Absorbent article

Abstract

To improve both backflow prevention and diffusibility with a simple structure.SOLUTION: An absorbent article includes: an absorber 56 provided within a back and forth direction LD range including a crotch part M; and an absorption element 50 having a packaging sheet 58 wrapping the absorber 56. The absorber 56 is composed by mixing / converging pulp fiber and high absorbent polymer particles. The absorption element 50 is provided with a plurality of high compression parts 51 compressed in a thickness direction TD so that it recesses into the absorber 56 from the surface of the absorption element 50 at intervals, and parts other than the high compression parts 51 in an arrangement area of the plurality of high compression parts 51 are non-compression parts 52 thicker and lower in density than the high compression parts 51. A density of the absorber 56 in the high compression parts 51 is 60,000 to 250,000 g / m3, and an area of each of the high compression parts 51 is 2 to 200 mm2.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to absorbent articles such as disposable diapers, sanitary napkins, incontinence pads, panty liners (disinfectant sheets), and the like. [Background technology]

[0002] The absorbent body (also called absorbent core, etc.) of an absorbent article generally contains pulp fibers and highly absorbent polymer particles. As the pulp fibers, softwood pulp (NBKP) fibers (pulp fibers derived from softwood) have been widely used, but in recent years, the use of hardwood pulp fibers (pulp fibers derived from hardwood) has also been considered because hardwood pulp (LBKP) fibers are relatively cheaper than softwood pulp fibers (see, for example, Patent Documents 1 and 2).

[0003] However, absorbents made by mixing and accumulating pulp fibers containing both hardwood pulp fibers and softwood pulp fibers with superabsorbent polymer particles have the problem that they have lower liquid diffusibility and lower strength (durability) after absorbing liquid compared to absorbents made by mixing and accumulating pulp fibers consisting only of softwood pulp fibers with superabsorbent polymer particles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-014646 A [Patent Document 2] Patent No. 7293479 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, a main object of the present invention is to improve both the strength after absorbing liquid and the liquid diffusibility in an absorbent body containing hardwood pulp fibers. [Means for solving the problem]

[0006] One embodiment of an absorbent article that solves the above problems is described below. <First aspect> It has a crotch area, The absorbent element includes 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 formed by mixing and accumulating pulp fibers including hardwood pulp fibers and highly absorbent polymer particles, The absorbent element has a plurality of highly compressed portions compressed in a thickness direction so as to be recessed from at least one of the front and rear surfaces of the absorbent element into the absorbent body, the highly compressed portions being spaced apart from one another; a portion other than the highly compressed portions in an arrangement region of the plurality of highly compressed portions is a non-highly compressed portion that is thicker and has a lower density than the highly compressed portions, The density of the absorbent body in the highly compressed portion is 60000 to 250000 g / m 3 and The area of ​​each of the highly compressed parts is 2 to 200 mm 2 That is, An absorbent article characterized by:

[0007] (Action and effect) The present inventors have found that the reason for the poor liquid diffusibility and poor strength (durability) after liquid absorption in absorbents containing hardwood pulp fibers is that the fiber length of hardwood pulp fibers is shorter than that of softwood pulp fibers. Therefore, in order to improve the poor liquid diffusibility and strength after liquid absorption, the longer the fiber length of the hardwood pulp fibers, the more preferable it is, but hardwood pulp fibers are naturally derived, and there is a limit to adjusting the characteristics such as fiber length. In addition, reducing the amount of hardwood pulp fibers is not preferable because it reduces the cost advantage. In contrast, when a highly compressed portion having the density and area of ​​this embodiment is provided, the strength and liquid diffusibility after liquid absorption can be improved in an absorbent containing hardwood pulp fibers, as will be clear from the experimental results described later. That is, the highly compressed portion is a high-density portion compressed in the thickness direction by pressing (direct pressure) to have an almost equal thickness, and is the bottom of a depression recessed from at least one of the front and back surfaces of the absorbent element. Such a high-density portion has a property that the intertwining of fibers is difficult to break even if it expands by absorbing liquid. On the other hand, the non-highly compressed portion is a portion that is thicker and has a lower density than the highly compressed portion, but even in the non-highly compressed portion, the absorbent deforms in the vicinity of the highly compressed portion as if pulled by the deformation of the highly compressed portion, and as a result, the density increases as it approaches the highly compressed portion. For this reason, capillary action is strongly expressed in the highly compressed portion, and not only does the liquid retention become higher than the surrounding area, but liquid is also drawn toward the highly compressed portion. Therefore, when each highly compressed portion spaced apart as in the present embodiment has a certain area, the strength of the absorbent body after absorbing liquid is less likely to decrease, and the suction force due to capillary action acts on a larger amount of excreted liquid, causing the excreted liquid absorbed by the absorbent body to spread over a wider area.

[0008] <Second aspect> It has a crotch area, The absorbent element includes 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 formed by mixing and accumulating pulp fibers including hardwood pulp fibers and highly absorbent polymer particles, The absorbent element has a plurality of highly compressed portions compressed in a thickness direction so as to be recessed from at least one of the front and rear surfaces of the absorbent element into the absorbent body, the highly compressed portions being spaced apart from one another; a portion other than the highly compressed portions in an arrangement region of the plurality of highly compressed portions is a non-highly compressed portion that is thicker and has a lower density than the highly compressed portions, Each of the plurality of highly compressed portions has a shortest distance to the nearest other highly compressed portion of 1 to 4 mm. An absorbent article characterized by:

[0009] (Action and effect) In this embodiment, since the highly compressed parts are not excessively sparsely arranged, the strength and liquid diffusibility after liquid absorption can be improved in an absorbent containing hardwood pulp fibers, as will be clear from the experimental results described later. That is, the highly compressed parts are high-density parts compressed in the thickness direction by pressing (direct pressure) to have almost the same thickness, and are the bottom parts of depressions recessed from at least one of the front and back surfaces of the absorbent element. Such high-density parts have the property that the intertwining of fibers is difficult to break even if they expand due to liquid absorption. On the other hand, the non-highly compressed parts are parts that are thicker and have a lower density than the highly compressed parts, but even in the non-highly compressed parts, the absorbent deforms near the periphery of the highly compressed parts as if pulled by the deformation of the highly compressed parts, and as a result, the density increases as it approaches the highly compressed parts. For this reason, capillary action is strongly expressed in the highly compressed parts, and not only does the liquid retention become higher than the surroundings, but liquid is also drawn toward the highly compressed parts. Therefore, when the highly compressed portions are arranged at relatively close intervals as in the present embodiment, the strength of the absorbent body after absorbing liquid is less likely to decrease, and the suction force due to capillary action acts on a larger amount of excreted liquid, causing the excreted liquid absorbed by the absorbent body to spread over a wider area.

[0010] <Third aspect> an area ratio of the highly compressed portions in an arrangement region of the highly compressed portions is 10% to 35%; The diameter of the maximum inscribed circle inscribed in the outer shape of the non-highly compressed portion is 30 mm or less. The absorbent article according to the first or second aspect.

[0011] (Action and effect) When the highly compressed parts are arranged particularly densely as in this embodiment, the liquid diffusibility is further improved. 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, resulting in the advantage that the absorbent body becomes thinner than if there were no highly compressed areas. From these viewpoints, it is particularly preferable that the area ratio of the highly compressed portions is within the above-mentioned range, and that the diameter of the largest inscribed circle inscribed in the outer shape of the non-highly compressed portions is within the above-mentioned range so that the highly compressed portions are not sparsely arranged (so that the non-highly compressed portions are not long and connected in all directions). Conventionally, it has been considered undesirable to arrange highly compressed portions closely together, and therefore, adopting a closely arranged highly compressed portion as in this embodiment does not fall within the scope of optimization that is normally performed.

[0012] <Fourth 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 maximum inscribed circle inscribed in the outer shape of the highly compressed portion is 1 to 10 mm, and the circumferential length of the outer shape of the highly compressed portion is 1 to 15 times the circumferential length of the maximum inscribed circle inscribed in the outer shape of the highly compressed portion. An absorbent article according to a third embodiment.

[0013] (Action and effect) The dimensions and shape of the highly compressed portion can be appropriately determined. However, since 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 shape is excessively complicated, the flexibility of the absorbent body as a whole may be insufficient, or the skin may feel as if a foreign object is mixed in the absorbent body (foreign body sensation). Therefore, it is preferable that the dimensions and shape of the highly compressed portion are within the range of this embodiment.

[0014] <Fifth aspect> In the arrangement region of the plurality of highly compressed portions, first virtual straight lines along a first direction are repeatedly arranged at first intervals in a second direction inclined at 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 a minimum virtual rectangle having vertices at the intersections of the first virtual line and the second virtual line is defined, the highly compressed portion includes a first highly compressed portion disposed at an intersection of the first imaginary straight line and the second imaginary straight line, a second highly compressed portion disposed between adjacent first highly compressed portions on the first imaginary straight line and between adjacent first highly compressed portions on the second imaginary straight line, and a third highly compressed 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 has a center of gravity at the midpoint of each side of the virtual 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 virtual rectangle and is an ellipse or a rounded rectangle having a long axis along the front-rear direction, or a circle centered at the intersection of the diagonals of the virtual rectangle. The absorbent article according to the third or fourth aspect.

[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 with the pattern of this embodiment, the diffusivity in the longitudinal direction (first direction and second direction) of the second highly compressed portion can be improved, and since there are both portions where the non-highly compressed portions are linearly connected in the first direction and portions where the non-highly compressed portions are linearly connected in the second direction, even if the individual highly compressed portions harden, the absorbent body as a whole will be easily deformed to conform to the body surface.

[0016] <Sixth 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 fifth embodiment.

[0017] (Action and effect) When arranging the highly compressed parts along the virtual lattice described above, the dimensions of each highly compressed part can be determined as appropriate, but it is preferable for them to be within the range of this embodiment, as this not only improves liquid diffusion but also improves the ease of deformation of the absorbent body.

[0018] <Seventh aspect> The virtual lattice has an oblique lattice shape in which the first virtual straight line is inclined at 40 to 50 degrees clockwise with respect to the front-rear direction in a plan view, and the second virtual straight line is inclined at 40 to 50 degrees counterclockwise with respect to the front-rear direction in a plan view. The absorbent article according to the fifth or sixth aspect.

[0019] (Action and effect) When arranging the highly compressed parts along a virtual lattice as described above, arranging them in a diagonal lattice pattern as in the present embodiment is preferable because it not only improves the absorbent body's ease of deformation when worn, but also provides excellent liquid diffusion properties.

[0020] <Eighth 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 40:60 to 65:35; The non-highly compressed portion has a thickness of 3 to 13 mm, The thickness of the highly compressed portion is 60 to 90% of the thickness of the non-highly compressed portion. An absorbent article according to any one of the first to seventh aspects.

[0021] (Action and effect) In general, when improving the backflow prevention, the mixing ratio of the highly absorbent polymer particles having high liquid retention is often increased. In addition, in recent years, the mixing ratio of the highly absorbent polymer particles is often increased for the purpose of making the absorbent thinner. However, when the mixing ratio of the highly absorbent polymer particles is increased, not only the shape retention of the highly compressed part is reduced, but also the absorbent body is less likely to deform near the periphery of the highly compressed part in the non-highly compressed part as if pulled by the deformation of the highly compressed part, and the diffusibility may be less improved. In addition, the highly absorbent polymer particles that have absorbed and expanded the excreted liquid are likely to adhere to each other, which inhibits the diffusion of the excreted liquid (gel blocking), and the diffusibility may be less improved. Therefore, it is preferable to set the blending ratio of the pulp fibers and the highly absorbent polymer particles in the absorbent within the range of this embodiment and perform the compression formation of the highly compressed part within the range of this embodiment.

[0022] <Ninth aspect> In the total pulp fibers of the absorbent body, the proportion of pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm is 40% or more by mass, and the proportion of pulp fibers having a fiber width of 10 μm or more and less than 35 μm is 90% or more by mass. The absorbent article according to any one of the first to eighth aspects.

[0023] (Action and effect) By combining hardwood pulp fibers with fibers having a longer average fiber length to achieve the fiber length distribution of the pulp fibers in this embodiment, the absorbent body can have a liquid retention ability due to capillary action while ensuring the absorption capacity and absorption speed, thereby improving the backflow prevention. However, there is still room for improvement in the liquid diffusibility with this alone. Therefore, it is preferable to improve the liquid diffusibility by combining with the highly compressed portion described above.

[0024] <Tenth aspect> The pulp fibers of the absorbent body are made of softwood pulp fibers and hardwood pulp fibers, The mass ratio of the hardwood pulp fibers to the softwood pulp fibers is 25 / 75 or more and 38 / 62 or less. An absorbent article according to a ninth embodiment.

[0025] (Action and effect) As will be seen from the experimental examples described later, it is particularly preferable for the pulp fibers in the absorbent body to have the blend in this embodiment. Effect of the Invention

[0026] The present invention provides advantages such as improved strength and liquid diffusibility after liquid absorption in an absorbent containing hardwood pulp fibers. [Brief description of the drawings]

[0027] [Figure 1] FIG. 2 is a plan view showing the inner surface of the pants-type disposable diaper in an unfolded state. [Diagram 2] FIG. 2 is a plan view showing the outer surface of the pants-type disposable diaper in an unfolded state. [Diagram 3] 2 is a cross-sectional view of FIG. 1 along line 2-2. [Figure 4] 3 is a cross-sectional view of FIG. 1 along line 3-3. [Diagram 5] 1(a) is a cross-sectional view taken along line 4-4 in FIG. 1, and 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 contour 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. [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. 11 is a plan view showing another example of the absorbent body. [Figure 13] FIG. 2 is a cross-sectional view showing the absorbent element in a state before the absorbent body is wrapped in a wrapping sheet. [Figure 14] 4 is a cross-sectional view showing the absorbent element in a state after the absorbent body is wrapped in a wrapping sheet and before the highly compressed portion is formed. FIG. [Figure 15] FIG. 11 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] 5A to 5C are schematic diagrams illustrating a method for manufacturing an absorbent element. [Figure 23] FIG. 13 is an explanatory diagram of a method for measuring the depth of a highly compressed portion. [Figure 24] 1A to 1C are cross-sectional views illustrating various absorbent bodies. [Diagram 25] FIG. 2 is a schematic diagram showing an example of a manufacturing facility for the absorbent element. [Figure 26] FIG. 2 is a schematic diagram showing an example of a manufacturing facility for the absorbent element. [Figure 27] FIG. 2 is a side view showing a schematic diagram of a striking tester. [Figure 28] FIG. 2 is a front view showing a schematic view of a striking tester. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, a pants-type disposable diaper will be described in detail as an example of an absorbent article with reference to the attached drawings. Each component adjacent in the thickness direction is fixed or joined as necessary in the same manner as known diapers, except for the fixed or joined parts described below. The dotted parts in the cross-sectional view indicate an adhesive such as a hot melt adhesive as the fixing or joining means. The hot melt adhesive can be applied by known methods such as slot application, continuous line or dotted line bead application, spiral, Z-shaped, wavy, etc. spray application, or pattern coating (transfer of hot melt adhesive by letterpress printing). Alternatively or in addition to this, at the fixing part of the elastic member, the hot melt adhesive can be applied to the outer circumferential surface of the elastic member to fix the elastic member to the adjacent member. As the hot melt adhesive, for example, EVA-based, adhesive rubber-based (elastomer-based), polyolefin-based, polyester-polyamide-based, and other types are available, but they can be used without any particular limitation. As the fixing or joining means for joining each component, material welding means such as heat sealing and ultrasonic sealing can also be used. In a portion 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 with a hot melt adhesive, intermittent pattern coating in a spiral, Z-shape, wave shape, etc. can be suitably used, and when coating an area greater than the coating width of one nozzle, intermittent pattern coating in a spiral, Z-shape, wave shape, etc. can be performed with or without gaps in the width direction. As a joining means for joining each component, material welding means such as heat sealing and ultrasonic sealing can also be used.

