Disposable diaper

Abstract

[Problem] To improve maintainability of a urine-receiving space and follow-up deformation property in a crotch part. [Solution] An absorbent body 56 has: a pair of elongated slits 56L, which extend in the longitudinal direction LD, on one side and the other side in the width direction WD in a crotch part M; a center region 56C positioned between one of the slits 56L and the other slit 56L; and a pair of side regions 56S positioned between the slits 56L on both sides in the width direction WD and the lateral edges of the absorbent body 56. In a range of at least 60% in the longitudinal direction LD of the center region 56C and the side regions 56S, grooves 53 which are recessed from at least one of the front surface and the rear surface of the absorbent body 56 to the inside of the absorbent body 56 and which have bottom parts 51 compressed in the thickness direction are provided in a continuous pattern in the width direction WD. In the center region 56C, the thickness of the bottom parts 51 of the grooves 53 is constant and the area ratio of the bottom parts 51 of the grooves 53 is lower as compared with those in the side regions 56S.

Description

Disposable diapers

[0001] The present invention relates to a disposable diaper which is designed to improve the maintenance of a urine receiving space in the crotch area (the gap between the surface of the crotch area of ​​the disposable diaper and the skin) and to improve conforming deformation.

[0002] Disposable diapers generally use an absorbent body made by mixing and accumulating pulp fibers and superabsorbent polymer particles, and in order to improve the shape retention of such absorbent bodies during and after manufacturing, they are generally built in as an absorbent element wrapped in a wrapping sheet made of crepe paper or the like (see, for example, Patent Document 1).

[0003] Since the absorbent element of a disposable diaper is sandwiched between the legs and is subjected to forces in various directions from both sides in the width direction due to leg movements such as walking, it is required to have the ability to deform in accordance with the crotch width, while also being able to maintain a desirable wearing shape. Of course, the absorbent element of a disposable diaper is also required to ensure an adequate absorption capacity in the crotch area.

[0004] For example, when worn, the crotch area of ​​a typical disposable diaper has a base at the middle of its width and side walls that rise up to form a roughly U-shaped cross section. As a result, a urine-receiving space is formed between the surface of the crotch area of ​​the disposable diaper and the skin, making it less likely to leak, even when a large amount of urine is voided at one time.

[0005] To facilitate deformation into a generally U-shaped cross-section, a pair of slits, penetrating the thickness direction, has traditionally been formed along the front-to-rear direction on both sides of the absorbent core in the width direction in the crotch area. In this case, the absorbent core is more likely to bend at the slits, with the center region between the pair of slits forming the bottom and the side regions on either side of each slit rising to form side walls. This not only facilitates the generally U-shaped cross-section of the crotch area of ​​the diaper, but also increases the rigidity of the side walls due to the presence of the absorbent core (i.e., the urine-receiving space is less likely to collapse), providing an absorbing function. However, this function is lost or significantly reduced when the absorbent core loses its shape due to the expansion of the superabsorbent polymer particles as a result of urine absorption, which reduces the absorbent core's ability to maintain its shape and causes the slits to collapse.

[0006] A known method for improving the shape retention of an absorbent body is to provide grooves with bottoms formed by compressing the absorbent element in the thickness direction in a grid-like pattern or the like (see, for example, Patent Document 1). However, since providing grooves by compression leads to improved rigidity, if compressed grooves are provided in a uniformly dense pattern throughout the absorbent body in consideration of shape retention after urine absorption, the portion located at the bottom will be less likely to bend when the crotch area is deformed into a substantially U-shaped cross section, and will be less likely to deform to follow the crotch width (deterioration of follow-up deformation ability).

[0007] Japanese Patent Application Laid-Open No. 2021-000236

[0008] Therefore, a main object of the present invention is to improve the maintenance of the urine receiving space in the crotch area and to improve the conforming and deformable properties.

[0009] The disposable diaper that solves the above problems is as follows: <First Aspect> An absorbent element has a crotch region and front and rear regions extending forward and rearward from the crotch region, an absorbent body provided over a range in the front-to-rear direction including the crotch region, and a packaging sheet that wraps the absorbent body, the absorbent body being made by mixing and accumulating pulp fibers and superabsorbent polymer particles, the absorbent body having a pair of elongated slits extending in the front-to-rear direction provided on one and the other widthwise sides of the crotch region, the absorbent body having a center region defined between one of the slits and the other of the slits, and a pair of side regions defined between the slits on both sides in the widthwise direction and the side edges of the absorbent body, the center region and the side regions having grooves that are recessed from at least one of the front and rear surfaces of the absorbent body into the absorbent body and have bottoms that are compressed in the thickness direction, in a pattern that is continuous in the widthwise direction, over 60% or more of the front-to-rear direction range, The center region has, compared to the side regions, a constant thickness of the bottoms of the grooves and a low area ratio of the bottoms of the grooves, a constant area ratio of the bottoms of the grooves and a high thickness of the bottoms of the grooves, or a low area ratio of the bottoms of the grooves and a high thickness of the bottoms of the grooves.

[0010] (Effects) This disposable diaper improves both the maintenance of the urine-receiving space in the crotch area and its ability to conform to changes in shape for the following reasons: (a) The absorbent body is easily bent at the slits, and the center region forms the bottom while the side regions rise to form side walls, which not only makes it easier for the crotch area of ​​the diaper to have a roughly U-shaped cross section, but also increases the rigidity of the side walls (i.e., makes the urine-receiving space less likely to collapse), thereby providing absorption functionality. (b) Both the center region and the side regions are provided with a predetermined pattern of grooves that extend from at least one of the front and back surfaces of the absorbent element into the absorbent body and have bottoms that are compressed in the thickness direction, so the absorbent body is more likely to maintain its shape even after absorbing urine than if this were not the case. (c) While having the advantages of (a) and (b) above, the center region is relatively flexible and the side regions are relatively shape-retaining, so that when the crotch portion of the diaper is worn in a U-shaped cross section, the side walls become more rigid and the urine receiving space is less likely to collapse, while the bottom portion is more likely to bend and deform to conform to the crotch width.

[0011] <Second Aspect> The disposable diaper of the first aspect, wherein the center region and the side regions are regions in which the grooves are continuous in a lattice pattern, the thicknesses and widths of the bottoms of the grooves in the center region and the side regions are the same, and the maximum area of ​​the unit frames formed by the grooves in the center region is 1.5 to 4 times the maximum area of ​​the unit frames formed by the grooves in the side regions.

[0012] (Effects) When grooves, each recessed from the surface of the absorbent body into the absorbent body and having a bottom compressed in the thickness direction, are provided in a continuous grid-like pattern, the high-density, highly rigid groove bottoms are continuous at least in the width direction, resulting in particularly high shape retention in the region containing the grooves, at least in the width direction. Another advantage is improved liquid diffusibility in the direction along the grooves. While shape retention varies depending on the thickness of the groove bottoms of the absorbent body, the magnitude of this change is not significant. Increasing the width of the groove bottoms also increases the feel of the hard groove bottoms on the skin. Therefore, as in this embodiment, it is preferable to make the thickness and width of the groove bottoms the same in the center region and the side region, while varying the area of ​​the unit frame consisting of the grooves. This not only improves shape retention, but also increases liquid diffusibility in the side regions compared to the center region, reducing side leakage.

[0013] <Third Aspect> The absorbent body is made of one layer or multiple layers formed by mixing and accumulating pulp fibers and highly absorbent polymer particles, and the basis weight of the pulp fibers in the absorbent body is 80 to 450 g / m ２ the absorbent body has a weight ratio of pulp fibers to superabsorbent polymer particles of 20:80 to 80:20; the maximum thickness of the absorbent body is 1 to 20 mm; the thickness of the bottom portion is 5 to 40% of the maximum thickness of the absorbent body; the width of the bottom portion is 1 to 3 mm; and the area of ​​the unit frame formed by the grooves in the center region is 150 to 500 mm ２ The disposable diaper according to the second aspect,

[0014] (Operation and Effect) The dimensions of the grooves can be determined as appropriate, but in an absorbent body such as that of this embodiment, it is preferable to form the grooves within the range of this embodiment.

[0015] <Fourth Aspect> The disposable diaper of the second or third aspect, wherein the grooves are formed in a diagonal lattice pattern, each of the grooves including first portions inclined at 40 to 60 degrees clockwise with respect to the front-to-rear direction in plan view and second portions inclined at 40 to 60 degrees counterclockwise with respect to the front-to-rear direction in plan view.

[0016] (Operation and Effect) The groove pattern can be determined as appropriate, but a diagonal lattice pattern as in this embodiment is preferable.

