JP7149771B2 - Absorber - Google Patents

Description

The present invention relates to absorbent bodies.

Absorbent articles are known which comprise an absorbent body (also called SAP sheet) with a high proportion of Super Absorbent Polymer (SAP).

For example, in Patent Document 1, the entire absorbent core has a structure wrapped in an upper core wrap sheet and a lower core wrap sheet, and the upper core wrap sheet has a convex shape toward the wearer's skin side. An absorbent body is disclosed which is a nonwoven fabric having an uneven structure such that

JP 2015-116360 A

In an absorbent body with a high ratio of superabsorbent polymer, when the superabsorbent polymer absorbs body fluid and swells, the volume of the region formed inside the core wrap sheet containing the superabsorbent polymer is too small. However, the swelling of the superabsorbent polymer is limited, and the absorbent capacity of the superabsorbent polymer tends to be low.
Here, in the absorbent body described in Patent Document 1, the core wrap sheet is provided with an uneven region. Therefore, the core wrap sheet can be stretched by stretching the uneven region corresponding to the swelling of the superabsorbent polymer. Thereby, the swelling of the superabsorbent polymer is less likely to be restricted.
However, in the absorbent body described in Patent Document 1, since the core wrap sheet of the absorbent body has the uneven area, a gap is likely to occur between the uneven area and the top sheet, and the transfer of body fluid from the top sheet to the absorbent body is inhibited. may be hindered. Therefore, when the core wrap sheet described in Patent Literature 1 is used, the absorption performance of the absorbent body may deteriorate.
Further, in the absorbent body of Patent Document 1, although the liquid diffusibility in the longitudinal direction of the core wrap sheet of the lower layer is disclosed, the liquid diffusibility in the longitudinal direction of the core wrap sheet of the upper layer is not disclosed. . Therefore, in the absorbent body using the core wrap sheet of Patent Document 1, there is room for improvement in liquid diffusibility in the longitudinal direction. That is, even when body fluids are repeatedly discharged, the absorber can be used in a wide range to the vicinity of both ends in the longitudinal direction to absorb a large amount of discharged body fluids. There was room.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide an absorbent body having high absorption performance and excellent repeated absorption of body fluids.

The inventors of the present invention have conducted intensive research in view of the above problems. As a result, it has an absorbent core and a core wrap sheet, and the core wrap sheet is a nonwoven fabric in which water absorbent fibers are entangled with each other. The inventors have found that the above problems can be solved by an absorbent body in which the low-density portions are alternately arranged, and have completed the present invention.

Specifically, the present invention has an upper surface and a lower surface, a longitudinal direction, a width direction, and a thickness direction that are orthogonal to each other, and an absorbent core and an upper and lower portion of the absorbent core in the thickness direction. and a core wrap sheet provided on at least one side, wherein the absorbent core contains a superabsorbent polymer, and the core wrap sheet is a flat water absorbent nonwoven fabric in which water absorbent fibers are entangled with each other. The water-absorbent nonwoven fabric includes a plurality of high-density portions extending along the longitudinal direction and arranged side by side in the width direction, and a plurality of high-density portions extending along the longitudinal direction. and a plurality of low-density portions disposed between adjacent high-density portions.

ADVANTAGE OF THE INVENTION According to this invention, the absorption performance is high and it can provide the absorber excellent in repeated bodily fluid absorption.

1 is a plan development view of a tape-fastening type disposable diaper 1 having an absorbent body 17 according to an embodiment of the present invention. FIG. FIG. 2 is a cross-sectional view of the absorbent body 17 before body fluid absorption, taken along the plane W ₁ -W ₁ of FIG. 1; FIG. 2 is a cross-sectional view of the absorbent body 17 after absorbing body fluid, taken along the plane W ₁ -W ₁ of FIG. 1; Fig. 4 is an enlarged perspective view of a core wrap sheet 26 included in the absorbent body 17 according to the embodiment of the present invention;

<Aspect of the present invention>
The present invention relates to the aspects shown below.

[First aspect]
(Constitution)
A first aspect of the present invention has an upper surface and a lower surface, and mutually orthogonal longitudinal, width, and thickness directions, and includes an absorbent core and upper and lower portions of the absorbent core in the thickness direction. and a core wrap sheet provided on at least one side, wherein the absorbent core contains a superabsorbent polymer, and the core wrap sheet is a flat water absorbent nonwoven fabric in which water absorbent fibers are entangled with each other. The water-absorbent nonwoven fabric includes a plurality of high-density portions extending along the longitudinal direction and arranged side by side in the width direction, and a plurality of high-density portions extending along the longitudinal direction. and a plurality of low-density portions arranged between adjacent high-density portions.

(effect)
According to the first aspect of the present invention, at least one of the upper layer and the lower layer of the absorbent core is provided with a flat core wrap sheet formed by entangling water absorbent fibers. The core wrap sheet has a plurality of high-density portions of water-absorbing fibers and a plurality of low-density portions of water-absorbing fibers extending in the longitudinal direction.
Since the core wrap sheet is flat, an absorbent article using this absorbent body is less likely to have a gap between the core wrap sheet and the top sheet. Therefore, body fluids absorbed by the top sheet are easily transferred to the core wrap sheet and easily absorbed by the absorbent body.
In this case, since the core wrap sheet is a water-absorbent nonwoven fabric in which water-absorbent fibers are entangled, when wet, the entanglement between the fibers is loosened, and the water-absorbent fibers themselves tend to stretch when wet. Therefore, by allowing the core wrap sheet to absorb bodily fluids, the core wrap sheet can be stretched relatively easily, and the ability to follow the swelling of the superabsorbent polymer can be enhanced. In addition, the core wrap sheet has low density areas that tend to stretch when a load is applied. Therefore, even when the superabsorbent polymer swells, the core wrap sheet can be easily stretched, and the followability to the swelling of the superabsorbent polymer can be improved. They can enhance the absorbent performance of the superabsorbent polymer and thus of the absorbent body.
Furthermore, the core wrap sheet has a high-density portion, and the high-density portion easily diffuses the body fluid absorbed by the absorbent body in the longitudinal direction. Therefore, body fluid can be absorbed widely to the vicinity of both ends in the longitudinal direction of the absorbent body, and as a result, repeated absorbability is excellent when body fluid is repeatedly absorbed.

[Second aspect]
(Constitution)
A second aspect of the present invention is a laminated absorbent core in which a first absorbent core layer, an intermediate layer, and a second absorbent core layer are laminated in this order from the upper surface to the lower surface. is the absorbent body according to the first aspect.

(effect)
According to the second aspect of the present invention, in the intermediate layer sandwiched between the first absorbent core layer and the second absorbent core layer, it becomes easier for body fluids to pass through in the longitudinal direction and the width direction, and the absorber and the body fluids Since the contact area of the absorbent body can be increased, the body fluid repeated absorption of the absorbent body is excellent.

[Third aspect]
(Constitution)
A third aspect of the present invention is the absorbent body according to the second aspect, wherein the intermediate layer is a liquid-permeable nonwoven fabric having hydrophilicity and liquid permeability.

(effect)
According to the third aspect of the present invention, the intermediate layer is a liquid-permeable nonwoven fabric having hydrophilicity and liquid-permeability. The body is excellent in repeatedly absorbing bodily fluids.

[Fourth aspect]
(Constitution)
A fourth aspect of the present invention is the absorbent body according to the third aspect, wherein the liquid-permeable nonwoven fabric is an air-through nonwoven fabric composed of thermoplastic synthetic fibers.

