Absorbent article

Abstract

To provide an absorbent article capable of suppressing both liquid return and an overflow phenomenon in a surface sheet containing cellulose fiber.SOLUTION: An absorbent article includes a surface sheet, a back sheet, and an absorber, and is divided into an intermediate region, a front region, and a rear region in a longitudinal direction. The surface sheet contains first cellulose fibers and second cellulose fibers having higher hydrophilicity than that of the first cellulose fibers, and is composed of a nonwoven fabric in which the first cellulose fibers and the second cellulose fibers are mixed. The surface sheet has a plurality of low basis weight portions disposed spaced apart from each other. The absorbent article further includes a longitudinally extending central compressed portion. The central compressed portion is disposed in a central portion in the lateral direction, which is a central region obtained by dividing the intermediate region into three equal parts in the lateral direction. The central compressed portion is disposed so as to overlap the low basis weight portion in a plane view when viewed from the thickness direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an absorbent article having a topsheet containing cellulose fibers. [Background technology]

[0002] An absorbent article generally comprises a top sheet forming a skin-facing surface, a back sheet, and an absorbent body disposed between the top sheet and the back sheet. Due to growing environmental awareness and a sense of security regarding natural materials, absorbent articles having a top sheet containing cellulose fibers such as cotton fibers are known.

[0003] Topsheets containing cellulose fibers can be more hydrophilic than those containing thermoplastic fibers. Highly hydrophilic topsheets are prone to liquid return to the skin-facing surface, which can cause discomfort such as stickiness and wetness. In response to this, techniques for reducing the hydrophilicity of topsheets containing cellulose fibers are known. For example, Patent Document 1 discloses an absorbent article equipped with a topsheet in which a water-repellent agent is applied to a spunlace nonwoven fabric made of 100% cotton fibers by weight. Patent Document 2 also discloses a staple fiber nonwoven fabric used as a surface material for sanitary products, which contains unabsorbed cotton as a constituent fiber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-169926 [Patent Document 2] Patent Publication No. 2021-040752 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the hydrophilicity of a topsheet containing cellulose fibers is reduced too much, the so-called overflow phenomenon occurs, in which liquid runs down the skin-facing surface, and an unpleasant wet feeling may result.

[0006] The present invention relates to an absorbent article that can suppress both liquid return and overflow phenomena in a topsheet containing cellulose fibers. [Means for solving the problem]

[0007] An absorbent article according to one embodiment of the present invention comprises a top sheet, a back sheet, and an absorbent body arranged between the top sheet and the back sheet, and has a vertical direction corresponding to the front-to-back direction of a wearer, a horizontal direction corresponding to the left-to-right direction of the wearer and perpendicular to the vertical direction, and a thickness direction perpendicular to the vertical and horizontal directions. The absorbent article comprises: In the vertical direction, the diaper is divided into an intermediate region including an excretory area facing region facing the excretory area of ​​the wearer, a front region located in front of the intermediate region in the vertical direction, and a rear region located behind the intermediate region in the vertical direction. The topsheet includes first cellulose fibers and second cellulose fibers that are more hydrophilic than the first cellulose fibers, and is made of a nonwoven fabric in which the first cellulose fibers and the second cellulose fibers are mixed. The topsheet has a plurality of low basis weight portions having a basis weight lower than that of the surrounding area. The low basis weight portions are spaced apart from one another at least in the intermediate region. The absorbent article further comprises: The absorbent body has a central compressed portion recessed in the thickness direction from the topsheet to the absorbent body and extending in the longitudinal direction. The central compressed portion is disposed in the horizontal center portion, which is the central region obtained by dividing the intermediate region into three equal parts in the horizontal direction. The central compressed portion is disposed so as to overlap the low basis weight portion in a plan view seen from the thickness direction. [Effects of the Invention]

[0008] According to the absorbent article of the present invention, it is possible to suppress both the liquid return and overflow phenomena in the topsheet containing cellulose fibers. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view of an absorbent article according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a perspective view of a nonwoven fabric constituting the topsheet of the absorbent article. [Figure 4] FIG. 2 is a plan view showing the skin-facing surface of the nonwoven fabric constituting the topsheet, illustrating an area where no compressed portions are formed. [Figure 5] FIG. 2 is an enlarged plan view of FIG. 1, showing an enlarged central compressed portion of the absorbent article. [Figure 6] FIG. 5 is an enlarged view of FIG. 4, showing an enlarged view of the low basis weight portion of the topsheet. [Figure 7] 3 is a cross-sectional view of an absorbent article according to a modified example of the embodiment, taken at the same position as in FIG. 2. FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 5 is a cross-sectional view taken along line XX in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] [Overall structure of napkins (absorbent articles)] An absorbent article 1 according to one embodiment of the present invention is, for example, a pad-type absorbent article, and more specifically, is configured as a sanitary napkin, hereinafter referred to as napkin 1. As shown in FIG. 1 , napkin 1 comprises a main body M and a pair of wing portions W. Napkin 1 has a longitudinal direction X corresponding to the front-to-back direction of a wearer, and a lateral direction Y corresponding to the left-to-right direction of the wearer and perpendicular to longitudinal direction X. Furthermore, napkin 1 has a thickness direction Z perpendicular to both longitudinal direction X and lateral direction Y. Napkin 1 can be configured, for example, to be line-symmetric (bilaterally symmetric) with respect to a longitudinal centerline CL that divides napkin 1 into two equal parts in the lateral direction Y.

[0012] In this specification, "inner side in the lateral direction Y" means the side closer to the longitudinal center line CL. "outer side in the lateral direction Y" means the side away from the longitudinal center line CL. In this specification, "front side in the longitudinal direction X" means the front in the longitudinal direction X, i.e., the direction toward the wearer's abdomen. "rear side in the longitudinal direction X" means the rear in the longitudinal direction X, i.e., the direction toward the wearer's back. In this specification, the "skin side" in the thickness direction Z means the side that is placed on the wearer's side when the napkin 1 is worn. The "non-skin side" in the thickness direction Z means the side that is placed on the clothing side when the napkin 1 is worn. In this specification, "plan view" means a plan view from the thickness direction Z.

[0013] As shown in FIG. 1, the napkin 1 is divided in the longitudinal direction X into a middle region B including a region facing the excretory part of the wearer, a front region A located in front of the middle region B, and a rear region C located behind the middle region B. In this embodiment, the excretory part is the vaginal opening. In FIG. 1, the middle region B is the region between the front and rear base ends of the wing portions W. The front region A is the region located in front of the middle region B (toward the ventral side of the wearer). The rear region C is the region located behind the middle region B (toward the dorsal side of the wearer).

[0014] The wing portions W extend outward in the lateral direction Y from the main body M in the intermediate region B. The wing portions W are used by folding them onto the non-skin-facing side of the crotch portion of underwear such as shorts. As a variation of this embodiment, the napkin 1 may not have the wing portions W. In that case, when the napkin 1 is stored in an individual package folded in the longitudinal direction X at at least two folds extending in the lateral direction Y, the region divided by the first fold located at the frontmost side in the region including the absorbent body 4 and the second fold located at the position nearest thereto is referred to as the intermediate region B, the region in front of the first fold is referred to as the front region A, and the region behind the second fold is referred to as the rear region C. These definitions apply to pad-type absorbent articles.

[0015] As shown in Fig. 2, the napkin 1 comprises a main body M, an absorbent body 4, a topsheet 2, a backsheet 3, and an intermediate sheet 5. In the example shown in Fig. 2, the napkin 1 has a configuration in which the backsheet 3, absorbent body 4, intermediate sheet 5, and topsheet 2 are layered in this order in the thickness direction Z. These components are joined together as appropriate, for example, by means of compressed grooves, adhesives, heat sealing, etc., as described below.

[0016] The absorbent body 4 is disposed between the top sheet 2 and the back sheet 3. The absorbent body 4 absorbs and retains bodily fluids (hereinafter also referred to as "liquid") such as menstrual blood from the skin side. In this embodiment, the absorbent body 4 has an absorbent core 40 and a core wrap sheet 41 that covers the absorbent core 40. The absorbent core 40 is composed of a fibrous body of absorbent fibers or a laminate of absorbent sheets, and may contain an absorbent polymer. The core wrap sheet 41 is composed of thin absorbent paper, liquid-permeable nonwoven fabric, or the like. However, the configuration of the absorbent body 4 is not limited to the example shown in the figure, and for example, it may not have a core wrap sheet.

[0017] The topsheet 2 has a skin-facing side 2a that is placed on the skin side and a non-skin-facing side 2b that is placed on the non-skin side, and is placed on the skin side of the absorbent body 4. The topsheet 2 is a liquid-permeable sheet material made of a nonwoven fabric containing cellulose fibers. The detailed structure of the topsheet 2 will be described later.

[0018] The intermediate sheet 5 is disposed between the topsheet 2 and the absorbent body 4. The intermediate sheet 5 is disposed to improve the transfer of liquid from the topsheet 2 to the absorbent body 4 and to prevent liquid absorbed in the absorbent body 4 from returning to the topsheet 2. The detailed configuration of the intermediate sheet 5 will be described later. As a variation of this embodiment, the napkin 1 may not have the intermediate sheet 5.

