Absorbent article and method for manufacturing absorbent element used therein

Abstract

To provide an absorbent article improving both of a backflow prevention property and diffusivity in a simple structure.SOLUTION: An absorbent article comprises an absorption element 50 including an absorber 56 provided in a longitudinal LD range including a crotch part M, and a packaging sheet 58 for packaging the absorber 56, where the absorber 56 is formed by mixing and accumulating pulp fibers and superabsorbent polymer particles. The absorption element 50 includes high compression parts 51 compressed in a thickness direction TD so as to dent from a surface of the absorption element 50 to the inside of the absorber 56, provided at intervals, and parts other than the high compression parts 51 in an arrangement area of the high compression parts 51 are non-high compression parts 52 that are thicker and have lower density than the high compression parts 51. An area rate of the high compression parts 51 in the arrangement area of the high compression parts 51 is 10-35%, and diameters of the largest inscribed circles 54 inscribed in outer shapes of the non-high compression parts 52 are 6.5 mm or less.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to an absorbent article such as a disposable diaper and a method for manufacturing an absorbent element used therein. [Background technology]

[0002] The absorbent body of an absorbent article (see, for example, Patent Document 1) is required to have various absorption properties, and typical examples of these are low return and high diffusion. Return is a phenomenon in which excreted liquid such as urine that has been absorbed by the absorbent body returns to the surface due to pressure or the like. Absorbent articles that are prone to return may cause a feeling of dampness after excretion or may unnecessarily stain the skin with excreted liquid. Therefore, low return is required for the absorbent body of an absorbent article.

[0003] Furthermore, in an absorbent body with low diffusivity, even if the absorbent body as a whole has a sufficient absorption capacity, only a portion of the absorbent body can be used for absorption, so after repeated absorption, the actual absorption capacity decreases, which may cause leakage. Therefore, high diffusivity is also required for the absorbent body of an absorbent article.

[0004] However, it has generally been difficult to improve both low backflow and high diffusibility. In other words, high diffusibility means that the liquid moves easily, i.e., backflow is easy.

[0005] Many proposals have been made to solve this problem, such as constructing an absorbent body with an upper layer that is less likely to backflow and a lower layer that has excellent diffusion properties, but many of these are complex and costly, so a simpler, lower-cost solution is desired. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5709584 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, a main object of the present invention is to improve both backflow prevention and diffusion with a simple structure. [Means for solving the problem]

[0008] The present inventors were conducting research into forming highly compressed portions compressed in the thickness direction in an absorbent body made by mixing and accumulating pulp fibers and superabsorbent polymer particles, when they accidentally discovered the possibility of improving both backflow prevention and diffusion. The absorbent article described below is based on this discovery. <First aspect> It has a crotch area, an absorbent element including an absorbent body provided in a front-rear direction range including the crotch area and a packaging sheet that wraps the absorbent body; The absorbent body is made by mixing and accumulating pulp fibers and highly absorbent polymer particles, The absorbent element has highly compressed portions compressed in the thickness direction so as to be recessed from the surface of the absorbent element to the inside of the absorbent body, the highly compressed portions being arranged at intervals, a portion other than the highly compressed portions in the arrangement region of the highly compressed portions is a non-highly compressed portion that is thicker and has a lower density than the highly compressed portions, the area ratio of the highly compressed portions in the arrangement region of the highly compressed portions is 10 to 35%, The diameter of the largest inscribed circle inscribed in the outer shape of the non-highly compressed portion is 6.5 mm or less. An absorbent article characterized by:

[0009] (Action and effect) The unique feature of this absorbent article is that it targets a general-purpose component, an absorbent body made by mixing and accumulating pulp fibers and superabsorbent polymer particles, and has highly compressed portions arranged more densely than conventional absorbent articles. Specifically, the highly compressed portions are high-density areas compressed in the thickness direction by pressure (direct pressure) to a nearly uniform thickness, and are the bottoms of depressions recessed from the surface of the absorbent element. Meanwhile, the non-highly compressed portions are thicker and less dense than the highly compressed portions. However, even in non-highly compressed portions, the absorbent body deforms as if pulled by the deformation of the highly compressed portions, resulting in an increase in density as it approaches the highly compressed portions. This results in a stronger capillary action in the highly compressed portions, which not only increases the liquid retention capacity compared to the surrounding area but also draws liquid toward the highly compressed portions. Therefore, by arranging the highly compressed portions more densely than conventional absorbent articles, more excreted liquid can be firmly retained in areas farther from the skin, making backflow less likely. Furthermore, by arranging the highly compressed portions more densely than before, the excrement absorbed in the absorbent body is subjected to suction force due to capillary action in the many surrounding highly compressed portions, causing the excrement to spread over a wider area. Furthermore, even in non-highly compressed areas, the absorbent body deforms near the periphery of the highly compressed areas as if pulled by the deformation of the highly compressed areas, which results in the advantage that the absorbent body becomes thinner than if there were no highly compressed areas. From these viewpoints, it is important that the area ratio of the highly compressed portions is within the above-mentioned range. It is also important that the diameter of the largest inscribed circle inscribed in the outer shape of the non-highly compressed portions is small so that the highly compressed portions are not sparsely arranged (so that the non-highly compressed portions do not continue long in all directions). It has been conventionally thought that arranging highly compressed portions closely together is not particularly desirable, so it was unexpected that such an effect would be achieved with the above-mentioned simple structure.

[0010] <Second aspect> The highly compressed portion has an outer shape that does not have an inflection point or a bending point, and the diameter of the largest inscribed circle inscribed in the outer shape of the highly compressed portion is 2 to 5 mm, and the circumferential length of the outer shape of the highly compressed portion is 1 to 2.5 times the circumferential length of the largest inscribed circle inscribed in the outer shape of the highly compressed portion. 1. An absorbent article according to a first embodiment.

[0011] (Action and effect) The dimensions and shape of the highly compressed portion can be determined as appropriate. However, because the highly compressed portion is a hard portion, if the dimensions of the highly compressed portion are excessively large, if the shape of the highly compressed portion is excessively long in one direction, or if the external shape is excessively intricate, the absorbent body as a whole may lack flexibility or may feel like a foreign object is mixed in the absorbent body (foreign body sensation). Furthermore, if the dimensions of the highly compressed portion are excessively small, if the shape of the highly compressed portion is excessively long in one direction, or if the external shape is excessively intricate, there is also the problem that the packaging sheet, when made of crepe paper, may be prone to tearing. Therefore, it is preferable that the dimensions and shape of the highly compressed portion be within the range of this embodiment.

[0012] <Third aspect> The basis weight of the pulp fibers in the absorbent body is 100 to 500 g / m 2 and the weight ratio of pulp fibers to superabsorbent polymer particles in the absorbent body is 45:55 to 65:35; The thickness of the non-highly compressed portion is 5 to 13 mm, The thickness of the highly compressed portion is 30 to 50% of the thickness of the non-highly compressed portion. The absorbent article according to the first or second aspect.

[0013] (Action and effect) Generally, to improve backflow prevention, the blend ratio of highly liquid-retentive superabsorbent polymer particles is often increased. In recent years, the blend ratio of highly absorbent polymer particles has also been increased in order to reduce the thickness of the absorbent body. However, increasing the blend ratio of highly absorbent polymer particles not only reduces the shape retention of the highly compressed sections, but also makes it difficult for the absorbent body to deform in areas near the highly compressed sections in non-highly compressed sections, as if pulled by the deformation of the highly compressed sections. This may make it difficult to improve backflow prevention and diffusibility. Furthermore, superabsorbent polymer particles that have absorbed and expanded excrement are more likely to adhere to each other, inhibiting the diffusion of excrement (gel blocking), which may make it difficult to improve diffusibility. Therefore, it is preferable to set the blend ratio of pulp fibers and superabsorbent polymer particles in the absorbent body within the range of this embodiment and to perform compression formation of the highly compressed sections within the range of this embodiment.

[0014] <Fourth aspect> In the arrangement region of the highly compressed portions, first virtual straight lines along a first direction are repeatedly arranged at first intervals in a second direction inclined by 80 to 90 degrees clockwise in a plan view with respect to the first virtual straight lines, and second virtual straight lines along the second direction are repeatedly arranged at second intervals in the first direction to define a virtual lattice; When the smallest imaginary rectangle having the intersection of the first imaginary line and the second imaginary line as a vertex is defined, the high-compression portion includes a first high-compression portion disposed at an intersection of the first imaginary straight line and the second imaginary straight line, a second high-compression portion disposed between adjacent first high-compression portions on the first imaginary straight line and between adjacent first high-compression portions on the second imaginary straight line, and a third high-compression portion disposed at an intersection of a diagonal of the imaginary rectangle, the first highly compressed portion has a circular shape centered at the intersection of the first virtual line and the second virtual line, the second highly compressed portion has a center of gravity at the midpoint of each side of the imaginary rectangle and is an ellipse or a rounded rectangle having a major axis along each side, The third highly compressed portion has a center of gravity at the intersection of the diagonals of the imaginary rectangle and is an ellipse or a rounded rectangle having a long axis along the front-to-rear direction, or a circle centered at the intersection of the diagonals of the imaginary rectangle. The absorbent article according to any one of the first to third aspects.

[0015] (Action and effect) The shape and arrangement pattern of the highly compressed portions in the arrangement region of the highly compressed portions may be determined as appropriate, but the pattern of this embodiment can improve the diffusivity in the longitudinal direction (first direction and second direction) of the second highly compressed portion, and has both a portion where the non-highly compressed portions are linearly connected in the first direction and a portion where the non-highly compressed portions are linearly connected in the second direction, so even if the individual highly compressed portions harden, the absorbent body as a whole will be able to easily deform to fit the body surface.

[0016] <Fifth aspect> The first highly compressed portion has a diameter of 1 to 4 mm, the second highly compressed portion has a major axis length of 3 to 6 mm and a minor axis length equal to the diameter of the first highly compressed portion; The third highly compressed portion has the same size and shape as the second highly compressed portion except that the direction of the major axis is along the front-rear direction, The minimum distance between the adjacent first highly compressed portion and the adjacent second highly compressed portion is 1 to 2 mm. An absorbent article according to a fourth embodiment.

[0017] (Action and effect) When arranging the highly compressed portions along the aforementioned virtual lattice, the dimensions of each highly compressed portion can be determined as appropriate, but it is preferable to keep them within the range of this embodiment, as this not only improves the anti-reverse properties and liquid diffusion properties, but also improves the ease of deformation of the absorbent body.

[0018] <Sixth aspect> The virtual grid forms an oblique grid shape in which the first virtual straight lines are inclined by 40 to 50 degrees clockwise with respect to the front-to-rear direction in a plan view, and the second virtual straight lines are inclined by 40 to 50 degrees counterclockwise with respect to the front-to-rear direction in a plan view. The absorbent article of the fourth or fifth aspect.

[0019] (Action and effect) When arranging the highly compressed portions along a virtual lattice as described above, it is preferable to arrange them in a diagonal lattice pattern as in this embodiment, as this not only makes the absorbent body easier to deform when worn, but also provides excellent liquid diffusion properties.