[0017] <Fifth Aspect> The disposable diaper according to any one of the second to fourth aspects, wherein the widthwise dimension of the unit frame in the side region is 0.5 times or less the minimum widthwise dimension of the side region.

[0018] (Effects) When configured as in this embodiment, there is at least one unit frame in the side region, which is particularly preferable in terms of both improved rigidity and improved diffusion, even if the position of the grid pattern is slightly shifted due to manufacturing errors.

[0019] <Sixth Aspect> The disposable diaper of the fifth aspect, wherein the groove pattern in both side regions consists only of slit-adjacent frames consisting of the side edges of the slits and the grooves, side edge-adjacent frames consisting of the side edges of the absorber and the grooves, and complete unit frames having the same dimensions and shape, and the area of ​​each slit-adjacent frame and each side edge-adjacent frame in both side regions is smaller than the area of ​​the unit frames.

[0020] (Operation and Effect) This configuration is preferable because when the diaper assumes a generally U-shaped cross section, the rigidity of the side walls is particularly high, making the urine receiving space less likely to collapse.

[0021] <Seventh Aspect> The disposable diaper according to any one of the first to sixth aspects, wherein both side edges of the absorber extend linearly in the front-to-rear direction, and the pair of slits extend so as to approach the side edges of the absorber from the middle in the front-to-rear direction toward the front side and the rear side, respectively.

[0022] (Effects) When the slit is shaped as in this embodiment, the center region forms the bottom and each side region rises to form a side wall, so that when the crotch area of ​​the diaper has an approximately U-shaped cross section, the side walls not only fit easily to the inside of the thighs, but also the side walls become lower in height as they go towards the front and back, making them less likely to fold, making the urine receiving space in that vicinity particularly less likely to collapse.

[0023] According to the present invention, it is possible to improve the maintenance of the urine receiving space in the crotch area and improve the conforming deformation ability.

[0024] 10 is a plan view showing the front surface of a pants-type disposable diaper in an unfolded state. FIG. 11 is a plan view showing the back surface of a pants-type disposable diaper in an unfolded state. FIG. 12 is a cross-sectional view taken along line 3-3 of FIG. 1. FIG. 13 is a cross-sectional view taken along line 4-4 of FIG. 1. FIG. 14 is a cross-sectional view taken along line 5-5 of FIG. 1. FIG. 15 is a plan view showing the front surface of the inner body. FIG. 16 is a perspective view of a pants-type disposable diaper as seen from diagonally below the front. FIG. 17 is a cross-sectional view of a main part showing a worn state. FIG. 18 is a cross-sectional view of an absorbent element. FIG. 19 is a plan view of an absorbent core. FIG. 10 is a plan view of an absorbent core. FIG. 11 is a plan view of an absorbent core in an unfolded state showing examples of slits.

[0025] The above-mentioned disposable diaper will be described in detail below with reference to an example of a pants-type disposable diaper shown in the accompanying drawings. Note that adjacent components in the thickness direction may be fixed or joined as needed, in addition to the fixed or joined portions described below, in the same manner as known diapers. The dotted patterns in the cross-sectional view indicate adhesives such as hot melt adhesives used as the fixing or joining means. Hot melt adhesives can be applied by known techniques, such as slot coating, continuous or dotted bead coating, spiral, Z-shaped, or wavy (regular or irregular) spray coating, or pattern coating (transfer of hot melt adhesive using a relief printing method). Alternatively or in addition to this, hot melt adhesive can be applied to the outer periphery of the elastic member to fix the elastic member to an adjacent member. Hot melt adhesives include, for example, EVA-based, adhesive rubber-based (elastomer-based), polyolefin-based, and polyester / polyamide-based types, but no particular limitations apply. Material welding, such as heat sealing or ultrasonic sealing, can also be used to fix or join the components. In areas where liquid permeability in the thickness direction is required, adjacent components in the thickness direction are fixed or joined in an intermittent pattern. For example, when such intermittent fixing or joining is performed using a hot melt adhesive, intermittent pattern coating such as a spiral, Z-shaped, or wavy pattern can be suitably used. When coating an area greater than the coating width of a single nozzle, intermittent pattern coating such as a spiral, Z-shaped, or wavy pattern can be performed with or without a gap in the width direction. Material welding methods such as heat sealing and ultrasonic sealing can also be used to join the components.

[0026] In addition, as the nonwoven fabric in the following description, known nonwoven fabrics can be used appropriately depending on the location and purpose. The constituent fibers of the nonwoven fabric can be selected without particular limitation, for example, synthetic fibers such as polyolefins (e.g., polyethylene or polypropylene), polyesters, and polyamides (including single-component fibers and core-sheath and other composite fibers), regenerated fibers (e.g., rayon or cupra), and natural fibers (e.g., cotton), and mixtures of these can also be used. In order to increase the flexibility of the nonwoven fabric, it is preferable that the constituent fibers be crimped fibers. Furthermore, the constituent fibers of the nonwoven fabric can be hydrophilic fibers (including fibers made hydrophilic by a hydrophilizing agent), hydrophobic fibers, or water-repellent fibers (including fibers made water-repellent by a water-repellent agent). Furthermore, nonwoven fabrics are generally classified into staple fiber nonwoven fabrics, long fiber nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, thermal bond (air-through) nonwoven fabrics, needle-punched nonwoven fabrics, point-bond nonwoven fabrics, laminated nonwoven fabrics (including SMS nonwoven fabrics and SMMS nonwoven fabrics in which a meltblown layer is sandwiched between spunbond layers), and the like, depending on the fiber length, sheet formation method, fiber bonding method, and laminated structure, and any of these nonwoven fabrics can be used.

[0027] 1 to 7 show an example of a pants-type disposable diaper. The pants-type disposable diaper 100 includes a rectangular front outer body 12F that defines a front waist region FT, a rectangular rear outer body 12B that defines a rear waist region BT, and an inner body 200 that is joined to the middle of the outer bodies 12F, 12B in the width direction WD and extends from the front outer body 12F through the crotch region M to the rear outer body 12B. Side seals 12A are formed by joining both sides of the front outer body 12F to both sides of the rear outer body 12B, and thereby an opening formed by the front and rear edges of the outer bodies 12F, 12B serves as a waist opening WO through which the wearer's torso passes, and portions on both sides of the inner body 200 in the width direction WD that are surrounded by the lower edges of the outer bodies 12F, 12B and the side edges of the inner body 200 serve as leg openings LO through which the legs pass. The inner body 200 is a portion that absorbs and retains excrement such as urine, and the outer bodies 12F, 12B are portions that support the inner body 200 against the wearer's body. Furthermore, the symbol Y indicates the overall length of the diaper in the unfolded state (the length in the front-to-back direction from the edge of the waist opening WO of the front body F to the edge of the waist opening WO of the back body B), and the symbol X indicates the overall width of the diaper in the unfolded state.

[0028] The pants-type disposable diaper 100 has a waist region T defined as the front-to-back range having the side seals 12A (the front-to-back range from the waist opening WO to the upper ends of the leg openings LO), and an intermediate region L defined as the front-to-back range of the portion forming the leg openings LO (between the front-to-back region having the side seals 12A of the front body F and the front-to-back region having the side seals 12A of the back body B). The portions of the front exterior body 12F and the rear exterior body 12B located in the waist region T, i.e., the front waist region FT and the rear waist region BT, can be conceptually divided into a "waist region" W that forms the edge of the waist opening, and a "lower waist region" U that is the portion below this. Typically, if the front waist-surrounding portion FT and the rear waist-surrounding portion BT have a boundary where the stretch stress in the width direction WD changes (e.g., where the thickness or elongation rate of the elastic member changes), the waist portion W is the portion closer to the waist opening WO than the boundary closest to the waist opening WO. If no such boundary exists, the waist portion W is the portion extending further toward the waist opening WO than the absorbent body 56 or the inner body 200. Their front-to-rear lengths vary depending on the size of the product and can be determined as appropriate. For example, the waist portion W may be 15 to 40 mm, and the lower waist portion U may be 65 to 120 mm. Meanwhile, both side edges of the middle region L are constricted in a U-shape or curved shape to fit around the wearer's legs, and these are the areas into which the wearer's legs are inserted. As a result, the pants-type disposable diaper in its unfolded state has a generally hourglass shape overall.

[0029] (Fixing Region of Inner Body) The inner body 200 can be fixed to the outer bodies 12F, 12B by a joining method that uses material welding, such as heat sealing or ultrasonic sealing, or by a hot melt adhesive HM3. In the illustrated example, the back surface of the inner body 200 is fixed to the inner surface of the outer bodies 12F, 12B via the hot melt adhesive HM3. In the illustrated example, this fixing region 201 of the inner body 200 is provided in the region where the front waistline portion FT and the rear waistline portion BT overlap with the inner body 200. It is preferable that the fixing region of the inner body be provided over substantially the entire area except for the periphery of the region where the outer bodies 12F, 12B and the inner body 200 overlap.

