JP7499661B2 - Absorbent articles - Google Patents

Description

The present invention relates to improving the fit of the crotch area in absorbent articles equipped with cellular absorbent sheets.

The absorbent article comprises an absorbent body, a liquid-permeable top sheet covering the front side of the absorbent body, and a liquid-impermeable sheet covering the back side of the absorbent body, and excreted liquids such as urine and menstrual blood pass through the top sheet and are absorbed and retained by the absorbent body. As an absorbent body, a mixture of hydrophilic short fibers such as crushed pulp and superabsorbent polymer particles (SAP) stacked into a cotton-like fiber is widely used, but in order to ensure a sufficient amount of absorption while meeting the demands for further thinning, weight reduction, and cost reduction, various types of absorbent sheets (hereinafter also referred to as cellular absorbent sheets) have been proposed that have numerous cells (small chambers) surrounded by the joints of liquid-permeable upper and lower sheets, to which the upper and lower sheets are not joined, and powder containing superabsorbent polymer particles contained within the cells (see, for example, Patent Documents 1 to 6 below).

In conventional cell absorption sheets, when ease of manufacture and manufacturing stability are important, it is desirable for the joints to be formed in a uniform mesh pattern throughout the entire sheet.

However, because the cell absorption sheet is prone to bending along its joints, the absorbent article incorporating it also tends to bend along the joints of the cell absorption sheet. Therefore, if the joints of the cell absorption sheet are formed in a uniform mesh pattern, the absorbent article can bend in any direction at any part, and while it has an excellent fit when worn, there is a risk of it deforming into an unintended shape. This is particularly problematic in the crotch area of the absorbent article. In other words, when the absorbent article is worn sandwiched between the legs, it is easy for the sides of the crotch area to not deform along the wearer's inner thighs, which could cause leakage or a poor fit.

JP 09-504207 A JP 2014-500736 A JP 2011-189067 A Japanese Patent Application Laid-Open No. 10-137291 JP 2017-176507 A JP 2010-522595 A

Therefore, the main objective of the present invention is to improve the fit of the crotch area in absorbent articles equipped with a cellular absorption sheet.

The absorbent article that solves the above problems is as follows.
<First aspect>
A crotch portion is located midway in the front-rear direction,
The device comprises an absorbent body, a liquid-permeable top sheet disposed on the front side of the absorbent body, and a liquid-impermeable sheet disposed on the back side of the absorbent body,
The absorbent body includes a cellular absorbent sheet having upper and lower sheets each having liquid permeability, cells which are portions of the upper and lower sheets that are not joined and are surrounded by the joints of the upper and lower sheets, and powder particles containing superabsorbent polymer particles contained in the cells;
The cell absorption sheet extends across both the front and rear sides of the crotch area,
the cell absorbent sheet has a uniform mesh pattern across the cell absorbent sheet;
On both sides of the portion of the cell absorption sheet located in the crotch area, easy-to-bend portions are provided, the easy-to-bend portions extending linearly along the leg circumference while crossing the joint portion and the cell.
An absorbent article comprising:

(Action and Effect)
This absorbent article follows the basic structure in which the joints of the cell absorption sheet are provided in a uniform net pattern over the entire cell absorption sheet (i.e., retains its advantages), but in addition to these joints, both sides of the part of the cell absorption sheet located in the crotch area are provided with easy-to-fold parts that cross the joints and the cells and follow the leg circumference. This makes it easier for both sides of the part of the cell absorption sheet located in the crotch area to bend to the front side along the easy-to-fold parts, rather than the joints for forming the cells. Therefore, when the absorbent article is worn between the legs, both sides of the crotch area are easily deformed into a desired shape along the wearer's inner thighs, making it less likely to cause leakage or poor fit.

<Second aspect>
The upper sheet and the lower sheet are each made of a nonwoven fabric,
the joints are provided intermittently in a circumferential direction of the cell, and are formed by welding the upper sheet and the lower sheet while applying pressure in a thickness direction,
the easy-to-bend portion is a portion in which a welded portion formed by welding the upper sheet and the lower sheet while pressing them in a thickness direction is intermittently provided along the leg periphery,
The width of the welded portion in the easy-to-bend portion is wider than the width of the joint portion, and the interval between the welded portions in the easy-to-bend portion is narrower than the interval between the joint portions.
The absorbent article of the first aspect.

(Action and Effect)
When the joints are provided intermittently in the circumferential direction of the cell and are formed by welding the upper and lower sheets while applying pressure in the thickness direction, the easily bendable portion can be formed by arranging similar welds along the leg circumference. In this case, as in this embodiment, it is preferable that the width of the welds in the easily bendable portion is wider than the width of the joints and the interval between the welds in the easily bendable portion is narrower than the interval between the joints, because this makes it easier to bend along the easily bendable portion. Of course, the easily bendable portion can also be formed by applying non-heated embossing or creasing to the cell absorption sheet, or by perforation.

<Third aspect>
the joints are provided intermittently in a circumferential direction of the cell, and are formed by welding the upper sheet and the lower sheet while applying pressure in a thickness direction,
the welded portion of the easily bendable portion is not peeled off due to the expansion force of the highly absorbent polymer particles in the adjacent cells;
The cell through which the easy-to-bend portion passes and the cells located to the side of the easy-to-bend portion do not contain superabsorbent polymer particles or are low-content cells having a lower content of superabsorbent polymer particles than adjacent cells on the inner side in the width direction of the cell.
The absorbent article according to the first or second aspect.

(Action and Effect)
When the easy-to-fold portion is formed by the welded portion of the upper sheet and the lower sheet, it is preferable that the easy-to-fold portion does not peel off due to the expansion force of the superabsorbent polymer particles in the adjacent cells, since the effect of the easy-to-fold portion is exerted even after the absorption of excrement. In addition to this or instead, it is preferable that the cell through which the easy-to-fold portion passes and the cells located to the side of it are low-absorbent cells, since it is difficult to generate a situation in which the portions on both sides of the easy-to-fold portion expand and press against each other, thereby hindering folding along the easy-to-fold portion (force acts in the direction of flattening).

<Fourth aspect>
the joints are provided intermittently in a circumferential direction of the cell, and are formed by welding the upper sheet and the lower sheet while applying pressure in a thickness direction,
the welded portion of the easily bendable portion is not peeled off due to the expansion force of the highly absorbent polymer particles in the adjacent cells;
a portion of the lower sheet located in each cell is pushed downward to form a pair of concave and convex portions on the upper and lower surfaces of the lower sheet,
The portion of the upper sheet located in each cell is not extruded in the thickness direction and is flat.
The absorbent article according to any one of the first to third aspects.

(Action and Effect)
In the cell absorption sheet, in order to secure the volume when the internal high-absorbent polymer particles absorb and expand, it is preferable that at least one of the upper sheet and the lower sheet has a recess in which the portion located at each cell is pushed outward in the thickness direction. However, if the upper sheet has a recess recessed upward, when the high-absorbent polymer particles absorb and expand, the portions on both sides of the easy-to-bend portion expand and press against each other, hindering folding along the easy-to-bend portion (force acts in the direction of flattening). On the other hand, if only the lower sheet has a recess recessed downward as in this embodiment, such a problem does not occur, so it is preferable.

<Fifth aspect>
The cell absorption sheet is not joined to any of the upper, lower, or laterally adjacent members at any of the entire portions of the cell absorption sheet that are located to the side of the easy-to-fold portion.
The absorbent article according to any one of the first to fourth aspects.

(Action and Effect)
In the present embodiment, the entire portion of the cell absorption sheet to the side of the easy-to-bend portion is not restrained by the adjacent members above, below and to the side, so that the bending action along the easy-to-bend portion described above is easily achieved.

<Sixth aspect>
The cell absorption sheet has a constant width throughout the front-to-rear direction.
The absorbent article according to any one of the first to fifth aspects.

(Action and Effect)
It is preferable that the cell absorption sheet has a constant width over the entire front-to-rear direction because it is easy to manufacture, but this tends to cause problems with the fit of the crotch area as described above. Therefore, the easy-to-fold portion described above is particularly significant when applied to such a cell absorption sheet.

The present invention provides the advantage of improving the fit of the crotch area in absorbent articles equipped with a cellular absorption sheet.

FIG. 2 is a plan view showing the inner surface of the tape-type disposable diaper in an unfolded state. FIG. 2 is a plan view showing the outer surface of the tape-type disposable diaper in an unfolded state. This is a cross-sectional view of FIG. This is a cross-sectional view taken along line 7-7 of FIG. 1A is a cross-sectional view taken along line 8-8 of FIG. 1, and FIG. This is a cross-sectional view of FIG. 1 along line 5-5. FIG. 1A is a bottom cutaway view of a main part of the absorbent body, and FIG. FIG. FIG. 2-2 cross-sectional view of Figures 8 and 9. FIG. 2 is a plan view of an absorbent body, with joints shown in a simplified manner. 1A to 1C are schematic plan views showing various examples of cell arrangements. 1A to 1C are cross-sectional views of various cell absorption sheets. 1A to 1C are cross-sectional views of various cell absorption sheets. FIG. 1 is a cross-sectional view showing a main part of an absorbent body. FIG. 2 is a cross-sectional view showing the layer structure of an absorbent body and a packaging sheet. FIG. 4 is a cross-sectional view showing the change upon absorption. FIG. 2 is a cross-sectional view showing a schematic layer structure of a highly absorbent nonwoven fabric. 4 is a cross-sectional view showing a folded state of the easy-to-fold portion. FIG.

Below, as an example of an absorbent article, a tape-type disposable diaper will be described with reference to the attached drawings. Figures 1 to 6 show an example of a tape-type disposable diaper having a crotch area M located in the middle in the front-to-rear direction LD. The symbol X in the figures indicates the overall width of the diaper excluding the fastening tape, and the symbol L indicates the overall length of the diaper. When the product has a narrower constricted area in the middle in the front-to-rear direction LD than the front and rear sides as in the illustrated example, the crotch area M refers to the range in the front-to-rear direction LD that includes this constricted area. When the product does not have such a constricted area, it refers to the part located in the center of the front-to-rear direction LD, and whose dimension in the front-to-rear direction LD is 20 to 40% of the overall length of the product.

The illustrated example of the tape-type disposable diaper has a basic structure in which an absorbent 70 is interposed between a liquid-permeable top sheet and a liquid-impermeable sheet located on the back side. This tape-type disposable diaper also has end flaps EF that extend to the front and rear of the absorbent 70 and are not provided with the absorbent 70, and a pair of side flaps SF that extend laterally beyond the side edges of the absorbent 70. Both side edges of the side flaps SF are narrowed to fit around the legs, but may be straight. The side flaps SF in the back portion B are each provided with a fastening tape 13, and when putting on the diaper, the side flaps SF of the back portion B are overlapped on the outside of the side flaps SF of the abdominal portion F, and the fastening tape 13 is fastened in an appropriate position on the outer surface of the abdominal portion F.