[0029] In addition, as the nonwoven fabric in the following description, known nonwoven fabrics can be appropriately used depending on the part and purpose. The constituent fibers of the nonwoven fabric can be selected without particular limitation from synthetic fibers such as polyolefins such as polyethylene or polypropylene, polyesters, and polyamides (including single-component fibers and composite fibers such as core-sheath fibers), regenerated fibers such as rayon and cupra, and natural fibers such as cotton, and these can also be used in combination. In order to increase the flexibility of the nonwoven fabric, it is preferable to use crimped fibers as the constituent fibers. In addition, the constituent fibers of the nonwoven fabric may be hydrophilic fibers (including fibers that have been made hydrophilic by a hydrophilizing agent), or hydrophobic or water-repellent fibers (including fibers that have been made water-repellent by a water-repellent agent). Furthermore, nonwoven fabrics are generally classified according to the length of the fibers, the sheet formation method, the fiber bonding method, and the laminated structure 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), and the like, and any of these nonwoven fabrics can be used.

[0030] 1 to 6 show an example of a pants-type disposable diaper. The pants-type disposable diaper includes a rectangular front exterior body 12F constituting a front waist area, a rectangular rear exterior body 12B constituting a rear waist area, and an inner body 200 provided inside the exterior bodies 12F and 12B so as to extend from the front exterior body 12F through the crotch area M to the rear exterior body 12B. Both sides of the front exterior body 12F and both sides of the rear exterior body 12B are joined to form side seals 12A, whereby an opening formed by the front and rear ends of the exterior bodies 12F and 12B becomes a waist opening WO through which the wearer's waist passes, and the parts on both sides of the width direction of the inner body 200 that are surrounded by the lower edges of the exterior bodies 12F and 12B and the side edges of the inner body 200 become leg openings LO through which the legs pass. The inner body 200 is a part that absorbs and holds excrement such as urine, and the exterior bodies 12F and 12B are parts that support the inner body 200 against the wearer's body. Furthermore, the symbol Y indicates the overall length of the diaper in its unfolded state (the front-to-back length 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 overall width of the diaper in its unfolded state.

[0031] This pants-type disposable diaper has a waist region T defined as the front-to-rear range having the side seals 12A (the front-to-rear range from the waist opening WO to the upper ends of the leg openings LO), and an intermediate region L defined as the front-to-rear range of the portion forming the leg openings LO (between the front-to-rear region having the side seals 12A of the front body F and the front-to-rear region having the side seals 12A of the rear 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. Usually, when there is a boundary (e.g., the thickness or elongation rate of the elastic member changes) in the front waist portion and the rear waist portion where the stretch stress in the width direction WD changes, the waist portion W is located closer to the waist opening WO than the boundary closest to the waist opening WO, and when there is no such boundary, the waist extension portion 12E extending further toward the waist opening WO than the absorbent body 56 or the inner body 200 is the waist portion W. The length of these in the front-rear direction varies depending on the size of the product and can be appropriately determined, but for example, the waist portion W can be 15 to 40 mm, and the waist lower portion U can be 65 to 120 mm. On the other hand, both side edges of the middle region L are narrowed in a U-shape or curved shape so as to fit around the wearer's legs, and these are the areas where the wearer's legs are inserted. As a result, the pants-type disposable diaper in the opened state has a substantially hourglass shape as a whole.

[0032] (Exterior body) As shown in the figure, the exterior bodies 12F and 12B are made up of a rectangular front exterior body 12F that is a part that constitutes at least the waistline of the front body F, and a rectangular rear exterior body 12B that is a part that constitutes at least the waistline of the back body B. The front exterior body 12F and the rear exterior body 12B may not be continuous on the crotch side and may be separated in the front-to-back direction LD (two-piece exterior type), or may be continuous from the front body to the back body (integrated exterior type) (not shown). The separation distance 12d in the front-to-back direction in the two-piece exterior type can be, for example, about 40 to 60% of the total length Y. In the example shown in the figure, the lower edges of the front exterior body 12F and the rear exterior body 12B are linear along the width direction WD, but at least one of the lower edges of the front exterior body 12F and the rear exterior body 12B may be curved so as to follow the leg circumference.

[0033] In the pants-type disposable diaper with two-part exterior, the interior body 200 is exposed between the front exterior body 12F and the rear exterior body 12B, so that the liquid-impermeable sheet 11 is not exposed on the rear surface of the interior body 200, it is preferable to provide a cover nonwoven fabric 13 on the rear surface of the interior body 200, which extends from between the front exterior body 12F and the interior body 200 to between the rear exterior body 12B and the interior body 200. The inner and outer surfaces of the cover nonwoven fabric 13 can be bonded to the opposing surfaces via a hot melt adhesive. The nonwoven fabric used for the cover nonwoven fabric 13 can be appropriately selected from the same material as the exterior bodies 12F and 12B, for example. Although not shown, the exterior body may be continuous from the front body F to the rear body B through the crotch area. In this case, the exterior body has not only a portion corresponding to the waist area T but also a portion corresponding to the middle area L.

[0034] The front exterior body 12F and the rear exterior body 12B have a front waist portion and a rear waist portion that configure the waist region T. In the example shown in Fig. 1 and Fig. 2, the dimensions of the front exterior body 12F and the rear exterior body 12B in the front-to-rear direction LD are equal, 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 Fig. 7, the front-to-rear dimension of the rear exterior body 12B is longer than that of 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 to the middle region L side. Although not shown, the front exterior body 12F may also be provided with a groin cover portion extending from the waist region T to the middle region L side.

[0035] As shown in Figs. 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 side and the inner side of the elastic members 16-19 described later, respectively, by a joining means 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 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 part and the outer part 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 a part or all of the exterior bodies 12F, 12B. The illustrated example is an example of the former, in which the sheet material 12S forming the outer sheet layer in the waist lower part goes around the waist opening WO side of the sheet material 12H forming the inner sheet layer in the waist lower part and is folded back to the inside thereof, and this folded back part 12r extends so as to cover the end of the inner body 200 on the waist opening WO side. On the other hand, in the waist portion, the folded-back portion 12r forms an inner sheet layer adjacent to the inside of the elastic member.

[0036] The exterior bodies 12F, 12B incorporate elastic members 16-19 to improve the fit around the waist of the wearer, and form an elastic region A2 that elastically stretches in the width direction WD with the elastic members 16-19. In this elastic region A2, the exterior bodies 12F, 12B contract with the contraction of the elastic members when in a natural length state, forming wrinkles or folds, and when stretched in the longitudinal direction of the elastic members, can be stretched to a predetermined stretch rate without wrinkles. As the elastic members 16-19, in addition to elongated elastic members such as rubber threads (illustrated example), known elastic members such as band-shaped, net-shaped, and film-shaped members can be used without any particular limitation. As the elastic members 16-19, synthetic rubber or natural rubber may be used.

[0037] 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-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 waist lower portion U may overlap the inner body 200, or may be provided on both sides in the width direction except for the width direction central portion overlapping with the inner body 200. The waist elastic member 17 has a thickness of 155 to 1880 dtex, particularly about 470 to 1240 dtex (in the case of synthetic rubber; in the case of natural rubber, a cross-sectional area of ​​0.05 to 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 12 mm each, and especially at intervals of 3 to 7 mm, so that the elasticity in the width direction WD of the waist portion W is about 150 to 400%, and especially about 220 to 320%. It is not necessary for the waist portion W to use elastic members of the same thickness or to have the same elasticity in the front-to-rear direction LD, and for example the thickness or elasticity may be different in some parts.

[0038] Additionally, multiple waist-lower elastic members 16, 19 made of elongated elastic members are attached to the waist-lower portion U of the exterior bodies 12F, 12B at intervals in the front-rear direction to form a waist-lower stretchable region (region having waist-lower elastic members 16, 19). The waist-lower elastic members 16, 19 have a thickness of 155 to 1880 dtex, particularly about 470 to 1240 dtex (in the case of synthetic rubber; in the case of natural rubber, a cross-sectional area of ​​0.05 to 1.5 mm 2 , especially 0.1 to 1.0 mm 2 It is preferable to provide about 5 to 30 rubber threads of about 120 mm each at intervals of 1 to 15 mm, especially 3 to 8 mm, so that the elasticity in the width direction WD of the waist lower portion U is about 200 to 350%, especially 240 to 300%. It is not necessary for the waist lower portion U to use elastic members of the same thickness or to have the same elasticity in the front-to-back direction LD, and the thickness or elasticity may be partially different.

[0039] When the elastic members 16, 19 are provided in the front-rear range having the absorbent body 56 as in the lower waist portion U in the illustrated example, in order to prevent the absorbent body 56 from contracting in the width direction WD in part or all of the absorbent body 56, it is preferable that the widthwise middle portion including part or all of the portion overlapping with the absorbent body 56 in the width direction WD is made into a non-elastic region A1, and both sides in the width direction are made into elastic regions A2 (waist lower elastic regions in the illustrated example). The widthwise dimension of the elastic regions A2 provided on both sides of the non-elastic region A1 is almost constant in the front-rear direction LD as in the illustrated example, or can be changed in the front-rear direction LD (not shown). The widthwise dimension of the elastic regions A2 provided on both sides of the width direction WD of the non-elastic region A1 can be almost the same in the front body F and the back body B, or can be different.

[0040] Such stretchable region A2 and non-stretchable region A1 can be constructed by attaching elastic members 16-17, 19 between the inner sheet layer and the outer sheet layer, and then cutting the elastic members 16, 19 into small pieces by applying pressure and heat or cutting at one location in the middle of the width of the region to be the non-stretchable region A1 or over almost the entire region, so that stretchability is retained 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 remain in the non-stretchable region A1.

[0041] The sheet materials 12S, 12H forming the inner sheet layer and the outer sheet layer can be used without any particular limitation, but nonwoven fabric is preferable. When nonwoven fabric is used, the basis weight per sheet is 10 to 30 g / m 2 It is preferable to set the temperature to about 100°C.

[0042] The elastic members 16-19 can be fixed to the exterior bodies 12F, 12B by a known method. The inner sheet layer and the outer sheet layer can also be joined to each other by a known method. For example, in the portion of the exterior bodies 12F, 12B having the elastic members 16-19, a hot melt adhesive HM is applied only to the outer peripheral surfaces of the elastic members 16-19 by an application means such as a comb gun or a surwrap nozzle, and the elastic members 16-19 are sandwiched between the inner sheet layer and the outer sheet layer. This allows the elastic members 16-19 to be fixed to the inner sheet layer and the outer sheet layer, and the inner sheet layer and the outer sheet layer to be fixed, only by the hot melt adhesive HM applied to the outer peripheral surfaces of the elastic members 16-19.

[0043] (Interior body joint) The inner body 200 can be joined to the outer bodies 12F, 12B 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 inner body 200 is fixed to the inner surface 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 root portion 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 in almost the entire overlapping area as shown in FIG. 2, and can also be provided in a portion excluding both ends in the width direction of the inner body 200, for example.

[0044] (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-rear direction LD. As shown in Figs. 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 contact the wearer's legs in order to prevent excrement from leaking out to both sides of the inner body 200.

[0045] (Top sheet) The top sheet 30 is liquid-permeable, and examples of such materials include a perforated or non-perforated nonwoven fabric and a perforated plastic sheet. The top sheet 30 may consist of a single sheet, or may consist of a laminated sheet obtained by bonding two or more sheets together. Similarly, the top sheet 30 may consist of a single sheet, or may consist of two or more sheets in the planar direction.

[0046] Both side portions 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 beyond the side edges of the absorbent element 50.

[0047] The top sheet 30 is desirably fixed to an adjacent member on the back side by a joining means that uses material welding such as heat sealing or ultrasonic sealing, or by a hot melt adhesive, in order to prevent the top sheet 30 from shifting relative to the member on the back side, etc. In the illustrated example, the top sheet 30 is fixed to the front 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 back surface of the top sheet 30.

[0048] (middle seat) In order to allow liquid that has permeated the top sheet 30 to quickly transfer to the absorbent body 56, an intermediate sheet (also called a second sheet) 40, which has a faster liquid permeability rate than the top sheet 30, can be provided. This intermediate sheet 40 is intended to allow liquid to quickly transfer to the absorbent body 56, thereby 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.

[0049] 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, 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 is preferably polyester (PET) with high rigidity. The basis weight is 17 to 80 g / m 2 is preferable, and 25 to 60 g / m 2 The thickness of the raw fiber 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 fiber mixture in order to make the nonwoven fabric bulky.

[0050] 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 region that receives liquid.

[0051] The intermediate sheet 40 is desirably fixed to the adjacent member on the rear side by a joining means such as heat sealing or ultrasonic sealing that uses material welding, or by a hot melt adhesive, in order to prevent the intermediate sheet 40 from being misaligned with respect to the member on the rear side. 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 rear side.

[0052] (Liquid-impermeable sheet) The material of the liquid-impermeable sheet 11 is not particularly limited, but examples thereof include plastic films made of polyolefin resins such as polyethylene and polypropylene, laminated nonwoven fabrics in which a plastic film is provided on the surface of a nonwoven fabric, and laminated sheets in which a nonwoven fabric is laminated and bonded to a plastic film. It is preferable to use a liquid-impermeable and moisture-permeable material that is preferably used from the viewpoint of preventing stuffiness for the liquid-impermeable sheet 11. As a moisture-permeable plastic film, a microporous plastic film obtained by kneading an inorganic filler into a polyolefin resin such as polyethylene or polypropylene, forming a sheet, and then stretching it in a uniaxial or biaxial direction is widely used. 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 methods such as 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 bonded to the cover nonwoven fabric 13 described below via a hot melt adhesive.

[0053] The liquid-impermeable sheet 11 is made to have a width that fits on the back side of 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 side portions 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.

[0054] (Absorption element) The absorbent element 50 has an absorbent body 56 and a wrapping 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 sides of the crotch region M.

[0055] (Absorbent) The absorbent body 56 may extend across both the front and rear sides of the crotch region M so as to include the crotch region M. In the case of a pants-type disposable diaper as in this example, it is preferable that the absorbent body 56 extends to or near the peripheral edge of the inner body 200 in the front-rear direction LD and the width direction WD. The reference symbol 56X indicates the overall width of the absorbent body 56.

[0056] To ensure the amount of absorption in the crotch area M, it is preferable that the absorber 56 has a substantially rectangular shape as in the example shown in Fig. 8. Also, to improve the fit in the crotch area M as in the example shown in Fig. 12(a), it is possible to make the width of the absorber 56 in the crotch area M narrower than both the front and rear sides, giving it a constricted shape. In this case, to ensure the amount of absorption in the crotch area M, it is preferable that the width n1 of the narrowest part of the absorber 56 in the crotch area M is 0.85 times or more the total width 56X of the absorber 56.

[0057] In addition, the crotch region M means the range in the front-rear direction LD having the constricted portion 56n when the absorbent body 56 has the constricted portion 56n described later, and means the range in the front-rear direction LD having the constricted portion of the diaper's outer shape when the absorbent body 56 does not have the constricted portion 56n but has a constricted portion as in the illustrated example, and means the range in the front-rear direction LD having the constricted portion of the diaper's outer shape (between the front exterior body 12F and the rear exterior body 12B in the illustrated example) when the absorbent body 56 has neither constricted portion nor constricted portion, and means the portion located in the center in the front-rear direction LD whose dimension in the front-rear direction LD is 20 to 30% of the total length of the product. The portions extending forward and backward from the crotch region M respectively become the front portion and the rear portion.

[0058] The absorbent body 56 may be a single layer as shown in Figures 3 and 24(a), or may be a multi-layer structure as shown in Figures 24(b) and (c). The layer of the absorbent body 56 is a layer obtained through a fiber stacking process using a predetermined fiber stacking drum and, if necessary, a compression process in the thickness direction. Thus, for example, as shown in Figures 24(b) and (c), the absorbent body 56 may be composed of two layers, an upper layer 56a and a lower layer 56b.

