Absorbent article

Abstract

To provide an absorbent article which hardly causes side leakage.SOLUTION: The absorbent article includes a top sheet, a back sheet, and an absorbent layer disposed between the top sheet and the back sheet, and is divided into a front region, an intermediate region, and a back region along a longitudinal direction. The intermediate region is provided with a compressed groove extending in the longitudinal direction in which the surface sheet and the absorber are integrally compressed. The compressed groove has a first region and second regions that are regions in front of and behind the first region in the longitudinal direction. The first region is provided with a raised portion raised above the second region in the thickness direction. In the projection, a first high density part and a first low density part are alternately arranged in the longitudinal direction. The distance in the thickness direction between the skin-side surface of the first high-density portion and a reference point on the skin-side surface of the top sheet in a third region in which the compressed groove is not provided is longer than the distance between the skin-side surface of the first low-density portion and the reference point. The skin-side surface of the first high-density portion has a shorter distance from the reference point in the thickness direction than the skin-side surface of the second region.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Generally, absorbent articles such as sanitary napkins are provided with compressed grooves formed by integrally compressing the topsheet and absorbent body (see Patent Documents 1 to 3). The compressed grooves are recessed from the topsheet toward the non-skin side. The compressed grooves are high-density regions where the constituent fibers are compressed, and when absorbed liquid is diffused in the width direction of the absorbent article and reaches the compressed grooves, they prevent the liquid from flowing outward in the width direction of the compressed grooves, allowing the liquid to diffuse vertically and preventing lateral leakage.

[0003] Patent Document 1 describes an absorbent article having a pair of first compressed grooves extending in the longitudinal direction of the absorbent article and a pair of second compressed grooves formed widthwise on either side of the pair of first compressed grooves. The first compressed grooves have low-compression sections as first compressed sections, and medium- and high-compression sections as second compressed sections. The first compressed grooves have the first and second compressed sections alternately arranged in the longitudinal direction. The low-compression sections are thicker than the medium- and high-compression sections. In the absorbent article described in Patent Document 1, the regions of the first compressed grooves where the low-compression sections are formed do not block the diffusion of liquid in the width direction, and liquid is more likely to diffuse toward the second compressed grooves located widthwise outward of the first compressed grooves. This expands the region in the width direction in which the absorbent body absorbs liquid, improving the absorption efficiency of the absorbent body and suppressing the longitudinal flow of liquid that is not fully absorbed by the absorbent body.

[0004] Patent Document 2 describes an absorbent article in which compressed grooves are formed through low basis weight portions and high basis weight portions of the absorbent body. Patent Document 3 describes an absorbent article that uses an absorbent body containing fiber agglomerates so that the absorbent body has excellent shape retention and maintains a good fit and comfortable fit even when worn for a long period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-18480 A [Patent Document 2] Japanese Patent Application Publication No. 2019-187645 [Patent Document 3] Japanese Patent Publication No. 2022-54307 Summary of the Invention [Problem to be solved by the invention]

[0006] Because the compressed grooves are recessed toward the non-skin side, gaps are likely to form between the wearer's skin and the absorbent article. In the absorbent article described in Patent Document 1, the low-compression section of the first compressed groove is thick, but is less rigid than the medium-compression section and the high-compression section, and is crushed by repeated application of compressive force in the thickness direction when worn, creating gaps between the wearer's skin and the absorbent article, which may result in side leakage.

[0007] The present invention relates to an absorbent article that is less susceptible to side leakage. [Means for solving the problem]

[0008] An absorbent article according to one embodiment of the present invention comprises a top sheet, a back sheet, and an absorbent layer disposed between the top sheet and the back sheet, and is divided into a front region, a middle region, and a rear region along the longitudinal direction. The intermediate region is provided with compression grooves extending in the longitudinal direction where the topsheet and the absorbent layer are compressed together. The compressed groove has a first region and second regions which are regions before and after the first region in the longitudinal direction. The first region is provided with a raised portion that rises higher in the thickness direction than the second region. In the raised portion, first high density portions and first low density portions are alternately arranged in the longitudinal direction. The skin side of the first high density portion has a longer thicknesswise distance from a predetermined reference point on the skin side of the top sheet in the third region, which is an area where the compressed grooves are not provided, than the skin side of the first low density portion. The distance in the thickness direction between the skin side surface of the first high-density portion and the reference point is shorter than that between the skin side surface of the second region and the skin side surface of the first high-density portion. [Effects of the Invention]

[0009] According to the absorbent article of the present invention, it is possible to provide an absorbent article that is less susceptible to side leakage. [Brief explanation of the drawings]

[0010] [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. 3 is a partially enlarged plan view of the absorbent article, illustrating the configuration of the central compressed groove. [Figure 6] This is a schematic, partially enlarged cross-sectional view of the portion along line VI-VI, which is an approximately L-shaped dotted line connecting the area along the central compressed groove in Figure 5 and the area extending in a direction perpendicular to the tangent to the central compressed groove, and is a figure that explains the uneven state of the skin-side surface of the top sheet caused by the central compressed groove. [Figure 7] FIG. 10 is a partially enlarged plan view illustrating the configuration of a central compressed groove as a modified example. [Figure 8] FIG. 10 is a plan view illustrating the range of the intermediate region in a long-length absorbent article. [Figure 9](A) is a plan view of an absorbent article showing the position of a test piece S cut from a napkin when measuring the surface shape of the absorbent article, (B) is a plan view of the test piece S, and (C) is an example of the unevenness profile of the surface shape of the test piece S. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] <Overall structure of absorbent article>

[0013] 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 closest to the wearer's skin may be referred to as the upper or skin side, and the side closest 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 "inner side in the transverse direction Y" refers to the side closer to the transverse direction Y of the longitudinal centerline CL1 that bisects the transverse direction Y of the napkin 1, and the term "outer side in the transverse direction Y" refers to the side away from the longitudinal centerline CL1 in the transverse direction Y. Further, "outside in the longitudinal direction X" means the side away from the horizontal center line CL2 that bisects the longitudinal direction X of the napkin 1 in half.