[0019] The backsheet 3 is placed on the non-skin side of the absorbent body 4. From the viewpoint of suppressing leakage of menstrual blood, the backsheet 3 is preferably made of a sheet material having properties such as low liquid permeability and / or water repellency. Examples of such sheet materials include a thermoplastic resin film and a laminate sheet of such a film and a nonwoven fabric. Furthermore, from the viewpoint of improving wearing comfort, the backsheet 3 is preferably breathable and / or moisture permeable.

[0020] The non-skin-facing surface 3a of the backsheet 3 may be provided with, for example, fastening parts 7 for fastening the napkin 1 to underwear. The fastening parts 7 may be arranged, for example, on the main body M and the wing parts W. The fastening parts 7 may be made of, for example, an adhesive, a pressure-sensitive adhesive, a hook material, or the like.

[0021] In the example shown in Figures 1 and 2, the napkin 1 preferably further comprises a pair of side sheets 6 from the viewpoint of improving the leakproofness of the side portions in the lateral direction Y. The pair of side sheets 6 are arranged on the outer sides of the topsheet 2 in the lateral direction Y. The material of the side sheets 6 is preferably a sheet material that is less hydrophilic than the topsheet 2, and specific examples include nonwoven fabrics, films, and laminated sheets of nonwoven fabrics and films that are less hydrophilic than the topsheet 2. The side sheets 6 and the backsheet 3 are joined to each other by known joining means such as adhesives, heat sealing, or ultrasonic sealing at the extending portions from both side edges of the absorbent body 4 along the longitudinal direction X. In the example shown, the wing portions W are formed by joining the side sheets 6 and the backsheet 3.

[0022] [Detailed composition of the surface sheet] The topsheet 2 contains first cellulose fibers and second cellulose fibers that are more hydrophilic than the first cellulose fibers, and is made of a nonwoven fabric in which the first cellulose fibers and the second cellulose fibers are mixed.

[0023] Cellulose fibers are fibers primarily composed of cellulose and are classified into, for example, natural fibers, regenerated fibers, and semi-synthetic fibers. Examples of cellulose fibers classified as natural fibers include cotton fibers and fibers other than cotton (such as flax and Manila hemp, palm, kraft pulp, and straw). Examples of cellulose fibers classified as regenerated fibers include rayon, polynosic, cupra, and lyocell. Examples of cellulose fibers classified as semi-synthetic fibers include acetate and triacetate. Of these, the cellulose fibers of this embodiment preferably contain at least one selected from cotton fiber, rayon, and lyocell because they have a pleasant feel to the touch. Cotton fiber is more preferable because it is a natural fiber and has a pleasant feel to the touch. The topsheet 2 may contain multiple types of the above-mentioned fibers as cellulose fibers.

[0024] The topsheet 2 preferably contains cellulose fiber as a main component, and specifically, the cellulose fiber content is preferably 50% by mass or more. Furthermore, the cellulose fiber content in the topsheet 2 is preferably 90% by mass or more, more preferably 95% by mass or more, and may even be 100% by mass. Furthermore, the topsheet 2 may contain fibers other than cellulose fiber (such as thermoplastic fibers, which will be described later).

[0025] The hydrophilicity of cellulose fibers can be adjusted by, for example, at least one selected from the selection of fibers used, degreasing treatment, and use of a fiber treatment agent. In this embodiment, the hydrophilicity can be adjusted by at least one selected from degreasing treatment and use of a fiber treatment agent. The degreasing treatment is a treatment to remove oils inherent in the material, which can reduce the hydrophilicity of the cellulose fibers. The fiber treatment agent includes, for example, a hydrophobizing agent capable of reducing hydrophilicity, a hydrophilizing agent capable of increasing hydrophilicity, etc.

[0026] In this embodiment, the hydrophilicity of the first cellulose fiber and the second cellulose fiber can be compared based on the contact angle between the fiber and water, and it can be determined that the smaller the contact angle, the higher the hydrophilicity. In this embodiment, the first contact angle, which is the contact angle between the first cellulose fiber and water, is larger than the second contact angle, which is the contact angle between the second cellulose fiber and water. A method for measuring the contact angle of the fiber will be described later.

[0027] The term "nonwoven fabric containing a mixture of first and second cellulose fibers" refers to a nonwoven fabric in which the first and second cellulose fibers are mixed and arranged in the same layer. Such a nonwoven fabric is produced by subjecting a web containing a mixture of the first and second cellulose fibers to a process for entangling and / or bonding the fibers. The nonwoven fabric constituting the topsheet 2 is preferably, for example, a spunlace nonwoven fabric, a needle-punched nonwoven fabric, or a resin-bonded nonwoven fabric, since these allow for entanglement and / or bonding of the cellulose fibers. A spunlace nonwoven fabric, in which the fibers are entangled by a water flow, is more preferred because of its excellent strength and appearance.

[0028] The topsheet 2 in this embodiment is made of, for example, a single-layer nonwoven fabric. The term "single-layer nonwoven fabric" means that it does not have a laminated structure formed by stacking multiple webs or multiple nonwoven fabrics.

[0029] The topsheet 2 has multiple low-basis weight sections 21 with a lower basis weight than the surrounding areas to prevent overflow and other problems (see FIGS. 3 and 4). The low-basis weight sections 21 are visually distinguishable regions with a clearly lower basis weight than the surrounding areas. When the average basis weight of 10 or more locations selected from the regions other than the low-basis weight sections 21 is taken as 100%, the low-basis weight sections 21 are regions with a basis weight of 50% or less. Furthermore, if the topsheet 2 has regions with varying basis weights, the low-basis weight sections 21 are regions classified as having the lowest basis weight. In this embodiment, examples of the low-basis weight sections 21 include regions with a thinner thickness than the surrounding areas and regions with a lower fiber density than the surrounding areas. As described below, low-fiber density regions are preferred. The low-basis weight sections 21 are regions with a relatively small amount of fibers, and therefore can be regions that are more permeable to liquid. In the examples shown in FIGS. 3 and 4, the low-basis weight sections 21 are shown as through-holes. However, when viewed microscopically, only a small number of fibers (such as the fiber section 22 described below) may be present. The planar shape of the low basis weight portion 21 is not particularly limited.

[0030] The plurality of low basis weight portions 21 are arranged spaced apart from one another at least in the intermediate region B. For example, the plurality of low basis weight portions 21 are arranged spaced apart from one another in at least one of the longitudinal direction X or the lateral direction Y, and are preferably arranged spaced apart from one another in both the longitudinal direction X and the lateral direction Y as illustrated in FIG. 1 . As illustrated in FIG. 1 , the low basis weight portions 21 are preferably aligned in both the longitudinal direction X and the lateral direction Y, but may also be arranged offset from one another in both the longitudinal direction X and the lateral direction Y. The low basis weight portions 21 may be arranged in at least the intermediate region B, but may also be arranged in the front region A and / or the rear region C.

[0031] [Configuration of the central compression section] The napkin 1 further comprises a central compressed section 8 that is recessed in the thickness direction Z from the topsheet 2 to the absorbent body 4 and extends in the longitudinal direction X. The central compressed section 8 is formed, for example, by compressing the topsheet 2 in the thickness direction Z. As shown in Figure 2, the central compressed section 8 has a configuration in which the topsheet 2, intermediate sheet 5, and absorbent body 4 are integrally recessed toward the non-skin side. When compressed, the central compressed section 8 becomes recessed from the surrounding area, making it easier for liquid to flow in and creating an area with a narrower fiber distance than the surrounding area, making it easier for liquid to diffuse due to capillary action.

[0032] The phrase "the central compressed section 8 extends in the longitudinal direction X" does not necessarily mean that the central compressed section 8 extends parallel to the longitudinal direction X, but may mean that the central compressed section 8 as a whole extends in the longitudinal direction X. The central compressed section 8 may be formed, for example, in the shape of a groove extending in the longitudinal direction X. The shape of the central compressed section 8 in a plan view (planar shape) may be, for example, linear, curved, or meandering. The central compressed section 8 may be formed in a continuous line, or may be formed as a linear compressed section as a whole by a plurality of embossed sections arranged at small intervals (for example, 4 mm or less).

[0033] The central compression section 8 is located in a horizontal central section D, which is the central region obtained by dividing the middle region B into thirds in the horizontal direction Y. In this embodiment, the "lateral central section D of the middle region B" refers to the central region obtained by dividing the middle region B of the main body M into thirds in the horizontal direction Y, and is a region that includes the excretory part-facing region. When the middle region B of the main body M is divided into thirds in the horizontal direction Y, the regions on both sides of the horizontal central section D are referred to as "lateral side sections E" (see Figures 1 and 2). As will be described later, if the napkin 1 includes outer compression sections 9 in addition to the central compression section 8, the central compression section 8 will be located more inward in the horizontal direction Y than the outer compression sections 9.

[0034] As shown in Figure 5, the central compressed section 8 is arranged to overlap the low basis weight section 21 in plan view from the thickness direction Z. "The central compressed section 8 and the low basis weight section 21 overlap in plan view" means that at least a portion of the low basis weight section 21 overlaps with the central compressed section 8 in plan view. There may be at least one low basis weight section 21 overlapping one central compressed section 8, but as will be described later, there may be multiple low basis weight sections 21 overlapping. The overlap between the central compressed section 8 and the low basis weight section 21 can be determined visually, for example, by observing with a digital microscope (e.g., VHX-6000, manufactured by Keyence) that the fibers in the low basis weight section are compacted.

