JP7411430B2 - Absorbent bodies and absorbent articles - Google Patents

Description

The present invention relates to an absorbent body for absorbent articles.

Absorbent articles such as disposable diapers and sanitary napkins generally have a top sheet placed relatively close to the wearer's skin, and a back sheet placed relatively far from the wearer's skin. , and an absorbent body interposed between both sheets. This absorbent body is typically made of a stack of fiber materials such as wood pulp, and the stack often carries water-absorbing polymer particles. Absorbent bodies made of stacks of fiber materials are relatively bulky and thick, so they have excellent cushioning properties, but on the other hand, because they are bulky, the appearance of the absorbent article does not look clean and the appearance is poor. There have been problems such as giving a stiff and uncomfortable feeling to the wearer of the sex article. In particular, if the wearer excretes body fluids such as urine or menstrual blood while wearing an absorbent article, the absorbent absorbs and retains the excrement and swells, making this problem even more serious. . Therefore, attempts are being made to make the absorber thinner.

As a conventional technique related to making the absorbent body thinner, for example, Patent Document 1 discloses an upper layer absorbent body made of pulp and a water-absorbing polymer, and a two-layer sheet disposed adjacent to the non-skin-facing side of the upper layer absorbent body. An absorbent body comprising a lower layer absorbent body and a water-absorbing polymer disposed therebetween is described. The upper absorbent core is formed with an opening that extends in the longitudinal direction of the absorbent article to which the absorbent core is applied (the front-rear direction of the wearer). The lower layer absorbent body is divided into a plurality of water-absorbing polymer placement regions in which particulate water-absorbing polymer is encapsulated between the two sheets bonded to each other, and between adjacent water-absorbing polymer placement regions. However, the flow path portion is recessed from the water-absorbing polymer arrangement region. The water-absorbing polymer does not exist in the flow path portion, or exists with a lower basis weight than the water-absorbing polymer arrangement region. Therefore, the water-absorbing polymer is not uniformly distributed in the lower absorbent layer. According to the absorbent body described in Patent Document 1, by employing the sheet-like lower layer absorbent body mainly made of a water-absorbing polymer, a sufficient amount of absorption can be ensured despite being thin. Since the upper absorbent layer also contains a water-absorbing polymer, it is said to be able to solve the problem of difficulty retaining liquid and causing backflow when it is made only of pulp.

Patent Document 2 also describes an absorbent body having a two-layer structure similar to Patent Document 1. In the absorbent body described in Patent Document 2, the lower layer of the two-layer structure, which is relatively far from the wearer's skin, does not substantially contain cellulose and is mainly composed of a water-absorbing polymer. Further, Patent Document 3 describes a water-absorbent sheet composition having a structure in which an absorbent layer containing a water-absorbing resin and an adhesive is sandwiched between two or more sheets of hydrophilic nonwoven fabric, in which the absorbent layer has a thickness that is It is divided into directions.

Unexamined Japanese Patent Publication No. 2018-50987 Special Publication No. 2010-529879 International Publication No. 2010/076857

Most conventional technologies aimed at making absorbers thinner have focused on reducing the thickness before liquid absorption, and have focused on various performances such as flexibility and liquid absorption performance after liquid absorption. The reality is that there are very few.

In addition, from the viewpoint of reducing discomfort when wearing the absorbent article and improving liquid uptake and dispersibility, the absorbent body for absorbent articles should be made in such a way that the forming material of the absorbent body does not exist or is lower than the surrounding area. It is known that a part having a low basis weight (hereinafter also referred to as a "forming material non-existing part") is provided (for example, Patent Document 1). However, according to the findings of the present inventors, when a thin absorbent material having a non-forming material area and an uneven surface is used in a disposable diaper, the wearer's excrement may be removed while wearing the diaper. Due to the swelling of the absorbent body due to absorption, the area where the absorbent body is placed on the outer surface of the diaper swells in a concave and convex shape to the extent that it can be seen from the outside in a manner corresponding to the unevenness of the absorbent body, and the area where the absorbent body is placed on the outer surface of the diaper swells to the extent that it is visible from the outside. It has been found that it can become uneven when touched. This phenomenon in which unevenness occurs on the outer surface of an absorbent article due to swelling of an absorbent material having an uneven surface is completely natural and does not pose any problem in terms of the quality of the absorbent article. However, this may give the impression to general consumers that the absorbent body is broken and its function is impaired. For example, if the above-mentioned phenomenon occurs in a disposable diaper worn by an infant, a third party such as a mother who confirms the occurrence of the phenomenon may mistakenly believe that the absorbent material is broken and replace the diaper with a diaper that is still usable. There may be a situation where you have to replace it. The reality is that there are almost no techniques that focus on the problems unique to absorbers having non-forming material portions, particularly thin absorbers.