(effect)
In general, an air-through nonwoven fabric made of thermoplastic synthetic fibers is bulky and has excellent cushioning properties. It is hard to be inhibited, and the absorber is excellent in repeated absorption of body fluids.

[Fifth aspect]
(Constitution)
In a fifth aspect of the present invention, the absorbent body extends in the longitudinal direction of the second absorbent core layer, and has a superabsorbent polymer nonexistent region in the thickness direction in which the superabsorbent polymer does not exist. The absorbent body according to any one of the second to fourth aspects, further comprising:

(effect)
According to the fifth aspect of the present invention, since the body fluid can be diffused in the longitudinal direction through the superabsorbent polymer-free region, the diffused body fluid can easily permeate the absorbent body, and the absorbent body can absorb the body fluid repeatedly. Excellent.

[Sixth aspect]
(Constitution)
In a sixth aspect of the present invention, the core wrap sheet includes a first core wrap sheet portion located above the center plane in the thickness direction of the absorber, and a first core wrap sheet portion located above the center plane in the thickness direction of the absorber. and a second core wrap sheet portion located on the lower side, wherein the core wrap sheet encloses the laminated absorbent core.

(effect)
According to the sixth aspect of the present invention, the core wrap sheet formed by entangling water absorbent fibers covers the entire absorbent core. Therefore, since the high-density portion can widely diffuse the body fluid in the longitudinal direction, the absorbent body is excellent in repetitive absorption of the body fluid. Moreover, even when the superabsorbent polymer swells, the low-density portion expands, thereby increasing the absorption performance of the superabsorbent polymer.

[Seventh aspect]
(Constitution)
In a seventh aspect of the present invention, the first core wrap sheet portion includes a central sheet portion arranged near the center in the width direction and a pair of outer sheet portions arranged on both outer sides in the width direction. , wherein the first core wrap sheet portion is a pair of overlapping portions in which the central sheet portion overlaps each of the pair of outer sheet portions in the thickness direction, and the longitudinal The absorbent article according to the sixth aspect above, comprising one extending in a direction.

(effect)
According to the seventh aspect of the present invention, the first core wrap sheet has a pair of overlapped portions in which the central sheet portion and the pair of outer sheet portions are overlapped in the thickness direction. Therefore, when body pressure is applied, the fiber density of the absorbent fibers in the pair of overlapping portions tends to be higher than the fiber density of the absorbent fibers in the portions other than the pair of overlapping portions. Along the , it becomes easier to spread body fluids. As a result, the absorber is excellent in repeated diffusion of bodily fluids.

[Eighth aspect]
(Constitution)
In an eighth aspect of the present invention, the dimension in the width direction of the first absorbent core layer is smaller than the dimension in the width direction of the second absorbent core layer, and the first absorbent core layer is: The absorber according to the seventh aspect, arranged in the widthwise intermediate portion.

(effect)
According to the eighth aspect of the present invention, the widthwise dimension of the first absorbent core layer is smaller than the widthwise dimension of the second absorbent core layer, and the first absorbent core layer is disposed in the widthwise intermediate portion of the absorbent body. ing. Therefore, even when the body fluid becomes difficult to be absorbed by the first absorbent core layer, it can reach the wide surface of the second absorbent core layer along the surface of the first absorbent core layer in the width direction. That is, body fluids not absorbed by the first absorbent core layer can be absorbed by the second absorbent core layer. As a result, the absorbent body can be used more effectively, and the absorbent body is excellent in repetitive absorption of bodily fluids.

[Ninth aspect]
(Constitution)
In a ninth aspect of the present invention, the absorbent body is divided into widthwise both end portions disposed at both widthwise end portions and a widthwise intermediate portion sandwiched between the widthwise both end portions, and the pair of overlapping portions is the absorber according to the eighth aspect, which is arranged at both ends in the width direction.

(effect)
According to the ninth aspect of the present invention, the pair of overlapping portions are provided at both ends in the width direction of the absorber. Therefore, since the superabsorbent polymer originating from the first absorbent core layer does not exist in the pair of overlapped portions, body fluids diffuse through the paired overlapped portions in the longitudinal direction and permeate the second absorbent core layer. easier. As a result, the absorber has excellent repetitive absorption of body fluids.

[Tenth Aspect]
(Constitution)
A tenth aspect of the present invention is the absorbent body according to any one of the seventh to ninth aspects, wherein the high-density portions are arranged at both ends of the core wrap sheet in the width direction.

(effect)
According to the tenth aspect of the present invention, since the high-density portions with high liquid permeability along the longitudinal direction are arranged at both ends in the width direction of the core wrap sheet, the water-absorbent fibers of the pair of overlapping portions The fiber density of the absorbent body is higher, the liquid diffusibility in the pair of overlapping portions can be made more excellent, and the body fluid repeated absorption of the absorbent body is excellent.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan development view of a tape-fastening type disposable diaper ₁ (hereinafter also simply referred to as "disposable diaper") provided with an absorbent body 17 according to the present embodiment, and FIG. ₁ is a cross-sectional view of the absorbent body 17 before absorbing body fluid, and FIG. 3 is a cross-sectional view of the absorbent body 17 after absorbing body fluid, taken along the W ₁ -W ₁ plane of FIG. 1 and 2, the absorbent body 17 of this embodiment has an upper surface 34 and a lower surface 35, and has a longitudinal direction L, a width direction W, and a thickness direction T that are orthogonal to each other, Along the width direction W, it is divided into width direction both end portions E and width direction middle portion C. As shown in FIG. Here, the widthwise intermediate portion C refers to a region extending about 70% in the widthwise direction W centered on the central point in the widthwise direction W at the portion having the maximum dimension in the widthwise direction W, Approximately 15% of each area is defined as both width direction end portions E. FIG. Also, the longitudinal direction L, width direction W, and thickness direction T of the disposable diaper 1 shall coincide with the longitudinal direction L, width direction W, and thickness direction T of the absorbent body 17 . The "absorbent article" of the present invention is not limited to a tape-type disposable diaper, and may be, for example, a pants-type disposable diaper, an incontinence pad, a light incontinence pad, a sanitary pad, a panty liner, or the like.

As shown in FIG. 1, the disposable diaper 1 includes a liquid-permeable topsheet 3, a liquid-impermeable backsheet 5, and an absorbent body of the present embodiment disposed between the topsheet 3 and the backsheet 5. 17, and further includes a leak-proof wall 7 having an elastic member 9, a tape fastener 15, and the like. Further, in this embodiment, the absorbent body 17 is placed on the top sheet 3 and the back sheet so that the upper surface 34 is positioned on the top sheet 3 side of the disposable diaper 1 and the lower surface 35 is positioned on the back sheet 5 side of the disposable diaper 1 . 5, in the present invention, the upper surface of the absorbent body may be arranged on the back sheet side of the absorbent article, and the lower surface of the absorbent body may be arranged on the top sheet side of the absorbent article.

<Absorber>
As shown in FIG. 2, the absorbent body 17 of the present embodiment includes an absorbent core 21 and core wrap sheets 26 provided above and below the absorbent core 21 in the thickness direction T so as to enclose the absorbent core 21. and have The absorbent core 21 contains a superabsorbent polymer, and the core wrap sheet 26 is a flat water-absorbent nonwoven fabric in which water-absorbent fibers are entangled with each other. A plurality of high-density portions 32 extending along the width direction L and arranged side by side in the width direction W, and a plurality of high-density portions 32 extending along the longitudinal direction L and adjacent to each other among the plurality of high-density portions 32. and a plurality of low density portions 33 disposed therebetween. In addition, in the present invention, the core wrap sheet does not have to be configured to enclose the absorbent core, and may be provided above or below the absorbent core in the thickness direction.