[0059] The sizes of the layers included in the absorbent body 56 may be the same or different. The thicknesses of the layers included in the absorbent body 56 may be the same or different. For example, as shown in FIG. 24(a), the width and thickness of the upper layer 56a and the lower layer 56b included in the absorbent body 56 may be different. In the example shown in FIG. 24(b), the width and thickness of the upper layer 56a are smaller than those of the lower layer 56b. The sizes of the layers included in the absorbent body can be set according to the form and purpose of use of the absorbent article. The number of layers is not limited to two, and may be three or more.

[0060] The thickness of the absorbent body 56 (when the absorbent body is made of multiple layers, the total thickness of the multiple layers) can be 0.5 to 30 mm, preferably 1 to 15 mm. For example, in the case of a disposable diaper, the thickness of the absorbent body 56 can be 1 to 30 mm, preferably 1.5 to 15 mm, more preferably 5 to 13 mm. In the case of a sanitary napkin, the thickness of the absorbent body 56 can be 0.3 to 30 mm, preferably 1.0 to 15 mm. The thickness of the absorbent body 56 may be uniform, or may have regions that are relatively thick or relatively thin.

[0061] The absorbent 56 is a mixture and accumulation of pulp fibers 56f and superabsorbent polymer particles 56p, the pulp fibers 56f and the superabsorbent polymer particles 56p being present almost uniformly throughout the absorbent 56, and the superabsorbent polymer particles 56p being held between the pulp fibers 56f. Such an absorbent 56 can be manufactured using a fiber stacking drum, which will be described later. The absorbent 56 is preferably a mixture and accumulation of only the pulp fibers 56f and the superabsorbent polymer particles 56p, but may contain additives other than the pulp fibers 56f and the superabsorbent polymer particles 56p, such as fillers, pigments, sizing agents, coagulants, oil-resistant agents, aluminum sulfate, retention aids, drainage aids, dry strength agents, wet strength agents, color pigments, water-resistant agents, deodorants, and fragrances, as necessary.

[0062] (Pulp fiber) Pulp is a collection of fibers (pulp fibers) extracted from wood, grass, or other plants by mechanical and / or chemical processing. Pulp can be made from raw materials such as softwood, hardwood, bamboo, rice, kudzu, Japanese silvergrass, hemp, and sugarcane. Pulp made from artificial cellulose such as rayon and acetate can also be used.

[0063] The pulp fibers 56f contained in the absorbent 56 are preferably a mixture of hardwood pulp fibers (pulp fibers derived from hardwood trees) and softwood pulp fibers (pulp fibers derived from softwood trees) having an average fiber length longer than that of hardwood pulp fibers, but may contain only hardwood pulp fibers (100% hardwood pulp fibers). Hereinafter, such an absorbent 56 is also referred to as an absorbent containing hardwood pulp fibers. The hardwood pulp fibers are preferably hardwood bleached kraft pulp (LBKP) produced by the kraft method. The softwood pulp fibers are preferably softwood bleached kraft pulp (NBKP) produced by the kraft method.

[0064] The content of softwood pulp fibers and hardwood pulp fibers in the total pulp fibers 56f is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more. It is also preferable that the total pulp fibers 56f are substantially composed of softwood pulp fibers and hardwood pulp fibers. In this specification, the blending amount of pulp fibers 56f or its material refers to the bone dry internal addition amount, that is, the mass ratio in the bone dry state, unless otherwise specified.

[0065] As shown in Table 1, in the case of the absorbent 56 made of softwood pulp fibers (I), the fiber length and fiber width of the pulp fibers 56f are relatively large, and the variation in fiber length and fiber width is also relatively large, so that the distance between the pulp fibers 56f is generally large, and the obtained absorbent 56 is bulky. Therefore, the absorption capacity (amount of water absorbed) of the pulp fibers 56f is large, and the absorption speed of the absorbent 56 is also relatively fast. However, since the distance between the pulp fibers 56f is large, the liquid retention ability of the fibers due to capillary action is relatively low, and furthermore, the superabsorbent polymer particles (SAP) tend to fall out in the direction of gravity, and the retention of the superabsorbent polymer particles (SAP) between the pulp fibers 56f is somewhat poor. As a result, compared with the absorbents 56 of (II) and (III) below, the liquid retention ability of the absorbent 56 is small, and the effect of suppressing the backflow of liquid is low.

[0066] [Table 1]

[0067] In addition, in the absorbent 56 made of hardwood pulp fibers (II), the fiber length and fiber width of the pulp fibers 56f are relatively small, and the variation in fiber length and fiber width is also relatively small, so the distance between the pulp fibers 56f is small, and the fiber density in the obtained absorbent 56 is also high. Therefore, the absorption capacity (amount of water absorbed) of the pulp fibers 56f is small, and the absorption speed of the absorbent 56 or absorbent article is slow. However, since the distance between the pulp fibers 56f is small, the liquid retention ability of the fibers due to capillary action is high. In addition, the retention of the superabsorbent polymer particles 56p between the pulp fibers 56f is generally good, and the liquid retention ability of the superabsorbent polymer particles 56p is higher than that of the absorbent 56 of (I). As a result, the liquid retention ability of the absorbent 56 is higher than that of the absorbent 56 of (I), and there is also an effect of suppressing the backflow of liquid.

[0068] (III) In the absorbent 56 made of softwood pulp fibers and hardwood pulp fibers, fibers having a relatively long fiber length and a wide fiber width as described above are combined with fibers having a relatively short fiber length and a narrow fiber width, and the fiber density is intermediate between (I) and (II). Therefore, the absorption capacity of the fibers can be secured to a certain extent, the absorption speed of the absorbent 56 can be maintained, and the liquid retention ability of the fibers due to capillary action can be secured. In addition, the high-absorbent polymer particles 56p can be retained between the pulp fibers 56f, and the liquid retention ability of the high-absorbent polymer particles 56p can be further increased compared to (I) and (II). As a result, the absorption capacity and absorption speed of the absorbent 56 can be maintained, and liquid retention ability can also be obtained. In this way, in the form (III), both the absorption capacity and absorption speed and the liquid retention ability can be secured, thereby improving the backflow prevention ability.

[0069] In the above (III), the inclusion of softwood pulp fibers ensures a certain degree of bulkiness in the absorbent body 56, thereby preventing deterioration in the feel of the resulting absorbent article against the skin. The inclusion of softwood pulp fibers also ensures operability when producing fluff pulp from pulp sheets (i.e., the effect of suppressing scattering of powder and suppressing adhesion of fibers to equipment). Good operability contributes to high overall productivity in the manufacture of absorbent articles.

[0070] In one preferred example of the absorbent body 56 containing hardwood pulp fibers, the proportion of pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm is 40% or more by mass, and the proportion of pulp fibers having a fiber width of 10 μm or more and less than 35 μm is 90% or more by mass, in the total pulp fibers of the absorbent body 56. The proportion of pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm can be preferably 42.6% or more, more preferably 43% or more, even more preferably 43.2% or more, 43.7% or more, or 45% or more. The proportion of pulp fibers having a fiber width of 10 μm or more and less than 35 μm can be preferably 90.6% or more, more preferably 91.0% or more, even more preferably 91.2% or more, or 91.4% or more. In this way, the absorbent body 56 contains a specific pulp fiber length and a specific pulp fiber width within each of the specific ranges, and thus the advantage (III) of the absorbent body 56 (particularly the backflow prevention property) can be further improved and made more certain.

[0071] In all pulp fibers 56f of hardwood pulp fiber-containing absorbent 56, the upper limit of the proportion of pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm is not particularly limited, but due to the variation in fiber length caused by pulp being a natural material, it can be 80 mass % or less, 60 mass % or less, or 55 mass % or less. Similarly, the upper limit of the proportion of pulp fibers having a fiber width of 10 μm or more and less than 35 μm is not particularly limited, but can be 98 mass % or less, 95 mass % or less, or 94 mass % or less.

[0072] The fiber length and fiber width of pulp fibers can be measured using the measuring instrument "VALMET FS5" in accordance with JIS-P8226:2011 (ISO16065-2:2007) "Pulp - Fiber length measurement method by optical automatic analysis method."

[0073] Furthermore, in absorbent body 56 containing hardwood pulp fibers, the average fiber length when pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm are measured at 0.02 mm intervals (classification width of 0.02 mm) can be 0.5 to 0.8 mm, preferably 0.6 to 0.7 mm. This makes it possible to suppress the variation in the distribution of voids in absorbent body 56 that may occur depending on the orientation direction of the pulp fibers, and ensure the absorption rate.

[0074] Furthermore, in the hardwood pulp fiber-containing absorbent 56, the standard deviation σ when pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm are measured at 0.02 mm intervals (classification width of 0.02 mm) can be 0.58 mm or less, preferably 0.56 mm or less, more preferably 0.54 mm or less, and even more preferably 0.50 mm or less. By having the standard deviation in the above range, it is possible to improve the absorption capacity and absorption speed of the absorbent 56, and to improve the backflow prevention properties.

[0075] Furthermore, the average fiber width when pulp fibers having a fiber width of 10 μm or more and less than 35 μm are measured at 1 μm intervals (classification width of 1 μm) can be 15 μm or more and 30 μm or less, preferably 18 μm or more and 27 μm or less. By setting the average fiber width within the above range, it is possible to maintain the gap between the fibers appropriately and prevent a decrease in the absorption rate, and to avoid the contact area between the pulp fibers from becoming too large, thereby preventing an excessive increase in the bonding strength between the fibers. This allows the defibration property during production to be appropriate. Note that if the defibration property of the pulp sheet is excessively low, over-defibration will occur during the production of the fluff pulp (excessive defibration work will be performed), and there is a risk that the absorption rate of the resulting absorbent will decrease due to the generation of fine fibers.

[0076] The standard deviation σ when pulp fibers having a fiber width of 10 μm or more and less than 35 μm are measured at 1 μm intervals (classification width of 1 μm) can be 2.9 μm or less, preferably 2.8 μm or less, more preferably 2.75 μm or less, and even more preferably 2.6 μm or less, 2.59 μm or less. By keeping the standard deviation within the above range, it is possible to improve the absorption speed and the backflow prevention effect.

[0077] As described above, the hardwood pulp fiber-containing absorbent 56, which has reduced variation in the distribution of fiber lengths within a specific range and the distribution of fiber widths within a specific range, has good backflow prevention effects while maintaining absorption capacity and absorption speed, despite the incorporation of hardwood pulp fibers.

[0078] The raw material wood for the coniferous pulp fibers contained in the pulp fibers is not particularly limited, but pines such as radiata pine and various cedars are preferably used.

[0079] In addition, the raw wood of the hardwood pulp fiber is not particularly limited, but acacia wood, eucalyptus wood, etc. are preferably used. Acacia wood is a material that has the characteristics of being less shrinkage due to drying, resistant to impact, strong and hard, and the pulp obtained from acacia wood also inherits the original properties and is a useful raw material pulp with high moisture absorption and drying properties. Eucalyptus wood belongs to the genus Eucalyptus, and in particular Eucalyptus globulus, Eucalyptus grandis, Eucalyptus europhylla, Eucalyptus nitens, Eucalyptus regnans, etc. have been widely used as raw pulp materials for paper manufacturing since ancient times, and the obtained pulp fibers have a fiber lumen that is difficult to crush and is rigid, and by blending this pulp fiber, the absorbent can be made bulky and low-density. As hardwood pulp fiber, acacia wood is preferable because it has a bulky fiber width larger than eucalyptus wood, and there is little decrease in the absorption amount and absorption speed even when combined with softwood pulp fiber.

[0080] In the hardwood pulp fiber-containing absorbent 56, the mass ratio of hardwood pulp fibers to other pulp fibers such as softwood pulp fibers is not limited and can be, for example, 10 / 90 to 90 / 10. From the standpoint of operability, however, it is preferably 20 / 80 to 50 / 50, more preferably 25 / 75 to 38 / 62, even more preferably 25 / 75 or more and less than 38 / 62, even more preferably 26 / 74 to 36 / 64, and particularly preferably 28 / 72 to 35 / 65.

[0081] The content of acacia wood in the raw wood material of hardwood pulp fibers, i.e., the content of pulp fibers derived from acacia wood in hardwood pulp fibers in hardwood pulp fiber-containing absorbent 56, can be preferably 5 to 95% by mass, more preferably 5% by mass or more and less than 95% by mass, and even more preferably 20 to 93% by mass, 20 to 90% by mass, 25 to 85% by mass, or 50 to 80% by mass. Even if hardwood pulp fibers have a shorter fiber length than softwood pulp fibers and tend to be densely packed together, and even if the fibers are oriented in any direction (for example, in any direction of the length, width, and / or thickness of the obtained absorbent article), the voids between the fibers can be more uniformly secured.

[0082] As the pulp fibers constituting the absorbent 56, in addition to the above-mentioned softwood bleached kraft pulp and hardwood bleached kraft pulp, for example, soda pulp, sulfite pulp, chemi-thermomechanical pulp, chemi-finer mechanical pulp, thermo-chemi-mechanical pulp, etc. may be used. However, if the lignin in the fibers is not sufficiently removed, the absorption amount and absorption rate of the pulp fibers are likely to decrease, so bleached pulp from which lignin has been sufficiently removed is preferred. When the other pulps are contained, the content of the other pulps is preferably 10% by mass or less based on the total pulp raw material.

[0083] Furthermore, the pulp fibers 56f contained in the absorbent 56 may contain recycled pulp fibers (recycled pulp fibers) regardless of the type. For example, the pulp fibers 56f may contain recycled softwood pulp fibers and recycled hardwood pulp fibers. When recycled pulp fibers are used, the amount of ash in the pulp fibers used in the absorbent, for example, the amount of ash in fluff pulp, is preferably as small as possible. When recycled pulp fibers are used, when comparing pulps derived from the same raw material before and after recycling, the whiteness of the recycled pulp may be lower than or equal to the whiteness of virgin pulp (unregenerated pulp or unregenerated pulp), but it is preferable that they are equal.

[0084] When the absorbent body 56 has multiple layers, only some of the layers may contain hardwood pulp fibers, or all of the layers may contain hardwood pulp fibers. For example, when the absorbent body 56 is composed of two layers, an upper layer 56a and a lower layer 56b, only the lower layer 56b may contain hardwood pulp fibers, or only the upper layer 56a, which may directly contact the skin, may contain hardwood pulp fibers.

[0085] The basis weight of the pulp fibers 56f in the absorbent body 56 (the basis weight of the entire layers when the absorbent body is made of multiple layers) is 100 to 500 g / m 2 , preferably 100 to 300 g / m 2 , particularly preferably 120 to 250 g / m 2 For example, in the case of a disposable diaper, the weight of the pulp fiber can be 100 to 300 g / m 2 , preferably 120 to 200 g / m 2 In the case of a sanitary napkin, for example, the basis weight of the pulp fibers in the absorbent body 56 (the basis weight of the entire absorbent body in the case of a multi-layer absorbent body) can be 150 to 500 g / m 2 , preferably 250 to 400 g / m 2 The basis weight of the pulp fibers may be uniform overall, or there may be regions with relatively high or relatively low basis weight.

[0086] (Superabsorbent polymer particles) The superabsorbent polymer particles 56p include not only "particles" but also "powder". The superabsorbent polymer particles 56p may be those used in this type of disposable diaper. The pre-swelling particle size (particle size before absorbing liquid) of the superabsorbent polymer particles 56p is not particularly limited, but the superabsorbent polymer particles 56p having a pre-swelling particle size of more than 150 μm and not more than 850 μm are preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more of the total amount. In addition, the superabsorbent polymer particles 56p having a pre-swelling particle size (for example, not more than 600 μm, more preferably not more than 500 μm) shorter than the average fiber length of hardwood pulp fibers are preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more of the total amount.