Therefore, it is an object of the present invention to have practically sufficient liquid absorption performance even when the thickness is reduced, to reduce discomfort when wearing an absorbent article, and to provide an absorbent material on the outer surface of the absorbent article after absorbing liquid. The present invention relates to providing an absorbent body for an absorbent article that does not easily generate unevenness that may lead to breakage.

The present invention has a vertical direction corresponding to the front and back direction of the wearer and a horizontal direction perpendicular to the vertical direction, and has a crotch area located in the crotch area of the wearer, and a crotch area that is closer to the wearer's abdomen than the crotch area. This is an absorbent body used in an absorbent article including a ventral part disposed on the side and a dorsal part disposed on the dorsal side of the wearer with respect to the crotch area.
In one embodiment of the absorbent body of the present invention, an intermediate sheet, a first sheet disposed on the non-skin facing surface side of the intermediate sheet, and a second sheet disposed on the skin facing surface side of the intermediate sheet are provided. A first core containing at least a water-absorbing polymer as a water-absorbing material is interposed between the first sheet and the intermediate sheet, and a liquid-absorbing material is interposed between the intermediate sheet and the second sheet. A water-absorbent second core that swells with water is interposed therebetween.
In one embodiment of the absorbent body of the present invention, a through hole passing through the second core in the thickness direction is formed in a region corresponding to the crotch portion of the second core, and a region overlaps with the through hole in plan view. In the second core, the second sheet and the intermediate sheet are closer to each other than a region of the second core that overlaps a non-through-hole portion around the through-hole in a plan view.
In one embodiment of the absorbent body of the present invention, 90% by mass or more of the material forming the first core is a water-absorbing polymer.
In one embodiment of the absorbent body of the present invention, the water-absorbing polymer is uniformly distributed in a region corresponding to the crotch portion of the first core.
In one embodiment of the absorbent body of the present invention, the absorbent body has a concave portion on a skin-facing surface side and a non-skin-facing surface side in a region that overlaps with the through-hole in a plan view in a liquid-absorbing state, and The depth of the recess on the surface side is 40% or less of the depth of the recess on the skin-facing surface.

The present invention also provides an absorbent article comprising the above-described absorbent body of the present invention.
Other features, advantages and embodiments of the invention are described below.

According to the present invention, even if the thickness is reduced, it has practically sufficient liquid absorption performance, reduces discomfort when wearing the absorbent article, and prevents breakage of the absorber from occurring on the outer surface of the absorbent article after absorbing liquid. Provided are an absorbent body for an absorbent article that does not easily generate unevenness reminiscent of the above, and an absorbent article equipped with the absorbent body.

FIG. 1 is a developed plan view schematically showing the skin-facing surface side (topsheet side) of a deployable disposable diaper, which is an embodiment of the absorbent article of the present invention, in an expanded and stretched state. FIG. 2 is a cross-sectional view schematically showing a cross section taken along line II in FIG. FIG. 3 is a plan view schematically showing the skin-facing side of the absorber in the disposable diaper of FIG. 1. FIG. 4 is a cross-sectional view schematically showing a cross section along the thickness direction of the absorbent body shown in FIG. 3 at the center in the longitudinal direction (vertical center line indicated by the symbol CLx). 5 is a simplified schematic cross-sectional view of the absorber shown in FIG. 4, FIG. 5(a) shows the state of the absorber before liquid absorption, and FIG. 5(b) shows the absorber Indicates the liquid absorption state. FIGS. 6(a) and 6(b) are transverse cross-sectional views each schematically showing a cross section along the thickness direction of a part of an embodiment of the absorber of the present invention. FIGS. 7(a) to 7(c) are schematic plan views of the first core side laminated structure in the example or comparative example, respectively. FIG. 8 is for measuring the bending rigidity change rate BR in the longitudinal and lateral directions per thickness change before and after liquid absorption of a laminated structure (first core side laminated structure) consisting of a first sheet, a first core, and an intermediate sheet. FIG. 2 is an explanatory diagram of a sample preparation method. FIG. 9 shows the preparation of a sample for measuring the bending rigidity change rate BR in the diagonal direction per thickness change before and after liquid absorption of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet. It is an explanatory diagram of a method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on preferred embodiments thereof with reference to the drawings. In addition, in the description of the following drawings, the same or similar parts are given the same or similar symbols. The drawings are basically schematic, and the ratio of each dimension may differ from the actual one.

The absorbent article of the present invention has a vertical direction (indicated by the symbol "X" in the figure) corresponding to the front-back direction of the wearer, that is, a direction extending from the ventral side to the dorsal side via the crotch area, and a vertical direction perpendicular to the vertical direction. It has a horizontal direction (indicated by the symbol "Y" in the figure).
In the following description, unless otherwise specified, the longitudinal direction refers to the longitudinal direction of the absorbent article or the longitudinal direction of its constituent members (for example, an absorbent body), and the lateral direction refers to the lateral direction of the absorbent article or the longitudinal direction thereof. This is the direction along the lateral direction of the component.
The absorbent article of the present invention includes an absorbent body (indicated by the reference numeral "10" in the figure) that absorbs and retains body fluids.
1 and 2 show a disposable diaper 1 which is an embodiment of the absorbent article of the present invention, and the diaper 1 has the above-described configuration.