[0035] [Effects of the above configuration] In the above configuration, the topsheet 2 is a nonwoven fabric made of a mixture of first cellulose fibers with low hydrophilicity and second cellulose fibers with high hydrophilicity, which reduces the hydrophilicity of the topsheet 2 and prevents liquid backflow, which is the phenomenon in which liquid that has migrated to the non-skin side of the topsheet 2 flows back to the skin-facing surface 2a. Furthermore, because the first cellulose fibers and the second cellulose fibers are mixed, even if liquid is repelled by the first cellulose fibers with low hydrophilicity, the second cellulose fibers with high hydrophilicity tend to block the liquid. This makes it easier to prevent overflow, which is the phenomenon in which excreted liquid flows over the skin-facing surface 2a.

[0036] Furthermore, in the above configuration, the central compressed section 8 is located in the laterally central section D, which includes the excretion part-facing region of the intermediate region B. Because the laterally central section D includes the excretion part-facing region, excreted liquid can flow into the recessed central compressed section 8 and spread along the central compressed section 8. Furthermore, in the above configuration, the central compressed section 8 is located so as to overlap the low basis weight section 21 in a plan view, which makes it easier for liquid spreading through the central compressed section 8 to pass through the low basis weight section 21 and migrate to the non-skin side. Therefore, in the above configuration, excreted liquid can easily migrate quickly from the low basis weight section 21 overlapping the central compressed section 8 to the non-skin side, effectively suppressing overflow.

[0037] Furthermore, in the region overlapping with the low basis weight section 21 of the central compressed section 8, the inter-fiber distance tends to be wider than in the region not overlapping with the low basis weight section 21 of the central compressed section 8. For this reason, in the region overlapping with the low basis weight section 21 of the central compressed section 8, it is possible to effectively promote the migration of highly viscous, impermeable liquids (such as menstrual blood, vaginal discharge, loose stools, etc.) to the non-skin side.

[0038] As described above, the above configuration can suppress both the liquid returning and overflow phenomena on the skin-facing surface 2a, and can effectively suppress the discomfort associated with stickiness and wet feeling when worn.

[0039] [Configuration example for multiple central compression units] The napkin 1 preferably includes a plurality of the above-mentioned central compressed sections 8, and these central compressed sections 8 are preferably arranged spaced apart from one another. In this configuration, each of the plurality of central compressed sections 8 is located in the lateral central section D, and is arranged to overlap the low basis weight section 21 in a plan view seen from the thickness direction Z. By arranging the plurality of central compressed sections 8 in the lateral central section D, the contact opportunity between excreted liquid and the central compressed sections 8 is increased, more effectively promoting the transfer of the liquid to the non-skin side. Note that, as will be described later, if the napkin 1 includes outer compressed sections 9 in addition to the central compressed sections 8, all of the plurality of central compressed sections 8 will be arranged inward in the lateral direction Y from the outer compressed sections 9.

[0040] The multiple central compression units 8 are preferably arranged spaced apart from one another in at least one of the longitudinal direction X or the transverse direction Y, and more preferably arranged spaced apart from one another in both the longitudinal direction X and the transverse direction Y. In the example shown in Fig. 1, the multiple central compression units 8 form multiple vertical columns Ln that are arranged along the longitudinal direction X and spaced apart from one another in the transverse direction Y. Each vertical column Ln is a column in which multiple central compression units 8 are arranged spaced apart from one another in the longitudinal direction X. In the same figure, an example is shown in which the multiple central compression units 8 form three vertical columns Ln, one at the center of the napkin 1 in the longitudinal direction X (for example, on the longitudinal center line CL) and one on either side of that center in the transverse direction Y, but the number and arrangement of the central compression units 8 are not limited to this example.

[0041] In the above configuration, the central compressing units 8 in one column Ln are preferably arranged so that the spacing S between the central compressing units 8 in that column Ln overlaps in the vertical direction X with the central compressing units 8 in the column Ln adjacent to that column Ln in the horizontal direction Y. In other words, if an imaginary line is drawn that passes through both ends of the spacing S in the vertical direction X (the vertical X ends of the central compressing units 8 adjacent to each other in the vertical direction X) and is parallel to the horizontal direction Y, at least one central compressing unit 8 in the adjacent column Ln is arranged so that it partially overlaps with the region between these imaginary lines. With this configuration, liquid that flows in the horizontal direction Y through the spacing S can be directed into the central compressing unit 8 in the adjacent column Ln, thereby preventing liquid from overflowing in the horizontal direction Y.

[0042] [Configuration example regarding the arrangement of the central compression section and low basis weight section] Furthermore, it is preferable that the central compressed section 8 overlaps, in plan view, two or more of the plurality of low basis weight sections 21. The central compressed section 8 may overlap three or more low basis weight sections 21, as exemplified in Figure 5. The presence of multiple low basis weight sections 21 overlapping with the central compressed section 8 can promote the migration of liquid to the non-skin side in the central compressed section 8, and more effectively suppress overflow.

[0043] [Detailed example of low basis weight section] The low basis weight portion 21 preferably has a low fiber density to ensure the liquid transfer function, and is preferably configured to prevent the topsheet 2 from changing shape even after contact with liquid. From this perspective, the low basis weight portion 21 of this embodiment preferably includes a fiber portion 22 and void portions 23, as shown in Fig. 6.

[0044] The fibrous portion 22 is a portion of the low basis weight portion 21 that includes the first cellulose fibers F1 and the second cellulose fibers F2. In the fibrous portion 22, the first cellulose fibers F1 and the second cellulose fibers F2 are preferably entangled. In this embodiment, the presence of the fibrous portion 22 and the entanglement of the first cellulose fibers F1 and the second cellulose fibers F2 can be confirmed when observed at a magnification of 50 times. In FIG. 6, the first cellulose fibers F1 are represented as black fibers and the second cellulose fibers F2 are represented as white fibers, but these colors are used to distinguish the fibers and do not represent their actual colors. In addition, fibers arranged around the low basis weight portion 21 are omitted from the figure.

[0045] The voids 23 are portions of the low basis weight portion 21 that do not contain fibers. In other words, the voids 23 are regions of the low basis weight portion 21 excluding the fiber portion 22. The arrangement of the voids 23 is not particularly limited, and as exemplified in Fig. 6, the voids 23 may form minute through-holes in a plan view. Alternatively, the voids 23 may not be open in a plan view, but may be voids adjacent to the fiber portion 22 in the thickness direction Z.

[0046] In the above configuration, the low-strength low-basis weight portion 21 of the topsheet 2 includes the fibrous portion 22, so that even if the fibers surrounding the low-basis weight portion 21 swell after contact with liquid and become prone to shape change, the fibrous portion 22 can suppress shape change of the low-basis weight portion 21. Furthermore, the fibrous portion 22 includes the first cellulose fibers F1 and the second cellulose fibers F2 that are entangled with each other, so that the highly hydrophilic second cellulose fibers F2 promote liquid transfer to the non-skin side, while the less hydrophilic first cellulose fibers F1 suppress loosening of the entanglement due to swelling of the fibrous portion 22. Therefore, the low-basis weight portion 21 configured as described above suppresses shape change of the low-basis weight portion 21 due to swelling in liquid when worn, and continuously promotes liquid transfer via the low-basis weight portion 21.

[0047] From the viewpoint of promoting the migration of liquid to the non-skin side in the low basis weight portion 21, it is preferable that the void portion 23 be formed by an opening penetrating in the thickness direction Z. In this case, from the viewpoint of promoting the inflow of liquid, the area of ​​the opening is preferably 0.01 mm 2 More than 0.02mm, preferably 0.02mm 2 From the viewpoint of ensuring the strength of the top sheet 2, it is preferable that the thickness is 0.30 mm or more. 2 Less than or equal to 0.80 mm, preferably 2 The area of ​​the apertures is the average area of ​​the dark regions in a binarized image taken at 50x magnification with a digital microscope (e.g., VHX-6000, manufactured by Keyence) with the non-skin-facing surface of the topsheet 2 placed on a flat surface. The imaging conditions are brightness auto 70, gain preset 0dB, white balance 255, epi-illumination ON, and ring illumination ON. The threshold for binarization processing is -58.

[0048] [Example of cellulose fiber composition] In this embodiment, from the viewpoint of preparing cellulose fibers with different hydrophilicities, it is preferable that the first cellulose fibers are primarily composed of undefatted fibers and the second cellulose fibers are primarily composed of defatted fibers. Undefatted fibers refer to cellulose fibers that have not been subjected to a defatting treatment, and defatted fibers refer to cellulose fibers that have been subjected to a defatting treatment. The expression "the first cellulose fibers are primarily composed of undefatted fibers" means that the first cellulose fibers contain undefatted fibers as the fiber body, and includes, for example, a configuration in which the first cellulose fibers are composed of undefatted fibers and a configuration in which the first cellulose fibers contain undefatted fibers and a fiber treatment agent. Similarly, the expression "the second cellulose fibers are primarily composed of defatted fibers" means that the second cellulose fibers contain defatted fibers as the fiber body, and includes, for example, a configuration in which the second cellulose fibers are composed of defatted fibers and a configuration in which the second cellulose fibers contain defatted fibers and a fiber treatment agent. By using defatted fibers and undefatted fibers, the hydrophilicity of the first cellulose fibers and the second cellulose fibers can be reliably and easily adjusted.