[0030] (Outer Body) As shown in the illustrated example, the outer bodies 12F, 12B are composed of a rectangular front outer body 12F, which constitutes at least the front waistband FT (the waistband of the front body F), and a rectangular back outer body 12B, which constitutes at least the back waistband BT (the waistband of the back body B). The front outer body 12F and the rear outer body 12B may not be continuous at the crotch side but may be spaced apart in the front-to-back direction LD (two-piece outer body type). Alternatively, although not shown, they may be continuous from the front body F through the crotch region M to the back body B (front and rear integrated outer body type). In the two-piece outer body type, the front-to-back separation distance 12d can be, for example, approximately 40 to 60% of the total length Y. In the illustrated example, the lower edges of the front outer body 12F and the rear outer body 12B are linear and extend along the width direction WD. However, the lower edge of at least one of the front outer body 12F and the rear outer body 12B may be curved to fit around the legs.

[0031] In a pants-type disposable diaper with a two-piece exterior, the interior body 200 is exposed between the front exterior body 12F and the rear exterior body 12B, and therefore, to prevent the liquid-impermeable sheet 11 from being exposed on the back surface of the interior body 200, it is preferable to provide a cover nonwoven fabric layer 13 on the back surface of the interior body 200, extending 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 layer 13 can be bonded to their opposing surfaces via a second hot melt adhesive HM2 and a third hot melt adhesive HM3. The nonwoven fabric used for the cover nonwoven fabric layer 13 can be selected appropriately from, for example, the same material as that of the exterior bodies 12F, 12B.

[0032] In the example shown in Figures 1 and 2, the front-to-back dimension of the rear outer body 12B is longer than that of the front outer body 12F, the front outer body 12F does not have a portion corresponding to the middle region L, and the rear outer body 12B has a buttocks cover portion 14 extending from the waist region T toward the middle region L, but the front-to-back dimension LD of the front outer body 12F and the rear outer body 12B may be equal, and the front outer body 12F and the rear outer body 12B may not have a portion corresponding to the middle region L.

[0033] 3 to 5, the exterior bodies 12F, 12B are formed by joining an outer sheet layer 12S and an inner sheet layer 12H adjacent to the outer and inner sides of the elastic members 15 to 17, respectively, by a joining means such as a hot melt adhesive or welding. As shown in Fig. 5, the outer sheet layer 12S and the inner sheet layer 12H are formed by folding a single sheet material so that the fold is located on the waist opening side, or, although not shown, they can also be formed by bonding two sheets of sheet material together.

[0034] The sheet material used for the outer sheet layer 12S and the inner sheet layer 12H is not particularly limited, but nonwoven fabric is preferred. When nonwoven fabric is used, the basis weight per sheet is 8 to 20 g / m ２ It is preferable to set it to about this level.

[0035] To improve the fit around the wearer's waist, the outer shells 12F, 12B have elastic members 15-17 attached between the outer sheet layer 12S and the inner sheet layer 12H at a predetermined elongation rate, forming an elastic region that elastically stretches in the width direction WD together with the elastic members 15-17. The elastic region can contract along with the elastic members 15-17 and stretch between a natural length state in which wrinkles or creases are formed and an elongated state in which the elastic members 15-17 are fully elongated in the width direction to a predetermined elongation rate without wrinkles. The elastic members 15-17 may be elongated elastic members such as rubber thread (illustrated example), or known elastic members such as strips, nets, and films, without any particular limitation. The elastic members 15-17 may be made of synthetic or natural rubber. The outer sheet layer 12S and the inner sheet layer 12H of the exterior bodies 12F, 12B can be bonded together, and the elongated elastic members 15-17 sandwiched therebetween can be secured using at least one of various application methods of hot melt adhesive and material welding, such as heat sealing or ultrasonic sealing. Since strongly securing the entire surface of the exterior bodies 12F, 12B reduces flexibility, it is preferable to either not secure or only weakly secure the elongated elastic members 15-17 in areas other than the adhesive bonded portions. In the illustrated example, hot melt adhesive is applied only to the outer peripheral surfaces of the elongated elastic members 15-17 using an application means such as a comb gun or a SureWrap nozzle, and then the elongated elastic members are sandwiched between the sheet layers 12S, 12H. This structure allows the elongated elastic members 15-17 to be secured to the sheet layers 12S, 12H and the sheet layers 12S, 12H together using only the hot melt adhesive applied to the outer peripheral surfaces of the elongated elastic members 15-17.

[0036] To explain the elastic members 15-17 in the illustrated example in more detail, a plurality of waist elastic members 17 are attached between the outer sheet layer 12S and the inner sheet layer 12H in the waist region W of the outer bodies 12F, 12B at intervals in the front-to-rear direction and stretched in the width direction at a predetermined stretch rate, forming a continuous waist stretch region across the entire width direction WD. Furthermore, one or more of the waist elastic members 17 arranged in the region adjacent to the lower waist region U may overlap the inner body 200, or may be provided on both sides of the width direction WD except for the central portion in the width direction that overlaps with the inner body 200. The waist elastic members 17 should have a thickness of 300 to 940 dtex, particularly 470 to 780 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 1 / 4" thick (approximately 1 / 4" thick) at intervals of 2 to 12 mm, especially 3 to 7 mm, and the resulting elongation rate in the width direction WD of the waist portion W is preferably about 150 to 300%, especially about 200 to 280%. Furthermore, it is not necessary for the waist portion W to use elastic members of the same thickness or to have the same elongation rate all along the front-to-back direction LD, and for example, the thickness or elongation rate may be different in some areas.

[0037] In addition, between the outer sheet layer 12S and the inner sheet layer 12H in the lower waist portion U of the outer bodies 12F, 12B, a plurality of lower waist elastic members 15 made of elongated elastic members are attached at intervals in the front-to-rear direction and in a state stretched in the width direction at a predetermined stretch rate, forming lower waist stretchable regions on both sides in the width direction WD except for the central part in the width direction that overlaps with the inner body 200. The lower waist elastic members 15 have a thickness of 300 to 940 dtex, particularly about 470 to 780 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 ２It is preferable to provide about 5 to 30 rubber threads of about 1 / 2" thick (approximately 1 / 4" thick) at intervals of 1 to 15 mm, especially 3 to 8 mm, and the resulting elongation rate in the width direction WD of the waist lower portion U is preferably about 200 to 350%, especially about 240 to 300%. Furthermore, it is not necessary for the waist lower portion U to use elastic members of the same thickness or to have the same elongation rate all along the front-to-back direction LD, and thicknesses or elongation rates may be different in some areas.

[0038] In addition, between the outer sheet layer 12S and the inner sheet layer 12H in the buttocks cover portion 14 of the rear exterior body 12B, one or more buttocks cover elastic members 16 made of elongated elastic members are attached at intervals in the vertical direction and stretched in the width direction at a predetermined stretch rate on both sides in the width direction WD except for the width center portion overlapping with the interior body 200, forming buttocks cover stretchable regions on both sides in the width direction WD except for the width center portion overlapping with the interior body 200. The buttocks cover elastic members 16 have a thickness of 300 to 940 dtex, particularly about 470 to 780 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 fix about 2 to 10 rubber threads (approximately 150 to 300%, particularly 180 to 260%) at intervals of 5 to 40 mm, particularly 5 to 20 mm, each having an elongation of 150 to 300%, particularly 180 to 260%.

[0039] Of the front waistband FT and the rear waistband BT, the first region consisting of the portion overlapping with the absorbent 56 and the portion between this and the side seal 12A is an intermittent stretch band A1 having a non-stretch region 12X provided in at least the middle portion in the width direction WD of the portion overlapping with the absorbent 56, and a stretch region provided between the non-stretch region 12X and each of the side seals 12A, and it is preferable that the second region located between this intermittent stretch band A1 and the waist opening WO is a continuous stretch band A2 in which the stretch region continues in the width direction WD from one side seal 12A to the other side seal 12A.

