the outer side (skin side), and a tip 12eb along the longitudinal direction folded back from one side in the width direction toward the skin side being the inner side (non-skin side), and the tip 12ea is positioned to one side in the width direction relative to the tip 12eb, thereby providing an overlapping portion 12r in the skin side portion 12a.

[0072] When the napkin 1 has an overlapping portion 12r where the core wrap sheets 12 overlap each other, it is preferable that no adhesive be provided between the skin side of the absorbent core 11 and the non-skin side of the skin side portion 12a. As shown in Figure 7, the overlapping portion 12r is preferably provided in the widthwise center and along the longitudinal direction. Furthermore, it is preferable that the widthwise length W12r of the overlapping portion 12r (5 mm in this embodiment) is longer than the average fiber length of the pulverized fibers (0.79 mm in this embodiment) and that the widthwise length W12r of the overlapping portion W12r is longer than the average fiber length of the cellulose fibers (1.8 mm in this embodiment). Since the skin side portion 12a is not adhered to the absorbent core 11 and the core wrap sheets 12 are not adhered to each other at the overlapping portion 12r, it is easier to provide areas where the core wrap sheets 12 and the skin side portion 12a are not in close contact with each other and where the absorbent core 11 are not in close contact with each other. Furthermore, because the widthwise length W12r of the overlapping portion 12r is longer than the average fiber length of the pulverized fibers and is also longer than the average fiber length of the cellulose fibers, it is easy to delay the penetration of excrement from the skin side portion 12a into the absorbent core 11 and the penetration of excrement in the thickness direction at the overlapping portion 12r. Therefore, when excrement is absorbed while wearing the absorbent core 11, planar diffusion in the core wrap sheet 12, particularly diffusion in the longitudinal direction of the excrement, is easily promoted. Therefore, the excrement that has once diffused in the skin side portion 12a is then transferred to and absorbed by the absorbent core 11, making it easy to absorb and retain the excrement over a wide range within the absorbent core 11.

[0073] When no adhesive is provided between the skin-side surface of the absorbent core 11 and the non-skin-side surface of the skin-side portion 12a and the absorbent core 11 contains a superabsorbent polymer (hereinafter also referred to as "SAP"), the average fiber length of the cellulose fibers 12f in the skin-side portion 12a is greater than the average particle size of the superabsorbent polymer before immersion in physiological saline. Furthermore, the average fiber length of the cellulose fibers 12f in the skin-side portion 12a is preferably smaller than the average particle size of the superabsorbent polymer after immersion in physiological saline for 60 minutes and subsequent draining for 15 minutes.

[0074] When not immersed in saline, i.e., before absorbing excrement, the average fiber length of the cellulose fibers 12f in the skin-side portion 12a is greater than the average particle diameter of the superabsorbent polymer, and after immersion in saline, i.e., after absorbing excrement, the average fiber length of the cellulose fibers 12f in the skin-side portion 12a is smaller than the average particle diameter of the superabsorbent polymer, which reduces the risk that the skin-side portion 12a will interfere with the swelling of the superabsorbent polymer and makes it easier for the superabsorbent polymer to exhibit its moisture absorption and moisture retention functions.

[0075] FIG. 11 is a table showing the change in SAP diameter when SAP is swollen at a predetermined water absorption capacity and water retention capacity. In FIG. 11, the SAP particle size shown on the left side represents the particle size of the SAP before swelling, and the SAP diameter shown on the right side represents the average particle size (average diameter) of the SAP after swelling according to the water absorption capacity (water retention capacity). Specifically, the table shows the average diameter of each SAP when SAPs with particle sizes (diameters) of 150 to 850 μm before swelling are absorbed (dehydrated) with water (physiological saline solution) at water absorption capacities (water retention capacities) of 10 to 120 times. Here, "water absorption capacity" refers to the saturated amount of water that a water-absorbing medium such as SAP can absorb and retain, divided by the weight of the water-absorbing medium before absorbing water. Furthermore, "water retention capacity" refers to the amount of water that a water-absorbing medium such as SAP can retain after evaporating (dehydrating) the absorbed water, divided by the weight of the water-absorbing medium before absorbing water.