In the longitudinal direction It is divided into three parts: a ventral part A disposed on the ventral side (front side) of the wearer, and a dorsal part C disposed on the dorsal side (rear side) of the wearer with respect to the crotch area B. The abdominal part A and the dorsal part C typically each include a waist part that is placed around the wearer's waist when the diaper 1 is worn. The ventral side part A is a part of the front body of the diaper 1, and the back side part C is a part of the back body of the diaper 1. The crotch area B exists from the front body to the back body of the diaper 1.
In the present invention, the abdominal part A, the crotch part B, and the dorsal part C can be each area when the diaper 1 in the unfolded and stretched state is divided into three equal parts in the longitudinal direction X. The term "expanded and stretched state" as used herein means that the diaper is in the unfolded state as shown in Figure 1, and the diaper in the unfolded state is adjusted to the design dimensions (with no influence of the elastic members) by stretching the elastic members of each part. The state in which it is expanded until it has the same dimensions as when expanded flat.

The diaper 1 is a so-called deployable disposable diaper, and as shown in FIG. , the non-skin-facing surface of the abdominal part A is provided with a fastening area 9 to which the fastening part 7 can be fastened.
The diaper 1 also includes an absorbent body 2 including an absorbent body 10 that absorbs and retains body fluids such as urine excreted by the wearer, and a flap portion 5 extending outward from the periphery of the absorbent body 2. .

The absorbent main body 2 includes a liquid-permeable top sheet 3 forming a skin-facing surface, a liquid-impermeable, slightly liquid-permeable, or water-repellent back sheet 4 forming a non-skin-facing surface, and both sheets 3, 4. It has a liquid-retaining absorbent body 10 interposed therebetween, and these are integrated by known bonding means such as adhesive. The absorbent main body 2 extends in the longitudinal direction X from the ventral side part A to the dorsal side part C. As the top sheet 3 and the back sheet 4, those conventionally used for this type of absorbent article can be used without particular limitation. As the topsheet 3, for example, various nonwoven fabrics and perforated films can be used. As the back sheet 4, for example, a resin film or a laminate of a resin film and a nonwoven fabric can be used.

As used herein, "skin-facing surface" refers to the surface of an absorbent article or its constituent members (e.g. absorbent body) that faces the wearer's skin when the absorbent article is worn, that is, the surface facing the wearer's skin relative to the wearer's skin. The "non-skin-facing surface" refers to the surface of the absorbent article or its constituent members that faces away from the skin when the absorbent article is worn, i.e., the side that is relatively far from the wearer's skin. It's on the side. Note that "when worn" here means a state in which the normal proper wearing position, that is, the correct wearing position of the absorbent article is maintained. In FIG. 2 and FIGS. 4 to 6 (cross-sectional views along the thickness direction) of the present application, the upper surface (relatively located above) of each component (for example, the absorber 10) is the skin-facing surface, and the lower surface (relatively The surface located below the skin) is the non-skin facing surface.

The flap portion 5 is constituted by a member extending outward from the periphery of the absorbent main body 2, and is a non-disposed portion of the absorbent body. In this embodiment, as shown in FIG. 2, the topsheet 3 covers the entire skin-facing surface of the absorbent core 10, and the backsheet 4 covers the entire non-skin-facing surface of the absorbent core 10, and both The sheets 3 and 4 further extend outward in the horizontal direction Y from both side edges of the absorbent body 2 along the longitudinal direction 2 and side flaps extending outward in the lateral direction Y from the imaginary extension lines of the both side edges are formed. The plurality of members constituting the flap portion 5 are joined to each other by known joining means such as adhesive, heat sealing, and ultrasonic sealing.

As shown in FIGS. 1 and 2, leak-proof cuffs 6 that stand up toward the skin of the wearer when worn are arranged along both sides of the absorbent main body 2 in the longitudinal direction X. More specifically, a pair of liquid-resistant or water-repellent and breathable leak-proof cuff forming sheets 60 are provided on both sides of the skin-facing surface of the absorbent main body 2 along the longitudinal direction X. Leak-proof cuffs 6, 6 are arranged. These pair of leak-proof cuff forming sheets 60, 60 are each fixed at one end side in the lateral direction Y to another member (the top sheet 3 and the back sheet 4 in the illustrated form), The other end is a free end that is not fixed to another member. At the free end of each leak-proof cuff-forming sheet 60, a leak-proof cuff-forming elastic member 61 is arranged in a stretched state in the longitudinal direction X so that it can expand and contract in the same direction. When the diaper 1 is worn, the contractile force of the elastic member 61 for forming a leak-proof cuff causes the free end side of the sheet 60 for forming a leak-proof cuff, at least in the crotch area B, to raise the fixing part 62 with other members to the proximal end. The leak-proof cuff 6 stands up on the wearer's side, and by standing up the leak-proof cuff 6, the leakage of urine and other excreta to the outside in the lateral direction Y is prevented.

