absorbent articles

Abstract

To provide an absorbent article that offers an improved fit to the buttocks and prevents any leakage along the same.SOLUTION: An absorbent article has an elongated body comprising a skin-side top sheet, a non-skin-side back sheet on a side opposite from the skin side, and an absorber that is disposed between the top sheet and the back sheet, wherein the body has a low-density region that extends over a longitudinal center line extending along the longitudinal direction of the absorbent article and also extends in a lateral direction in a rearward portion of a buttocks-facing area that faces the buttocks of a wearer when worn, and a whole area of the low-density region is surrounded by a high-density region having higher density than the low-density region.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] As absorbent articles such as sanitary napkins, products for long-term use or overnight use, which have a long rear region so that the main body faces the buttocks, are known. For such absorbent articles, various designs have been studied to prevent leakage of bodily fluids from the rear region. These designs include improvements in the shape of the absorbent core.

[0003] For example, Patent Document 1 describes an absorbent article having an absorbent core (absorbent body) that is elongated in the front-to-rear direction, in which the central region of the absorbent core has a protrusion that protrudes upward from the upper surface of the side region, and the protrusion is formed from a portion facing the excretory part that is positioned opposite the wearer's excretory part to a rear portion that is positioned behind the excretory part facing the excretory part. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-104094 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the above-described conventional configurations, when an absorbent article is used at night or for a long period of time, there is still a concern that the absorbent body facing the intergluteal cleft may not be able to absorb all of the body fluids, and the body fluids may leak along the intergluteal cleft to the rear or rear-lateral side of the intergluteal cleft, depending on the manner in which the article is worn, the wearer's movements while wearing the article, etc. Therefore, there is a need to improve the fit to the buttocks, particularly the fit to the area behind the intergluteal cleft or the area further behind the rear end of the intergluteal cleft, to prevent the leakage of body fluids along the fit.

[0006] In view of the above, an object of one aspect of the present invention is to provide an absorbent article that can improve the fit to the buttocks and prevent leakage. [Means for solving the problem]

[0007] A first aspect of the present invention is an absorbent article having an elongated main body comprising a skin-facing top sheet, a non-skin-facing back sheet opposite the skin-facing side, and an absorbent body arranged between the top sheet and the back sheet, wherein the main body has a low-density region at the rear of a buttocks-facing region that faces the wearer's buttocks when worn, the low-density region spanning a longitudinal center line extending along the longitudinal direction of the absorbent article and extending laterally, and the low-density region is entirely surrounded by a high-density region that is denser than the low-density region.

[0008] According to the first aspect, the low-density region is formed in the rear of the buttocks-facing region, so that when worn, the low-density region can be positioned facing a region near the rear of the wearer's intergluteal cleft or a region behind the rear end of the intergluteal cleft. Because the low-density region is highly flexible, it can fit closely to the shallow depression in the rear of the intergluteal cleft or along a skin surface with almost no depression, improving the fit of the main body. Furthermore, when bodily fluid migrates rearward along the intergluteal cleft toward the low-density region, it is difficult for the bodily fluid to diffuse from the high-density region to the low-density region, so the diffusion rate decreases before the low-density region. Furthermore, bodily fluid that enters the low-density region diffuses relatively slowly in the rear and lateral directions, allowing the absorbent body to be utilized laterally as well. Furthermore, the low-density region has many gaps between the pulp, allowing it to retain a relatively large amount of bodily fluid. In this way, the low-density region acts as a stopper, so to speak, to prevent leakage.

[0009] In a second aspect of the present invention, the densified region is a region densified by compression.

[0010] According to the second aspect, the high-density region is formed by a relatively simple method called compression, which prevents the manufacturing process from becoming complicated. By preparing compression molds corresponding to the low-density region and the high-density region, it is possible to densify the desired region using an absorbent body with a uniform basis weight, thereby obtaining a low-density region without densifying the desired region. Furthermore, the formation of a high-density region in the absorbent body improves the shape retention of the absorbent body and prevents unintended unraveling of the absorbent body.

[0011] In a third aspect of the present invention, the buttocks-facing region includes a uniform-basis-weight region in which the pulp basis weight of the absorbent body is substantially uniform, and the low-density region is partially formed within the uniform-basis-weight region.

[0012] According to the third aspect of the present invention, since the pulp basis weight is uniform in the low-density region and the high-density region, the thickness of the low-density region can be increased. Furthermore, there is no need to adjust the local density of the low-density region during fiber stacking of the absorbent body, which prevents the manufacturing process from becoming complicated.

[0013] In a fourth aspect of the present invention, the low-density region has a shape that is convex backward.

[0014] According to the fourth aspect of the present invention, the low-density region can be fitted to surround the posterior end of the intergluteal cleft from the rear, thereby more reliably preventing leakage even if bodily fluids travel in a direction slightly deviating from the longitudinal direction.

[0015] In a fifth aspect of the present invention, compressed grooves recessed from the top sheet side are formed in at least the top sheet and the absorbent body, and the compressed grooves include a first compressed groove extending laterally in front of the low-density region and a second compressed groove extending laterally behind the low-density region.