[0040] In the illustrated example, the intermittent stretchable band A1 may extend beyond the first region (beyond the absorbent body 56) to the waist opening WO side, as long as it includes the first region. In the illustrated example, in the rear waistband BT, only the first region is the intermittent stretchable band A1, and the region between the first region and the waist opening WO is the continuous stretchable band A2, and in the front waistband FT, the region consisting of the portion overlapping with the fixed region 201 of the inner body 200 and the portion between this and the side seal 12A (the region extending beyond the first region to the waist opening WO side) is the intermittent stretchable band A1, but this is not limited to this. Therefore, these may be reversed, or the region consisting of the portion overlapping with the fixed region 201 of the inner body 200 and the portion between this and the side seal 12A in both the front waistband FT and the rear waistband BT may be the intermittent stretchable band A1, or only the first region in both the front waistband FT and the rear waistband BT may be the intermittent stretchable band A1. In addition, the intermittent stretch band A1 in the illustrated example is formed in a range in the front-to-back direction LD that includes only the lower waist stretch area having the lower waist elastic member 15, but the range may be expanded toward the waist opening WO to include a portion of the waist stretch area having the lower waist elastic member 17.

[0041] In the illustrated example, the continuous stretchable band A2 is formed only by a waist stretchable region having waist elastic members 17 in the front waist portion FT, and is formed by the entire waist stretchable region having waist elastic members 17 and a portion of the lower waist stretchable region including the lower waist elastic members 15 in the back waist portion BT, but is not limited to this. Therefore, these may be reversed, or the continuous stretchable bands A2 in both the front waist portion FT and the back waist portion BT may be formed only by a waist stretchable region having waist elastic members 17, or may be formed by the entire waist stretchable region having waist elastic members 17 and a portion of the lower waist stretchable region having the lower waist elastic members 15.

[0042] As shown in the figure, if the first region consisting of the portion overlapping with the absorbent body 56 and the portion between this and the side seal 12A is an intermittent stretch band A1 rather than a continuous stretch band A2, the absorbent body 56 will not shrink more than necessary in the width direction WD, and there will be no deterioration in fit, a poor appearance due to bulkiness, or a decrease in absorbency. Such intermittent stretch bands A1 may have elastic members 15, 16 only on both sides in the width direction WD, or may have elastic members 15, 16 present across the absorbent body 56 from one side to the other in the width direction WD, but the widthwise intermediate portion or all of the portion overlapping with the absorbent body 56 may be cut into small pieces so that almost no contractile force acts on it (effectively equivalent to no elastic members 15, 16 being present), forming a non-stretchable region 12X, and both sides in the width direction WD may be stretchable regions (portions where contractile force acts). The non-stretchable region 12X is preferably located between both side edges of the inner body 200, and more preferably between both side edges of the absorbent body 56. The dimension in the width direction WD of the non-stretchable region 12X can be determined as appropriate, but is preferably 0.6 to 1.2 times, and more preferably 0.8 to 1.0 times, the maximum width of the absorbent body 56. The dimension in the width direction WD of the non-stretchable region 12X is also preferably 0.5 to 1.0 times, and more preferably 0.6 to 0.8 times, the dimension in the width direction WD of the continuous stretchable band A2.

[0043] (Inner body) The inner body 200 may have any shape, but is rectangular in the illustrated example. As shown in Figures 3 to 5, the inner body 200 comprises a liquid-permeable top sheet 30 that faces the wearer's skin, a liquid-impermeable sheet 11, and an absorbent element 50 sandwiched between them. Reference numeral 60 denotes side flaps 60 having flat gathers.

[0044] (Top Sheet) The top sheet 30 can be made of any liquid-permeable material, such as a perforated or non-perforated nonwoven fabric or a perforated plastic sheet, without any particular limitations. However, when the top sheet 30 also serves as a covering material for the liquid-impermeable sheet layer 64, as in the examples shown in Figures 3 and 4, the top sheet 30 is preferably made of a nonwoven fabric.

[0045] The side edges of the top sheet 30 may be folded back to the back of the absorbent element 50 at the side edges of the absorbent element 50, or may not be folded back and may extend out to the sides beyond the side edges of the absorbent element 50. If necessary, the overall width of the top sheet 30 may be made shorter than the overall width of the absorbent element 50, so that both side edges of the top sheet 30 are positioned above the absorbent element 50.

[0046] (Intermediate Sheet) Although not shown, an intermediate sheet (also called a "second sheet") that has a faster liquid permeability rate than the top sheet 30 can be provided in order to quickly transfer liquid that has permeated the top sheet 30 to the absorbent body. This intermediate sheet is intended to quickly transfer liquid to the absorbent body, improving the absorption performance of the absorbent body and preventing the phenomenon of absorbed liquid "flowing back" from the absorbent body. The intermediate sheet can also be omitted.

[0047] (Liquid-impermeable sheet) The material of the liquid-impermeable sheet 11 provided on the back side of the absorbent body 56 is not particularly limited, but examples include plastic films made of polyolefin resins such as polyethylene and polypropylene. In recent years, it is preferable to use a liquid-impermeable and moisture-permeable material, which has been used with preference 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 to form a sheet and then stretching it in a uniaxial or biaxial direction is widely used.

[0048] The liquid-impermeable sheet 11 can be configured to extend into the side flaps to improve the waterproofness of the flat gathers, as in the examples shown in Figures 3 and 4, or it can be made wide enough to fit on the back side of the absorbent element 50 (not shown), or it can be folded back to the front side at the side edges of the absorbent element 50 and extend between the absorbent element 50 and the top sheet 30.

[0049] 3, 4 and 9, the absorbent element 50 has an absorbent body 56 and a wrapping sheet 58 that wraps the entire absorbent body 56. The wrapping sheet 58 may be omitted.

[0050] (Absorbent body) The absorbent body 56 is a mixture of pulp fibers and highly absorbent polymer particles. The basis weight of the pulp fibers is, for example, 80 to 450 g / m ２ More preferably, 80 to 200 g / m ２ It can be about.

[0051] Superabsorbent polymer particles are mixed into the fiber aggregate. Superabsorbent polymer particles include not only "particles" but also "powder." The superabsorbent polymer particles used in this type of disposable diaper can be used as is. For example, when sieved using a 500 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), the percentage of particles remaining on the sieve is preferably 30% by weight or less. Furthermore, when sieved using a 180 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), the percentage of particles remaining on the sieve is preferably 60% by weight or more.

[0052] The material for the superabsorbent polymer particles is not particularly limited, but is preferably one with a water absorption capacity of 40 g / g or more (JIS K7223-1996 "Test method for water absorption capacity of superabsorbent polymers") . Examples of superabsorbent polymer particles include starch-based, cellulose-based, and synthetic polymer-based ones, and examples that can be used include starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, crosslinked products of sodium carboxymethylcellulose, and acrylic acid (salt) polymers. The shape of the superabsorbent polymer particles is preferably a commonly used powder-like shape, but other shapes can also be used.

[0053] The highly absorbent polymer particles preferably have a water absorption rate of 70 seconds or less, particularly 40 seconds or less. If the water absorption rate is too slow, the liquid supplied into the absorbent body 56 tends to flow back out of the absorbent body 56, which is known as backflow.

[0054] Furthermore, the highly absorbent polymer particles preferably have a gel strength of at least 1000 Pa. This effectively prevents the sticky feeling after absorbing liquid, even when the absorbent body 56 is bulky.

[0055] The basis weight of the highly absorbent polymer particles can be determined appropriately depending on the absorption amount required for the application of the absorbent body 56. Therefore, although it cannot be generally stated, it is generally in the range of 50 to 350 g / m ２ The polymer weight can be 50 g / m ２ If it is less than 350 g / m, it will be difficult to ensure sufficient absorption. ２ Above this, the effect saturates.

[0056] The ratio of fibers to superabsorbent polymer particles in the absorbent body 56 is not particularly limited, and for example, the weight ratio of pulp fibers to superabsorbent polymer particles can be 20:80 to 80:20, more preferably 40:60 to 60:40. In particular, a weight ratio of pulp fibers to superabsorbent polymer particles of 40:60 to 60:40 can result in a thinner absorbent body 56 when compared for the same area and the same absorption capacity. The thickness 56t of the absorbent body 56 is not particularly limited, but can be 1 to 20 mm, more preferably 2 to 5 mm.

[0057] The absorbent body 56 is provided over a range in the front-to-rear direction LD, including the crotch region M. The absorbent body 56 preferably extends from the front waist region FT to the rear waist region BT. The portion of the absorbent body 56 located in the fixing region 201 of the inner body 200 is preferably fixed to the outer bodies 12F, 12B via a packaging sheet 58, a liquid-impermeable sheet 11, a hot-melt adhesive HM3, or the like. The symbol 56X indicates the maximum width (total width) of the absorbent body 56.

[0058] It is preferable that the absorbent body 56 has a generally rectangular shape as shown in the example, as this makes it easier to ensure the amount of absorption in the crotch region M, but it may also have a constricted portion in the crotch region M (i.e., the absorbent body 56 has a minimum width portion located midway in the front-to-rear direction LD, and widening portions that gradually increase in width from this minimum width portion to a maximum width portion forward of the crotch region M, and to a maximum width portion rearward of the crotch region M).

