JP7291053B2 - absorbent article - Google Patents

Description

The present invention relates to absorbent articles with improved absorbent performance.

The absorbent article includes 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 is absorbed and held by the absorber. As the absorber, a cotton-like fiber obtained by mixing superabsorbent polymer particles (SAP) with hydrophilic short fibers such as pulverized pulp is widely used. In order to meet the demands for further thinning, weight reduction, and cost reduction, a large number of cells surrounded by a liquid-permeable joint between an upper sheet and a lower sheet and in which the upper sheet and the lower sheet are not joined are provided. Various absorption sheets (hereinafter also referred to as cell absorption sheets) having (small chambers) and granules containing superabsorbent polymer particles contained in the cells have been proposed (for example, Patent Documents 1 to 6 below). reference).

However, since the absorption performance of the cell absorption sheet depends on the superabsorbent polymer particles, it is suitable for absorption of a large amount of non-viscous liquid such as urine, but its absorption speed is slow. Therefore, when the object to be absorbed is muddy stool, watery stool, or viscous liquid such as liquid in soft stool, the viscous liquid remains on the surface of the diaper for a certain length of time, flows and moves on the surface of the absorbent article, and spreads around the diaper. There was a problem that it was easy to leak from.

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

Therefore, a main object of the present invention is to improve absorbability of viscous liquids.

The absorbent article that solves the above problems is as follows.
<First Aspect>
comprising an absorbent body and a liquid-permeable top sheet disposed on the front side of the absorbent body,
The absorbent body includes a liquid-permeable upper sheet and a lower sheet, a cell surrounded by a joint portion of the upper sheet and the lower sheet, and a portion in which the upper sheet and the lower sheet are not joined, and a cell absorbent sheet having a granular material containing superabsorbent polymer particles housed in
The upper sheet is a highly absorbent nonwoven fabric having a Klemm water absorbency of 100 mm or more.
An absorbent article characterized by:

(Effect)
Improving the permeability of the viscous liquid in the layer covering the front side of the absorber is a conventional general approach, and it remains important, but rapid permeation of the viscous liquid by the absorber is It is facilitated by strong inhalation. That is, the initial absorption rate at the top of the absorbent body is extremely important for absorption of viscous liquids. The present absorbent article is based on such findings. The present absorbent article is characterized by using a material specialized for absorbing viscous liquid for the upper sheet of the cell absorbent body. That is, the upper sheet is a highly absorbent nonwoven fabric having a Klemm water absorbency of 100 mm or more, and can rapidly absorb and diffuse even a viscous liquid. Therefore, the absorbability of viscous liquids can be significantly improved. Also, the viscous liquid absorbed and diffused by the upper sheet can be delivered to the superabsorbent polymer particles in the cell absorbent sheet, and can be absorbed and retained by the superabsorbent polymer particles.

<Second Aspect>
The superabsorbent nonwoven fabric forming the upper sheet is a wet-laid nonwoven fabric containing 50% or more of pulp fiber or rayon fiber and having a basis weight of 25 to 50 g/m ² ,
The absorbent article of the first aspect.

(Effect)
The use of such a wet-laid nonwoven fabric is preferable because it can quickly absorb and diffuse a non-viscous liquid due to capillary action caused by minute interstices between fibers. In addition, such a wet-laid nonwoven fabric not only has a high Kremm water absorbency, but is also very thin and flexible, so that the decrease in flexibility and increase in thickness of the cell absorbent sheet as a whole can be suppressed.

<Third Aspect>
The wet-laid nonwoven fabric has a support layer containing synthetic resin long fibers and a pulp layer located on the outermost side and made only of pulp fibers.
The absorbent article of the second aspect.

(Effect)
Such a wet-laid nonwoven fabric is preferable because it can increase the strength due to the existence of the support layer while increasing the water retentivity of the upper side of the lower sheet due to the pulp layer.

<Fourth Aspect>
the cellular absorbent sheet comprises superabsorbent polymer particles adjacent to the back surface of the top sheet;
The absorbent article according to any one of the first to third aspects.

(Effect)
It is preferable that the cell-absorbent sheet has superabsorbent polymer particles adjacent to the back surface of the upper sheet, since the viscous liquid absorbed and diffused by the upper sheet can be efficiently delivered to the superabsorbent polymer particles.

<Fifth Aspect>
A pair of concave and convex portions are formed on the upper surface and the lower surface of the upper sheet by pushing upward the portion of the upper sheet located in each cell.
The absorbent article according to any one of the first to fourth aspects.

(Effect)
In the cell-absorbent sheet, at least one of the upper sheet and the lower sheet has recesses in which the portions located in the respective cells are pushed outward in the thickness direction in order to secure the volume when the superabsorbent polymer particles inside are expanded by absorption. It is preferable to have Here, if the upper sheet has recesses, the surface area of the upper sheet is increased, and the liquid can be supplied to the superabsorbent polymer particles in the cell absorbent sheet over a wider range, which is preferable.

<Sixth Aspect>
A liquid-impermeable sheet arranged on the back side of the absorber,
The lower sheet is a highly absorbent nonwoven fabric having a Klemm water 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.
The absorbent article according to any one of the first to fifth aspects.

(Effect)
As mentioned above, since the absorption speed of the cell-absorbing sheet is slow, the non-viscous liquid that has permeated the cell-absorbing sheet moves on the liquid-impermeable sheet, seeps out from the surroundings of the cell-absorbing sheet to the skin side, and adheres to the skin. It may stick or leak. In contrast, in the present absorbent article, of the non-viscous liquid supplied to the cell absorbent sheet, the non-viscous liquid that reaches the lower sheet without being absorbed by the superabsorbent polymer particles is absorbed by the lower sheet and After being retained and diffused within the sheet, it can be wicked up by the superabsorbent polymer particles within the cell absorbent sheet. Therefore, the non-viscous liquid that permeates the cell-absorbing sheet moves on the liquid-impermeable sheet, seeps out from the periphery of the cell-absorbing sheet to the skin side, and adheres to the skin or leaks. can. As a result, it is possible to achieve both absorbability for viscous liquids and absorbability for non-viscous liquids.

<Seventh Aspect>
A pair of concave and convex portions are formed on the upper surface and the lower surface of the lower sheet by pushing out the portion of the lower sheet located in each cell.
The absorbent article of the sixth aspect.

(Effect)
If the bottom sheet has recesses, the surface area of the bottom sheet is increased, and the water retention capacity of the bottom sheet is increased compared to the case where the bottom sheet is flat without being shaped, which is preferable.

According to the present invention, advantages such as improved absorption of viscous liquids are provided.

Fig. 2 is a plan view showing the inner surface of the tape-type disposable diaper when the diaper is unfolded; Fig. 2 is a plan view showing the outer surface of the tape-type disposable diaper when the diaper is unfolded; FIG. 6 is a sectional view taken along line 6-6 in FIG. 1; 7 is a cross-sectional view taken along line 7-7 in FIG. 1; FIG. (a) 8-8 cross-sectional view of FIG. 1, (b) 9-9 cross-sectional view of FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 1; FIG. (a) A broken bottom view of the main part of the absorber, (b) a cross-sectional view of 1-1. It is a top view of an absorber. It is a top view of an absorber. FIG. 10 is a cross-sectional view taken along line 2-2 of FIGS. 8 and 9; FIG. 2 is a plan view of an absorbent body showing a simplified joint portion; 4A and 4B are schematic plan views showing various arrangement examples of cells; FIG. Fig. 2 is a cross-sectional view of various cell absorbent sheets; Fig. 2 is a cross-sectional view of various cell absorbent sheets; FIG. 2 is a cross-sectional view showing layer structures of an absorbent body and a packaging sheet; FIG. 4 is a cross-sectional view showing changes during absorption; 1 is a cross-sectional view schematically showing the layer structure of a highly absorbent nonwoven fabric; FIG.