[0016] According to the fifth aspect, when the rear region of the buttocks-facing region is bent in the longitudinal direction during wear, the highly flexible low-density region receives compressive force from the first and second compressed grooves and can deform so as to bulge toward the top sheet. This improves the fit of the main body to areas with a shallow or no intergluteal cleft. Furthermore, because the first and second compressed grooves extend laterally, they also act to block bodily fluids that migrate rearward.

[0017] In a sixth aspect of the present invention, the first compressed groove and the second compressed groove each have a shape that includes a shape that is convex backward.

[0018] According to the sixth aspect, the first compressed groove (first rear compressed groove) and the second compressed groove (second rear compressed groove) can also prevent bodily fluids from migrating diagonally rearward or laterally. Furthermore, when the rear of the buttocks-facing region is to be aligned along the entire buttocks, the main body needs to be curved three-dimensionally in both the longitudinal and lateral directions, but the shapes of the first compressed groove and second compressed groove according to this aspect allow the three-dimensional curvature to be formed naturally. [Effects of the Invention]

[0019] According to one aspect of the present invention, an absorbent article can be provided that can improve the fit around the buttocks and prevent leakage. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a plan view of an absorbent article according to one embodiment of the present invention, viewed from the top sheet side. [Figure 2] This is a cross section taken along line II in Figure 1. [Figure 3] FIG. 2 is a plan view of the absorbent article of FIG. 1 with the absorbent body exposed. [Figure 4] FIG. 2 is a partially enlarged view of FIG. [Figure 5] 5 is a diagram showing a part of a cross section of the absorber taken along line II-II in FIG. 4. FIG. [Figure 6] 10A and 10B are diagrams for explaining the formation of high density regions and low density regions. [Figure 7] FIG. 2 is an enlarged plan view of a high-density region. [Figure 8] FIG. 4 is a diagram similar to FIG. 3, but is used to explain the basis weight of the absorbent body. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, unless otherwise specified, the same or corresponding components will be denoted by the same reference numerals and the description thereof will be omitted.

[0022] <Basic structure of absorbent articles> First, the basic structure of an absorbent article will be explained using an overnight or long-lasting sanitary napkin as an example. Fig. 1 shows a plan view of an absorbent article 1. Fig. 2 shows a cross-sectional view taken along line II in Fig. 1.

[0023] As shown in Figures 1 and 2, the absorbent article 1 comprises a liquid-permeable top sheet 3 arranged on the side that faces the wearer's skin when worn, i.e., the skin side, and a liquid-impermeable back sheet 2 arranged on the non-skin side (underwear side) opposite the skin side. Furthermore, an absorbent body (absorbent core) 4 is arranged between the back sheet 2 and the top sheet 3. The back sheet 2, absorbent body 4, and top sheet 3 are layered to form a main body (absorbent article main body) 8. The absorbent body 4 is arranged so as not to protrude from the back sheet 2 and top sheet 3 in a plan view. At both end edges in the longitudinal direction D1, the edges of the back sheet 2 and the top sheet 3 may be joined by adhesive, heat sealing, or the like.

[0024] As shown in the figure, the absorbent article 1 is in the shape of an elongated pad (a shape in which the thickness is smaller than the width and length). In this specification, the longitudinal direction (front-to-back direction) of the absorbent article 1 is designated D1, and the lateral direction (left-to-right or width direction) perpendicular to the longitudinal direction D1 is designated D2. The longitudinal direction D1 corresponds to the front-to-back direction of the wearer's body when the absorbent article 1 is worn, and the lateral direction D2 corresponds to the left-to-right direction of the body.

[0025] 1 and 2, the main body 8 has a shape in plan view that is approximately line-symmetrical with respect to a center line (longitudinal center line) CL extending in the longitudinal direction D1, but the shape of the main body 8 does not necessarily have to be line-symmetrical. Furthermore, configurations other than the shapes of the absorbent article 1 and the main body 8 (including the thickness and density of the absorbent body 4, the size and position of the compressed grooves, the shape and size of the flaps extending outward from the main body 8 in the lateral direction D2, etc.) may be approximately symmetrical or asymmetrical with respect to the center line CL as the axis of symmetry.

[0026] The backsheet 2 may be a sheet that is at least water-proof, for example, a sheet made of an olefin resin such as polyethylene or polypropylene. Alternatively, a laminated nonwoven fabric in which a nonwoven fabric is laminated on a polyethylene sheet or the like, or a laminated sheet of nonwoven fabric in which a waterproof film is interposed to ensure substantial liquid impermeability, may be used. Furthermore, it is more desirable to use a material that is moisture-permeable in order to prevent stuffiness. Examples of such water-proof and moisture-permeable sheet materials include microporous sheets obtained by melt-kneading an inorganic filler in an olefin resin such as polyethylene or polypropylene to form a sheet, and then stretching the sheet uniaxially or biaxially. The backsheet 2 may be a sheet having the same outer shape as the outer shape of the absorbent article 1.