[0014] As shown in FIG. 1, the napkin 1 includes a main body M and a pair of wings W. Generally, absorbent articles are individually packaged in a folded state by wrapping them in a packaging sheet (not shown). The napkin 1 shown in FIG. 1 is a tri-fold type, and in the individually packaged napkin 1, the napkin 1 is folded in the longitudinal direction X around two folding portions L1 and L2 along the lateral direction Y as folding axes. The region sandwiched between the two folding portions L1 and L2 includes an excretory region that faces the excretory region of the wearer when worn.

[0015] 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 refers to the region sandwiched between the two folded portions L1 and L2. The middle region M2 includes an excretory region facing region that faces the wearer's excretory region when worn. The excretory region facing region is located at the center of the middle region M2 in the lateral direction Y. When the absorbent article is a napkin, the excretory region is the vaginal opening. The middle region M2 is also the region where the wings W are provided. The front region M1 is located in front of the middle region M2 (toward the wearer's abdomen) and faces the front of the wearer's excretory area when worn. The front region M1 is located in front of the folded portion L1. The rear region M3 is located behind the middle region M2 (toward the wearer's back) and faces the rear of the wearer's excretory area when worn. The rear region M3 is located behind the folded portion L2, which is located at the rear. 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.

[0016] 8, which is designed to have a relatively long length in the vertical direction (for example, a total length of 30 cm or more), is folded in the vertical direction X when in an individually wrapped state, around three folding portions L1, L2, and L3 along the horizontal direction Y as folding axes. In this type of napkin 1A, the area sandwiched between two adjacent folding portions L1 and L2 and including the excretory area facing area is defined as the middle area M2, as in the case of napkin 1. Similarly, in a napkin without wings, the area sandwiched between two adjacent folding portions and including the excretory area facing area is defined as the middle area.

[0017] 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.

[0018] 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.

[0019] 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 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, which are formed by bonding with an adhesive or heat sealing, or by compression processing, as shown in Figure 1. When there is no particular distinction between the central compressed groove 20, the front lateral compressed groove 31, the first rear compressed groove 32, and the second rear compressed groove 33, they may be referred to as "compressed grooves." Note that the compressed grooves are not shown in Figure 2.

[0020] 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.

[0021] 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.

[0022] 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 includes an absorbent layer 7 that absorbs liquid from the surface facing the topsheet 2 and diffuses and retains the liquid inside. 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. Details of the absorbent body 4 will be described later.

[0023] [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 located forward of the central compressed grooves 20, a first rear compressed groove 32 located rearward within the area between the pair of central compressed grooves 20, and a second rear compressed groove 33 located rearward of the pair of central compressed grooves 20. 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.

[0024] As shown in Figures 4 to 6, 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 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 from the skin side 26a of the topsheet 2 of the third region 26.

[0025] (Central compression groove) As shown in Figure 1, the napkin 1 has a pair of left and right central compressed grooves 20 that extend continuously linearly in the longitudinal direction X in the middle region M2. The pair of left and right central compressed grooves 20 are symmetrical with respect to the longitudinal center line CL1. The central compressed grooves 20 are provided in a continuous linear fashion as a whole, passing through the middle region M2 and also through parts of the front region M1 and the rear region M3 located in front and behind the middle region M2.

[0026] In the intermediate region M2, a central compressed groove 20 is provided in the region 25. The central compressed groove 20 has a first region 21 and a second region 23. The second region 23 is a region located before and after the first region 21 in the longitudinal direction X. In Fig. 5 and Fig. 7, which will be described later as a modified example, the first region 21 is indicated by dense dots, and the second region 23 is indicated by sparse dots.

[0027] As shown in Fig. 6, the first region 21 is a region where raised portions 28 that rise higher in the thickness direction Z than the second region 23 are provided. The second region 23 is more compressed than the first region 21, and has a relatively higher fiber density than the first region 21. In this embodiment, as shown in Fig. 5, two raised portions 28 are provided in each of the left and right central compressed grooves 20, for a total of four raised portions 28.

[0028] 5 and 6, in the first region 21 where the raised portions 28 are located, first high-density portions 210 and first low-density portions 211 are alternately arranged in the longitudinal direction X. Note that "alternate" here means that a pair of first high-density portions 210 and first low-density portions 211 is provided on both sides of one of the first high-density portions 210 and the first low-density portions 211 in the longitudinal direction X. In the example shown in the figures, the first high-density portions 210 have a circular shape in a plan view, and a plurality of them (three in this embodiment) are intermittently arranged in the longitudinal direction X, and the first low-density portions 211 are positioned so as to surround these first high-density portions 210. In other words, the first low-density portions 211 are positioned between the two first high-density portions 210 that are closest to each other along the central compressed groove 20, i.e., between adjacent first high-density portions 210. The first high-density portions 210 are more compressed and have higher rigidity than the first low-density portions 211. 6, the skin side surface 210a of the first high-density portion 210 is located lower (closer to the backsheet) than the skin side surface 211a of the first low-density portion 211. In this embodiment, the distance e in the thickness direction Z between the skin side surface 210a of the first high-density portion 210 and a predetermined reference point on the skin side surface 26a of the third region 26 is longer than the distance d in the thickness direction Z between the skin side surface 211a of the first low-density portion 211 and the skin side surface 26a of the third region 26. A relatively long distance from the skin side 26a of the third region 26 means that the depth of the compressed groove based on the skin side 26a of the third region 26 is relatively deep, indicating that the position is farther from the wearer's skin when the napkin is worn. If the skin-side surface 26a is flat, such as when the topsheet 2 in the middle region M2 is flat, the distances d and e are uniquely determined. In other words, regardless of where a reference point is set on the skin-side surface 26a of the topsheet 2 in the third region 26 where no compressed grooves are located, the distance between the reference point and the compressed grooves (first high-density section, first low-density section, second high-density section, second low-density section) in the thickness direction Z (the depth of the compressed groove depression as seen from the reference point) will be the same. However, if the skin-side surface 26a of the topsheet 2 in the middle region M2 is not flat, such that the thickness of the skin-side surface 26a is not constant, the "distances d and e from the skin-side surface 26a of the third region 26" are measured using a specific reference point for each of the left and right central compressed grooves 20. As an example of the reference point, the intersection point P of the longitudinal centerline and the widthwise centerline of the middle region M2 can be used, as shown in Figure 5.