[0049] Preferred examples of the hydrophilicity of cellulose fibers are described below. The first contact angle, which is the contact angle between the first cellulose fibers and water, is preferably 89° or less. The second contact angle, which is the contact angle between the second cellulose fibers and water, is preferably 60° or less and smaller than the first contact angle. By setting the first and second contact angles within the above ranges, the hydrophobicity of the first cellulose fibers can be reduced and the hydrophilicity of the second cellulose fibers can be sufficiently increased. This allows the overflow phenomenon in the topsheet 2 to be sufficiently suppressed. Furthermore, from the viewpoint of more reliably suppressing the overflow phenomenon in the topsheet 2, the upper limit of the first contact angle is more preferably 84° or less, and even more preferably 79° or less. From the same viewpoint, the upper limit of the second contact angle is more preferably 55° or less, and even more preferably 50° or less.

[0050] Regarding the lower limit of the contact angles, the first contact angle is preferably 60° or more. The second contact angle is preferably 20° or more and smaller than the first contact angle. By setting the first contact angle and the second contact angle within the above ranges, it is possible to effectively suppress liquid return on the topsheet 2. From the viewpoint of more reliably suppressing liquid return on the topsheet 2, the lower limit of the first contact angle is more preferably 65° or more, and even more preferably 70° or more. From the same viewpoint, the lower limit of the second contact angle is more preferably 25° or more, and even more preferably 30° or more.

[0051] (Method for measuring contact angle of fiber) Fibers are removed from a designated location on the nonwoven fabric, and the contact angle of water with the fibers is measured. The measurement device used is an automatic contact angle meter MCA-J (product name) manufactured by Kyowa Interface Science Co., Ltd. Distilled water is used for measuring the contact angle. The amount of liquid ejected from the inkjet water droplet ejection unit (CTC-25 pulse injector with a 25 μm nozzle diameter manufactured by Cluster Technology Co., Ltd.) is set to 10 picoliters, and the water droplets are dropped directly onto the fibers. The dropping behavior is recorded on a high-speed recording device connected to a horizontally placed camera. For later image analysis, a personal computer equipped with a high-speed capture device is preferable as the recording device. In this measurement, images are recorded every 17 msec. In the recorded video, the first image of a water droplet landing on a fiber removed from the nonwoven fabric is analyzed using the accompanying software FAMAS (software version 2.6.2, analysis method: sessile drop method, analysis method: θ / 2 method, image processing algorithm: non-reflective, image processing image mode: frame, threshold level: 200, no curvature correction), and the angle between the surface of the water droplet in contact with the air and the fiber is calculated, which is taken as the contact angle. If the fiber removed from the nonwoven fabric is 2 mm long or longer, it is cut to a fiber length of 2 mm and placed on the sample stage of the contact angle meter, maintaining it horizontal. The contact angle is measured at three different points for each fiber, and the average value (rounded to two decimal places) is defined as the contact angle.

[0052] The first and second cellulose fibers may contain a hydrophilizing agent and / or a hydrophobizing agent to adjust their hydrophilicity. When the first and second cellulose fibers are composed of undefatted and defatted fibers, the contact angles of the first and second cellulose fibers tend to be lower than the preferred range of contact angles described above. Therefore, it is preferable that the first and second cellulose fibers contain a hydrophobizing agent that reduces hydrophilicity. The hydrophobizing agent is not particularly limited, and conventionally known hydrophobizing agents, such as paraffin-based and silicone-based agents, can be used. It is also preferable that the first and second cellulose fibers contain the same hydrophobizing agent.

[0053] Furthermore, in order to adjust the balance between suppressing liquid return and suppressing overflow in the topsheet 2, it is preferable to adjust the content ratio of the second cellulose fibers to the first cellulose fibers. Specifically, in the topsheet 2, the mass ratio P / Q, which is the ratio of the content P of the first cellulose fibers to the content Q of the second cellulose fibers, is preferably 1 / 9 or more and 1 or less. This optimizes the balance between suppressing liquid return and suppressing overflow in the topsheet 2, allowing both effects to be exerted. Furthermore, from the viewpoint of more reliably exerting the above-mentioned effects, the mass ratio P / Q is preferably 1 / 7 or more, more preferably 1 / 5 or more, and preferably 2 / 3 or less, more preferably 1 / 2 or less.

[0054] [Example of intermediate sheet configuration] Furthermore, the napkin 1 of this embodiment preferably includes an intermediate sheet 5 disposed between the topsheet 2 and the absorbent body 4. In this case, the intermediate sheet 5 preferably contains primarily thermoplastic fibers. By disposing the intermediate sheet 5 between the topsheet 2 and the absorbent body 4, liquid that has permeated the topsheet 2 can be temporarily retained, facilitating the transfer of liquid from the topsheet 2 to the non-skin side. The liquid retention ability of the intermediate sheet 5 also prevents liquid from returning to the topsheet 2. Note that "the intermediate sheet 5 contains primarily thermoplastic fibers" means that the thermoplastic fiber content is 50% by mass or more, where the mass of the intermediate sheet 5 is 100% by mass. Furthermore, the thermoplastic fiber content of the intermediate sheet 5 is preferably 75% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass. The intermediate sheet 5 may contain one or more types of thermoplastic fibers.

[0055] Thermoplastic fibers are fibers primarily made of thermoplastic resin, specifically fibers containing 50% or more by mass of thermoplastic resin. The thermoplastic resin content of thermoplastic fibers is preferably 75% or more by mass, more preferably 90% or more by mass, and even more preferably 95% or more by mass. Examples of thermoplastic resins include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid, polymethacrylic acid alkyl esters, polyvinyl chloride, and polyvinylidene chloride. Thermoplastic fibers may be single fibers or composite fibers made of one type of thermoplastic resin or a blend polymer of two or more types of thermoplastic resins. The composite fiber may have any of various configurations, including sheath-core and side-by-side types. Because the thermoplastic resin exerts the above-mentioned effects, its hydrophilicity can be adjusted by using a fiber treatment agent or the like.

[0056] Specifically, the intermediate sheet 5 can be made of a nonwoven fabric. Examples of such nonwoven fabrics include air-through nonwoven fabrics, spunbond nonwoven fabrics, resin-bond nonwoven fabrics, spunlace nonwoven fabrics, and air-laid nonwoven fabrics. From the viewpoint of enhancing liquid retention by utilizing the spaces between fibers, air-through nonwoven fabrics or air-laid nonwoven fabrics are preferred.

[0057] Furthermore, when the low basis weight section 21 has the above-mentioned fiber section 22, it is preferable that, in the low basis weight section 21 arranged overlapping the central compression section 8, at least one of the first cellulose fibers F1 or the second cellulose fibers F2 of the fiber section 22 is in contact with the thermoplastic fibers of the intermediate sheet 5. This configuration makes it easier for liquid that has flowed into the low basis weight section 21 to migrate along the fiber section 22 to the intermediate sheet 5, more effectively suppressing the overflow phenomenon on the topsheet 2. The above configuration is formed, for example, by compressing the topsheet 2 and intermediate sheet 5, including the above-mentioned fiber section 22, in the thickness direction Z during compression processing, thereby bringing the fiber section 22 and the thermoplastic fibers of the intermediate sheet 5 closer together.

[0058] Furthermore, from the viewpoint of promoting liquid migration, it is more preferable that at least one of the first cellulose fibers F1 or the second cellulose fibers F2 of the fiber portion 22 is entangled with the thermoplastic fibers of the intermediate sheet 5. This configuration allows liquid that has flowed into the low basis weight portion 21 to be more reliably transferred to the intermediate sheet 5, and more effectively prevents overflow onto the topsheet 2. The above configuration can be achieved, for example, by heating the topsheet 2, intermediate sheet 5, etc. while applying pressure in the thickness direction Z during compression processing, thereby increasing the flexibility of the thermoplastic fibers to an extent that they can be entangled with other fibers.

[0059] [Example of outer compression section configuration] As described above, the inter-fiber distance is narrower in the compressed section than in the surrounding area, making it easier for liquid to diffuse due to capillary action. The topsheet 2 in this embodiment can suppress overflow by using the above-mentioned central compressed section 8 and low basis weight section 21, but from the perspective of further increasing the sense of security against liquid leakage in the lateral direction Y, it is preferable that the napkin 1 also include outer compressed sections 9 located outside the central compressed section 8 in the lateral direction Y.

[0060] In this embodiment, the outer compressed sections 9 are formed, for example, by compressing the topsheet 2 in the thickness direction Z, similar to the central compressed section 8. In this embodiment, the outer compressed sections 9 are recessed in the thickness direction Z from the topsheet 2 to the absorbent body 4, and extend in the longitudinal direction X. As a result, as shown in Figure 2, the outer compressed sections 9 cause the topsheet 2, intermediate sheet 5, and absorbent body 4 to be recessed together toward the non-skin side.