Since the core wrap sheet 26 is flat, in the disposable diaper 1 using this absorbent body 17 , a gap is less likely to occur between the core wrap sheet 26 and the top sheet 3 . Therefore, the body fluid absorbed by the top sheet 3 is easily transferred to the core wrap sheet 26 and then absorbed by the absorbent body 17 .
At this time, since the core wrap sheet 26 is a water-absorbent nonwoven fabric in which water-absorbent fibers are entangled, when wet, the entanglement between the water-absorbent fibers is loosened and the water-absorbent fibers themselves are easily stretched by wetting. Therefore, as shown in FIG. 3, by allowing the core wrap sheet 26 to absorb bodily fluids, the core wrap sheet 26 can be stretched relatively easily, and the ability to follow the swelling of the superabsorbent polymer can be enhanced. . Furthermore, as shown in FIG. 4, the core wrap sheet 26 has a low density portion 33, which tends to stretch when a load is applied. Therefore, even when the superabsorbent polymer swells, the core wrap sheet 26 can be easily stretched as shown in FIG. 3, and the followability to the swelling of the superabsorbent polymer can be improved. They can enhance the absorbent performance of the superabsorbent polymer and thus the absorbent body 17 .
Furthermore, the core wrap sheet 26 has a high-density portion 32, and the high-density portion 32 facilitates diffusion in the longitudinal direction L of body fluid absorbed by the absorbent body 17. As shown in FIG. Therefore, body fluid can be absorbed widely to the vicinity of both ends in the longitudinal direction of the absorbent body 17, and as a result, repeated absorption of body fluid is excellent.

The absorbent body of the present invention preferably has a thickness of 0.8 mm or more and 3 mm or less.

[Absorptive core]
The absorbent core 21 included in the absorbent body 17 of the present embodiment is arranged between the top sheet 3 and the back sheet 5 together with the core wrap sheet 26 in the disposable diaper 1 . The absorbent core 21 included in the absorbent body 17 of the present embodiment has a substantially rectangular planar shape in which the dimension in the longitudinal direction L is longer than the dimension in the width direction W, and the dimension in the thickness direction T is constant. have. However, the planar shape of the absorbent core provided in the absorbent body of the present invention is not limited to a substantially rectangular planar shape, and any planar shape can be used as long as the function of the absorbent core to absorb and retain liquid is not impaired. shape can be adopted.

In this embodiment, the absorbent core 21 contains superabsorbent polymer, but in the present invention, the absorbent core preferably contains pulp fibers as needed. The basis weight of the superabsorbent polymer in the absorbent body of the present invention is preferably 50 g/m ² or more and 500 g/m ² or less, and the basis weight of the pulp fibers is 0 g/m ² or more and 1000 g/m ² or less. is preferred. Moreover, the ratio of the basis weight of the superabsorbent polymer contained in the absorbent body of the present invention to the basis weight of the pulp fibers is preferably from 1:6 to 6:0.

In this embodiment, the absorbent core 21 has a first absorbent core layer 18, an intermediate layer 19, and a second absorbent core layer 20 laminated in this order from the upper surface 34 to the lower surface 35 with an adhesive interposed therebetween. laminated absorbent core. However, in the present invention, the absorbent core is not limited to the laminated absorbent core described above, and may be composed of a single, substantially uniform superabsorbent polymer layer. Moreover, in the present invention, a hot-melt adhesive and the like can be mentioned as the adhesive used as necessary.

(First absorbent core layer)
In this embodiment, the first absorbent core layer 18 is a layer of superabsorbent polymer arranged on the upper surface 34 side of the intermediate layer 19, and a certain amount of superabsorbent polymer is attached to the intermediate layer via an adhesive. 19. The first absorbent core layer 18 is sandwiched between the intermediate layer 19 and the core wrap sheet 26 . In the first absorbent core layer 18, the superabsorbent polymers are arranged substantially uniformly in the planar direction, but in the first absorbent core layer of the present invention, the superabsorbent polymers are arranged substantially uniformly in the planar direction. It does not have to be. In the present invention, the basis weight of the superabsorbent polymer in the first absorbent core layer is preferably 25 g/m ² or more and 250 g/m ² or less. By setting the basis weight of the absorbent polymer within the above range, the absorbent body of the present invention can sufficiently absorb bodily fluids contained in excrement, and blocking caused by the swollen superabsorbent polymer can be prevented to some extent. can be suppressed. In the present invention, the first absorbent core layer may contain pulp fibers, and the basis weight of the pulp fibers in that case is preferably more than 0 g/m ² and not more than 500 g/m ² . By including pulp fibers in the first absorbent core layer, the absorption rate of the absorbent body can be increased. On the other hand, when the pulp fibers are not contained, the absorber can be made thin. In the present invention, the ratio of the basis weight of the superabsorbent polymer to the basis weight of the pulp fibers in the first absorbent core layer is preferably from 1:6 to 6:0.

In this embodiment, the dimension in the width direction W of the first absorbent core layer 18 is smaller than the dimension in the width direction W of the second absorbent core layer 20 described later over the entire length in the longitudinal direction L. . As shown in FIG. 2, the first absorbent core layer 18 is arranged so that the center line of the first absorbent core layer 18 in the width direction W overlaps the center line of the absorbent body 17 in the width direction W. Both ends in the width direction W of the first absorbent core layer 18 are positioned closer to the center in the width direction W than the respective ends in the width direction W of the second absorbent core layer 20 . By adopting such a configuration, even when the body fluid is difficult to be absorbed by the first absorbent core layer 18, the body fluid spreads along the surface of the first absorbent core layer 18 in the width direction W, and the width is widened. The surface of the second absorbent core layer 20 can be reached. That is, body fluid that has not been absorbed by the first absorbent core layer 18 can be absorbed by the second absorbent core layer 20, and the absorbent body 17 can absorb body fluid even when the body fluid is repeatedly discharged. Absorbs body fluids stably and has excellent repetitive absorption of body fluids. In the present invention, the widthwise dimension of the first absorbent core layer may be the same as the widthwise dimension of the second absorbent core layer, or may be larger than the widthwise dimension of the second absorbent core layer. good.

In the present invention, the "width dimension of the first absorbent core layer" and the "width dimension of the second absorbent core layer" refer to the width of the first absorbent core layer and the second absorbent core layer. It is defined to mean the maximum length of the region bounded by the outermost edges of the direction.

(super absorbent polymer)
In the present invention, the superabsorbent polymer is intended to absorb and retain liquid in excrement in the absorbent body, and the type is not limited as long as the purpose can be achieved. More specifically, the superabsorbent polymer includes polyaspartate-based polymer, sodium polyacrylate-based polymer, isobutylene-maleic anhydride copolymer, starch-acrylic acid graft copolymer, acrylic acid- A vinyl alcohol copolymer etc. can be mentioned.

Here, in the present invention, among the above polymers and copolymers, it is preferable to use superabsorbent polymers that are granules of polymers or copolymers obtained by reverse phase suspension polymerization. The superabsorbent polymer, which is a granule of a polymer or copolymer obtained by reversed-phase suspension polymerization, is a water-in-oil emulsion of a composition containing a polymerizable monomer in the presence of a surfactant or emulsifier. It is a polymer or copolymer granule obtained by carrying out a polymerization reaction. Such superabsorbent polymer granules have a larger surface area than spherical superabsorbent polymers having the same volume. The absorption speed of the soluble polymer is increased. Examples of such superabsorbent polymers include those obtained by the production method described in JP-A-57-094011.