In addition, in this tape-type disposable diaper, the entire outer surface except for the fastening tape 13 is formed of the exterior nonwoven fabric 12. In particular, in the region including the absorbent 70, the liquid-impermeable sheet 11 is fixed to the inner surface side of the exterior nonwoven fabric 12 with an adhesive such as a hot melt adhesive, and the absorbent 70, the intermediate sheet 40, and the top sheet 30 are laminated in this order on the inner surface side of the liquid-impermeable sheet 11. In the illustrated example, the top sheet 30 and the liquid-impermeable sheet 11 are rectangular and have dimensions slightly larger than the absorbent 70 in the front-rear direction LD and the width direction WD, and the peripheral portion of the top sheet 30 that protrudes beyond the side edge of the absorbent 70 and the peripheral portion of the liquid-impermeable sheet 11 that protrudes beyond the side edge of the absorbent 70 are joined with a hot melt adhesive or the like. The liquid-impermeable sheet 11 is also formed to be slightly wider than the top sheet 30.

Furthermore, on both sides of the width of this tape-type disposable diaper, rise-up gathers 60 are provided that rise up toward the wearer's skin, and the gather sheets 62 that form these rise-up gathers 60 are fixed in the range from both sides of the top sheet 30 to the inner surface of each side flap SF.

The components adjacent in the thickness direction are fixed or joined as necessary in the same manner as known diapers, except for the fixing or joining parts described below. The dotted parts in the cross-sectional view show adhesives such as hot melt adhesives 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 using a letterpress method). Alternatively or in addition to this, in the fixing part of the elastic member, hot melt adhesive can be applied to the outer 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), olefin-based, polyester/polyamide-based, and other types are available, but they can be used without any particular limitation. As a fixing or joining means for joining each component, material welding means such as heat sealing and ultrasonic sealing can also be used. In the part where liquid permeability in the thickness direction is required, the components adjacent 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 such as a spiral, Z-shape, or wave pattern can be suitably used, and when coating an area greater than the coating width of one nozzle, intermittent pattern coating such as a spiral, Z-shape, or wave pattern can be performed with or without gaps in the width direction.

The details of each part will be described below in order. In the following description, the nonwoven fabric may be any known nonwoven fabric depending on the part and purpose. The fibers constituting the nonwoven fabric may be selected without particular limitation from synthetic fibers such as olefins, polyesters, polyamides, etc. (including single-component fibers as well as composite fibers such as core-sheath fibers), such as polyethylene or polypropylene, regenerated fibers such as rayon or cupra, natural fibers such as cotton, etc., and may be mixed and used. In order to increase the flexibility of the nonwoven fabric, it is preferable to use crimped fibers as the constituent fibers. The fibers constituting the nonwoven fabric may be hydrophilic fibers (including fibers that have been made hydrophilic by a hydrophilizing agent), hydrophobic fibers, or water-repellent fibers (including fibers that have been made water-repellent by a water-repellent agent). In addition, 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 punch nonwoven fabrics, point bond nonwoven fabrics, laminated nonwoven fabrics (SMS nonwoven fabrics with a meltblown layer sandwiched between spunbond layers, SMMS nonwoven fabrics, etc.) depending on the fiber length, sheet formation method, fiber bonding method, and laminated structure, but any of these nonwoven fabrics can be used.

(Outer nonwoven fabric)
The exterior nonwoven fabric 12 constitutes the outer surface of the product and is intended to give the outer surface of the product a cloth-like appearance and feel. The fiber weight of the exterior nonwoven fabric is preferably 10 to 50 g/m ² , and more preferably 15 to 30 g/m ^2. The exterior nonwoven fabric 12 may be omitted, in which case the liquid-impermeable sheet 11 may be formed in the same shape as the exterior nonwoven fabric 12 to constitute the outer surface of the product.

(Liquid-impermeable sheet)
The material of the liquid-impermeable sheet 11 is not particularly limited, but examples thereof include olefin resins such as polyethylene and polypropylene, laminated nonwoven fabrics in which nonwoven fabrics are laminated on polyethylene sheets, etc., and nonwoven fabrics in which a waterproof film is interposed to ensure substantial liquid impermeability (in this case, the waterproof film and the nonwoven fabric constitute the liquid-impermeable sheet). Of course, in addition to these, examples of materials having liquid impermeability and moisture permeability that have been favorably used in recent years from the viewpoint of preventing stuffiness can also be exemplified. Examples of sheets made of materials having liquid impermeability and moisture permeability include, for example, microporous sheets obtained by kneading an inorganic filler into an olefin resin such as polyethylene or polypropylene, forming a sheet, and then stretching the sheet in a uniaxial or biaxial direction. Furthermore, sheets that have been made liquid impermeable without using a waterproof film by methods such as nonwoven fabrics using microdenier fibers, strengthening leak prevention by applying heat or pressure to reduce the voids in the fibers, and coating with a highly water-absorbent resin or a hydrophobic resin or a water-repellent agent can also be used as the liquid-impermeable sheet 11.

(Top sheet)
The top sheet 30 is liquid-permeable, and examples of such materials include a perforated or non-perforated nonwoven fabric, a perforated plastic sheet, etc. Both side portions of the top sheet 30 may be folded back onto the back side of the absorbent body 70, or may extend beyond the side edges of the absorbent body 70 without being folded back, as in the illustrated example.

The top sheet 30 is preferably fixed to the adjacent backside member by a joining means such as heat sealing or ultrasonic sealing, or by a hot melt adhesive, in order to prevent misalignment relative to the backside member. In the illustrated example, the top sheet 30 is fixed to the front surface of the intermediate sheet 40 and the front surface of the portion of the packaging sheet 45 that is located on the front side of the absorbent body 70 by a hot melt adhesive applied to the backside of the top sheet 30.

(middle seat)
The intermediate sheet 40 is joined to the back surface of the top sheet 30 in order to quickly move excreted liquid that has passed through the top sheet 30 to the absorbent body 70 and to prevent backflow. The intermediate sheet 40 and the top sheet 30 can be joined using a hot melt adhesive, heat embossing or ultrasonic welding.

As the intermediate sheet 40, in addition to using nonwoven fabric, a resin film having a large number of through holes can also be used. As the nonwoven fabric, the same material as that of the top sheet 30 can be used, but a material having a higher hydrophilicity than the top sheet 30 or a higher fiber density is preferable because it has excellent liquid transfer characteristics from the top sheet 30 to the intermediate sheet 40. For example, an air-through nonwoven fabric can be suitably used as the intermediate sheet 40. For the air-through nonwoven fabric, it is preferable to use composite fibers with a core-sheath structure, and in this case, the resin used for the core may be polypropylene (PP), but polyester (PET) with high rigidity is preferable. The basis weight is preferably 17 to 80 g/m ² , and more preferably 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 with no core in the center, hollow fibers, or eccentric and hollow fibers as the mixed fibers of all or part of the raw fiber.

In the illustrated example, the intermediate sheet 40 is positioned in the center and is shorter than the width of the absorbent 70, but it may be provided across the entire width. The dimension of the intermediate sheet 40 in the front-to-rear direction LD may be the same as the overall length of the diaper, the same as the dimension of the absorbent 70, or within a short length range centered on the area that receives liquid.

(Rise and gather)
In order to prevent lateral movement of excrement on the topsheet 30 and prevent lateral leakage, it is preferable to provide rising gathers 60 that protrude (stand up) from the inner surface of the product on both sides in the width direction WD.

The rising gathers 60 are composed of a gather sheet 62 and an elongated gather elastic member 63 fixed in a stretched state along the front-to-rear direction LD to the gather sheet 62. A water-repellent nonwoven fabric can be used as the gather sheet 62, and rubber thread or the like can be used as the elastic member 63. As shown in Figures 1 and 3, multiple elastic members can be provided on each side, or one elastic member can be provided on each side.

The inner surface of the gathered sheet 62 has a bonding start end in the width direction WD on the side of the top sheet 30, and the portion outside the bonding start end in the width direction WD is bonded with a hot melt adhesive or the like to the side of the liquid-impermeable sheet 11 and the side of the exterior nonwoven fabric 12 located in that portion.

Around the legs, the inside of the fixing start point of the rising gathers 60 in the width direction WD is fixed to the top sheet 30 at both ends in the front-to-rear direction LD of the product, but the part between them is an unfixed free part, and this free part stands up due to the contraction force of the elastic members 63. When the diaper is put on, the diaper is put on the body in a boat shape, and the contraction force of the elastic members 63 acts, so the rising gathers 60 stand up due to the contraction force of the elastic members 63 and fit closely around the legs. As a result, so-called side leakage from around the legs is prevented.

Unlike the illustrated example, both ends of the gathered sheet 62 in the front-to-rear direction LD at the inner part in the width direction WD can be fixed in a folded state with a base end part extending inward from the outer part in the width direction WD and a tip end part that is folded back from the edge on the center side in the width direction WD of this base end part towards the body and extends outward in the width direction WD, and the part in between can be an unfixed free part.

(Flat gathers)
1 to 3, on the outer side of the width direction WD near the fixing start end of the fixed portion of the gathered sheet 62, leg elastic members 64 made of elongated elastic members such as rubber thread are fixed in a stretched state in the front-to-rear direction LD between the gathered sheet 62 and the liquid-impermeable sheet 11, so that the leg portions of each side flap SF are configured as flat gathers. The leg elastic members 64 can also be disposed between the liquid-impermeable sheet 11 and the exterior nonwoven fabric 12 of the side flap SF. The leg elastic members 64 can be provided in multiple pieces on each side as in the illustrated example, or only one piece on each side.

(Fastening tape)
1, 2 and 6, the fastening tape 13 has a sheet base material constituting a tape attachment portion 13C fixed to the side of the diaper, a tape main body portion 13B protruding from the tape attachment portion 13C, and a fastening portion 13A for the abdominal side provided at the middle of the tape main body portion 13B in the width direction WD of the sheet base material, and the portion on the tip side of the fastening portion 13A is a gripping portion. The tape attachment portion 13C of the fastening tape 13 is sandwiched between the gathered sheet 62 constituting the inner layer of the side flap SF and the exterior nonwoven fabric 12 constituting the outer layer, and is adhered to these sheets by a hot melt adhesive. The fastening portion 13A is also fixed to the sheet base material by an adhesive.

The hook material (male material) of a mechanical fastener (hook-and-loop fastener) is suitable for the fastening portion 13A. The hook material has a number of engaging protrusions on its outer surface. The engaging protrusions can be shaped like a square, a J-shape, a mushroom shape, a T-shape, a double J-shape (a shape in which two J-shapes are joined back to back), etc., and any shape is acceptable. Of course, an adhesive layer can also be provided as the fastening portion of the fastening tape 13.

The sheet base material forming the tape attachment portion 13C to the tape main body portion 13B can be made of various nonwoven fabrics such as spunbond nonwoven fabric, air-through nonwoven fabric, spunlace nonwoven fabric, etc., as well as plastic film, polylaminated nonwoven fabric, paper, or composite materials of these.