[0076] The water absorption capacity (water retention capacity) of SAP was measured according to the following procedure, with reference to "JIS K 7223-1996 Test Method for Water Absorption of Superabsorbent Polymers." First, the SAP to be measured was prepared under conditions (e.g., in a laboratory maintained under these conditions) of 20°C temperature, 60% relative humidity, and 1 atm (101.325 kPa) pressure (standard atmospheric pressure). The SAP was stored in a designated container and shaken upside down at least 10 times to uniformly mix the SAP particles. Exactly 1.00 g of the mixed SAP was measured using a medicine spoon or similar tool and placed in a separately prepared nylon net bag. The nylon net bag can be made by stacking two 200 mm x 200 mm square nylon nets, heat-sealing three sides of the square at positions 5 mm from the edge of the nylon nets, and molding the bag into a shape with only one side open. As the nylon net, for example, a 250 mesh nylon net (N-No. 250HD) manufactured by NBC Industries can be used.

[0077] After placing the SAP in the nylon net bag, the opening of the nylon net bag is heat-sealed to seal the SAP so that it does not spill out of the nylon net bag. Then, 1000 ml of saline is poured into a beaker, and the nylon bag (SAP) is immersed in the saline so that one edge of the nylon bag containing the SAP touches the bottom of the beaker. One edge of the top of the nylon bag is then fixed to the edge of the beaker with a clothespin or similar to minimize adhesion between the SAP and the nylon mesh. The bag is left in this state for 60 minutes.

[0078] The saline solution used was prepared by placing a 3-liter beaker on an electronic balance and resetting it to zero, then adding ion-exchanged water to 27.0 g of sodium chloride (reagent grade 1) to make a total of 3000.0 g, and stirring with a stirring rod until the sodium chloride was visually dissolved.

[0079] After leaving it for 60 minutes, the nylon bag containing the SAP was removed from the beaker, and the upper center of the nylon bag (e.g., 5 mm from the top end of the nylon bag and 50 mm from both ends) was clamped with clothespins and left hanging in the air for 15 minutes to drain the water. After 15 minutes, the weight of the nylon bag containing the SAP was measured. This experiment was repeated multiple times (e.g., 5 times), and the average of the measured weights was taken as the water absorption weight B.

[0080] Next, the drained nylon bag (SAP) is dehydrated using a centrifuge (HI30) manufactured by Kokusan Co., Ltd. For example, dehydration is performed for 90 seconds at a rotation speed of 850 rpm (150 G). The weight of the nylon bag (SAP) after dehydration is then measured. This experiment is repeated multiple times (for example, five times), and the average of the measured weights is taken as the water-retaining weight C.

[0081] The water absorption capacity of the SAP is calculated by subtracting the weight K of the nylon net determined in the blank test from the water absorption weight B, and the water absorption capacity of the SAP is calculated by dividing this water absorption capacity by the sample weight (1.00 g). Similarly, the water retention capacity of the SAP is calculated by subtracting the weight K' of the nylon net determined in the blank test from the water retention weight C, and the water retention capacity of the SAP is calculated by dividing this water retention capacity by the original sample weight (1.00 g).

[0082] Furthermore, the diameter (particle diameter) of the SAP before swelling and the diameter (particle diameter) after swelling were measured using a microscope. Then, based on the relationship between the measurement results of the water absorption capacity (water retention capacity) of the SAP and the measured diameter (particle diameter), a table ( FIG. 11 ) was created showing the relationship between the water absorption capacity of the SAP and the diameter (particle diameter) before and after swelling.

[0083] As shown in FIG. 11 , when the water absorption capacity (water retention capacity) of the SAP is in the range of 10 to 120 times, the average diameter (average particle size) of the SAP after swelling (after water absorption or dehydration) is larger than the diameter (150 to 850 μm) of the SAP before swelling. For example, in FIG. 11 , when the absorption capacity (water retention capacity) is 40 times, the diameter of the SAP before swelling is 500 μm (0.5 mm), while the diameter of the SAP after swelling (after water absorption) is 2.12 mm. Note that in FIG. 11 , when the water absorption capacity and water retention capacity are the same, the average diameter of the SAP after swelling also has the same value. This is because the diameter of the SAP after swelling is determined by the amount of water (physiological saline in this embodiment) retained in the SAP. In other words, if the amount of water retained in the SAP after dehydration is equal to the amount of water retained in the SAP after water absorption, the average diameter of the SAP will also be equal.