A tape-type disposable diaper will be described below as an example of an absorbent article with reference to the accompanying drawings. 1 to 6 show an example of a tape-type disposable diaper, where X in the figures indicates the total width of the diaper excluding the fastening tape, and L indicates the total length of the diaper. In addition, each structural member adjacent to each other in the thickness direction is fixed or joined in the same manner as a known diaper as necessary, except for the fixed or joined portions described below. A dotted pattern portion in the cross-sectional view indicates an adhesive such as a hot-melt adhesive as the fixing or joining means. The hot-melt adhesive can be applied by slot coating, continuous-line or dotted-line bead coating, spiral-shaped, Z-shaped, wavy-shaped spray coating, or pattern coating (transfer of hot-melt adhesive by letterpress method). can be applied by any method. Alternatively or additionally, at the fixing portion of the elastic member, a hot melt adhesive can be applied to the outer peripheral surface of the elastic member to fix the elastic member to the adjacent member. Hot-melt adhesives include, for example, EVA-based, adhesive rubber-based (elastomer-based), olefin-based, and polyester-polyamide-based adhesives, and can be used without particular limitation. As a fixing or joining means for joining each constituent member, a material welding means such as heat sealing or ultrasonic sealing can be used. In portions where liquid permeability in the thickness direction is required, adjacent components in the thickness direction are fixed or joined in an intermittent pattern. For example, when such intermittent fixing or bonding is performed with a hot-melt adhesive, intermittent pattern coating such as spiral, Z-shaped, and wavy patterns can be preferably used, and the range of coating width by one nozzle or more can be preferably used. In the case of coating, intermittent pattern coating such as spiral, Z-shape, wave-like, etc. can be performed with or without spacing in the width direction.

This tape-type disposable diaper has a basic structure in which an absorbent body 70 is interposed between a liquid-permeable top sheet and a liquid-impermeable sheet located on the back side. In addition, this tape-type disposable diaper has end flaps EF, which are portions extending to the front side and the rear side of the absorbent body 70 and do not have the absorbent body 70, and the side edges of the absorbent body 70. It has a pair of side flaps SF extending laterally. Both side edges of the side flaps SF are constricted along the circumference of the leg, but they may be straight. Fastening tapes 13 are provided on the side flaps SF of the dorsal portion B, respectively. , the fastening tape 13 is locked in place on the outer surface of the ventral portion F.

Moreover, in this tape-type disposable diaper, the entire outer surface other than the fastening tape 13 is formed of the exterior nonwoven fabric 12 . In particular, in the region including the absorbent body 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 liquid-impermeable sheet 11 has an absorbent material on the inner surface side. A body 70, an intermediate sheet 40 and a top sheet 30 are laminated in this order. The top sheet 30 and the liquid-impermeable sheet 11 are rectangular in the illustrated example, and have dimensions slightly larger than the absorbent body 70 in the front-rear direction LD and the width direction WD. The protruding peripheral edge portion and the peripheral edge portion of the liquid-impermeable sheet 11 protruding from the side edge of the absorber 70 are joined with a hot-melt adhesive or the like. Also, the liquid-impermeable sheet 11 is formed slightly wider than the top sheet 30 .

Furthermore, on both sides of the absorbent main body 10 , there are provided sit-up gathers 60 that stand up on the wearer's skin side. It is fixed to the range up to the inner surface of the side flap SF.

The details of each part will be described in order below. In addition, as the nonwoven fabric in the following description, a known nonwoven fabric can be appropriately used depending on the site and purpose. Constituent fibers of non-woven fabrics include, for example, synthetic fibers such as olefin-based, polyester-based, and polyamide-based fibers such as polyethylene or polypropylene (including composite fibers such as core-sheath fibers in addition to single-component fibers), as well as recycled rayon and cupra. Fibers, natural fibers such as cotton, etc., can be selected without particular limitation, and these can also be mixed and used. In order to increase the softness of the nonwoven fabric, it is preferable to use crimped fibers as the constituent fibers. In addition, even if the constituent fibers of the nonwoven fabric are hydrophilic fibers (including fibers made hydrophilic by a hydrophilic agent), they are hydrophobic fibers or water-repellent fibers (including fibers made water-repellent by a water-repellent agent). ). In addition, nonwoven fabrics are generally classified into short fiber nonwoven fabrics, long fiber nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, thermal bonded (air-through) nonwoven fabrics, and needle punched nonwoven fabrics, depending on the fiber length, sheet forming method, fiber bonding method, and laminate structure. Nonwoven fabrics are classified into nonwoven fabrics, point-bonded nonwoven fabrics, laminated nonwoven fabrics (such as SMS nonwoven fabrics and SMMS nonwoven fabrics in which a meltblown layer is sandwiched between spunbond layers), and any of these nonwoven fabrics can be used.

(exterior non-woven 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 touch. The fiber basis weight of the covering nonwoven fabric is preferably 10 to 50 g/m ² , particularly 15 to 30 g/m ² . The exterior nonwoven fabric 12 can be omitted, in which case the liquid-impermeable sheet 11 can have 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. (In this case, the waterproof film and the nonwoven fabric constitute a liquid-impermeable sheet.). Of course, in addition to these materials, liquid-impermeable and moisture-permeable materials, which have been favorably used in recent years from the viewpoint of preventing stuffiness, can also be exemplified. The liquid-impermeable and moisture-permeable material sheet is formed by, for example, kneading an inorganic filler into an olefin resin such as polyethylene or polypropylene, molding the sheet, and then stretching it in a uniaxial or biaxial direction. can be exemplified by the microporous sheet obtained by In addition, non-woven fabrics using microdenier fibers, leakproofness enhanced by applying heat and pressure to reduce the voids in the fibers, and methods such as coating with superabsorbent resins or hydrophobic resins and water repellents are used to improve waterproofing. A liquid-impermeable sheet without using a film can also be used as the liquid-impermeable sheet 11 .

(top sheet)
The top sheet 30 has the property of being permeable to liquid, and examples thereof include perforated or non-perforated nonwoven fabrics and porous plastic sheets. Both side portions of the top sheet 30 may be folded back to the back side of the absorbent body 70, or may protrude laterally beyond the side edges of the absorbent body 70 without being folded back as shown in the illustrated example.

The top sheet 30 can be fixed to a member adjacent to the back side by means of material welding, such as heat sealing or ultrasonic sealing, or hot-melt adhesive for the purpose of preventing misalignment with respect to the member on the back side. desirable. In the illustrated example, the top sheet 30 is fixed to the surface of the intermediate sheet 40 and the surface of the portion of the packaging sheet 45 located on the front side of the absorbent body 70 with a hot-melt adhesive applied to its back surface.

(intermediate sheet)
The intermediate sheet 40 is joined to the back surface of the top sheet 30 in order to quickly move the excreted liquid that has permeated the top sheet 30 to the absorbent body 70 side and to prevent reversion. For joining between the intermediate sheet 40 and the top sheet 30, besides using a hot melt adhesive, heat embossing or ultrasonic welding can also be used.

As the intermediate sheet 40, in addition to using a nonwoven fabric, a resin film having a large number of through holes can also be used. As the non-woven fabric, the same material as that of the top sheet 30 can be used. It is preferable because it is excellent. For example, an air-through nonwoven fabric can be suitably used as the intermediate sheet 40 . Composite fibers having a core-sheath structure are preferably used for the air-through nonwoven fabric. In this case, the resin used for the core may be polypropylene (PP), but polyester (PET) having high rigidity is preferable. The basis weight is preferably 17-80 g/m ² , more preferably 25-60 g/m ² . The thickness of the raw fibers of the nonwoven fabric is preferably 2.0 to 10 dtex. In order to make the non-woven fabric bulky, it is also preferable to use eccentric fibers, hollow fibers, or eccentric and hollow fibers whose core is not in the center as mixed fibers of all or part of the raw material fibers.

The intermediate sheet 40 in the illustrated example is shorter than the width of the absorbent body 70 and arranged in the center, but it may be provided over the entire width. The dimension of the intermediate sheet 40 in the front-rear direction LD may be the same as the full length of the diaper, the same as the dimension of the absorbent body 70, or within a short length range around the liquid-receiving area.