(middle layer)
As described above, the absorbent core 21 in the absorbent body 17 of the present embodiment is a laminated absorbent core in which the intermediate layer 19 is interposed between the first absorbent core layer 18 and the second absorbent core layer 20. be. By adopting such a configuration, it becomes easier for body fluids to pass through in the longitudinal direction L and the width direction W in the intermediate layer 19 sandwiched between the first absorbent core layer 18 and the second absorbent core layer 20, Since the contact area between the absorbent body 17 and the body fluid can be increased, the absorbent body 17 is excellent in repetitive absorption of body fluid. In addition, as will be described later, in the present embodiment, the absorber 17 has joints 29 at both ends E in the width direction, where the first core wrap sheet portion 24 and the intermediate layer 19 are joined. is doing. However, in the present invention, the absorbent core is not limited to having an intermediate layer. In the present invention, the intermediate layer is preferably a liquid-permeable nonwoven fabric having hydrophilicity and liquid permeability, and the liquid-permeable nonwoven fabric is preferably an air-through nonwoven fabric composed of thermoplastic synthetic fibers. . Since the intermediate layer is a liquid-permeable nonwoven fabric, the liquid-permeability can be ensured even when the absorbent body absorbs water. In general, an air-through nonwoven fabric made of thermoplastic synthetic fibers is bulky and has excellent cushioning properties. And even when the second absorbent core layer swells, the diffusibility of body fluids in the intermediate layer is less likely to be inhibited, and the absorbent body is excellent in repeated absorption of body fluids. In particular, since the above air-through nonwoven fabric is composed of a nonwoven fabric in which the fibers are heat-sealed, it has a certain resistance to external loads, and the superabsorbent polymer contained in the absorbent body absorbs water and swells. Even in this case, it is possible to effectively prevent the absorber from losing its shape.

In the present invention, as the thermoplastic synthetic fibers constituting the air-through nonwoven fabric, it is preferable to employ core-sheath type conjugate fibers using a thermoplastic resin as at least the sheath component constituting the fiber surface. By adopting a thermoplastic resin as the sheath component that constitutes the fiber surface, the fiber exhibits heat-sealing properties, so the resin component used as the core component can be appropriately selected according to the desired physical properties of the intermediate layer. . For example, as the above-mentioned core-sheath type conjugate fiber, by using a conjugate fiber using a relatively strong resin component as a core component that does not constitute the fiber surface, it has a stronger resistance to tensile stress etc. An intermediate layer can be provided. Examples of resins that can be used as the core component and the sheath component include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, and ionomer resin. polyolefins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polylactic acid, and the like; polyamides such as nylon, and the like. In the present embodiment, it is preferable to use a polyolefin resin such as polyethylene or polypropylene as the sheath component for the purpose of achieving both thermal adhesiveness and tensile strength, and the above polyolefin resin or polyethylene terephthalate as the core component. It is preferable to use a polyester-based resin such as

In the present invention, the intermediate layer preferably has a basis weight of 9 g/m ² or more and 100 g/m ² or less, more preferably 12 g/m ² or more and 60 g/m ² or less. In the present invention, the thickness of the intermediate layer is preferably 0.1 mm or more and 5 mm or less, more preferably 0.15 mm or more and 3 mm or less. Furthermore, in the present invention, the intermediate layer preferably has a bending resistance of 60 mm or more and 160 mm or less in the MD direction as measured by a cantilever method, which will be described later. In addition, the intermediate layer preferably has a 30% tensile strength in the CD direction of 0.3 N/25 mm or more and 6 N/25 mm or less. By setting the basis weight, thickness, bending resistance, and tensile strength of the intermediate layer within the above ranges, the intermediate layer can ensure liquid permeability even after the superabsorbent polymer absorbs water, The shape of the body can be well maintained, and the loss of shape of the absorbent body can be effectively prevented.

In the present embodiment, the intermediate layer 19 is required to have relatively high physical strength, and therefore, the intermediate layer 19 is not formed with three-dimensional unevenness by gear processing or embossing, which will be described later. By using the intermediate layer 19 without gearing or embossing, the resistance to external loads such as tensile stress can be enhanced. However, in the present invention, as long as the tensile properties of the intermediate layer are not impaired, the intermediate layer may be formed with unevenness to increase the apparent bulkiness of the intermediate layer or to enhance the retention performance of the superabsorbent polymer. good.

(Second absorbent core layer)
The absorbent core 21 included in the absorbent body 17 of this embodiment has a second absorbent core layer 20 in a form held on the lower surface 35 side of the intermediate layer 19, and the second absorbent core layer 20 is , intermediate layer 19 and core wrap sheet 26 . The configuration of the second absorbent core layer 20 is basically the same as that of the first absorbent core layer 18, except for the points specifically described below. In the present invention, the second absorbent core layer contains a superabsorbent polymer and, if necessary, pulp fibers. may be the same as these basis weights in the first absorbent core layer, may be larger than these basis weights in the first absorbent core layer, or may be smaller than these basis weights in the first absorbent core layer.

As shown in FIG. 2, in this embodiment, the second absorbent core layer 20 includes two superabsorbent polymer nonwoven fabrics extending in the longitudinal direction L and having no superabsorbent polymer in the thickness direction T. A presence area 28 is provided. Here, the superabsorbent polymer tends to swell when it absorbs water, and becomes less permeable to liquid due to blocking. Since the second absorbent core layer 20 has the superabsorbent polymer non-existing region 28, the body fluid can diffuse in the longitudinal direction L through the superabsorbent polymer nonexisting region 28, so that the diffused body fluid can be absorbed. It becomes easy to permeate the body 17, and the absorbent body 17 is excellent in repeated bodily fluid absorption. In particular, in the present embodiment, the second absorbent core layer 20 is located closer to the clothing side than the intermediate layer 19, so that the absorbent body 17 can easily absorb body fluids remaining on the clothing side of the absorbent body 17. . In the present invention, even when the second absorbent core layer having the superabsorbent polymer non-existing region is positioned closer to the skin than the intermediate layer, the presence of the superabsorbent polymer nonexistent region will cause the skin to absorb moisture. It is expected that permeation of body fluids from the side to the side of the clothes will be promoted.

In the present invention, the number of superabsorbent polymer nonexistent regions in the second absorbent core layer is not limited to two, and blocking can be effectively prevented while maintaining the absorbent performance of the absorbent. From the viewpoint of doing so, it is preferably 1 or more and 4 or less, preferably 2 or 3, with respect to the entire width in the width direction of the second absorbent core layer. In the present invention, when there are three or more superabsorbent polymer nonexistent regions extending in the longitudinal direction, these superabsorbent polymer nonexistent regions are centered on the center line in the width direction, and the second absorbent core It is preferable that the layers are provided at regular intervals, and the width thereof is preferably 5 mm or more and 60 mm or less.

In addition, in the absorbent body of the present invention, the superabsorbent polymer-free region may exist in the first absorbent core layer in addition to the second absorbent core layer. In this case, the number of superabsorbent polymer nonexistent regions in the first absorbent core layer may be at least greater than the number of superabsorbent polymer nonexistent regions in the second absorbent core layer. The number may be the same as the number of superabsorbent polymer nonexistent regions in the absorbent core layer. In addition, the site where the superabsorbent polymer non-existing region in the first absorbent core layer and the site where the superabsorbent polymer nonexistent region in the second absorbent core layer are located overlap each other in the width direction W. may be different from each other.