[0059] The crotch area M refers to a range in the front-to-rear direction LD having a slit, which will be described later, and the front and rear portions extend forward and rearward from this range, respectively.

[0060] (Slits) The absorbent body 56 has a pair of elongated slits 56L extending in the front-to-rear direction LD on one side and the other side of the crotch region M in the width direction WD. Providing such slits 56L in the absorbent body 56 encourages bending of the absorbent body 56 along the slits 56L during wear, thereby deforming the crotch region M of the diaper into a generally U-shaped cross-section, as shown in Fig. 8 . That is, a center region 56C defined between one slit 56L and the other slit 56L forms the bottom, and a pair of side regions 56S defined between the slits 56L on both sides in the width direction WD and the side edges 56e of the absorbent body 56 rise up to form side walls, thereby forming a generally U-shaped cross-section of the diaper. The center region 56C and the pair of side regions 56S are indicated by dotted patterns in Fig. 14 .

[0061] As long as the slit 56L is elongated in the front-to-rear direction LD, it may extend linearly along the front-to-rear direction LD as shown in FIG. 14( b), or may extend closer to the side edges of the absorber 56 as it extends from the middle of the slit 56L in the front-to-rear direction LD toward the front and rear, respectively, as shown in FIG. 14( a) and other figures. At least one of the front and rear ends of the slit 56L may be spaced apart from the side edges of the absorber 56 as shown in FIGS. 14( a) and 14( b), or one or both of the front and rear ends may reach the side edges of the absorber 56 as shown in FIGS. 14( c) and 14( d). The front and rear ends of the slit 56L may have any suitable shape. For example, they may be linear as shown in the example shown in FIG. 14( d), or may have a curved, bulging shape (such as a semicircular arc) as shown in the example shown in FIG. 14( a), or may have rounded corners at both ends and a linear middle portion (not shown). The width m1 of the slit 56L can be determined as appropriate, for example, to be 4 to 12 mm. The width m1 of the slit 56L may be constant or may vary along its length. The dimension and arrangement of the slit 56L in the front-to-rear direction LD can be determined as appropriate. For example, the dimension m2 of the slit 56L in the front-to-rear direction LD (equal to the dimension of the crotch region M in the front-to-rear direction LD) can be 200 to 600%, more preferably 300 to 500%, of the minimum spacing CW between the slits 56L.

[0062] (Packaging Sheet) When the packaging sheet 58 is used, its material can be a liquid-permeable material such as tissue paper, particularly crepe paper, nonwoven fabric, polylaminated nonwoven fabric, or a perforated sheet. However, it is desirable that the sheet be one that does not allow the superabsorbent polymer particles to escape. When using nonwoven fabric instead of crepe paper, a hydrophilic nonwoven fabric having a dense layer is preferred. As such a nonwoven fabric, a laminated nonwoven fabric (including an SMS nonwoven fabric, an SSMMS nonwoven fabric, etc.) in which one or more meltblown layers are laminated with one or more protective layers such as a non-spunbonded layer that protects the meltblown layer is particularly preferred, and the material can be polypropylene, a polyethylene / polypropylene composite, or the like. The basis weight of the packaging sheet 58 can be, for example, 5 to 40 g / m ２ , preferably 8 to 20 g / m ２ It can be said that:

[0063] The packaging structure of the packaging sheet 58 can be determined as appropriate, but from the standpoint of ease of manufacturing and prevention of leakage of superabsorbent polymer particles from the front and rear edges, it is preferable that the packaging sheet 58 be wrapped in a cylindrical shape so as to surround the front, back, and both side surfaces of the absorbent body 56. The packaging sheet 58 may extend beyond the front and rear edges of the absorbent body, or, as in the illustrated example, the front and rear edges of the packaging sheet 58 may be approximately aligned with the front and rear edges of the absorbent body.

[0064] (Side Flaps) As shown in Figures 1 to 4, 7, and 8, the inner body 200 preferably has side flaps 60. The side flaps 60 are a pair of portions extending from the side edges of the absorbent body 56 on both sides in the width direction WD, and each extend in the front-to-back direction LD from a region overlapping with the waist-around stretchable region of the front body F (in the illustrated example, the region having the waist-down elastic member 15) to a region overlapping with the waist-around stretchable region of the back body B (in the illustrated example, the region having the waist-down elastic member 15). The side flaps 60 also have side nonwoven fabrics 66 extending from the front surface of the side flaps 60, over the side edges of the side flaps 60, to the back surface of the side flaps 60, and elongated gathered elastic members 631-633 provided along the front-to-back direction LD between the front surface portion 61 and the back surface portion 62 of the side flaps 66. The front surface portion 61 and the back surface portion 62 extend across the entire side flap 60 in the front-to-back direction LD. In the illustrated example, the surface portion 61 is formed by the folded-back portion 66r of the side nonwoven fabric 66, but is not limited to this. The front and rear ends of the side flaps 60 do not contract in the front-to-back direction LD together with the gathered elastic members 631-633, and form side non-stretchable regions 70 having fixed portions 67 where the surface portion 61 is fixed to the back portion 62. The portions of the side flaps 60 between the front and rear non-stretchable side regions 70 form flat gathered regions 80 to which the gathered elastic members 631-633 are fixed, contract in the front-to-back direction LD together with the gathered elastic members 631-633, and are stretchable in the front-to-back direction LD together with the gathered elastic members 631-633. This pants-type disposable diaper does not have three-dimensional gathers that rise up on the front side, but only has flat gathers on the side flaps 60. In the fixing portion 67 shown in the figure, the surface portion 61 is indirectly fixed to the back portion 62 via the liquid-impermeable sheet layer 64, but if no other member such as the liquid-impermeable sheet layer 64 is interposed, the surface portion 61 will be fixed directly.

[0065] The dimension of the side non-elasticated regions 70 in the front-to-rear direction LD may be different or the same at the front and rear ends of the side flaps 60, as shown in the example. Note that the reference symbol 60w in the figure indicates the dimension in the width direction WD of the side flaps 60. Furthermore, the reference symbol w1 indicates the distance in the width direction WD between the fastening portion 67 and the side edge of the side non-elasticated region 70 (first distance), the reference symbol w2 indicates the dimension in the width direction WD of the portion of each side edge (side flap) of the inner body that is not fastened to the outer body 12 (second distance), the reference symbol w3 indicates the dimension in the width direction WD of the fastening portion 67, the reference symbol w4 indicates the distance in the width direction WD between the fastening portion 67 and the side edge of the absorbent body 56 (third distance), and the reference symbol w5 indicates the distance in the width direction WD between the fastening portion 67 and the edge of the surface portion 61 on the center side in the width direction WD (fourth distance).

[0066] The gathered elastic members 631-633 can be elongated elastic members such as rubber threads or rubber strips. When rubber threads are used, the thickness of the gathered elastic members 631-633 is preferably 400-950 dtex, and more preferably 470-780 dtex. The elongation percentage of the gathered elastic members 631-633 is preferably 200-320%, and more preferably 240-320%. In the figure, reference numeral 631 indicates a first gathered elastic member located first counting from the absorbent body 56 side, reference numeral 632 indicates a second gathered elastic member located second, and reference numeral 633 indicates a third gathered elastic member located third or later. Furthermore, symbol d1 indicates the distance in the width direction WD (first distance) between the side edge of the widest part of the absorbent body 56 and the first gathered elastic member 631, symbol d2 indicates the distance in the width direction WD between the first gathered elastic member 631 and the second gathered elastic member 632 (second distance), and symbol d3 indicates the distance in the width direction WD between the second gathered elastic member 632 and the third gathered elastic member 633 and the distance in the width direction WD between adjacent third gathered elastic members 633 (third distance).

[0067] To bond adjacent layers in the thickness direction of the side flap 60 together and to secure the gathered elastic members 631-633 sandwiched therebetween, at least one of various application methods of hot melt adhesive and material welding, such as heat sealing and ultrasonic sealing, can be used. Bonding the entire surfaces of the layers adjacent to the front and back sides of the gathered elastic members 631-633 together impairs flexibility, so it is preferable to not bond or only weakly bond the areas other than the adhesive joints of the gathered elastic members 631-633. In the illustrated example, hot melt adhesive is applied only to the outer peripheral surfaces of the gathered elastic members 631-633 using an application means such as a comb gun or a SureWrap nozzle, and the gathered elastic members 631-633 are sandwiched between the adjacent layers on the front and back sides. This structure allows the hot melt adhesive applied only to the outer peripheral surfaces of the gathered elastic members 631-633 to bond the gathered elastic members 631-633 to the layers adjacent to them on the front and back sides, and to bond the layers adjacent to the front and back sides of the gathered elastic members 631-633 to each other using only the hot melt adhesive applied to the outer peripheral surfaces of the gathered elastic members 631-633. If there is an end of a nonwoven fabric or sheet that is separated from the gathered elastic members 631-633, such as the end of the top sheet 30 in the illustrated example, a separate hot melt adhesive (first hot melt adhesive HM1 in the illustrated example) can be applied to secure it.