[0087] The particle size distribution of the superabsorbent polymer particles 56p can be obtained by setting standard sieves (e.g., standard sieves manufactured by Tokyo Screen Co., Ltd.) with openings of 850 μm, 600 μm, 500 μm, 355 μm, 300 μm, 250 μm, and 150 μm as specified in JIS Z 8801 and a tray in this order from top to bottom in a shaker (e.g., AS200 type manufactured by Recce Co., Ltd.), and putting the entire amount of superabsorbent polymer particles into the topmost sieve and sieving it. The shaking conditions are 50 Hz, amplitude 0.5 mm, and shaking time 10 minutes. In addition, the sieving is performed in an environment with a temperature of 23 ± 2 ° C and a humidity of 50 ± 5%, and the sample is stored in the same environment for 24 hours or more before sieving and then measured. Sieving is performed three times, and the average of the three times is taken as the sieved mass of each sieve. From the mass of the superabsorbent polymer particles on each sieve and the total mass (mass of all superabsorbent polymer particles), the content ratio (mass percentage) of the particle size range corresponding to each sieve (i.e., more than 850 μm, more than 600 μm and less than 850 μm, more than 500 μm and less than 600 μm, more than 355 μm and less than 500 μm, more than 300 μm and less than 355 μm, more than 250 μm and less than 300 μm, more than 150 μm and less than 250 μm, and less than 150 μm) can be obtained. In addition, a particle size cumulative curve is obtained based on this particle size distribution, and the particle size corresponding to the median cumulative value (50%) of the cumulative curve is taken as the average particle size. The average particle size of the superabsorbent polymer particles is preferably in the range of 355 to 500 μm, and more preferably in the range of 370 to 470 μm.

[0088] The material of the superabsorbent polymer particles 56p is not particularly limited, but preferably has a water absorption of 40 g / g or more. The superabsorbent polymer particles 56p may be starch-based, cellulose-based, or synthetic polymer-based (polyacrylate-based, polysulfonate-based, maleic anhydride-based), and may be starch-acrylic acid (salt) graft copolymer, saponified starch-acrylonitrile copolymer, crosslinked product of sodium carboxymethylcellulose, or acrylic acid (salt) polymer. The shape of the superabsorbent polymer particles 56p is preferably a powder-like shape that is usually used, but other shapes may also be used.

[0089] The highly absorbent polymer particles 56p preferably have a water absorption speed of 70 seconds or less, particularly 40 seconds or less. If the water absorption speed is too slow, backflow (liquid supplied into the absorbent body 56 flows back out of the absorbent body 56) is likely to occur.

[0090] The highly absorbent polymer particles 56p preferably have a gel strength of at least 1000 Pa. This makes it possible to effectively prevent the absorbent body 56 from feeling sticky after absorbing liquid, even if the absorbent body 56 is bulky.

[0091] The basis weight of the highly absorbent polymer particles 56p can be appropriately determined depending on the absorption amount required for the application of the absorbent body 56. Therefore, although it cannot be generally stated, the basis weight of the highly absorbent polymer particles 56p in the absorbent body 56 (the basis weight of the entire layer when the absorbent body 56 is composed of multiple layers) is 50 to 350 g / m 2 , preferably 100 to 300 g / m 2 For example, in the case of a disposable diaper, the basis weight of the highly absorbent polymer particles 56p can be set to 50 to 300 g / m 2 , preferably 100 to 250 g / m 2 In the case of a sanitary napkin, for example, the basis weight of the highly absorbent polymer particles 56p in the absorbent body 56 (the basis weight of the entire layer when the absorbent body 56 is made of multiple layers) can be 70 to 470 g / m 2 , and preferably 140 to 240. When the absorbent body 56 has two layers, the basis weight of the superabsorbent polymer particles 56p in the lower layer 56b may be different from the basis weight of the superabsorbent polymer particles 56p in the upper layer 56a. That is, the basis weight of the superabsorbent polymer particles 56p in the lower layer 56b may be greater than the basis weight of the superabsorbent polymer particles 56p in the upper layer 56a, or conversely, the basis weight of the superabsorbent polymer particles 56p in the lower layer 56b may be less than the basis weight of the superabsorbent polymer particles in the upper layer 56a.

[0092] The ratio of the pulp fibers 56f and the highly absorbent polymer particles 56p in the absorbent body 56 is not particularly limited, and can be, for example, a weight ratio of the pulp fibers 56f:high absorbent polymer particles 56p of 40:60 to 65:35.

[0093] The average particle diameter of the superabsorbent polymer particles 56p after swelling is preferably 2,000 to 3,000 μm, and more preferably 2,200 to 2,800 μm. The average particle diameter of the superabsorbent polymer particles 56p after swelling means the average diameter of the superabsorbent polymer particles 56p in a swollen state after immersing them in physiological saline for 60 minutes and then draining them for 15 minutes. This average diameter is obtained by observing the group of superabsorbent polymer particles 56p in a swollen state from one direction with a microscope at a magnification of 50 times, measuring the maximum diameter of any 20 particles that are entirely visible on the surface of the group of superabsorbent polymer particles 56p, and taking the arithmetic average. In particular, if the average particle diameter of the superabsorbent polymer particles 56p after swelling is larger than the average fiber length of the hardwood pulp fibers, the entanglement between the pulp fibers 56f is easily broken by the expansion of the superabsorbent polymer particles 56p, and the expansion of the superabsorbent polymer particles 56p is less likely to be inhibited (so-called gel blocking is less likely to occur), which is preferable.

[0094] (Low weight area) The absorbent 56 may have elongated low basis weight parts 56L extending in the front-rear direction LD on both sides of the width direction WD in the crotch area M as in the example shown in Figs. 1 to 4, or may not have low basis weight parts 56L (not shown). The low basis weight parts 56L refer to parts with a low basis weight, and do not include parts that are compressed in the thickness direction TD but do not change the basis weight, such as the highly compressed parts 51 described later. The low basis weight parts 56L may be slits that penetrate in the thickness direction TD, but are preferably recesses with a low accumulation of pulp fibers and highly absorbent polymer particles as in the example shown, because this makes it easier to ensure the amount of absorption. The recesses may be formed on the front or back surface of the absorbent 56. By providing the absorbent 56 with such low basis weight parts 56L, the absorbent 56 is encouraged to bend along the low basis weight parts 56L, improving the fit of the absorbent element 50 in the crotch area 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.

[0095] The low basis weight portion 56L may extend linearly along the front-rear direction LD as long as it is elongated in the front-rear direction LD, or may be curved so as to be positioned laterally as it approaches both sides in the front-rear direction LD as in the illustrated example. The front and rear ends of the low basis weight portion 56L may be appropriately shaped, for example, as shown in FIG. 12(a) as a straight line, as shown in FIG. 8 as a curved bulge (semicircular arc, etc.), or, although not shown, may have rounded corners at both ends and a straight line in the middle. The width m1 of the low basis weight portion 56L may be appropriately determined, and may be, for example, 0.04 to 0.1 times the width n1 (meaning the overall width 56X in the case of a rectangle) of the narrowest portion in the crotch portion M of the absorbent body 56. The width m1 of the low basis weight portion 56L may be constant in its length direction or may vary. The dimensions and arrangement of the low basis weight portion 56L in the front-rear direction LD may be appropriately determined. For example, the dimension m2 of the low weight portion 56L in the front-to-back direction LD can be 50 to 120%, and more preferably 50 to 80%, of the dimension in the front-to-back direction LD of the crotch portion M. In addition, the low weight portion 56L may be contained within the crotch portion M, or may protrude to the front, rear, or both the front and rear sides of the crotch portion M.

[0096] As shown in FIG. 8, the low weight portion 56L may be provided on both sides of the crotch portion 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 portion M in the width direction WD.

[0097] (High compression section) In the absorbent element 50, as shown in Figs. 3, 4, 9 to 11, a plurality of highly compressed parts 51 compressed in the thickness direction TD from the surface of the absorbent element 50 to the inside of the absorbent body 56 are provided at intervals. In addition, in the arrangement region of the plurality of highly compressed parts 51 (a rectangular region having sides along the front-rear direction LD and the width direction WD, respectively, and circumscribing all of the highly compressed parts 51), the portion other than the highly compressed parts 51 is a non-highly compressed part 52 that is thicker and has a lower density than the highly compressed parts 51. The highly compressed parts 51 are high-density parts compressed by pressing (direct pressure) to have almost the same thickness, and are the bottom of the depression. On the other hand, the non-highly compressed parts 52 are thicker and have a lower density than the highly compressed parts 51, but even in the non-highly compressed parts 52, the absorbent body 56 deforms in such a way that it is pulled by the deformation of the highly compressed parts 51 near the periphery of the highly compressed parts 51, and as a result, the density increases as it approaches the highly compressed parts 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 any depressions on either or both of the front and back surfaces of the absorbent element 50.

[0098] The highly compressed portion 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 portion 51), or may be provided only in a part of the front-rear direction or a part of the width direction of the absorbent element 50. For example, although not shown, the highly compressed portion 51 may be provided only in a middle region in the front-rear direction LD including the crotch region M, or conversely, the highly compressed portion 51 may not be provided in the middle region in the front-rear direction LD including the crotch region M, but may be provided only in the regions on both the front and rear sides of the middle region. In addition, the highly compressed portion 51 in the illustrated example is not recessed from the surface of the sheet (top sheet 30 and intermediate sheet 40 in the illustrated example) located on the front side of the absorbent element into the absorbent body 56, but 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 50 into the absorbent body 56.

[0099] The density of the absorbent body 56 in the highly compressed portion 51 is not particularly limited, but is preferably 60,000 to 250,000 g / m3 It is preferable that the thickness is 65,000 to 200,000 g / m 3 On the other hand, the density of the absorbent body 56 in the non-highly compressed portion 52 is not particularly limited, but is preferably 50,000 to 200,000 g / m 3 It is preferable that the thickness is 55,000 to 150,000 g / m 3 The density of the absorbent body 56 in the highly compressed portion 51 and the non-highly compressed portion 52 is measured by the following method.

[0100] (Method of measuring density of absorbent body 56 in highly compressed portion 51) (1) At least one of the front and back sheets of the absorbent element 50 is peeled off so that the surface having the highly compressed portions 51 of the absorbent element 50 is exposed, and the area of ​​the highly compressed portions 51 is measured by the method described below. (2) The basis weight of the absorbent element 50 is measured. (3) A portion of the packaging sheet 58 is cut away from the absorbent element 50, and the basis weight of the packaging sheet 58 is measured. (4) From the measurement results of (1) and (2) above, the mass of the absorbent element 50 in the highly compressed portion 51 is determined, and from the measurement results of (1) and (3) above, the mass of the packaging sheet 58 in the highly compressed portion 51 is determined, and the latter is subtracted from the former to determine the mass of the absorbent body 56 in the highly compressed portion 51. (5) After the absorbent element 50 is frozen with liquid nitrogen, it is cut in the thickness direction TD so as to cross approximately the center of the highly compressed portion 51, and the cut surface is observed under a microscope to measure the thickness of the absorbent body 56. (6) Assuming that the thickness of the absorbent 56 in the highly compressed portion 51 is constant, the volume of the absorbent 56 in the highly compressed portion 51 is calculated by multiplying the area of ​​the highly compressed portion 51 in (1) above by the thickness of the absorbent 56 in (5) above. (7) The density of the absorbent body 56 in the highly compressed portion 51 is calculated by dividing the above (4) by the above (6).

[0101] (Method for measuring absorbent density in non-highly compressed parts) (1) At least one of the sheets on the front and back sides of the absorbent element 50 is peeled off so as to expose the surface having the non-highly compressed portions 52 of the absorbent element 50, and five rectangular measurement target areas of predetermined dimensions are marked using a pen on the non-highly compressed portions 52. The dimensions of the measurement target areas are measured to find their area. (2) The basis weight of the absorbent element 50 is measured. (3) A portion of the packaging sheet 58 is cut away from the absorbent element 50, and the basis weight of the packaging sheet 58 is measured. (4) From the measurement results of (1) and (2) above, the mass of the absorbent element 50 in the area to be measured is determined, and from the measurement results of (1) and (3) above, the mass of the packaging sheet 58 in the area to be measured is determined, and the mass of the absorbent body 56 in the area to be measured is determined by subtracting the latter from the former. (5) After the absorbent element 50 is frozen with liquid nitrogen, it is cut in the thickness direction TD so as to cross approximately the center of the measurement target area, and the thickness of the absorbent body 56 is measured by observing the cut surface under a microscope. (6) Assuming that the thickness of the absorbent body 56 in the measurement area is constant, the volume of the absorbent body 56 in the measurement area is calculated by multiplying the area of ​​the measurement area in (1) above by the thickness of the absorbent body 56 in (5) above. (7) The density of the absorbent body 56 in the non-highly compressed portion 52 is calculated by dividing the above (4) by the above (6).

[0102] The area of ​​each highly compressed portion 51 is not particularly limited, but is preferably 2 to 25 mm 2 It is preferable that the thickness is about 3 to 15 mm. 2 It is particularly preferred that:

[0103] The highly compressed portions 51 are high-density portions compressed in the thickness direction TD by pressing (direct pressure) to have a substantially uniform thickness, and are the bottoms of depressions recessed from at least one of the front and back surfaces of the absorbent element 50. Such high-density portions have the property that the intertwining of fibers is unlikely to be broken even if they expand due to liquid absorption. On the other hand, the non-highly compressed portions 52 are thicker and have a lower density than the highly compressed portions 51, but 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 become higher than the surroundings, but liquid is also drawn toward the highly compressed portions 51. Therefore, when each of the highly compressed portions 51 spaced apart from one another has a certain degree of density and area, in an absorbent 56 containing hardwood pulp fibers, the strength of the absorbent 56 after absorbing liquid is less likely to decrease, and the suction force due to capillary action acts on a larger amount of excrement, causing the excrement absorbed by the absorbent 56 to spread over a wider area.

[0104] Although not shown, the absorbent element 50 may be compressed in the thickness direction TD so as to be recessed from both the front and back sides into the absorbent body 56, or the highly compressed portion 51 may be compressed in the thickness direction TD so as to be recessed only from the back side of the absorbent element 50 into the absorbent body 56, in which case a recess is formed on the back side of the absorbent element 50. However, as in the illustrated example, when the highly compressed portion 51 is compressed in the thickness direction TD so as to be recessed from at least the front side of the absorbent element 50 into the absorbent body 56, both the backflow prevention property and the diffusibility are improved. That is, as described above, the capillary phenomenon is strongly expressed in the highly compressed portion 51, and not only does the liquid retention property become higher than the surrounding area, and not only does the liquid get drawn toward the highly compressed portion 51, but the excreted liquid collected by the highly compressed portion 51 can be strongly held in a portion far from the skin. As a result, backflow is less likely to occur.

[0105] Also, the shortest distance d4 between the nearest other highly compressed parts 51 can be about 1 to 4 mm, and is preferably about 1.5 to 3.5 mm. When the highly compressed parts 51 are arranged at fairly close intervals in this manner, the strength of the absorbent body 56 after absorbing liquid is less likely to decrease, and the suction force due to capillary action acts on a larger amount of excreted liquid, so that the excreted liquid absorbed by the absorbent body 56 is diffused over a wider range. When the highly compressed parts 51 are arranged at such intervals and have a certain area, the distance between the pulp fibers 56f in the highly compressed parts 51 is shortened, which leads to strengthening of the entanglement of the pulp fibers 56f, reduction of the gaps between the pulp fibers 56f that serve as the movement path of the superabsorbent polymer particles 56p, and an increase in the contact area of ​​the pulp fibers 56f with the superabsorbent polymer particles 56p, and thus the movement of the superabsorbent polymer particles 56p within the absorbent body 56 and the movement of the superabsorbent polymer particles 56p outside the absorbent body 56 are suppressed. In other words, the retention of the highly absorbent polymer particles 56p in the absorbent body 56 containing hardwood pulp fibers is improved.

[0106] 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 maximum inscribed circle 54 inscribed in the outer shape of the non-highly compressed portions 52 is preferably 30 mm or less, more preferably 10 mm or less, even more preferably 6.5 mm or less, even more preferably 6 mm or less, and particularly preferably 5 mm or less. The lower limit of the diameter of the maximum inscribed circle 54 inscribed in the outer shape of the non-highly compressed portions 52 is preferably 2 mm, more preferably 3 mm, and particularly preferably 4 mm.