In the present invention, when the first absorbent core layer and/or the second absorbent core layer has a superabsorbent polymer absent region, the first absorbent core layer and/or the second absorbent core layer The dimension in the width direction means the dimension in the width direction of the region including the superabsorbent polymer-free region.

[Core wrap sheet]
FIG. 4 is an enlarged perspective view of the core wrap sheet 26 included in the absorber 17 of this embodiment. As described above, the core wrap sheet 26 in this embodiment is provided above and below the absorbent core 21 in the thickness direction T so as to enclose the absorbent core 21 . The core wrap sheet 26 is a flat water-absorbent nonwoven fabric in which water-absorbent fibers are entangled with each other, and as shown in FIG. and a plurality of low-density portions 33 extending along the longitudinal direction L and arranged between adjacent high-density portions 32 among the plurality of high-density portions 32. and have The core wrap sheet 26 included in the absorber 17 of this embodiment is flat. In the disposable diaper 1 using the absorbent body 17 having such a flat core wrap sheet 26 , a gap is less likely to occur between the core wrap sheet 26 and the top sheet 3 . Therefore, body fluid absorbed by the top sheet 3 is easily transferred to the core wrap sheet 26 and easily absorbed by the absorbent body 17 . As shown in FIG. 4, in the present embodiment, the core wrap sheet 26 has unevenness that is repeatedly present in a part of the area, but the height difference between the concave and convex portions on one surface of the core wrap sheet 26 is large. t is about 1 times the thickness d of the core wrap sheet 26 in the thickness direction T. In the present invention, when the core wrap sheet is “flat”, it means that the core wrap sheet does not substantially have repeated unevenness, or even if the core wrap sheet has repeated unevenness, the core wrap sheet is flat. It refers to a state in which the height difference between the recesses and protrusions on one surface is 3 times or less, preferably 2.5 times or less, more preferably 1.2 times or less, the thickness of the core wrap sheet in the thickness direction. In the present invention, the core wrap sheet may be composed of one sheet of nonwoven fabric, or may be composed of a plurality of nonwoven fabrics bonded together, and may be composed of at least upper and lower portions of the absorbent core in the thickness direction. It suffices if it is provided on one side.

In this embodiment, as shown in FIG. 3, even when the absorbent body 17 absorbs bodily fluids and the superabsorbent polymer swells toward the upper surface 34 and the lower surface 35, the core wrap sheet 26 resists swelling. Therefore, the absorption performance of the superabsorbent polymer and the absorbent body 17 can be enhanced.

Furthermore, the high-density portion 32 of the core wrap sheet 26 in the present embodiment facilitates diffusion in the longitudinal direction L of the body fluid absorbed by the absorbent body 17 . Therefore, body fluid can be absorbed widely to the vicinity of both ends in the longitudinal direction of the absorbent body 17, and as a result, repeated absorption of body fluid is excellent.

In the present invention, in the water-absorbing nonwoven fabric in which water-absorbing fibers are entangled, the entanglement between the fibers is loosened by wetting, and the water-absorbing fibers themselves tend to stretch when wet. The sheet can be stretched relatively easily. Furthermore, since the low-density portion of the core wrap sheet is easily elongated when a load is applied, the core wrap sheet can be easily elongated even when the superabsorbent polymer is swollen.

(High density part and low density part)
As shown in FIG. 4 , in the present embodiment, the core wrap sheet 26 extends along the longitudinal direction L and includes a plurality of high-density portions 32 arranged side by side in the width direction W, and and a plurality of low-density portions 33 arranged between adjacent high-density portions 32 of the plurality of high-density portions 32, and extending along the width direction W of the core wrap sheet 26. A high-density portion 32 is arranged in the portion. In the present invention, the widthwise distance between adjacent high-density portions is preferably 0.1 mm or more and 1 mm or less, and the widthwise distance between adjacent low-density portions is preferably 0.3 mm or more and 4 mm or less. is preferred. When each adjacent low-density portion and high-density portion are regarded as one unit, the distance between repeating units is preferably 0.4 mm or more and 5 mm or less. In the present invention, when the high-density portions are arranged at both ends in the width direction of the core wrap sheet, the dimension in the width direction of the high-density portions located at both ends in the width direction is 3 mm or more and 20 mm or less. preferable.

In the present invention, the water-absorbent fibers located in the high-density portion are oriented along the longitudinal direction, and the water-absorbent fibers located in the low-density portion are more oriented than the fibers located in the high-density portion. preferably low. As a result, body fluids can be easily diffused in the longitudinal direction in the high-density portion where the water-absorbent fibers have a high density, and the low-density portion can be easily stretched in the width direction.

(water absorbent nonwoven fabric)
In the absorbent body of the present invention, the water-absorbing fibers forming the core wrap sheet are preferably regenerated cellulose fibers, more preferably rayon fibers. Regenerated cellulose fibers such as rayon fibers are superior to pulp fibers in fiber uniformity (fiber length, fiber diameter, etc.), so the core wrap sheet has better extensibility when wet, and the absorbent body The absorption performance of the superabsorbent polymer in is excellent. On the other hand, a water-absorbent nonwoven fabric formed by entangling regenerated cellulose fibers such as rayon fibers is subject to stress when a load is applied from the outside of the absorbent body or when it is to be stretched by a certain amount of displacement or more. Since a relatively high tensile tension acts, it is possible to improve the wet shape retention of the absorbent, which is a property that the absorbent does not easily lose its shape even when wet.

Further, in the absorbent body of the present invention, the water-absorbent nonwoven fabric constituting the core wrap sheet is preferably a spunlace nonwoven fabric composed of water-absorbent fibers, and a spunlace nonwoven fabric composed of regenerated cellulose fibers (e.g., rayon fibers). More preferably, it is a lace nonwoven fabric. Here, as a spunlaced nonwoven fabric that can be used as a core wrap sheet, a spunlaced nonwoven fabric in which the fibers constituting the nonwoven fabric are mainly rayon can be mentioned. It is preferably a spunlaced nonwoven fabric in which at least 85% by mass of the fibers is rayon, more preferably a spunlaced nonwoven fabric in which at least 90% by mass is rayon, and is a spunlaced nonwoven fabric consisting essentially of rayon. is more preferred.

In the present invention, any hydrophilic fiber can be mentioned as the fiber component other than the regenerated cellulose fiber constituting the spunlaced nonwoven fabric. For example, the spunlaced nonwoven may be a spunlaced nonwoven comprising rayon fibers and pulp fibers. Such a spunlaced nonwoven fabric containing rayon fibers and pulp fibers includes an upper layer of 80% or more and 100% or less of rayon fibers, an intermediate layer of 80% or more and 100% or less of pulp fibers, and a layer of 80% or more and 100% or less of rayon fibers. Mention may be made of spunlaced nonwovens consisting of a sublayer. The core wrap sheet in the present invention preferably has a basis weight of 15 g/m ² or more and 200 g/m ² or less, more preferably 25 g/m ² or more and 150 g/m ² or less, and a thickness d of 0.2 g/m 2 or more and 150 g/m 2 or less. It is preferably 1 mm or more and 2 mm or less, more preferably 0.2 mm or more and 1.5 mm or less. By setting the basis weight and thickness of the core wrap sheet within the above ranges, it is possible to achieve both elongation properties and strength of the core wrap sheet.