A plurality of elastic members 31 for forming waist circumference gathers are disposed in the flap part 5 at the end in the longitudinal direction X, that is, at the waist end of each of the abdominal part A and the dorsal part C, so as to be expandable and contractable in the lateral direction Y. The plurality of elastic members 31 are arranged intermittently in the vertical direction X at predetermined intervals. In this way, since the elastic member 31 is arranged in a state where its elasticity is expressed, the waist end portions of the ventral side part A and the dorsal side part C, where the elastic member 31 is arranged, have a substantially A continuous annular waist gather (gather around the waist) is formed.
Further, in the leg portions of the flap portion 5 that are arranged around the wearer's legs when wearing the diaper 1, a leg gather forming elastic member 32 that is stretchable in the longitudinal direction The elastic members 32 extend in the longitudinal direction X over the entire length thereof, and when the diaper 1 is worn, the elastic members 32 contract to form leg gathers in the leg portions.
These gather forming elastic members 31 and 32 are made of a plurality of sheets (in this embodiment, two types of the top sheet 3, the back sheet 4, and the leak-proof cuff forming sheet 60) constituting the flap portion 5. They are clamped and fixed in an extended state by bonding means such as adhesive between them.
The form of each of the elastic members 61, 31, and 32 described above is not particularly limited, and may be, for example, thread-like or string-like (such as flat rubber) with a rectangular, square, circular, or polygonal cross section, or a multifilament-type thread-like material. It is possible to use the following.

The absorbent body 10 included in the diaper 1 is one embodiment of the absorbent body of the present invention. 3 shows a side of the skin-facing surface of the absorbent core 10 (the surface facing the top sheet 3), and FIG. 4 shows a cross-section along the thickness direction of the absorbent core 10 at the center position in the longitudinal direction X. There is. In addition, in FIG. 4, from the viewpoint of easy understanding, members that are actually in close contact with each other are shown separated from each other, and FIG. 4 does not necessarily represent the actual situation. As shown in FIGS. 3 and 4, the absorbent body 10 includes an intermediate sheet 13 and a first sheet disposed on the non-skin facing side of the intermediate sheet 13 (the side farther from the wearer's skin than the intermediate sheet 13). 11, and a second sheet 12 disposed on the skin-facing side of the intermediate sheet 13 (the side closer to the wearer's skin than the intermediate sheet 13), and between the first sheet 11 and the intermediate sheet 13. A water-absorbing first core 14 is interposed, and a water-absorbing second core 15, which swells due to liquid absorption, is interposed between the intermediate sheet 13 and the second sheet 12. In this way, the second sheet 12 side of the absorber 10 is used as the liquid-receiving surface side that first comes into contact with the liquid to be absorbed.

As the three types of sheets (first sheet 11, second sheet 12, and intermediate sheet 13) included in the absorber 10, sheets having liquid permeability or liquid absorbency can be used, and typically, The fiber sheet is mainly composed of fibers, that is, the fiber content exceeds 50% by mass. The constituent fibers of the three types of sheets include, for example, wood pulp such as softwood pulp and hardwood pulp, natural fibers such as non-wood pulp such as cotton pulp and hemp pulp; modified pulp such as cationized pulp and mercerized pulp ( Synthetic fibers containing resins such as polyethylene and polypropylene (cellulose fibers) are mentioned above, and one type of these can be used alone or two or more types can be used in combination. Examples of the forms of the three types of sheets include paper, woven fabric, and nonwoven fabric, and examples of the nonwoven fabric include air-through nonwoven fabric, heat roll nonwoven fabric, spunlace nonwoven fabric, spunbond nonwoven fabric, meltblown nonwoven fabric, and spunbond-meltblown fabric. - Spunbond (SMS) non-woven fabrics. The three types of sheets typically have a single-layer structure made of one of these types, but may also have a laminated structure in which two or more types are laminated and integrated. The three types of sheets may have the same or different compositions and shapes.