[0107] In this way, when the highly compressed parts 51 are arranged particularly densely, the liquid diffusibility described above is further improved. In addition, the retention of the highly absorbent polymer particles 56p is further improved. Furthermore, even in the case of non-highly compressed parts 52, the absorbent body 56 is deformed in the vicinity of the highly compressed parts 51 as if pulled by the deformation of the highly compressed parts 51, which results in an advantage that the absorbent body 56 becomes thinner than when there are no highly compressed parts 51. From these points of view, it is particularly preferable that the area ratio of the highly compressed parts 51 is within the above-mentioned range. In addition, it is particularly preferable that the diameter of the maximum inscribed circle 54 inscribed in the outer shape of the non-highly compressed parts 52 is small so that the highly compressed parts 51 are not arranged sparsely (so that the non-highly compressed parts 52 are not long and connected in all directions).

[0108] The dimensions and shape of the highly compressed portion 51 can be appropriately determined. However, since the highly compressed portion 51 is a hard portion, if the dimensions of the highly compressed portion 51 are excessively large, if the shape of the highly compressed portion 51 is excessively long in one direction, or if the highly compressed portion 51 has an excessively complicated outer shape, 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). In addition, if the dimensions of the highly compressed portion 51 are excessively small, if the shape of the highly compressed portion 51 is excessively long in one direction, or if the highly compressed portion 51 has an excessively complicated outer shape, there is also a problem that the packaging sheet 58 is easily torn when the packaging sheet 58 is made of crepe paper. Therefore, the diameter of the maximum inscribed circle 53 inscribed in the outer shape of the highly compressed portion 51 is preferably 1 to 10 mm, more preferably 1 to 6 mm, even more preferably 2 to 5 mm, and particularly preferably 2.5 to 3.5 mm. Furthermore, the circumferential length of the outer shape of the highly compressed portion 51 is preferably 1 to 15 times the circumferential length of the maximum inscribed circle 53 inscribed in the outer shape of the highly compressed portion 51, more preferably 1 to 5 times, even more preferably 1.0 to 2.5 times, even more preferably 1.0 to 2.0 times, and particularly preferably 1.0 to 1.6 times.

[0109] As an example, 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.

[0110] The shortest dimension of each highly compressed portion 51 is not particularly limited, but is preferably longer than the average fiber length of hardwood pulp fibers, more preferably 4 times or more, even more preferably 4 to 10 times, and particularly preferably 4 to 12 times. When the shortest dimension of each highly compressed portion 51 is longer than the average fiber length of hardwood pulp fibers, there is an advantage that the pulp is less biased and the shape retention of the absorbent can be improved. In addition, the shortest dimension of each highly compressed portion 51 is preferably longer than the average particle size of the superabsorbent polymer particles 56p after swelling, more preferably 1.5 times or more, even more preferably 1.5 to 6 times, and particularly preferably 1.5 to 5 times. When the shortest dimension of each highly compressed portion 51 is longer than the average particle size of the superabsorbent polymer particles 56p after swelling, there is an advantage that the retention of the superabsorbent polymer particles is improved and the bias of the absorption performance can be reduced.

[0111] The external shape of the highly compressed portion 51 is not particularly limited, and a shape that does not have an inflection point or 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), is preferable, but it may also be a triangle, a rectangle, a cloud, an X-shape, a V-shape, a U-shape, etc.

[0112] In general, when improving the backflow prevention property, the mixing ratio of the highly absorbent polymer particles having high liquid retention is often increased. In addition, in recent years, the mixing ratio of the highly absorbent polymer particles is often increased for the purpose of making the absorbent 56 thinner. However, when the mixing ratio of the highly absorbent polymer particles is increased, not only does the shape retention of the highly compressed portion 51 decrease, but the absorbent 56 becomes difficult to deform in the vicinity of the highly compressed portion 51 in the non-highly compressed portion 52 as if pulled by the deformation of the highly compressed portion 51, and there is a concern that the low backflow property and the diffusibility are difficult to improve. In addition, the highly absorbent polymer particles that have absorbed and expanded the excreted liquid are likely to adhere to each other, which inhibits the diffusion of the excreted liquid (gel blocking), and therefore the diffusibility is likely to be difficult to improve. Therefore, the basis weight of the pulp fiber in the absorbent 56 is set to 100 to 500 g / m 2 In this case, the weight ratio of pulp fibers:superabsorbent polymer particles in the absorbent body 56 is preferably 45:55 to 65:35.

[0113] 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 and diffusion. Therefore, when the above-mentioned range of basis weight of pulp fiber and the range of ratio of pulp fiber and highly absorbent polymer particles are adopted, the thickness 50t of the absorbent element 50 (thickness of non-highly compressed portion 52) is preferably 3 to 13 mm. In this case, the thickness 51t of the highly compressed portion 51 (minimum value when the thickness varies) can be determined as appropriate, but in general, it is preferably 60 to 90% of the thickness 50t of the absorbent element 50.

[0114] The highly compressed parts 51 can be arranged in a regular or irregular pattern as appropriate. For example, the highly compressed parts 51 can be arranged in a grid pattern in which the highly compressed parts 51 arranged in a dotted line shape as shown in FIG. 17, in a pattern in which the dotted highly compressed parts 51 are arranged in a staggered or matrix shape as shown in FIG. 18 and FIG. 19, or in a pattern in which the X-shaped highly compressed parts 51 are arranged in a matrix shape as shown in FIG. 20. Although not shown, the highly compressed parts may be arranged in a grid pattern in which linearly continuous highly compressed parts are arranged, or in a pattern in which highly compressed parts of different sizes and shapes are arranged at intervals to form a predetermined pattern. In particular, when the highly compressed parts 51 arranged in a dotted line shape or the highly compressed parts 51 arranged in a grid pattern in which the movement of the highly absorbent polymer particles 56p of the non-highly compressed parts 52 is restricted to within the area surrounded by the highly compressed parts 51, the uneven distribution of the highly absorbent polymer particles 56p can be suppressed with fewer highly compressed parts 51. For example, as shown in FIG. 21, a pattern may be used in which a plurality of highly compressed portions 51 with different areas are arranged, and the area of ​​the largest highly compressed portion 51 is three times or more than the area of ​​the smallest highly compressed portion 51. The pattern shown in FIG. 21 includes a plurality of linear highly compressed portions 51 with the same width and different lengths, and the length of the longest highly compressed portion 51 is three times or more than the length of the shortest highly compressed portion 51. In addition, in the pattern shown in FIG. 21, a highly compressed portion 51 extending in the front-rear direction LD, a highly compressed portion 51 extending in a diagonal direction, and a highly compressed portion 51 having a portion extending in the front-rear direction LD and portions extending in a diagonal direction from both front and rear ends of the highly compressed portion 51 are arranged in combination. Note that, although the dimensions of each portion are shown in FIG. 17 to FIG. 21, these dimensions are merely examples, and it goes without saying that they can be individually changed as appropriate.

[0115] A preferred pattern of the highly compressed portion 51 is an example shown in FIG. 11 and FIG. In this example, in the arrangement area of ​​the high compression portion 51, first virtual straight lines 81 along a first direction are repeatedly arranged at first intervals 81d in a second direction inclined by 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 minimum virtual rectangle 83 having an apex at the intersection of the first virtual straight line 81 and the second virtual straight line 82 is defined, the high compression portion 51 is composed of a first high compression portion 51a arranged at the intersection of the first virtual straight line 81 and the second virtual straight line 82, second high compression portions 51b arranged between adjacent first high compression portions 51a on the first virtual straight line 81 and between adjacent first high compression portions 51a on the second virtual straight line 82, and a third high compression portion 51c arranged at the intersection of the diagonals of the virtual rectangle. The first highly compressed portion 51a is a circle centered on the intersection of the first virtual line 81 and the second virtual line 82, the second highly compressed portion 51b is a rounded rectangle (or may be an ellipse) having a center of gravity at the midpoint of each side of the virtual rectangle and a long axis along each side, and the third highly compressed portion 51c is a rounded rectangle (or may be an ellipse or a circle centered on the intersection of the diagonals of the virtual rectangle) having a center of gravity at the intersection of the diagonals of the virtual rectangle and a long axis along the front-rear direction LD. In this pattern, the diffusibility in the long axis direction (first direction and second direction) of the second highly compressed portion 51b can be improved, and since the non-highly compressed portions 52 have both a portion where they are linearly continuous in the first direction and a portion where they are linearly continuous in the second direction, even if each highly compressed portion 51 hardens, the absorber 56 as a whole is easily deformed to conform to the body surface.

[0116] When the highly compressed portions 51 are arranged along the virtual lattice of the example shown in Fig. 11 and Fig. 16, the dimensions of each highly compressed portion 51 can be appropriately determined, but the first highly compressed portion 51a has a diameter of 1 to 4 mm, the second highly compressed portion 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 portion 51a, and the third highly compressed portion 51c has the same size and shape as the second highly compressed portion 51b except that the major axis is oriented along the front-rear direction LD, and the shortest distance d4 between the adjacent first highly compressed portion 51a and second highly compressed portion 51b is preferably 1 to 2 mm, which not only improves the anti-reverse property and liquid diffusibility but also improves the ease of deformation of the absorbent body 56. The first interval 81d:second interval 82d is preferably in the range of 0.9:1.1 to 1.1:0.9, and it is particularly preferable that the first interval 81d and the second interval 82d are equal. The first gap 81d and the second gap 82d may be set to about 10 to 14 mm.

[0117] Furthermore, it is preferable for the above-mentioned virtual lattice to have a diagonal lattice pattern in which the first virtual straight lines 81 are inclined by 40 to 50 degrees clockwise relative to the front-to-back direction LD in a planar view, and the second virtual straight lines 82 are inclined by 40 to 50 degrees counterclockwise relative to the front-to-back direction LD in a planar view, as this not only improves the ease of deformation of the absorbent body 56 when worn, but also provides excellent liquid diffusion properties.

[0118] Table 2 shows a specific example of the arrangement of the highly compressed portion 51. [Table 2]

[0119] The absorbent element can be manufactured by a known method. For example, the absorbent element 50 having the highly compressed portion 51 can be manufactured by carrying out the following steps: a first step of forming an absorbent body 56 made by mixing and accumulating pulp fibers and highly absorbent polymer particles; a second step of forming a packaged body 50P by packaging the entire absorbent body 56 with a package sheet 58; and a third step of passing the packaged body 50P between an anvil roll 90 having a number of protrusions 91 arranged at intervals on the outer circumferential surface in the same pattern as the highly compressed portion 51 and a smooth roll 92 having a cylindrical surface (not having the protrusions 91) facing the anvil roll 90, as shown in FIG. 22, and pressing the portion of the packaged body 50P sandwiched between the many protrusions 91 of the anvil roll 90 and the smooth roll 92 to form the highly compressed portion 51. The highly compressed portion 51 may be formed while heating either one or both of the anvil roll 90 and the smooth roll 92, or may be formed 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 depth.

[0120] The dimensions, shape, and arrangement of the tip faces of the protrusions 91 may be, for example, similar to 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 may be equal to or less than the thickness of the highly compressed portions 51, and may 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 may be appropriately determined, and may be, for example, 0.2 to 0.4 MPa.

[0121] (packaging sheet) The packaging sheet 58 may be a liquid-permeable sheet such as crepe paper, nonwoven fabric, polylaminated nonwoven fabric, or a sheet with small holes. The nonwoven fabric used for the packaging sheet 58 is not particularly limited, but an SMS nonwoven fabric, SSMMS nonwoven fabric, or the like, in which at least one meltblown layer is sandwiched between a pair of spunbond layers on the front and back, may be suitably used. The material of the fibers is not particularly limited, and for example, polypropylene fibers, polyethylene / polypropylene bicomponent fibers, or the like may be used. The basis weight of the packaging sheet 58 may be determined as appropriate, but is preferably 5 to 40 g / m 2 , especially 10 to 30 g / m 2 It is preferable that the following be used.

[0122] 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 to 18 g / m 2 In addition, 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.

[0123] The average fiber length of the pulp constituting the crepe paper used in the packaging sheet 58 may be less than twice the average fiber length of all the pulp fibers constituting the absorbent body 56, but is preferably 1.5 to 3 times the average fiber length, which has the advantage of improving the material strength. The average fiber length of the pulp constituting the crepe paper used in the packaging sheet 58 is more preferably 1.5 to 3 times the average fiber length of all the pulp fibers constituting the absorbent body 56.

[0124] On the other hand, the crepe paper used for the packaging sheet 58 generally has a tensile breaking elongation of 20 to 35% in the front-rear direction LD and 4 to 8% (particularly 5 to 7%) in the width direction WD as specified in JIS P 8113:2006. When the packaging sheet 58 is made of such crepe paper, the crepe paper may break at the edges of the highly compressed portions 51 or between adjacent highly compressed portions 51 when the highly compressed portions 51 are formed. However, this can be reduced by having the outer shape of the highly compressed portions 51 have no inflection points or bending points, the diameter of the maximum inscribed circle inscribed in the outer shape of the highly compressed portions 51 is 2 to 5 mm, and the perimeter of the outer shape of the highly compressed portions 51 is 1 to 2.5 times the perimeter of the maximum inscribed circle inscribed in the outer shape of the highly compressed portions 51.

[0125] It is preferable that the MD direction of the packaging sheet 58 is configured along the front-rear direction LD because this makes manufacturing easier. In this case, the fiber orientation of the packaging sheet 58 is in the front-rear direction LD, and the dry tensile strength in the width direction WD is much weaker than the dry tensile strength in the front-rear direction LD. Therefore, if the dimension of the highly compressed portion 51 in the front-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 has a long shape in the front-rear direction LD), the packaging sheet 58 is likely to tear on both sides of the width direction WD. Therefore, it is preferable that the dimension of the highly compressed portion 51 in the front-rear direction LD is less than twice, particularly less than 1.5 times, the dimension of the highly compressed portion 51 in the width direction WD because the packaging sheet 58 is less likely to tear.

[0126] The packaging structure of the packaging sheet 58 can be determined as appropriate, but from the standpoint of ease of manufacture and prevention of leakage of superabsorbent polymer particles from the front and rear edges, it is preferable to wrap the sheet around the front and rear surfaces and both side surfaces of the absorbent body 56 in a cylindrical shape, as 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 parts and the overlapping parts of the protruding front and rear parts by a joining means such as a hot melt adhesive or material welding.

[0127] 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, because this doubles the crepe paper on the forming surface of the highly compressed portions 51, improving its strength and making it less likely to tear when the highly compressed portions 51 are formed.

[0128] The shape retention of the absorbent element 50 by the highly compressed portions 51 depends on the retention of the highly compressed portions 51 themselves, which in turn depends on the bonding 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 adhesives HM1 and HM2 than usual in order to adequately maintain the bonding strength between the packaging sheet 58 and the absorbent body 56 and the shape retention of the absorbent body 56 itself. Thus, the surface of the absorbent body 56 and the inner surface of the packaging sheet 58 should have a viscosity 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 two components are bonded together via hot melt adhesives HM1 and HM2.

[0129] 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. Such a structure can be manufactured by applying a first hot melt adhesive HM1 to almost the entire inner surface of an unfolded packaging sheet 58 facing the absorbent 56, as shown in FIG. 13, then arranging the absorbent 56 in the middle of the first hot melt adhesive HM1 of the packaging sheet 58 in the width direction WD, and bonding the back surface of the absorbent 56 to the packaging sheet 58 via the first hot melt adhesive HM1, and then applying a second hot melt adhesive HM2 to almost the entire surface of the absorbent 56, and then folding back the portions of the packaging sheet 58 that protrude on both sides of the absorbent 56 onto the surface of the absorbent 56, as shown in FIG. 14, and bonding the surface of the absorbent 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.

[0130] In order to reduce costs, the absorbent element 50 may not have any 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, etc., or may have other sheet layers on at least one of the front and back sides of the absorbent body 56.

[0131] <Method of manufacturing absorbent body> The absorbent body 56 can be manufactured by a known method. Fig. 25 is a schematic diagram of an example of an absorbent body manufacturing apparatus 100. In this absorbent body manufacturing apparatus, a pulp supplying section 111 that supplies a fiber material mainly containing pulp is provided upstream. The pulp supplying section 111 may include a defibrator, and a pulp sheet 110 is supplied to this defibrator.