(Getting up gathers)
In order to prevent lateral movement of excrement on the top sheet 30 and prevent lateral leakage, it is preferable to provide rise gathers 60 protruding (raising) from the inner surface of both sides of the product in the width direction WD.

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

The inner surface of the gather sheet 62 has a fixing start end on the side of the top sheet 30 in the width direction WD, and the portion outside the fixing start end in the width direction WD is the side portion of the liquid-impermeable sheet 11 and the relevant portion. The outer nonwoven fabric 12 is fixed to the side portion of the exterior nonwoven fabric 12 located at the position with a hot-melt adhesive or the like.

Around the leg, the inner side in the width direction WD from the fixing start end of the rising gather 60 is fixed on the top sheet 30 at both ends in the product front-back direction LD, but the portion in between is a non-fixed free portion, This free portion is erected by the contractile force of the elastic member 63 . When the diaper is put on, the diaper is put on the body in a boat shape and the contractile force of the elastic member 63 acts, so that the contractile force of the elastic member 63 causes the rising gathers 60 to stand up and closely fit around the legs. As a result, so-called side leakage from around the leg is prevented.

Unlike the illustrated example, both ends in the front-rear direction LD of the inner portion of the gather sheet 62 in the width direction WD are divided into a base end portion extending inward from the outer portion in the width direction WD, and a base end portion of the base end portion. It is fixed in a double-folded state having a front end portion extending outward in the width direction WD by folding back from the edge on the center side in the width direction WD to the body side, and the portion therebetween is an unfixed free portion. can also

(flat gather)
Each side flap SF has, as shown in FIGS. A leg elastic member 64 made of an elongated elastic member such as thread rubber is fixed in a stretched state along the front-rear direction LD. ing. The leg elastic members 64 can also be arranged between the liquid-impermeable sheet 11 and the exterior nonwoven fabric 12 in the side flaps SF. A plurality of leg-surrounding elastic members 64 may be provided on each side as in the illustrated example, or only one leg-surrounding elastic member 64 may be provided on each side.

(fastening tape)
As shown in FIGS. 1, 2 and 6, the fastening tape 13 includes a sheet base material having a tape attachment portion 13C fixed to the side of the diaper and a tape body portion 13B projecting from the tape attachment portion 13C. and an engaging portion 13A for the ventral side provided at an intermediate portion in the width direction WD of the tape main body portion 13B of the sheet base material, and the leading end side of the engaging portion 13A serves as a knob portion. be. The tape attachment portion 13C of the fastening tape 13 is sandwiched between the gather sheet 62 forming the inner layer of the side flap SF and the exterior nonwoven fabric 12 forming the outer layer, and is adhered to these sheets with a hot-melt adhesive. Also, the engaging portion 13A is fixed to the sheet base material with an adhesive.

A hook member (male member) of a mechanical fastener (surface fastener) is suitable for the locking portion 13A. The hook material has a large number of engaging projections on its outer surface side. As for the shape of the engaging protrusion, there are L-shaped, J-shaped, mushroom-shaped, T-shaped, and double J-shaped (a shape in which J-shaped ones are joined back to back). may be in the shape of Of course, an adhesive layer can also be provided as a locking portion of the fastening tape 13 .

The sheet base material forming the tape attachment portion 13C to the tape body portion 13B includes various nonwoven fabrics such as spunbond nonwoven fabric, air-through nonwoven fabric, and spunlace nonwoven fabric, as well as plastic films, polylaminated nonwoven fabrics, paper, and composite materials thereof. can be used.

(target sheet)
It is preferable to provide a target sheet 12T having a target for facilitating the fastening at the fastening location of the fastening tape 13 in the ventral portion F. As shown in FIG. When the engaging portion 13A is a hook material, the target sheet 12T may be one in which a large number of loop threads are provided on the surface of a sheet base material made of a plastic film or a non-woven fabric so that the engaging protrusions of the hook material can be entangled. In the case of the adhesive material layer, a sheet substrate made of a plastic film having a smooth surface and having high adhesiveness and having a release treatment applied to the surface thereof can be used. Further, when the locking portion of the fastening tape 13 in the ventral portion F is made of nonwoven fabric, for example, when the exterior nonwoven fabric 12 in the illustrated example is made of nonwoven fabric, and the locking portion 13A of the fastening tape 13 is made of a hook material, Alternatively, the target sheet 12T may be omitted, and the hook material may be entwined with the nonwoven fabric of the outer nonwoven fabric 12 for engagement. In this case, a target sheet 12T may be provided between the exterior nonwoven fabric 12 and the liquid-impermeable sheet 11. FIG.

(Absorber)
1, 3, 5 and 15, the absorbent body 70 is a part that absorbs and retains the liquid content of excrement. The absorber 70 can be adhered to at least one of its front and back members via an adhesive 50h such as a hot-melt adhesive.

The absorber 70 is surrounded by a joint portion 54 of a liquid-permeable upper sheet 51 and a lower sheet 52, and has a large number of cells 55 in which the upper sheet 51 and the lower sheet 52 are not joined. It is preferable that the cell absorbent sheet 50 has (small chambers) and granules containing superabsorbent polymer particles 53 contained in the cells 55 .

The cell absorbent sheet 50 will be explained in more detail. As shown in an enlarged view in FIG. 7, the cell absorbing sheet 50 is surrounded by an upper sheet 51, a lower sheet 52 disposed on the back side, and a joint 54 between the upper sheet 51 and the lower sheet 52. It also has cells (small chambers) 55 where the upper sheet 51 and the lower sheet 52 are not joined, and superabsorbent polymer particles 53 contained in the cells 55 . A large number of cells 55 are arranged at intervals corresponding to the joints 54 . In this way, by distributing and holding the superabsorbent polymer particles 53 in a large number of cells 55 which are entirely surrounded by the joints 54, uneven distribution of the superabsorbent polymer particles 53 in the cell absorbent sheet 50 can be prevented.

At least one of the upper sheet 51 and the lower sheet 52 in the cell 55 is outside the cell 55 in the unfolded state in order to facilitate the arrangement of the superabsorbent polymer particles 53 during manufacturing and to secure the volume after absorption expansion. Although it is preferable that the recessed portion 50c is recessed inward, the superabsorbent polymer particles 53 may simply be sandwiched between the upper sheet 51 and the lower sheet 52 without the recessed portion 50c.

The recess 50c can be formed by subjecting the target sheet to shaping such as embossing. In addition, by this embossing, convex portions 50p that bulge outward are formed in the portions of the target sheet that are located in the respective cells 55. As shown in FIG. That is, when the concave portions 50c are formed in the upper sheet 51 by embossing, the portions of the upper sheet 51 located in the respective cells 55 are pushed upward to form convex portions 50p that bulge upward. Although the depth 50d of the concave portion 50c is not particularly limited, it is preferably about 1.0 to 7.0 mm, particularly about 1.0 to 5.0 mm.

Although the dimension of the convex portion 50p can be determined as appropriate, from this point of view, the dimension 55L in the front-rear direction LD of the convex portion 50p of the upper sheet 51 is 6 to 30 mm, and the width direction of the convex portion 50p of the upper sheet 51 is 6 to 30 mm. The dimension 55W of WD 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. ~7.0 mm is preferred.

On the other hand, as shown in FIGS. 7(b) and 13(a), etc., it is preferable that a middle sheet 80 made of nonwoven fabric is interposed between the upper sheet 51 and the lower sheet 52. ), the middle sheet 80 may not be provided. When the intermediate sheet 80 is provided, three layers of the upper sheet 51, the intermediate sheet 80 and the lower sheet 52 are joined at the joining portion 54. FIG. In addition, it is preferable that the middle sheet 80 is compressed in the thickness direction at the joints 54 and swells into the recesses 50c at the portions located in the cells 55 (in other words, the fiber density decreases as the distance from the joints increases). . As a result, the concave portion 50c (and thus the convex portion) is less likely to be crushed by the pressure applied when the product is packaged or when the product is mounted. Or shape restoration is promoted to a volume close to it. When excreted fluid is absorbed, the superabsorbent polymer expands the interstices between the fibers and enters the interstices, or easily compresses the middle sheet 80 , or both, so that the middle sheet 80 expands. Its presence is less likely to inhibit the expansion of superabsorbent polymer particles 53 . Furthermore, since the fibers of the middle sheet 80 that spread within the recessed portion 50c secure liquid passages to the individual superabsorbent polymer particles 53, a decrease in diffusibility is suppressed even after the superabsorbent polymer particles 53 begin to expand. and gel blocking is less likely to occur. Therefore, these synergistic effects improve the absorption speed (particularly at the initial stage of absorption) of the disposable diaper provided with the cellular absorbent sheet 50 .