[0084] As described above, the average fiber length of the cellulose fibers in the skin side portion 12 a is 1.8 mm. As shown in Figure 11, the particle size (particle size) of the swollen superabsorbent polymer may be larger than the average fiber length (1.8 mm) of the cellulose fibers in the skin side portion 12 a.

[0085] FIG. 12 is a table showing the particle size distribution of the SAP used in this embodiment. As shown in FIG. 12, 79% (average) of the SAP used in this embodiment had particle sizes in the range of 250 to 600 μm before swelling, 12% (average) had particle sizes in the range of 600 to 850 μm, and 0% (average) had particle sizes of 850 μm or greater. Furthermore, 10% (average) had particle sizes in the range of 0 to 250 μm. Therefore, according to the data in FIG. 11, it can be seen that for approximately 32% of the SAP contained in the absorbent body 10 of this embodiment, the average particle size (particle size) of the superabsorbent polymer after swelling is greater than the average fiber length (1.8 mm) of cellulose fibers.

[0086] The average particle size of the swollen superabsorbent polymer is thus greater than the average fiber length of the cellulose fibers in the skin-side portion 12 a, thereby improving the water absorption performance of the SAP. That is, the average fiber length of the cellulose fibers in the skin-side portion 12 a is smaller than the average diameter of SAP (superabsorbent polymer) after immersion in saline for 60 minutes and then draining for 15 minutes, thereby improving the water absorption of the absorbent body 10.

[0087] Furthermore, it is preferable that the average fiber width of the pulverized fibers 11f in the absorbent core 11 be larger than the average fiber width of the cellulose fibers 12f in the skin-side portion 12a. In this embodiment, the average fiber width of the pulverized fibers 11f in the absorbent core 11 is approximately 15 μm, and the average fiber width of the cellulose fibers 12f in the skin-side portion 12a is 24 μm. The larger the average fiber width, the higher the excrement (liquid) retention. Therefore, when the average fiber width of the pulverized fibers 11f in the absorbent core 11 is larger than the average fiber width of the cellulose fibers 12f in the skin-side portion 12a, the liquid retention in the absorbent core 11 is more likely to be higher than the liquid retention in the skin-side portion 12a, compared to when the average fiber width of the pulverized fibers 11f is smaller than the average fiber width of the cellulose fibers 12f. As a result, the absorbent core 11 can easily absorb the excrement absorbed from the skin side portion 12a, reducing the risk of the excrement remaining in the skin side portion 12a, and the absorbent core 11 can easily retain the excrement, thereby reducing the risk of the excrement leaking from the napkin 1.

[0088] Furthermore, it is preferable that the weight ratio of fibers aligned in the longitudinal direction among the pulverized fibers 11f in the absorbent core 11 is greater than the weight ratio of fibers aligned in the longitudinal direction among the cellulose fibers 12f in the skin-side portion 12a. In other words, the weight ratio of fibers aligned in the width direction among the pulverized fibers 12f is greater than that of the pulverized fibers 11f. In this embodiment, the cellulose fibers 12f in the skin-side portion 12a are randomly arranged in both the longitudinal and width directions, and the weight ratio of fibers aligned in the longitudinal direction among the pulverized fibers 11f in the absorbent core 11 is greater than that of fibers aligned in the width direction. Body waste is easily dispersed along the fibers. Therefore, the cellulose fibers 12f in the skin-side portion 12a facilitate dispersion of body waste in the longitudinal and width directions, while the pulverized fibers 11f in the absorbent core 11 facilitate dispersion of body waste in the longitudinal direction. As a result, the risk of body waste leakage outward in the width direction of the napkin 1 as a whole can be reduced.