[0068] The side nonwoven fabric 66 may be a nonwoven fabric that is soft and has excellent uniformity and hiding power, such as a spunbond nonwoven fabric (SS, SSS, etc.), an SMS nonwoven fabric (SMS, SSMMS, etc.), or a meltblown nonwoven fabric, and is treated with a water repellent agent such as silicone as necessary. The fiber weight is 10 to 30 g / m. ２ 3 and 4, as can be seen from the fact that the surface nonwoven fabric layer on the proximal side of the nonwoven fabric-free portion 65 is formed by the top sheet 30, it is also possible to make the materials of the surface nonwoven fabric layer and the back nonwoven fabric layer partially different, and it is also possible to make the materials of the surface nonwoven fabric layer and the back nonwoven fabric layer different.

[0069] (Grooves) As shown in Figures 9 to 11, the absorbent body 56 preferably has grooves 53 recessed from the surface of the absorbent body 56 into the absorbent body 56 and having bottoms 51 compressed in the thickness direction. The bottoms 51 of the grooves 53 are high-density portions compressed by pressure (direct pressure) to a substantially uniform thickness. Hereinafter, the portions other than the bottoms 51 are referred to as non-compressed portions 52. The non-compressed portions 52 are thicker and lower-density than the bottoms 51. However, even in the non-compressed portions 52, the absorbent body 56 deforms near the periphery of the bottoms 51 as if pulled by the compression of the bottoms 51, resulting in an increase in density as it approaches the bottoms 51. As long as the non-compressed portions 52 are thicker and lower-density than the bottoms 51, they may be entirely compressed in the thickness direction simultaneously with, before, or after the compression process that forms the bottoms 51. The shape and arrangement of the non-compressed portions 52 are determined according to the shape and arrangement of the bottoms 51.

[0070] The grooves 53 of the absorbent body 56 may be formed by subjecting only the absorbent body 56 to embossing with or without heating, or may be formed by embossing the absorbent body 56 and other laminated members, such as the absorbent element 50 (i.e., together with the packaging sheet 58) and the inner body 200, in a laminated state.

[0071] If the above-described grooves 53 are provided in a continuous pattern in the width direction WD over a range of 60% or more in the front-to-rear direction LD in the center region 56C and the side regions 56S, the compressed bottom portions 51 will have high density and high rigidity, improving the shape retention of the center region 56C and the side regions 56S. However, since providing compressed bottom portions 51 leads to improved rigidity, providing compressed bottom portions 51 in a uniformly dense pattern throughout the center region 56C and the side regions 56S in consideration of shape retention after urine absorption will make the portion located at the bottom (the center region 56C) less likely to bend and less likely to deform to conform to the crotch width when the crotch region M deforms into a generally U-shaped cross-section (reducing conforming deformability). Therefore, it is preferable that the thickness of the bottom portions 51 of the grooves 53 be constant and the area ratio of the bottom portions 51 of the grooves 53 be lower in the center region 56C than in the side regions 56S. Alternatively, although not shown, the center region 56C may have a constant area ratio of the bottoms 51 of the grooves 53 and a thicker bottom 51 of the grooves 53 compared to the side regions 56S, or the area ratio of the bottoms 51 of the grooves 53 may be reduced and the thickness of the bottoms 51 of the grooves 53 may be increased. By varying at least one of the area ratio and the thickness of the bottoms 51 of the grooves 53 to make the rigidity of the center region 56C in the crotch region M lower than that of the side regions 56S, the maintenance and conforming deformation of the urine receiving space SP in the crotch region are improved as shown in Figure 8 for the following reasons: (a) The absorbent body 56 is more easily bent at the slits 56L, and the center region 56C forms the bottom and the side regions 56S rise to form side walls. This not only facilitates the formation of a generally U-shaped cross section in the diaper, but also increases the rigidity of the side walls (i.e., makes the urine receiving space SP less likely to collapse), thereby providing an absorbing function. (i) Both the center region 56C and the side region 56S have grooves 53 in a predetermined pattern that extend from at least one of the front and back surfaces of the absorbent element 50 into the absorbent body 56 and have bottoms 51 that are compressed in the thickness direction. Therefore, compared to cases where this is not the case, the absorbent body 56 is more likely to maintain its shape even after absorbing urine.(c) While having the advantages of (a) and (b) above, the center region 56C is relatively flexible and the side regions 56S are relatively shape-retaining, so that when the crotch region M of the diaper is worn in a U-shaped cross section, the side walls become more rigid and the urine receiving space SP is less likely to collapse, while the bottom portion is more likely to bend and deform to conform to the crotch width.

[0072] As long as the grooves 53 are provided in a pattern that is continuous in the width direction WD over a range of 60% or more of the center region 56C and the side regions 56S in the front-to-rear direction LD, they may be formed over a range of 80% or more in the front-to-rear direction LD, or they may be formed over the entire front-to-rear direction LD as in the illustrated example, or they may be formed only in a range of 60% or more but less than 100% in the front-to-rear direction LD from the front or rear end of the center region 56C and the side regions 56S, or they may be formed only in the intermediate portions between the front and rear ends of the center region 56C and the side regions 56S, without being formed at the front and rear ends. In particular, it is preferable that the pattern of the grooves 53 is uniformly continuous over the entire range in the front-to-rear direction LD from forward of the front ends of the center region 56C and the side regions 56S to rear of the rear ends of the center region 56C and the side regions 56S (in the illustrated example, the entire front-to-rear direction LD of the absorbent body 56), because this eliminates the need for positioning the grooves 53 in the front-to-rear direction LD and facilitates manufacturing. However, the area including 60% or more of the center area 56C and the side areas 56S in the front-rear direction LD and the other areas may have grooves 53 with different patterns.

[0073] The dimensions and number of the bottoms 51 of the grooves 53 can be determined as appropriate, but it is preferable that the depth 51h of the bottoms 51 (thickness 56t of the absorbent body 56 - thickness 51t of the groove bottoms) is 0.5 to 5 mm, and the area ratio of the bottoms 51 of the grooves 53 (the ratio of the area of ​​the bottoms 51 to the surface of the absorbent element 50) is 20 to 40%.

[0074] As long as the grooves 53 having bottom portions 51 are continuous in the width direction WD, they may be arranged in a continuous grid-like pattern as shown in Figures 10 and 11 , or, although not shown, in a horizontal stripe pattern where multiple grooves 53 extending along the width direction WD are spaced apart in the front-to-back direction LD, a diagonal stripe pattern where multiple grooves 53 extending along a diagonal direction are spaced apart in a direction perpendicular to the continuous direction of the grooves 53 (a diagonal stripe pattern), multiple wavy grooves 53 are spaced apart in the front-to-back direction LD, or in other geometric patterns, or in a continuous pattern featuring motifs such as letters, animals, or plants. Therefore, the non-compressed portions 52 are arranged intermittently at least in the front-to-back direction LD. In particular, when the grooves 53 are arranged in a continuous grid-like pattern, the pulp fibers and superabsorbent polymer particles constituting the absorbent body 56 are confined within the unit frame 54 (minimum frame) consisting of the bottom portions 51 compressed in the thickness direction, which contributes to reducing twisting and cracking of the absorbent body 56.

[0075] The width 51w of the bottom 51 of the groove 53 can be determined as appropriate, but in normal cases it is preferably about 1 to 3 mm.

[0076] The thickness 51t of the bottom 51 of the groove 53 can be determined as appropriate, but in general, it is preferably 5 to 40%, particularly 5 to 30%, of the maximum thickness 50t of the absorbent element 50.

[0077] When the grooves 53 are arranged in a lattice pattern, the shape of the unit frames 54 is not particularly limited, and may be a substantially square shape as in the illustrated example, a substantially rhombic shape (excluding a square), a substantially rectangular shape, a substantially square shape, a substantially triangular shape, or any other polygonal shape. Furthermore, as long as the bottoms 51 of the grooves are arranged in a lattice pattern, the unit frames 54 may have different shapes.