(upper sheet)
The upper sheet 51 is preferably a highly absorbent nonwoven fabric having a Klemm water absorbency of 100 mm or more. By providing such an upper sheet 51, as indicated by the arrow in FIG. It can be absorbed and held by the particles 53 . Therefore, the absorbability of the viscous liquid by the absorber 70 can be significantly improved. In particular, when the cell absorption sheet 50 has the superabsorbent polymer particles 53 adjacent to the back surface of the upper sheet 51, the viscous liquid N absorbed and diffused by the upper sheet 51 can be efficiently delivered to the superabsorbent polymer particles. preferable.

It is particularly preferable that the superabsorbent nonwoven fabric forming the upper sheet 51 has a Klemm water absorbency of 130 mm or more. The upper limit of the Klemm water absorbency of the highly absorbent nonwoven fabric forming the upper sheet 51 is not particularly limited, but is preferably about 180 mm, and particularly preferably about 160 mm.

The water retention capacity under load of the highly absorbent nonwoven fabric 42 of the upper sheet 51 is preferably greater than 0 g and 0.15 g or less, and particularly preferably greater than 0 g and 0.12 g or less. The non-load water retention capacity of the highly absorbent nonwoven fabric 42 of the upper sheet 51 is preferably greater than 0 g and no greater than 0.7 g, and particularly preferably greater than 0 g and no greater than 0.3 g.

The superabsorbent nonwoven fabric forming the upper sheet 51 is not limited by the material and manufacturing method, but is a wet-laid nonwoven fabric (especially a wet spunlaced nonwoven fabric) containing 50% or more of pulp fiber or rayon fiber and having a basis weight of 25 to 50 g/m ² . is preferable. Fibers other than pulp fibers or rayon fibers can be synthetic fibers such as olefin-based fibers such as polyethylene or polypropylene, polyester-based fibers, polyamide-based fibers (including single-component fibers and composite fibers such as core-sheath fibers). The use of such a wet-laid nonwoven fabric is preferable because it can quickly absorb and diffuse the viscous liquid due to capillary action caused by minute interstices between fibers. In particular, such a wet-laid nonwoven fabric not only has a high Klemm water absorbency, but is also very thin and flexible, so that the decrease in flexibility and increase in thickness of the cell absorbent sheet 50 as a whole can be suppressed. Although the thickness of the superabsorbent nonwoven fabric forming the upper sheet 51 is not limited, it is preferably about 0.13 to 0.48 mm in terms of basis weight.

As shown in FIG. 17, the superabsorbent nonwoven fabric forming the upper sheet 51 includes a support layer 42b containing synthetic resin long fibers and a pulp layer 42a located on the frontmost side and made only of pulp fibers. Layers, or three or more layers of highly absorbent nonwoven fabric 42 are particularly preferred. Such a highly absorbent nonwoven fabric 42 is preferable because the pulp layer 42a can increase the Klemm water absorbency and the presence of the support layer 42b can increase the strength.

If the upper sheet 51 has the concave portions 50c, the surface area of the upper sheet 51 is increased, and liquid can be supplied to the superabsorbent polymer particles in the cell absorbent sheet 50 over a wider range, which is preferable.

The material of the lower sheet 52 is not particularly limited. preferable. As indicated by the arrows in FIG. 16(b), the non-viscous liquid U such as urine supplied to the cell absorbent sheet 50 is absorbed by the superabsorbent polymer particles 53 in the cell absorbent sheet 50, and the superabsorbent polymer particles 53 The non-viscous liquid U that reaches the lower sheet 52 without being absorbed by the polymer particles 53 is absorbed by the lower sheet 52, retained in the lower sheet 52, diffused, and then the superabsorbent polymer particles in the cell absorbent sheet 50. 53 can be sucked up. The cell-absorbing sheet 50 has joints 54 that do not have superabsorbent polymer particles 53 and continuously extend toward the periphery of the cell-absorbing sheet 50. The gap between the back surface and the facing surface of the cell absorbing sheet 50 also extends continuously toward the periphery of the cell absorbing sheet 50. - 特許庁Therefore, if the water retention capacity of the cell absorbent sheet 50 is low, the non-viscous liquid U that permeates the cell absorbent sheet 50 moves on the liquid-impermeable sheet 11 and seeps out from the periphery of the absorbent body 70 toward the skin. It may adhere to the skin or leak.

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

As the highly absorbent nonwoven fabric forming the lower sheet 52, the same highly absorbent nonwoven fabric as the upper sheet 51 can be suitably used. When the joining portion 54 of the upper sheet 51 and the lower sheet 52 is formed by welding, the highly absorbent nonwoven fabric forming the lower sheet 52 is preferably heat-sealable fibers such as polyethylene fibers and composite fibers containing polyethylene components. Since the highly water-absorbent nonwoven fabric used for the lower sheet 52 is intended to temporarily store a non-viscous liquid U such as urine, it preferably has a larger water holding capacity than the upper sheet 51 . For example, the superabsorbent nonwoven fabric forming the lower sheet 52 preferably has a water holding capacity under load of 2 to 4 times that of the superabsorbent nonwoven fabric of the upper sheet 51 . More specifically, the basis weight of the superabsorbent nonwoven fabric forming the lower sheet 52 is 1.2 to 1.8 times the basis weight of the superabsorbent nonwoven fabric forming the upper sheet 51, or the superabsorbent nonwoven fabric forming the lower sheet 52 is A plurality of highly absorbent nonwoven fabrics equivalent to the upper sheet 51 can be stacked and arranged.

If the lower sheet 52 has the concave portion 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 the case where the lower sheet 52 is flat without being shaped, which is preferable.

The intermediate 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, more preferably 5.6 to 6.6 dtex. The nonwoven fabric of the middle sheet 80 preferably has a porosity of 80 to 98%, 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 superabsorbent polymer particles 53 remain in the middle sheet 80 before and during the absorption of the excreted fluid. It becomes possible to easily enter into the interstices of the fibers. Therefore, since the fibers of the middle sheet 80 spreading in the recesses 50c at the time of absorption ensure liquid passages to the individual superabsorbent polymer particles 53, the diffusibility decreases even after the superabsorbent polymer particles 53 start to expand. 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 10% to 90% of the depth 50d of the recess 50c. and more preferably 70% to 90%. For the same reason, the basis weight of the middle sheet 80 may be appropriately determined, but it is preferable to set it to about 25 to 40 g/m ² within the above thickness range. In order to increase the porosity of the non-woven fabric of the middle sheet 80 (widen the inter-fiber gaps), it is preferable to use crimped fibers as the constituent fibers. Further, if the constituent fibers of the nonwoven fabric of the inner sheet 80 are hydrophilic fibers (including fibers made hydrophilic by a hydrophilizing agent), the water retentivity will be high, and if they are hydrophobic fibers, the diffusibility will be improved. The method of bonding the fibers of the non-woven fabric is not particularly limited, but in order to increase the porosity (widen the inter-fiber gap) and sufficiently bond the fibers to ensure elasticity, the air-through non-woven fabric in which the fibers are bonded by heating with hot air is used as the middle sheet. 80 is preferred.

As long as the surface of the middle sheet 80 facing the recessed portion 50c is inside the recessed portion 50c, it is in contact with the inner surface of the recessed portion 50c as shown in FIGS. Although it is preferable to have them, they may be spaced apart as shown in FIG. 13(b). When the surface of the middle sheet 80 facing the recess 50c is separated from the inner surface of the recess 50c, the separation 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 in the cell 55, the convex portion 50p (the concave portion 50c) may be crushed according to the gap in the product state.