(Target sheet)
It is preferable to provide a target sheet 12T having a target for facilitating the fastening at the fastening portion of the fastening tape 13 in the abdominal portion F. When the fastening portion 13A is a hook material, the target sheet 12T may be a sheet base material made of a plastic film or nonwoven fabric on which a large number of loop threads are provided so that the hook material can be entangled. When the fastening portion 13A is an adhesive layer, the target sheet 12T may be a sheet base material made of a smooth plastic film with a high adhesiveness, the surface of which is subjected to a peeling treatment. When the fastening portion of the fastening tape 13 in the abdominal portion F is made of a nonwoven fabric, for example, when the exterior nonwoven fabric 12 in the illustrated example is made of a nonwoven fabric and the fastening portion 13A of the fastening tape 13 is made of a hook material, the target sheet 12T may be omitted and the hook material may be entangled with the nonwoven fabric of the exterior nonwoven fabric 12 to be fastened. In this case, the target sheet 12T may be provided between the exterior nonwoven fabric 12 and the liquid-impermeable sheet 11.

(Absorber)
As shown in Figures 1, 3, 5, 15 and 16, the absorbent 70 is a portion that absorbs and retains the liquid content of excrement, and has an upper auxiliary layer 71 provided at the top and a main absorbent layer 72 provided on the back side thereof. As will be described later, it is preferable to have the upper auxiliary layer 71 on the main absorbent layer 72, but the upper auxiliary layer 71 can be omitted. Figure 16 shows the layer structure of the absorbent 70 in Figure 15 in an easily understandable manner, with the layers separated. The absorbent 70 can be bonded to a member on at least one of the front and back sides via an adhesive 50h such as a hot melt adhesive.

(Upper auxiliary layer)
The upper auxiliary layer 71 has a highly absorbent nonwoven fabric 42 with a Klemm absorbency of 100 mm or more, the surface of which is exposed to the uppermost surface of the absorbent body 70. This highly absorbent nonwoven fabric 42 can rapidly absorb and diffuse even viscous liquids. This can significantly improve the absorbency of viscous liquids by the absorbent body 70. It is particularly preferable that the highly absorbent nonwoven fabric 42 has a Klemm absorbency of 130 mm or more. In addition, the upper limit of the Klemm absorbency of the highly absorbent nonwoven fabric 42 is not particularly limited, but is preferably about 180 mm, and is particularly preferably 160 mm.

The water retention capacity under load of the highly absorbent nonwoven fabric 42 of the upper auxiliary layer 71 is preferably greater than 0 g and less than 0.15 g, and more preferably greater than 0 g and less than 0.12 g. The water retention capacity under no load of the highly absorbent nonwoven fabric 42 of the upper auxiliary layer 71 is preferably greater than 0 g and less than 0.7 g, and more preferably greater than 0 g and less than 0.3 g.

The highly absorbent nonwoven fabric 42 is not limited by the material and manufacturing method, but is preferably a wet nonwoven fabric (particularly a wet spunlace nonwoven fabric) containing 50% or more of pulp fiber or rayon fiber and having a basis weight of 25 to 50 g/m ^2. As fibers other than pulp fiber or rayon fiber, synthetic fibers such as olefin-based, polyester-based, and polyamide-based fibers such as polyethylene or polypropylene (including single-component fibers as well as composite fibers such as core-sheath fibers) can be used. The use of such a wet nonwoven fabric is preferable because it can rapidly absorb and diffuse viscous liquids due to the capillary phenomenon caused by the minute fiber gaps. In particular, such a wet nonwoven fabric not only has a high Klemm absorbency, but is also very thin and flexible, so that the decrease in flexibility and the increase in thickness of the absorber 70 as a whole can be suppressed. The thickness of the highly absorbent nonwoven fabric 42 is not limited, but in the case of the above basis weight, it is preferably about 0.13 to 0.48 mm.

As shown in Figure 18, a two-layer or three-layer or more nonwoven fabric having a support layer 42b containing long fibers of synthetic resin and a pulp layer 42a located on the outermost side and consisting only of pulp fibers is particularly suitable as the highly absorbent nonwoven fabric 42. Such highly absorbent nonwoven fabric 42 has high Klemm absorbency due to the pulp layer 42a, while the strength can be increased due to the presence of the support layer 42b, so that it has excellent durability when provided at the top of the absorbent body 70.

When the upper auxiliary layer 71 has the first superabsorbent polymer particles 43 adjacent to the back surface of the superabsorbent nonwoven fabric 42, the viscous liquid N absorbed and diffused by the superabsorbent nonwoven fabric 42 can be gradually absorbed and retained by the superabsorbent polymer particles adjacent to the back surface of the superabsorbent nonwoven fabric 42, as shown by the arrows in FIG. 17(a). This can significantly improve the absorbency of the viscous liquid N. In particular, if the superabsorbent nonwoven fabric 42 of the upper auxiliary layer 71 is the above-mentioned wet nonwoven fabric, this is preferable because it facilitates the transfer of the viscous liquid N to the first superabsorbent polymer particles 43 adjacent to the back surface.

The dimensions and arrangement of the highly absorbent nonwoven fabric 42 of the upper auxiliary layer 71 can be determined as appropriate. For example, as shown in the illustrated example, the highly absorbent nonwoven fabric 42 may be arranged to cover the entire surface of the main absorbent layer 72, or may be arranged to cover only a portion of the surface of the main absorbent layer 72, such as the front end, rear end, center, or a plurality of these. The highly absorbent nonwoven fabric 42 may have a portion that protrudes from the periphery of the main absorbent layer 72, or a portion or all of the periphery of the highly absorbent nonwoven fabric 42 may be spaced toward the center from the periphery of the main absorbent layer 72. In general, it is desirable for the highly absorbent nonwoven fabric 42 of the upper auxiliary layer 71 to cover 90% or more of the area of the main absorbent layer 72.

The dimensions and arrangement of the area having the first superabsorbent polymer particles 43 can be determined as appropriate. For example, as shown in the illustrated example, the first superabsorbent polymer particles 43 may be arranged in the entire area where the superabsorbent nonwoven fabric 42 and the main absorbent layer 72 overlap, or they may be arranged only in a part of the area where the superabsorbent nonwoven fabric 42 and the main absorbent layer 72 overlap, such as the front end, rear end, center, or multiple of these. In normal cases, it is desirable for the area having the first superabsorbent polymer particles 43 to occupy 83% or more of the area of the main absorbent layer 72.

The first superabsorbent polymer particles 43 do not have to be fixed to the superabsorbent nonwoven fabric 42, but it is preferable that they are fixed. The first superabsorbent polymer particles 43 can be adhered to the superabsorbent nonwoven fabric 42 by, for example, an adhesive 42h such as a hot melt adhesive applied in an intermittent pattern to the back surface of the superabsorbent nonwoven fabric 42.

The first superabsorbent polymer particles 43 may be fixed to the surface of the main absorbent layer 72, but may not be fixed thereto. For example, an adhesive 43h such as a hot melt adhesive may be applied to the surface of the main absorbent layer 72 in an intermittent pattern, and then the first superabsorbent polymer particles 43 may be scattered on the applied portion, and the superabsorbent nonwoven fabric 42 may be placed on top of the first superabsorbent polymer particles 43 with or without the adhesive 42h.

The basis weight of the first superabsorbent polymer particles 43 can be appropriately determined, but assuming a viscous liquid that requires a small amount of absorption at one time, such as the liquid in muddy stool, watery stool, or soft stool, it is preferably 50 to 150 g/m ² , and particularly preferably 50 to 100 g/m ^2. If the basis weight of the first superabsorbent polymer particles 43 is less than 50 g/m ² , it may be difficult to sufficiently absorb even a small amount of viscous liquid. In addition, if the basis weight of the first superabsorbent polymer particles 43 exceeds 150 g/m ² , when absorbing a large amount of non-viscous liquid such as urine, gel blocking occurs after the first superabsorbent polymer particles 43 fully absorbs and expands, and the supply of non-viscous liquid to the main absorbent layer 72 is likely to be hindered. On the other hand, if it is within the above range, even after the first superabsorbent polymer particles 43 fully absorbs and expands, there will be a portion where gel blocking does not occur, and the supply of non-viscous liquid to the main absorbent layer 72 will be ensured, which is preferable.

(Main absorption layer: Cell absorption sheet)
As shown in the figure, the main absorbent layer 72 is a cell absorption sheet 50 in which second superabsorbent polymer particles 53 are contained in the cells 55, and extends across both the front and back of the crotch area M. Since the absorption performance of the cell absorption sheet 50 depends on the second superabsorbent polymer particles 53, it inevitably has a slow absorption speed and low absorbency of the viscous liquid N. Therefore, the above-mentioned upper auxiliary layer 71 is particularly significant when such a cell absorption sheet 50 is used as the main absorbent layer 72.

The overall width of the cell absorption sheet 50 (i.e., the overall width of the wider of the upper sheet 51 and the lower sheet 52; if the overall widths of the upper sheet 51 and the lower sheet 52 are the same, the overall widths of both sheets) is preferably constant throughout the entire front-to-rear direction LD in order to facilitate manufacturing and to avoid generating waste material due to cutting.

The cell absorption sheet 50 will be described in more detail. As shown in enlarged views in Figs. 7 and 15, the cell absorption sheet 50 has an upper sheet 51, a lower sheet 52 arranged on the back side of the upper sheet 51, cells (small chambers) 55 that are surrounded by joints 54 between the upper sheet 51 and the lower sheet 52 and are the non-jointed portions of the upper sheet 51 and the lower sheet 52, and second superabsorbent polymer particles 53 contained within the cells 55. A large number of cells 55 are arranged at intervals corresponding to the joints 54. In this way, the second superabsorbent polymer particles 53 are distributed and held in a large number of cells 55 that are entirely surrounded by the joints 54, thereby preventing uneven distribution of the second superabsorbent polymer particles 53 in the cell absorption sheet 50.

In order to facilitate the arrangement of the second superabsorbent polymer particles 53 during manufacturing and to ensure the volume after absorption and expansion, it is preferable that at least one of the upper sheet 51 and the lower sheet 52 in the cell 55 has a recess 50c that is recessed to the outside of the cell 55 in the unfolded state, but it is also possible that the second superabsorbent polymer particles 53 are simply sandwiched between the upper sheet 51 and the lower sheet 52 without having the recess 50c.

The recesses 50c can be formed by subjecting the target sheet to a shaping process such as embossing. This embossing process also results in the formation of outwardly bulging protrusions 50p in the portions of the target sheet that correspond to each cell 55. In other words, when the recesses 50c are formed in the upper sheet 51 by embossing, the portions of the upper sheet 51 that correspond to each cell 55 are pushed upward, forming the upwardly bulging protrusions 50p. There are no particular limitations on the depth 50d of the recesses 50c, but it is preferable that it be approximately 1.0 to 7.0 mm, and in particular 1.0 to 5.0 mm.