[0029] As shown in FIGS. 5 and 6, in the second region 23, second high-density portions 230 and second low-density portions 231 are alternately arranged in the vertical direction X. In the example shown in the figures, the second high-density portions 230 have a circular shape in a plan view and are arranged intermittently in the vertical direction X, and the second low-density portions 231 are positioned so as to surround the peripheries of these second high-density portions 230. In other words, the second low-density portions 231 are positioned between adjacent second high-density portions 230. The second high-density portions 230 are more compressed than the second low-density portions 231, and are therefore more rigid than the second low-density portions 231. As shown in FIG. 6, the skin side surface 230a of the second high-density portions 230 is positioned lower than the skin side surface 231a of the second low-density portions 231. The distance g in the thickness direction Z between the skin side 230a of the second high density portion 230 and the skin side 26a of the third region 26 is longer than the distance f in the thickness direction Z between the skin side 231a of the second low density portion 231 and the skin side 26a of the third region 26.

[0030] As shown in FIG. 6, the raised portions 28 provided in the first region 21 are raised so as to be positioned generally higher (closer to the topsheet) than the second region 23. Whether or not the napkin 1 is "raised" can be determined visually by fixing the napkin 1 in an unfolded state on a flat and horizontal base. The skin side 210a of the first high-density portion 210 is closer to the skin side 26a of the third region 26 in the thickness direction Z than the skin side of the second region 23 (the skin side 230a of the second high-density portion 230 and the skin side 231a of the second low-density portion 231). In other words, the skin side 210a of the first high-density portion 210, which has the deepest depression among the raised portions 28, is positioned closer to the skin side (higher) than the skin side 231a of the second low-density portion 231, which has the shallowest depression among the second region 23.

[0031] The relative magnitude relationship of the distances d to g from the reference point in the third region 26 of the first and second high-density regions 210, 230 and the first and second low-density regions 211, 231 in each of the first region 21 and the second region 22 can also be evaluated as follows. First, as shown in Figures 9(A) and (B), a test strip S (shown by the thick dashed line in Figure 9(A)) is cut from the napkin 1, with a length of 60 mm in the vertical direction and a width of 30 mm (e.g., 30 mm) adjusted to fit the central compressed groove 20. This test strip S is placed on a horizontal table without pressure, with the topsheet 2 facing up. Next, the surface profile of the surface to be measured on the pressurized test strip is measured using a high-precision shape measurement system KS-1100 manufactured by Keyence Corporation. The measurement conditions are a measurement pitch of 50 μm and a movement speed of 10 cm / s. An area of ​​30 mm in the vertical direction and 30 mm in the horizontal direction is measured so that the raised portion 28 of the first region 21 and the second region 23 are both included in the measurement range. For example, as shown in Figure 9(B), at least one line (reference numeral 40) including a raised portion and at least one line (reference numeral 41) including a non-raised portion are measured along the width direction, and respective unevenness profiles are obtained as shown in Figure 9(C). The measurement results (images) obtained in this way are analyzed using the shape analysis application KS-Analyzer manufactured by Keyence Corp. This provides a surface shape profile, which makes it possible to evaluate the relative magnitude relationship of the above-mentioned distances d to g by comparing the first region 21 and the second region 23.

[0032] 5, in the napkin 1, in the central compressed groove 20, first regions 21 where the raised portions 28 are provided and second regions 23 where the raised portions 28 are not provided are arranged alternately in the longitudinal direction X. In the first regions 21, first high-density portion groups made up of a plurality of first high-density portions 210 arranged intermittently in the longitudinal direction X are arranged inside first low-density portions 211 that extend linearly overall in the longitudinal direction X. In the second regions 23, second high-density portion groups made up of a plurality of second high-density portions 230 arranged intermittently in the longitudinal direction X are arranged inside second low-density portions 231 that extend linearly overall in the longitudinal direction X.

[0033] The planar shapes of the first high density portions 210 and the second high density portions 230 are not limited to circular but may be any shape, and the multiple high density portions may have different sizes and / or shapes. The number of first high density portions 210 in the raised portion 28 (first region 21) is not particularly limited and may be one or more. The second region 23 is typically longer in the vertical direction X than the first region 21, and the number of second high density portions 230 in the second region 23 is not limited but is typically multiple.

[0034] (Action and effect) In the napkin 1 of this embodiment, by providing the raised portion 28, the raised portion 28 and its vicinity fill the gap between the napkin 1 and the wearer's skin (preventing gaps from occurring), improving the fit to the wearer's skin and suppressing side leakage. In addition, since the skin side of the second region 23 (the skin side 230a of the second high density portion 230 and the skin side 231a of the second low density portion 231) is located lower than the skin side 210a of the first high density portion 210 of the first region 21, the liquid absorbed in the raised portion 28 (first region 21) moves downward due to gravity and is more likely to diffuse into the second region 23, and the liquid that moves to the second region 23 is diffused vertically in the second region 23, which is long in the vertical direction X and has a high fiber density (hereinafter, this may be referred to as the ``vertical liquid diffusion effect due to gravity''), thereby effectively suppressing lateral leakage.