As shown in FIGS. 13(a)-(c) and 14(a), the middle sheet 80 is applied to at least one of the upper sheet 51 and the lower sheet 52 both in the cells 55 and at the joints 54. It may be adhered with a hot melt adhesive 80h, or may not be adhered to both the upper sheet 51 and the lower sheet 52 as shown in FIG. 14(c).

Preferably, substantially all (for example, 95% or more) of the superabsorbent polymer particles 53 are not fixed to the upper sheet 51, the lower sheet 52 and the middle sheet 80, and are freely movable. However, some or almost all (for example, 95% or more) of superabsorbent polymer particles 53 can be adhered or adhered to at least one of top sheet 51 , bottom sheet 52 and middle sheet 80 . FIG. 14(b) shows an example in which some of the superabsorbent polymer particles 53 are adhered to the lower sheet 52 with an adhesive 53h such as a hot-melt adhesive. Also, the superabsorbent polymer particles 53 may be agglomerated to some extent. In particular, when the superabsorbent polymer particles 53 are freely movable within the cells 55, having a hollow portion within the cells 55 causes the superabsorbent polymer particles 53 to move within the cells 55 during use, resulting in noise. Absorption may be inhibited due to shedding or uneven distribution of the superabsorbent polymer particles 53 in the cells 55 . Therefore, in order to solve this problem, as described above, the surface of the middle sheet 80 facing the recess 50c is brought into contact with the inner surface of the recess 50c. Filling the middle sheet 80 with fibers is one preferred form. As a result, the superabsorbent polymer particles 53 are trapped by the fibers of the middle sheet 80 or pressed against the top sheet 51 or the bottom sheet 52, or both, so that they are less likely to move freely. Therefore, while preventing the expansion inhibition of the superabsorbent polymer particles 53, the generation of noise due to the movement of the superabsorbent polymer particles 53 and the absorption inhibition due to the uneven distribution of the superabsorbent polymer particles 53 in the cells 55 are prevented. can do.

As in the examples shown in FIGS. 13(a), (b), and 14(c), the superabsorbent polymer particles 53 are present most on the upper surface of the middle sheet 80, and downward from there. The reduction is preferable because when the user touches the outer surface of the diaper with his/her hands, the presence of the middle sheet 80 makes it difficult for the user to feel the crunchy feel (uncomfortable feeling) of the superabsorbent polymer particles 53 . In particular, when the middle sheet 80 is a bulky nonwoven fabric with a high porosity, the superabsorbent polymer particles 53 can enter the interstices between the fibers of the middle sheet 80 before and during the absorption of the excreted fluid. Absorption rate is further improved. That is, in the initial stage of absorption, absorption progresses on the upper surface of the middle sheet 80 where many superabsorbent polymer particles 53 are distributed, but the speed is limited. Therefore, in the initial stage of absorption, a large amount of excreted fluid also enters the middle sheet 80 where there are few superabsorbent polymer particles 53, and is absorbed by the superabsorbent polymer particles 53 in the middle sheet 80, or It is either temporarily stored until absorbed by particles 53 or diffuses into surrounding cells 55 . The excrement that has diffused around is absorbed by the superabsorbent polymer particles 53 in the middle sheet 80 existing there, or is sucked up by the superabsorbent polymer particles 53 existing above. As each superabsorbent polymer particle 53 absorbs excreted fluid, the superabsorbent polymer expands the interstices between the fibers and expands while entering the interstices or compressing the middle sheet 80 . Due to such an absorption mechanism, the excreted liquid is rapidly diffused over a wide area of the cell absorbent sheet 50 and is received inside the cell absorbent sheet 50, so that not only the absorption speed is improved but also the reversion prevention property is achieved. will be excellent. Moreover, in order to exhibit such an absorption mechanism satisfactorily, it is preferable that the concave portion 50c is formed at least in the portion of the upper sheet 51 that constitutes each cell 55. As shown in FIG.

The degree of distribution of the superabsorbent polymer particles 53 in the cells 55 can be appropriately determined, but in general, the weight ratio of the superabsorbent polymer particles 53 present on the upper surface of the middle sheet 80 is 50% or more of the total amount. and the weight percentage of the superabsorbent polymer retained within the middle sheet 80 (that is, not on the bottom sheet 52) is preferably 45% or more of the total weight.

Of course, the distribution of the superabsorbent polymer particles 53 within the cells 55 is not limited to this. Therefore, if the absorbability from the superabsorbent nonwoven fabric forming the lower sheet 52 is emphasized, as shown in FIG. , and a distribution that decreases upward from there. Further, as shown in FIG. 14(a), the amount of superabsorbent polymer particles 53 present on the upper surface of the middle sheet 80 and the upper surface of the lower sheet 52 is distributed in a larger amount than in the portion between them. may Furthermore, although not shown, the superabsorbent polymer particles 53 can be distributed such that the greatest amount of the superabsorbent polymer particles 53 exists in the middle of the thickness direction of the intermediate sheet 80 and decreases upward and downward from there. This form can be formed by forming the middle sheet 80 from two layers of nonwoven fabric and sandwiching superabsorbent polymer particles 53 between the layers.

The weight per unit area of the superabsorbent polymer particles 53 may be determined as appropriate, and for example, in normal cases, it can be 150 to 250 g/m ² . In general, if the basis weight of the superabsorbent polymer particles 53 is less than 150 g/m ² , it is difficult to secure the absorption capacity ^. It makes it easier to convey the rough texture (discomfort) to the hand.

The planar shape of the cells 55 can be determined as appropriate, and can be hexagonal, rhombic, square, rectangular, circular, oval, etc. as shown in FIG. It is desirable that they are rectangular, and that they be arranged without gaps as shown in the illustrated example. In addition to arranging the cells 55 having the same shape and the same size, it is also possible to arrange a combination of a plurality of types of cells 55 having at least one of different shapes and sizes (not shown).

The planar arrangement of the cells 55 (that is, the aggregation of the superabsorbent polymer particles 53 is also the same) can be appropriately determined, but a regularly repeated planar arrangement is preferable, and an orthorhombic lattice as shown in FIG. 12(b), a hexagonal lattice (also referred to as a staggered pattern), a square lattice as shown in FIG. 12(c), a rectangular lattice as shown in FIG. 12(e) (as shown in the figure, a form in which two groups of a large number of parallel oblique rows are provided so as to intersect with each other) (these are 90 degrees with respect to the stretching direction) In addition to those regularly repeated such as those inclined at an angle of less than a degree), groups of cells 55 (arrangement in group units may be regular or irregular, and may be patterns, letters, etc.) are regular. It can also be repeated indefinitely.

The dimension of each cell 55 can be determined as appropriate. For example, the dimension 55L in the front-rear direction LD (equal to the dimension in the front-rear direction LD of the convex portion 50p) can be about 6 to 30 mm, and the dimension 55W in the width direction WD can be set. (which is equal to the dimension in the width direction WD of the convex portion 50p) can be about 7 to 50 mm. The area of each cell 55 can be about 31 to 1650 mm ² .

The joint 54 for joining the upper sheet 51 and the lower sheet 52 is desirably joined by welding the upper sheet 51 and the lower sheet 52 like ultrasonic welding or heat sealing. It may be joined.

The joints 54 of the upper sheet 51 and the lower sheet 52 are arranged so as to surround each cell 55, and as long as they form boundaries between adjacent cells, they form a dotted line (intermittent in the direction surrounding each cell 55) as shown in the figure. ), it can also be formed in a continuous line. When the joints 54 are intermittently formed, it is preferable that there are no superabsorbent polymer particles 53 or less superabsorbent polymer particles 53 between the joints 54 in the direction surrounding the cells 55 than in the cells 55 . In particular, if the joints are provided in dotted lines (intermittently), the fiber group of the middle sheet will pass through the adjacent joints and extend over a large number of cells. Therefore, liquid diffusion passages are formed between the adjacent joints, so that the absorption speed is improved by improving the liquid diffusibility across the cells.