[0027] The top sheet 3 can be a liquid-permeable sheet that allows bodily fluids such as menstrual blood, vaginal discharge, and urine to quickly pass through. Suitable top sheet 3 materials include perforated or non-perforated nonwoven fabrics and porous plastic sheets. Examples of material fibers constituting the nonwoven fabric include olefins such as polyethylene and polypropylene, synthetic fibers such as polyester and polyamide, regenerated fibers such as rayon and cupra, and blends thereof, as well as natural fibers such as cotton, which can be used alone or in combination. Examples of processing methods for nonwoven fabrics include spunlace, spunbond, thermal bond, meltblown, and needlepunch. Of these processing methods, the spunlace method is preferred because it provides flexibility, the spunbond method is preferred because it can produce nonwoven fabrics with excellent drapeability, and the thermal bond method is preferred because it can produce bulky and soft nonwoven fabrics. Composite fibers, such as core-sheath fibers, side-by-side fibers, and splittable fibers, can also be used, each of which has a high-melting-point fiber as the core and a low-melting-point fiber as the sheath.

[0028] The absorbent body 4 is not limited to any material that can absorb and retain body fluids, but preferably contains cotton-like pulp and a water-absorbent polymer. Examples of water-absorbent polymers that can be used include superabsorbent polymer (SAP), superabsorbent fiber (SAF), and combinations of these. Pulp includes chemical pulp obtained from wood, cellulose fibers such as dissolving pulp, and artificial cellulose fibers such as rayon and acetate. Hardwoods and softwoods are used as raw materials for chemical pulp, with softwoods being preferred due to their long fiber length.

[0029] Synthetic fibers may be blended into the absorbent body 4. Examples of synthetic fibers that can be used include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon, and copolymers thereof. Two of these fibers can also be blended. Composite fibers, such as core-sheath fibers with a high-melting-point fiber as the core and a low-melting-point fiber as the sheath, side-by-side fibers, and splittable fibers, can also be used. Hydrophobic fibers can also be surface-treated with a hydrophilizing agent to impart affinity to body fluids. The absorbent body 4 is preferably manufactured by stacking or air-laid methods.

[0030] The absorbent body 4 may have compressed absorbent body parts (including high-compression absorbent body parts and low-compression absorbent body parts) formed in parts that are recessed from the top sheet 3 side to the back sheet 2 side (described in detail later). Furthermore, the absorbent body 4 may be wrapped in an envelope sheet made of colored or uncolored (white) crepe paper, nonwoven fabric, or the like to prevent kinking, cracking, or spillage of polymer particles.

[0031] Side sheets 7, 7 are arranged on both sides of the absorbent article 1, i.e., on the side in the lateral direction D2, along the longitudinal direction D1, facing the skin. The side sheets 7 may be made of a material that has been treated, entirely or partially, with an appropriate water-repellent or hydrophilic treatment, depending on the purpose, such as preventing penetration of bodily fluids or improving the feel against the skin. The side sheets 7 are preferably nonwoven fabrics containing natural fibers, synthetic fibers, recycled fibers, etc., or made from these fibers. When the side sheets 7 are nonwoven fabrics, they may be air-through nonwoven fabrics, spunlace nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, etc., but air-through nonwoven fabrics are preferred because they are resistant to creases, wrinkles, and soft, improving the feel against the skin. The side sheets 7 may also be treated with a water-repellent agent, such as a silicone-based or paraffin-based water-repellent agent.

[0032] The side sheet 7 may be folded back on the inside in the lateral direction D2 to form a multi-layered band-like portion extending along the side of the main body 8. Gathers may be formed by disposing an elastically stretchable member in a stretched state between the multiple layers along the longitudinal direction D1. In this specification, the configuration of the folds and gathers of the side sheet 7 will not be described, and will not be shown in the drawings.

[0033] The absorbent article 1 may have a body fluid discharge outlet-facing region C that faces the wearer's body fluid discharge outlet (the vaginal opening in the illustrated example) when worn, a front region F that is adjacent to the front of the body fluid discharge outlet-facing region C and extends to the front end of the absorbent article 1, a perineum-facing region (middle region) M that is adjacent to the rear of the body fluid discharge outlet-facing region C and faces the vicinity of the wearer's perineum when worn, and a buttocks-facing region B that is adjacent to the rear of the perineum-facing region M and extends to the rear end of the absorbent article 1 and faces the wearer's buttocks when worn. The perineum-facing region M and buttocks-facing region B may be collectively referred to as the rear region. The buttocks-facing region B includes a front buttocks-facing region B1 that is adjacent to the perineum-facing region M and a rear buttocks-facing region B2 that is adjacent to the rear of the front buttocks-facing region B1. The front buttocks-facing region B1 is a region that primarily faces the intergluteal cleft (gluteal groove) and faces the area including the anus. The rear buttocks-facing region B2 may be a region that faces the rear part of the intergluteal cleft of the buttocks or a region further rearward from near the rear end of the intergluteal cleft, particularly a region rearward (above when standing) of the intergluteal groove, which can be said to be the boundary between the buttocks and the legs. Note that the above description of the facing relationship between the regions of the main body 8 and the wearer's body is a rough range when the wearer wears the absorbent article in a normal manner while lying down, but is merely a guide.