[0035] Furthermore, in the napkin 1, the skin side 210a of the first high density portion 210, which is located at the lowest of the raised portions 28, is located closer to the skin (higher) than the skin side of the second region 23, which makes it easier to ensure the height of the raised portions 28 (the height in the thickness direction Z from the skin side 231a of the second low density portion 231 of the second region 23; equivalent to the value obtained by subtracting the distance d from the distance f in Figure 6), thereby improving the effectiveness of preventing gaps from occurring.

[0036] Here, for example, if the skin side surface 210a of the first high-density portion 210 is located closer to the skin (lower) than the skin side surface 231a of the second low-density portion 231 that is located closest to the skin (upper) in the second region 23, the difference in height between the first region 21 where the raised portion 28 is provided and the second region 23 where the raised portion 28 is not provided becomes small. In other words, the distance in the thickness direction Z to the skin side surface 26a of the third region 26 becomes almost the same between the first region 21 and the second region 23, the height of the raised portion 28 becomes low, and the gap generation prevention effect cannot be achieved.

[0037] In contrast, in the napkin 1, the skin side 210a of the first high-density portion 210 is located closer to the skin (higher) than the skin side of the second region 23, and therefore, compared to when it is located on the non-skin side (lower), it is easier to create a difference in height between the first region 21 where the raised portion 28 is provided and the second region 23 where the raised portion 28 is not provided, and it is easier to ensure the height of the raised portion 28. Moreover, in the napkin 1, the highly rigid first high-density portions 210 are arranged in the raised portions 28, which increases the rigidity of the raised portions 28 and makes the raised portions 28 highly resistant to compression. Therefore, when the raised portions 28 are repeatedly subjected to compressive force in the thickness direction Z during wear, the skin-side surface 210a of the highly rigid first high-density portions 210 absorbs this compressive force, and the raised portions 28 are not compressed below the skin-side surface 210a, so that the raised portions 28 are likely to maintain their shape while ensuring a sufficient height to exert their gap-preventing effect. This makes it easier to maintain the gap-preventing effect even when worn for long periods of time.

[0038] Furthermore, in the napkin 1, in addition to the first high-density portion 210, the first low-density portion 211 is arranged in the raised portion 28, so that the first low-density portion 211 gives the raised portion 28 an appropriate softness, preventing the wearer from feeling uncomfortable when wearing it, and the first high-density portion 210 can maintain the shape of the raised portion 28 well.

[0039] In this way, the napkin 1 is likely to maintain the shape of the raised portion 28 even when worn for long periods of time, so the effect of preventing gaps from occurring and the effect of vertical diffusion of liquid due to gravity are effectively exerted, thereby continuously suppressing side leakage and providing the wearer with a comfortable fit.

[0040] (Dimensions of the raised part) The total length of raised portion 28 in the vertical direction X can be, for example, approximately 10 mm or less. From the perspective of reducing the gap between the raised portion 28 and the wearer's skin to improve fit to the skin while vertically diffusing liquid in central compressed groove 20 and effectively preventing lateral leakage, it is preferable that the total length of raised portion 28 in the vertical direction X be 5% or more and 20% or less of the total length of central compressed groove 20 located in middle region M2 (in this embodiment, this is equivalent to the distance in the vertical direction X between front folded portion L1 and rear folded portion L2).

[0041] From the viewpoint of achieving a good gap prevention effect and maintaining the height of the raised portion 28 well even when worn, it is preferable that the height of the raised portion 28 (corresponding to the value obtained by subtracting the distance d from the distance f in Figure 6) be 0.5 mm to 3.0 mm, the distance in the thickness direction Z between the skin side surface of the second region 23 and the skin side surface 210a of the first high-density portion 210 (corresponding to the value obtained by subtracting the distance e from the distance f in Figure 6) be 0.1 mm to 2.0 mm, and the distance in the thickness direction Z between the skin side surface 211a of the first low-density portion 211 and the skin side surface 26a of the third region 26 (corresponding to the distance d in Figure 6) be 0.1 mm to 2.0 mm.

[0042] (Arrangement of the first high-density section and the second high-density section) As shown in Figures 1 and 5, in the napkin 1 of this embodiment, an example has been given in which a plurality of first high-density portions 210 and a plurality of second high-density portions 230 are arranged intermittently at equal widths approximately along the longitudinal direction X, but this is not limited to this.

[0043] For example, as in a modified example shown in Figure 7, two or more (three in Figure 7) first high density portions 210 may be arranged in the first region 21 where the raised portion 28 is provided, approximately along the longitudinal direction X, and two or more second high density portions 230 may be arranged in the second region 23, approximately along the longitudinal direction X, so that when the napkin 1 is viewed in a plane, the shortest distance h between adjacent first high density portions 210 in the raised portion 28 (first region 21) is shorter than the shortest distance j between adjacent second high density portions 230 in the second region 23.

[0044] With this configuration, the raised portions 28 can be designed to have higher resistance to compression in the thickness direction Z when the napkin is worn, and thus higher shape retention, than the second regions 23. This makes it easier to maintain the difference in height between the first regions 21 where the raised portions 28 are provided and the second regions 23 where the raised portions 28 are not provided (in other words, it makes it easier to maintain the height of the raised portions 28), making it easier to achieve the effect of improving the vertical diffusion of liquid due to gravity.

[0045] (Shape of the central compression groove) 5, the central compressed grooves 20 preferably extend continuously throughout the entire length of the longitudinal direction X in the intermediate region M2, and consist of a pair of left and right central compressed grooves spaced apart in the transverse direction Y, with the central portions in the longitudinal direction X curving convexly outward in the transverse direction Y. The pair of left and right central compressed grooves 20 each have a maximum width portion 29 where the distance in the transverse direction Y is the longest.