[0020] <Seventh aspect> A method for manufacturing an absorbent element having an absorbent body made by mixing and accumulating pulp fibers and superabsorbent polymer particles, and a packaging sheet for wrapping the absorbent body, comprising: a first step of forming an absorbent body by mixing and accumulating the pulp fibers and the superabsorbent polymer particles; a second step of forming a package by wrapping the entire absorbent body in a packaging sheet; a third step of sandwiching the package between an anvil roll having projections arranged at intervals on its outer circumferential surface and a smooth roll having a cylindrical surface facing the anvil roll, and pressing the portion of the package sandwiched between the many projections of the anvil roll and the smooth roll so that it is recessed from the surface of the package into the absorbent body; When the arrangement of the tip surfaces of the protrusions on the anvil roll is developed on a plane, the area ratio of the tip surfaces of the protrusions in the arrangement region of the tip surfaces is 10 to 35%, and the diameter of the largest inscribed circle inscribed in the outer shape of the part other than the tip surfaces in the arrangement region of the tip surfaces is 6.5 mm or less. A method for manufacturing an absorbent element, comprising:

[0021] (Action and effect) This provides the same effects as the first embodiment. [Effects of the Invention]

[0022] The present invention provides advantages such as improved backflow prevention and diffusion with a simple structure. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a plan view showing the inner surface of the pants-type disposable diaper in an unfolded state. [Figure 2] FIG. 2 is a plan view showing the outer surface of the pants-type disposable diaper in an unfolded state. [Figure 3] 2 is a cross-sectional view taken along line 2-2 of FIG. 1. [Figure 4] 3 is a cross-sectional view of FIG. 1 taken along line 3-3. [Figure 5] 1(a) is a cross-sectional view taken along line 4-4 in FIG. 1, and FIG. 1(b) is a cross-sectional view taken along line 5-5 in FIG. [Figure 6] FIG. 1 is a perspective view of a pants-type disposable diaper. [Figure 7] FIG. 2 is a plan view showing the outer surface of the inner body in the deployed state together with the outline of the outer body. [Figure 8] FIG. 2 is a plan view showing the surface of the absorbent body together with the outline of the packaging sheet. [Figure 9] FIG. 2 is a cross-sectional view of an absorbent element. [Figure 10] FIG. [Figure 11] FIG. 2 is an enlarged plan view showing a main part of the surface of the absorbent element. [Figure 12] FIG. 10 is a plan view showing another example of the absorbent body. [Figure 13] FIG. 3 is a cross-sectional view showing the absorbent element in a state before the absorbent body is wrapped in a wrapping sheet. [Figure 14] FIG. 3 is a cross-sectional view showing the absorbent element in a state after the absorbent body has been wrapped in a wrapping sheet and before the highly compressed portion has been formed. [Figure 15] FIG. 10 is a cross-sectional view of another absorbent element. [Figure 16] FIG. 2 is an enlarged plan view showing a main part of the surface of the absorbent element. [Figure 17] FIG. 2 is an enlarged plan view showing a main part of the surface of the absorbent element. [Figure 18] FIG. 2 is an enlarged plan view showing a main part of the surface of the absorbent element. [Figure 19] FIG. 2 is an enlarged plan view showing a main part of the surface of the absorbent element. [Figure 20] FIG. 2 is an enlarged plan view showing a main part of the surface of the absorbent element. [Figure 21] FIG. 2 is an enlarged plan view showing a main part of the surface of the absorbent element. [Figure 22] 1A to 1C are schematic diagrams illustrating a method for manufacturing an absorbent element. [Figure 23] FIG. 10 is an explanatory diagram of a method for measuring the depth of a highly compressed portion. DETAILED DESCRIPTION OF THE INVENTION

[0024] Below, a pants-type disposable diaper will be described in detail as an example of an absorbent article, with reference to the accompanying drawings. Adjacent components in the thickness direction are fixed or joined as needed, in addition to the fixed or joined portions described below, in the same manner as known diapers. The dotted patterns in the cross-sectional diagram indicate adhesives such as hot melt adhesives used as the fixing or joining means. Hot melt adhesives can be applied by known methods, such as slot coating, continuous or dotted bead coating, spiral, Z-shaped, or wavy spray coating, or pattern coating (transfer of hot melt adhesive using a relief printing method). Alternatively or in addition to this, hot melt adhesive can be applied to the outer surface of the elastic member to fix the elastic member to the adjacent member. Hot melt adhesives include, for example, EVA-based, adhesive rubber-based (elastomer-based), polyolefin-based, and polyester / polyamide-based types, but no particular limitation is imposed on them. Material welding methods such as heat sealing and ultrasonic sealing can also be used to fix or join the components. In areas where liquid permeability in the thickness direction is required, adjacent components in the thickness direction are fixed or joined in an intermittent pattern. For example, when such intermittent fixing or joining is performed using a hot melt adhesive, intermittent pattern application such as a spiral, Z-shape, or wavy pattern can be suitably used. When applying to an area greater than the application width of a single nozzle, intermittent pattern application such as a spiral, Z-shape, or wavy pattern can be performed with or without gaps in the width direction. Material welding methods such as heat sealing and ultrasonic sealing can also be used to join the components.

[0025] Furthermore, as the nonwoven fabric in the following description, known nonwoven fabrics can be used as appropriate depending on the location and purpose. The constituent fibers of the nonwoven fabric can be selected without particular limitation, for example, synthetic fibers such as polyolefins (e.g., polyethylene or polypropylene), polyesters, and polyamides (including single-component fibers as well as core-sheath and other composite fibers), regenerated fibers (e.g., rayon or cupra), and natural fibers (e.g., cotton), and mixtures of these can also be used. To increase the flexibility of the nonwoven fabric, it is preferable to use crimped fibers as the constituent fibers. Furthermore, the constituent fibers of the nonwoven fabric can be hydrophilic fibers (including fibers made hydrophilic by a hydrophilizing agent), hydrophobic fibers, or water-repellent fibers (including fibers made water-repellent by a water-repellent agent). Furthermore, nonwoven fabrics are generally classified into staple fiber nonwoven fabrics, long fiber nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, thermal bond (air-through) nonwoven fabrics, needle-punched nonwoven fabrics, point-bond nonwoven fabrics, laminated nonwoven fabrics (including SMS nonwoven fabrics and SMMS nonwoven fabrics in which a meltblown layer is sandwiched between spunbond layers), etc. depending on the fiber length, sheet formation method, fiber bonding method, and laminated structure, and any of these nonwoven fabrics can be used.

[0026] 1 to 6 show an example of a pants-type disposable diaper. This pants-type disposable diaper includes a rectangular front outer body 12F constituting a front waist-surrounding portion, a rectangular rear outer body 12B constituting a rear waist-surrounding portion, and an inner body 200 provided inside the outer bodies 12F and 12B so as to extend from the front outer body 12F through the crotch region M to the rear outer body 12B. Side seals 12A are formed by joining both sides of the front outer body 12F and both sides of the rear outer body 12B, and thus an opening formed by the front and rear ends of the outer bodies 12F and 12B serves as a waist opening WO through which the wearer's waist passes. The portions of the inner body 200 on both widthwise sides, surrounded by the lower edges of the outer bodies 12F and 12B and the side edges of the inner body 200, serve as leg openings LO through which the legs pass. The inner body 200 absorbs and retains excrement such as urine, and the outer bodies 12F and 12B support the inner body 200 against the wearer's body. Furthermore, the symbol Y indicates the total length of the diaper in the unfolded state (the length in the front-to-back direction from the edge of the waist opening WO of the front body F to the edge of the waist opening WO of the back body B), and the symbol X indicates the total width of the diaper in the unfolded state.

[0027] This pants-type disposable diaper has a waist region T defined as the front-to-back range having the side seals 12A (the front-to-back range from the waist opening WO to the top of the leg openings LO), and an intermediate region L defined as the front-to-back range of the portion forming the leg openings LO (between the front-to-back region having the side seals 12A of the front body F and the front-to-back region having the side seals 12A of the back body B). The portions of the front exterior body 12F and the rear exterior body 12B located in the waist region T, i.e., the front waist portion and the rear waist portion, can be conceptually divided into a "waist portion" W that forms the edge of the waist opening, and a "lower waist portion" U that is the portion below this. Typically, when the front and rear waist regions have a boundary where the stretch stress in the width direction WD changes (e.g., where the thickness or elongation rate of the elastic member changes), the waist region W is the portion closer to the waist opening WO than the boundary closest to the waist opening WO. When no such boundary exists, the waist region W is the waist extension 12E extending further toward the waist opening WO than the absorbent body 56 or inner body 200. Their front-to-rear lengths vary depending on the product size and can be determined as appropriate. For example, the waist region W may be 15 to 40 mm, and the lower waist region U may be 65 to 120 mm. Meanwhile, both side edges of the middle region L are constricted in a U-shape or curved shape to fit around the wearer's legs, and these are the areas into which the wearer's legs are inserted. As a result, the pants-type disposable diaper in its unfolded state has a generally hourglass shape overall.

[0028] (exterior body) As shown in the figure, the outer coverings 12F, 12B consist of a rectangular front outer covering 12F that forms at least the waistline of the front body F, and a rectangular back outer covering 12B that forms at least the waistline of the back body B. The front outer covering 12F and the rear outer covering 12B may not be continuous at the crotch side and may be spaced apart in the front-to-back direction LD (two-piece outer covering type), or may be continuous from the front body to the back body (integrated outer covering type), as not shown. In the two-piece outer covering type, the front-to-back distance 12d may be, for example, approximately 40 to 60% of the total length Y. In the figure, the lower edges of the front outer covering 12F and the rear outer covering 12B are linear along the width direction WD, but the lower edge of at least one of the front outer covering 12F and the rear outer covering 12B may be curved to fit around the legs.

[0029] In a two-piece outer-casing pants-type disposable diaper, the inner body 200 is exposed between the front outer body 12F and the rear outer body 12B. Therefore, to prevent the liquid-impermeable sheet 11 from being exposed on the back surface of the inner body 200, a cover nonwoven fabric 13 is preferably provided on the back surface of the inner body 200, extending from between the front outer body 12F and the inner body 200 to between the rear outer body 12B and the inner body 200. The inner and outer surfaces of the cover nonwoven fabric 13 can be bonded to their respective opposing surfaces with a hot-melt adhesive. The nonwoven fabric used for the cover nonwoven fabric 13 can be selected appropriately from a material similar to that of the outer bodies 12F and 12B. Although not shown, the outer body may be continuous from the front body F to the back body B, passing through the crotch area. In this case, the outer body will have not only a portion corresponding to the waist region T but also a portion corresponding to the middle region L.

[0030] The front exterior body 12F and the rear exterior body 12B have a front waist portion and a rear waist portion that form the waist region T. In the example shown in Figures 1 and 2, the front exterior body 12F and the rear exterior body 12B have the same dimensions in the front-to-rear direction LD, and the front exterior body 12F and the rear exterior body 12B do not have a portion corresponding to the middle region L, but as shown in Figure 7, the rear exterior body 12B may have a longer dimension in the front-to-rear direction than the front exterior body 12F, and the front exterior body 12F does not have a portion corresponding to the middle region L, but the rear exterior body 12B may have a buttocks cover portion C extending from the waist region T toward the middle region L. Although not shown, the front exterior body 12F may also be provided with a groin cover portion extending from the waist region T toward the middle region L.

[0031] As shown in Figures 4 and 5, the exterior bodies 12F, 12B are formed by joining an outer sheet layer and an inner sheet layer adjacent to the outer and inner sides of the elastic members 16-19 (described later) using a joining method such as a hot melt adhesive or welding. The outer sheet layer and the inner sheet layer can be formed from two sheets 12S, 12H as shown in the illustrated example, or from a single sheet material. For example, in the latter case, the inner sheet layer and the outer sheet layer are respectively formed by the inner and outer portions of a single sheet material folded back at the edge of the waist opening WO (which may be the edge on the crotch side) in part or all of the exterior bodies 12F, 12B. The illustrated example shows the former case, in which the sheet material 12S forming the outer sheet layer in the lower waist portion is folded back around the waist opening WO side of the sheet material 12H forming the inner sheet layer in the lower waist portion and folded back inward, with this folded back portion 12r extending to cover the edge of the interior body 200 on the waist opening WO side. On the other hand, in the waist portion, the folded portion 12r serves as an inner sheet layer adjacent to the inside of the elastic member.