[0061] The phrase "the outer compressed portions 9 extend in the longitudinal direction X" does not necessarily mean that the outer compressed portions 9 extend parallel to the longitudinal direction X, but may mean that the outer compressed portions 9 extend in the longitudinal direction X as a whole. The outer compressed portions 9 may be formed, for example, in the shape of grooves extending in the longitudinal direction X. The shape of the outer compressed portions 9 in a plan view (planar shape) may be, for example, linear, curved, or meandering. The outer compressed portions 9 may be formed in a continuous line, or may be formed as a linear compressed portion as a whole by a plurality of embossed portions arranged at small intervals (for example, 4 mm or less).

[0062] In the above configuration, the outer compressed portions 9 are positioned outward in the lateral direction Y from the central compressed portion 8. When the topsheet 2 comprises multiple central compressed portions 8, "the outer compressed portions 9 are positioned outward in the lateral direction Y from the central compressed portion 8" means that the outer compressed portions 9 are positioned more outward in the lateral direction Y than the central compressed portion 8 that is positioned furthest outward in the lateral direction Y from the longitudinal centerline CL among the multiple central compressed portions 8. Furthermore, the outer compressed portions 9 are preferably positioned in the intermediate region B, on the lateral side portions E on both sides in the lateral direction Y of the lateral center portion D (see Figures 1 and 2). By positioning the outer compressed portions 9 outward in the lateral direction Y from the central compressed portions 8, even if liquid spreads outward in the lateral direction Y from the central compressed portions 8 due to the wearer's movements, etc., the liquid can be spread in the longitudinal direction X along the outer compressed portions 9, thereby suppressing liquid leakage in the lateral direction Y of the topsheet 2.

[0063] In this embodiment, the outer compressed portions 9 preferably have a larger dimension in the longitudinal direction X than the central compressed portion 8. When the topsheet 2 comprises multiple central compressed portions 8, "the outer compressed portions 9 have a larger dimension in the longitudinal direction X than the central compressed portion 8" means that the dimension in the longitudinal direction X of the outer compressed portions 9 is larger than that of the central compressed portion 8 that has the largest dimension in the longitudinal direction X among the multiple central compressed portions 8. The outer compressed portions 9 preferably extend in the longitudinal direction X across the entire middle region B, and preferably extend further into the front region A and / or rear region C. By making the outer compressed portions 9 longer in the longitudinal direction X than the central compressed portions 8, it is possible to suppress liquid leakage from the topsheet 2 in the transverse direction Y, even if liquid spreads in front of and behind the central compressed portion 8 due to the wearer's movements, etc.

[0064] In this embodiment, from the viewpoint of suppressing liquid leakage on both the left and right sides, it is preferable that the napkin 1 is provided with a pair of outer compressed portions 9. Furthermore, from the viewpoint of suppressing liquid leakage along the entire periphery of the main body M, it is more preferable that the pair of outer compressed portions 9 are connected to each other in the front region A and / or the rear region C. In this case, the pair of left and right outer compressed portions 9 extend toward each other inward in the lateral direction Y at the front end and / or rear end. For example, by connecting the pair of outer compressed portions 9 to each other in the front region A and the rear region C, the pair of outer compressed portions 9 can be formed into a closed shape.

[0065] Furthermore, although not shown, the napkin 1 may have multiple pairs of outer compressed portions 9. In this case, it is preferable that all of the multiple pairs of outer compressed portions 9 are arranged on the lateral side portions E. Furthermore, the dimensions of the multiple pairs of outer compressed portions 9 in the longitudinal direction X may be different.

[0066] [Detailed example of the layout of the central compression section and absorbent body] As illustrated in FIGS. 1 and 2, in this embodiment, the absorbent body 4 preferably has a central portion 42 disposed in the laterally central region D. The central portion 42 is a region having a larger dimension in the thickness direction Z than the surrounding area and a higher basis weight. In the example shown in FIG. 2, the central portion 42 is a region where the absorbent core 40 protrudes toward the skin, but the absorbent core 40 may also protrude toward the non-skin side. The central portion 42 only needs to be disposed in the laterally central region D, and may partially extend to at least one of the laterally side regions E, the front region A, or the rear region C. By disposing the central portion 42 with a high basis weight in the laterally central region D, which includes the excretory-part-facing region, the absorption capacity of the absorbent body 4 can be efficiently increased. Furthermore, the central portion 42 having a large dimension in the thickness direction Z can improve the fit of the napkin 1 to the excretory part and its vicinity.

[0067] In the above configuration, the central compressed portion 8 is preferably positioned so as to overlap the central peak 42 in plan view. This allows the central compressed portion 8 to be positioned so as to fit the excretory portion and its vicinity, making it easier to guide excreted fluid to the central compressed portion 8. Furthermore, if the napkin 1 has multiple central compressed portions 8, it is preferable that all of the central compressed portions 8 are positioned so as to overlap the central peak 42 in plan view.

[0068] As a modification of this embodiment, the absorbent body 4 may not have the central peak 42, as shown in FIG.

[0069] [More detailed example of surface sheet configuration] The configuration of the topsheet 2 will be described in more detail below. The topsheet 2 preferably comprises a plurality of belt-like portions 11 and a plurality of spacing portions 12. In this embodiment, the skin-facing surface 2a of the topsheet 2 has an uneven surface, and the non-skin-facing surface 2b is a substantially flat surface. From the perspective of suppressing overflow in areas other than the areas where the central compressed portion 8 and the outer compressed portions 9 are formed, it is preferable that the skin-facing surface 2a has a characteristic uneven shape formed by the belt-like portions 11 and spacing portions 12 as shown below. Note that the configuration of the topsheet 2 described below applies to areas other than the areas where the central compressed portion 8 and the outer compressed portions 9 are formed.

[0070] Preferably, the multiple strip-shaped portions 11 are arranged spaced apart from one another in the horizontal direction Y, and are each formed in a strip shape extending in the vertical direction X in a plan view seen from the thickness direction Z. In this embodiment, "strip-shaped" refers to a shape extending in one direction and having a width in a direction perpendicular to that direction. That is, the longitudinal direction of the strip-shaped portions 11 is the vertical direction X, and the horizontal direction Y is the width direction. The strip-shaped portions 11 "extending in the vertical direction X" only need to extend in the vertical direction X as a whole, and specifically include a configuration extending linearly parallel to the vertical direction X, a configuration extending in the vertical direction X while curving, a configuration extending in the vertical direction X while meandering, and the like.

[0071] For example, the strip portion 11 may extend over a portion of the topsheet 2 in the longitudinal direction X, but from the viewpoint of ensuring the effects described below, it is preferable that the strip portion 11 extend over the entire topsheet 2 in the longitudinal direction X.

[0072] The width dimension of the strip portion 11 in the horizontal direction Y may vary locally, but is preferably constant as shown in the figure. The width dimension of the strip portion 11 in the horizontal direction Y is the average value of measurements of the width dimension taken at six or more locations along the vertical direction X at predetermined intervals (for example, about 0.4 mm). Furthermore, "the width dimension of the strip portion 11 in the horizontal direction Y is constant" means that the difference between the width measurements at these six or more locations is within 20% of the smallest measurement value.

[0073] The width dimensions of the multiple strip portions 11 arranged at different positions in the lateral direction Y may differ in part, but are preferably approximately the same. "The width dimensions of the strip portions 11 arranged at different positions in the lateral direction Y are approximately the same" means that the difference in the width dimensions of these strip portions 11 is within a range of 20% or less of the value of the smallest width dimension.

[0074] The spacing portions 12 are, for example, arranged alternately with the strip portions 11 in the horizontal direction Y, and are formed on the skin-facing surface 2a in a concave shape in the thickness direction Z relative to the strip portions 11. In this embodiment, the spacing portions 12 form gaps between the strip portions 11 and extend in the vertical direction X along the strip portions 11. That is, the vertical direction X is the longitudinal direction of the spacing portions 12, and the horizontal direction Y is the width direction.

[0075] The width dimension of the gap 12 in the horizontal direction Y is preferably constant along the vertical direction X. The width dimension of the gap 12 in the horizontal direction Y refers to the average value of measurements taken at six or more intervals along the vertical direction X at predetermined intervals (for example, about 0.4 mm). Furthermore, "the width dimension of the gap 12 in the horizontal direction Y is constant" means that the difference between the measurements at these six or more intervals is within a range of 20% or less of the smallest measurement value.

[0076] The width dimensions of the multiple spacing portions 12 arranged at different positions in the horizontal direction Y may differ in part, but are preferably approximately the same. "The width dimensions of the spacing portions 12 arranged at different positions in the horizontal direction Y are approximately the same" means that the difference in the width dimensions of these spacing portions 12 is within a range of 20% or less of the value of the smallest width dimension.

[0077] The phrase "the spacing portion 12 is formed concavely in the thickness direction Z with respect to the strip portion 11 on the skin-facing surface 2a" means that the height dimension of the spacing portion 12 is smaller than the height dimension of the strip portion 11. As will be described later, the strip portion 11 and the spacing portion 12 each have regions with different height dimensions along the vertical direction X. Therefore, the spacing portion 12 is configured so that the height dimension of all regions is smaller than the height dimension of the region of the strip portion 11 adjacent to it in the horizontal direction Y.