(First core wrap sheet portion and second core wrap sheet portion)
In the present embodiment, the core wrap sheet 26 is a surface parallel to the width direction W and the longitudinal direction L, passing through the center of the thickness direction T at the portion where the absorber 17 has the maximum dimension in the thickness direction T. A first core wrap sheet portion 24 located above the thickness direction center plane Tc of the absorber 17 and a second core wrap sheet portion located below the thickness direction center plane Tc of the absorber 17 25 and The core wrap sheet 26 wraps around the laminated absorbent core in the width direction W, thereby enclosing the laminated absorbent core. According to the present embodiment, the high-density portion 32 described above can widely diffuse body fluid in the longitudinal direction, so that the absorbent body 17 is excellent in repetitive absorption of body fluid. Moreover, even when the superabsorbent polymer swells, the absorption performance of the superabsorbent polymer is enhanced by the expansion of the low-density portion 33 described above.

In the present invention, the first core wrap sheet portion and the second core wrap sheet portion may be separated separate sheets, and refer to different portions of a single sheet that is not separated. good too. When the first core wrap sheet portion and the second core wrap sheet portion each form a separate single sheet, the first core wrap sheet portion and the second core wrap sheet portion are: Both ends in the width direction may be joined along the longitudinal direction. Moreover, as will be described later, the first core wrap sheet portion and the second core wrap sheet portion may be in a state in which at least portions of a plurality of sheets are joined.

(Central sheet portion and outer sheet portion)
In this embodiment, the first core wrap sheet portion 24 includes a central sheet portion 22 arranged near the center in the width direction W and a pair of outer sheet portions 23 arranged on both outer sides in the width direction W. I have. Both ends of the central sheet portion 22 in the width direction W are overlapped with the ends of the pair of outer sheet portions 23 in the width direction W near the central sheet portion 22 in the thickness direction T. A pair of overlapping portions 27 extending in L are overlapped. By providing the first core wrap sheet portion 24 with the above configuration, the fiber density of the water-absorbing fibers in the pair of overlapping portions 27 can be increased, and in the pair of overlapping portions 27, body fluids can be absorbed along the longitudinal direction L. can be more easily diffused. As a result, the absorber 17 is excellent in repeated diffusion of bodily fluids. As shown in FIG. 2, in the present embodiment, the outer sheet portion 23 and the central sheet portion 22 each constitute at least a part of different core wrap sheets separated from each other, and the central sheet portion 22 is one sheet. The second core wrap sheet portion 25 and the pair of outer sheet portions 23 are integrated to form another sheet.

In this embodiment, as shown in FIG. 3, in each of the pair of overlapping portions 27, each of the pair of outer sheet portions 23 is arranged closer to the upper surface 34 than the central sheet portion 22, and the pair of An edge 31 of each of the outer sheet portions 23 on the side of the central sheet portion 22 is spaced from the central sheet portion 22 . By adopting such a configuration, as shown in FIG. 3, when the widthwise intermediate portion C of the laminated absorbent core absorbs bodily fluids and swells, the upper surface 34 of the absorbent body 17 inclines, and the central sheet portion The edge 31 of the outer sheet portion 23 superimposed on 22 is lifted from the surface of the central sheet portion 22, and the edge 31 of the outer sheet portion 23 can function as a leak prevention wall.

In this embodiment, as described above, the dimension in the width direction W of the first absorbent core layer 18 is smaller than the dimension in the width direction W of the second absorbent core layer 20. The overlapping portions 27 are arranged at both ends E in the width direction. By adopting such a configuration, the superabsorbent polymer derived from the first absorbent core layer 18 does not exist in the region where the pair of overlapped portions 27 exist, so that body fluids can flow through the pair of overlapped portions 27 longitudinally. While diffusing in the direction L, it becomes easier to permeate the second absorbent core layer 20, and the absorbent body 17 has excellent repetitive absorption of body fluids.

In the present invention, high-density portions may be arranged at both ends of the core wrap sheet in the width direction. For example, it is preferable that the high density portions are arranged at both widthwise end portions of the sheet including the central sheet portion, and the high density portions are arranged at both widthwise end portions of the sheet including the outer sheet portions. By adopting such a configuration, the fiber density of the water-absorbent fibers in the pair of overlapping portions is increased, the liquid permeability along the longitudinal direction is further improved, and the liquid diffusion property in the pair of overlapping portions is improved. It can be made more excellent, and the body fluid repeated absorbability of the absorbent body is excellent.

(joints and intermediate joints)
As shown in FIG. 2 , in the present embodiment, at both ends E in the width direction, the absorbent body 17 has joints 29 where the first core wrap sheet portion 24 and the intermediate layer 19 are joined. is doing. By providing the joints 29 at both ends E in the width direction, as shown in FIG. 3, the core wrap sheet 26 is supported by the intermediate layer 19 having high resistance to tensile stress even when the absorbent body 17 absorbs water. Therefore, the shape retention property of the absorbent body 17 when wet is improved. In addition, in the present embodiment, the second absorbent core layer 20 has the superabsorbent polymer non-existing region 28, but the absorbent body 17 has a second It has an intermediate joint portion 30 where the core wrap sheet 26 and the intermediate layer 19 are joined. As a result, the absorber 17 has good shape retention when wet. However, in the present invention, the joint portion may be formed by joining the second core wrap sheet portion and the intermediate layer, and the intermediate joint portion may be formed by joining the first core wrap sheet portion and the intermediate layer. and may be formed by joining.

<Method for manufacturing absorber>
In manufacturing the absorbent body of the present invention, basically, it may be manufactured by a conventional method for manufacturing an absorbent body.

The absorbent core of the present invention is formed by laminating a first absorbent core layer, an intermediate layer, and a second absorbent core layer in this order from the upper surface side to the lower surface side. When it has a structure wrapped with a core wrap sheet, it can be manufactured by the manufacturing method shown below.
First, a hot-melt adhesive is applied onto the continuous sheet for the core wrap sheet as the lower layer while moving the continuous sheet for the core wrap sheet as the lower layer in the longitudinal direction L. Next, the superabsorbent polymer is applied from the superabsorbent polymer feeder to the continuous sheet for the lower layer core wrap sheet coated with the hot melt adhesive along the longitudinal direction L on both end portions and the central portion in the width direction W. to disperse. A continuous sheet for the intermediate layer 19, coated on both sides with a hot melt adhesive, is then laminated onto the underlying superabsorbent polymer for the core wrap sheet. Next, while moving the laminate in the longitudinal direction L, a superabsorbent polymer is supplied from another superabsorbent polymer supply device to both ends in the width direction W of the continuous sheet for the intermediate layer 19 coated with the hot melt adhesive. Sprinkle along the longitudinal direction L over the part and the central part. Next, a continuous sheet for the upper layer core wrap sheet coated with a hot melt adhesive is placed on the superabsorbent polymer on the continuous sheet for the lower layer core wrap sheet, with the hot melt adhesive on the superabsorbent polymer side. lamination. Then, after each side portion in the width direction W of the continuous sheet for the core wrap sheet of the lower layer is folded back onto the continuous sheet for the core wrap sheet of the upper layer, the laminate is passed through a pair of press rolls and pressed. By adjusting the thickness, the absorber 17 is formed.