[0032] The exterior bodies 12F, 12B incorporate elastic members 16-19 to improve the fit around the wearer's waist, and form a stretchable region A2 that stretches elastically in the width direction WD in response to the stretching of the elastic members 16-19. In this stretchable region A2, the exterior bodies 12F, 12B contract in their natural length state as the elastic members contract, forming wrinkles or creases. When stretched in the longitudinal direction of the elastic members, they can be stretched to a predetermined stretch rate without wrinkles. The elastic members 16-19 can be elongated elastic members such as rubber threads (illustrated example), as well as known elastic members in strip, net, film, and other shapes, without any particular limitation. The elastic members 16-19 may be made of synthetic or natural rubber.

[0033] To explain the elastic members 16-19 in the illustrated example in more detail, a plurality of waist elastic members 17 are attached to the waist portion W of the outer bodies 12F, 12B at intervals in the front-to-rear direction so as to be continuous over the entire width direction WD. Of the waist elastic members 17, one or more arranged in the region adjacent to the lower waist portion U may overlap the inner body 200, or may be provided on both sides in the width direction except for the central portion in the width direction that overlaps with the inner body 200. The waist elastic members 17 should have a thickness of 155-1880 dtex, particularly about 470-1240 dtex (in the case of synthetic rubber; in the case of natural rubber, a cross-sectional area of ​​0.05-1.5 mm). 2 , especially 0.1 to 1.0 mm 2 It is preferable to provide about 2 to 15, and especially about 4 to 10, rubber threads of about 1 / 4" thick (approximately 1 / 4" thick) at intervals of 2 to 12 mm, especially 3 to 7 mm, and the resulting elongation rate in the width direction WD of the waist portion W is preferably about 150 to 400%, especially about 220 to 320%. Furthermore, it is not necessary for the waist portion W to use elastic members of the same thickness or to have the same elongation rate all along the front-to-back direction LD, and for example, the thickness or elongation rate may be different in some areas.

[0034] Additionally, a plurality of lower waist elastic members 16, 19 made of elongated elastic members are attached to the lower waist portion U of the exterior bodies 12F, 12B at intervals in the front-to-back direction to form a lower waist stretchable region (a region having lower waist elastic members 16, 19). The lower waist elastic members 16, 19 have a thickness of 155 to 1880 dtex, particularly about 470 to 1240 dtex (in the case of synthetic rubber, or a cross-sectional area of ​​0.05 to 1.5 mm in the case of natural rubber). 2 , especially 0.1 to 1.0 mm 2 It is preferable to provide about 5 to 30 elastic threads of about 100 mm thick (approximately 1 / 2" thick) at intervals of 1 to 15 mm, especially 3 to 8 mm, and the resulting elongation rate in the width direction WD of the waist lower portion U is preferably about 200 to 350%, especially about 240 to 300%. Furthermore, it is not necessary for the waist lower portion U to use elastic members of the same thickness or have the same elongation rate all over its front-to-back direction LD, and thicknesses and elongation rates may vary in some areas.

[0035] When elastic members 16, 19 are provided in the front-to-back range including the absorbent body 56, as in the lower waist portion U in the illustrated example, in order to prevent contraction of the absorbent body 56 in the width direction WD in part or all of the region, it is preferable to designate the widthwise middle portion, including part or all of the portion overlapping with the absorbent body 56, as a non-elasticated region A1, and designate both widthwise sides of this as elasticated regions A2 (in the illustrated example, these are lower-waist elasticated regions). The widthwise dimension of the elasticated regions A2 provided on both sides of the non-elasticated region A1 may be substantially constant in the front-to-back direction LD as in the illustrated example, or may vary in the front-to-back direction LD, although not shown. Furthermore, the widthwise dimension of the elasticated regions A2 provided on both sides of the non-elasticated region A1 in the width direction WD may be substantially the same in the front body portion F and the back body portion B, or may be different.

[0036] The stretchable region A2 and non-stretchable region A1 can be constructed by attaching elastic members 16-17, 19 between the inner and outer sheet layers, and then cutting the elastic members 16, 19 into small pieces by applying pressure and heat or cutting them at one location in the middle of the width of the region that will become the non-stretchable region A1, or across almost the entire region, leaving stretchability in the stretchable region A2 while eliminating stretchability in the non-stretchable region A1. Note that unnecessary elastic members 18 that do not substantially contribute to the formation of stretchability will remain in the non-stretchable region A1.

[0037] The sheet materials 12S, 12H forming the inner and outer sheet layers can be used without any particular limitation, but nonwoven fabric is preferred. When nonwoven fabric is used, the basis weight per sheet is 10 to 30 g / m 2 It is preferable to set it to about this level.

[0038] The elastic members 16-19 can be fixed to the exterior bodies 12F, 12B by known methods. The inner sheet layer and the outer sheet layer can also be joined to each other by known methods. For example, in the portions of the exterior bodies 12F, 12B having the elastic members 16-19, a hot melt adhesive HM can be applied only to the outer peripheral surfaces of the elastic members 16-19 using an application means such as a comb gun or a SureWrap nozzle, and the elastic members can then be sandwiched between the inner sheet layer and the outer sheet layer. The hot melt adhesive HM applied only to the outer peripheral surfaces of the elastic members 16-19 can then be used to fix the elastic members 16-19 to the inner sheet layer and the outer sheet layer, and the inner sheet layer and the outer sheet layer together.

[0039] (Interior body joint) The inner body 200 can be joined to the outer bodies 12F, 12B by a joining method that uses material welding, such as heat sealing or ultrasonic sealing, or by a hot melt adhesive. In the illustrated example, the inner body 200 is fixed to the inner surfaces of the outer bodies 12F, 12B via a hot melt adhesive that is applied to the back surface of the inner body 200, that is, in this case, the back surface of the liquid-impermeable sheet 11 and the base portions 65 of the rising gathers 60. The inner body joining portion 20 that joins the inner body 200 and the outer bodies 12F, 12B can be provided over almost the entire overlapping area, as shown in Figure 2, and can also be provided in a portion excluding both widthwise ends of the inner body 200, for example.

[0040] (interior body) The inner body 200 can have any shape, but in the illustrated example, it is a rectangle with its long sides along the front-to-back direction LD. As shown in Figures 3 to 5, the inner body 200 comprises a top sheet 30 that faces the body, a liquid-impermeable sheet 11, and an absorbent element 50 interposed therebetween. Reference numeral 40 denotes an intermediate sheet (second sheet) that is provided between the top sheet 30 and the absorbent element 50 in order to quickly transfer liquid that has permeated the top sheet 30 to the absorbent element 50, and reference numeral 60 denotes rising gathers 60 that extend from both sides of the inner body 200 so as to come into contact with the wearer's legs in order to prevent excrement from leaking out the sides of the inner body 200.

[0041] (Top sheet) The top sheet 30 is liquid-permeable, and examples thereof include a perforated or non-perforated nonwoven fabric and a perforated plastic sheet. The top sheet 30 may consist of a single sheet, or a laminated sheet obtained by bonding two or more sheets together. Similarly, the top sheet 30 may consist of a single sheet, or two or more sheets in the planar direction.

[0042] The side edges of the top sheet 30 may be folded back at the side edges of the absorbent element 50, or may not be folded back and may extend out to the sides beyond the side edges of the absorbent element 50.

[0043] The top sheet 30 is preferably fixed to an adjacent backside member by a material welding joining means such as heat sealing or ultrasonic sealing, or by a hot melt adhesive, in order to prevent misalignment relative to the backside member, etc. In the illustrated example, the top sheet 30 is fixed to the surface of the intermediate sheet 40 and the surface of the portion of the packaging sheet 58 that is located on the front side of the absorbent body 56 by a hot melt adhesive applied to the backside of the top sheet 30.

[0044] (middle seat) In order to quickly transfer liquid that has passed through the top sheet 30 to the absorbent body 56, an intermediate sheet (also called a second sheet) 40, which has a faster liquid permeation rate than the top sheet 30, can be provided. This intermediate sheet 40 is intended to quickly transfer liquid to the absorbent body 56, improving the absorption performance of the absorbent body 56 and reducing backflow from the absorbent body 56. The intermediate sheet 40 can also be omitted.

[0045] Examples of the intermediate sheet 40 include the same material as the top sheet 30, spunlace nonwoven fabric, spunbond nonwoven fabric, SMS nonwoven fabric, pulp nonwoven fabric, a mixed sheet of pulp and rayon, point-bond nonwoven fabric, and crepe paper. Air-through nonwoven fabric is particularly preferred because of its bulkiness. For the air-through nonwoven fabric, it is preferable to use composite fibers with a core-sheath structure, and in this case, the resin used for the core may be polypropylene (PP), but polyester (PET) with high rigidity is preferred. The basis weight is 17 to 80 g / m 2 is preferable, and 25 to 60 g / m 2 The thickness of the raw material fibers of the nonwoven fabric is preferably 2.0 to 10 dtex. In order to make the nonwoven fabric bulky, it is also preferable to use eccentric fibers, hollow fibers, or eccentric and hollow fibers as all or part of the raw material fibers.

[0046] In the illustrated example, the intermediate sheet 40 is positioned in the center and is shorter than the width of the absorbent body 56, but it may be provided across the entire width. The length of the intermediate sheet 40 in the front-to-rear direction may be the same as the entire length of the diaper, the same as the length of the absorbent element 50, or may be within a short length range centered on the liquid-receiving region.

[0047] In order to prevent the intermediate sheet 40 from shifting relative to the backside member, it is desirable to fix the intermediate sheet 40 to the backside adjacent member by a joining means that uses material welding such as heat sealing or ultrasonic sealing, or by a hot melt adhesive. In the illustrated example, the intermediate sheet 40 is fixed to the surface of the portion of the packaging sheet 58 that is located on the front side of the absorbent body 56 by a hot melt adhesive applied to the backside of the intermediate sheet 40.

[0048] (Liquid-impermeable sheet) The material of the liquid-impermeable sheet 11 is not particularly limited, but examples thereof include a plastic film made of a polyolefin resin such as polyethylene or polypropylene, a laminated nonwoven fabric in which a plastic film is provided on the surface of a nonwoven fabric, and a laminated sheet in which a nonwoven fabric or the like is overlaid and bonded to a plastic film. A liquid-impermeable and moisture-permeable material, which is preferred from the viewpoint of preventing stuffiness, is preferably used for the liquid-impermeable sheet 11. A widely used moisture-permeable plastic film is a microporous plastic film obtained by kneading an inorganic filler into a polyolefin resin such as polyethylene or polypropylene, forming the sheet, and then stretching the sheet in a uniaxial or biaxial direction. In addition, nonwoven fabrics using microdenier fibers, nonwoven fabrics whose leak-proofing properties have been enhanced by reducing the voids in the fibers through the application of heat or pressure, and sheets that have been made liquid-impermeable without using a plastic film by coating with a highly absorbent resin or a hydrophobic resin or a water-repellent agent can also be used as the liquid-impermeable sheet 11, but it is preferable to use a resin film in order to obtain sufficient adhesive strength when bonding with the cover nonwoven fabric 13 described below via a hot melt adhesive.

[0049] The liquid-impermeable sheet 11 is made to have a width that fits behind the absorbent element 50 as shown in the figure, and in order to improve leakproofness, it can also be made to wrap around both sides of the absorbent element 50 and extend to both sides of the absorbent element 50 on the side of the top sheet 30. The appropriate width of this extension is about 5 to 20 mm on each side.

[0050] (Absorption element) The absorbent element 50 has an absorbent body 56 and a packaging sheet 58 that wraps the entire absorbent body 56. The absorbent element 50 has a crotch region M and portions extending to the front and rear of the crotch region M.

[0051] (absorbent) The absorbent body 56 is a mixture of pulp fibers and highly absorbent polymer particles, which are uniformly distributed throughout the absorbent body 56. The basis weight of the pulp fibers is, for example, 100 to 500 g / m 2 The absorbent body 56 is preferably a mixture and accumulation of only pulp fibers and superabsorbent polymer particles, but may contain trace amounts of additives such as deodorants and fragrances as long as they do not impede the improvement of backflow prevention and diffusion properties, which will be described later.