[0078] The "height dimension in the thickness direction Z" of each portion of the topsheet 2 refers to the dimension in the thickness direction Z from a flat surface to the skin-facing surface 2a of each portion when the non-skin-facing surface 2b is placed on the flat surface in an unloaded state, and is the average value of measurements at six or more points spaced at predetermined intervals (e.g., about 0.4 mm) along the longitudinal direction X. The height dimension of each portion can be measured, for example, by profile measurement using a laser microscope or the like.

[0079] In this embodiment, the boundary between the strip portion 11 and the spacing portion 12 is a portion that extends in the vertical direction X and passes through the midpoint of the step between the strip portion 11 and the spacing portion 12. More specifically, the boundary is a portion that passes through a height that is the average value of the maximum measured values ​​of the height dimensions of the region of the strip portion 11 and the region of the spacing portion 12 that are adjacent in the horizontal direction Y when the non-skin-facing surface 2b is placed on a flat surface.

[0080] For example, as illustrated in Figures 3 to 8, the strip portion 11 has a plurality of first regions 13 and a plurality of second regions 14, each having a different height. The first regions 13 are arranged spaced apart from one another in the vertical direction X. The second regions 14 are arranged alternately with the first regions 13 in the vertical direction X. In this embodiment, both the first regions 13 and the second regions 14 are regions formed across the entire width of the strip portion 11 in the horizontal direction Y.

[0081] 3 and 8, the second region 14 is formed on the skin-facing surface 2a so as to be concave in the thickness direction Z relative to the first region 13, from the viewpoint of guiding liquid from the first region 13 to the second region 14. "The second region 14 is formed on the skin-facing surface 2a so as to be concave in the thickness direction Z relative to the first region 13" means that the height dimension H2 of the second region 14 is smaller than the height dimension H1 of the first region 13. The boundary between the first region 13 and the second region 14 is defined as a portion passing through a height that is the average of the maximum measured value of the height dimension of the first region 13 and the maximum measured value of the height dimension of the second region 14.

[0082] The first region 13 preferably has a substantially flat surface on the skin-facing surface 2a, as illustrated in Fig. 8. Similarly, the second region 14 preferably has a substantially flat surface on the skin-facing surface 2a. The "substantially flat surface" on the skin-facing surface 2a refers to a surface in which the difference in measured height values ​​at six or more points arranged at predetermined intervals (e.g., approximately 0.4 mm) along the longitudinal direction X and / or the lateral direction Y is within a range of 20% or less of the smallest measured value.

[0083] In this embodiment, the spacing section 12 has multiple low basis weight sections 21. From the perspective of allowing liquid to flow in from the second regions 14, the low basis weight sections 21 are preferably arranged adjacent to the second regions 14 in the lateral direction Y and formed in the thickness direction Z. This allows liquid to be guided from the first regions 13 to the second regions 14, even in areas other than those where the central compressed section 8 is formed, and makes it easier for the liquid to flow into the recessed low basis weight sections 21. Furthermore, by arranging the second regions 14 so that they are sandwiched between two first regions 13, the liquid is blocked near the second regions 14, facilitating the liquid's flow into the low basis weight sections 21.

[0084] The phrase "the low basis weight portion 21 is disposed adjacent to the second region 14 in the horizontal direction Y" means that when an imaginary line is drawn parallel to the horizontal direction Y through the point of the maximum dimension of the target low basis weight portion 21 in the vertical direction X, the region between the imaginary lines overlaps with at least a portion of the second region 14 belonging to at least one of the strip portions 11 adjacent to the spacing portion 12 to which the low basis weight portion 21 belongs. In this embodiment, the ratio of the length dimension in the vertical direction X of the overlapping portion with the second region 14 to the maximum dimension in the vertical direction X of the low basis weight portion 21 is preferably 50% or more, more preferably 75%.

[0085] In this embodiment, from the viewpoints of promoting the inflow of liquid into the low basis weight portion 21 and ensuring the strength of the topsheet 2, it is preferable that the spacing portion 12 further comprises a connecting portion 16 connecting two first regions 13 adjacent to the spacing portion 12 (see FIGS. 3, 4 and 10). In this configuration, the connecting portion 16 is formed across the entire width of the spacing portion 12 in the lateral direction Y.

[0086] The spacing portions 12 having the connecting portions 16 allow fibers to exist between the first regions 13, thereby increasing the strength (particularly the tensile strength in the transverse direction Y) of the topsheet 2. Increasing the strength of the topsheet 2 can suppress deformation of the topsheet 2 and the resulting fuzzing, and is also expected to have the effect of improving wearing comfort.

[0087] From the viewpoint of suppressing the overflow phenomenon of the topsheet 2 and further increasing its strength, the spacing portions 12 preferably have a plurality of connecting portions 16. In this configuration, the connecting portions 16 are preferably arranged alternately with the low basis weight portions 21 in the longitudinal direction X. In this configuration, the low basis weight portions 21 are regularly arranged in the area surrounded by the belt-like portions 11 and the connecting portions 16, thereby enhancing the liquid flow suppression effect.

[0088] Since the connecting portion 16 belongs to the spacing portion 12, it is formed concavely in the thickness direction Z on the skin-facing surface 2a relative to the first region 13. That is, as shown in FIG. 10, the height H3 of the connecting portion 16 is smaller than the height H1 of the first region 13. From the viewpoint of ensuring the thickness and strength of the topsheet 2, it is preferable that the connecting portion 16 has a substantially flat surface on the skin-facing surface 2a, as shown in FIG. 10. The boundary between the connecting portion 16 and the first region 13 is the portion that passes through a height that is the average of the maximum measured height of the connecting portion 16 and the maximum measured height of the first region 13 when the non-skin-facing surface 2b is placed on a flat surface.

[0089] Furthermore, the two first regions 13 connected to the connection portion 16 are preferably arranged along the horizontal direction Y. "The two first regions 13 are arranged along the horizontal direction Y" refers to an arrangement in which, when two imaginary lines parallel to the horizontal direction Y are drawn passing through the center points in the vertical direction X of each of the two target first regions 13, both of these imaginary lines pass through the two first regions 13. The center point in the vertical direction X of the first regions 13 refers to the midpoint of the line segment connecting the end points of the first regions 13 that have the maximum dimension in the vertical direction X.

[0090] With the above configuration, the at least two strip-shaped portions 11 and the connecting portion 16 have, in a plan view, a lattice shape extending in the vertical direction X and the horizontal direction Y, or a planar shape similar thereto. This enhances the effect of the connecting portion 16 in improving the tensile strength in the horizontal direction Y.

[0091] In this embodiment, the first region 13 is preferably a region with a higher fiber density than the second region 14. That is, in this embodiment, the first region 13 is a region with a high fiber density and a large height dimension H1, and the second region 14 is a region with a low fiber density and a small height dimension H2. By making the second region 14 have a lower fiber density than the first region 13, it is possible to provide a localized region with a low fiber density, thereby improving the flexibility and breathability of the topsheet 2.

[0092] Similarly, in this embodiment, the first regions 13 preferably have a higher fiber density than the connection regions 16. That is, in this embodiment, the connection regions 16 also preferably have a lower fiber density and a smaller height dimension H2 than the first regions 13. This can improve the flexibility and breathability of the topsheet 2.

[0093] In this embodiment, when the fiber density of the first region 13 is taken as 100%, the ratio of the fiber density of the second region 14 is preferably 30% or more, more preferably 40% or more, from the viewpoint of suppressing deformation of the second region 14, and is preferably 95% or less, more preferably 85% or less, from the viewpoint of improving flexibility, breathability, etc. in the second region 14. When the fiber density of the first region 13 is taken as 100%, the ratio of the fiber density of the connection portion 16 is preferably 30% or more, more preferably 40% or more, and is preferably 95% or less, more preferably 85% or less, from the same viewpoint as the second region 14.

[0094] The fiber density of the first region 13 is preferably 40 fibers / mm 3 More preferably, 50 lines / mm 3 From the viewpoint of ensuring the flexibility of the topsheet 2, the number of threads / mm is preferably 300. 3 Less than or equal to 150 lines / mm, preferably 150 lines / mm 3 The fiber density of the second region 14 can be appropriately set so as to satisfy the above fiber density ratio, and is preferably 20 fibers / m 3 More preferably, 30 lines / mm 3 or more, preferably 200 lines / mm 3 Less than or equal to 150 lines / mm, preferably 150 lines / mm 3 The fiber density of the connecting portion 16 can be appropriately set to satisfy the above fiber density ratio, and is preferably 20 fibers / mm 3 More preferably, 30 lines / mm 3 or more, preferably 200 lines / mm 3 Less than or equal to 150 lines / mm, preferably 150 lines / mm 3 The following is the result.

[0095] (Method for measuring fiber density) Using a Feather Razor (product number FAS-10, manufactured by Feather Safety Razor Co., Ltd.), each measurement object (first region, second region, and joint) is cut along the thickness direction Z. The cut surface is observed under magnification using a scanning electron microscope (magnification (150-500x) that allows measurement of 30-60 fiber cross sections), and the measurement area is determined by dividing the fiber into a certain number (0.5 mm 2 ) and count the number of fiber cross sections cut by the cutting surface of 1 mm. 2 The fiber density is calculated by converting the number of fiber cross sections per unit area into the number of fiber cross sections per unit area, and this is taken as the fiber density. As the scanning electron microscope, for example, JCM-5100 (product name) manufactured by JEOL Ltd. is used.