[0046] By shaping the central compressed groove 20 in this way, the raised portion 28 is positioned above the curved central compressed groove 20, and in a plan view, the longitudinal direction of the raised portion 28 is inclined with respect to the vertical direction X. With this shape, when the raised portion 28 receives an external force directed inward in the horizontal direction Y from the wearer's thighs while worn, it is less likely to buckle and deform than when the central compressed groove is parallel to the vertical direction X (i.e., when the longitudinal direction of the raised portion is parallel to the vertical direction X), thereby improving compression resistance against the external force directed inward in the horizontal direction Y. This makes it easier for the shape of the raised portion 28 to be maintained when worn, and more reliably achieves the effect of preventing gaps from occurring and the effect of vertically diffusing liquid due to gravity.

[0047] (Shape of the central compression groove and its position relative to the raised part) Furthermore, the raised portions 28 are preferably arranged on the front or rear side in the longitudinal direction X of the maximum width portion 29 of the pair of central compressed grooves 20. In the example shown in FIG. 5, the raised portions 28, 28 are arranged on the front and rear sides in the longitudinal direction X, sandwiching the maximum width portion 29. In addition, in the maximum width portion of the central compressed groove 20 of this embodiment, a second region 23 where no raised portion 28 is provided is located, and no raised portion 28 (first region 21) is located. The raised portions 28 (first region 21) are provided in regions with widths b and c that are shorter than the width a (dimension in the lateral direction Y) of the maximum width portion 29. For example, in the example shown in FIG. 5, the width a of the maximum width portion is 55 mm, width b is 53 mm, and width c is 51 mm.

[0048] When the pair of central compressed grooves 20 are subjected to an external force directed inward in the lateral direction Y by the wearer's thighs, the greatest force is received at the portion that forms maximum width portion 29. Therefore, raised portion 28 receives the external force directed inward in the lateral direction Y after it has been weakened by second region 23 located at the portion of maximum width portion 29, so deformation of raised portion 28 can be suppressed, the shape of raised portion 28 can be more easily maintained, and the effect of preventing gaps from occurring and the effect of vertically diffusing liquid due to gravity can be more reliably achieved.

[0049] <Absorbent structure>

[0050] As shown in Figure 2, the absorbent body 4 includes an absorbent layer 7. The absorbent body 4 may further include a compression-recovery layer 8 and a core wrap sheet 6. In the absorbent body 4, the absorbent layer 7 is located on the skin side, and the compression-recovery layer 8 is located on the non-skin side. In Figure 2, the absorbent layer 7 and the compression-recovery layer 8 are each depicted as being surrounded by a solid line, but this is merely a line drawn for the sake of clarity to indicate the extent of each layer, and does not represent a specific component. Furthermore, although the absorbent layer 7 and the compression-recovery layer 8 are depicted as having gaps between both sides in the lateral direction Y and the core wrap sheet 6, this is merely a drawing for the sake of clarity to indicate the relationship between each layer and the core wrap sheet 6; in reality, no gaps exist.

[0051] The absorbent layer 7 mainly contributes to absorbing and retaining liquid. The compression recovery layer 8 contributes to improving the flexibility, cushioning, compression recovery, and shape retention of the absorbent body 4. The core wrap sheet 6 contributes to the shape retention of the absorbent body 4 by stably maintaining the laminated state of the absorbent layer 7 and the compression recovery layer 8. The compression recovery layer 8 has an extremely small amount of liquid absorption and retention compared to the absorbent layer 7, thereby ensuring the above-mentioned effects. Each component will be explained in detail below.

[0052] [Absorbing layer] As shown in Fig. 1, the absorbent layer 7 has a shape that is long in the longitudinal direction X in a 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 layer 7 has a shape that is uniform in width over the entire length in the longitudinal direction X. The outer shape of the absorbent layer 7 in a plan view is the same as that of the absorbent body 4.

[0053] The absorbent 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. Examples of superabsorbent polymers that can be used include those conventionally used in this type of absorbent body, without particular limitation, and include, for example, polymers or copolymers of acrylic acid or alkali metal acrylates.

[0054] The absorbent 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 layer 7 can be manufactured by a conventional method using a known stacking device equipped with a rotating drum. On the other hand, a sheet type absorbent core typically comprises superabsorbent polymer particles fixed to the interior or surface of a fibrous sheet, and is also called a water-absorbent sheet. Examples of the fibrous sheet include paper and nonwoven fabric. A sheet type absorbent core is thinner and more flexible than a stacked fiber type absorbent layer. A sheet type absorbent layer may, for example, comprise two opposing fibrous sheets with superabsorbent polymer particles interposed between them.

[0055] In this embodiment, as shown in FIG. 2, the absorbent layer 7 includes absorbent fibers 70 and highly absorbent polymers 71.

[0056] (absorbent fiber) 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.

[0057] (Super absorbent polymer) The highly water-absorbent polymer 71 is a surface-crosslinked polymer material known as a super absorbent polymer (SAP), and has excellent water absorption and liquid retention properties. The highly water-absorbent polymer 71 absorbs and retains liquid.

[0058] 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.

[0059] [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 layer 7. The compression-resilient layer 8 is disposed between the absorbent layer 7 and the backsheet 3. Due to its high compression-resilience, even when compressive pressure is applied in the thickness direction Z from the wearer during wear, the compression-resilient layer 8 generates a force that attempts to restore the original shape before compression, 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. As a result, even under conditions in which gaps are generally likely to form between the wearer's skin and the napkin 1, such as during strenuous exercise or when worn for long periods of time, the compression-resilience of the compression-resilient layer 8 reduces the likelihood of gaps forming between the wearer's skin and the napkin 1, improving the fit to the wearer's skin and effectively reducing liquid leakage. Furthermore, by arranging the compression-resilience layer 8 closer to the skin than the absorbent layer 7, liquid is prevented from reaching the compression-resilience layer 8, which prevents a decrease in fit and compression-resilience due to liquid accumulation in the compression-resilience layer 8, and the compression-resilience effect of the compression-resilience layer 8 is easily achieved even after the napkin 1 has absorbed liquid. The compression-resilience will be described later.