When absorbing a non-viscous liquid U such as urine, if the first superabsorbent polymer particles 43 of the upper auxiliary layer 71 are uniformly arranged, the first superabsorbent polymer particles 43 will preferentially absorb and expand, and the expanded first superabsorbent polymer particles 43 will adhere to each other to form a layer that is difficult to permeate liquid, which may cause gel blocking, making it difficult to supply the non-viscous liquid U to the main absorbent layer 72. In other words, the upper auxiliary layer 71 may hinder absorption by the main absorbent layer 72. In contrast, as shown in Figure 15, the portions located in each cell 55 of the upper sheet 51 form convex portions 50p that bulge upward, the first superabsorbent polymer particles 43 are fixed to the upper surface of the upper sheet 51 of the main absorbent layer 72, and the amount (basis weight) of the first superabsorbent polymer particles 43 attached to the upper surface of the upper sheet 51 increases from the top of the convex portions 50p to the bottom of the valley portions located between adjacent convex portions 50p. As shown in Figure 17(a), the first superabsorbent polymer particles 43 fixed to the upper surface of the upper sheet 51 can be effectively used to absorb the viscous liquid N. However, when compared with the amount of first superabsorbent polymer particles used, as shown in Figure 17(b), even after the first superabsorbent polymer particles 43 have sufficiently absorbed and expanded when absorbing the non-viscous liquid U, gel blocking is less likely to occur in the portions where the amount of the first superabsorbent polymer particles 43 attached is less likely to be impeded, and the supply of the non-viscous liquid U to the main absorbent layer 72 is less likely to be hindered. In addition, by utilizing the convex portions 50p of the upper sheet 51, it becomes easy to provide a regular variation in the amount of the first superabsorbent polymer particles 43 attached to the upper surface of the upper sheet 51 (alternating between areas with a large amount and areas with a small amount). That is, as described above, when the hot melt adhesive is applied to the surface of the main absorbent layer 72 in an intermittent pattern and then the first superabsorbent polymer particles 43 are scattered on the applied portion, even if the adhesive is evenly scattered, the first superabsorbent polymer particles 43 tend to roll down toward the bottom of the valley due to gravity, so that the amount of the first superabsorbent polymer particles 43 naturally increases from the top of the convex portion 50p toward the bottom of the valley located between the adjacent convex portions 50p. Therefore, although such a non-uniform attachment structure of the first superabsorbent polymer particles 43 appears to be a complex structure at first glance, it is relatively easy to manufacture. It goes without saying that even in this case, it is preferable that the basis weight of the first superabsorbent polymer particles 43 is within the above-mentioned range.

When the amount of the first superabsorbent polymer particles 43 attached to the upper surface of the upper sheet 51 increases from the top of the convex portion 50p toward the bottom of the valley portion located between adjacent convex portions 50p, the first superabsorbent polymer particles 43 may not be attached to a part of the convex portion 50p, including the top, and the first superabsorbent polymer particles 43 may be attached only to the other parts, or, as shown in the illustrated example, the first superabsorbent polymer particles 43 may be attached to almost the entire convex portion 50p, including the top and other parts, and the amount of attachment may increase continuously (or stepwise) toward the bottom of the valley portion.

The dimensions of the convex portion 50p can be determined as appropriate, but from this perspective, it is preferable that the dimension 55L in the front-to-rear direction LD of the convex portion 50p of the upper sheet 51 is 6 to 30 mm, the dimension 55W in the width direction WD of the convex portion 50p of the upper sheet 51 is 7 to 50 mm, the width 54W of the joint portion 54 is 1.0 to 1.8 mm, and the depth 50d of the valley portion of the upper sheet 51 (the height of the convex portion 50p) is 1.0 to 7.0 mm.

If the upper sheet 51 is provided with a recess 50c, a protrusion 50p is formed on the upper surface of the upper sheet 51, which makes it difficult to adhere to the superabsorbent nonwoven fabric 42 of the upper auxiliary layer 71 (gaps are easily generated), and there is a risk that the transfer of the viscous liquid N from the superabsorbent nonwoven fabric 42 to the first superabsorbent polymer particles 43 may be hindered. Therefore, from this point of view, as shown in FIG. 13(c), it is also preferable not to form a recess 50c on the upper sheet 51 (i.e., to have a flat upper surface that has not been subjected to shaping processing), but to form a recess 50c in the portion constituting each cell 55 in the lower sheet 52. As a result, while the recess 50c of the lower sheet 52 ensures the expansion volume of the second superabsorbent polymer particles 53, the upper surface of the upper sheet 51 and the first superabsorbent polymer particles 43 arranged thereon are easily adhered to the superabsorbent nonwoven fabric 42 of the upper auxiliary layer 71, and the transfer of the viscous liquid N from the superabsorbent nonwoven fabric 42 to the first superabsorbent polymer particles 43 is less likely to be hindered.

On the other hand, as shown in Fig. 7(b) and Fig. 13(a), it is preferable that a middle sheet 80 made of nonwoven fabric is interposed between the upper sheet 51 and the lower sheet 52, but as shown in Fig. 14(b), the middle sheet 80 may not be provided. When the middle sheet 80 is provided, the upper sheet 51, the middle sheet 80, and the lower sheet 52 are joined at the joint 54. It is also preferable that the middle sheet 80 is compressed in the thickness direction at the joint 54 and expands into the recess 50c at the cell 55 (in other words, the fiber density decreases the further away from the joint). This makes it difficult for the recess 50c (and therefore the protrusion) to be crushed by pressure applied when the product is packaged or when it is worn, and even if it is crushed, the elasticity of the middle sheet 80 promotes shape restoration to at least the part where the middle sheet 80 was inserted or a volume close to it. During the absorption of excreted liquid, the superabsorbent polymer expands the gaps between the fibers of the middle sheet 80 and can expand while penetrating therein, or while easily compressing the middle sheet 80, or by both, so the presence of the middle sheet 80 is unlikely to hinder the expansion of the second superabsorbent polymer particles 53. Furthermore, the fibers of the middle sheet 80 that spread within the recesses 50c ensure a liquid passage to each of the second superabsorbent polymer particles 53, so that even after the second superabsorbent polymer particles 53 start to expand, the decrease in diffusivity is suppressed and gel blocking is unlikely to occur. Therefore, the synergistic effect of these factors improves the absorption speed (especially in the early stages of absorption) of a disposable diaper equipped with the present cell absorbent sheet 50.

The upper sheet 51 is not particularly limited as long as it is made of a liquid-permeable material like the top sheet 30. Since the upper sheet 51 affects the absorption rate, a dry nonwoven fabric made of hydrophilic fibers, particularly natural fibers such as cotton and pulp, is particularly suitable for the upper sheet 51. Among them, an air-laid pulp nonwoven fabric containing 70% by weight or more of pulp (if less than 100% by weight, the remaining amount can be an appropriate synthetic fiber) is particularly suitable for the upper sheet 51. The fiber bonding method of the nonwoven fabric is not particularly limited, but in order to prevent the second superabsorbent polymer particles 53 from being detached, a bonding method that increases the fiber density, such as a spunbond method, a meltblown method, or a needle punch method, is preferred. In addition, the fineness, basis weight, and thickness of the nonwoven fabric are preferably about 2.0 to 7.0 dtex, about 18 to 50 g/m ² , and about 0.10 to 0.60 mm, respectively. When a perforated plastic sheet is used, the diameter of the openings is preferably smaller than the outer shape of the second superabsorbent polymer particles 53 in order to prevent the second superabsorbent polymer particles 53 from falling off. In addition, when the material of the upper sheet 51 is hydrophobic, a hydrophilic agent can be contained therein.

The lower sheet 52 may be a liquid-permeable material or a liquid-impermeable material, and is not particularly limited, but is preferably a highly absorbent nonwoven fabric having a Klemm absorbency of 50 mm or more, a water retention capacity under load of 0.1 g or more, and a water retention capacity under no load of 0.5 g or more. As shown in FIG. 17(b), non-viscous liquid U such as urine supplied to the cell absorption sheet 50 is absorbed by the second highly absorbent polymer particles 53 in the cell absorption sheet 50, and non-viscous liquid U that reaches the lower sheet 52 without being absorbed by the second highly absorbent polymer particles 53 is absorbed by the lower sheet 52, retained in the lower sheet 52, and diffused, and then can be sucked up by the second highly absorbent polymer particles 53 in the cell absorption sheet 50. Here, the joints 54 of the cell absorption sheet 50 that do not have the second superabsorbent polymer particles 53 extend continuously toward the periphery of the cell absorption sheet 50, and when the back surface of the cell absorption sheet 50 has a protrusion 50p, the gap between the back surface of the cell absorption sheet 50 and the opposing surface also extends continuously toward the periphery of the cell absorption sheet 50. Therefore, if the water retention of the cell absorption sheet 50 is low, the non-viscous liquid U that has permeated the cell absorption sheet 50 moves on the liquid impermeable sheet 11 and seeps out from the periphery of the absorbent 70 toward the skin side, and may adhere to the skin or leak.

The Klemm absorbency of the highly absorbent nonwoven fabric constituting the lower sheet 52 is particularly preferably 70 mm or more. The upper limit of the Klemm absorbency of the highly absorbent nonwoven fabric constituting the lower sheet 52 is not particularly limited, but is preferably about 150 mm, and is particularly preferably 100 mm. The water retention capacity under load of the highly absorbent nonwoven fabric constituting the lower sheet 52 is particularly preferably 0.13 g or more. The upper limit of the water retention capacity under load of the highly absorbent nonwoven fabric constituting the lower sheet 52 is not particularly limited, but is preferably about 0.30 g, and is particularly preferably 0.26 g. The water retention capacity under no load of the highly absorbent nonwoven fabric constituting the lower sheet 52 is particularly preferably 0.70 g or more. The upper limit of the water retention capacity under no load of the highly absorbent nonwoven fabric constituting the lower sheet 52 is not particularly limited, but is preferably about 1.40 g, and is particularly preferably 1.20 g.

The highly absorbent nonwoven fabric constituting the lower sheet 52 is not limited by the material or manufacturing method, and the highly absorbent nonwoven fabric 42 similar to that of the upper auxiliary layer 71 can be suitably used. When the joint 54 between the upper sheet 51 and the lower sheet 52 is formed by welding, the highly absorbent nonwoven fabric constituting the lower sheet 52 is suitably made of heat-sealed fibers such as polyethylene fibers or composite fibers containing a polyethylene component. In particular, since the lower sheet 52 is intended to temporarily store non-viscous liquid U such as urine, it is preferable that the highly absorbent nonwoven fabric constituting the lower sheet 52 has a larger water retention capacity than the highly absorbent nonwoven fabric 42 of the upper auxiliary layer 71. For example, it is preferable that the highly absorbent nonwoven fabric constituting the lower sheet 52 has a water retention capacity under load that is 2 to 4 times that of the highly absorbent nonwoven fabric 42 of the upper auxiliary layer 71. More specifically, the basis weight of the highly absorbent nonwoven fabric that makes up the lower sheet 52 is 1.2 to 1.8 times the basis weight of the highly absorbent nonwoven fabric 42 that makes up the upper auxiliary layer 71, or the highly absorbent nonwoven fabric that makes up the lower sheet 52 can be multiple layers of highly absorbent nonwoven fabric that are equivalent to the highly absorbent nonwoven fabric used in the upper auxiliary layer 71.

When the upper sheet 51 has a recess 50c, the surface area of the upper sheet 51 is increased, and liquid can be supplied to a wider area of the highly absorbent polymer particles in the cell absorption sheet 50, which is preferable. On the other hand, when the lower sheet 52 has a recess 50c, the surface area of the lower sheet 52 is increased, and the water retention capacity of the lower sheet 52 is increased compared to when the lower sheet 52 is flat without being shaped, which is preferable.