[0078] One preferred grid pattern of the grooves 53 is a diagonal grid pattern, as shown in the example of Figures 10 and 11, which is made up of first portions 51a extending in a direction inclined by 40 to 60 degrees (more preferably 45 to 50 degrees) clockwise relative to the front-rear direction LD in plan view, and second portions 51b extending in a direction inclined by 40 to 60 degrees (more preferably 45 to 50 degrees) counterclockwise relative to the front-rear direction LD in plan view. In this case, the shape of the unit frame 54 is generally rhombic. It is particularly preferred that the angle of the first portions 51a and the second portions 51b relative to the front-rear direction LD is 45 degrees.

[0079] The dimensions of the unit frame 54 can be determined as appropriate, but if they are too large, the effect of improving rigidity will be poor, and if they are too small, the frame will be too hard. Therefore, in normal cases, it is preferable that the dimension 54x of the unit frame 54 in the width direction WD be approximately 15 to 20 mm. Also, it is preferable that the dimension 54y of the unit frame 54 in the front-to-rear direction LD be approximately 15 to 20 mm.

[0080] When changing the area ratio of the bottoms 51 of the grooves 53, the width of the bottoms 51 of the grooves 53 can be changed while keeping the pattern of the grooves 53 substantially constant, the pattern of the grooves 53 can be changed while keeping the width 51w of the bottoms 51 of the grooves 53 substantially constant, or both the pattern of the grooves 53 and the width 51w of the bottoms 51 of the grooves 53 can be changed. However, if the width 51w of the bottoms 51 of the grooves 53 is increased to increase the area ratio of the bottoms 51 of the grooves 53, the feel of the hard bottoms 51 of the grooves 53 becomes more easily transmitted to the skin. Therefore, as in the illustrated example, it is preferable to change the pattern of the grooves 53 (specifically, the number of grooves 53 per unit area) while keeping the width 51w of the bottoms 51 of the grooves 53 substantially constant. Furthermore, when the thickness of the bottoms 51 of the grooves 53 in the width direction WD of the absorbent body 56 is changed, the change in shape retention of the absorbent body 56 is not significant, and this has a significant impact on absorption performance such as liquid dispersibility, and also reduces ease of manufacture. Therefore, although it is possible to change the thickness of the bottom 51 of the groove 53 while keeping the area ratio of the bottom 51 of the groove 53 approximately constant, it is more preferable to change the area ratio of the bottom 51 of the groove 53 while keeping the thickness of the bottom 51 of the groove 53 approximately constant.

[0081] 10 to 13 show some preferred examples of groove patterns. In these examples, the width 51w and thickness of the bottom 51 of the groove 53 are approximately constant, but the pattern of the groove 53 varies in the width direction WD so that the area ratio of the bottom 51 of the groove 53 is larger in the side region 56S than in the center region 56C.

[0082] When the grooves 53 have a lattice pattern, the area ratio of the bottoms 51 of the grooves 53 in the side regions 56S can be made higher than that in the center region 56C by combining a plurality of unit frame 54 shapes to form a pattern in which the area of ​​the unit frame 54 gradually decreases from the center in the width direction WD toward both side edges, as shown in Figures 10, 11, and 12. Furthermore, as shown in Figure 13, the area ratio of the bottoms 51 of the grooves 53 in the side regions 56S can be made higher than that in the center region 56C by combining unit frames 54 of the same shape (diamond (square) in the illustrated example) but different sizes.

[0083] The area of ​​each unit frame 54 can be determined as appropriate, but of a pair of unit frames 54 adjacent in the width direction WD so as to share a common side, the area of ​​the larger unit frame 54 is preferably 1.1 to 2.5 times the area of ​​the smaller unit frame 54. Also, the maximum area of ​​the unit frame 54 made up of grooves 53 in the center region 56C is preferably 1.5 to 4 times the maximum area of ​​the unit frame 54 made up of grooves 53 in the side region 56S. In this case, the area of ​​the unit frame 54 made up of grooves 53 in the center region 56C is 150 to 500 mm ２ It is preferable that:

[0084] More specifically, the pattern of the grooves 53 in the example shown in FIGS. 10 and 11 is a diagonal lattice pattern. In this pattern, diamond-shaped first unit frames 54a having the largest area are lined up without gaps in the center of the width direction WD to form a group continuing in the front-to-back direction LD, and along the side edges of the group of first unit frames 54a, rectangular second unit frames 54b, which have one side in common with the first unit frame 54a and whose short side intersecting the common side has a length that is 2 / 3 of the length of the common side, and L-shaped third unit frames 54c, which have two sides in common with the first unit frame 54a and whose short side intersecting the common side has a length that is 2 / 3 of the length of the common side, are lined up without gaps in the group continuing in the front-to-back direction LD, and along the side edges of the group of second unit frames 54b and third unit frames 54c, diamond-shaped fourth unit frames 54d, whose side length is 2 / 3 of the length of one side of the first unit frame 54a, are lined up without gaps in the group continuing in the front-to-back direction LD. In this case, the area of ​​the unit frame 54 of the groove 53 is 4 / 9 at the minimum, assuming that the maximum is 1, which is a smaller change than the two examples described later, but from the viewpoint of ease of manufacturing, this change is preferable.

[0085] 12 also has a diagonal lattice pattern of grooves 53. In this pattern, diamond-shaped first unit frames 54e having the largest area are lined up without gaps in the center of the width direction WD to form a group continuing in the front-to-rear direction LD, and along the side edges of the group of first unit frames 54e, diamond-shaped second unit frames 54f each having a side length half that of the first unit frame 54e and L-shaped third unit frames 54g each having two long sides the same as that of the first unit frame 54e and four short sides half the length of the first unit frame 54e are lined up without gaps in the front-to-rear direction LD, and along the side edges of the group of third unit frames 54g, diamond-shaped second unit frames 54f each having a side length half that of the first unit frame 54e are lined up without gaps in the front-to-rear direction LD. In this case, the maximum area of ​​the unit frames 54e to 54g is 1, and the minimum is 1 / 4.

[0086] The groove 53 pattern in the example shown in Figure 13 is also a diagonal lattice pattern. This pattern includes a group of diamond-shaped first unit frames 54h with the largest area, lined up without gaps in the center of the width direction WD and continuing in the front-to-back direction LD. Along the side edges of the group of first unit frames 54h, a group of diamond-shaped second unit frames 54i with sides half the length of the first unit frame 54h is lined up without gaps in the front-to-back direction LD. Along the side edges of the group of second unit frames 54i, a group of diamond-shaped third unit frames 54j with sides one-third the length of the first unit frame 54h is lined up without gaps in the front-to-back direction LD. In this case, the maximum area of ​​the unit frames 54h-j is 1 / 9, and the minimum area is 1 / 9.

[0087] When the pattern of the grooves 53 is a grid, as in the example shown in Figure 10, if the dimension in the width direction WD of the unit frame 54 in the side region 56S is 0.5 times or less, preferably 0.3 to 0.5 times, the smallest dimension in the width direction WD of the side region 56S, there will be at least one unit frame 54 in the side region 56S, and this is particularly preferable in terms of both improved rigidity and improved diffusion, even if the position of the grid pattern is slightly shifted due to manufacturing errors.

[0088] In this case, as shown in the example of Figure 10, the pattern of the grooves 53 in both side regions 56S consists only of slit adjacent frames 54m consisting of the side edges of the slits 56L and the grooves 53, side edge adjacent frames 54n consisting of the side edges 56e of the absorber 56 and the grooves 53, and complete (without missing parts) unit frames 54 having the same dimensions and shape, and if the area of ​​each slit adjacent frame 54m and the area of ​​each side edge adjacent frame 54n are smaller than the area of ​​the unit frame 54, this is preferable because when the diaper takes on an approximately U-shaped cross-section, the rigidity of the side walls becomes particularly high, making the urine receiving space SP less likely to collapse.

[0089] Of course, in the side region 56S, the area of ​​some or all of the slit adjacent frames 54m (the same applies to the side edge adjacent frames 54n) may be larger than the area of ​​the unit frame 54, as in the examples shown in Figures 12 and 13.

[0090] On the other hand, the pattern of the grooves 53 in the center region 56C preferably has complete (without missing) unit frames 54 having the same dimensions and shape, as in the illustrated example. In this case, as in the illustrated example, a slit adjacent frame 54m may be provided, which is made up of the side edge of the slit 56L and the groove 53.

[0091] Although not shown, by aligning the direction and position of the side edge of the slit 56L with the direction and position of the groove 53, the pattern of the groove 53 in at least one of the side region 56S and the center region 56C can be made into a pattern consisting of only a complete (without missing) unit frame 54.