[0060] (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 layer 7. From the perspective of comfortable wear, 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 wear. Furthermore, by not providing a compressed and resilient layer in the front region M1 and the rear region M3, an increase in thickness due to the placement of a compressed and resilient layer can be avoided. This prevents stiffness due to increased thickness in the front and rear regions of the napkin 1, improving the comfort of 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. The area near the front step is close to the folded portion L1, and the area near the rear step is close to the folded portion L2. As a result, the front region M1 of the napkin 1 is easily bent toward the wearer's stomach due to the area near the front step and the folding portion L1, and the rear region M3 is easily bent toward the wearer's back due to the area near the rear step and the folding portion L2, making it easier for the napkin 1 to deform to fit the shape of the wearer's body.

[0061] 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 approximately the same dimension (width) as the absorbent layer 7 in the lateral direction Y and overlaps the absorbent 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.

[0062] (Positional relationship between the compression recovery layer and the raised part of the central compression groove) 5, it is preferable that the raised portion 28 provided in the central compressed groove 20 overlaps with the compression-recovery layer 8 in a plan view. With this configuration, the compression-recovery properties of the compression-recovery layer 8 can be utilized to easily maintain the height of the raised portion 28 and to more effectively prevent gaps from occurring.

[0063] 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 80, 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. 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. The compression-recovery layer 8 preferably has a water retention rate of 8% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, as will be described later.

[0064] (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. Hydrophobic fibers preferably have a moisture content of 3% or less, particularly 1% or less, as measured by the "Method for Measuring Moisture Content of Fiber Agglomerates" described below. When the mass of the fiber agglomerates is small and moisture content measurement is difficult, they may be measured as an aggregate of multiple fiber agglomerates. For example, multiple fiber agglomerates weighing approximately 5 g may be collected and their moisture content measured. 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 shape of the fiber aggregate. 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 body 4.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] In order to prevent liquid from accumulating in the compression-recovery layer 8 and maintain good compression-recovery properties 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] (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 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.

[0077] (Regarding compression recovery) Compression recovery can be evaluated using the compression work load (hereinafter also referred to as "WC") and recovery work load (hereinafter also referred to as "WC'") as indicators. WC is an indicator of the cushioning properties of the object being measured (here, the absorbent layer and the compression recovery layer), and the larger the WC value, the better the cushioning of the object being measured, and therefore the better the compression recovery. WC' is an indicator of the recovery properties (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, and the larger the WC' value, the better the compression recovery of the object being measured. WC and WC' are each measured by the following methods.

[0078] ((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:

[0079] 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 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 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.

[0080]

number

[0081]

number

[0082] 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).

[0083]

number

[0084] (Cross-sectional shape near the first area of ​​the central compression groove) 1 and 4, a pair of left and right central compressed grooves 20 are formed on the topsheet 2 side of the main body M. As described above, the central compressed grooves 20 are formed by compressing the topsheet 2 side in the thickness direction Z.

[0085] As shown in Figure 4, in the middle region M2, the central compressed groove 20 has a configuration in which the topsheet 2 and the absorbent body 4 are integrally recessed toward the backsheet 3. More specifically, the central compressed groove 20 is formed by integrally compressing the topsheet 2, the upper core wrap sheet 6, the absorbent layer 7, and a portion of the compressed and recoverable layer 8.

[0086] As shown in Figure 4, in the intermediate region M2, the central compression groove 20 does not reach the non-skin side 8b of the compression recovery layer 8, and the compression recovery layer 8 has a non-compressed region 86 that has not been compressed by compression processing, at least on the non-skin side 8b. The compression-recovery layer 8 has a non-compressed region 86 on the non-skin side 8b at a position overlapping the protuberances 28 in a plan view, which is not compressed to the absorbent layer 7 by compression processing and exhibits high compression-recovery properties. This prevents the protuberances 28 from pressing against the skin, preventing gaps from forming between the protuberances 28 and the wearer's skin, even when the wearer is actively active, resulting in an excellent fit to the skin. Furthermore, even when the protuberances 28 are subjected to a compressive force in the thickness direction Z, the wearer is less likely to feel uncomfortable when wearing the garment. Furthermore, since the central compression groove 20, which overlaps with the compression recovery layer 8 in a planar view, has a non-compressed area 86, in a planar view there is an area across the entire area where the compression recovery layer 8 exists that has not been compressed by the compression process, and the compression recovery effect of the compression recovery layer 8 can be well expressed across the entire area.

[0087] Furthermore, as shown in Figure 4, in the middle region M2, the compression recovery layer 8 may further have a compression region 85 that is compressed integrally with the core wrap sheet 6 and absorbent layer 7 located above on the skin side 8a. The compression-recovery layer 8 has a compressed region 85 on the skin-side surface 8a at a position overlapping the raised portion 28 in a plan view, which is compressed and bonded integrally to the topsheet 2 and the absorbent layer 7 by compression processing. This increases the rigidity of the raised portion 28 (first region 21) by the amount of highly compressively recoverable material integrated, compared to a case where a compression groove is formed in which only the topsheet 2, the upper core wrap sheet 6, and the absorbent layer 7 are compressed and bonded integrally. This increases the compression resistance of the raised portion 28 against compressive forces applied in the thickness direction Z and improves its shape retention. Combined with the effect of providing the non-compressed region 86 described above, this achieves both compression resistance of the raised portion 28 and a good fit by preventing gaps from occurring. Furthermore, the central compressed groove 20, which is formed by integrating the compressed areas 85 of the top sheet 2, upper core wrap sheet 6, absorbent layer 7, and compression recovery layer 8, can prevent undesirable deformation such as kinking of the napkin 1 when worn.