In the present embodiment, the length (width) of the second sheet 12 in the lateral direction Y is the same as that of the other constituent members (the first sheet 11, the intermediate sheet 13, the first core 14, and the second core 15) of the absorbent body 10. ) consists of one wide sheet that is longer than the width of the widest part (maximum width). More specifically, the second sheet 12 of this embodiment has a width that is between twice and three times the maximum width, and covers the entire skin-facing surface of the second core 15, as shown in FIG. It covers and extends outward in the horizontal direction Y from each of both side edges of the second core 15 along the longitudinal direction , covering the entire non-skin facing surface of the first sheet. That is, the second sheet 12 covers the entire skin-facing surface and non-skin-facing surface of the laminated structure including the first sheet 11, intermediate sheet 13, first core 14, and second core 15.

In addition, in the present invention, the second sheet 12 does not need to include the extension part 12E, and the second sheet 12 has a width comparable to the maximum width of the second core 15 that contacts the second sheet 12. It is sufficient if it has the following. Typically, the other constituent members of the absorbent body 10 (the first sheet 11, the intermediate sheet 13, the first core 14, and the second core 15) other than the second sheet 12 have a maximum width, that is, the maximum width in the lateral direction Y. The lengths are approximately the same.

The first core 14, that is, the layer sandwiched between the first sheet 11 and the intermediate sheet 13, contains at least a water-absorbing polymer 20 as a water-absorbing material. The first core 14 is characterized in that 90% by mass or more of its forming material is a water-absorbing polymer. That is, the "water-absorbing polymer occupancy" (the ratio of the content mass of the water-absorbing polymer to the total mass of the material forming the core) of the first core 14 is 90% by mass or more, and the first core 14 has a water-absorbing polymer 20 It is mainly composed of. The "forming material of the first core 14" (core forming material) here refers to the space between two sheets (specifically, the first sheet 11 and the intermediate sheet 13) located on both sides of the first core 14. means a substance that exists in However, the core forming material does not include the adhesive applied to the opposing surfaces (inner surfaces) of the two sheets. Therefore, the adhesives indicated by reference numerals 22 and 23 in FIG. 4 are not the core forming material of the first core 14.

The first core 14 typically contains only the water-absorbing polymer 20 as the water-absorbing material and does not contain water-absorbing fibers such as wood pulp, or even if it does contain water-absorbing fibers, the second core 15 The content of water-absorbing fibers is much smaller (for example, 10% by mass or less) than the content of water-absorbing fibers in .

As the water-absorbing polymer 20, a hydrogel material capable of absorbing and retaining water can generally be used, and for example, a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid can be used. Examples thereof include polyacrylic acid and its salts, and polymethacrylic acid and its salts, and specifically, acrylic acid polymer partial sodium salts. The shape of the water-absorbing polymer 20 is not particularly limited, and may be, for example, spherical, tufted, lump-like, bale-like, fibrous, irregularly shaped, or particles of a combination thereof. From the viewpoint of increasing the uniformity of dispersion of the water-absorbing polymer 20 during the production of the first core 14 (absorbent body 10) and improving the liquid absorption performance of the absorbent body 10, particles of the same shape are used for the water-absorbing polymer 20. is preferable, and spherical particles are also preferable.

The adhesives 22 and 23 serve to fix the water-absorbing polymer 20 contained in the first core 14 to the first sheet 11 and/or the intermediate sheet 13, as well as to bond the sheets 11 and 13 together. The adhesive 22 is applied to the surface (inner surface) of the first sheet 11 facing the intermediate sheet 13 , and the adhesive 23 is applied to the surface (inner surface) of the intermediate sheet 13 facing the first sheet 11 . It is what was done. As the adhesives 22 and 23, any adhesive that can be used for bonding members together in this type of absorbent article can be used without particular limitation, such as a hot melt adhesive. The adhesive 22 and the adhesive 23 may be the same type of adhesive or different types of adhesive, and typically the former. Note that the adhesives 22 and 23 will be described later.

The adhesive application pattern for the adhesive 22 on the first sheet 11 side and the adhesive 23 on the intermediate sheet 13 side may be the same or different. As an example of the latter case, the adhesive on the liquid-receiving surface of the first core 14, which first comes into contact with the liquid to be absorbed, is applied to a predetermined application area (for example, the area where the water-absorbing polymer 20 is present) on the application surface. The adhesive is applied so that there is a non-applied part of the adhesive, and the adhesive on the side opposite to the liquid-receiving surface side is substantially free of the non-applied part of the adhesive in a predetermined application area on the surface to be coated. An example of this is a form in which the material is coated in this way (so-called solid coating). There is a concern that the liquid permeability and liquid absorption performance of the first core 14 may decrease depending on the type of adhesive, application pattern, etc., but as in this embodiment, the liquid receiving surface side is not coated with adhesive. Such concerns can be eliminated by applying the adhesive so that there is substantially no adhesive-unapplied area on the side opposite to the liquid-receiving surface.
In this embodiment, as shown in FIG. 2, the absorber 10 is used with the second sheet 12 side as the liquid-receiving surface side, so in the first core 14, the intermediate sheet 13 side is the liquid-receiving surface side (diaper 1 The first sheet 11 side is the side opposite to the liquid receiving surface side (the side relatively far from the wearer's skin of the diaper 1). Therefore, the application pattern of the adhesive 23 on the intermediate sheet 13 side is made into a pattern in which areas where the adhesive 23 is applied and non-applied areas coexist, and the application pattern of the adhesive 22 on the first sheet 11 side is set as a so-called solid coating pattern. Bye. Examples of patterns in which adhesive-applied areas and non-applied areas coexist include patterns in which adhesive-applied areas have a spiral shape, a summit shape, an omega shape, a curtain shape, or a stripe shape when viewed from above. It will be done.