[0132] When manufacturing an absorbent body 56 containing hardwood pulp fibers, a pulp sheet 110 containing hardwood pulp fibers is fed to a defibrator. In the defibrator, the pulp sheet 110 is defibrated into fibers by mechanical processing to obtain fluff pulp. The pulp sheet 110 may be in either a bale or roll form, but a roll form is preferred because it is easier to improve productivity.

[0133] Furthermore, there is no particular limitation on the device used for the mechanical treatment to defibrate the pulp sheet 110. A known defibrator used in the manufacture of absorbent articles such as disposable diapers can be used, and a defibrator that utilizes frictional force or shear force can be preferably used as the mechanical treatment. Examples of the type of defibrator include a hammer type defibrator, an impact type defibrator, a roll type defibrator, and a jet airflow type defibrator.

[0134] The fluff pulp obtained by defibration is supplied into the duct 112. A polymer particle introduction section 113 for supplying superabsorbent polymer particles may be provided in the middle of the duct 112. Thus, the pulp fibers 56f (fluff pulp) and the superabsorbent polymer particles 56p are mixed in the duct 112 and then supplied to the fiber stacking drum 115. A plurality of absorbent molds 115C are arranged on the outer circumferential surface of the fiber stacking drum 115 at intervals in the circumferential direction. As the fiber stacking drum 115 rotates, the absorbent molds 115C can sequentially receive the mixture of the pulp fibers 56f and the superabsorbent polymer particles 56p. The bottom surface of the absorbent mold 115C is made of a perforated plate or mesh plate, and the mixture of the pulp fibers and the superabsorbent polymer particles can be accumulated on the bottom surface of the absorbent mold 115C by sucking in the gas through the holes. In addition, the absorbent 56 can be supplied to a conveying means 116 such as a belt conveyor by discharging the gas through the holes. A negative pressure chamber and a positive pressure chamber are provided inside the fiber stacking drum 115, and each chamber is capable of sucking in and discharging gas, respectively.

[0135] A scuffing roll (or brush) 114 may be provided at a downstream position within the duct 112. The scuffing roll 114 scrapes off excess absorbent material that has been stacked, making the surface of the absorbent material accumulated in the absorbent mold 115C uniform. The absorbent 56 supplied to the conveying means 116 can be compressed in the thickness direction by compression means 117. The compression means 117 may be a pair of rolls as shown in FIG. 25, or a pair of pressing members that approach the absorbent 56 from both sides. The compression means 117 enhances the shape retention of the absorbent 56.

[0136] Further downstream, the absorbent body 56 is wrapped in a wrapping sheet 58 to become the absorbent element 50. The step of wrapping the absorbent body 56 in the wrapping sheet 58 can also be carried out by a known method.

[0137] When two layers of the absorbent body 56 are laminated, as shown in Fig. 26, a manufacturing apparatus 120 including single layer manufacturing units 101 and 102 for manufacturing each layer included in the absorbent body 56, in the illustrated example, an upper layer 56a and a lower layer 56b, respectively, can be used. Both single layer manufacturing units 101 and 102 have a similar configuration to manufacturing apparatus 100 (Fig. 25) for manufacturing a single layer absorbent body. The absorbent body layers 56a and 56b manufactured by the single layer manufacturing units 101 and 102, respectively, are stacked in the thickness direction, and then the entirety is further wrapped in a packaging sheet 58 to become an absorbent element.

[0138] (Rising Gathers) The rising gathers 60 have rising parts 68 that rise from the sides of the inner body 200, and these rising parts 68 come into contact with the wearer's groin, around the legs, and up to the buttocks to prevent side leakage. The rising gathers 60 can be omitted as necessary. In the illustrated example, the rising gathers 60 have a base side part 60B that rises obliquely toward the center in the width direction, and a tip side part 60A that rises obliquely from the middle part toward the outside in the width direction, but the present invention is not limited to this, and appropriate modifications are possible, such as ones that rise toward the center in the width direction as a whole.

[0139] More specifically, the rising gathers 60 in the illustrated example are formed by folding back a band-shaped gather sheet 62 having a length equal to the length of the inner body 200 in the front-rear direction at its tip in the width direction WD and folding it in two, and fixing a plurality of elongated gather elastic members 63 between the folded-back portion and the sheet in the vicinity of the folded-back portion in a stretched state along the longitudinal direction at intervals in the width direction WD. The base end portion (the end portion opposite the folded-back portion of the sheet in the width direction WD) of the rising gathers 60 located opposite the tip portion is a root portion 65 fixed to the side of the inner body 200, and the portion other than the root portion 65 is a main body portion 66 (the portion on the folded-back portion side) extending from the root portion 65. The main body portion 66 has a root side portion 60B extending toward the center in the width direction and a tip side portion 60A folded back at the tip of the root side portion 60B and extending outward in the width direction. And, while both front-to-rear end portions of the main body portion 66 are formed as fallen portions 67 fixed in a fallen state to the side surfaces of the top sheet 30, the front-to-rear intermediate portion located 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.

[0140] In the rising gathers 60 configured as described above, the rising portions 68 rise up so as to come into contact with the skin as shown by the arrows in Fig. 3 due to the contractile force of the gather elastic member 63. In particular, when the root 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 area and its vicinity, so that the rising gathers 60 come into contact with the leg circumference with a surface thereof, improving the fit. The root 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.

[0141] In the illustrated example of the rising gather 60, in a bent structure in which the main body portion 66 is composed of a root side portion 60B extending toward the center in the width direction and a tip side portion 60A folded back at the tip of the root side portion 60B and extending outward in the width direction, the tip side portion 60A and the root side portion 60B are joined in a fallen state at the fallen portion 67, and the root side portion 60B is joined in a fallen state to the top sheet 30. At least one of various hot melt adhesives applied by various methods and material welding means such as heat sealing and ultrasonic sealing can be used to join the opposing surfaces at the fallen portion 67. In this case, the joining of the root side portion 60B and the top sheet 30 and the joining of the tip side portion 60A and the root side portion 60B may be performed by the same means or by different means. For example, it is preferable that the base portion 60B and the top sheet 30 are joined by a hot melt adhesive, and the tip portion 60A and the base portion 60B are joined by material welding.

[0142] As the gathered sheet 62, a nonwoven fabric that is soft and has excellent uniformity and hiding properties, such as a spunbond nonwoven fabric (SS, SSS, etc.), an SMS nonwoven fabric (SMS, SSMMS, etc.), or a meltblown nonwoven fabric, and that is treated with silicone or the like to have a water repellent property as necessary, can be suitably used. In this case, the fiber basis weight of the nonwoven fabric is 10 to 30 g / m 2 Although not shown, a waterproof film may be interposed between the two folded gathered sheets 62.

[0143] The gathered elastic member 63 may 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 of the gathered elastic member 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 come into contact with the skin in a surface area within the range in which they are arranged. The gathered elastic members 63 may be arranged not only on the tip side but also on the base side.

[0144] In the rising portion 68 of the rising gather 60, at least one of hot melt adhesives applied by various application methods and material welding fixing means such as heat sealing and ultrasonic sealing can be used to bond the inner layer and the outer layer of the gather sheet 62 together and to fix the gather elastic member 63 sandwiched therebetween. Since bonding the entire surfaces of the inner layer and the outer layer of the gather sheet 62 together impairs flexibility, it is preferable that the parts other than the bonding parts of the gather elastic member 63 are not bonded or are weakly bonded. In the illustrated example, hot melt adhesive is applied only to the outer peripheral surface of the gather elastic member 63 by an application means such as a comb gun or a surwrap nozzle, and the gather elastic member 63 is sandwiched between the inner layer and the outer layer of the gather sheet 62, so that the gather elastic member 63 is fixed to the inner layer and the outer layer of the gather sheet 62 and the inner layer and the outer layer of the gather sheet 62 are fixed only by the hot melt adhesive applied to the outer peripheral surface of the gather elastic member 63.

[0145] Similarly, the fallen portion 67 can be fixed by at least one of a hot melt adhesive applied by various application methods and material welding such as heat sealing or ultrasonic sealing.

[0146] (Side flap) 1 to 4, 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 stretchable in the front-to-rear direction are formed in the 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 each other, 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.

[0147] The sheet material constituting the first sheet layer 71 and the second sheet layer 72 is not particularly limited, and an appropriate nonwoven fabric can be selected, such as a nonwoven fabric that can be used in the above-mentioned rising gathers 60 and the above-mentioned exterior bodies 12F and 12B. In the illustrated example, the first sheet layer 71 and the second sheet layer 72 are formed by extending the gather sheet 62 of the rising gathers 60, as described below. 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 interior body 200 in this case).

[0148] The side elastic members 73 are not particularly limited either, and can be elongated elastic members similar to the above-mentioned gathered elastic members 63. 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 arrangement interval of the side elastic members 73 is suitably 5 to 10 mm.

[0149] The side elastic member 73 is fixed to the first sheet layer 71 and the second sheet layer 72. For bonding the first sheet layer 71 and the second sheet layer 72 and for fixing the side elastic member 73 sandwiched therebetween, various application methods of hot melt adhesive HM and fixing means by material welding such as heat sealing and ultrasonic sealing can be used. If the bonding area of ​​the first sheet layer 71 and the second sheet layer 72 is large, flexibility is lost, so it is preferable that the parts other than the bonding parts of the side elastic member 73 are not bonded or are weakly bonded. In the illustrated example, the hot melt adhesive HM is applied only to the outer peripheral surface of the side elastic member 73 by an application means such as a comb gun or a surwrap nozzle, and the side elastic member 73 is sandwiched between the first sheet layer 71 and the second sheet layer 72, so that the side elastic member 73 is fixed to the first sheet layer 71 and the second sheet layer 72 and the first sheet layer 71 and the second sheet layer 72 are fixed only by the hot melt adhesive HM applied to the outer peripheral surface of the side elastic member 73.

[0150] 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 the folded back portions are fixed (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.

[0151] The side flaps 70 may be omitted.

[0152] <Manufacturing example of pulp sheet for absorbent body manufacturing> Using the materials shown in Table 1, pulp sheets No. 1 to 20 containing hardwood pulp fibers were produced according to the following procedure.

[0153] (Cooking process) (1) Hardwoods Acacia and eucalyptus were mixed in the mass ratio shown in Table 1, white liquor having a specified sulfidity was added, and cooking was carried out in a rotary autoclave at a liquor ratio of 6.0 (L / kg) and a maximum temperature of 170°C, to obtain unbleached hardwood kraft pulp with a kappa number of approximately 16. (2) Coniferous trees White liquor with a specified sulfidity was added to the cedar, and the mixture was cooked in a rotary autoclave at a liquor ratio of 6.0 (L / kg) and a maximum temperature of 170°C to obtain unbleached softwood kraft pulp with a kappa number of approximately 30.

[0154] (Cleaning process) After diluting the unbleached pulp to a pulp concentration of about 2%, No. 2 filter paper (manufactured by Advantec) was placed in a Buchner funnel and dehydrated to a pulp concentration of about 12%. The unbleached pulp was then sandwiched between square filter papers (manufactured by Advantec) and pressure was applied with a press machine to dehydrate to a pulp concentration of 33%. This washing process was carried out twice.

[0155] (bleaching process) (1) Hardwoods Unbleached kraft pulp was bleached with ozone gas of 8.1% concentration at 45°C for about 2 minutes. For the ozone bleaching, ozone gas from a laboratory ozone generator, PSA Ozonizer SGA-01A-PSA4 manufactured by Sumitomo Precision Products Co., Ltd., was used. The pulp after ozone bleaching was further bleached with chlorine dioxide at 70°C with a chlorine dioxide addition rate of 1.5% and a pulp concentration of 10% by mass to obtain bleached hardwood kraft pulp. Between each bleaching process, the pulp was diluted to a concentration of about 2%, and then a dilution washing process was carried out twice, in which No. 2 filter paper (manufactured by ADVANTEC) was placed in a Buchner funnel and the pulp concentration was dehydrated to about 12%. (2) Coniferous trees The unbleached kraft pulp was bleached with chlorine dioxide at a chlorine dioxide addition rate of 1.5% and a pulp concentration of 10% by mass at 70°C for 30 minutes. Then, alkaline hydrogen peroxide bleaching was performed at an alkali addition rate of 1%, a hydrogen peroxide addition rate of 0.3%, a pulp concentration of 10% by mass at 70°C for 120 minutes. Then, an alkali treatment was performed at a sodium hydroxide addition rate of 0.2%, a pulp concentration of 10% by mass at 70°C for 120 minutes. Then, chlorine dioxide bleaching was performed at a chlorine dioxide addition rate of 0.3%, a pulp concentration of 10% by mass at 70°C for 150 minutes to obtain softwood bleached kraft pulp. Between each bleaching step, the pulp was diluted to a concentration of about 2%, and then a dilution washing step was performed twice, in which No. 2 filter paper (manufactured by ADVANTEC) was placed in a Buchner funnel and the pulp concentration was dehydrated to about 12%.

[0156] (Paper making process) The obtained hardwood kraft pulp and softwood kraft pulp were not beaten but diluted to a consistency of about 2% to adjust the blending ratios shown in Table 2. The adjusted pulp slurry was then used to make a semi-automatic sheet machine (manufactured by Kumagai Riki Kogyo Co., Ltd.) to a basis weight of 800 g / m 2 A hand-made sheet (pulp sheet for fluff pulp) was prepared so that the above-mentioned

[0157] <Production of absorbent articles> Using each pulp sheet, an absorbent body was produced using an apparatus as shown in Fig. 25. The amount of superabsorbent polymer added to the fluff pulp was 9.3 g per 7.7 g of fluff pulp. Using the obtained absorbent body, a disposable diaper (tape type, L size) was produced without providing the above-mentioned highly compressed portion 51.

[0158] <Measurement of fiber length and fiber width of pulp fibers> The fiber length and fiber width of each hardwood unbleached kraft pulp after the cooking and washing processes were measured. The fiber length and fiber width were measured using a fiber length measuring instrument "VALMET FS5" manufactured by Valmet in accordance with JIS-P8226:2011 (ISO16065-2:2007) "Pulp - Fiber length measurement method by optical automatic analysis". The fiber analyzer "VALMET FS5" is a device that can measure the length and width of pulp fibers by image analysis when diluted pulp fibers pass through a measurement cell inside the fiber analyzer. From the measured values ​​obtained, the mass ratio of pulp fibers with a fiber length of 0.5 mm or more and less than 1.1 mm, and the mass ratio of pulp fibers with a fiber width of 10 μm or more and less than 35 μm were calculated. In addition, the average fiber length and standard deviation σ were calculated when the pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm were measured at 0.02 mm intervals (classification width of 0.02 mm), and the average fiber width and standard deviation σ were calculated when the pulp fibers having a fiber width of 10 μm or more and less than 35 μm were measured at 1 μm intervals (classification width of 1 μm). The average values ​​(average fiber length and average fiber width values) are arithmetic means. The standard deviation was calculated from n=10,000 or more measurements using a fiber analyzer. The calculation results are shown in Table 3.

[0159] [Table 3]

[0160] <Evaluation> The evaluation was carried out as follows. The evaluation results are shown in Table 4.

[0161] (density) The density of the fluff pulp pulp sheet in each example was measured in accordance with "Paper and paperboard - Test methods for thickness, density and specific volume" described in JIS-P8118 (2014).

[0162] (Calculation of specific burst strength) The burst strength of each fluff pulp sheet is calculated by dividing the burst strength [kPa] measured in accordance with JIS-P8131 (2009) by the basis weight [kPa m2 / g].