As shown in FIG. 10, the joints 54 are weak joints 54b that can be peeled off by the expansion force of the superabsorbent polymer particles 53 in the adjacent cells 55. It may be a strong joint 54 a that basically does not separate due to the expansive force of the absorbent polymer particles 53 . In order to cope with the expansion of the superabsorbent polymer particles 53 to the volume of the individual cells 55 or more, it is preferable that part or all of the joints 54 are weak joints 54b. By having the weak bonding portion 54b, the cells 55 adjacent to each other across the weak bonding portion 54b are exfoliated and united by the absorption expansion pressure of the superabsorbent polymer particles 53 in the cell 55 to form one large cell 55. becomes possible.

On the other hand, the strong bonding portion 54a is a portion that basically does not separate even if the cells 55 on both sides thereof absorb and expand. It has effects such as preventing the flow of the gelled product and reducing the contact area on the surface side. Therefore, by combining this with the weak joint, it is possible to construct a cell absorbent sheet 50 having various characteristics as described later. The joints 54 located on the outermost side in the width direction WD are strong joints 54a because there is a risk that the superabsorbent polymer particles 53 or gelled products thereof may leak out to the sides of the cell absorbent sheet 50 if the joints 54 are peeled off. is desirable. From a similar point of view, the upper sheet 51 and the lower sheet 52 are preferably extended to some extent outside the cell 55 forming region in the width direction WD, and the extended portions are provided with edge joint portions 54c for reinforcement. preferable.

The difference in bonding strength can be easily formed by changing the area of the bonding portion 54, but is not limited to this. It is also possible to adopt a method of making the type of the suffix different depending on the part. In particular, when the joint portion 54 is formed by welding the upper sheet 51 and the lower sheet 52, the weak joint portion 54b can be formed only by forming the joint portion 54 into a dotted line and widening the interpoint spacing 54D. Since the portion 54 is a boundary between adjacent cells 55, if the point spacing 54D is too wide, the gap between the adjacent cells 55 will increase, making it easier for the superabsorbent polymer particles 53 to move. Therefore, if the dotted-line weak joint 54b is formed by combining the width 54W of the joint 54 and the wideness or narrowness of the inter-point spacing 54D, the weak joint 54b portion is likely to separate even though the gap is small. Become.

The size of the joining portion 54 that joins the upper sheet 51 and the lower sheet 52 can be determined as appropriate. It can be about 0 to 1.8 mm. Further, when the joints 54 are formed in a dotted line (intermittently in the direction surrounding the cells 55), the dimension 54L of the joints 54 in the direction surrounding the cells 55 is about 0.6 to 1.5 mm, and the point interval 54D is 0. 0.8 to 3.0 mm is preferable. In particular, in the case of the strong joint 54a, the width 54W is approximately 1.3 to 1.8 mm, the dimension 54L of the joint 54 is approximately 1.0 to 1.5 mm, and the point spacing 54D is 0.8 to 2.0 mm. It is preferable to set it to a degree. In the case of the weak joint 54b, 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 interval 54D is 1.5 to 3.0 mm. It is preferable to set it to a degree.

In order to make the weak joint 54b detachable, the volume at the time of saturated absorption of the superabsorbent polymer particles 53 in the cell 55 is sufficiently larger than the volume of the cell 55 adjacent to the weak joint 54b. The type and amount of superabsorbent polymer particles 53 placed within each cell 55 can be determined. In addition, in order to basically prevent the strong bonding portion 54a from peeling, the high absorbency contained in the unitable cell 55 is larger than the volume after the uniting of the unitable cell 55 by peeling the weak bonding portion 54b. The type and amount of the superabsorbent polymer particles 53 arranged in each cell 55 can be determined so that the volume of the polymer particles 53 at saturation absorption is small.

The width of the joint 54 when the joint 54 is formed in the shape of a continuous line and the width 54W when the joint 54 is formed in the shape of a dotted line are constant in the direction surrounding the cell 55, and can also be varied. . Further, the shape of each joint portion 54 in the case where the joint portion 54 is formed in the shape of a dotted line can be determined as appropriate, and in addition to being all the same, the shape can also be different depending on the part. Especially when each cell 55 has a polygonal shape, it is preferable to provide a joint portion 54 at least one of the intermediate position of each side and the position of each vertex. Further, in the case of the strong joint 54a, it is preferable to be provided at each vertex position. is preferable because it proceeds smoothly.

As shown in FIGS. 8 and 11, in the middle region of the cell absorbent sheet 50 in the width direction WD, a longitudinal strong joint line 58 where the strong joint portion 54a continues in the front-rear direction LD, and low-expansion cells adjacent to both sides thereof. It is preferable that a diffusibility improving portion 57 consisting of 55s is provided. The low-expansion cells 55s of the diffusibility-improving portion 57 contain less superabsorbent polymer particles 53 per unit area than the cells 55 adjacent to both sides of the diffusibility-improving portion 57, and the diffusibility-improving portion The joints 54 between the cells 55 adjacent to both sides of the 57 are weak joints 54b. In this case, as shown in FIG. 10, due to the difference in swelling between the diffusibility-improving portion 57 and its surrounding portion, a wide groove is formed with the diffusibility-improving portion 57 as the bottom, The groove promotes liquid diffusion. In this state, due to the expansion force of the superabsorbent polymer particles 53 in the cells 55 around the diffusibility-enhancing portion 57, the weak joints between the low-expansion cells 55s of the diffusibility-enhancing portion 57 and the cells 55 on both sides thereof This continues until 54b is removed, and the strong joint 54a does not come off even after the weak joint 54b is removed. Therefore, although the width of the groove is narrowed, a groove whose bottom is the strong joint 54a remains, and diffusion is maintained. That is, the width of the groove is wide at the initial stage of absorption when diffusion of a large amount of excreted fluid is important, and after that, the low-expansion cells 55s of the diffusibility-enhancing portion 57 and the surrounding cells 55 are widened so as to prevent problems such as gel blocking from occurring. However, the strongly bonded portion 54a leaves a groove and maintains the diffusibility improving effect.

The amount of the superabsorbent polymer particles 53 contained in the low-expansion cells 55s is preferably ⅓ or less of that in the adjacent cells 55 in terms of weight ratio, and particularly preferably not contained at all.

8 and 11, the strong joint 54a and the weak joint 54e with relatively high joint strength are represented by thick dotted lines, and the other weak joints 54b and 54f are represented by thin dotted lines. Cells 55 containing absorbent polymer particles 53 (that is, cells 55 excluding low-expansion cells 55s and empty cells 56 described later) are hatched in FIG.

The diffusion improving portion 57 may be provided over the entire length of the cell absorbent sheet 50 as shown in FIG. 8, and as shown in FIG. It may be provided only in the range covering both sides). 8 and 11, the diffusibility improving part 57 is provided at one place in the center of the width direction WD, and although not shown, may be provided at a plurality of places at intervals in the width direction WD. can.

When the cells 55 can be combined with each other over the entire front-rear direction LD of the cell absorbent sheet 50, the gelled product of the superabsorbent polymer particles 53 expanded during absorption can move greatly in the front-rear direction LD within the united cells 55. The gelled material may collect in low places such as the crotch area and deteriorate the feeling of wearing. Therefore, as shown in FIG. 8, a plurality of lateral strong joint lines 59, which are portions where the strong joint portion 54a continues continuously or intermittently in the width direction WD or the oblique direction, are provided at intervals in the front-rear direction LD. It is the preferred form. As a result, the strong bonding portion 54a, which basically does not peel off during absorption, can prevent the gelation of the superabsorbent polymer particles 53 from moving in the front-rear direction LD, and can prevent the shape of the cell absorption sheet 50 from collapsing. . Of course, as shown in FIG. 11, it is also possible to adopt a configuration that does not have such a lateral strong joint line 59. FIG.