[0034] The length in the longitudinal direction D1 of the bodily fluid outlet-facing region C may be 50 to 120 mm, and the length in the longitudinal direction D1 of the buttocks-facing region B may be 90 to 230 mm. Furthermore, the configuration of this embodiment is suitable for, for example, absorbent articles with a long rear, in which the total length of the perineum-facing region M and the buttocks-facing region B, preferably the length in the longitudinal direction D1 of the buttocks-facing region B, is longer than the length in the longitudinal direction D1 where the wing flaps WF are provided. Furthermore, the length in the longitudinal direction D1 of the front buttocks-facing region (gluteal cleft-facing region) B1 may be 40 to 100 mm, and the length in the longitudinal direction D1 of the rear buttocks-facing region B2 may be 40 to 120 mm. Furthermore, the total length in the longitudinal direction D1 of the absorbent article 1 may be 250 to 450 mm.

[0035] The absorbent article 1 may include a pair of wing flaps WF, WF extending outward in the lateral direction D2 from both sides of the region C facing the bodily fluid discharge opening. Anti-slip materials (not shown) may be provided on the non-skin sides of the wing flaps WF, WF, and this anti-slip material allows the wing flaps WF, WF to be folded back to the non-skin sides and attached to the underwear so that the underwear is sandwiched between the wing flaps WF, WF and the main body 8 when worn. This allows the absorbent article 1 to be securely fixed to the underwear. The wing flaps WF, WF are formed by joining the outward extending portions of the side sheets 7, 7 in the lateral direction D2 and the outward extending portion of the back sheet 2 in the lateral direction D2.

[0036] In addition, a pair of hip hold flaps HF, HF may be formed extending outward in the lateral direction D2 from the sides of the main body 8 from the perineum-facing region M to the buttocks-facing region B. The hip hold flaps HF, HF prevent leakage of bodily fluids at the rear of the absorbent article 1 and, by increasing the contact area with the buttocks, make it less likely that the entire absorbent article 1 will shift relative to the underwear, particularly in the lateral direction D2, thereby stabilizing the wearing position of the absorbent article 1. The hip hold flaps HF, HF may also be formed by joining the outward extensions in the lateral direction D2 of the side sheets 7, 7 and the outward extensions in the lateral direction D2 of the back sheet 2.

[0037] <Specific composition of the absorbent body> FIG. 3 shows a plan view of the absorbent article 1 of FIG. 1 with the top sheet 3 and side sheets 7, 7 removed to expose the absorbent body 4. As shown in FIGS. 1 and 3, the main body 8 has regions in the buttocks-facing region B where the density of the absorbent body 4 varies locally. More specifically, the absorbent body 4 has a low-density region 46 and a high-density region 45 that surrounds the low-density region 46 and has a higher density, preferably a higher pulp density, than the low-density region 46. In this specification, the terms low density and high density refer to relative densities and do not indicate a specific density. However, the pulp density of the low-density region 46 may be 40 to 90%, preferably 60 to 80%, of the pulp density of the high-density region 45. The pulp density of the low-density region 46 is preferably 0.035 to 0.1 g / cm. 3 , more preferably 0.05 to 0.08 g / cm 3 The pulp density of the high density region 45 is preferably 0.055 to 0.15 g / cm 3 , more preferably 0.07 to 0.12 g / cm 3 It may be.

[0038] The low-density region 46 is provided mainly in the rear buttock-facing region B2, and is formed in a region facing the rear portion of the wearer's buttocks when worn, or a region closer to the upper body than the gluteal crease when the wearer is in a supine position. As shown in Figures 1 and 3, the low-density region 46 is formed to straddle the longitudinal centerline CL and extend in the lateral direction D2. When worn, the low-density region 46 faces a shallow depression near the rear end of the wearer's intergluteal cleft or a substantially flat skin surface posterior to the rear end of the intergluteal cleft. Due to its flexibility, the low-density region 46 can deform to fit the shape of the skin surface and adhere closely to the skin, providing a comfortable fit.

[0039] A low-density region 46' having a lower density than the surrounding area may also be formed in front of the low-density region 46, from the bodily fluid outlet facing region C to the perineum facing region M. This front low-density region 46' may be formed to include a high-basis-weight portion 4H (described in detail later) having a relatively high pulp basis weight. In this embodiment, as shown in FIG. 3, the region other than the low-density regions 46, 46' is a high-density region 45.