[0052] The term "superabsorbent polymer particles" includes not only "particles" but also "powder." The superabsorbent polymer particles used in this type of disposable diaper can be used as is. For example, when sieved using a 500 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), the percentage of particles remaining on the sieve is preferably 30% by weight or less. Furthermore, when sieved using a 180 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), the percentage of particles remaining on the sieve is preferably 60% by weight or more.

[0053] The material of the superabsorbent polymer particles is not particularly limited, but a water absorption capacity of 40 g / g or more is preferred. Examples of superabsorbent polymer particles include starch-based, cellulose-based, and synthetic polymer-based materials, such as starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, crosslinked products of sodium carboxymethylcellulose, and acrylic acid (salt) polymers. The shape of the superabsorbent polymer particles is preferably the commonly used powder-like form, but other shapes can also be used.

[0054] The highly absorbent polymer particles preferably have a water absorption rate of 70 seconds or less, particularly 40 seconds or less. If the water absorption rate is too slow, the liquid supplied into the absorbent body 56 tends to flow back out of the absorbent body 56, which is known as backflow.

[0055] Furthermore, the highly absorbent polymer particles preferably have a gel strength of at least 1000 Pa. This effectively prevents the sticky feeling after absorbing liquid, even when the absorbent body 56 is bulky.

[0056] The basis weight of the highly absorbent polymer particles can be determined appropriately depending on the absorption amount required for the application of the absorbent body 56. Therefore, although it cannot be generalized, it is generally in the range of 50 to 350 g / m 2 The polymer weight can be 50 g / m 2 If it is less than 350g / m, it will be difficult to ensure sufficient absorption. 2 Above this, the effect saturates.

[0057] The ratio of fibers to superabsorbent polymer particles in the absorbent body 56 is not particularly limited, and can be, for example, a weight ratio of fibers:superabsorbent polymer particles of 40:60 to 65:35.

[0058] The thickness 56t of the absorber 56 is not particularly limited, but can be set to 5 to 13 mm.

[0059] The absorbent body 56 may extend across both the front and rear of the crotch region M so as to include the crotch region M. In the case of a pants-type disposable diaper such as this example, it is preferable that the absorbent body 56 extends to or near the peripheral edge of the inner body 200 in both the front-to-rear direction LD and the width direction WD. The reference symbol 56X indicates the overall width of the absorbent body 56.

[0060] To ensure a sufficient absorption capacity in the crotch region M, it is preferable that the absorber 56 has a substantially rectangular shape as shown in the example of Fig. 8. Furthermore, to improve the fit in the crotch region M, it is also possible to make the width of the absorber 56 in the crotch region M narrower than the front and rear sides, giving it a constricted shape, as shown in the example of Fig. 12(a). In this case, to ensure a sufficient absorption capacity in the crotch region M, it is preferable that the width n1 of the narrowest part of the absorber 56 in the crotch region M be 0.85 times or more the overall width 56X of the absorber 56.

[0061] The crotch region M refers to the area in the front-to-back direction LD where the absorbent body 56 has a constricted portion 56n (described later); if the absorbent body 56 does not have a constricted portion 56n but the diaper has a constricted portion in its unfolded state as in the illustrated example, the crotch region M refers to the area in the front-to-back direction LD where the constricted portion of the diaper's outer shape is located (between the front exterior body 12F and the rear exterior body 12B in the illustrated example); if the diaper does not have any constricted portions, the crotch region M refers to the area located in the center in the front-to-back direction LD where the dimension in the front-to-back direction LD is 20-30% of the total length of the product. The portions extending forward and backward from the crotch region M are the front portion and the rear portion, respectively.

[0062] (Low basis weight part) The absorbent body 56 may have elongated low basis weight sections 56L extending in the front-to-rear direction LD on both sides of the width direction WD in the crotch region M, as shown in the examples in Figures 1 to 4, or may not have low basis weight sections 56L (not shown). The low basis weight sections 56L refer to sections with a low basis weight and do not include sections that are compressed in the thickness direction TD but have no change in basis weight, such as the highly compressed sections 51 described below. The low basis weight sections 56L can be slits that penetrate the thickness direction TD, but are preferably recesses with a low accumulation of pulp fibers and superabsorbent polymer particles, as shown in the example, because this facilitates ensuring sufficient absorption. The recesses may be formed on either the front or back surface of the absorbent body 56. Providing such low basis weight sections 56L in the absorbent body 56 encourages bending of the absorbent body 56 along the low basis weight sections 56L, improving the fit of the absorbent element 50 in the crotch region M. The total basis weight of the pulp fibers and superabsorbent polymer particles in the low basis weight portion 56L may be less than the total basis weight of the pulp fibers and superabsorbent polymer particles in the portions other than the low basis weight portion 56L, and may be, for example, 0.1 to 0.5 times the total basis weight of the pulp fibers and superabsorbent polymer particles in the portions other than the low basis weight portion 56L.

[0063] As long as the low basis weight portion 56L is elongated in the front-to-rear direction LD, it may extend linearly along the front-to-rear direction LD, or it may be curved so that it is positioned laterally as it approaches both sides in the front-to-rear direction LD, as in the illustrated example. The front and rear ends of the low basis weight portion 56L may have any suitable shape. For example, it may be linear as in the example shown in FIG. 12(a), or it may be curved (e.g., semicircular) as in the example shown in FIG. 8, or it may have rounded corners at both ends and a linear middle portion (not shown). The width m1 of the low basis weight portion 56L may be determined as appropriate, and may be 0.04 to 0.1 times the width n1 (meaning the overall width 56X in the case of a rectangle) of the narrowest portion of the crotch region M of the absorbent body 56. The width m1 of the low basis weight portion 56L may be constant or variable along its length. The dimensions and arrangement of the low basis weight portion 56L in the front-to-rear direction LD may be determined as appropriate. For example, the dimension m2 of the low basis weight portion 56L in the front-to-back direction LD can be 50 to 120%, and more preferably 50 to 80%, of the dimension of the crotch region M in the front-to-back direction LD. The low basis weight portion 56L may be contained within the crotch region M, or may extend to the front, back, or both the front and back of the crotch region M.

[0064] As shown in FIG. 8, the low basis weight portion 56L may be provided on each side of the crotch region M in the width direction WD, and one may be provided in the center of the width direction WD. Alternatively, as shown in FIG. 12(a), only one may be provided in the center, or as shown in FIG. 12(b), only one may be provided on each side of the crotch region M in the width direction WD.

[0065] (High compression section) As shown in Figures 3, 4, and 9 to 11, the absorbent element 50 has highly compressed portions 51 compressed in the thickness direction TD arranged at intervals from the surface of the absorbent element 50 to the inside of the absorbent body 56. Furthermore, within the region where the highly compressed portions 51 are arranged (a rectangular region with sides along the front-to-rear direction LD and the width direction WD, respectively, and circumscribing all of the arranged highly compressed portions 51), the portions other than the highly compressed portions 51 are non-highly compressed portions 52 that are thicker and lower in density than the highly compressed portions 51. The highly compressed portions 51 are high-density portions that have been compressed by pressure (direct pressure) and have approximately the same thickness, and form the bottoms of the depressions. Meanwhile, the non-highly compressed portions 52 are thicker and lower in density than the highly compressed portions 51, but even in the non-highly compressed portions 52, the absorbent body 56 deforms in the vicinity of the highly compressed portions 51 as if pulled by the deformation of the highly compressed portions 51, resulting in an increase in density as they approach the highly compressed portions 51. As long as the non-highly compressed portions 52 are thicker and less dense than the highly compressed portions 51, they may be partially or entirely compressed in the thickness direction TD simultaneously with, before, or after the formation of the highly compressed portions 51. It is preferable that the non-highly compressed portions 52 do not have depressions on either or both of the front and back surfaces of the absorbent element 50, but as long as they are thicker and less dense than the highly compressed portions 51, they may have depressions on either or both of the front and back surfaces of the absorbent element 50.

[0066] The highly compressed portions 51 may be provided over the entire front-rear and width directions of the absorbent element 50 (i.e., the entire surface of the absorbent element 50 is the arrangement region of the highly compressed portions 51), or they may be provided only in a portion of the front-rear direction or a portion of the width direction of the absorbent element 50. For example, although not shown, the highly compressed portions 51 may be provided only in a middle region in the front-rear direction LD that includes the crotch region M, or conversely, the highly compressed portions 51 may not be provided in the middle region in the front-rear direction LD that includes the crotch region M, but may be provided only in regions on both the front and rear sides of that middle region. Furthermore, although the highly compressed portions 51 in the illustrated example do not recess from the surface of the sheet located on the front side of the absorbent element (in the illustrated example, the top sheet 30 and intermediate sheet 40) into the absorbent body 56, they may be recessed from the surface of the absorbent element 50 into the absorbent body 56 as a result of being pressed from the sheet located on the front side of the absorbent element so as to recess into the absorbent body 56.

[0067] The area ratio of the highly compressed portions 51 in the region where the highly compressed portions 51 are arranged (total area of ​​the highly compressed portions 51 / area of ​​the region where the highly compressed portions 51 are arranged) is preferably 10 to 35%, and more preferably 20 to 35%. The diameter of the largest inscribed circle 54 inscribed in the outer shape of the non-highly compressed portions 52 is preferably 6.5 mm or less, more preferably 6 mm or less, and particularly preferably 5 mm or less. Furthermore, the lower limit of the diameter of the largest inscribed circle 54 inscribed in the outer shape of the non-highly compressed portions 52 is preferably 4 mm.

[0068] The highly compressed portions 51 are high-density portions where the absorbent element 50 is compressed in the thickness direction TD by pressure (direct pressure) and has a substantially uniform thickness, and are the bottoms of depressions recessed from the surface of the absorbent element 50. On the other hand, the non-highly compressed portions 52 are portions that are thicker and have a lower density than the highly compressed portions 51. However, even in the non-highly compressed portions 52, the absorbent body 56 deforms near the periphery of the highly compressed portions 51 as if pulled by the deformation of the highly compressed portions 51, and as a result, the density increases as it approaches the highly compressed portions 51. For this reason, capillary action is strongly expressed in the highly compressed portions 51, and not only does the liquid retention capacity become higher than in the surrounding area, but liquid is also drawn toward the highly compressed portions 51. Therefore, if the highly compressed portions 51 are arranged more densely than before, more excreted liquid can be firmly retained in areas farther from the skin, making it less likely for backflow to occur. Furthermore, when the highly compressed portions 51 are arranged more densely than before, the capillary suction force of the many surrounding highly compressed portions 51 acts on the excrement absorbed in the absorbent body 56, causing the excrement to spread over a wider area. Furthermore, even in the presence of non-highly compressed portions 52, the absorbent body 56 deforms near the periphery of the highly compressed portions 51 as if pulled by the deformation of the highly compressed portions 51, resulting in an advantage that the absorbent body 56 becomes thinner than when there are no highly compressed portions 51. From these perspectives, it is important that the area ratio of the highly compressed portions 51 is within the above-mentioned range. It is also important that the diameter of the largest inscribed circle 54 inscribed in the outer shape of the non-highly compressed portions 52 is small so that the highly compressed portions 51 are not arranged sparsely (so that the non-highly compressed portions 52 do not continue long in all directions).