Further, in the present invention, the high-density portion and the low-density portion of the water-absorbent nonwoven fabric are preferably formed by applying gear processing to the nonwoven fabric formed by hydroentangling. This gear processing has a plurality of ridges provided parallel to each other at regular intervals in the roll width direction along the outer peripheral surface, and concave grooves between adjacent ridges. The ridges are formed by inserting and stretching the original sheet between a forming device equipped with a pair of upper and lower stretching rolls configured to mesh with the concave grooves of the other stretching roll. . Here, in a state in which the portion sandwiched between the top of the ridge and the bottom of the groove is fixed, the portion positioned between the two adjacent and fixed portions is stretched. A portion fixed to the top portion and the bottom portion of the groove becomes a high-density portion, and a portion sandwiched between the adjacent high-density portions becomes a low-density portion. In general, when a nonwoven fabric having a particularly high bending resistance is subjected to gear processing, irregularities remain on the surface of the nonwoven fabric, and the nonwoven fabric may not be flat. In the present invention, by adjusting the basis weight and thickness of the nonwoven fabric constituting the core wrap sheet, the material of the water-absorbent fiber, etc., the bending resistance of the core wrap sheet is adjusted, and even if gear processing is performed, the core wrap sheet is preferably adjusted to be flat.

When manufacturing the disposable diaper 1 using the absorbent body 17 of this embodiment, the upper surface 34 is arranged on the side of the skin and the lower surface 35 is arranged on the side of the clothes. However, the absorbent article comprising the absorbent body of the present invention may be configured such that the upper surface of the absorbent body is placed on the side of the garment and the lower surface of the absorbent body is placed on the side of the skin, and the absorbent nonwoven fabric is composed of the absorbent core and the top sheet. or between the absorbent core and the backsheet.

The present invention will be described in detail below with reference to examples. It should be noted that the present invention is by no means limited to the examples shown below.

[Intermediate layer A]
An air-through nonwoven fabric having a basis weight of 40 g/m ² and a thickness of 0.8 mm (fineness 4.4 dtex × fiber length 51 mm , Unicharm Kokko Non-Woven Co., Ltd.) was prepared and used as the intermediate layer A. The intermediate layer A was not subjected to so-called gear processing, embossing, or the like, and was flat.

[Core Wrap Sheet A (“Core Wrap A”)]
A rayon spunlaced nonwoven fabric (rayon 100% by mass, fineness 1.7 dtex x fiber length 40 mm, manufactured by South Pacific Viscose Co., Ltd.) having a basis weight of 43 g/m ² and a thickness of 0.4 mm was prepared, and this nonwoven fabric was A plurality of high-density portions extending in the longitudinal direction and arranged side by side in the width direction by subjecting the raw fabric to gear processing, and between the adjacent high-density portions among the plurality of high-density portions. A flat core wrap sheet A was made having a low density portion located at . At both ends of the core wrap sheet A in the width direction, high-density portions were arranged. The width of the high density portion was about 0.2 mm, and the width of the low density portion was about 0.5 mm, except for both ends in the width direction.

[Core wrap sheet B (“core wrap B”)]
A spunlace nonwoven fabric having a basis weight of 45 g/m ² and a thickness of 0.4 mm (an upper layer of 100% rayon fiber of 1.7 dtex × 41 mm manufactured by South Pacific Viscose Co., Ltd. (basis weight of 11 g/m ² ), An intermediate layer of 100% pulp fiber from International Paper (basis weight 23 g/m ² ) and a lower layer of 100% rayon fiber of 1.7 dtex x 41 mm from South Pacific Viscose (basis weight 11 g/m 2 ). ² ) A spunlace nonwoven fabric consisting of ) is produced, and gear processing is applied to the raw fabric of this nonwoven fabric, and a plurality of high-density portions extending along the longitudinal direction and arranged side by side in the width direction. , a flat core wrap sheet B having a plurality of high density portions and low density portions disposed between adjacent high density portions was produced. At both ends of the core wrap sheet B in the width direction, high-density portions were arranged. The width of the high density portion was about 0.2 mm, and the width of the low density portion was about 0.55 mm, except for both ends in the width direction.

[Core Wrap Sheet C (“Core Wrap C”)]
As the core wrap sheet C, a hydrophilized SMS nonwoven fabric (manufactured by CNC International) having a basis weight of 10 g/m ² and a thickness of 0.2 mm was used.

[Core Wrap Sheet D (“Core Wrap D”)]
As the core wrap sheet D, an air-laid nonwoven fabric (manufactured by Oji Kinocloth Co., Ltd., trade name: Kinocloth) having a basis weight of 60 g/m ² and a thickness of 1 mm was used.

The above core wrap sheet and intermediate layer were evaluated by the following test methods. Table 1 shows the results.

[Evaluation of nonwoven fabric]
In this example, the properties of each nonwoven fabric were evaluated by conducting the following evaluation tests on the intermediate layer and core wrap sheets A to D produced as nonwoven fabrics. If a nonwoven fabric is collected from an absorbent provided in an absorbent article and its properties are evaluated, a cold spray is applied to the absorbent to reduce the bonding strength of the hot-melt adhesive, or an organic solvent is used. is used to dissolve the hot-melt adhesive, each nonwoven fabric is peeled off from the absorbent body, and cut into the dimensions required for each evaluation test.

(tensile strength)
The tensile strength when dry (Dry) and when wet (Wet) is obtained by cutting the manufactured core wrap sheet so that the longitudinal direction is the CD direction and the size of the sample is 25 mm in width x 75 mm in length. For the dry sample, leave it in an atmosphere of 20°C and 65% relative humidity for 24 hours to dry it. % of distilled water is sprayed in a mist and left for 1 minute, and under the conditions of 20 ° C. and a relative humidity of 65%, using "Autograph AG-50NXPlus HS" (manufactured by Shimadzu System Solutions Co., Ltd.) , means the tensile force (N) measured at a chuck interval of 50 mm and a tensile speed of 50 mm/min. For these tensile strengths, the average value of 5 measurements was adopted. Regarding the tensile strength, the tensile strength when the nonwoven fabric is stretched by 30% ("30% tensile strength") and the maximum tensile strength are measured. Then, the displacement and tensile strength at the 0% elongation point where the elongation is 0% with respect to the maximum elongation and the 50% elongation point where the elongation is 50% with respect to the maximum elongation The "first half elastic modulus" was calculated from each difference, and the "second half elastic modulus" was calculated from the difference in the amount of displacement and the tensile strength at the point of 50% elongation and the point of maximum elongation.

(bending resistance)
Bending resistance was measured using a wooden cantilever tester with a polytetrafluoroethylene (PTFE) coated surface, a horizontal top surface, and a 45° bevel, with a bamboo ruler with a minimum scale of 1 mm and a length of 30 mm. Then, a sample piece obtained by cutting the nonwoven fabric so that the dimension in the MD direction was 200 mm and the dimension in the CD direction was 25 mm (n=5) was used. More specifically, with the surface of the sample piece facing up, the sample piece was placed so that the short side of the sample piece was parallel to the edge facing the slope on the upper surface of the bending resistance tester. While lightly pressing the sample piece with a bamboo ruler, slide the sample piece in the direction of the slope, and measure the movement distance (mm) when the sample piece is bent by its own weight. It was carried out by taking the average of the front and back.

(basis weight)
To measure the basis weight, prepare three test pieces cut into a size of 100 mm × 100 mm as a nonwoven fabric sample, and measure the mass of these with a direct reading balance (for example, Kensei Kogyo Co., Ltd., electronic balance HF −300), and the mass per unit area (g/m ² ) of the nonwoven fabric calculated based on the average value of the masses of three test pieces was taken as the basis weight of the nonwoven fabric.

(thickness)
The thickness of the nonwoven fabric was measured with a nonwoven fabric thickness gauge “UF-60A manufactured by Daiei Kagaku Kiki Seisakusho” (measurement tip φ44 mm, measurement load 0.49 N). The average value of 10 sample pieces was used as the thickness.