In this embodiment, the adhesive is applied on both sides of the first core 14 in the thickness direction, that is, on both the first sheet 11 side and the intermediate sheet 13 side, but in the present invention, the adhesive is applied on either side. Adhesive may be applied only to the surface. The basis weight of the adhesive placed on both sides of the first core 14 (if the adhesive is applied to both the first sheet 11 side and the intermediate sheet 13 side, the total basis weight) is the water absorption From the viewpoint of the balance between fixation of the flexible polymer 20 and liquid permeability or liquid absorption performance, it is preferably 3 g/m ² or more, more preferably 5 g/m ² or more, and preferably 50 g/m ² or less, more preferably It is 30g/ ^m2 or less.

The second core 15, that is, the layer sandwiched between the intermediate sheet 13 and the second sheet 12, contains at least water-absorbing fibers (not shown) and a water-absorbing polymer 20 as water-absorbing materials. The second core 15 is typically composed mainly of a water-absorbing material. The content of the water-absorbing material in the second core 15 is at least 50% by mass or more, and 100% by mass, that is, the entire core forming material may be the water-absorbing material.
As the water-absorbing polymer 20 in the second core 15, the same material as that contained in the first core 14 can be used.
Examples of water-absorbing fibers include wood pulps such as softwood pulp and hardwood pulp, natural fibers such as non-wood pulps such as cotton pulp and hemp pulp; modified pulps such as cationized pulp and mercerized pulp (including cellulose fibers); ); hydrophilic synthetic fibers and the like, and one type of these can be used alone or two or more types can be used in combination. The water absorbent fibers contained in the second core 15 are typically cellulose fibers.

As used herein, the term "water-absorbing" with respect to fibers is easily understood by those skilled in the art, as in the case of pulp being water-absorbing, for example. Similarly, it can be easily understood that thermoplastic fibers are non-water absorbing. On the other hand, the degree of water absorbency of fibers can be determined by the moisture content measured by the method described below, allowing comparison of relative differences in water absorbency and also defining a more preferable range. The moisture content of the water-absorbing fiber is preferably 6% or more, more preferably 10% or more. On the other hand, the water content of the non-water-absorbing fiber is preferably less than 6%, more preferably less than 4%.

<Method for measuring moisture content>
The moisture content was calculated by applying the moisture content test method of JIS P8203. That is, the fiber sample was allowed to stand in a test room at a temperature of 40° C. and a relative humidity of 80% RH for 24 hours, and then the weight F (g) of the fiber sample before absolute drying was measured in the room. Thereafter, the fiber sample was left to stand still for 1 hour in an electric dryer (for example, manufactured by Isuzu Seisakusho Co., Ltd.) at a temperature of 105±2° C. to completely dry the fiber sample. After the absolute drying process, in a test room under standard conditions at a temperature of 20 ± 2°C and a relative humidity of 65 ± 2%, the fiber sample was wrapped in Saran Wrap (registered trademark) manufactured by Asahi Kasei Corporation, and Si silica gel (e.g. ( manufactured by Toyota Kako Co., Ltd.) in a glass desigator (for example, manufactured by Techjam Co., Ltd.) and allowed to stand until the fiber sample reaches a temperature of 20±2°C. Thereafter, the constant weight F' (g) of the fiber sample is weighed, and the moisture content of the fiber sample is determined using the following formula.
Moisture percentage (%) = {(FF')/F'} x 100

The water-absorbing polymer occupancy of the second core 15 is preferably 30% by mass or more, more preferably 40% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less.
The content of water absorbent fibers in the second core 15 is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less.

The second core 15 can be manufactured according to a conventional method using a known fiber stacking device equipped with a rotating drum. A fiber stacking device typically has a rotating drum with a stacking recess formed on its outer circumferential surface, and a flow path for conveying core forming material (water-absorbing fibers, water-absorbing polymer) to the stacking recess. duct, and the core is conveyed by riding on the air flow generated in the flow path by suction from the inside of the rotating drum while rotating the rotating drum around the rotation axis along the circumferential direction of the drum. The forming material is stacked in the stacking recess. The stacked material formed in the stacking recess by this stacking process is the second core 15. The second core 15 can be referred to as a "stacking type absorbent core" due to this typical manufacturing method.