In particular, as in the embodiment shown in FIG. 8, the longitudinal strong bonding line 58, which is the portion where the strong bonding portion 54a continues in the front-rear direction LD over the entire length of the cell absorbent sheet 50, is located on the side of the cell 55 located on the outermost side in the width direction WD. Along the edge, it is provided on both sides in the width direction WD, and is also provided in the middle of these width directions WD. In the case of the portion continuing in the width direction WD or the oblique direction as shown in FIG. It does not move outside the maximum expansion section 55G, and can effectively prevent the shape of the cell absorption sheet 50 from collapsing during absorption. In addition, the liquid diffusion property in the vertical direction is improved by the vertical strong bonding line 58 where the strong bonding portion 54a continues in the front-rear direction LD, and the horizontal strong bonding where the strong bonding portion 54a continues in the width direction WD or oblique direction. Lines 59 improve lateral liquid diffusion. For example, in the form shown in FIG. 8, assuming that urine is excreted at the position of symbol Z, the urine diffuses around that point as shown in FIG. 53 is absorbed. At this time, as shown in FIGS. 9 and 10, in the cells 55 in which the expansion pressure of the superabsorbent polymer particles 53 inside has increased, the weak joints 54b around the cells 55 are unable to withstand the expansion pressure and peel off, Merge with adjacent cells 55 . This coalescence continues as long as the absorption expansion of the superabsorbent polymer particles 53 can separate the weak joints 54b, and can proceed to the cells 55 having the strong joints 54a around them.

The size, shape, and arrangement of the maximum expansion section 55G (that is, the arrangement of the strong joints 54a) can be determined as appropriate. Even if the cells 55 are formed to be long and narrow, the shape of the cells 55 after being combined becomes a shape that is difficult to swell.

In the embodiment shown in FIGS. 8 to 10, longitudinal strong bonding lines 58 are provided at the central portion and both side portions of the cell absorbent sheet 50 in the width direction WD, and the horizontal strong bonding lines 59 are provided at the central longitudinal strong bonding line. It forms a zigzag shape extending in the front-rear direction while repeatedly bending left and right between the line 58 and the longitudinal strong joining lines 58 on both sides. As a result, a substantially triangular maximum expansion section 55G having a vertex at the position of the central longitudinal strong junction line 58 and a substantially triangular maximum expansion section 55G having a vertex at the position of the vertical strong junction line 58 on both sides. , are alternately formed in the front-rear direction. When the lateral strong-bonding lines 59 are formed in a zigzag shape in this manner, the lateral liquid diffusion can be efficiently promoted with a small number of the lateral strong-bonding lines 59, and the maximum expansion section 55G has a substantially triangular shape that is easy to swell. , the increase in cell volume with respect to the number of coalesced cells 55 is also excellent.

Only the longitudinal strong joint line 58 may be provided without providing the low-expansion cells 55s. In this case, since the strong joint portion 54a does not come off when excreted liquid is absorbed, the diffusion is improved by leaving a groove with the strong joint portion 54a as the bottom.

On the other hand, as shown in FIG. 8 and the like, an empty cell 56 may be provided in which the amount of superabsorbent polymer particles 53 contained per unit area is less than that of the other cells. In FIG. 11, cells 55 containing superabsorbent polymer particles 53 (that is, cells 55 excluding low-expansion cells 55s and empty cells 56, which will be described later) are shaded. Among them, the hatched area in FIG. 8 is assumed to be the dispersion area 53A of the superabsorbent polymer particles 53 at the time of manufacture. When the superabsorbent polymer particles 53 are movable within the cell 55, the product does not fix the position of the superabsorbent polymer particles 53 within the cell 55. Superabsorbent polymer particles 53 can be distributed throughout the interior. The amount of the superabsorbent polymer particles 53 contained in the empty cells 56 is preferably 1/2 or less of that of the other cells in terms of weight ratio, and it is particularly preferable not to contain the particles at all. For example, since the front and rear ends of the cell-absorbing sheet 50 are formed by cutting into individual cell-absorbing sheets 50 during manufacturing, if the superabsorbent polymer particles 53 are contained in this position, the blade of the cutting device will be cut off. Life may be shortened. Therefore, it is desirable that at least the cells 55 at positions through which the front and rear ends of the cell absorbent sheet 50 pass are empty cells 56 . In addition, by making the cells 55 on both sides of the middle of the cell absorbing sheet 50 in the front-rear direction LD empty cells 56, this portion does not expand much even after absorption, and therefore the cell absorbing sheet 50 remains in the legs even after absorption. Shaped to fit the surroundings.

In the above example, only the superabsorbent polymer particles 53 are included in the cells 55, but powders other than the superabsorbent polymer particles, such as deodorant particles, can also be included together with the superabsorbent polymer particles 53. .

(superabsorbent polymer particles)
As the superabsorbent polymer particles 53, those used in this type of absorbent article can be used as they are. The particle size of the superabsorbent polymer particles 53 is not particularly limited. It is preferable that the proportion of the following particles is 10% by weight or less and the proportion of particles of 106 μm or less is 10% by weight or less. In addition, the measurement of these particle diameters is performed as follows. That is, 500 μm, 180 μm, 106 μm standard sieves (JIS Z8801-1: 2006) and a saucer are arranged in this order from the top, and 10 g of a sample of superabsorbent polymer particles is put into the top 500 μm sieve, After sieving (shaking for 5 minutes), weigh the particles remaining on each sieve. As a result of this sieving, the weight ratio of the sample remaining on each of the 500 μm, 180 μm, and 106 μm sieves and the sample remaining on the saucer to the input amount was calculated as the ratio of particles over 500 μm, the ratio of particles up to 500 μm and over 180 μm, respectively. the ratio, the ratio of particles larger than 106 μm and 180 μm or less, and the ratio of particles 106 μm or less.

Although the superabsorbent polymer particles 53 can be used without any particular limitation, those having a water absorption of 40 g/g or more are suitable. Moreover, it is preferable that the superabsorbent polymer particles 53 are produced by a crushing method because gel blocking is less likely to occur. The superabsorbent polymer particles 53 include starch-based, cellulose -based, and synthetic polymer-based particles, including starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, sodium carboxymethyl cellulose . and acrylic acid (salt) polymers can be used. As for the shape of the superabsorbent polymer particles 53, a powdery or granular shape that is commonly used is suitable, but other shapes can also be used.

As the superabsorbent polymer particles 53, those having a water absorption rate of 70 seconds or less, particularly 40 seconds or less are preferably used. If the water absorption rate is too slow, so-called backflow, in which the liquid supplied into the absorbent body 70 returns to the outside of the absorbent body 70, is likely to occur.

Moreover, as the superabsorbent polymer particles 53, those having a gel strength of 1000 Pa or more are preferably used. As a result, stickiness after liquid absorption can be effectively suppressed.

(packaging sheet)
As shown in FIGS. 3 and 15( a ), the absorbent body 70 can be wrapped with a wrapping sheet 45 . In this case, one packaging sheet 45 can be wrapped around the front and rear surfaces and both side surfaces of the absorber 70, or two packaging sheets 45 can be sandwiched between the front and back surfaces for packaging. As the packaging sheet 45, tissue paper, particularly crepe paper, nonwoven fabric, poly-laminated nonwoven fabric, a perforated sheet, or the like can be used. However, it is desirable that the sheet is such that the superabsorbent polymer particles 53 do not escape. When a nonwoven fabric is used for the packaging sheet 45, a hydrophilic SMS nonwoven fabric (SMS, SSMMS, etc.) is particularly suitable, and its material can be polypropylene, polyethylene/polypropylene composite material, or the like. The nonwoven fabric used for the packaging sheet 45 preferably has a basis weight of 5 to 40 g/m ² , particularly 10 to 30 g/m ² .

As shown in FIG. 15(b), the packaging sheet 45 is wrapped from the back surface of the absorbent body 70 to both sides of the upper surface of the absorbent body 70 via both sides in the width direction WD of the absorbent body 70, and the width of the upper surface of the absorbent body 70 is increased. It is preferable to provide an area 45S that is not covered with the packaging sheet 45 in the intermediate portion in the direction WD. The absorbent body 70 is generally covered with a packaging sheet 45 in order to prevent the superabsorbent polymer particles from leaking out during manufacture, before use, or after absorption. Considering the properties, it is desirable that the upper sheet 51 comes into contact with the viscous liquid N quickly. Therefore, as shown in FIG. 15(b), it is desirable to limit the coverage area of the packaging sheet 45 and expose the upper sheet 51 on the upper surface of the absorber 70. As shown in FIG. Even with such a structure, since the upper sheet 51 is based on a highly absorbent nonwoven fabric having a high Krem water absorbency (that is, dense), the absorbent body 70 as a whole is covered with a superabsorbent polymer similar to the packaging sheet 45. This will exhibit the effect of preventing particles from leaking out.