[0088] The non-compressed regions 86 of the first region 21 in which the raised portions 28 are provided are relatively thicker in the thickness direction Z than the non-compressed regions 86 of the second region 23. The non-compressed regions 86 of the first high-density portion 210 are relatively thinner in the thickness direction Z than the non-compressed regions 86 of the first low-density portion 211. The non-compressed regions 86 of the second high-density portion 230 are relatively thinner in the thickness direction Z than the non-compressed regions 86 of the second low-density portion 231.

[0089] The compressed region 85 of the first region 21 in which the raised portion 28 is provided is relatively thinner in the thickness direction Z than the compressed region 85 of the second region 23. The compressed region 85 of the first high density portion 210 is relatively thicker in the thickness direction Z than the compressed region 85 of the first low density portion 211. The compressed region 85 of the second high density portion 230 is relatively thicker in the thickness direction Z than the compressed region 85 of the second low density portion 231.

[0090] Furthermore, in the central compressed groove 20, the compressed regions may reach the non-skin side 8b of the compressed and recovering layer 8 due to the compression process, and there may be some areas where the compressed and recovering layer 8 does not have non-compressed regions 86 and is composed only of compressed regions 85. For example, during manufacturing, it is unavoidable that the supply of material forming the compressed and recovering layer is unevenly distributed within the surface and locally reduced, resulting in areas without non-compressed regions 86, but such areas are acceptable. In this case, from the perspective of achieving a good fit to the wearer, it is preferable that the non-compressed regions 86 occupy at least 50% of the area of ​​the region where the compressed and recovering layer 8 is present and where the central compressed groove 20 is provided, in a plan view.

[0091] Even in the compressed grooves that do not overlap with the compressed recovery layer 8 in a planar view (part of the central compressed groove 20, the front lateral compressed groove 31, the first rear compressed groove 32, and the second rear compressed groove 33), the compression process causes the top sheet 2 and the absorbent layer 7 to recess integrally toward the back sheet 3 on the top sheet 2 side of the napkin 1.

[0092] (Position of fiber mass in the compression area) In Figure 4, for convenience, some of the multiple fiber agglomerates 80 present in the compressed region 85 of the compressed region 25 are shown with dense dots and are labeled with the symbol 80C, and some of the multiple fiber agglomerates 80 present in the third region 26, which is the region not compressed, are shown with sparse dots and are labeled with the symbol 80D.

[0093] As shown in FIG. 4, the fiber agglomerates 80 in the compression region 85 preferably include fiber agglomerates 80C that are arranged from the compression region 85 to the third region 26 and that are arranged so that their skeletal surfaces 81 are inclined with respect to the thickness direction Z.

[0094] As described above, the skeletal surfaces 81 are more easily entangled than the base surfaces 82, and therefore, when the fiber agglomerates 80C assume the above-described orientation, the skeletal surfaces 81 of the fiber agglomerates 80C are more likely to be entangled in the thickness direction Z with the fiber agglomerates 80D in the third region 26 than when the skeletal surfaces 81 are perpendicular to the thickness direction Z. As a result, when the raised portions 28 are subjected to a compressive force in the thickness direction Z, the fiber agglomerates 80C, with their skeletal surfaces 81 inclined at an angle, can distribute the pressure to the entangled fiber agglomerates 80D across the thickness direction Z, thereby improving the compression resistance of the raised portions 28.

[0095] [Core Wrap Sheet] The core wrap sheet 6 is a sheet member that encases the absorbent layer 7 and the compression-recovery layer 8. The core wrap sheet 6 encases the entire absorbent layer 7 and the compression-recovery layer, which are stacked in order in the thickness direction Z, and has the function of holding each layer together and maintaining the shape of each stacked layer. The core wrap sheet 6 is formed, for example, from thin, soft paper like tissue paper or a liquid-permeable nonwoven fabric.

[0096] The absorbent layer 7 and the compression-recovery layer 8, which are wrapped in the core wrap sheet 6, are not bonded to each other with adhesive, and no adhesive is contained within each layer. By wrapping the absorbent layer 7 and the compression-recovery layer 8 together with the core wrap sheet 6, the integrated laminated state of each layer is maintained and the shape of the absorbent body 4 can be maintained without using adhesive between or within each layer.

[0097] [Additional absorber configuration] A liquid-retaining layer containing at least one of a water-absorbent sheet and a highly water-absorbent polymer may be disposed between the compression-recovery layer of the absorbent body and the core wrap sheet disposed on the non-skin-facing side. The liquid retention layer 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 retention layer are more preferably 8% or more and 12% by mass or more, respectively, and particularly preferably 10% and 15% by mass or more. The moisture content of the liquid retention layer can be determined by measuring in the "Method for measuring the moisture content of a fiber mass" described below, substituting "liquid retention layer" for "fiber mass." The moisture retention rate of the liquid retention layer can be determined by measuring in the "Method for measuring the moisture content of a compressed and restored layer" described below, substituting "liquid retention layer" for "compressed and restored layer."

[0098] (Method for measuring moisture content of fiber mass) In this specification, the term "water absorbency" is easily understood by those skilled in the art, for example, pulp is water absorbent. The degree of water absorbency of a fiber mass can also be determined by the moisture content measured by the following method.

[0099] 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

[0100] (Method for measuring the water retention rate of the compressed and restored layer) The water retention rate of the compressed and decompressible layer can be measured by the following method. Specifically, the compressed and decompressible layer to be measured is removed. The compressed and decompressible 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.

[0101] <Method of forming compression grooves>

[0102] The compressed grooves are formed by covering the skin-facing side of the absorbent body 4 with the topsheet 2, and then compressing the topsheet 2 and the absorbent body 4 from the side of the topsheet 2. Below, we will explain the method for manufacturing the absorbent body 4 and the method for forming the compressed grooves, in that order.