The middle sheet 80 is not particularly limited as long as it is a nonwoven fabric, but the fineness of the constituent fibers of the nonwoven fabric is preferably about 1.6 to 7.0 dtex, and more preferably 5.6 to 6.6 dtex. The porosity of the nonwoven fabric of the middle sheet 80 is preferably 80 to 98%, and more preferably 90 to 95%. When the fineness and porosity of the middle sheet 80 are within this range, the elasticity of the middle sheet 80 is ensured as much as possible, and the second superabsorbent polymer particles 53 can easily enter the fiber gaps of the middle sheet 80 before and during the absorption of excreted liquid. Therefore, the fibers of the middle sheet 80 that spread within the recesses 50c during absorption ensure a liquid passage to each of the second superabsorbent polymer particles 53, so that even after the second superabsorbent polymer particles 53 start to expand, the decrease in diffusivity is suppressed, and gel blocking is less likely to occur. The thickness of the middle sheet 80 may be appropriately determined in consideration of the depth 50d of the recess 50c and the degree of penetration into the recess 50c, but the thickness is preferably 10% to 90% of the depth 50d of the recess 50c, and more preferably 70% to 90%. The basis weight of the middle sheet 80 may also be appropriately determined for the same reason, but within the above thickness range, it is preferable to set it to about 25 to 40 g/ ^m2 . In order to increase the porosity of the nonwoven fabric of the middle sheet 80 (widen the fiber gaps), it is preferable that the constituent fibers are crimped fibers. Furthermore, if the constituent fibers of the nonwoven fabric of the middle sheet 80 are hydrophilic fibers (including fibers that have been made hydrophilic by a hydrophilizing agent), the water retention will be high, and if they are hydrophobic fibers, the diffusibility will be improved. The fiber bonding method of the nonwoven fabric is not particularly limited, but in order to increase the porosity (widen the fiber gaps) while sufficiently bonding the fibers to ensure elasticity, an air-through nonwoven fabric in which the fibers are bonded by hot air heating is preferable for the middle sheet 80.

As long as the surface of the middle sheet 80 facing the recess 50c is inserted into the recess 50c, it is preferable that the surface contacts the inner surface of the recess 50c as shown in Figs. 13(a)(c) and 14(a)(c), respectively, but it may be spaced apart as shown in Fig. 13(b). When the surface of the middle sheet 80 facing the recess 50c is spaced apart from the inner surface of the recess 50c, the spaced apart distance 80s can be determined as appropriate, but is preferably 30% or less of the depth 50d of the recess 50c. In this way, when a gap occurs within the cell 55, the protrusion 50p (recess 50c) may be crushed in the product state according to the gap.

The middle sheet 80 may be adhered to at least one of the upper sheet 51 and the lower sheet 52 with hot melt adhesive 80h both within the cells 55 and at the joints 54, as shown in Figures 13(a)-(c) and 14(a), respectively, or may not be adhered to both the upper sheet 51 and the lower sheet 52, as shown in Figure 14(c).

It is preferable that the second superabsorbent polymer particles 53 are almost entirely (e.g., 95% or more) unfixed to the upper sheet 51, the lower sheet 52, and the middle sheet 80, and are freely movable. However, a part or almost entirely (e.g., 95% or more) of the second superabsorbent polymer particles 53 can be adhered or stuck to at least one of the upper sheet 51, the lower sheet 52, and the middle sheet 80. FIG. 14(b) shows an example in which a part of the second superabsorbent polymer particles 53 is adhered to the lower sheet 52 by an adhesive 53h such as a hot melt adhesive. The second superabsorbent polymer particles 53 may be agglomerated to some extent. In particular, when the second superabsorbent polymer particles 53 are freely movable within the cells 55, if the cells 55 have hollow portions, the second superabsorbent polymer particles 53 may move within the cells 55 during use, causing noise, or the second superabsorbent polymer particles 53 may be unevenly distributed within the cells 55, causing absorption inhibition. Therefore, in order to solve this problem, as described above, one preferred embodiment is to bring the surface of the middle sheet 80 facing the recess 50c into contact with the inner surface of the recess 50c, in other words, to fill almost the entire cell 55 including the recess 50c with the fibers of the middle sheet 80 with a high porosity. This makes it difficult for the second superabsorbent polymer particles 53 to move freely, since they are captured by the fibers of the middle sheet 80, or pressed against the upper sheet 51 or the lower sheet 52, or both. Therefore, while preventing the expansion of the second superabsorbent polymer particles 53 from being hindered, it is possible to prevent the generation of noise due to the movement of the second superabsorbent polymer particles 53 and the hindering of absorption due to the second superabsorbent polymer particles 53 being unevenly distributed in the cell 55.

13(a)(b) and 14(c), it is preferable that the second superabsorbent polymer particles 53 are present most abundantly on the upper surface of the middle sheet 80 and are present less abundantly downward from there, because the middle sheet 80 prevents the second superabsorbent polymer particles 53 from giving a rough feel (uncomfortable feeling) to the user's hand when the user touches the outer surface of the diaper with his/her hand. In particular, when the middle sheet 80 is a bulky nonwoven fabric with a high porosity, the second superabsorbent polymer particles 53 can enter the fiber gaps of the middle sheet 80 before and during the absorption of excreted liquid, which further improves the absorption rate. That is, in the early stages of absorption, absorption progresses on the upper surface of the middle sheet 80 where the second superabsorbent polymer particles 53 are distributed in large numbers, but the rate of absorption is limited. Therefore, in the initial stage of absorption, the excreted liquid penetrates into the middle sheet 80 where there are few second superabsorbent polymer particles 53, and is absorbed by the second superabsorbent polymer particles 53 in the middle sheet 80, or is temporarily stored until it is absorbed by the second superabsorbent polymer particles 53, or is diffused into the surrounding cells 55. The excreted liquid diffused to the surroundings is absorbed by the second superabsorbent polymer particles 53 in the middle sheet 80 present there, or is sucked up by the second superabsorbent polymer particles 53 present in large amounts above them. Then, in the process in which each second superabsorbent polymer particle 53 absorbs the excreted liquid, the superabsorbent polymer expands the fiber gaps and expands while penetrating between them or compressing the middle sheet 80. Due to this absorption mechanism, the excreted liquid is quickly diffused over a wide area of the cell absorption sheet 50 and is received inside the cell absorption sheet 50, which not only improves the absorption speed but also provides excellent backflow prevention. In order to effectively utilize this absorption mechanism, it is preferable that the recesses 50c are formed at least in the portions of the upper sheet 51 that form each cell 55.

The degree of distribution of the second superabsorbent polymer particles 53 within the cells 55 can be determined as appropriate, but in normal cases, the weight proportion of the second superabsorbent polymer particles 53 present on the upper surface of the middle sheet 80 is preferably 50% or more of the total, and the weight proportion of the superabsorbent polymer held within the middle sheet 80 (i.e., not on the lower sheet 52) is preferably 45% or more of the total.

Of course, the distribution of the second superabsorbent polymer particles 53 in the cells 55 is not limited to this. Therefore, if the absorption from the highly absorbent nonwoven fabric constituting the lower sheet 52 is important, it is also preferable to have the second superabsorbent polymer particles 53 present most abundantly on the upper surface of the lower sheet 52, as shown in FIG. 13(c), and to have a distribution that decreases from there toward the upper side. Also, as shown in FIG. 14(a), the amount of the second superabsorbent polymer particles 53 present on the upper surface of the middle sheet 80 and on the upper surface of the lower sheet 52 may be greater than the amount in between them. Furthermore, although not shown, the second superabsorbent polymer particles 53 may be present most abundantly in the middle of the thickness direction of the middle sheet 80, and to have a distribution that decreases from there toward the upper and lower sides. This form can be formed by making the middle sheet 80 a two-layer nonwoven fabric and sandwiching the second superabsorbent polymer particles 53 between the layers.

The basis weight of the second superabsorbent polymer particles 53 can be appropriately determined. In the absorbent 70 of this example, since the upper auxiliary layer 71 contains the first superabsorbent polymer particles 43, the basis weight of the second superabsorbent polymer particles 53 in the main absorbent layer 72 can be kept low, but it is not appropriate for the upper auxiliary layer 71 alone to absorb a relatively large amount of excreted liquid such as urine. Therefore, although it cannot be said in general, it is preferable that the basis weight of the second superabsorbent polymer particles 53 is higher than the basis weight of the first superabsorbent polymer particles 43, and can be, for example, 150 to 250 g/m ^2. In general, if the basis weight of the second superabsorbent polymer particles 53 is less than 150 g/m ² , it is difficult to ensure the absorption amount, and if it exceeds 250 g/m ² , the gritty feel (uncomfortable feeling) of the second superabsorbent polymer particles 53 is easily transmitted to the hand when the user touches the outer surface of the product with his/her hand.

The planar shape of the cells 55 can be determined as appropriate, and as shown in FIG. 8, can be a hexagon, rhombus, square, rectangle, circle, ellipse, etc., but a polygon is preferable for a denser arrangement, and it is preferable to arrange the cells without gaps as in the illustrated example. The cells 55 can be arranged with the same shape and size, or multiple types of cells 55 that differ in at least one of the shape and size (not shown) can be arranged in combination.

The planar arrangement of the cells 55 (i.e., the aggregates of the second superabsorbent polymer particles 53) can be appropriately determined, but a regularly repeated planar arrangement is preferable, and in addition to regularly repeated arrangements such as an oblique lattice as shown in FIG. 12(a), a hexagonal lattice as shown in FIG. 12(b) (also called a staggered arrangement), a square lattice as shown in FIG. 12(c), a rectangular lattice as shown in FIG. 12(d), a parallelepiped lattice (as shown in the figure, two groups of a large number of parallel diagonal rows are arranged so as to intersect with each other) as shown in FIG. 12(e) (including those inclined at an angle of less than 90 degrees with respect to the stretching direction), a regularly repeated group of cells 55 (the arrangement of the group units may be regular or irregular, and may be a pattern or letter-like, etc.) may also be used.

For example, the dimension 55L in the front-rear direction LD (equal to the dimension of the protrusion 50p in the front-rear direction LD) can be about 6 to 30 mm, and the dimension 55W in the width direction WD (equal to the dimension of the protrusion 50p in the width direction WD) can be about 7 to 50 mm. The area of each cell 55 can be about 31 to 1650 ^mm2 .

When ease of manufacture and manufacturing stability are important, it is desirable that the joint 54 joining the upper sheet 51 and the lower sheet 52 be formed in a uniform mesh pattern throughout. For this reason, as in the illustrated example, it is desirable to arrange one or more types of cells 55 of the same dimensions and planar shape regularly and without gaps. It is desirable that the joint 54 joining the upper sheet 51 and the lower sheet 52 be a welded part where the upper sheet 51 and the lower sheet 52 are welded together, such as by ultrasonic welding or heat sealing, but it may also be an adhesive part joined together via a hot melt adhesive.