[0092] On the other hand, the shape of the absorber 56 and the shape of the slits 56L are as described above, but as shown in Figure 14 (a), if both side edges of the absorber 56 extend linearly along the front-to-back direction LD and the pair of slits 56L extend so as to approach the side edges 56e of the absorber 56 from the middle in the front-to-back direction LD toward the front and back, respectively, when the crotch portion M of the diaper has an approximately U-shaped cross section, not only will the side walls easily fit around the inside of the thighs, but the side walls will also become shorter in height toward the front and back and less likely to fold, which has the advantage that the urine receiving space SP in that vicinity will be particularly less likely to collapse.

[0093] <Explanation of Terms Used in the Specification> The following terms used in the specification have the following meanings unless otherwise specified in the specification.

[0094] The "front-to-back direction" refers to the direction indicated by the symbol LD in the figure (vertical direction), and the "width direction" refers to the direction indicated by the symbol WD in the figure (left-to-right direction), and the front-to-back direction and the width direction are perpendicular to each other.

[0095] "Front side" means the side closest to the wearer's skin when worn, and "rear side" means the side farthest from the wearer's skin when worn.

[0096] "Front" means the side closest to the wearer's skin when worn, and "back" means the side farthest from the wearer's skin when worn.

[0097] "Elongation rate" refers to a value when the natural length is 100%. For example, an elongation rate of 200% is equivalent to an elongation ratio of 2 times.

[0098] "Gel strength" is measured as follows: 1.0 g of superabsorbent polymer is added to 49.0 g of artificial urine (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), and the mixture is stirred with a stirrer. The resulting gel is left in a thermo-hygrostat at 40°C and 60% RH for 3 hours, then returned to room temperature, and the gel strength is measured using a curd meter (Curdmeter-MAX ME-500, manufactured by I.techno Engineering).

[0099] - "Basis weight" is measured as follows. After pre-drying the sample or test piece, it is left 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%. Using a sample collection template (100mm x 100mm), a sample measuring 100mm x 100mm is cut from the test piece when it has reached a constant weight. The weight of the sample is measured and multiplied by 100 to calculate the weight per square meter, which is the basis weight.

[0100] The "thickness" of thick members such as the absorber 56, the absorbent element 50, and the bottom 51 of the groove is measured using a thickness measuring device (Peacock, Dial Thickness Gauge, Model H (measurement range 0 to 10 mm, measurement area circular terminal with diameter 10 mm, measurement force approximately 1.7 N, pressure approximately 21.7 KPa)) manufactured by Ozaki Manufacturing Co., Ltd., with the sample and the thickness measuring device positioned horizontally.

[0101] 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: 2 cm ２ Automatic measurement is performed under the following conditions.

[0102] The water absorption amount is measured according to JIS K7223-1996 "Test method for water absorption amount of superabsorbent resins."

[0103] The water absorption rate is the "time to the end point" when 2 g of superabsorbent polymer and 50 g of physiological saline are used and the test is carried out according to JIS K7224-1996 "Test method for water absorption rate of superabsorbent polymers."

[0104] "Deployed state" means a state in which the device is deployed flat without contraction (including any contraction such as contraction due to an elastic member) or slack.

[0105] - "Maximum elongation" means the maximum elongation in the stretch direction in the stretch region (i.e., the elongation at the elastic limit, which is equal to the elongation in the unfolded state), and is expressed as a percentage of the unfolded length, with the natural length being 100%.

[0106] - Unless otherwise specified, the dimensions of each part refer to the dimensions in the unfolded state, not the natural length state.

[0107] - If there is no description of the environmental conditions for a test or measurement, the test or measurement shall be carried out in a test room or device under standard conditions (the test location shall be a temperature of 23±1°C and a relative humidity of 50±2%).

[0108] The present invention can be used for all types of disposable diapers, including not only the pants-type disposable diapers described above, but also tape-type disposable diapers, pad-type disposable diapers, and the like.

[0109] 11...liquid-impermeable sheet, 12A...side seal, 12B...rear outer body, 12F...front outer body, 12H...inner sheet layer, 12S...outer sheet layer, 12X...non-stretchable region, 13...cover nonwoven fabric layer, 14...buttocks cover portion, 15...lower waist elastic member, 16...buttocks cover elastic member, 17...waist elastic member, 200...inner body, 201...fixing region, 30...top sheet, 50...absorbent element, 51... bottom portion, 52... non-compressed portion, 53... groove, 54... unit frame, 54m... slit adjacent frame, 54n... side edge adjacent frame, 56... absorbent body, 56C... center region, 56L... slit, 56S... side region, 58... packaging sheet, 60... side flap, 61... surface portion, 62... back portion, 631-633... gathered elastic member, 631... first gathered elastic member, 632... second gathered elastic member, 6 33...Third gathered elastic member, 64...Liquid-impermeable sheet layer, 65...A non-woven fabric portion, 66...Side nonwoven fabric, 66r...Folded portion, 67...Fixed portion, 70...Side non-stretchable region, 80...Flat gathered region, A1...Intermittent stretch band, A2...Continuous stretch band, B...Rear body portion, BT...Rear waist portion, F...Front body portion, FT...Front waist portion, HM1...First hot melt adhesive, HM2...Second hot melt adhesive adhesive, HM3...third hot melt adhesive, L...middle region, LD...front-to-back direction, M...crotch region, SP...urine receiving space, T...torso region, U...lower waist region, W...waist region, WD...width direction, WO...waist opening, d1...first distance, d2...second distance, d3...third distance, w1...first distance, w2...second distance, w3...width direction dimension of fixing portion, w4...third distance, w5...fourth distance.

Claims

1. An absorbent element having a crotch region and a front portion and a rear portion extending forward and rearward from the crotch region, an absorbent body provided over a range in the front-to-rear direction including the crotch region, and a packaging sheet that wraps the absorbent body, the absorbent body being made by mixing and accumulating pulp fibers and highly absorbent polymer particles, the absorbent body having a pair of elongated slits extending in the front-to-rear direction provided on one side and the other side of the width direction of the crotch region, the absorbent body having a center region defined between one of the slits and the other of the slits, and a pair of side regions defined between the slits on both sides of the width direction and the side edges of the absorbent body, the center region and the side regions having grooves in a continuous pattern in the width direction that extend from at least one of the front and rear surfaces of the absorbent body into the absorbent body and have bottoms compressed in the thickness direction over a range of 60% or more in the front-to-rear direction, The center region has a constant bottom thickness of the groove and a low area ratio of the bottom of the groove, a constant bottom area ratio of the groove and a high bottom thickness, or a low bottom area ratio of the groove and a high bottom thickness, compared to the side regions.

2. The disposable diaper according to claim 1, wherein said center region and said side region are each a region in which said grooves are continuous in a lattice pattern, the thickness and width of the bottom of said grooves in said center region and said side region are the same, and the maximum area of ​​a unit frame consisting of said grooves in said center region is 1.5 to 4 times the maximum area of ​​a unit frame consisting of said grooves in said side region.

3. The absorbent body is made of one or more layers of pulp fibers and highly absorbent polymer particles mixed and accumulated, and the basis weight of the pulp fibers in the absorbent body is 80 to 450 g / m ２ the weight ratio of pulp fibers to highly absorbent polymer particles in the absorbent body is 20:80 to 80:20; the maximum thickness of the absorbent body is 1 to 20 mm; the thickness of the bottom portion is 5 to 40% of the maximum thickness of the absorbent body; the width of the bottom portion is 1 to 3 mm; and the area of ​​the unit frame consisting of the grooves in the center region is 150 to 500 mm ２ The disposable diaper according to claim 2, 4. A disposable diaper as claimed in claim 2 or 3, wherein the grooves are formed in a diagonal lattice pattern consisting of first portions inclined at 40 to 60 degrees clockwise in a plan view with respect to the front-to-rear direction, and second portions inclined at 40 to 60 degrees counterclockwise in a plan view with respect to the front-to-rear direction.

5. The disposable diaper according to claim 2 or 3, wherein the width dimension of said unit frame in said side region is 0.5 times or less the minimum width dimension of said side region.

6. The disposable diaper according to claim 5, wherein the groove pattern in both side regions consists only of a slit adjacent frame consisting of the side edges of the slits and the grooves, a side edge adjacent frame consisting of the side edges of the absorbent body and the grooves, and a complete unit frame having the same dimensions and shape, and the area of ​​each slit adjacent frame and each side edge adjacent frame in both side regions is smaller than the area of ​​the unit frame.

7. A disposable diaper as claimed in claim 1 or 2, wherein both side edges of said absorbent body extend linearly in the front-to-rear direction, and said pair of slits extend so as to approach the side edges of said absorbent body from the middle in the front-to-rear direction towards the front and rear, respectively.

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