[0089] Preferably, the skin-side portion 12a (core wrap sheet 12) contains a strength enhancer, while the absorbent core 11 does not. A strength enhancer is a chemical that bonds pulp fibers together to make the paper soft and resilient, while strengthening it and making it more resistant to liquids and improving its feel against the skin. Examples of strength enhancers include polyamidoamine epichlorohydrin (PAE). By incorporating this strength enhancer in the skin-side portion 12a (core wrap sheet 12), the strength of the skin-side portion 12a can be improved. On the other hand, by not incorporating a strength enhancer in the absorbent core 11, the risk of a decrease in the water retention capacity of the absorbent core 11 can be reduced. In other words, by covering the absorbent core 11, which has reduced water retention due to the absence of a strength enhancer, with the skin-side portion 12a, which has improved strength due to the presence of a strength enhancer, the shape of the absorbent core 11 can be more easily maintained.

[0090] In the absorbent core 11, the pulverized fibers 11f preferably contain hardwood fibers made from hardwood. The weight ratio of hardwood fibers to the pulverized fibers in the absorbent core 11 is preferably 85% or more. Conventional absorbent articles such as napkins 1 generally contain coniferous fibers with a relatively long average fiber length as the pulverized fibers. In contrast, the pulverized fibers 11f in the absorbent core 11 of the napkin 1 of this embodiment are hardwood fibers, and the pulverized fibers 11f of the absorbent core 11 are composed of 100% hardwood fibers. The greater the weight ratio of hardwood fibers with a relatively short average fiber length in the pulverized fibers 11f in the absorbent core 11, the more likely it is that fiber agglomerates fk, in which the pulverized fibers are densely packed, will be formed within the absorbent core 11. The absorbent core 11 containing the fiber agglomerates fk has portions with a high fiber density and portions with a lower fiber density than the fiber agglomerates fk. In this way, by providing areas with different fiber densities, the absorbency due to capillary action in the fiber mass fk area is improved, and excrement is more easily retained in the gaps between fibers in areas with a lower fiber density than the fiber mass fk, making it easier to absorb excrement efficiently within the absorbent core 11.

[0091] As described above, the napkin 1 has a compressed absorber section 15 formed by compressing the absorbent core 11 and the skin-side section 12a (core wrap sheet 12) in the thickness direction. When the overlapping portion of the absorbent core 11 and the skin-side section 12a in the thickness direction and the portion where the compressed absorber section 15 is not provided are defined as non-compressed portions, it is preferable that the number of fiber agglomerates fk in the non-compressed portion of the absorbent core 11 is greater than the number of fiber agglomerates in the non-compressed portion of the skin-side section 12a (core wrap sheet). Furthermore, it is preferable that the number of fiber agglomerates in the non-compressed portion of the skin-side section 12a (core wrap sheet 12) is 0 (zero). The fiber agglomerates fk of the absorbent core 11 are portions of the absorbent core 11 that are denser than the average density of the absorbent core 11 and are densely packed with crushed fibers. The fiber agglomerates of the skin side portion 12a (core wrap sheet 12) are portions of the skin side portion 12a that have a higher density than the average density of the skin side portion 12a and are densely packed with cellulose fibers 12f.

[0092] Since the number of fiber agglomerates fk in the absorbent core 11 is greater than the number of fiber agglomerates in the skin-side portion 12a, the skin-side portion 12a is more likely to diffuse excrement over a wide horizontal range than to absorb it or penetrate it to the non-skin side in the thickness direction. Also, in an absorbent core 11 with a large number of fiber agglomerates fk, capillary action in the fiber agglomerates fk can be used to improve the absorption of excrement and the retention of liquid (excrement) within the absorbent core 11.

[0093] Regarding the non-compressed portions, if the absorbent body 10 and napkin 1 have compressed portions such as a central compressed portion 14, linear compressed portions EL, and point compressed portions ee in addition to the absorbent body compressed portion 15, the non-compressed portions are defined as portions that do not have any of these compressed portions.

[0094] The fiber agglomerates fk are portions in which pulp fibers are not crushed and remain in ball-like shapes during the manufacturing process. The fiber agglomerates fk are high-density portions in which pulp fibers are densely packed in the form of balls. When the fiber agglomerates fk are provided, the fiber agglomerates fk are high-density portions, and the areas surrounding the fiber agglomerates fk are low-density portions with lower fiber density than the fiber agglomerates fk. This creates a difference in fiber density, facilitating absorption through capillary action. Furthermore, the presence of the fiber agglomerates fk results in the absorbent core 11 and the core wrap sheet 12 having high-density and low-density portions in the thickness direction. This makes it easier to maintain the thickness (bulk) of the component and to enhance softness and cushioning properties compared to when high-density portions are continuous in the thickness direction, such as in the compressed portions 14 and 15.