[0163] (Defibrilability evaluation) The defibrability of each fluff pulp pulp sheet was evaluated based on the specific burst strength. The evaluation criteria were 5 levels as follows. When the evaluation was A, B, C, or D, the defibrability of the fluff pulp pulp sheet was good, and among these, the defibrability was excellent in the case of A. Also, D was slightly inferior, but still at a level that was not problematic in practical use. A: Specific burst strength is 1.2 kPa m 2 / g or more 1.5kPa m 2 / g or less. B: Specific burst strength is 1.6 kPa m 2 / g or 1.1 kPa m 2 / g. C: Specific burst strength is 1.7 kPa m 2 / g or 1.0 kPa m 2 / g. D: Specific burst strength is 1.8 kPa m 2 / g or 0.9 kPa m 2 / g. E: Specific burst strength is 1.9 kPa m 2 / g or more or 0.8 kPa m 2 / g or less.

[0164] (Klemm water absorbency measurement) The Klemm water absorbency of each fluff pulp sheet was measured in accordance with "Paper and paperboard - Water absorbency test method - Klemm method" described in JIS-P8141 (2004). More specifically, 2 For each fluff pulp pulp sheet, the height [mm] was measured 1 minute after the start of the measurement, and the water absorption rate [mm / min] from 1 to 2 minutes after the start of the measurement was calculated based on the heights [mm] 1 minute and 2 minutes after the start of the measurement.

[0165] (Water absorption evaluation) Based on the height value at 1 minute after the start of the measurement, the water absorption amount (absorbency performance) of the flap pulp sheet was evaluated according to the following criteria. A: The height measured one minute after the start of the Klemm absorbency measurement is 29 mm or more and 40 mm or less. B: The height measured one minute after the start of the Klemm absorbency measurement is 27 mm or more and less than 29 mm. C: The height measured one minute after the start of the Klemm water absorbency measurement is 25 mm or more and less than 27 mm. D: The height at 1 minute after the start of measurement in the Klemm water absorbency test is less than 25 mm.

[0166] (Water absorption speed evaluation) Based on the water absorption rate value between 1 minute and 2 minutes after the start of the measurement, the water absorption rate of the flap pulp sheet was evaluated according to the following criteria. A: The water absorption rate during the period from 1 to 2 minutes after the start of the Klemm water absorption measurement is 9 mm / min or more. B: The water absorption rate during the period from 1 minute to 2 minutes after the start of the Klemm water absorption measurement is 7 mm / min or more and less than 9 m / min. C: The water absorption rate during the period from 1 minute to 2 minutes after the start of the Klemm water absorption measurement is 5 mm / min or more and less than 7 mm / min. D: The water absorption rate during the period from 1 minute to 2 minutes after the start of measurement in the Klemm water absorption test is more than 3 mm / s and less than 5 mm / s. E: The water absorption rate during the period from 1 minute to 2 minutes after the start of the Klemm water absorption measurement is 3 mm / min or less.

[0167] (Evaluation of workability during fluff pulp production) The workability of fluff pulp during production is 200 g / m2 2 The fluff pulp sheets of each example were cut into 2 cm x 2 cm pieces and crushed in a commercially available mixer (Tescom Co., Ltd., Mixer TM856), and the amount of paper dust generated during crushing was examined and evaluated. The amount of accumulated paper dust generated during crushing increased from E to A. Evaluation was based on the following five-level scale. Evaluations of A, B, C, and D indicate good workability. A: When the pulp sheet is crushed, paper dust flies around and there is a small amount of pulp accumulated on the mixer walls. B: When the pulp sheet is crushed, paper dust is thrown around and some pulp is piled up on the mixer walls. C: When the pulp sheet is crushed, paper dust is thrown around and a small amount of pulp is piled up on the mixer walls. D: When the pulp sheet is crushed, paper dust flies around and some pulp accumulates on the mixer walls, but this is not a problem. E: When the pulp sheet was crushed, paper dust flew about and a large amount of pulp accumulated on the mixer walls, making it unsuitable for practical use.

[0168] (Evaluation of skin rash prevention for absorbent articles) A total of 220 monitors were asked to use 10 of each of the disposable diapers No. 1 to No. 22, which were prepared as described above for each example. That is, an evaluation was carried out by 10 monitors for each example of disposable diaper. The number of diapers that caused a rash was then evaluated as a percentage. The evaluation was made on a 5-point scale as follows. If the evaluation was A, B, C, or D, it means that the effect of suppressing skin rash was better than that of No. 20, which has the same composition as the existing product. A: The incidence of rashes is better than No. 20. B: The incidence of rashes is slightly better than No. 20. C: The incidence of rashes is slightly better than No. 20. D: The incidence of rashes is slightly better than No. 20, and it is usable. E: The incidence of rashes is equivalent to that of No. 20 and is at the same level as existing products. The effect of suppressing rash is related to the effect of suppressing return of the absorbent body and the absorption capacity of the absorbent body.

[0169] [Table 4]

[0170] As shown in Tables 3 and 4, Nos. 1 to 19, which contain hardwood pulp fibers and softwood pulp fibers, and have a pulp fiber ratio of 42.6% or more with a fiber length of 0.5 mm or more and less than 1.1 mm in the total pulp fibers, and a pulp fiber ratio of 90.6% or more with a fiber width of 10 μm or more and less than 35 μm, showed particularly good results in terms of defibration ability, workability during the production of fluff pulp, and rash prevention effect in absorbent articles.

[0171] <Effectiveness Confirmation Test 1> Pants-type disposable diaper samples (having the same structure as in Figs. 1 to 6) equipped with absorbent elements of the various conditions shown in Table 5 were prepared, and measurements of the thickness of the absorbent elements, a backflow test under pressure, measurements of the diffusion area, an absorbent strength test, and a polymer shedding test were performed. Note that 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 Table 5 were measured values ​​of the material before the highly compressed portion was formed.

[0172] The dimensions of each part of Samples 1 and 3 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 distance 82d: 12.63mm Intersection angle between the first virtual line 81 and the second virtual line 82: 90 degrees

[0173] In Samples 1 and 3, the highly compressed portion was formed over the entire surface of the absorbent element at a pressure of 0.4 MPa. Samples 2 and 4 were comparative examples that did not have highly compressed portions. Conditions other than the specifications shown in Table 5 were the same for each sample.

[0174] (Reverse test under pressure) This test was carried out using a blue test solution prepared by dissolving approximately 5 g of Kiriya Co.'s Brilliant Blue FCF (packaging: powder) in approximately 300 ml of artificial urine, and was carried out according to the following procedure. (1) After cutting the side seal 12A of the sample and opening the front body F and the back body B, the sample was placed on a horizontally placed flat plate with the surface (the surface having the depression of the highly compressed portion) facing up, and the four corners of the sample were fixed to the flat plate with adhesive tape so that the inner body 200 was fixed in a flat, unfolded state. (2) An injection tube (consisting of an acrylic cylindrical portion with an inner diameter of 23 mm, an outer diameter of 25 mm, and a height of 100 mm, and a square flange portion extending around the cylindrical portion and measuring 100 mm in length, 100 mm in width, and 2 mm in thickness) was placed on the center of the absorbent on the surface of the sample (the center in the width direction and the center in the front-to-back direction) and held vertically. (3) Using a measuring cylinder, pour 50 cm of the above blue test liquid into the upper opening of the injection tube. 3 7cm 3 The artificial urine was injected at a rate of 1 / sec, and the injection tube was removed after a wait from the start of injection until the artificial urine disappeared from the sample surface (was completely absorbed). (4) The injection tube was removed and the mixture was left for 30 minutes. (5) Following (4) above, steps (2) to (4) above were repeated. (6) Following (5) above, steps (2) and (3) above were carried out again. (7) 20 minutes after the artificial urine from the third injection in (6) above was completely absorbed, a 5 kg weight was placed on the injection site and left for 10 minutes. The weight was a square with a flat bottom measuring 100 mm long x 100 mm wide, and was placed on the surface of the sample so that the length and width of the weight were aligned with the front-rear and width directions of the sample and the center of the weight was located above the center of the absorbent body. (8) The weight (g) of 30 sheets of ADVANTEC's qualitative filter paper No. 2 (100 mm x 100 mm square) was measured to three decimal places using an electronic balance. (9) Following (7) above, 30 sheets of the above filter papers were placed between the weight and the sample surface with their centers and orientations aligned, and after 20 seconds, all the filter papers were removed and their weights (g) were measured to two decimal places. The weight measured before absorption in (5) above was subtracted from the weight measured after absorption to determine the amount of backflow.

[0175] (Measurement of diffusion area) Following the above-mentioned pressure reversal test, the sample was fixed onto a horizontally placed flat plate, a ruler was placed next to it, and still images of the sample and ruler were taken from directly above. The captured image data was then read into the image analysis software "Fiji" (Fiji Is Just ImageJ), and the area of ​​the blue portion on the sample surface was measured using the following procedure. (1) Start Fiji, select "File" and then "Open", and load the image to be measured. (2) Select the “Straight” icon and align it with the two points on the ruler scale in the image. (3) Select “Analyze” and then “Set Scale,” and enter the actual distance between the two points determined in (2) above (read from the ruler scale) into “Known distance,” and enter the unit into “Unit of length.” (4) Select "Image," "Type," and then "8-bit" to convert the image to 8-bit. (5) Select "Image," "Adjust," and "Threshold" in that order to display the Threshold selection screen, set the Threshold to 150~210 (Default Red), and check "Dark background" and "Don't reset range." (6) Select “Analize” and “Set Measurements”, check “Area”, “Mean gray value”, “Min & Max gray value”, and “Limit to threshold”, and select OK. (7) Select “Polygon selections” and circle the liquid diffusion area displayed in red in (5) above. (8) Select "Analyze" and then "Measure" to display the "Results", and set the "Area" item to the diffusion area (set "Unit of length" to cm, and the unit of area is cm 2 (It was decided that.)

[0176] (Absorbent strength test) (1) After cutting the side seal 12A of the sample and opening the front body F and the back body B, the sample was placed on a horizontally placed flat plate with the surface (the surface having the depression of the highly compressed portion) facing up, and the four corners of the sample were fixed to the flat plate with adhesive tape so that the inner body 200 was fixed in a flat, unfolded state. (2) An injection tube (consisting of an acrylic cylindrical section with an inner diameter of 23 mm, an outer diameter of 25 mm, and a height of 100 mm, and a square flange section extending around the cylindrical section and measuring 100 mm in length, 100 mm in width, and 2 mm in thickness) was placed at the center of the absorbent body (the center in the width direction and the center in the front-to-back direction) and 100 mm behind that, and held vertically. (3) Using a measuring cylinder, pour 90 cm of the above blue test liquid into the upper opening of the injection tube. 3 7cm 3 The artificial urine was injected at a rate of 1000 mg / sec. A wait was then allowed from the start of injection until all the artificial urine had disappeared from the surface of the sample (was completely absorbed), at which point a 300 g weight was placed on the flange of each injection tube, and a load was applied evenly to the flange. (4) After placing the weights in (3) above and leaving them for 5 minutes, remove the two weights and the rear injection tube, and pour 90 cm of the above blue test liquid into the upper opening of the central injection tube using a measuring cylinder. 3 7cm 3 The artificial urine was injected at a rate of 100 µg / sec. A wait was then allowed from the start of injection until all the artificial urine had disappeared from the surface of the sample (was completely absorbed), at which point a 300 g weight was placed on the flange of the central injection tube, and a load was applied evenly to the flange. (5) After the weight in (4) was placed and left for 5 minutes, the sample was removed from the flat plate and attached to the rotating plate 303 of the hammering tester 300 described below, and hammering was performed repeatedly at 5 second intervals. Note that in the initial state in which the rotating plate 303 faces vertically downward, the outer surface of the front exterior body 12F of the sample was attached to the hook member 303F of the rotating plate 303 so that the front-to-rear direction of the sample 320 was aligned with the up-down direction. (6) During the striking in (5) above, the tester visually inspected the shape of the absorbent body of sample 320 from the front of striking surface 301S, and if he recognized that a crack had occurred in the absorbent body, he stopped striking after each strike and measured the width of the crack with a ruler. The number of strikes required until the width of the crack became 3 cm was recorded as the strength of the absorbent body.

[0177] (Driven test machine) 27 and 28 show a hammering tester 300. This hammering tester 300 comprises a support 310 made of a rectangular parallelepiped frame installed on the floor, a light box 301 attached to the vertical center of a back part 311 of this support 310, a first rotating shaft 302 extending in a substantially horizontal direction and spaced apart above the light box 301 on the back part 311, one end of which is fixed to the first rotating shaft 302 and supported so as to be freely rotatable forward and backward between a state facing vertically downward and a state facing horizontally by rotating from there toward the front side. The light box 301 has a flat rotating plate 303, a second rotating shaft 304 provided concentrically with a center line obtained by extending the rotation center line of the first rotating shaft 302 in the horizontal direction, a sample gripping arm 305 extending radially from the second rotating shaft 304 and supported by the second rotating shaft 304 so as to be rotatable forward and backward, and a drive source (servo motor) 306 for rotating the sample gripping arm 305 forward and backward between a state in which the arm faces vertically downward and a state in which the arm faces substantially horizontally after being rotated from the state toward the front. The light box 301 has a transparent striking surface 301S on the front side, and light from an internal light (white LED) 301L passes through the striking surface 301S and is irradiated in the forward direction. In addition, the rotating plate 303 has a hook member 303F of a mechanical fastener attached over almost the entire surface that is the front side in the initial state facing vertically downward, and the outer surface of the sample 320 can be attached to this hook member 303F. The tip of the sample gripping arm 305 has a clamp unit 307 that grips the lower end of the sample 320 hanging down from the rotating plate 303 facing vertically downward, and while maintaining this state, rotates the lower end of the sample 320 to the front side and rotates to a substantially horizontal direction, and then releases the grip, and a driving source (not shown) for driving the clamp unit. Reference numeral 307C denotes a pair of gripping units for gripping the sample 320 from both the front and back sides of the lower end of the sample 320.

[0178] In the striking tester 300, after the sample 320 is attached to the rotating plate, in the initial state where no external force is applied, the sample 320 and the rotating plate 303 face almost vertically downward as shown by the solid line in Fig. 27, and the outer surface of the sample 320 is in contact with the striking surface 301S of the light box 301. The sample gripping arm 305 faces almost vertically downward, and the clamp part 307 at the tip is in an open state. When the test operation is started, the clamp part 307 automatically closes and grips the lower end of the sample 320, as shown by the arrow and the two-dot chain line in the enlarged portion of Fig. 27, and while maintaining this state, the sample gripping arm 305 rotates until it becomes almost horizontal on the front side as shown by the arrow and the two-dot chain line in Fig. 27, so that the lower end of the sample 320 also faces almost in the same direction. Next, as shown by the arrow and the two-dot chain line in the enlarged portion of FIG. 27, the clamping part 307 automatically opens, and the sample 320 and the rotating plate 303 lose the restraining external force, and rotate freely around the first rotating shaft 302 by their own weight, and the back surface of the sample 320 is struck against the striking surface 301S of the light box 301. After that, the sample gripping arm 305 returns to the initial state. During the test operation, the striking operation of the sample 320 (grasping, rotating, releasing, and striking) is repeated at set time intervals. By stopping the test operation, the sample 320 and the rotating plate 303 are in a state of facing almost vertically downward, and the sample 320 stops in a posture along the striking surface 301S of the light box 301. Here, a tester facing the front of the sample 320 can visually confirm the shape of the absorber by the illumination light from the light box 301 that passes through the sample 320 (difference in the amount of transmission). In particular, the external shape of the absorbent body that has absorbed the above-mentioned blue test liquid can be easily recognized visually.

[0179] (Polymer shedding test) (1) After cutting the side seal 12A of the sample to open the front body F and the back body B, the rear end of the inner body was cut along the rear end of the absorbent body to expose the rear end of the absorbent body. Note that the rear outer body 12B of this sample had a folded portion 12r that covered the inner body 200 up to the end on the waist opening WO side, so this folded portion 12r was peeled off and cut off using cold spray. (2) In the initial state where the rotating plate 303 of the striking tester 300 faces vertically downward, the outer surface of the front exterior body 12F of the sample was attached to the hook member 303F of the rotating plate 303 so that the front-rear direction of the sample 320 was aligned with the up-down direction. In addition, a collection tray (not shown) for receiving the superabsorbent polymer particles was placed at a position 10 cm below the striking surface 301S. Thereafter, striking was repeated 30 times at 5-second intervals. (3) After the impact in (2) above, the weight of the fallen polymer in the collection tray was measured and recorded as the amount of fallen polymer.