[0040] FIG. 4 shows an enlarged view of the low-density region 46 of the absorbent body 4 in FIG. 1 and the surrounding region. When body fluid migrates backward along the longitudinal centerline CL through the intergluteal cleft during wear, it will migrate from the high-density region 45 into the low-density region 46 (as shown by the white arrow in FIG. 4). Generally, fluid does not easily diffuse from a high-density absorbent body to a low-density absorbent body, so the diffusion rate temporarily slows down at the front edge of the low-density region 46, and the subsequent diffusion within the low-density region 46 also does not proceed rapidly backward, but rather proceeds relatively slowly and in the lateral direction D2 (white arrow in FIG. 4). Therefore, the absorbent body 4 can be utilized across the lateral direction D2. Furthermore, since the low-density region 46 has many gaps between the pulp contained in the absorbent body 4, it has a large capacity for holding bodily fluids and is less likely to migrate rearward. Therefore, the low-density region 46 acts as a stopper, so to speak, and can prevent bodily fluids from migrating further rearward, thereby preventing leakage. Furthermore, it can also block bodily fluids that have not traveled down the intergluteal cleft but have not been absorbed in the region C opposite the bodily fluid outlet and have migrated rearward within the absorbent body 4.

[0041] The method for forming the regions with different densities (low-density region 46 and high-density region 45) is not particularly limited, but it is preferable to form them by squeezing (or compressing) in the thickness direction a fiber stack prior to becoming the absorbent body 4. In this case, the high-density region 45 is a region that has been densified by squeezing, and the low-density region 46 is a region that has not been substantially squeezed (or compressed). "Substantially not squeezed (or compressed)" means that no pressure in the thickness direction is applied from a squeezing mold (also called a core embossing mold, described in detail later) during the squeezing process to form the high-density region 45. However, the low-density region 46 may have a squeezed portion as long as the function of the low-density region 46 in this embodiment is not impaired.

[0042] The low-density region 46 as a whole has a shape that straddles the longitudinal centerline CL and extends in the lateral direction D2, but may also be curved in a shape that convexes backward. In the illustrated example, the low-density region 46 has a cashew-nut shape (a curved band shape with rounded ends, or an ellipse with the center of the major axis of the ellipse curved toward one side of the major axis). Because the low-density region 46 has such a convex shape backward, it can envelop and block bodily fluid that migrates backward near the center in the lateral direction D2, thereby effectively blocking bodily fluid that deviates from the longitudinal direction D1. Furthermore, the convex shape backward allows the low-density region 46 and its surrounding area to naturally deform along the curvature of the buttocks.

[0043] The radius of curvature of the center line L of the low-density region 46 (a curved center line roughly along the transverse direction D2) may be 13 to 35 mm, and may be 15 to 25 mm at least along the longitudinal center line CL. The degree of curvature of the low-density region 46 can improve the aforementioned effects, such as good retention of bodily fluids and natural deformation. The width (length in the transverse direction D2) a of the low-density region 46 may be 30 to 60 mm, and may be preferably 40% or more, more preferably 60% or more, of the length of the absorbent body 4 in the transverse direction D2. The length (length in the longitudinal direction D1) b of the low-density region 46 may be 10 to 30 mm. The ratio (a / b) of the length of the low-density region 46 in the transverse direction D2 to its length in the longitudinal direction D1 may be 1.5 to 4.

[0044] As shown in Figure 4, the high-density region 45 includes low-compression absorbent body portions 42 and high-compression absorbent body portions 41, 41, ... that are compressed to a deeper depth than the low-compression absorbent body portions 42. In the example shown, the high-compression absorbent body portions 41, 41, ... are arranged in a scattered manner. That is, a plurality of high-compression absorbent body portions 41, 41, ... are arranged at a distance from one another. In the high-density region 45, the areas other than the high-compression absorbent body portions 41, 41, ... are low-compression absorbent body portions 42. The formation of the high-compression absorbent body portions 41, 41, ... prevents the high-density region 45 from becoming too hard and ensures that the absorbent body 4 is compressed more reliably in the thickness direction, making it less likely to lose its shape or come undone even during use.

[0045] FIG. 5 shows a schematic cross section of a portion of the absorbent body 4 taken along line II-II in FIG. 4. As shown in FIG. 5, high-density regions 45, 45 are formed before and after the low-density region 46. The high-density regions 45, 45 are compressed in the thickness direction overall and are thinner than the low-density region 46. As shown in FIG. 5, the relatively raised low-density region 46 enhances its function as a leak stopper, deforming to conform to the shape of the skin and adhering closely to the skin. Furthermore, because the low-density region 46 is highly flexible, it is less likely to cause discomfort even when the wearer is lying supine. Furthermore, as shown in FIG. 5, the low-density region 46 is formed in the rear buttock-facing region B2, allowing it to better fit to body parts with shallow or no intergluteal clefts. Note that reference numerals 11' and 12' in FIG. 5 indicate the positions of compression grooves (also called fit embossing, described in detail below) formed in at least the top sheet 3 and the absorbent body 4 in a process subsequent to the absorbent body manufacturing process.