Table 1 shows the above results.

[Examination of nonwoven fabric properties]
(About the core wrap sheet)
As shown in Table 1, the 30% tensile strength of the core wrap sheet C is too high, so the elongation as a nonwoven fabric is low, and when used as a core wrap sheet, the swelling of the superabsorbent polymer may be inhibited. was concerned about gender. Although the core wrap sheet D has a low tensile strength, there is a concern that it may break at a certain strength or higher and may not sufficiently retain the superabsorbent polymer. On the other hand, the core wrap sheets A and B have a low 30% tensile strength and a large elongation, but the swelling is lower than the first half elastic modulus, which is assumed to correspond to the initial swelling when used as a core wrap sheet. Since the late elastic modulus, which is assumed to correspond to the late stage, is high, it is difficult to inhibit the swelling of the superabsorbent polymer and is expected to have excellent absorption performance. was predicted.

(About middle layer)
As shown in Table 1, the intermediate layer A had substantially the same 30% tensile strength, maximum tensile strength, maximum elongation, first half elastic modulus, and second half elastic modulus when wet and when dry. From this result, it was predicted that the absorbent body provided with the intermediate layer A would be excellent in repeated absorption of bodily fluids.

[Preparation of absorber]
Absorbent bodies of Examples 1 and 2 and Comparative Examples 1 and 2 were produced in the combinations shown in Table 2 from the samples of the intermediate layer and the core wrap sheet produced as described above.

(1) A non-woven fabric for the core wrap sheet of the lower layer is cut into a width of 140 mm and a length of 400 mm, and a hot-melt adhesive is applied to the entire upper surface of the cut piece with a basis weight of 7 g/m ² using a spiral coater.
(2) Two superabsorbent polymer-free regions with a width of 10 mm are provided at a distance of 30 mm in the range of 100 mm in width in the center of the width direction on the upper surface of the nonwoven fabric for the core wrap sheet of the lower layer, and superabsorbent A flexible polymer (manufactured by Sumitomo Seika Co., Ltd., Aqua Keep) is evenly dispersed at a basis weight of 155 g/m ² .
(3) Cut an air-through nonwoven fabric (for intermediate layer) with a basis weight of 40 g/m ² into a width of 100 mm × length of 400 mm, and apply a hot melt adhesive on ^both sides and the entire surface using a spiral coater. Apply with
(4) The air-through nonwoven fabric of (3) above is placed on top of the nonwoven fabric for the lower layer core wrap sheet of (2) above. A superabsorbent polymer (Sumitomo Seika Co., Ltd., AQUA KEEP) is uniformly sprinkled on the upper surface of the air-through nonwoven fabric with a basis weight of 225 g/m ² over a width of 100 mm in the central portion in the width direction.
(5) A nonwoven fabric for the core wrap sheet of the upper layer is cut into a width of 100 mm and a length of 400 mm, and a spiral coater is used to apply a hot-melt adhesive to the entire surface of the cut piece at a basis weight of 7 g/m ² .
(6) Place the upper nonwoven fabric for the core wrap sheet on the top surface of the air-through nonwoven fabric of (4) with the surface coated with the hot-melt adhesive facing down. Then, 20 mm portions on each side in the width direction of the nonwoven fabric for the core wrap sheet in the lower layer are folded inward and sealed. An absorber is thereby formed.
(7) After that, the absorber is pressed with a pressing machine whose pressing pressure is adjusted so that the absorber has a thickness of 2.5 mm. Thereby, an absorbent body having a uniform thickness is manufactured.

Absorption performance and repeated absorption of body fluids were evaluated for the resulting absorbent body. As a result, compared to the absorbent bodies of Comparative Examples 1 and 2, the absorbent bodies of Examples 1 and 2 were superior in absorption performance, and corresponded to the fact that the core wrap sheets had high-density portions and low-density portions. It was excellent in repeated absorption of body fluids.

L Longitudinal direction W Width direction C Width direction intermediate part E Width direction both ends T Thickness direction Tc Thickness direction central plane 1 Disposable diaper 3 Top sheet 5 Back sheet 7 Leakage-proof wall 9 Elastic member 15 Tape fastener 17 Absorber 18 th 1 absorbent core layer 19 intermediate layer 20 second absorbent core layer 21 absorbent core 22 central sheet portion 23 outer sheet portion 24 first core wrap sheet portion 25 second core wrap sheet portion 26 core wrap sheet 27 overlapping portion 28 Superabsorbent polymer nonexistent region 29 junction 30 middle junction 31 edge 32 high density portion 33 low density portion 34 upper surface 35 lower surface

Claims (7)

having a top surface and a bottom surface and orthogonal longitudinal, width, and thickness directions;
An absorbent body having an absorbent core and a core wrap sheet provided at least one of above and below the absorbent core in the thickness direction,
The absorbent core is made of a superabsorbent polymer,
The absorbent core is a laminated absorbent core in which a first absorbent core layer, an intermediate layer, and a second absorbent core layer are laminated in this order from the upper surface toward the lower surface,
The core wrap sheet is a flat water-absorbent nonwoven fabric in which water-absorbent fibers are entangled with each other,
The water absorbent nonwoven fabric is
a plurality of high-density portions extending along the longitudinal direction and arranged side by side in the width direction;
a plurality of low-density portions extending along the longitudinal direction and arranged between adjacent high-density portions of the plurality of high-density portions;
The plurality of high-density portions and the plurality of low-density portions are gear-machined portions ,
The core wrap sheet is
enclosing the laminated absorbent core,
a first core wrap sheet portion located above the central plane in the thickness direction of the absorbent body;
a second core wrap sheet portion located below the central plane in the thickness direction of the absorbent body;
including
The first core wrap sheet portion includes:
a central sheet portion arranged toward the center in the width direction;
A pair of outer sheet portions arranged on both outer sides in the width direction,
Each of the widthwise outer portions of the central sheet portion and each of the pair of outer sheet portions overlap in the thickness direction and form a pair of overlapping portions extending in the longitudinal direction. ,
The dimension in the width direction of the first absorbent core layer is smaller than the dimension in the width direction of the second absorbent core layer,
The first absorbent core layer is arranged on the second absorbent core layer in an intermediate portion in the width direction,
The pair of overlapping portions are arranged at both ends in the width direction on the second absorbent core layer,
Absorber. In each of the pair of overlapping portions, each of the pair of outer sheet portions is arranged on the upper surface side of the central sheet portion, and each of the pair of outer sheet portions is located on the side of the central sheet portion. 2. The absorbent article of claim 1, wherein edges are spaced apart from said central sheet portion . The absorbent body according to claim 1 or 2, wherein the intermediate layer is a liquid-permeable nonwoven fabric having hydrophilicity and liquid permeability. 4. The absorbent body according to claim 3, wherein said liquid-permeable nonwoven fabric is an air-through nonwoven fabric made of thermoplastic synthetic fibers. 5. Claims 1 to 4, wherein the absorbent body further comprises a superabsorbent polymer absent region extending in the longitudinal direction in the second absorbent core layer and having no superabsorbent polymer present in the thickness direction. Absorber according to any one of the above. The absorbent body according to any one of claims 1 to 5 , wherein the high-density portions are arranged at both ends of the core wrap sheet in the width direction. In the core wrap sheet, the relationship between the first half elastic modulus and the second half elastic modulus in the width direction when dry and wet is both (first half elastic modulus) < (second half elastic modulus).
The absorbent body according to any one of claims 1 to 6 .

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