[0180] The test results are shown in Table 5.

[0181] [Table 5]

[0182] Sample 1, which has an absorbent body containing hardwood pulp fibers and has a highly compressed portion formed in the absorbent element, had a higher absorbent strength than Sample 2, which is the same except that it does not have a highly compressed portion, and also had the same level of absorbent strength as Sample 3, which has an absorbent body made only of softwood pulp fibers. The diffusion area of ​​Sample 1 was significantly higher than Sample 2 and was at the same level as Sample 3, which has an absorbent body made only of softwood pulp fibers. Furthermore, Sample 1 not only had a smaller amount of backflow than Sample 2, but also had a significantly smaller amount than all the samples, which was a noteworthy result. Sample 1 also had a smaller amount of polymer shed than Sample 2, and was at the same level as Sample 3, which had an absorbent body made only of softwood pulp fibers. As can be seen from the comparison of Samples 1 and 2 and the comparison of Samples 3 and 4, the thickness of the absorbent element was reduced by the formation of the highly compressed portion, and as can be seen from the comparison of Samples 1 and 3, the thickness of the absorbent element was further reduced by the inclusion of hardwood pulp fibers.

[0183] <Explanation of terms used in the specification> As used herein, the following terms have the following meanings unless otherwise specified in the specification.

[0184] The "front-rear direction" refers to the direction indicated by the symbol LD in the drawing (longitudinal direction), and the "width direction" refers to the direction indicated by the symbol WD in the drawing (left-right direction), with the front-rear direction and the width direction being perpendicular to each other.

[0185] "Front side" means the side closest to the wearer's skin when worn, and "back side" means the side away from the wearer's skin when worn.

[0186] "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.

[0187] "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.

[0188] "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.

[0189] "Gel strength" is measured as follows. 1.0g of superabsorbent polymer is added to 49.0g of artificial urine and stirred with a stirrer. The resulting gel is left in a thermo-hygrostat at 40℃ x 60%RH for 3 hours, then returned to room temperature and the gel strength is measured with a card meter (I.techno Engineering: Curdmeter-MAX ME-500).

[0190] - "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, a sample template (100mm x 100mm) is used to cut out a sample measuring 100mm x 100mm. The weight of the sample is measured and multiplied by 100 to calculate the weight per square meter, which is the basis weight.

[0191] The "thickness" of thick members such as the absorbent 56 and the absorbent element 50 is measured using a thickness gauge (Peacock, dial thickness gauge, model H (measurement range: 0-10 mm, gauge head: circular pressure plane with a diameter of 10 mm, measurement force: approximately 1.7 N, pressure: approximately 21.7 KPa)) manufactured by Ozaki Manufacturing Co., Ltd., with the test member and the thickness gauge held 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 in which the inscribed circle inscribed in the outer shape of the non-highly compressed portion 52 is maximized are selected, and the thickness measured by aligning the center of the inscribed circle of the region with the center of the gauge head of the thickness gauge is regarded as the thickness of the absorbent element 50 (non-highly compressed portion 52).

[0192] 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).

[0193] The "depth" of the highly compressed portion 51 is measured using a one-shot 3D measuring macroscope VR-3200 manufactured by Keyence Corporation or an equivalent device, an observation application "VR-H2V" and an analysis application "VR-H2A", or software equivalent thereto. In principle, the magnification during measurement is 12 times, and the field of view area is 24 mm x 18 mm, but the magnification and field of view area can be changed depending on the size of the highly compressed portion 51. To measure the specific depth, the observation application is started, a sample is placed on the stage of the microscope so that the highly compressed portion 51 to be measured is positioned within the field of view, and the "measure" button is pressed. Next, the analysis application is executed, and the measured 3D information is analyzed. The analysis procedure is described below with reference to FIG. 23. That is, the above analysis application is used to obtain a depth (measured cross-sectional curve) profile at a line segment Q1 passing through the center (center of gravity if not circular) of one highly compressed portion 51 in the image portion (XY portion in the figure) shown in a planar viewpoint. From the cross-sectional curve of this depth profile, surface roughness components with wavelengths shorter than λc:800 μm (where λc is the “filter that defines the boundary between the roughness component and the waviness component” described in “3.1.1.2” of JIS-B0601) are removed by a low-pass filter, and the “contour curve Q2” of the image part (XZ part in the figure) shown from the cross-sectional viewpoint is obtained. The positions where the curve is almost flat or the positions where the curve is convex upward and strongest are taken as two boundary points P1 and P2, and the minimum value of the height of the range sandwiched between these boundary points P1 and P2 is obtained. Furthermore, the average value of the height values ​​of the boundary points P1 and P2 is taken as the maximum height. The depth of the highly compressed portion 51 can be obtained by subtracting the minimum height value from the maximum height. The two boundary points P1 and P2 are selected by visual inspection. In addition, the image of the highly compressed portion 51 during the measurement from a planar viewpoint may be used as a reference for the selection. The above measurements are carried out for any 10 highly compressed portions 51 designed to have the same dimensions and shape, and the results are recorded as an average value.

[0194] The dimensions of the highly compressed portion 51, such as the diameter and spacing, are measured using a one-shot 3D measuring macroscope VR-3200 manufactured by Keyence Corporation or an equivalent device, the observation application "VR-H2V" and the analysis application "VR-H2A", or their equivalent software. In principle, the magnification during measurement is 12 times, and the field of view area is 24 mm x 18 mm, but the magnification and field of view area can be changed depending on the size of the highly compressed portion 51. To measure the dimensions, start the observation application, place a sample on the microscope stage so that the highly compressed portion 51 to be measured is positioned within the field of view, and press the "Measure" button. Next, run the analysis application and analyze the measured 3D information. The procedure for analyzing the diameter of the highly compressed portion 51 is described below with reference to FIG. 23. That is, using the above-mentioned analysis application, a depth (measured cross-sectional curve) profile is obtained at a line segment Q1 that passes through the target highly compressed portion 51 along an arbitrary diameter direction in an image portion (XY portion in the figure) shown from a planar viewpoint. From the cross-sectional curve of this depth profile, surface roughness components with wavelengths shorter than λc: 800 μm (where λc is the “filter that defines the boundary between the roughness component and the waviness component” described in JIS-B0601 “3.1.1.2”) are removed by a low-pass filter. The “contour curve Q2” of the image portion (XZ portion in the figure) shown from a cross-sectional viewpoint is obtained by removing surface roughness components with wavelengths shorter than λc: 800 μm (where λc is the “filter that defines the boundary between the roughness component and the waviness component” described in JIS-B0601 “3.1.1.2”). The intersection points P3 and P4 are the intersection points with a straight line Q3 that is parallel to the X-axis and located +0.25 mm from the lowest point 51L, and the distance X1 in the X-axis direction of these intersection points P3 and P4 is the diameter of the highly compressed portion 51. The above measurements are performed on any 10 highly compressed portions 51 designed to have the same dimensions and shape, and the results are the average value. The procedure for analyzing the interval between adjacent highly compressed portions 51 will be described with reference to Fig. 23 as follows. That is, using the above analysis application, a depth (measured cross-sectional curve) profile is obtained at a line segment Q1 that passes through two adjacent highly compressed portions 51 along the direction of the target interval in an image portion shown in a plan view. From the cross-sectional curve of this depth profile, surface roughness components with wavelengths shorter than λc: 800μm (where λc is the "filter that defines the boundary between roughness components and waviness components" described in JIS-B0601 "3.1.1.2") are removed by a low-pass filter. The intersections of the "contour curve Q2" of the image portion shown in a cross-sectional view (XZ portion in the figure) with a straight line Q3 parallel to the X-axis located +0.25mm from the lowest point 51L are defined as P3, P4, P5, and P6, and the distance X2 in the X-axis direction between the two adjacent intersections P4 and P5 in the middle is defined as the interval between the highly compressed portions 51. The above measurements are carried out for any five pairs of adjacent highly compressed portions 51 designed to have the same dimensions and shape, and the results are recorded as an average value.

[0195] 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 The measurement is performed automatically under the following conditions.

[0196] The "area" of the highly compressed portion 51 is measured using a one-shot 3D measuring macroscope VR-3200 manufactured by Keyence Corporation or an equivalent device, and the observation application "VR-H2V" and analysis application "VR-H2A", or software equivalent thereto. In principle, the magnification during measurement is 12 times, and the field of view area is 24 mm x 18 mm, but the magnification and field of view area can be changed depending on the size of the highly compressed portion 51. Specifically, when measuring the area, the above observation application is started, a sample is placed on the stage of the microscope so that the highly compressed portion 51 to be measured is positioned within the field of view, and the "Measure" button is pressed. Next, the above analysis application is executed, and in order to analyze the measured 3D information, the "Volume / Area" button is pressed to move to the volume / area measurement screen. In the volume / area measurement screen, the "Concave" button is pressed, the "Set measurement area" button is pressed, and then the "Minimum height" button is pressed from the "Auxiliary tool 2" to specify an area to include one highly compressed portion 51 of interest, and the lowest point within the displayed area is selected. Next, select "Auto Extraction (Level)" from "Element Tools", then specify the lowest point as the reference point, set the intersection height to +0.25 mm, and press the "OK" button. Return to the volume / area measurement screen, and the value displayed as the area of ​​the portion from the lowest point to a height of 0.25 mm within the specified region is taken as the area of ​​the highly compressed portion 51. The above measurements are carried out for any five highly compressed portions 51 designed with the same dimensions and shape, and the result is taken as the average value.

[0197] "Area ratio" means the ratio of the area of ​​the target part per unit area, and is expressed as a percentage by dividing the total area of ​​the target part (e.g., the highly compressed part 51) in the entire target area (e.g., the back surface of the absorbent element 50) by the area of ​​the target area. When calculating the area ratio of the highly compressed part 51, a rectangular area circumscribing all of the highly compressed parts 51 is used as the target area, and the total area of ​​the highly compressed parts 51 is calculated from the area of ​​the highly compressed parts 51 described below. In other words, when five or more highly compressed parts 51 designed to have the same dimensions and shape are provided, the areas of all the highly compressed parts 51 in the design are the average values ​​measured by the above-mentioned method for measuring the area of ​​the highly compressed parts 51. On the other hand, when the dimensions and shape of the highly compressed parts 51 are irregular, or when there are less than five highly compressed parts 51 designed to have the same dimensions and shape, the areas of all the highly compressed parts 51 are measured one by one by the above-mentioned method for measuring the area of ​​the highly compressed parts 51 (the average value is not calculated).

[0198] "Water absorption" is measured in accordance with JIS K7223-1996 "Test method for water absorption of superabsorbent polymers."

[0199] "Water absorption rate" is the "time to the end point" when 2g of superabsorbent polymer and 50g of physiological saline are used and the JIS K7224-1996 "Test method for water absorption rate of superabsorbent polymers" is performed.

[0200] "Unfolded state" means a flat, unfolded state without contraction (including any contraction, such as contraction due to elastic members) or sagging.

[0201] *Unless otherwise specified, the dimensions of each part refer to the dimensions in the unfolded state, not in the natural length state.

[0202] If no specification is given regarding the environmental conditions for a test or measurement, the test or measurement shall be carried out in a test room or equipment under standard conditions (the test location shall be a temperature of 23±1°C and a relative humidity of 50±2%). [Industrial Applicability]

[0203] The present invention can be used in general absorbent articles having an absorbent core, including disposable diapers such as pants-type disposable diapers, tape-type disposable diapers, and pad-type disposable diapers, as well as sanitary napkins and diapers for pets. [Explanation of symbols]

[0204] 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...middle 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, 56f...pulp fiber, 56p...highly absorbent polymer particles, 56L...low basis weight portion, 58...packaging sheet, 60...rising gathers, 60A...tip side portion, 60B...attachment base side portion, 62...gathered sheet, 63...gathered elastic member, 67...falling portion, 68...rising 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 to back 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, The absorbent element includes 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 formed by mixing and accumulating pulp fibers including hardwood pulp fibers and highly absorbent polymer particles, The absorbent element has a plurality of highly compressed portions compressed in a thickness direction so as to be recessed from at least one of the front and rear surfaces of the absorbent element into the absorbent body, the highly compressed portions being spaced apart from one another; a portion other than the highly compressed portions in an arrangement region of the plurality of highly compressed portions is a non-highly compressed portion that is thicker and has a lower density than the highly compressed portions, The density of the absorbent body in the highly compressed portion is 60,000 to 250,000 g / m ３ and The area of ​​each of the highly compressed parts is 2 to 200 mm ２ That is, An absorbent article characterized by:

2. It has a crotch area, The absorbent element includes 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 formed by mixing and accumulating pulp fibers including hardwood pulp fibers and highly absorbent polymer particles, The absorbent element has a plurality of highly compressed portions compressed in a thickness direction so as to be recessed from at least one of the front and rear surfaces of the absorbent element into the absorbent body, the highly compressed portions being spaced apart from one another; a portion other than the highly compressed portions in an arrangement region of the plurality of highly compressed portions is a non-highly compressed portion that is thicker and has a lower density than the highly compressed portions, Each of the plurality of highly compressed portions has a shortest distance to the nearest other highly compressed portion of 1 to 4 mm. An absorbent article characterized by:

3. an area ratio of the highly compressed portions in an arrangement region of the plurality of highly compressed portions is 10% to 35%; The diameter of the maximum inscribed circle inscribed in the outer shape of the non-highly compressed portion is 30 mm or less.

3. The absorbent article according to claim 1 or 2.

4. The highly compressed portion has an outer shape that does not have an inflection point or a bending point, and the diameter of the maximum inscribed circle inscribed in the outer shape of the highly compressed portion is 1 to 10 mm, and the circumferential length of the outer shape of the highly compressed portion is 1 to 15 times the circumferential length of the maximum inscribed circle inscribed in the outer shape of the highly compressed portion. The absorbent article according to claim 3.

5. In the arrangement region of the plurality of 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 a minimum virtual rectangle having vertices at intersections of the first virtual line and the second virtual line is defined, the highly compressed portion includes a first highly compressed portion disposed at an intersection of the first imaginary line and the second imaginary line, a second highly compressed portion disposed between adjacent first highly compressed portions on the first imaginary line and between adjacent first highly compressed portions on the second imaginary line, and a third highly compressed portion disposed at an intersection of diagonals of the imaginary rectangle, The first highly compressed portion has a circular shape centered at an intersection point between 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 virtual rectangle and 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 virtual rectangle and is an ellipse or a rounded rectangle having a long axis along the front-rear direction, or a circle centered at the intersection of the diagonals of the virtual rectangle. The absorbent article according to claim 3.

6. 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 adjacent first highly compressed portions and second highly compressed portions is 1 to 2 mm. The absorbent article according to claim 5.

7. The virtual lattice has an oblique lattice shape in which the first virtual straight line is inclined clockwise by 40 to 50 degrees with respect to the front-rear direction in a plan view, and the second virtual straight line is inclined counterclockwise by 40 to 50 degrees with respect to the front-rear direction in a plan view. The absorbent article according to claim 3.

8. The basis weight of the pulp fiber 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 40:60 to 65:35; The non-highly compressed portion has a thickness of 3 to 13 mm, The thickness of the highly compressed portion is 60 to 90% of the thickness of the non-highly compressed portion.

3. The absorbent article according to claim 1 or 2.

9. In the total pulp fibers of the absorbent body, the proportion of pulp fibers having a fiber length of 0.5 mm or more and less than 1.1 mm is 40% or more by mass, and the proportion of pulp fibers having a fiber width of 10 μm or more and less than 35 μm is 90% or more by mass.

3. The absorbent article according to claim 1 or 2.

10. The pulp fibers of the absorbent body are made of softwood pulp fibers and hardwood pulp fibers, The mass ratio of the hardwood pulp fibers to the softwood pulp fibers is 25 / 75 or more and 38 / 62 or less.

10. The absorbent article of claim 9.

Images