[0103] 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 layer-forming material (absorbent fiber 70, superabsorbent polymer 71) and the compressed and recovering layer material (fiber mass 80) 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 order of the absorbent layer 7 and the compressed and recovering layer 8 in the absorbent body 4 can be realized by appropriately adjusting the stacking order of the respective forming materials on the rotating drum in the manufacturing method using the fiber stacking device.

[0104] 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 to stack and integrate a fiber stack (absorbent layer 7) produced by one fiber stacking device with a fiber stack (compressed recovery layer 8) produced by the other fiber stacking device, and then cover the integrated laminate 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 (fiber mass 80) forming the compressed recovery layer 8 to the accumulation recess is different from that of the material (absorbent fiber 70, superabsorbent polymer 71) forming the absorbent layer 7, to produce a laminate of the absorbent layer 7 and the compressed recovery layer 8, and then the laminate is covered with a core wrap sheet 6.

[0105] Next, an example of a method for forming compressed grooves will be described. Compressed grooves can be produced by pressing and heating a laminate including the topsheet 2 and the absorbent body 4 together between an embossing roll having projections and recesses and a flat roll having a flat peripheral surface.

[0106] The uneven shape of the first region 21 where the raised portions 28 are provided and the second region 23 where the raised portions 28 are not provided on the skin side of the topsheet 2 in the central compressed groove 20 shown in Figure 6 can be formed by utilizing the height of the convex portions provided on the surface of the embossing roll. Specifically, the magnitude relationship between the heights of the convex portions of the embossing roll that respectively form the first low-density portion 211 of the raised portions 28 (first region 21), the first high-density portion 210 of the raised portions 28 (first region 21), the second low-density portion 231 of the second region 23, and the second high-density portion 230 of the second region 23 can be set as follows. Convex portions forming the first low-density portion < convex portions forming the first high-density portion < convex portions forming the second low-density portion < convex portions forming the second high-density portion

[0107] Furthermore, the formation of the compressed regions 85 and non-compressed regions 86 below the raised portions 28 can be adjusted by adjusting the conditions (embossing conditions) when pressing the roll, such as the clearance between the embossing roll and the flat roll and the roll temperature, when the embossing roll is pressed against the surface (topsheet) side of the article including the topsheet and absorbent on the production line. More specifically, the clearance between the rolls and the embossing conditions are adjusted so that the convex portions forming the first low-density portions 211 of the raised portions 28 on the embossing roll do not cause the raised portions 28 to reach the non-skin side 8b of the compressed-recovery layer 8.

[0108] <Other embodiments>

[0109] 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.

[0110] 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]

[0111] 1, 1A... Napkins, sanitary napkins (absorbent articles) 2...Surface sheet 3...Back sheet 7...Absorption layer 20...Central compression groove (compression groove) 21...First area 210…1st high density part 210a...Skin side of the first high density area 211...1st low density part 23…Second area 230…Second high density part 230a...Skin side of the second high-density area (skin side of the second area) 231…Second low density part 231a...Skin side of the second low-density area (skin side of the second area) 26...Third area (area where no compression grooves are provided) 26a...skin side of the surface sheet of the third region 28...Protuberance P…Reference point

Claims

1. An absorbent article comprising a top sheet, a back sheet, and an absorbent layer disposed between the top sheet and the back sheet, and divided into a front region, a middle region, and a rear region along a longitudinal direction, The intermediate region is provided with compression grooves extending in the longitudinal direction, in which the topsheet and the absorbent layer are integrally compressed, The compression groove has a first region and a second region which is a region before and after the first region in the longitudinal direction, The first region is provided with a raised portion that is raised upward in the thickness direction relative to the second region, In the raised portion, first high density portions and first low density portions are alternately arranged in the longitudinal direction, the skin side of the first high density portion has a longer distance in the thickness direction from a predetermined reference point on the skin side of the topsheet in a third region, which is a region where the compressed grooves are not provided, than the skin side of the first low density portion; a distance in a thickness direction between the skin side surface of the first high-density portion and the reference point is shorter than a distance between the skin side surface of the second region and the reference point; Absorbent articles.

2. The absorbent article according to claim 1, In the second region, second high-density portions and second low-density portions are alternately arranged in the longitudinal direction, a skin side surface of the second high density portion has a longer distance in a thickness direction from the reference point than a skin side surface of the second low density portion; Two or more of the first high-density portions are arranged in the raised portion, two or more second high-density portions are arranged in the second region, In a plan view, the shortest distance between adjacent first high-density portions in the raised portion is shorter than the shortest distance between adjacent second high-density portions in the second region. Absorbent articles.

3. The absorbent article according to claim 1 or 2, The compressed grooves extend continuously over the entire longitudinal length of the intermediate region, and are formed of a pair of left and right compressed grooves spaced apart in the width direction and convexly curved outward in the width direction. Absorbent articles.

4. The absorbent article according to claim 3, The raised portion is arranged on the front region side or the rear region side in the longitudinal direction of a portion of the pair of compressed grooves that is a maximum width portion where the distance in the width direction is the longest. Absorbent articles.

5. The absorbent article according to claim 1 or 2, A compression recovery layer is further provided between the absorbent layer and the backsheet, The compression recovery layer includes, in a region overlapping with the protrusion in a plan view, a non-compressed region on the non-skin side that is not compressed with the absorbent layer by the compression process that forms the compression grooves. Absorbent articles.

6. The absorbent article according to claim 5, The compression recovery layer includes a compressed region that is compressed integrally with the absorbent layer by the compression process, the compressed region being closer to the skin side than the non-compressed region in a region that overlaps with the protrusion in a plan view. Absorbent articles.

7. The absorbent article according to claim 6, the compression-recovery layer is composed of a plurality of fiber agglomerates having two opposing basic surfaces and a skeletal surface connecting the two basic surfaces; The fiber agglomerates in the compression region are arranged from the compression region to the third region, and are arranged so that the skeletal surface is inclined with respect to the thickness direction. Absorbent articles.

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