[0096] [Examples of shapes of the first area, second area, and connecting part] The height dimension H1 of the first region 13 in the thickness direction Z is preferably 50 μm or more, and more preferably 80 μm or more, from the viewpoint of effectively exerting the liquid blocking effect of the convex first region 13. Furthermore, from the viewpoint of effectively exerting the effect of guiding liquid to the low basis weight portion 21, the height dimension H1 is preferably 800 μm or less, more preferably 700 μm or less, and even more preferably 600 μm or less.

[0097] In this embodiment, the ratio (H2 / H1) of the height dimension H2 of the second region 14 to the height dimension H1 of the first region 13, which is taken as 100%, is preferably 50% or more, more preferably 70% or more, from the viewpoint of more effectively exerting the liquid guiding effect described above, and is preferably 100% or less, more preferably 99% or less, from the viewpoint of more effectively exerting the liquid blocking effect described above. In this embodiment, the height dimension H2 of the second region 14 can be appropriately set in consideration of H2 / H1, and is preferably 50 μm or more, more preferably 100 μm or more, and is preferably 700 μm or less, more preferably 500 μm or less.

[0098] In this embodiment, the ratio (H3 / H1) of the height dimension H3 of the connecting portion 16 to the height dimension H1 of the first region 13, which is taken as 100%, is preferably 30% or more, more preferably 50% or more, from the viewpoint of more effectively exerting the liquid guiding effect described above, and is preferably 90% or less, more preferably 80% or less, from the viewpoint of more effectively exerting the liquid blocking effect described above. Furthermore, in this embodiment, the height dimension H3 of the connecting portion 16 can be appropriately set in consideration of H3 / H1, and is preferably 30 μm or more, more preferably 50 μm or more, and preferably 500 μm or less, more preferably 300 μm or less.

[0099] Furthermore, in this embodiment, the length dimension L1 of the first region 13 in the longitudinal direction X is preferably 1.0 mm or more, more preferably 1.5 mm or more, from the viewpoint of stably guiding the liquid to the low basis weight portion 21 and effectively suppressing the overflow phenomenon. Also, from the viewpoint of suppressing the overflow phenomenon on the first region 13, the length dimension L1 is preferably 20 mm or less, more preferably 10 mm or less.

[0100] Furthermore, in this embodiment, the length dimension L2 of the second region 14 in the longitudinal direction X is preferably 0.3 mm or more, and more preferably 0.6 mm or more, from the viewpoint of blocking the liquid and enhancing the liquid guideability to the low basis weight portion 21. Moreover, from the viewpoint of ensuring strength, the length dimension L2 is preferably 2.0 mm or less, and more preferably 1.5 mm or less.

[0101] The length of each portion of the topsheet 2 is the dimension in the longitudinal direction X measured in a plan view with the non-skin-facing surface 2b placed on a flat surface, and is the average value of measurements taken at six or more locations spaced at predetermined intervals (e.g., about 0.4 mm) along the transverse direction Y. The length of each portion can be measured, for example, by profile measurement using a laser microscope or the like.

[0102] Furthermore, in this embodiment, the width dimension W1 of the first region 13 in the lateral direction Y is preferably 1 mm or more, and more preferably 2 mm or more, from the viewpoint of improving the liquid guideability to the low basis weight portion 21. Moreover, the width dimension W1 is preferably 7 mm or less, and more preferably 5 mm or less, from the viewpoint of suppressing the overflow phenomenon on the first region 13.

[0103] The width of each portion of the topsheet 2 is the dimension in the horizontal direction Y measured in a plan view with the non-skin-facing surface 2b placed on a flat surface, and is the average value of measurements taken at six or more locations spaced at predetermined intervals (e.g., about 0.4 mm) along the vertical direction X. The width of each portion can be measured, for example, by profile measurement using a laser microscope or the like.

[0104] Furthermore, in this embodiment, the width W2 of the connection portion 16 in the lateral direction Y is preferably 0.3 mm or more, more preferably 0.5 mm or more, from the viewpoint of ensuring a sufficient area for blocking the liquid. Moreover, the width W2 is preferably 2.0 mm or less, more preferably 1.5 mm or less, from the viewpoint of ensuring strength, etc.

[0105] The basis weight of the top sheet 2 is preferably 20 g / m 2 More preferably, 25 g / m 2 From the viewpoint of enhancing liquid permeability and flexibility, it is preferably 80 g / m 2 Less than 70 g / m 2 The basis weight of the topsheet 2 is the average basis weight of three rectangular test pieces with sides 8 cm along the longitudinal direction X and sides 7 cm along the transverse direction Y. The basis weight is calculated by measuring the mass of the test piece and dividing this mass by the area. If it is not possible to obtain a test piece of the above size because the area of ​​the nonwoven fabric to be measured is small, for example, a test piece with as large an area as possible is cut out.

[0106] The thickness of the topsheet 2 is preferably 0.1 mm or more, more preferably 0.2 mm or more, from the viewpoint of ensuring strength, and preferably 1.0 mm or less, more preferably 0.9 mm or less, from the viewpoint of improving liquid permeability and flexibility. The thickness of the topsheet 2 is the average value of the thicknesses of three rectangular test pieces, each 8 cm long along the longitudinal direction X and 7 cm long along the transverse direction Y. The thickness is measured using a laser thickness meter (Omron Corporation's "ZSLD-80") with a load of 50 Pa applied to the test piece. If it is not possible to obtain a test piece of the above size because the area of ​​the nonwoven fabric to be measured is small, for example, a test piece with as large an area as possible is cut out.

[0107] [Example of size and arrangement of central compression section] The dimension of one central compressed portion 8 in the longitudinal direction X is preferably 1 mm or more, more preferably 2 mm or more, from the viewpoint of exerting the above-mentioned overflow suppression effect, and is preferably 20 mm or less, more preferably 15 mm or less, from the viewpoint of suppressing discomfort when worn due to the central compressed portion 8 being too large. The dimension of one central compressed portion 8 in the transverse direction Y is preferably 0.1 mm or more, more preferably 0.2 mm or more, from the viewpoint of exerting the above-mentioned overflow suppression effect, and is preferably 2 mm or less, more preferably 1.5 mm or less, from the viewpoint of suppressing discomfort when worn due to the central compressed portion 8 being too large.

[0108] The number of central compressing units 8 can be set appropriately depending on the size of each central compressing unit 8, etc., but is preferably 2 or more, more preferably 3 or more, and preferably 20 or less, more preferably 15 or less. The number of columns Ln of central compressing units 8 is, for example, preferably 2 or more, more preferably 3 or more, and preferably 10 or less, more preferably 8 or less. The number of central compressing units 8 belonging to one column Ln is, for example, preferably 2 or more, more preferably 3 or more, and preferably 10 or less, more preferably 8 or less.

[0109] The distance in the vertical direction X between adjacent central compressed portions 8 in the vertical direction X is preferably 2 mm or more, more preferably 3 mm or more, from the viewpoint of suppressing discomfort when worn, and is preferably 10 mm or less, more preferably 8 mm or less, from the viewpoint of effectively exerting the above-mentioned overflow suppression effect. The distance in the horizontal direction Y between adjacent vertical columns Ln in the horizontal direction Y is preferably 5 mm or more, more preferably 6 mm or more, from the viewpoint of suppressing discomfort when worn, and is preferably 30 mm or less, more preferably 25 mm or less, from the viewpoint of effectively exerting the above-mentioned overflow suppression effect.

[0110] [Other embodiments] 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.

[0111] In the above embodiment, an example was given in which the napkin 1 includes the intermediate sheet 5 between the topsheet 2 and the absorbent body 4, but the present invention is not limited to this, and the napkin 1 does not necessarily need to include the intermediate sheet 5.

[0112] In the above embodiment, the topsheet 2 has the strip-shaped portion 11 and the spacing portion 12, but is not limited to this configuration.

[0113] In the above embodiment, a sanitary napkin is shown as an example of the absorbent article, but the absorbent article of the present invention is not limited to this. For example, the absorbent article of the present invention may be a pad-type absorbent article other than a sanitary napkin, such as a urine absorption pad or a panty liner, or a disposable diaper. [Example]

[0114] [Manufacture of absorbent articles] Example 1 Unabsorbent cotton was prepared as the first cellulose fiber, and absorbent cotton was prepared as the second cellulose fiber, and a web was produced by mixing these. The first contact angle of the first cellulose fiber was 61.2°, and the second contact angle of the second cellulose fiber was 38.5°. By treating these with a fiber treatment agent, the first contact angle was adjusted to 72.6° and the second contact angle to 49.8°. The mass ratio P / Q of the content P of the first cellulose fiber to the content Q of the second cellulose fiber was 25 / 75 (= 1 / 3). This web was placed on a support and subjected to a water jet treatment (spunlace treatment) to produce a spunlace nonwoven fabric having a low basis weight portion including a fiber portion and a void portion. Furthermore, this nonwoven fabric (surface sheet) and an air-through nonwoven fabric (basis weight: 25 g / mm) made of thermoplastic fiber were mixed. 2 A cotton swab (1.8 mm thick, fineness: 2.4 dtex, thickness: 1.8 mm) was laminated with an absorbent body and a backsheet (same specifications as Kao Corporation's "Happy Skin Botanical Cotton 22.5 cm with wings") and bonded to each other with a hot melt adhesive. Furthermore, a central compressed section was formed on the topsheet side of this laminate by compression processing so as to overlap with the low basis weight section. Thus, the napkin of Example 1 was produced (see Table 1).