As shown in FIGS. 1 to 4, a through hole 15N that penetrates the second core 15 in the thickness direction is formed in a region corresponding to the crotch portion B of the second core 15 (arranged in the crotch portion B). ing. The through-hole 15N is a material-free portion where the core-forming material (water-absorbing fiber, water-absorbing polymer, etc.) of the second core 15 does not exist. However, the core forming material of the second core 15 that has fallen off from the peripheral portion (the non-through hole formed portion 15M described later) may enter the through hole 15N, and the core forming material may be present in the through hole 15N. In such a case, the basis weight of the core forming material in the through hole 15N is lower than that of the surrounding area (for example, an area within 10 mm in the vertical direction X or the horizontal direction Y from the through hole 15N); It is preferably 20% or less, more preferably 10% or less.
In the second core 15, a through-hole non-formed portion 15M in which the through-hole 15N is not formed exists around the through-hole 15N, and the through-hole 15N is surrounded by the through-hole non-formed portion 15M. The second core 15 typically includes a through hole 15N and a non-through hole portion 15M.

In this embodiment, the through holes 15N are formed symmetrically with respect to a horizontal center line CLy that bisects the second core 15 in the horizontal direction Y and extends in the vertical direction X, as shown in FIGS. 1 and 3. , are formed in pairs on both sides of the horizontal center line CLy. The pair of through holes 15N each have a long shape in the vertical direction X (longitudinal direction of the second core 15) in plan view, specifically a rectangular shape.

The through holes 15N contribute to reducing discomfort when wearing the diaper 1, improving liquid uptake and liquid dispersibility, and the like. In other words, the through hole 15N acts as a deformation guiding portion (flexible shaft) when the second core 15 including the second core 15 bends or deforms in response to an external force such as body pressure. Deformation that conforms to the wearer's body shape is promoted, and as a result, the discomfort when wearing the diaper 1 is reduced, and the feeling of wearing and fit can be improved. In addition, the through holes 15N function as a flow path for excreta such as urine that is to be absorbed by the absorbent body 10, promote diffusion of the excreta in the surface direction, and contribute to effective utilization of the liquid absorption performance of the absorbent body 10. obtain. Since the through-hole 15N plays such a role, it is preferable to arrange it in a part of the second core 15 that is likely to receive external forces such as body pressure and where excrement is likely to be concentrated. From such a viewpoint, the through hole 15N is preferably arranged in a portion of the second core 15 located in the crotch area B. From the same viewpoint, the through hole 15N preferably extends across the longitudinal center line CLx of the absorber 10 in the longitudinal direction X, as shown in FIG.

The length L in the vertical direction X (longitudinal direction) of the through hole 15N (see FIG. 3) is preferably 20 mm with respect to the length L0 in the vertical direction % or more, more preferably 30% or more, and preferably 95% or less, more preferably 85% or less.
The length of the through hole 15N in the lateral direction Y, that is, the width W (see FIG. 3) is preferably 1 mm or more, more preferably 2 mm or more, and preferably 25 mm or less, more preferably 20 mm or less.
The distance G (see FIG. 3) between two through holes 15N, 15N adjacent to each other in the lateral direction Y is preferably 10 mm or more, more preferably 15 mm or more, and preferably 80 mm or less, more preferably 60 mm or less. .

The through-hole 15N is a portion formed by intentionally inhibiting the stacking of the forming material (water-absorbing fiber, water-absorbing polymer, etc.) during the fiber-stacking process of the forming material (water-absorbing fiber, water-absorbing polymer, etc.) during the production of the second core 15. be. The second core 15 having the through holes 15N can be manufactured according to a conventionally known method for manufacturing an absorbent core. Typically, the second core 15 having the through holes 15N is formed on the outer peripheral surface of a rotating drum using a forming material supplied in an air stream. In the method of obtaining the second core 15 by suctioning and depositing the second core 15 in the accumulating recess, the portion corresponding to the through hole 15N at the bottom of the accumulating recess is larger than the peripheral portion of the rotating drum. It can be manufactured by using one that protrudes outward in the radial direction. In the second core 15 obtained by such a method, the portion where the forming material is not present is the through hole 15N.