[0046] Here, with reference to FIG. 6, the formation of regions with different densities (high-density region 45 and low-density region 46) will be described. To form differences in density depending on the location, for example, as shown in FIG. 6(a), a compression mold 80 with an uneven surface is prepared, and this compression mold 80 is pressed against the surface of a stack 4a in which absorbent material has been stacked. The compression mold 80 is provided with recesses 86 corresponding to the low-density regions 46, and the regions within the recesses 86 are not compressed in the thickness direction. The surface surrounding the recesses 86 is a low-compression surface 82 corresponding to the absorbent low-compression section 42, and further, a plurality of high-compression protrusions 81, 81, ... corresponding to the absorbent high-compression section 41 are formed at intervals within the low-compression surface 82. When the compression mold 80 is pressed against the stack 4a, as shown in FIG. 6(b), the low-compression surface 82 compresses the stack 4a in the thickness direction, but the stacks 4a within the recesses 86 are not compressed. As a result, the height of the stacks 4a located within the recesses 86 remains higher than the surrounding area, and densification does not or hardly occurs. Furthermore, since the multiple spaced high-pressure compression projections 81, 81, ... protrude from the low-pressure compression surface 82 toward the stacks 4a, deep depressions are formed in the stacks 4a at positions facing the high-pressure compression projections 81, 81, .... Thereafter, as shown in Figure 6(c), when the compression mold 80 is removed, an absorbent body 4 (Figure 5) is obtained in which low-density regions 46 have been formed and are sandwiched between high-density regions 45, 45 in the longitudinal direction D1. Then, a configuration is obtained in which high-pressure compression portions 41, 41, ... of the absorbent body are scattered within low-pressure compression portions 42 of the absorbent body, forming the high-density regions 45.

[0047] FIG. 7 shows a partially enlarged view of the high-density region 45 in FIG. 4. As shown in FIG. 7, in the high-density region 45, multiple absorbent body highly compressed portions 41, 41, ... are arranged at a distance from one another. Areas without absorbent body highly compressed portions 41, 41, ... are continuously extending absorbent body low-compression portions 42. In the example shown in FIG. 7, when the longitudinal direction D1 of the absorbent article 1 is viewed as the up-down direction, the absorbent body highly compressed portions 41, 41, ... are arranged in a staggered pattern, but the absorbent body highly compressed portions 41, 41, ... may also be arranged in a different pattern, for example, a lattice pattern. However, in the case of a staggered pattern as shown, even when the absorbent article 1 is subjected to force from both legs in the lateral direction D2, stress is easily distributed in the longitudinal direction D1, and the absorbent body 4 can be raised toward the top sheet 3 without distortion. In a staggered pattern, the distance p between the center of one absorbent body highly compressed portion 41 and the center of the absorbent body highly compressed portion 41 adjacent to that absorbent body highly compressed portion 41 in the lateral direction D2 is 1 / 2. x may be 4 to 12 mm on average, and the distance p between the center of one compressed absorber portion 41 and the center of the compressed absorber portion 41 adjacent to the compressed absorber portion 41 in the longitudinal direction D1 y may be 4 to 12 mm on average.

[0048] The multiple absorbent body compressed portions 41 may have the same shape and size in a plan view, but the absorbent body compressed portions 41 may include absorbent body compressed portions having different shapes, for example, as shown in FIG. 7, two different shapes of first absorbent body compressed portions 41A and second absorbent body compressed portions 41B. In the example shown in FIG. 7, the first absorbent body compressed portions 41A are circular, and the second absorbent body compressed portions 41B are elongated. Rows of the first absorbent body compressed portions 41A are spaced apart in the longitudinal direction D1, and rows of the second absorbent body compressed portions 41B are spaced apart in the longitudinal direction D1, and are arranged alternately. More specifically, the contour 41Ar and bottom surface 41Ab of the first absorbent body compressed portion 41A are both circular. On the other hand, the contour 41Br of the second absorbent body compressed portion 41B is an elongated hexagon, and the shape of the bottom 41Bb of the second absorbent body compressed portion 41B is elliptical. The contour shape and bottom shape of the absorbent body compressed portions 41, 41, ... can be adjusted, for example, by changing the shape of the compression projections 81 (Figure 6) of the compression mold 80 used when forming the absorbent body compressed portions 41, 41, ...

[0049] 7, the direction of the center line of the elongated second absorber compressed portion 41B (for example, the long axis direction if it is elliptical) may form an angle of 75° to 105°, preferably 90°, with the direction of the center line of an adjacent second absorber compressed portion 41B of the same shape in the lateral direction D2. This makes it difficult for stress to concentrate and distortion to occur within the absorber 4 even if the main body 8 is deformed such that the right side is pulled forward and the left side is pulled backward.

[0050] The absorbent body 4 does not have to have a uniform basis weight over the entire surface, and may have areas where the basis weight is locally increased or locally decreased. As mentioned above, the absorbent body 4 contains pulp and a water-absorbent polymer, and it is preferable that the basis weight of the water-absorbent polymer is approximately the same throughout the absorbent body 4. In this case, the relative magnitudes of the pulp basis weights are reflected in the relative magnitudes of the basis weights.