The joints 54 of the upper sheet 51 and the lower sheet 52 are arranged to surround each cell 55, and as long as they are the boundaries between adjacent cells, they can be formed in a dotted line shape (intermittent in the direction surrounding each cell 55) as shown in the illustrated example, or in a continuous line shape. When the joints 54 are formed intermittently, it is preferable that there are no second superabsorbent polymer particles 53 between the joints 54 in the direction surrounding the cells 55, or that there are fewer second superabsorbent polymer particles 53 than within the cells 55. In particular, when the joints are provided in a dotted line shape (intermittent), the fiber group of the middle sheet extends between adjacent joints and between many cells. Therefore, a liquid diffusion passage is formed between adjacent joints, and the liquid diffusion between the cells is improved, thereby improving the absorption speed.

As shown in FIG. 10, the joints 54 may be weak joints 54b that can be peeled off by the expansion force of the second superabsorbent polymer particles 53 in the adjacent cells 55, or strong joints 54a that do not essentially peel off by the expansion force of the second superabsorbent polymer particles 53 in the adjacent cells 55. In order to accommodate expansion of the second superabsorbent polymer particles 53 that is equal to or greater than the volume of each cell 55, it is preferable that a part or all of the joints 54 are weak joints 54b. By having the weak joints 54b, adjacent cells 55 sandwiching the weak joints 54b can be peeled off and combined to form one large cell 55 by the absorption and expansion pressure of the second superabsorbent polymer particles 53 in the cells 55.

On the other hand, the strong joints 54a are parts that do not basically peel off even if the cells 55 on both sides absorb and expand, so that by continuing in a specific direction, it has the effect of improving diffusion, preventing the flow of the gelled material of the second superabsorbent polymer particles 53, and reducing the contact area on the surface side. Therefore, by combining this with weak joints, it is possible to construct a cell absorption sheet 50 with various characteristics as described below. Note that it is desirable to make the joints 54 located on the outermost side in the width direction WD strong joints 54a because if they peel off, the second superabsorbent polymer particles 53 or their gelled material may leak out to the side of the cell absorption sheet 50. From the same viewpoint, it is preferable to extend the upper sheet 51 and the lower sheet 52 to a certain extent outside the cell 55 formation area in the width direction WD, and to provide edge joints 54c to this extended portion for reinforcement.

The difference in bonding strength can be easily formed by changing the area of the bonding portion 54, but is not limited to this. For example, when the bonding portion 54 is formed with a hot melt adhesive, a method of using different types of hot melt adhesive depending on the location can also be adopted. In particular, when the bonding portion 54 is formed by welding the upper sheet 51 and the lower sheet 52, the weak bonding portion 54b can be formed simply by making the bonding portion 54 dotted and widening the dot interval 54D. However, since the bonding portion 54 is the part that forms the boundary between adjacent cells 55, if the dot interval 54D is too wide, there will be many gaps at the boundary between adjacent cells 55, and the second superabsorbent polymer particles 53 will be more likely to move. Therefore, if the dotted weak bonding portion 54b is formed by combining the width 54W of the bonding portion 54 and the width of the dot interval 54D, the weak bonding portion 54b will be easily peeled off despite the small gap.

The dimensions of the joint 54 joining the upper sheet 51 and the lower sheet 52 can be determined as appropriate. For example, the width 54W (the dimension in the direction perpendicular to the direction surrounding the cells 55, and equal to the spacing between the cells 55) can be about 1.0 to 1.8 mm. When the joint 54 is formed in a dotted line shape (intermittently in the direction surrounding the cells 55), it is preferable that the dimension 54L of the joint 54 in the direction surrounding the cells 55 is about 0.6 to 1.5 mm, and the point spacing 54D is about 0.8 to 3.0 mm. In particular, in the case of the strong joint 54a, it is preferable that the width 54W is about 1.3 to 1.8 mm, the dimension 54L of the joint 54 is about 1.0 to 1.5 mm, and the point spacing 54D is about 0.8 to 2.0 mm. In addition, in the case of the weak joint 54b, it is preferable that the width 54W is approximately 1.0 to 1.3 mm, the dimension 54L of the joint 54 is approximately 0.6 to 1.0 mm, and the point spacing 54D is approximately 1.5 to 3.0 mm.

In order to make the weakly bonded portions 54b peelable, the type and amount of the second superabsorbent polymer particles 53 arranged in each cell 55 can be determined so that the volume of the second superabsorbent polymer particles 53 in the cell 55 at saturation absorption is sufficiently larger than the volume of the cell 55 adjacent to the weakly bonded portion 54b. In addition, in order to make the strongly bonded portions 54a essentially non-peeling, the type and amount of the second superabsorbent polymer particles 53 arranged in each cell 55 can be determined so that the volume of the second superabsorbent polymer particles 53 contained in the cells 55 that can be combined at saturation absorption is smaller than the volume of the cells 55 that can be combined due to peeling of the weakly bonded portions 54b after they are combined.

The width of the joint 54 when the joint 54 is formed as a continuous line, and the width 54W when the joint 54 is formed as a dotted line, can be constant in the direction surrounding the cell 55, or can be changed. In addition, the shape of each joint 54 when the joint 54 is formed as a dotted line can be appropriately determined, and can be the same or can be different depending on the part. In particular, when the shape of each cell 55 is polygonal, it is preferable to provide the joint 54 at at least one of the middle position of each side and each vertex position. In addition, in the case of the strong joint 54a, it is preferable to provide it at each vertex position, but in the case of the weak joint 54b, it is preferable not to provide it at each vertex position, because the weak joint 54b is more likely to peel off and the cell 55 is more smoothly combined.

As shown in Figures 8 and 11, it is preferable that a vertical strong bond line 58, in which the strong bond portion 54a continues in the front-rear direction LD, and a diffusion improvement portion 57 consisting of low expansion cells 55s adjacent to both sides of the strong bond line 58 are provided in the middle region of the width direction WD of the cell absorption sheet 50. The low expansion cells 55s of this diffusion improvement portion 57 contain less second superabsorbent polymer particles 53 per unit area than the cells 55 adjacent to both sides of the diffusion improvement portion 57, and the bond portions 54 between the cells 55 adjacent to both sides of the diffusion improvement portion 57 are weak bond portions 54b. In this case, as shown in Figure 10, at the beginning of the absorption of excreted liquid, a wide groove with the diffusion improvement portion 57 as its bottom is formed due to the difference in the amount of expansion between the diffusion improvement portion 57 and its surrounding parts, and the groove promotes liquid diffusion. This state continues until the weak joints 54b between the low expansion cells 55s of the diffusion improvement section 57 and the cells 55 on both sides of them are released by the expansion force of the second superabsorbent polymer particles 53 in the cells 55 surrounding the diffusion improvement section 57, and since the strong joints 54a do not come off even after the weak joints 54b are released, the groove width narrows, but the groove with the strong joints 54a at the bottom remains and diffusion is maintained. In other words, the groove width is wide at the beginning of absorption when the diffusion of a large amount of excreted liquid is important, and thereafter, the low expansion cells 55s of the diffusion improvement section 57 also merge with the surrounding cells 55 to prevent problems such as gel blocking, but the groove remains due to the strong joints 54a, and the diffusion improvement effect is maintained.

The amount of second superabsorbent polymer particles 53 contained in the low expansion cells 55s is preferably 1/3 or less by weight of the amount contained in the adjacent cells 55, and it is particularly preferable that no second superabsorbent polymer particles 53 are contained.

In FIG. 11, the strong bonded portions 54a are represented by thick dotted lines, the other weak bonded portions 54b are represented by thin dotted lines, and the cells 55 containing the second superabsorbent polymer particles 53 (cells 55 excluding the low expansion cells 55s and the low content cells 56 described below) are marked with diagonal lines in FIG. 11.

The diffusion improvement portion 57 may be provided over the entire length of the cell absorption sheet 50 as shown in FIG. 8, or may be provided only in the middle portion in the front-to-back direction LD (particularly including the crotch area and extending to both the front and back of the crotch area) as shown in FIG. 11. The diffusion improvement portion 57 may be provided in one location in the center of the width direction WD as shown in FIG. 8 and FIG. 11, or may be provided in multiple locations spaced apart in the width direction WD (not shown).

If the cells 55 can be combined over the entire front-rear direction LD of the cell absorption sheet 50, the gelled second superabsorbent polymer particles 53 that expand during absorption can move significantly in the front-rear direction LD within the combined cells 55, and the gelled material may gather in low areas such as the crotch area, causing a poor fit. Therefore, as shown in FIG. 8, it is a preferred embodiment that multiple horizontal strong bond lines 59 (see FIG. 7), which are parts where the strong bond parts 54a continue continuously or intermittently (continuous lines or dotted lines) in the width direction WD or diagonally, are provided at intervals in the front-rear direction LD. This makes it possible to prevent the gelled second superabsorbent polymer particles 53 from moving in the front-rear direction LD by the strong bond parts 54a that do not basically peel off during absorption, and to prevent the cell absorption sheet 50 from losing its shape. Of course, as shown in FIG. 11, it is also possible to have a form that does not have such horizontal strong bond lines 59.

In particular, as shown in FIG. 8, when the vertical strong bond lines 58, which are the portions where the strong bond portions 54a continue in the front-rear direction LD over the entire length of the cell absorption sheet 50, are provided on both sides of the width direction WD along the side edges of the cells 55 located at the outermost sides in the width direction WD, and are also provided in the middle of these width direction WD, and the horizontal strong bond lines 59 are portions that continue in the width direction WD or in a diagonal direction so as to extend between the vertical strong bond lines 58 adjacent to each other in the width direction WD, the cells 55 do not merge beyond the maximum expansion section 55G surrounded by the strong bond portions 54a, so that the gelled material of the second superabsorbent polymer particles 53 that expands during absorption does not move outside the maximum expansion section 55G, and the shape of the cell absorption sheet 50 during absorption can be effectively prevented from collapsing. In addition, the vertical strong bond lines 58, which are the portions where the strong bond portions 54a continue in the front-rear direction LD, improve the vertical liquid diffusibility, and the horizontal strong bond lines 59, which are the portions where the strong bond portions 54a continue in the width direction WD or in a diagonal direction, improve the horizontal liquid diffusibility. For example, in the embodiment shown in FIG. 8, if urine is excreted at the position indicated by the symbol Z, as shown in FIG. 9, the urine will diffuse around that position, while being absorbed by the second superabsorbent polymer particles 53 at each position. At this time, as shown in FIG. 9 and FIG. 10, for cells 55 in which the expansion pressure of the second superabsorbent polymer particles 53 inside has increased, the weak bonds 54b around the cells 55 cannot resist the expansion pressure and peel off, and merge with adjacent cells 55. This merger continues as long as the absorption and expansion of the second superabsorbent polymer particles 53 can peel off the weak bonds 54b, and can progress to cells 55 with strong bonds 54a around them.

The size, shape and arrangement of the maximum expansion section 55G (i.e. the arrangement of the strong joints 54a) can be determined as appropriate, but if the maximum expansion section 55G is made too small, there will be no point in providing the strong joints 54a, and even if there are a large number of cells 55, if they are formed to be elongated, the shape of the cells 55 after they combine will be difficult to expand.