[0069] The dimensions and shape of the highly compressed portions 51 can be determined as appropriate. However, because the highly compressed portions 51 are hard, if the dimensions of the highly compressed portions 51 are excessively large, if the shape of the highly compressed portions 51 is excessively long in one direction, or if the shape of the highly compressed portions 51 is excessively intricate, the absorbent body 56 as a whole may lack flexibility or may feel as if a foreign object is mixed in the absorbent body 56 (foreign body sensation). Furthermore, if the dimensions of the highly compressed portions 51 are excessively small, if the shape of the highly compressed portions 51 is excessively long in one direction, or if the shape of the highly compressed portions 51 is excessively intricate, there is a problem in that the packaging sheet 58, when made of crepe paper, may be easily torn. Therefore, the diameter of the largest inscribed circle 53 inscribed in the outer shape of the highly compressed portions 51 is preferably 2 to 5 mm, and more preferably 2.5 to 3.5 mm. The circumferential length of the outer shape of the highly compressed portion 51 is preferably 1.0 to 2.5 times, more preferably 1.0 to 2.0 times, and particularly preferably 1.0 to 1.6 times the circumferential length of the largest inscribed circle 53 inscribed in the outer shape of the highly compressed portion 51.

[0070] As an example, the area of ​​each highly compressed portion 51 is 3 to 15 mm 2 The major axis d1 (the length of the long side of the smallest circumscribing rectangle) of each highly compressed portion 51 can be about 4 to 9 mm, and the minor axis d2 (the length of the short side of the smallest circumscribing rectangle) can be about 2 to 5 mm. When the lengths of the four sides of the smallest circumscribing rectangle of each highly compressed portion 51 are equal, the length d3 of the sides can be about 2 to 5 mm. The shortest distance d4 to the nearest other highly compressed portion 51 can be about 1.5 to 3.5 mm.

[0071] The external shape of the highly compressed portion 51 is not particularly limited, and is preferably a shape that does not have an inflection point or a bending point, such as a circle, an ellipse, or a rounded rectangle (including shapes in which one of the opposite sides is not a straight line but is a semicircle), but may also be a triangle, a rectangle, a cloud, an X-shape, a V-shape, a U-shape, etc.

[0072] Generally, when improving backflow prevention, the mixing ratio of high-absorbent polymer particles with high liquid retention is often increased. In recent years, the mixing ratio of high-absorbent polymer particles has also been increased in order to, for example, reduce the thickness of the absorbent body 56. However, increasing the mixing ratio of high-absorbent polymer particles not only reduces the shape retention of the highly compressed sections 51, but also makes it difficult for the absorbent body 56 to deform in the non-highly compressed sections 52 near the periphery of the highly compressed sections 51, as if pulled by the deformation of the highly compressed sections 51, which may make it difficult to improve backflow prevention and diffusion. Furthermore, the high-absorbent polymer particles that have absorbed and expanded excrement are likely to adhere to each other, which may inhibit the diffusion of excrement (gel blocking), which may make it difficult to improve diffusion. Therefore, the basis weight of the pulp fibers in the absorbent body 56 is set to 100 to 500 g / m 2 In this case, the weight ratio of pulp fibers to high-absorbent polymer particles in the absorbent body 56 is preferably 45:55 to 65:35.

[0073] The thickness 50t of the absorbent element 50 and the thickness 51t of the highly compressed portion 51 can be determined as appropriate, but insufficient compression may make it difficult to improve low return flow and diffusion. Therefore, when the above-mentioned range of pulp fiber basis weight and range of ratio of pulp fiber to superabsorbent polymer particles are adopted, the thickness 50t of the absorbent element 50 (thickness of the non-highly compressed portion 52) is preferably 5 to 13 mm. In this case, the thickness 51t of the highly compressed portion 51 (minimum value if the thickness varies) can be determined as appropriate, but is usually preferably 30 to 50% of the thickness 50t of the absorbent element 50.

[0074] The highly compressed portions 51 can be arranged in an appropriate regular or irregular pattern. For example, the highly compressed portions 51 can be arranged in a grid pattern in which the highly compressed portions 51 are arranged in a dotted line pattern as shown in Fig. 17, or in a staggered or matrix pattern in which the dotted highly compressed portions 51 are arranged as shown in Figs. 18 and 19. Although not shown, the highly compressed portions can also be arranged in a grid pattern in which linearly extending highly compressed portions are arranged.

[0075] One preferred pattern of the highly compressed portion 51 is the example shown in FIGS. In this example, in the arrangement region of the high compression sections 51, first virtual straight lines 81 along a first direction are repeatedly arranged at first intervals 81d in a second direction inclined 80 to 90 degrees clockwise relative to the first virtual straight line 81 in a planar view, and second virtual straight lines 82 along the second direction are repeatedly arranged at second intervals 82d in the first direction to define a virtual lattice. When a smallest virtual rectangle 83 having vertices at the intersections of the first virtual straight lines 81 and the second virtual straight lines 82 is defined, the high compression sections 51 are composed of first high compression sections 51a arranged at the intersections of the first virtual straight lines 81 and the second virtual straight lines 82, second high compression sections 51b arranged between adjacent first high compression sections 51a on the first virtual straight line 81 and between adjacent first high compression sections 51a on the second virtual straight line 82, and third high compression sections 51c arranged at the intersections of the diagonals of the virtual rectangle. Furthermore, the first highly compressed portions 51a are circular and have their centers at the intersections of the first and second imaginary lines 81 and 82, the second highly compressed portions 51b are rounded rectangles (or may be ovals) with centers of gravity at the midpoints of the sides of an imaginary rectangle and with major axes along the sides, and the third highly compressed portions 51c are rounded rectangles (or may be ovals or circles centered at the intersections of the diagonals of the imaginary rectangle) with centers of gravity at the intersections of the diagonals of the imaginary rectangle and with major axes along the front-to-rear direction LD. This pattern can improve the diffusibility of the second highly compressed portions 51b in the major axis directions (first and second directions), and since the non-highly compressed portions 52 have both a portion where they are linearly connected in the first direction and a portion where they are linearly connected in the second direction, even if each highly compressed portion 51 hardens, the absorber 56 as a whole will easily deform to fit the body surface.

[0076] 11 and 16, the dimensions of each highly compressed section 51 can be determined as appropriate, but the first highly compressed section 51a has a diameter of 1 to 4 mm, the second highly compressed section 51b has a major axis length of 3 to 6 mm and a minor axis length equal to the diameter of the first highly compressed section 51a, and the third highly compressed section 51c has the same size and shape as the second highly compressed section 51b except that its major axis is oriented along the front-to-rear direction LD. It is preferable that the shortest distance d4 between adjacent first and second highly compressed sections 51a and 51b is 1 to 2 mm, as this not only improves backflow prevention and liquid dispersibility but also improves ease of deformation of the absorbent body 56. The ratio of the first spacing 81d:second spacing 82d is preferably in the range of 0.9:1.1 to 1.1:0.9, and it is particularly preferable that the first spacing 81d and the second spacing 82d are equal. The first gap 81d and the second gap 82d can be set to about 10 to 14 mm.

[0077] Furthermore, if the above-mentioned virtual grid is formed in a diagonal grid pattern in which the first virtual straight line 81 is inclined 40 to 50 degrees clockwise relative to the front-to-back direction LD in a planar view and the second virtual straight line 82 is inclined 40 to 50 degrees counterclockwise relative to the front-to-back direction LD in a planar view, this is preferable because it not only improves the ease of deformation of the absorbent body 56 when worn, but also provides excellent liquid diffusion properties.

[0078] The absorbent element can be manufactured by a known method. For example, an absorbent element 50 having highly compressed portions 51 can be manufactured by carrying out the following steps: a first step of forming an absorbent body 56 by mixing and accumulating pulp fibers and superabsorbent polymer particles; a second step of forming a package 50P by wrapping the entire absorbent body 56 in a package sheet 58; and a third step of passing the package 50P between an anvil roll 90 having numerous protrusions 91 arranged at intervals on its outer circumferential surface in the same pattern as the highly compressed portions 51 and a smooth roll 92 having a cylindrical surface (without protrusions 91) facing the anvil roll 90, as shown in Fig. 22 , and pressing the portions of the package 50P sandwiched between the numerous protrusions 91 of the anvil roll 90 and the smooth roll 92 to form the highly compressed portions 51. The highly compressed portions 51 may be formed while heating either the anvil roll 90 or the smooth roll 92, or without heating. In the third step, only the portion of the packaging body 50P that is sandwiched between the numerous protrusions 91 of the anvil roll 90 and the smooth roll 92 may be pressed, or the entire packaging body 50P may be pressed while the portion that is sandwiched between the numerous protrusions 91 of the anvil roll 90 and the smooth roll 92 is pressed to the deepest extent.

[0079] The dimensions, shape, and arrangement of the tip surfaces of the protrusions 91 can be, for example, the same as the dimensions, shape, and arrangement of the highly compressed portions 51. The clearance (minimum distance between the pressing positions) between the anvil roll 90 and the smooth roll 92 can be equal to or less than the thickness of the highly compressed portions 51, and can be, for example, 0.5 to 1.5 mm. The pressure applied when the highly compressed portions 51 are formed by the anvil roll 90 and the smooth roll 92 can be determined as appropriate, and can be, for example, 0.2 to 0.4 MPa.

[0080] (packaging sheet) The packaging sheet 58 can be made of crepe paper, nonwoven fabric, polylaminated nonwoven fabric, perforated sheet, etc. The nonwoven fabric used for the packaging sheet 58 is not particularly limited, but SMS nonwoven fabric, SSMMS nonwoven fabric, etc., in which at least one meltblown layer is sandwiched between a pair of spunbond layers on the front and back, can be suitably used. The material of the fiber is not particularly limited, and for example, polypropylene fiber, polyethylene / polypropylene bicomponent fiber, etc. can be used. The basis weight of the packaging sheet 58 can be determined as appropriate, but is preferably 5 to 40 g / m 2 , especially 10 to 30 g / m 2 It is preferable that:

[0081] The crepe paper used for the packaging sheet is not particularly limited, but the basis weight is 13 to 20 g / m 2 , especially 14-18g / m 2 Furthermore, the air permeability of the crepe paper measured in accordance with JIS P 8117:2009 "Paper and paperboard - Air permeability and air resistance test method (intermediate range) - Gurley method" is preferably 1 to 15 seconds.

[0082] On the other hand, the crepe paper used for packaging sheet 58 generally has a tensile breaking elongation of 20 to 35% in the front-to-rear direction LD and 4 to 8% (particularly 5 to 7%) in the width direction WD as specified in JIS P 8113:2006. When packaging sheet 58 is made of such crepe paper, the crepe paper may tear at the edges of highly compressed sections 51 or between adjacent highly compressed sections 51 when forming them. However, this can be reduced by ensuring that the outer shape of highly compressed sections 51 does not have an inflection point or bending point, that the diameter of the largest inscribed circle inscribed in the outer shape of highly compressed sections 51 is 2 to 5 mm, and that the perimeter of the outer shape of highly compressed sections 51 is 1 to 2.5 times the perimeter of the largest inscribed circle inscribed in the outer shape of highly compressed sections 51.

[0083] It is preferable for the packaging sheet 58 to be configured so that the MD direction is aligned with the front-to-rear direction LD, as this facilitates manufacturing. In this case, the fiber orientation of the packaging sheet 58 is in the front-to-rear direction LD, and the dry tensile strength in the width direction WD is significantly weaker than the dry tensile strength in the front-to-rear direction LD. Therefore, if the dimension of the highly compressed portion 51 in the front-to-rear direction LD is more than twice, particularly more than three times, the dimension of the highly compressed portion 51 in the width direction WD (i.e., the highly compressed portion 51 is elongated in the front-to-rear direction LD), the packaging sheet 58 is likely to tear on both sides of the width direction WD. Therefore, it is preferable for the dimension of the highly compressed portion 51 in the front-to-rear direction LD to be less than twice, particularly less than 1.5 times, the dimension of the highly compressed portion 51 in the width direction WD, as this makes the packaging sheet 58 less likely to tear.

[0084] The packaging structure of the packaging sheet 58 can be determined as appropriate, but from the standpoint of ease of manufacturing and preventing leakage of superabsorbent polymer particles from the front and rear edges, it is preferable to wrap the sheet around the absorbent body 56 in a cylindrical shape so as to surround the front, back, and both side surfaces, as shown in the illustrated example, with the front and rear edges extending beyond the front and rear of the absorbent body 56, and to join the overlapping wound portions and the overlapping portions of the extending front and rear edges by a joining means such as a hot melt adhesive or material welding.