[0051] In order to explain the distribution of the basis weight of the absorbent body 4, Fig. 8 is a plan view clearly showing different basis weights within the absorbent body 4, with the absorbent body highly compressed portions 41, 41, ... in Fig. 3 omitted. As shown in Fig. 8, in the absorbent body 4, in the bodily fluid discharge outlet facing region C, a high basis weight portion 4H with a high basis weight may be formed in the center of the absorbent body 4 in the lateral direction D2. Furthermore, the continuous region in the center of the perineum facing region M and the front buttocks facing region B1 in the lateral direction D2 may be a low basis weight portion 4L with a low basis weight. In the example shown, the regions other than the high basis weight portion 4H and the low basis weight portion 4L are medium basis weight portions 4M with a basis weight lower than the high basis weight portion 4H and a basis weight higher than the low basis weight portion 4L. The medium weight portion 4M may extend to the front region F, the region surrounding the high weight portion 4H in the bodily fluid outlet facing region C, the region surrounding the low weight portion 4L in the front buttocks facing region B1, and the rear buttocks facing region B2. The high weight portion 4H, the medium weight portion 4M, and the low weight portion 4L may be uniform weight regions in which the weight is almost uniform within each portion. "Almost uniform weight within a specified portion or region" means that even if there are some portions where the weight varies slightly, the difference from the average weight within the specified portion or region is 20% or less of the average weight, preferably 10% or less, and more preferably 5% or less.

[0052] The low-density region 46 is formed in the rear buttocks-facing region B2. The rear buttocks-facing region B2 is a medium-basis-weight portion 4M, and may be a uniform-basis-weight region. That is, the low-density region 46 and the surrounding high-density region 45 have the same pulp basis weight. The pulp basis weight of the rear buttocks-facing region B2, which has a uniform pulp basis weight, is preferably 250 to 600 g / m 2 , more preferably 300 to 600 g / m 2 , and more preferably 400 to 500 g / m 2 It may be.

[0053] Since the low-density regions 46 and the high-density regions 45 have a uniform basis weight, the density of the low-density regions 46 can be reduced by compression, such as by forming the above-mentioned absorbent body compressed portions 41, 41, ..., and does not need to be reduced when stacking the absorbent body 4. Furthermore, according to this embodiment, the thickness of the low-density regions 46 is greater than the thickness of the high-density regions 45. In the absorbent body 4, the thickness of the low-density regions 46 may be 40 to 90% of the thickness of the high-density regions 45. Furthermore, the thickness of the low-density regions 46 of the absorbent body 4 may be 5 to 9 mm, and the thickness of the high-density regions of the absorbent body 4 may be 3 to 7 mm.

[0054] <Compression groove> As shown in FIGS. 1 and 2 , the main body 8 of the absorbent article 1 of this embodiment may have compressed grooves (fit embossments) formed by compressing at least the top sheet 3 and the absorbent body 4 from the top sheet 3 side. The compressed grooves have the function of absorbing and retaining bodily fluids, and can contribute to preventing the diffusion of bodily fluids or guiding them. In the illustrated example, the compressed grooves may include multiple compressed grooves (denoted by reference numerals 10, 11, 12, and 13). In a plan view, the compressed grooves may be formed in line symmetry with respect to the longitudinal centerline CL of the absorbent article 1, but line symmetry is not necessary. The compressed grooves can be formed, for example, by passing a laminate formed by stacking at least the top sheet 3 and the absorbent body 4 between a pair of pressure rolls. In this case, the laminate can be pressed by sandwiching it between the two rolls, with a convex roll positioned on the top sheet 3 side and a flat roll positioned on the absorbent body 4 side. The compression groove may include a low-compression section and a high-compression section compressed at a higher pressure within the low-compression section. In the drawings, the high-compression section is shown in black.

[0055] In the embodiment shown in FIG. 1, a pair of central compressed grooves 10, 10 extend along the longitudinal direction D1, primarily from the bodily fluid outlet-facing region C to the perineum-facing region M. The pair of central compressed grooves 10, 10 are formed spaced apart from each other on both sides of the longitudinal centerline CL. The pair of central compressed grooves 10, 10 are positioned so as not to overlap with the high basis weight portion 4H. The distance between the pair of central compressed grooves 10, 10 in the lateral direction D2 may be constant or may vary. For example, as shown in FIG. 1, the distance may be small near the boundary between the bodily fluid outlet-facing region C and the perineum-facing region M, large again behind that, and gradually small toward the rear end.

[0056] A first rear compressed groove (first compressed groove) 11 is formed behind the pair of central compressed grooves 10, 10 and spaced apart from the pair of central compressed grooves 10, 10. The first rear compressed groove 11 is formed in the buttocks-facing region B, mainly in the intergluteal cleft-facing region B1. The first rear compressed groove 11 has a shape that is convex rearward as a whole. More specifically, the first rear compressed groove 11 may include at least three arc-shaped portions that are convex rearward. Alternatively, the first rear compressed groove 11 may have a shape that includes a U-shaped, preferably horseshoe-shaped, compressed groove that overlaps with the longitudinal centerline CL and a compressed groove that branches off from the side of the U-shaped compressed groove and extends forward. Furthermore, a second rear compressed groove (second compressed groove) 12 is formed behind the first rear compressed groove 11 and spaced apart from the first rear compressed groove 11. The second rear compressed groove 12 is a groove that extends along the lateral direction D2 and has a rearwardly convex shape. In addition, a front compressed groove 13 is formed in front of the pair of central compressed grooves 10, 10. In the example shown in Figure 1, the front compressed groove 13 has a closed shape formed by combining compressed grooves that are curved forwardly and convexly with different radii of curvature.