In the embodiment shown in Figures 8 to 10, the vertical strong bond lines 58 are provided at the center and both sides in the width direction WD of the cell absorption sheet 50, and the horizontal strong bond lines 59 are zigzag-shaped, extending in the front-rear direction while repeatedly bending left and right between the vertical strong bond lines 58 at the center and the vertical strong bond lines 58 at both sides. As a result, the maximum expansion section 55G, which is approximately triangular with an apex at the vertical strong bond line 58 at the center, and the maximum expansion section 55G, which is approximately triangular with an apex at the vertical strong bond lines 58 at both sides, are alternately formed in the front-rear direction. When the horizontal strong bond lines 59 are formed in a zigzag shape in this way, the horizontal liquid diffusion can be efficiently promoted with a small number of horizontal strong bond lines 59, and the maximum expansion section 55G becomes an approximately triangular shape that is easy to expand, and the cell volume increase amount relative to the number of cells 55 that are combined is excellent, which is preferable.

It is also possible to have only the vertical strong bond lines 58 without providing the low expansion cells 55s. In this case, the strong bond parts 54a do not come off when absorbing excretory liquid, so the grooves with the strong bond parts 54a as their bottoms remain, improving diffusion.

On the other hand, as shown in FIG. 8 and the like, low-content cells 56 in which the amount of second superabsorbent polymer particles 53 contained per unit area is less than that of other cells can be provided. In FIG. 11, the cells 55 containing the second superabsorbent polymer particles 53 (cells 55 excluding the low expansion cells 55s and the low content cells 56) are marked with diagonal lines. Of these, the area marked with diagonal lines in FIG. 8 is assumed to be the scattering area 53A of the second superabsorbent polymer particles 53 during manufacturing, so there are parts of the peripheral cells 55 without diagonal lines, but if the second superabsorbent polymer particles 53 are movable within the cells 55, the position of the second superabsorbent polymer particles 53 in the cells 55 is not fixed in the product, and the second superabsorbent polymer particles 53 can be distributed throughout the cells 55 as in the other figures. The amount of second superabsorbent polymer particles 53 contained in the low content cells 56 is preferably 1/2 or less of that in other cells by weight, and is particularly preferably not contained at all. For example, the front and rear ends of the cell absorption sheet 50 are formed by cutting into individual cell absorption sheets 50 during manufacturing, so if the second superabsorbent polymer particles 53 are present at these positions, there is a risk that the life of the blade of the cutting device will be shortened. Therefore, it is desirable that at least the cells 55 at the positions where the front and rear ends of the cell absorption sheet 50 pass through are low-content cells 56. In addition, by making the cells 55 on both sides in the middle of the front-to-rear direction LD of the cell absorption sheet 50 low-content cells 56, this portion will expand less even after absorption, and therefore the cell absorption sheet 50 will have a shape that fits around the legs even after absorption.

In the above example, only the second superabsorbent polymer particles 53 are contained within the cells 55, but it is also possible to contain powder particles other than superabsorbent polymer particles, such as deodorant particles, together with the second superabsorbent polymer particles 53.

(Easy-to-bend section)
It is preferable that both sides of the portion of the cell absorption sheet 50 located in the crotch area M are provided with easy-to-bend parts 90 that extend linearly along the leg circumference while crossing the joints 54 and the cells 55. If the easy-to-bend parts 90 are not provided, the diaper can be bent in any direction at any of the joints 54 of the uniformly provided net-like pattern, and therefore, while the diaper has excellent fit when worn, it may be deformed into an unintended shape. In contrast, as shown in Figs. 1 and 8, when the easy-to-bend parts 90 are provided, both sides of the portion of the cell absorption sheet 50 located in the crotch area M are easily bent to the front side along the easy-to-bend parts 90, not the joints 54 for forming the cells 55, as shown in Fig. 19. Therefore, when the present tape-type disposable diaper is worn and sandwiched between the legs, both sides of the crotch area M are easily deformed into a desired shape along the inner thighs of the wearer, and leakage and deterioration of the fit are less likely to occur.

By having the easy-to-fold portion 90, both sides of the portion of the cell absorption sheet 50 located in the crotch area M can be easily folded to the front side along the easy-to-fold portion 90, but having at least one of the flat gathers and rising gathers 60 described above is preferable because it ensures that the folding direction is toward the front side.

The planar shape of the easy-to-bend portion 90 is not particularly limited as long as it extends linearly around the leg. For example, the easy-to-bend portion 90 may have a shape having an innermost portion 91 whose tangent is a straight line along the front-to-back direction LD, and a front diagonal portion 92 and a rear diagonal portion 93 that extend from the innermost portion 91 to the front and rear sides so as to be located outside the width direction WD. In this case, the innermost portion 91 (i.e., a portion whose tangent is a straight line along the front-to-back direction LD) may be only one point, and the entire portion may be connected from the front diagonal portion 92 to the rear diagonal portion 93 without passing through a straight line portion, but as shown in the illustrated example, the innermost portion 91 may extend linearly along the front-to-back direction LD by 1/4 or more of the dimension of the entire easy-to-bend portion 90 in the front-to-back direction LD. The easy-to-bend portion 90 may be curved without a straight portion. The easy-to-bend portion 90 may have an inflection point in a plan view, but it is preferable that it does not have one (it is not zigzag-shaped). The easy-to-bend portion 90 may extend continuously or may extend intermittently (in a dotted line shape).

The dimension of the easily bendable portion 90 in the front-rear direction LD can be determined appropriately taking into consideration the standard dimensions of the wearer's crotch area M, and can usually be about 30 to 70% of the overall product length L. The dimension of the easily bendable portion 90 in the width direction WD (one side) can be determined appropriately taking into consideration the standard dimensions of the wearer's crotch area M and the overall width 50W of the cell absorption sheet 50, and can be, for example, about 10 to 30% of the overall width 50W of the cell absorption sheet 50. The line width 90W of the easily bendable portion 90 (the dimension indicated by the symbol 54W when the easily bendable portion 50 is formed in the same way as the joint, as described below) can be determined appropriately, but is usually preferably 1.5 to 12.0 mm.

The easy-to-bend portion 90 can be formed by subjecting the cell absorption sheet 50 to non-heated embossing or crease processing, or by perforation processing, or can be formed in the same manner as the joint portion 54 surrounding the cell 55 described above. In other words, the easy-to-bend portion 90 may be a portion in which the upper sheet 51 and the lower sheet 52 are welded while being pressed in the thickness direction and intermittently provided along the leg circumference. In this case, it is preferable to make the width of the welded portion in the easy-to-bend portion 90 (similar to 54W) wider than the width 54W of the joint portion 54 (e.g., 1.5 to 3.0 times) and to make the interval between the welded portions in the easy-to-bend portion (similar to 54D) narrower than the interval 54D of the joint portion 54 (e.g., 1/4 to 1/2 times), since this makes it easier to bend along the easy-to-bend portion 90 more reliably.

When the easy-to-bend portion 90 is formed by the welded portion of the upper sheet 51 and the lower sheet 52, it is preferable that the welded portion, like the strong joint portion 54a described above, does not peel off due to the expansion force of the superabsorbent polymer particles in the adjacent cells 55, because the effect of the easy-to-bend portion 90 is exerted even after the absorption of excrement. In addition to this or instead, as in the illustrated example, if the cell 55 through which the easy-to-bend portion 90 passes and the cell 55 located to the side of it are the low-content cells 56 described above, it is preferable because it is less likely that a situation will occur in which the portions on both sides of the easy-to-bend portion 90 expand and push against each other, thereby hindering bending along the easy-to-bend portion 90 (force acts in the direction of flattening).

In addition, as shown in FIG. 13(a) and other figures, if the upper sheet 51 of the cell absorption sheet 50 has a recess 50c recessed upward, when the highly absorbent polymer particles are absorbed and expanded, the portions on both sides of the easy-to-bend portion 90 expand and push against each other, which may hinder bending along the easy-to-bend portion 90 (a force acts in the direction of flattening). Therefore, taking this into consideration, as shown in FIG. 13(c), it is preferable that the portions of the lower sheet 52 located in each cell 55 are pushed downward to form a pair of recesses 50c and protrusions 50p on the upper and lower surfaces of the lower sheet 52, and that the portions of the upper sheet 51 located in each cell 55 are not pushed out in the thickness direction and are flat.

It is desirable that the cell absorption sheet 50 is joined to an adjacent member. However, if the portion of the cell absorption sheet 50 on the side of the easy-to-bend portion 90 is joined to an adjacent member, the resistance to bending along the easy-to-bend portion 90 will be large. Therefore, it is preferable that the portion of the cell absorption sheet 50 located between the left and right easy-to-bend portions 90 is joined to at least one of the adjacent members on the top or bottom, and the entire portion on the side of the easy-to-bend portion 90 is not joined to the adjacent members on the top, bottom, or sides, so that the bending action along the easy-to-bend portion 90 described above can be easily exerted.

The easy-to-fold section 90 may be provided on at least one of the members on the outer side of the cell absorption sheet 50, such as the packaging sheet 45, intermediate sheet 40, and top sheet 30 in the illustrated example, but it is preferable that it is not provided on at least the top sheet 30 and intermediate sheet 40, and it is more preferable that it is not provided on any of the members on the outer side of the cell absorption sheet 50.

(Superabsorbent polymer particles)
The first superabsorbent polymer particles 43 and the second superabsorbent polymer particles 53 can be used as they are for this type of absorbent article. The particle size of the first superabsorbent polymer particles 43 and the second superabsorbent polymer particles 53 is not particularly limited, but it is preferable that, for example, the ratio of particles larger than 500 μm is 30% by weight or less, the ratio of particles smaller than 500 μm and larger than 180 μm is 60% by weight or more, the ratio of particles larger than 106 μm and smaller than 180 μm is 10% by weight or less, and the ratio of particles smaller than 106 μm is 10% by weight or less. The measurement of these particle sizes is performed as follows. That is, 500 μm, 180 μm, and 106 μm standard sieves (JIS Z8801-1:2006) and a receiving tray are arranged in this order from the top, 10 g of a sample of superabsorbent polymer particles is put into the top 500 μm sieve, and after sieving (shaking for 5 minutes), the weight of the particles remaining on each sieve is measured. As a result of this sieving, the weight ratios of the sample remaining on each of the 500 μm, 180 μm, and 106 μm sieves and the sample remaining on the receiving tray to the put-in amount are respectively the ratio of particles over 500 μm, the ratio of particles 500 μm or less and over 180 μm, the ratio of particles over 106 μm and 180 μm or less, and the ratio of particles 106 μm or less.

The first and second superabsorbent polymer particles 43 and 53 can be used without any particular limitations, but those with a water absorption of 40 g/g or more are preferred. In addition, it is preferred that the first and second superabsorbent polymer particles 43 and 53 are manufactured by a crushing method, since gel blocking is less likely to occur. The first and second superabsorbent polymer particles 43 and 53 can be starch-based, cellulose-based, or synthetic polymer-based, and can be starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, crosslinked products of sodium carboxymethylcellulose, or acrylic acid (salt) polymers. The first and second superabsorbent polymer particles 43 and 53 can be preferably in the form of powder or granules that are commonly used, but other shapes can also be used.

The first and second superabsorbent polymer particles 43 and 53 preferably have a water absorption speed of 70 seconds or less, and particularly 40 seconds or less. If the water absorption speed is too slow, the liquid supplied to the absorbent body 70 tends to flow back out of the absorbent body 70, which is known as backflow.