<Description of terms in the specification>
When the following terms are used in the specification, they shall have the following meanings, unless stated otherwise in the specification.

"MD direction" and "CD direction" mean the flow direction (MD direction) and the transverse direction (CD direction) perpendicular to this in the manufacturing equipment, one of which is the front-back direction of the product, 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. The fiber orientation is the direction along which the fibers of the nonwoven fabric are aligned. It can be determined by a simple measurement method for determining the orientation direction.

・"Front-back direction" means the direction (longitudinal direction) indicated by symbol LD in the figure, and "width direction" means the direction (left-right direction) indicated by WD in the figure. are orthogonal.

- The "front side" means the side closer to the wearer's skin when worn, and the "back side" means the side farther from the wearer's skin when worn.

- "Front" means the side of the member that is closer to the wearer's skin when worn, and "back" means the side that is farther from the wearer's skin when worn.

The "deployed state" means a flat unfolded state without contraction or slack.

"Elongation rate" means a value when the natural length is taken as 100%. For example, an elongation rate of 200% is synonymous with an elongation ratio of 2 times.

"Artificial urine" contains urea: 2 wt%, sodium chloride: 0.8 wt%, calcium chloride dihydrate: 0.03 wt%, magnesium sulfate heptahydrate: 0.08 wt%, and deionized water: 97 wt%. 09 wt% and used at a temperature of 37°C 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. and 60% RH for 3 hours, then returned to room temperature, and the gel strength is measured with a card meter (Curdmeter-MAX ME-500, manufactured by I. techno Engineering).

"Matsuke" is measured as follows. After pre-drying the sample or test piece, it is left in a test room or apparatus under standard conditions (test location: temperature 23±1° C., relative humidity 50±2%) to a constant weight. Pre-drying refers to making a sample or test piece constant weight in an environment at a temperature of 100°C. Fibers with an official moisture content of 0.0% do not need to be pre-dried. Using a sampling template (100 mm x 100 mm), a sample with dimensions of 100 mm x 100 mm is cut from the constant weight specimen. The weight of the sample is measured, multiplied by 100 to calculate the weight per square meter, and used as basis weight.

"Thickness" is automatically measured using an automatic thickness gauge (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. That is, a portion of the middle sheet other than the joint portion is cut into a rectangular shape and used as a sample. Measure the length, width, thickness and weight of the sample. Using the raw material density of the nonwoven fabric, calculate the virtual weight when the volume is the same as the sample and the porosity is 0%. Substitute the sample weight and virtual weight into the following formula to obtain the porosity.
Porosity = [(virtual weight - sample weight) / virtual weight] x 100

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

"Water absorption rate" is defined as "Time to end point" when JIS K7224-1996 "Test method for water absorption rate of superabsorbent polymer" is performed using 2g of superabsorbent polymer and 50g of physiological saline. do.

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

"Water retention capacity" means what is measured by the following method. A test piece of 10 cm in the MD direction×10 cm in the CD direction (area 100 cm ² ) is prepared, and the weight before absorption is measured. Next, after immersing the test piece in artificial urine for 5 seconds, any one corner is lightly pinched with the thumb and index finger (lightly pinched so as not to squeeze out water as much as possible), and the opposite corner is down. and leave it for 30 seconds to remove the drops. After that, when measuring the "water retention capacity under load", the test piece is placed on top of 8 sheets of filter paper (150 mm long x 150 mm wide), and the entire upper surface of the test piece is 100 mm long x 100 mm long. A square column-shaped weight (weight: 3 kg) having a bottom surface with a width of 100 mm is placed on the test piece. When measuring the "water retention capacity under no load", place the test piece on 8 layers of filter paper and measure the weight of the test piece after absorption after 5 minutes without placing anything on it. do. Based on these measurement results, the values obtained by converting the difference between the weight after absorption and the weight before absorption per 10 cm ² area are defined as "water retention capacity under load" and "water retention capacity without load".

Unless otherwise specified, the dimension of each part means the dimension in the unfolded state, not in the natural length state.

Unless otherwise specified, the test or measurement shall be conducted in a laboratory or equipment under standard conditions (temperature of 23±1°C, relative humidity of 50±2%). .

INDUSTRIAL APPLICABILITY The present invention can be used not only for tape-type disposable diapers as described above, but also for general absorbent articles such as underpants-type disposable diapers, pad-type disposable diapers, and sanitary napkins.

LD... Front-back direction, 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 part, 13B... Tape body part, 13C... Tape attachment part, 30... Top sheet, 40... Intermediate sheet, 42... Super absorbent nonwoven fabric, 42a... Pulp layer, 42b... Support layer, 45... Packaging sheet, 50... Cell absorption sheet, 50c ... concave portion 50d ... depth 50p ... convex portion 51 ... upper sheet 52 ... lower sheet 53 ... superabsorbent polymer particles 54 ... joint portion 54a ... strong joint portion 54b ... weak joint portion 54c ... Edge junction, 55 Cell, 55G Maximum expansion section, 55s Low expansion cell, 56 Empty cell, 57 Diffusion improving part, 58 Longitudinal strong junction line, 59 Horizontal strong junction line, 60 Rise Gather, 62... Gather sheet, 70... Absorbent body, 80... Middle sheet.

Claims (6)

An absorbent body, a liquid-permeable top sheet arranged on the front side of the absorbent body , and a liquid-impermeable sheet arranged on the back side of the absorbent body ,
The absorbent body includes a liquid-permeable upper sheet and a lower sheet, a cell surrounded by a joint portion of the upper sheet and the lower sheet, and a portion in which the upper sheet and the lower sheet are not joined, and a cell absorbent sheet having a granular material containing superabsorbent polymer particles housed in
The upper sheet is a highly absorbent nonwoven fabric having a Klemm water absorbency of 130 mm or more,
The lower sheet is a highly absorbent nonwoven fabric having a Krem water absorbency of 50 to 100 mm,
The water retention capacity under load of the upper sheet is greater than 0 g and equal to or less than 0.15 g,
The water retention capacity under load of the lower sheet is 2 to 4 times the water retention capacity under load of the upper sheet,
a portion of the upper sheet located in each cell is pushed upward to form a convex portion on the upper surface of the upper sheet and a concave portion on the lower surface thereof;
A middle sheet made of nonwoven fabric is interposed between the upper sheet and the lower sheet,
The middle sheet is compressed in the thickness direction at the joint portion, and swells at the portion located in the cell and enters the recess,
A surface of the middle sheet facing the recess is in contact with the inner surface of the recess,
Between the middle sheet and the top sheet, the superabsorbent polymer particles are arranged adjacent to the back surface of the top sheet,
the superabsorbent polymer particles are not fixed to the top sheet;
An absorbent article characterized by: The superabsorbent nonwoven fabric forming the upper sheet is a wet-laid nonwoven fabric containing 50% or more of pulp fiber or rayon fiber and having a basis weight of 25 to 50 g/m ² ,
The absorbent article according to claim 1. The wet-laid nonwoven fabric has a support layer containing synthetic resin long fibers, and a pulp layer located on the outermost side and made only of pulp fibers,
The upper sheet and the lower sheet are welded together at the joint,
The absorbent article according to claim 2. The superabsorbent polymer particles are present most on the upper surface of the middle sheet and decrease from there toward the bottom sheet.
The absorbent article according to any one of claims 1-3. The lower sheet is a highly absorbent nonwoven fabric having 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.
The absorbent article according to any one of claims 1-3. the amount of superabsorbent polymer particles present on the top surface of the middle sheet and on the top surface of the bottom sheet is greater than the portion between them;
The absorbent article according to claim 5.

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