[0057] As shown in Figures 3 and 4, it is preferable that the first rear compressed groove 11 is formed in front of the above-mentioned low-density region 46, and the second rear compressed groove 12 is formed behind the low-density region 46. Therefore, in a plan view, the low-density region 46 is sandwiched between the first rear compressed groove 11 and the second rear compressed groove 12. From the viewpoint of ensuring the flexibility of the low-density region 46, it is preferable that the first rear compressed groove 11 and the second rear compressed groove 12 do not overlap the low-density region 46, as shown in Figures 3 and 4. The formation positions of the first rear compressed groove 11 and the second rear compressed groove 12 are also shown in Figure 5 as planned formation position 11' of the first rear compressed groove 11 and planned formation position 12' of the second rear compressed groove 12.

[0058] The rear buttock-facing region B2, where the low-density region 46 is formed, faces the area near the wearer's buttocks where curvature becomes greatest when worn, and therefore curves significantly in the longitudinal direction. At this time, the highly flexible low-density region 46 receives compressive forces from the first rear compressed grooves 11 and the second rear compressed grooves 12, and is able to deform so as to bulge toward the top sheet 3. Therefore, the presence of the first rear compressed grooves 11 and the second rear compressed grooves 12 improves the fit to areas with a shallow or almost no gluteal cleft.

[0059] The degree of curvature of the convex shape located most rearward among the first rear compressed grooves 11, the degree of curvature of the low-density region 46 (degree of curvature of center line L), and the degree of curvature of the second rear compressed groove 12 can be made gentler in this order. That is, on the longitudinal center line CL, the radius of curvature of the center line of the rearmost convex shape of the first rear compressed groove 11, the radius of curvature of the above-mentioned center line L of the low-density region 46, and the radius of curvature of the center line of the second rear compressed groove 12 may increase toward the rear. This allows the rear buttocks-facing region B2 to fit closely to the shape of the rear buttocks without wrinkling or creases.

[0060] Furthermore, the provision of the first rear compressed groove 11 and the second rear compressed groove 12 can block the flow of bodily fluids rearward or diagonally rearward, enhancing the leakage prevention function of this embodiment. Also, the first rear compressed groove 11 and the second rear compressed groove 12 can serve as base points for bending the main body 8 when it is curved three-dimensionally along the buttocks, thereby improving the fit to the entire buttocks.

[0061] Although the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments. Furthermore, the above embodiments can be variously changed, modified, substituted, added, deleted, and combined within the scope of the claims, and these also fall within the technical scope of the present invention. [Explanation of symbols]

[0062] 1. Absorbent articles (sanitary napkins) 2 Back Seat 3 Topsheet 4. Absorber 4H High absorbent area 4L Low basis weight of absorbent body 4M Medium weight of absorbent body 7 Side seats 8. Main body (absorbent article main body) 10 Central compression groove 11 First rear compression groove 11' Planned location for the first rear compression groove 12 Second rear compression groove 12' Planned location for forming the second rear compression groove 13 Front compression groove 41 Absorbent body high pressure compression section 41A First absorber high-pressure compression section 41B Second absorbent body high-pressure compression section 42 absorbent body low compression section 45 High density area 46 Low density area (uncompressed area) 80 Compression type 81 High-pressure squeezing protrusion 82 Low-compression surface 86 Recess B Area opposite the buttocks B1 Anterior buttock opposing area (gluteal cleft opposing area) B2 Posterior buttock opposing area C Area facing body fluid outlet CL longitudinal centerline D1 Longitudinal direction D2 Lateral direction F Anterior area HF Hip Hold Flap M Middle area (opposite perineum area) WF Wing Flap

Claims

1. An absorbent article having an elongated main body including a skin-side top sheet, a non-skin-side back sheet opposite to the skin side, and an absorbent body disposed between the top sheet and the back sheet, the main body has a low-density region extending laterally across a longitudinal center line extending along the longitudinal direction of the absorbent article, at the rear of a buttocks-facing region that faces the buttocks of a wearer when worn, the low-density region being entirely surrounded by a high-density region having a higher density than the low-density region; An absorbent article wherein the densified region is a region that has been densified by compression.

2. the buttocks-facing region includes a uniform pulp weight region in which the pulp weight of the absorbent body is substantially uniform, The absorbent article according to claim 1 , wherein the low density region is partially formed within the uniform basis weight region.

3. The absorbent article of claim 1 , wherein the low density region has a rearwardly convex shape.

4. At least the top sheet and the absorbent body have compressed grooves recessed from the top sheet side, The absorbent article according to claim 1, wherein the compressed grooves include a first compressed groove extending laterally in front of the low-density region and a second compressed groove extending laterally behind the low-density region.

5. The absorbent article according to claim 4 , wherein each of the first compressed groove and the second compressed groove has a shape that includes a rearwardly convex shape.

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