[0085] In particular, as shown in Figure 15, the packaging sheet 58 has a surface portion 58s located on the front side of the absorbent body 56, a first back side portion 58a that continues from the surface portion 58s and wraps around one side edge of the absorbent body 56 to reach the back side of the absorbent body 56, and a second back side portion 58b that continues from the surface portion 58s and wraps around the other side edge of the absorbent body 56 to reach the back side of the absorbent body 56, and the first back side portion 58a and the second back side portion 58b have a stacked portion 58W in which they overlap each other, and it is preferable that all the highly compressed portions 51 are formed in the stacked portion 58W, as this doubles the crepe paper on the forming surface of the highly compressed portions 51, improving strength and making them less likely to tear when the highly compressed portions 51 are formed.

[0086] The shape retention of the absorbent element 50 due to the highly compressed portions 51 is determined by the retention of the highly compressed portions 51 themselves, which in turn is determined by the bond strength between the packaging sheet 58 and the absorbent body 56 in the highly compressed portions 51 and the shape retention of the absorbent body 56 itself. When the packaging sheet 58 and the absorbent body 56 are bonded together using hot melt adhesives HM1 and HM2, the increase in surface area due to the formation of the highly compressed portions 51 requires more hot melt adhesive HM1 and HM2 than usual to sufficiently maintain the bond strength between the packaging sheet 58 and the absorbent body 56 and the shape retention of the absorbent body 56 itself. Therefore, the surface of the absorbent body 56 and the inner surface of the packaging sheet 58 should have a density of 5.0 to 20.0 g / m2 at least over the entire region having the highly compressed portions. 2 , especially 7.5 to 15.0 g / m 2 It is preferable that the adhesive is bonded via the hot melt adhesives HM1 and HM2.

[0087] For example, as shown in Figure 9, when a depression is formed on the surface of the absorbent body 56 due to the highly compressed portion 51, the above-mentioned amount of hot melt adhesive HM can be achieved by providing two layers of hot melt adhesive HM1, HM2 on the back surface of the absorbent body 56 over the entire area having the highly compressed portion 51. As shown in FIG. 13, such a structure can be produced by applying a first hot melt adhesive HM1 to almost the entire inner surface of an unfolded packaging sheet 58 facing the absorbent body 56, then placing the absorbent body 56 in the middle of the first hot melt adhesive HM1 in the width direction WD of the packaging sheet 58 and bonding the back surface of the absorbent body 56 to the packaging sheet 58 via the first hot melt adhesive HM1, then applying a second hot melt adhesive HM2 to almost the entire surface of the absorbent body 56, and then, as shown in FIG. 14, folding back the portions of the packaging sheet 58 that are protruding on both sides of the absorbent body 56 onto the surface of the absorbent body 56, respectively, bonding the surface of the absorbent body 56 to the folded-back portions of the packaging sheet 58 via the first hot melt adhesive HM1 and the second hot melt adhesive HM2, and bonding the overlapping portions of the packaging sheet 58 via the first hot melt adhesive HM1, and then forming a lattice-shaped highly compressed portion 51 by embossing, as shown in FIG. 9.

[0088] In order to reduce costs, the absorbent element 50 may have no other sheet layers such as paper or nonwoven fabric (which may of course have an adhesive layer) between the packaging sheet 58 and the absorbent body 56, as shown in Figure 9, or may have other sheet layers on at least one side of the front or back of the absorbent body 56.

[0089] (Get up and gather) The rising gathers 60 have rising portions 68 that rise from the sides of the inner body 200, and these rising portions 68 come into contact with the wearer's area from the groin through the legs to the buttocks, preventing side leakage. The rising gathers 60 can be omitted as necessary. In the illustrated example, the rising gathers 60 have a base side portion 60B that rises obliquely toward the center in the width direction, and a portion 60A from the middle portion to the tip side that rises obliquely toward the outside in the width direction, but the present invention is not limited to this and can be modified as appropriate, such as one that rises toward the center in the width direction as a whole.

[0090] More specifically, the rising gathers 60 in the illustrated example are formed by folding a strip-shaped gathered sheet 62, having a length equal to the longitudinal length of the inner body 200, in two by folding back the leading end in the width direction WD, and by fixing a plurality of elongated gathered elastic members 63 between the folded-back portion and the sheet in the vicinity thereof in a stretched state along the longitudinal direction at intervals in the width direction WD. A base end portion of the rising gathers 60 opposite the leading end (the end portion opposite the folded-back portion of the sheet in the width direction WD) serves as a root portion 65 fixed to the side portion of the inner body 200, and the portion other than the root portion 65 serves as a main body portion 66 (the portion on the folded-back portion side) extending from the root portion 65. The main body portion 66 further has a root portion 60B extending toward the center in the width direction and a tip portion 60A folded back at the leading end of the root portion 60B and extending outward in the width direction. The front-to-rear end portions of the main body portion 66 are formed as fallen portions 67 which are fixed in a fallen state to the side surfaces of the top sheet 30, while the front-to-rear intermediate portion between them is formed as an unfixed raised portion 68, and a gathered elastic member 63 extending along the front-to-rear direction LD is fixed in a stretched state to at least the tip portion of this raised portion 68.

[0091] In the rising gathers 60 configured as described above, the contractile force of the gather elastic member 63 causes the rising portions 68 to rise up so as to come into contact with the skin as shown by the arrows in Fig. 3. In particular, when the base portion 65 is located on the back side of the inner body 200, the rising portions 68 rise up so as to open outward in the width direction in the crotch region and its vicinity, so that the rising gathers 60 come into contact with the surrounding legs with a full surface, improving fit. The base portion 65 can also be fixed to the front side of the inner body 200, for example, to the surfaces of both side portions of the top sheet 30.

[0092] In a bent structure such as the illustrated example of the rising gathers 60, in which the main body portion 66 is composed of a base portion 60B extending toward the center in the width direction and a tip portion 60A folded back at the tip of the base portion 60B and extending outward in the width direction, the tip portion 60A and the base portion 60B are joined in a folded state at the fallen portion 67, and the base portion 60B is joined in a folded state to the topsheet 30. To join the opposing surfaces at the fallen portion 67, at least one of various application methods of hot melt adhesive and material welding means such as heat sealing and ultrasonic sealing can be used. In this case, the joining of the base portion 60B and the topsheet 30 and the joining of the tip portion 60A and the base portion 60B may be performed by the same means or by different means. For example, it is preferable to join the root side portion 60B and the top sheet 30 with a hot melt adhesive, and to join the tip side portion 60A and the root side portion 60B with material welding.

[0093] As the gathered sheet 62, a nonwoven fabric that is soft and has excellent uniformity and hiding power, such as a spunbond nonwoven fabric (SS, SSS, etc.), an SMS nonwoven fabric (SMS, SSMMS, etc.), or a meltblown nonwoven fabric, and that has been subjected to a water-repellent treatment with silicone or the like as necessary, can be suitably used. In this case, the fiber weight of the nonwoven fabric is 10 to 30 g / m 2 Although not shown, a waterproof film can be interposed between the two folded gathered sheets 62.

[0094] The gathered elastic members 63 can be made of rubber thread or the like. When spandex rubber thread is used, the thickness is preferably 470 to 1240 dtex, more preferably 620 to 940 dtex. The elongation percentage of the gathered elastic members 63 in the attached state is preferably 150 to 350%, more preferably 200 to 300%. The number of gathered elastic members 63 is preferably 2 to 6, more preferably 3 to 5. The appropriate spacing between the gathered elastic members 63 is 3 to 10 mm. With this configuration, the gathered elastic members 63 can easily contact the skin over their entire surface within the range where they are arranged. The gathered elastic members 63 may be arranged not only on the tip side but also on the base side.

[0095] In the rising portion 68 of the rising gathers 60, at least one of various application methods of hot melt adhesive and material welding, such as heat sealing or ultrasonic sealing, can be used to bond the inner and outer layers of the gathered sheet 62 together and to secure the gathered elastic member 63 sandwiched therebetween. Since bonding the entire inner and outer layers of the gathered sheet 62 together reduces flexibility, it is preferable to leave the areas other than the adhesive portion of the gathered elastic member 63 unbonded or to only weakly bond them. In the illustrated example, hot melt adhesive is applied only to the outer peripheral surface of the gathered elastic member 63 using an application means such as a comb gun or a SureWrap nozzle, and the gathered elastic member 63 is sandwiched between the inner and outer layers of the gathered sheet 62. This results in a structure in which the gathered elastic member 63 is secured to the inner and outer layers of the gathered sheet 62 and the inner and outer layers of the gathered sheet 62 are secured together solely by the hot melt adhesive applied to the outer peripheral surface of the gathered elastic member 63.

[0096] Similarly, the fallen portion 67 can be fixed by at least one of various application methods of hot melt adhesive and material welding such as heat sealing or ultrasonic sealing.

[0097] (Side flap) 1 to 4, etc., side flaps 70 extending out to the sides of the absorbent body 56 are provided on both sides of the inner body 200, and it is preferable that side stretchable regions SG that stretch in the front-to-rear direction are formed in these side flaps 70. The side flaps 70 in the illustrated example have one or more elongated side elastic members 73 arranged along the front-to-rear direction LD and spaced apart from one another, a first sheet layer 71 facing the outside of the side elastic member 73, and a second sheet layer 72 facing the inside of the side elastic member 73.

[0098] The sheet material forming the first sheet layer 71 and the second sheet layer 72 is not particularly limited, and any suitable nonwoven fabric can be selected, such as the nonwoven fabric that can be used for the above-mentioned rising gathers 60 and the above-mentioned outer bodies 12F, 12B. In the illustrated example, the first sheet layer 71 and the second sheet layer 72 are formed by extending the gathered sheet 62 of the rising gathers 60, as will be described later. In this case, the front and rear ends of the side flaps 70 coincide with the front and rear ends of the rising gathers 60 (i.e., the front and rear ends of the inner body 200 in this case).

[0099] The side elastic members 73 are not particularly limited, and can be elongated elastic members similar to the gathered elastic members 63 described above. The extension percentage of the side elastic members 73 in the attached state is preferably 150 to 350%, more preferably 200 to 270%. The number of side elastic members 73 is preferably 2 to 16, more preferably 6 to 10. The appropriate spacing between the side elastic members 73 is 5 to 10 mm.

[0100] The side elastic members 73 are fixed to the first sheet layer 71 and the second sheet layer 72. Various application methods of hot melt adhesive HM or material welding methods such as heat sealing and ultrasonic sealing can be used to bond the first sheet layer 71 and the second sheet layer 72 together and to secure the side elastic members 73 sandwiched between them. Because a large bonded area between the first sheet layer 71 and the second sheet layer 72 reduces flexibility, it is preferable to leave the portions of the side elastic members 73 unbonded or to only weakly bond them. In the illustrated example, the hot melt adhesive HM is applied only to the outer peripheral surfaces of the side elastic members 73 using an application method such as a comb gun or a SureWrap nozzle, and then the side elastic members 73 are sandwiched between the first sheet layer 71 and the second sheet layer 72. The hot melt adhesive HM applied only to the outer peripheral surfaces of the side elastic members 73 secures the side elastic members 73 to the first sheet layer 71 and the second sheet layer 72 and secures the first sheet layer 71 and the second sheet layer 72 together.

[0101] In the illustrated example, the sheet material constituting the first sheet layer 71 and the sheet material constituting the second sheet layer 72 are folded back at the side edges of the side flaps 70, and these folded back portions are fixed (the bag is closed) to the back surface of the liquid-impermeable sheet 11. This fixing can be performed with a hot melt adhesive HM as in the illustrated example, or by welding the materials.