The first and second superabsorbent polymer particles 43 and 53 preferably have a gel strength of 1000 Pa or more. This effectively prevents the sticky feeling that occurs after absorbing liquid.

(packaging sheet)
As shown in Fig. 3 and Fig. 16(a), the absorbent 70 can be wrapped with a wrapping sheet 45. In this case, one wrapping sheet 45 can be wrapped around the front and back surfaces and both sides of the absorbent 70 in a cylindrical shape, or two wrapping sheets 45 can be used to sandwich the absorbent 70 from both sides. As the wrapping sheet 45, tissue paper, especially crepe paper, nonwoven fabric, polylaminated nonwoven fabric, perforated sheet, etc. can be used. However, it is preferable that the sheet does not allow the superabsorbent polymer particles 53 to escape. When nonwoven fabric is used for the wrapping sheet 45, hydrophilic SMS nonwoven fabric (SMS, SSMMS, etc.) is particularly suitable, and polypropylene, polyethylene/polypropylene composite material, etc. can be used as the material. The basis weight of the nonwoven fabric used for the wrapping sheet 45 is preferably 5 to 40 g/m ² , especially 10 to 30 g/m ² .

As shown in FIG. 16(b), it is preferable to wrap the packaging sheet 45 from the back surface of the absorbent 70 through both sides in the width direction WD of the absorbent 70 to both sides of the upper surface of the absorbent 70, provide an area 45S not covered by the packaging sheet 45 in the middle of the width direction WD of the upper surface of the absorbent 70, and provide an upper auxiliary layer 71 so as to include the entire area 45S. The absorbent 70 is generally covered with the packaging sheet 45 to prevent leakage of superabsorbent polymer particles during manufacture, before use, or after absorption, but in the case of the absorbent 70 having the above-mentioned upper auxiliary layer 71, it is preferable that the upper auxiliary layer 71 quickly contacts the viscous liquid N. Therefore, as shown in FIG. 16(b), it is preferable to limit the coverage area of the packaging sheet 45 and expose the upper auxiliary layer 71 to the upper surface of the absorbent 70. Even with this structure, the parts of the absorbent 70 that are not covered by the packaging sheet 45 are covered by the highly absorbent nonwoven fabric 42 of the upper auxiliary layer 71, and the upper auxiliary layer 71 is based on highly absorbent nonwoven fabric 42 that has a high Klemm absorbency (i.e., is dense), so it has almost the same effect of preventing leakage of the highly absorbent polymer particles as if the entire absorbent 70 were covered with the packaging sheet 45.

<Explanation of terms used in the specification>
When used in this specification, the following terms have the following meanings, unless otherwise stated in the specification.

"MD direction" and "CD direction" refer to the flow direction (MD direction) in the manufacturing equipment and the horizontal direction (CD direction) perpendicular to it, one of which is the front-to-back direction of the product, and the other is the width direction of the product. The MD direction of a nonwoven fabric is the direction of fiber orientation of the nonwoven fabric. Fiber orientation is the direction in which the fibers of the nonwoven fabric are aligned, and can be determined, for example, by a measurement method based on the fiber orientation test method using zero-distance tensile strength in TAPPI standard method T481, or a simplified measurement method that determines the fiber orientation direction from the tensile strength ratio in the front-to-back direction and the width direction.

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

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

- "Front side" means the side of the component that is closest to the wearer's skin when worn, and "back side" means the side that is away from the wearer's skin when worn.

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

"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.

"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, and is used at a temperature of 37 degrees unless otherwise specified.

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

"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%. Using a sample collection template (100mm x 100mm), cut out a sample measuring 100mm x 100mm from the test piece that has reached a constant weight. Measure the weight of the sample and multiply it by 100 to calculate the weight per square meter, which is the basis weight.

The "thickness" is automatically measured using an automatic thickness measuring device (KES-G5 handy compression tester) under the conditions of a load of 0.098 N/cm ² and a pressurized area of 2 cm ² .

"Porosity" is measured by the following method. Specifically, a rectangular sample is cut from the inner sheet except for the joints. The length, width, thickness, and weight of the sample are measured. Using the raw material density of the nonwoven fabric, a hypothetical weight is calculated for a sample with the same volume but void ratio of 0%. The sample weight and hypothetical weight are substituted into the following formula to determine the void ratio.
Porosity = [(Virtual weight - Sample weight) / Virtual weight] x 100

"Water absorption" is measured according to JIS K7223-1996 "Test method for water absorption of superabsorbent resins."

"Water absorption rate" refers to the "time to the end point" when 2 g of superabsorbent polymer and 50 g of physiological saline are used to perform the JIS K7224-1996 "Water absorption rate test method for superabsorbent polymers."

"Klemm water absorbency" means the Klemm water absorbency measured according to "Paper and paperboard - Water absorption test method - Klemm method" specified in JIS P 8141:2004.

"Water retention" means a value measured by the following method. A test piece of 10 cm in MD x 10 cm in CD (area ¹⁰⁰ cm2) is prepared, and the weight before absorption is measured. Next, the test piece is immersed in artificial urine for 5 seconds, and then one corner is lightly pinched with the thumb and index finger (lightly pinched so as not to squeeze out as much water as possible), and the opposite corner is hung up so that it faces downward, and left for 30 seconds to allow the drops to fall. Thereafter, when measuring "water retention under load", the test piece is placed on eight sheets of filter paper (length 150 mm x width 150 mm) laid one on top of the other, and a square pillar-shaped weight (weight 3 kg) with a bottom surface of length 100 mm x width 100 mm is placed on the test piece so that the load is applied to the entire upper surface of the test piece, and the weight is removed after 5 minutes, and the weight of the test piece after absorption is measured. When measuring the "water retention under no load", the test piece is placed on eight layers of filter paper, and after five minutes, the weight of the test piece after absorption is measured without placing anything on top of it. Based on these measurement results, the difference between the weight after absorption and the weight before absorption is converted per ¹⁰ cm2 of area, and this is the "water retention under load" and "water retention under no load".

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

If no specification is given regarding the environmental conditions for a test or measurement, the test or measurement shall be performed 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%).

The present invention can be used for all absorbent articles, including tape-type disposable diapers such as the above example, pants-type disposable diapers, pad-type disposable diapers, sanitary napkins, etc.

LD...front-rear direction, M...crotch area, N...viscous liquid, U...non-viscous liquid, WD...width direction, 11...liquid-impermeable sheet, 12...exterior nonwoven fabric, 12T...target sheet, 13...fastening tape, 13A...locking portion, 13B...tape body, 13C...tape attachment portion, 30...top sheet, 40...middle sheet, 42...highly absorbent nonwoven fabric, 42a...pulp layer, 42b...support layer, 43...first highly absorbent polymer particles, 45...packaging sheet, 50...cell absorbent sheet, 50c...recess, 50d...depth , 50p...protruding portion, 51...upper sheet, 52...lower sheet, 53...second superabsorbent polymer particles, 54...joint, 54a...strong joint, 54b...weak joint, 54c...edge joint, 55...cell, 55G...most expanded section, 55s...low expansion cell, 56...low content cell, 57...diffusibility improvement section, 58...longitudinal strong joint line, 59...horizontal strong joint line, 60...rising gather, 62...gathered sheet, 70...absorbent body, 71...upper auxiliary layer, 72...main absorbent layer, 80...middle sheet, 90...easy-to-fold section.

Claims (4)

A crotch portion is located midway in the front-rear direction,
The device comprises an absorbent body, a liquid-permeable top sheet disposed on the front side of the absorbent body, and a liquid-impermeable sheet disposed on the back side of the absorbent body,
The absorbent body includes a cellular absorbent sheet having upper and lower sheets each having liquid permeability, cells which are portions of the upper and lower sheets that are not joined and are surrounded by the joints of the upper and lower sheets, and powder particles containing superabsorbent polymer particles contained in the cells;
The cell absorption sheet extends across both the front and rear sides of the crotch area,
the cell absorbent sheet has a uniform mesh pattern across the cell absorbent sheet;
The cell absorption sheet has on both sides of a portion located in the crotch area an easily bendable portion that extends linearly along the leg circumference while crossing the joint portion and the cell,
The upper sheet and the lower sheet are each made of a nonwoven fabric,
the joints are provided intermittently in a circumferential direction of the cell, and are formed by welding the upper sheet and the lower sheet while applying pressure in a thickness direction,
the easy-to-bend portion is a portion in which a welded portion formed by welding the upper sheet and the lower sheet while pressing them in a thickness direction is intermittently provided along the leg periphery,
The width of the welded portion in the easy-to-bend portion is wider than the width of the joint portion, and the interval between the welded portions in the easy-to-bend portion is narrower than the interval between the joint portions.
An absorbent article comprising : A crotch portion is located midway in the front-rear direction,
The device comprises an absorbent body, a liquid-permeable top sheet disposed on the front side of the absorbent body, and a liquid-impermeable sheet disposed on the back side of the absorbent body,
The absorbent body includes a cellular absorbent sheet having upper and lower sheets each having liquid permeability, cells which are portions of the upper and lower sheets that are not joined and are surrounded by the joints of the upper and lower sheets, and powder particles containing superabsorbent polymer particles contained in the cells;
The cell absorption sheet extends across both the front and rear sides of the crotch area,
the cell absorbent sheet has a uniform mesh pattern across the cell absorbent sheet;
The cell absorption sheet has on both sides of a portion located in the crotch area an easily bendable portion that extends linearly along the leg circumference while crossing the joint portion and the cell,
the easy-to-bend portion is a portion in which a welded portion formed by welding the upper sheet and the lower sheet while pressing them in a thickness direction is intermittently provided along the leg periphery,
the welded portion of the easily bendable portion is not peeled off due to the expansion force of the highly absorbent polymer particles in the adjacent cells;
The cell through which the easy-to-bend portion passes and the cells located to the side of the easy-to-bend portion do not contain superabsorbent polymer particles or are low-content cells having a lower content of superabsorbent polymer particles than adjacent cells on the inner side in the width direction of the cell.
An absorbent article comprising : A crotch portion is located midway in the front-rear direction,
The device comprises an absorbent body, a liquid-permeable top sheet disposed on the front side of the absorbent body, and a liquid-impermeable sheet disposed on the back side of the absorbent body,
The absorbent body includes a cellular absorbent sheet having upper and lower sheets each having liquid permeability, cells which are portions of the upper and lower sheets that are not joined and are surrounded by the joints of the upper and lower sheets, and powder particles containing superabsorbent polymer particles contained in the cells;
The cell absorption sheet extends across both the front and rear sides of the crotch area,
the cell absorbent sheet has a uniform mesh pattern across the cell absorbent sheet;
The cell absorption sheet has easy-to-bend portions on both sides of the portion located in the crotch area, the easy-to-bend portions extending linearly along the leg circumference while crossing the joints and the cells,
The cell absorption sheet is not joined to any of the upper, lower, or laterally adjacent members at any of the entire portions of the cell absorption sheet that are located to the side of the easy-to-fold portion.
An absorbent article comprising : The cell absorption sheet has a constant width throughout the front-to-rear direction.
The absorbent article according to any one of claims 1 to 4 .

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