[0095] Furthermore, when the absorbent core 11 has fiber agglomerates fk in the non-compressed portions, as shown in Fig. 5, when the absorbent core 11 is divided into three equal parts in the thickness direction, the non-compressed portions of the absorbent core 11 have, from the skin side to the non-skin side, an upper portion (skin side portion) 11a, a middle portion 11b, and a lower portion (non-skin side portion) 11c. In such a case, it is preferable that the number of fiber agglomerates fk in the middle portion 11b is greater than the number of fiber agglomerates fk in the upper portion 11a. Because the fiber agglomerates fk in the absorbent core 11 are in a portion with a high fiber density, having a greater number of fiber agglomerates fk in the middle portion 11b than in the upper portion 11a makes it easier to draw excrement from the upper portion 11a to the middle portion 11b of the absorbent core 11, i.e., from the skin side to the non-skin side in the thickness direction, and also makes it easier to prevent excrement once absorbed in the middle portion 11b from returning to the upper portion 11a.

[0096] Fig. 13 is a diagram illustrating the respective portions of the absorbent core 11 in the longitudinal and width directions. As shown in Fig. 13, when the absorbent core 11 is divided into thirds in the longitudinal direction of the napkin 1, it has, from the front side (one side) in the longitudinal direction, a front portion (one side) Ta, a central portion Tb, and a rear portion (other side) Tc. Furthermore, when the absorbent core 11 is divided into thirds in the width direction of the napkin 1, it has, from the one side, a left portion (one side) Wa, a central portion Wb, and a right portion (other side) Wc.

[0097] In such a case, it is preferable that the number of fiber agglomerates fk formed by densely packed pulverized fibers 11f in the central portion Tb be greater than the number of fiber agglomerates fk formed by densely packed pulverized fibers 11f in the front portion Ta, and that the number of fiber agglomerates fk formed by densely packed pulverized fibers 11f in the central portion Wb be greater than the number of fiber agglomerates fk formed by densely packed pulverized fibers 11f in the left portion Wa. The central portions in the longitudinal and width directions of the absorbent core 11 (the portions that are the central portions Tb and Wb) are portions that are likely to come into contact with the wearer's excretory opening, such as the vaginal opening, when worn. Therefore, having a large number of fiber agglomerates fk in the central portions Tb and Wb can improve absorbency in the portions close to the wearer's excretory opening.

[0098] ===Other Embodiments= ...

[0099] DESCRIPTION OF SYMBOLS 1 napkin (absorbent article), 1W wing portion, 10 absorbent body, 11 absorbent core, 11d central high portion, 12 core wrap sheet, 12a skin side portion (core wrap sheet), 12b non-skin side portion, 14 central compressed portion, 15 absorbent body compressed portion, 21 top sheet (surface sheet), 22 second sheet, 23 side sheet, 24 reinforcing sheet, 31 back sheet (non-skin side sheet), 32 main body adhesive portion (adhesive portion), 33 wing adhesive portion, CA crotch region, ee circular compressed portion, EL linear compressed portion

Claims

1. An absorbent article having a longitudinal direction, a width direction, and a thickness direction that are orthogonal to each other, comprising an absorbent core and a core wrap sheet provided closer to the skin side than the absorbent core, wherein the absorbent core has crushed fibers, the core wrap sheet has cellulose fibers, and the average fiber length of the crushed fibers is shorter than the average fiber length of the cellulose fibers.

2. The absorbent article according to claim 1, having a plurality of absorbent body compression portions obtained by compressing the absorbent core and the core wrap sheet in the thickness direction, wherein the length of the absorbent body compression portion in the width direction is thicker than the average fiber width of the crushed fibers, and when viewed in the thickness direction, the absorbent body compression portion and a plurality of the crushed fibers have an overlapping portion.

3. The absorbent article according to claim 2, having a central compression portion and a plurality of the absorbent body compression portions obtained by compressing the absorbent core and the core wrap sheet in the thickness direction, wherein the central compression portion is provided along the longitudinal direction and at the central portion in the width direction, and a plurality of the absorbent body compression portions are provided on both sides in the width direction of the central compression portion.