[0102] The side flaps 70 may be omitted.

[0103] <Effectiveness Confirmation Test 1> Samples of the absorbent element were prepared under the various conditions shown in Table 1, and were subjected to an evaluation of the tearing of the packaging sheet, a diffusion behavior confirmation test, a non-pressurized return test, a pressurized return test, and an absorption speed test. The basis weight of the packaging sheet, the dry tensile strength of the packaging sheet, and the tensile breaking elongation of the packaging sheet in Tables 1 and 3 are High compression section This is a measurement of the material before it is formed.

[0104] The dimensions of each part of Sample 1 were as follows: Length d3 of the first highly compressed portion 51a: 3 mm Major diameter d1 of the second and third highly compressed sections: 4.82 mm Minor diameter d2 of the second and third highly compressed sections: 3 mm First distance 81d: 12.63mm Second spacing 82d: 12.63mm Intersection angle between the first imaginary line 81 and the second imaginary line 82: 90 degrees

[0105] The dimensions of each part of Sample 1 were as follows: Length d3 of the first highly compressed portion 51a: 2 mm Major diameter d1 of the second and third highly compressed sections: 3.82 mm Minor diameter d2 of the second and third highly compressed sections: 2 mm First distance 81d: 12.63mm Second spacing 82d: 12.63mm Intersection angle between the first imaginary line 81 and the second imaginary line 82: 90 degrees

[0106] In Samples 1 to 7, the highly compressed portions were formed over the entire surface of the absorbent element at a pressure of 0.4 MPa. Sample 8 was a comparative example that did not have a highly compressed portion. Conditions other than the specifications shown in Table 1 were the same for all samples.

[0107] (Evaluation of packaging sheet tearing) The surface of the absorbent element sample was visually observed, and if tears occurred in the same position relative to the highly compressed portion over almost the entire surface of the absorbent element, it was rated as ×; if small tears occurred in part of the surface of the absorbent element but no tears occurred over most of the surface, it was rated as △; and if no tears occurred at all, it was rated as ◯.

[0108] (Diffusion behavior confirmation test) This test was carried out according to the following procedure. (1) The sample was placed on a horizontally placed flat plate with the surface (the surface with the depression in the highly compressed area) facing up, and the four corners of the sample in the unfolded state were fixed to the flat plate with adhesive tape. (2) Approximately 5 g of Kiriya Co.'s Brilliant Blue FCF (packaged as powder) was dissolved in approximately 300 ml of artificial urine to prepare a blue test solution. (3) Place a casting tube (an acrylic cylinder with an inner diameter of 23 mm, an outer diameter of 25 mm, and a height of 100 mm) at the center of the sample surface (the center in the width direction and the center in the front-to-back direction) and hold it vertically. Using a measuring cylinder, pour 1.5 cm of the blue test liquid into the top opening of the casting tube. 3 was injected at once. (4) After 5 minutes, the injection tube was removed and still images of the front and back surfaces of the sample were taken. The captured image data was read into image analysis software, and the area of ​​the blue parts on the front and back surfaces of the sample was measured.

[0109] (Absorption rate test) This test was carried out according to the following procedure. (1) The sample was placed on a horizontally placed flat plate with the surface (the surface with the depression in the highly compressed area) facing up, and the four corners of the sample in the unfolded state were fixed to the flat plate with adhesive tape. (2) An injection tube (an acrylic cylinder with an inner diameter of 3 mm, an outer diameter of 6 mm, and a height of 220 mm) was held vertically above the center of the sample surface (the center in the width direction and the center in the front-to-back direction), and the distance between the bottom end of the injection tube and the sample surface was 10 mm. (3) Using a measuring cylinder, add 70 cm of the above blue test solution to the top opening of the injection tube. 3 7cm 3 The time (in seconds) from the start of injection until the artificial urine disappeared from the surface of the sample (complete absorption) was measured using a stopwatch, and this time was regarded as the first absorption rate. Whether or not the artificial urine was completely absorbed was determined by visual observation by the operator. (4) After leaving it for 30 minutes, the above procedure (3) was repeated and the absorption rate was measured for the second time.

[0110] (Non-pressurized reversal test) This test was carried out according to the following procedure. (1) The sample was placed on a horizontally placed flat plate with the surface (the surface with the depression in the highly compressed area) facing up, and the four corners of the sample in the unfolded state were fixed to the flat plate with adhesive tape. (2) An injection tube (an acrylic cylinder with an inner diameter of 23 mm, an outer diameter of 25 mm, and a height of 100 mm) was placed at the center of the sample surface (the center in the width direction and the center in the front-to-back direction) and held vertically. (3) Using a measuring cylinder, add 50 cm of the above blue test solution to the top opening of the injection tube. 3 7cm 3 The artificial urine was injected at a rate of 1 / sec, and the test was continued from the start of injection until the artificial urine disappeared from the sample surface (was completely absorbed). (4) The weight (g) of 10 sheets of ADVANTEC's qualitative filter paper No. 2 (100mm x 100mm square) was measured to three decimal places using an electronic balance. (5) 30 minutes after the artificial urine injected in (3) above had been completely absorbed, 10 sheets of the above filter paper were placed face-to-face on top of each other at the point where the artificial urine had been injected, and a 1 kg weight was placed on top of them and left. The weight had a square shape with a flat bottom, measuring 100 mm long and 100 mm wide. The filter paper and weight were placed on the sample surface so that the length and width of the filter paper and weight were aligned with the front-to-back and width directions of the sample, and so that the centers of the filter paper and weight were located at the center of the sample surface. (6) One minute after placing the weight (5) above, all the filter papers were removed and their weights (g) were measured to two decimal places. The measured weights after absorption were subtracted from the measured weights before absorption (4) above to determine the amount of backflow under no pressure.

[0111] (Reverse test under pressure) This test was carried out according to the following procedure. (1) The sample was placed on a horizontally placed flat plate with the surface (the surface with the depression in the highly compressed area) facing up, and the four corners of the sample in the unfolded state were fixed to the flat plate with adhesive tape. (2) An injection tube (an acrylic cylinder with an inner diameter of 23 mm, an outer diameter of 25 mm, and a height of 100 mm) was placed at the center of the sample surface (the center in the width direction and the center in the front-to-back direction) and held vertically. (3) Using a measuring cylinder, add 50 cm of the above blue test solution to the top opening of the injection tube.3 7cm 3 / sec., and wait until the artificial urine disappears from the surface of the sample (is completely absorbed). After 30 minutes, pour 50cm of the blue test liquid into the top opening of the injection tube using a measuring cylinder. 3 7cm 3 was injected at a rate of 1000 / sec. (4) Twenty minutes after the second injection of artificial urine was completely absorbed, a 3 kg weight was placed on the injection site and left for 10 minutes. The weight was a square with a flat base measuring 100 mm long and 100 mm wide, and was placed on the sample surface so that the length and width of the weight were aligned with the front-to-back and width directions of the sample, and the center of the weight was located at the center of the sample surface. (5) The weight (g) of 30 sheets of ADVANTEC's qualitative filter paper No. 2 (100mm x 100mm square) was measured to three decimal places using an electronic balance. (6) After (4) above, 30 sheets of the above filter paper were placed between the weight and the sample surface with the center and orientation aligned, and after 20 seconds, all the filter papers were removed and their weight (g) was measured to two decimal places. The measured weight after absorption was subtracted from the measured weight before absorption in (5) above to determine the amount of return under pressure.

[0112] [Table 1]

[0113] The test results are shown in Table 2.

[0114] [Table 2]

[0115] Like Samples 3 to 7, Samples 1 and 2 not only had superior diffusion properties (sufficiently large diffusion area) compared to Sample 8, but also had smaller amounts of return under pressure and return under pressure compared to Samples 3 to 8. Also, like Samples 3 to 6, Samples 1 and 2 had superior absorption speed compared to Samples 7 and 8. Furthermore, Samples 1 and 2 were also superior in terms of crepe paper tear resistance.

[0116] <Effectiveness Confirmation Test 2> The various absorbent elements shown in Table 3 were used to prepare pants-type disposable diaper samples shown in Figures 1 to 6, and the above-mentioned non-pressure return test, pressure return test, and absorption rate test were conducted. The dimensions and arrangement of each part of the highly compressed part of Sample 9 were the same as those of Sample 1. Samples 10 and 11 were comparative examples that did not have a highly compressed part. Conditions other than those shown in Table 3 were the same for all samples.

[0117] [Table 3]

[0118] The test results are shown in Table 4.

[0119] [Table 4]

[0120] This test on diaper samples also showed the same tendency as in Effect Confirmation Test 1, which measured only the absorbent element. That is, compared to samples 10 and 11, sample 9 had less backflow under pressure and less backflow under pressure, and also had a superior absorption rate.

[0121] <Explanation of terms used in the specification> In the present specification, the following terms have the following meanings unless otherwise specified in the specification.

[0122] "Front-rear direction" refers to the direction indicated by the symbol LD in the drawing (longitudinal direction), and "width direction" refers to the direction indicated by the symbol WD in the drawing (left-right direction), with the front-rear direction and width direction being perpendicular to each other.

[0123] "Front side" means the side closest to the wearer's skin when worn, and "reverse side" means the side farthest from the wearer's skin when worn.

[0124] "Front" means the side closest to the wearer's skin when worn, and "back" means the side away from the wearer's skin when worn.

[0125] "Elongation rate" refers to the value when the natural length is 100%. For example, an elongation rate of 200% is equivalent to an elongation ratio of 2 times.

[0126] "Artificial urine" is a mixture of 2 wt% urea, 0.8 wt% sodium chloride, 0.03 wt% calcium chloride dihydrate, 0.08 wt% magnesium sulfate heptahydrate, and 97.09 wt% ion-exchanged water.

[0127] "Gel strength" is measured as follows: 1.0 g of superabsorbent polymer is added to 49.0 g of artificial urine and stirred with a stirrer. The resulting gel is left in a constant temperature and humidity chamber at 40°C and 60% RH for 3 hours, then returned to room temperature, and the gel strength is measured using a card meter (I.techno Engineering: Curdmeter-MAX ME-500).

[0128] "Basis weight" is measured as follows: After pre-drying the sample or test piece, leave it in a test room or device under standard conditions (test location: temperature 23±1°C, relative humidity 50±2%) until it reaches a constant weight. Pre-drying refers to bringing the sample or test piece to a constant weight in an environment at a temperature of 100°C. Note that pre-drying is not necessary for fibers with an official moisture regain of 0.0%. From the test piece that has reached a constant weight, use a sample collection template (100mm x 100mm) to cut out a sample measuring 100mm x 100mm. Measure the weight of the sample and multiply it by 100 to calculate the weight per square meter, which is the basis weight.

[0129] The "thickness" of thick members such as the absorber 56 and the absorbent element 50 is measured using a thickness gauge (Peacock, Dial Thickness Gauge, Model H (measurement range: 0 to 10 mm, probe: circular pressure plane with a diameter of 10 mm, measurement force: approximately 1.7 N, pressure: approximately 21.7 KPa)) manufactured by Ozaki Seisakusho Co., Ltd., with the test member and the thickness gauge positioned horizontally. The thickness of the absorbent element 50 (non-highly compressed portion 52) is determined as follows: That is, ten regions of the non-highly compressed portion 52 of the absorbent element 50 where the inscribed circle inscribed in the outer shape of the non-highly compressed portion 52 is selected, and the thickness measured by aligning the center of the inscribed circle of each region with the center of the probe of the thickness gauge is defined as the thickness of the absorbent element 50 (non-highly compressed portion 52).

[0130] The "thickness" of the highly compressed portion 51 is calculated by subtracting the depth of the highly compressed portion 51 from the thickness of the absorbent element 50 (non-highly compressed portion 52).