[0115] Example 2 The napkin of Example 2 was produced in the same manner as in Example 1, except that the mass ratio P / Q of the content P of the first cellulose fibers to the content Q of the second cellulose fibers was changed to 50 / 50 (=1) (see Table 1).

[0116] (Comparative Example 1) A napkin of Comparative Example 1 was produced in the same manner as in Example 1, except that the mass ratio P / Q of the content P of the first cellulose fibers to the content Q of the second cellulose fibers was changed to 0 / 100 (consisting only of the second cellulose fibers) (see Table 1). In other words, the topsheet of Comparative Example 1 was formed only of the second cellulose fibers. In Comparative Example 1, the topsheet had a low basis weight portion.

[0117] (Comparative Example 2) A napkin of Comparative Example 2 was produced in the same manner as in Example 1, except that the mass ratio P / Q of the content P of the first cellulose fibers to the content Q of the second cellulose fibers was changed to 100 / 0 (see Table 1). That is, the topsheet of Comparative Example 2 was formed only from the first cellulose fibers. In Comparative Example 2, the topsheet had a low basis weight portion.

[0118] (Comparative Example 3) A napkin of Comparative Example 3 was produced in the same manner as in Example 1, except that the low basis weight portion was not formed (see Table 1).

[0119] Comparative Example 4 A napkin of Comparative Example 4 was produced in the same manner as in Example 1, except that the central compressed section was not formed (see Table 1). In this example, a low basis weight section was formed, but did not contain a fibrous section.

[0120] [Table 1]

[0121] [Preparation of artificial blood] Sterile defibrated equine blood (Japan Biomaterials Center Co., Ltd.) (hereafter referred to as "horse blood") was prepared. Plasma and blood cell components were separated into upper and lower portions in a reagent bottle and mixed in appropriate amounts at room temperature to prepare simulated blood samples of 8 cp ± 0.1 cp (hereafter referred to as "8 cp") and 24 cp ± 0.1 cp (hereafter referred to as "24 cp"). Viscosity was measured using a VISCOMETER TVB-10 (Tohki Sangyo Co., Ltd.) at 25°C, rotor No. 19, and 30 rpm for 60 seconds.

[0122] [Evaluation of the amount of liquid returning] A cylindrical acrylic plate for evaluation was placed in the horizontal center of the intermediate region of the prepared napkin, and 3 g of the above-mentioned artificial blood adjusted to 8 cp was poured into it. The time from the moment of pouring until the liquid level disappeared was measured, and the napkin was left to stand for 1 minute from the moment the liquid level disappeared. After 1 minute had passed, tissue paper (folded in three, 100 mm x 50 mm square, Kleenex (trade name) manufactured by Nippon Paper Crecia Co., Ltd.) was placed on the napkin and 5 g / cm 2 The tissue was allowed to rest for 2 minutes from the moment the tissue was removed, and then 3 g of simulated blood was injected again. The above procedure was repeated once more, and the amount of liquid returned was measured after a total of 6 g of simulated blood had been injected. The above measurement of the amount of liquid returned was performed three times for each type of sample, and the average of the three measurements was calculated as the amount of liquid returned for each sample. The results for each sample are shown in Table 1.

[0123] As shown in Table 1, the amounts of liquid wetback in Examples 1 and 2 and Comparative Examples 2 and 3 were less than those in Comparative Examples 1 and 4, and were therefore favorable. The sample of Comparative Example 1, which had a topsheet composed only of the second cellulose fibers, had a significantly greater amount of liquid wetback than the sample of Comparative Example 2, which had a topsheet composed only of the first cellulose fibers, demonstrating that the amount of liquid wetback in the topsheet is improved by using first cellulose fibers that are primarily made of unabsorbed cotton. Comparing Example 1 and Example 2, Example 2, which had a large mass ratio P / Q and a high content of the first cellulose fibers, had a lower amount of liquid wetback, resulting in favorable results. The sample of Comparative Example 4, which did not have a central compression section, had a greater amount of liquid wetback than the samples of Examples 1 and 2, which did have a central compression section.

[0124] Evaluate overflow values Using a tube connected to a micropump, 1.5 g of the above-mentioned simulated blood, adjusted to 24 cp, was dropped over 10 seconds onto the horizontal center of the mid-region of the prepared napkin. The tip of the tube was in contact with the top sheet of the napkin when the drop was dropped. The farthest distance the simulated blood spread from the drop position on the skin-facing surface of the top sheet was measured using a ruler. The average of three measurements for each sample was calculated as the overflow value. The results for each sample are shown in Table 1.

[0125] As shown in Table 1, the overflow values ​​of Examples 1 and 2 were smaller than the overflow values ​​of Comparative Examples 2 to 4, and it was found that the overflow phenomenon was suppressed.

[0126] [Summary] From the above, it was found that the napkins of Examples 1 and 2 of the present invention, which contain a mixture of the first cellulose fiber and the second cellulose fiber and have a top sheet having a configuration in which a central compressed section and a low basis weight section overlap, can effectively suppress both liquid return and overflow on the top sheet. [Explanation of symbols]

[0127] 1... Napkins (absorbent articles) 2...Surface sheet 21…Low basis weight part 3...Back sheet 4...Absorbent 5...Middle seat 8...Central compression section 9...Outer compression section

Claims

1. An absorbent article comprising a top sheet, a back sheet, and an absorbent body disposed between the top sheet and the back sheet, and having a vertical direction corresponding to the front-to-back direction of a wearer, a horizontal direction corresponding to the left-to-right direction of the wearer and perpendicular to the vertical direction, and a thickness direction perpendicular to the vertical direction and the horizontal direction, In the longitudinal direction, the cushion is divided into a middle region including an excretory part facing region facing the excretory part of the wearer, a front region located in front of the middle region in the longitudinal direction, and a rear region located behind the middle region in the longitudinal direction, the top sheet includes first cellulose fibers and second cellulose fibers that are more hydrophilic than the first cellulose fibers, and is made of a nonwoven fabric in which the first cellulose fibers and the second cellulose fibers are mixed; the topsheet has a plurality of low basis weight portions having a basis weight lower than that of surrounding areas, the plurality of low basis weight portions are arranged spaced apart from one another at least in the intermediate region, The absorbent article further comprises: a central compressed portion recessed in the thickness direction from the topsheet to the absorbent body and extending in the longitudinal direction; The central compression section is disposed in a horizontally central section, which is a central section obtained by dividing the intermediate section into three equal parts in the horizontal direction, the central compressed portion is disposed so as to overlap the low basis weight portion in a plan view seen from the thickness direction. Absorbent articles.

2. The absorbent article includes a plurality of central compressed portions, The plurality of central compression portions are spaced apart from one another. The absorbent article of claim 1.

3. the central compressed portion is disposed so as to overlap two or more of the low basis weight portions in the plan view; The absorbent article of claim 1.

4. The low basis weight portion is a fiber portion including the first cellulose fibers and the second cellulose fibers; and a void portion not containing fibers, In the fiber portion, the first cellulose fibers and the second cellulose fibers are entangled. The absorbent article according to any one of claims 1 to 3.

5. The absorbent article comprises: The absorbent article further includes an intermediate sheet that is mainly composed of thermoplastic fibers and is disposed between the top sheet and the absorbent body. In the low basis weight section that is arranged to overlap the central compressed section, at least one of the first cellulose fibers or the second cellulose fibers of the fibrous section is in contact with the thermoplastic fibers of the intermediate sheet. The absorbent article of claim 4.

6. the first cellulose fibers are mainly composed of undefatted fibers, The second cellulose fibers are mainly composed of defatted fibers. The absorbent article according to any one of claims 1 to 3.

7. a first contact angle, which is a contact angle between the first cellulose fibers and water, of 89° or less; a second contact angle, which is a contact angle between the second cellulose fibers and water, is 60° or less and is smaller than the first contact angle; The absorbent article according to any one of claims 1 to 3.

8. a first contact angle between the first cellulose fibers and water is 60° or more; a second contact angle, which is a contact angle between the second cellulose fibers and water, is 20° or more and smaller than the first contact angle; The absorbent article according to any one of claims 1 to 3.

9. In the topsheet, a mass ratio P / Q, which is a ratio of a content P of the first cellulose fibers to a content Q of the second cellulose fibers, is 1 / 9 or more and 1 or less. The absorbent article according to any one of claims 1 to 3.

10. The absorbent article comprises: Further provided is an outer compressed portion recessed in the thickness direction from the topsheet to the absorbent body and extending in the longitudinal direction, The outer compression section is disposed laterally outward of the central compression section and has a larger dimension in the vertical direction than the central compression section. The absorbent article according to any one of claims 1 to 3.

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