4. The absorbent article according to claim 1 or 2, wherein no adhesive is provided between the skin side surface of the absorbent core and the non-skin side surface of the core wrap sheet.

5. The absorbent article according to claim 1 or 2, wherein the absorbent core has a superabsorbent polymer, and the cellulose fibers have an average fiber length that is larger than the average value of the diameters of the superabsorbent polymer in a state not immersed in physiological saline and smaller than the average value of the diameters of the superabsorbent polymer in a state after being immersed in physiological saline for 60 minutes and then drained for 15 minutes.

6. The absorbent article according to claim 1 or 2, wherein the core wrap sheet has an overlapping portion where the core wrap sheets overlap on the skin side of the absorbent core, and no adhesive is provided between the core wrap sheets in the overlapping portion, the overlapping portion is provided at the central portion in the width direction and along the longitudinal direction, the length of the overlapping portion in the width direction is longer than the average fiber length of the pulverized fibers, and the length of the overlapping portion in the width direction is longer than the average fiber length of the cellulose fibers.

7. The absorbent article according to claim 1 or 2, wherein the weight ratio of the fibers along the longitudinal direction among the pulverized fibers is larger than the weight ratio of the fibers along the longitudinal direction among the cellulose fibers.

8. The absorbent article according to claim 1 or 2, wherein the average fiber width of the pulverized fibers is larger than the average fiber width of the cellulose fibers.

9. The absorbent article according to claim 1 or 2, having a plurality of absorber squeezing portions obtained by squeezing the absorbent core and the core wrap sheet in the thickness direction, and a non-squeezing portion where the absorbent core and the core wrap sheet overlap as viewed in the thickness direction and no absorber squeezing portion is provided, and the number of fiber masses having a density higher than the average density of the absorbent core and in which the pulverized fibers are concentrated in the non-squeezing portion of the absorbent core is larger than the number of fiber masses having a density higher than the average density of the core wrap sheet and in which the cellulose fibers are concentrated in the non-squeezing portion of the core wrap sheet.

10. The absorbent article according to claim 9, wherein the number of fiber masses having a density higher than the average density of the core wrap sheet and in which the cellulose fibers are concentrated in the non-squeezing portion of the core wrap sheet is zero.

11. The absorbent article according to claim 1 or 2, comprising: a plurality of absorber squeezing portions obtained by squeezing the absorbent core and the core wrap sheet in the thickness direction; and a non-squeezing portion that is a portion where the absorbent core and the core wrap sheet overlap when viewed in the thickness direction and where no absorber squeezing portion is provided. In the non-squeezing portion of the absorbent core, there is a fiber mass having a density higher than the average density of the absorbent core and in which the crushed fibers are concentrated. The absorbent core has a skin-side portion, an intermediate portion, and a non-skin-side portion when the absorbent core is divided into three equal parts in the thickness direction. The absorbent article is characterized in that the number of fiber masses in which the crushed fibers are concentrated in the intermediate portion is larger than the number of fiber masses in which the crushed fibers are concentrated in the skin-side portion.

12. The absorbent article according to claim 1 or 2, comprising: a plurality of absorber squeezing portions obtained by squeezing the absorbent core and the core wrap sheet in the thickness direction; and a non-squeezing portion that is a portion where the absorbent core and the core wrap sheet overlap when viewed in the thickness direction and where no absorber squeezing portion is provided. In the non-squeezing portion of the absorbent core, there is a fiber mass having a density higher than the average density of the absorbent core and in which the crushed fibers are concentrated. When the absorbent core is divided into three equal parts in the longitudinal direction and the width direction, it has a one-side portion, a central portion, and the other-side portion in order from one side. The absorbent article is characterized in that the number of fiber masses in which the crushed fibers are concentrated in the central portion is larger than the number of fiber masses in which the crushed fibers are concentrated in the one-side portion.

13. The absorbent article according to claim 1 or 2, wherein the crushed fibers include hardwood fibers made of hardwood, and the weight ratio of the hardwood fibers to the crushed fibers is 85% or more.

14. The absorbent article according to claim 1 or 2, wherein the core wrap sheet contains a paper strength enhancer, and the absorbent core does not contain the paper strength enhancer.

Images