[0131] The "depth" of the highly compressed portion 51 is measured using a Keyence Corporation one-shot 3D measuring macroscope VR-3200 or equivalent and image analysis software "VR-H2A" or equivalent. As a rule, the measurement is performed at a magnification of 12x and a field of view of 24mm x 18mm, but the magnification and field of view can be changed depending on the size of the highly compressed portion 51. The specific measurement procedure is described below with reference to Figure 23. That is, using the software, a depth (measured cross-sectional curve) profile is obtained along a line segment Q1 passing through the center (or center of gravity, if the shape is not circular) of one highly compressed portion 51 in the image area (XY area in the figure) shown from a planar perspective. The cross-sectional curve of this embossing depth profile is filtered using a low-pass filter to remove surface roughness components with wavelengths shorter than λc:800 μm (where λc is the "filter defining the boundary between roughness and waviness components" as described in JIS-B0601, section 3.1.1.2). The image portion (XZ portion in the figure) shown from a cross-sectional perspective is then filtered to obtain a "contour curve Q2." Two boundary points P1 and P2 are defined as the positions where the curve is nearly flat or where the curve is most pronounced upward. The minimum height of the range between these boundary points P1 and P2 is then calculated. Furthermore, the average of the height values ​​of boundary points P1 and P2 is defined as the maximum height. The depth of the highly compressed portion 51 can then be calculated by subtracting the minimum height from the maximum height. The two boundary points P1 and P2 are visually selected. The planar image of the highly compressed portion 51 being measured may be used as a reference for this selection. The above measurement is carried out for any 10 highly compressed portions 51 on the surface, and the results are taken as the average value.

[0132] The "thickness" of thin sheets such as nonwoven fabrics was measured using an automatic thickness measuring device (KES-G5 handy compression measurement program) with a load of 0.098 N / cm 2 , and pressure area: 2cm 2 Automatic measurement is performed under the following conditions.

[0133] "Area ratio" means the proportion of the area of ​​the target portion per unit area, and is expressed as a percentage by dividing the total area of ​​the target portion (e.g., the highly compressed portion 51) in the entire target region (e.g., the back surface of the absorbent element 50) by the area of ​​the target region. The dimensions, area, etc. of the highly compressed portion 51 are measured by taking a still image of the surface of the absorbent element 50 having the highly compressed portion 51, and reading the captured image data into image analysis software. At this time, the measurement target portion of the highly compressed portion 51 is automatically selected based on shading, or if automatic selection is not possible, selected visually.

[0134] "Water absorption" is measured according to JIS K7223-1996 "Test method for water absorption of superabsorbent polymers."

[0135] "Water absorption rate" is the "time to the end point" when 2g of superabsorbent polymer and 50g of physiological saline are used and the test is carried out in accordance with JIS K7224-1996 "Test method for water absorption rate of superabsorbent polymers."

[0136] "Deployed state" means a flat, deployed state without contraction (including any contraction, such as contraction due to elastic members) or slack.

[0137] Unless otherwise specified, the dimensions of each part refer to the dimensions in the unfolded state, not in the natural length state.

[0138] If no environmental conditions are specified for a test or measurement, the test or measurement shall be carried out in a test room or device under standard conditions (temperature 23±1°C, relative humidity 50±2%). [Industrial Applicability]

[0139] The present invention can be used for all absorbent articles that have a crotch area (preferably also have a portion extending from the crotch area to either or both the front and back sides), including disposable diapers such as pants-type disposable diapers, tape-type disposable diapers, and pad-type disposable diapers, as well as sanitary napkins. [Explanation of symbols]

[0140] 11...liquid-impermeable sheet, 12A...side seal, 12B...rear outer body, 12E...waist extension portion, 12F, 12B...outer body, 12F...front outer body, 12S, 12H...sheet material, 13...cover nonwoven fabric, 16, 19...waist lower elastic member, 17...waist elastic member, 18...unnecessary elastic member, 20...inner body joint portion, 200...inner body, 30...top sheet, 40...intermediate sheet, 50...absorbent element, 50P...packaging body, 51...highly compressed portion, 51a...first highly compressed portion, 51b...second highly compressed portion, 51c...third highly compressed portion, 52...non-highly compressed portion, 56...absorbent body, 56L...low basis weight portion, 58...packaging sheet, 60...rising gathers, 60A...tip side portion, 60B...base side portion, 62...gathers sheet, 63...gathered elastic member, 67...folded portion, 68...risen portion, 70...side flap, 71...first sheet layer, 72...second sheet layer, 73...side elastic member, 81...first imaginary straight line, 82...second imaginary straight line, 90...anvil roll, 91...projection portion, 92...smooth roll, A1...non-stretchable region, A2...stretchable region, B...back body, C...buttocks covering portion, F...front body, HM...hot melt adhesive, HM1...first hot melt adhesive, HM2...second hot melt adhesive, L...middle region, LD...front and rear direction, LO...leg opening, M...crotch portion, SG...side stretchable region, T...torso region, TD...thickness direction, U...lower waist portion, W...waist portion, WD...width direction, WO...waist opening.

Claims

1. It has a crotch area, an absorbent element including an absorbent body provided in a front-rear direction range including the crotch area and a packaging sheet that wraps the absorbent body; The absorbent body is made by mixing and accumulating pulp fibers and superabsorbent polymer particles, the pulp fiber weight in the absorbent body is 100 to 500 g / m 2 ; the weight ratio of pulp fibers to superabsorbent polymer particles in the absorbent body is 45:55 to 65:35; The packaging sheet is crepe paper having a tensile breaking elongation in the front-rear direction of 20 to 35% and a tensile breaking elongation in the width direction (WD) of 4 to 8%, as specified in JIS P 8113:2006; The absorbent element has highly compressed portions compressed in the thickness direction so as to be recessed from the surface of the absorbent element to the inside of the absorbent body, the highly compressed portions being arranged at intervals, In the arrangement region of the highly compressed portions, first virtual straight lines along a first direction are repeatedly arranged at first intervals in a second direction inclined by 80 to 90 degrees clockwise in a plan view with respect to the first virtual straight lines, and second virtual straight lines along the second direction are repeatedly arranged at second intervals in the first direction to define a virtual lattice; When the smallest imaginary rectangle having vertices at the intersections of the first imaginary line and the second imaginary line is defined, the high-compression portion includes a first high-compression portion disposed at an intersection of the first imaginary line and the second imaginary line, a second high-compression portion disposed between adjacent first high-compression portions on the first imaginary line and between adjacent first high-compression portions on the second imaginary line, and a third high-compression portion disposed at an intersection of diagonals of the imaginary rectangle, the first highly compressed portion has a circular shape centered at the intersection of the first virtual line and the second virtual line, the second highly compressed portion is an ellipse or a rounded rectangle having a center of gravity at the midpoint of each side of the imaginary rectangle and having a major axis along each side, the third highly compressed portion has a center of gravity at an intersection of diagonals of the imaginary rectangle and is an ellipse or a rounded rectangle having a long axis along the front-rear direction, or a circle having a center at the intersection of diagonals of the imaginary rectangle, a portion other than the highly compressed portions in the arrangement region of the highly compressed portions is a non-highly compressed portion that is thicker and has a lower density than the highly compressed portions, the thickness of the highly compressed portion is 30 to 50% of the thickness of the non-highly compressed portion; the diameter of the largest inscribed circle inscribed in the outer shape of the highly compressed portion is 2 to 5 mm, and the circumferential length of the outer shape of the highly compressed portion is 1 to 2 times the circumferential length of the largest inscribed circle inscribed in the outer shape of the highly compressed portion, an area ratio of the highly compressed portions in the arrangement region of the highly compressed portions is greater than 25.4% and not more than 35%; The diameter of the largest inscribed circle inscribed in the outer shape of the non-highly compressed portion is 6.5 mm or less. An absorbent article characterized by:

2. The thickness of the non-highly compressed portion is 5 to 13 mm. The absorbent article of claim 1.

3. the first highly compressed portion has a diameter of 1 to 4 mm; the second highly compressed portion has a major axis length of 3 to 6 mm and a minor axis length equal to the diameter of the first highly compressed portion; the third highly compressed portion has the same size and shape as the second highly compressed portion except that the direction of the major axis is along the front-rear direction, The minimum distance between the adjacent first highly compressed portion and the adjacent second highly compressed portion is 1 to 2 mm. The absorbent article according to claim 1 or 2.

4. The virtual grid has an oblique grid shape in which the first virtual straight line is inclined by 40 to 50 degrees clockwise with respect to the front-to-rear direction in a plan view, and the second virtual straight line is inclined by 40 to 50 degrees counterclockwise with respect to the front-to-rear direction in a plan view. The absorbent article according to claim 1 or 2.

5. A method for manufacturing an absorbent element having an absorbent body formed by mixing and accumulating pulp fibers and superabsorbent polymer particles, and a packaging sheet for wrapping the absorbent body, comprising: a first step of mixing and collecting the pulp fibers and the superabsorbent polymer particles to form an absorbent body having a pulp fiber:superabsorbent polymer particle weight ratio of 45:55 to 65:35 and a basis weight of the pulp fibers of 100 to 500 g / m 2; a second step of forming a package by wrapping the entire absorbent body in a wrapping sheet made of crepe paper having a tensile breaking elongation of 20 to 35% in the front-rear direction and a tensile breaking elongation of 4 to 8% in the width direction (WD) as specified in JIS P 8113:2006; a third step of sandwiching the package between an anvil roll having projections arranged at intervals on its outer circumferential surface and a smooth roll facing the anvil roll and having a cylindrical surface, and pressing the portion of the package sandwiched between the numerous projections of the anvil roll and the smooth roll so as to be recessed from the surface of the package into the absorbent body, thereby forming a highly compressed portion compressed in the thickness direction and a non-highly compressed portion other than the highly compressed portion which is thicker and has a lower density than the highly compressed portion, The arrangement of the tip surfaces of the protrusions on the anvil roll is developed on a plane, and a virtual lattice is defined in the arrangement region of the tip surfaces, in which first virtual straight lines along a first direction are repeatedly arranged at first intervals in a second direction inclined by 80 to 90 degrees clockwise in a plan view with respect to the first virtual straight lines, and second virtual straight lines along the second direction are repeatedly arranged at second intervals in the first direction; When the smallest imaginary rectangle having vertices at the intersections of the first imaginary line and the second imaginary line is defined, the tip surfaces of the protrusions include a tip surface of a first protrusion arranged at an intersection of the first imaginary line and the second imaginary line, tip surfaces of second protrusions arranged between the tip surfaces of adjacent first protrusions on the first imaginary line and between the tip surfaces of adjacent first protrusions on the second imaginary line, and tip surfaces of third protrusions arranged at intersections of diagonals of the imaginary rectangle, a tip end surface of the first protrusion has a circular shape centered at the intersection of the first virtual line and the second virtual line, a tip surface of the second protrusion has a center of gravity at the midpoint of each side of the imaginary rectangle and is an ellipse or a rounded rectangle having a major axis along each side, a tip surface of the third protrusion has a center of gravity at an intersection of diagonals of the imaginary rectangle and is an ellipse or a rounded rectangle having a long axis along the front-rear direction, or a circle having a center at the intersection of diagonals of the imaginary rectangle, the diameter of the largest inscribed circle inscribed in the outer shape of the tip surface of the protrusion is 2 to 5 mm, and the perimeter of the outer shape of the tip surface of the protrusion is 1 to 2 times the perimeter of the largest inscribed circle inscribed in the outer shape of the tip surface of the protrusion, an area ratio of the tip surfaces of the protrusions in the arrangement region of the tip surfaces is greater than 25.4% and not more than 35%, and a diameter of a maximum inscribed circle inscribed in an outer shape of a portion other than the tip surfaces in the arrangement region of the tip surfaces is 6.5 mm or less, The third step is performed so that the thickness of the highly compressed portion is 30 to 50% of the thickness of the non-highly compressed portion. A method for manufacturing an absorbent element, comprising:

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