As shown in FIGS. 2 and 4, in a region overlapping with the through hole 15N in plan view, the second sheet 12 and the intermediate sheet 13 are connected to the through hole non-formed portion 15M around the through hole 15N in the second core 15. They are closer than regions that overlap in plan view. That is, with reference to FIG. 5, the skin-facing surface of the second sheet 12 in a portion corresponding to the non-through-hole portion 15M, with the skin-facing surface of the second sheet 12 in the area overlapping with the through-hole 15N in plan view as a reference 12S. The separation distance along the thickness direction Z of the absorber 10 from the reference 12S is D1, and the separation distance along the thickness direction Z from the reference 12S of the non-skin facing surface of the portion of the intermediate sheet 13 corresponding to the non-through-hole portion 15M. When D2 is the separation distance D2, the separation distance D2 is shorter than the separation distance D1. Here, "close proximity" includes a state in which both sheets 12 and 13 are separated with a slight gap (typically a gap of 5 mm or less), and a state in which both sheets 12 and 13 are bonded with adhesive or the like. This includes a state in which they are in close contact with each other through a means or without a joining means. In addition, in FIG. 5, from the viewpoint of easy understanding, illustration of some of the constituent members of the absorber 10 shown in FIG. 4 (extending portion 12E of the second sheet 12, adhesives 21 to 25) is omitted.

In this embodiment, as shown in FIG. 4, the second sheet 12 and the intermediate sheet 13 are bonded to each other through adhesives 24 and 25 and are in close contact with each other in a region overlapping with the through hole 15N in plan view. The adhesive 24 is applied to the skin-facing surface of the intermediate sheet 13 (the surface opposite to the surface facing the first sheet 11), and the adhesive 25 is applied to the non-skin-facing surface of the second sheet 12 (the surface opposite to the surface facing the first sheet 11). 15 or the surface facing the intermediate sheet 13). Further, in this embodiment, the first sheet 11 and the extending portion 12E of the second sheet 12 are bonded together via the adhesive 21, and the intermediate sheet 13 and the second core 15 are bonded via the adhesive 24. There is. Since the constituent members of the absorbent body 10 are integrated through the adhesive in this way, the external shape of the absorbent body 10 is more stable, and predetermined performance can be more stably expressed. As the adhesives 21, 24, and 25, any adhesive that can be used for bonding members together in this type of absorbent article can be used without particular limitation, such as a hot melt adhesive. The amount and pattern of the adhesives 21, 24, and 25 to be applied are not particularly limited and can be set as appropriate.

Note that the second sheet 12 and the intermediate sheet 13 are joined in the entire region that overlaps the through hole 15N in a plan view, that is, the entire region does not need to be the joint between both sheets 12 and 13. , it is sufficient that they are joined in at least a portion of the region. That is, in the area overlapping with the through hole 15N in plan view, there are a portion where the second sheet 12 and the intermediate sheet 13 are in close contact with each other via the adhesives 24 and 25, and a portion where they are not in close contact but are close to each other. Can be mixed. It is preferable that the second sheet 12 and the intermediate sheet 13 are joined and in close contact with each other in at least 10% or more, more preferably 20% or more of the area overlapping with the through-hole 15N in plan view.

As described above, since the second core 15 of the absorbent body 10 has the through holes 15N, it has the effect of reducing discomfort when wearing an absorbent article including the absorbent body 10, and also has good liquid uptake properties. It has excellent liquid diffusibility and can significantly improve the liquid absorption performance of the absorbent article. However, on the other hand, there is a concern that the absorbent body 10 has the above-mentioned disadvantage due to having the through holes 15N, that is, the occurrence of unevenness on the outer surface of the absorbent article after liquid absorption, which is reminiscent of breakage of the absorbent body 10. be done. In contrast, in the present invention, the water-absorbing polymer occupancy (the proportion of the water-absorbing polymer relative to the total mass of the core-forming material) is The first core 14 having a content mass ratio of 90% by mass or more was arranged, and the water-absorbing polymer 20 was uniformly distributed at least in the region corresponding to the crotch part B of the first core 14.

In the absorbent body 10 having the above-described configuration, when the absorbent body 10 is in a liquid absorption state, as shown in FIG. It has recesses C1 and C2 on the surface side, and the depth C2D of the recess C2 on the non-skin facing surface side is 40% or less of the depth C1D of the recess C1 on the skin facing surface side. That is, in the absorbent state of the absorbent body 10, in a region overlapping with the through-hole 15N in the absorbent body 10 in plan view, "depth C1D of the concave portion C1 on the skin-facing surface side x 0.4 ≧ concave portion C2 on the non-skin-facing surface side". As a result, the non-skin facing surface of the absorbent body 10 (back sheet 4 side) has a depth C2D of The degree of unevenness (height difference between the top of the convex portion corresponding to the non-through-hole portion 15M and the bottom of the concave portions C1 and C2) is small. In this manner, when the absorbent body 10 is in a liquid-absorbing state, the non-skin-facing surface of the absorbent body 10 is in a state with relatively few irregularities, so that the outer surface (in this embodiment, the back sheet 4) of the diaper 1 being worn is This effectively prevents the inconvenience of unevenness that would cause the absorber 10 to break.

In the absorbent body 10, the water-absorbing polymer occupancy is 90% by mass or more and the water-absorbing polymer 20 is uniformly distributed on the non-skin-facing surface side of the second core 15 (the side close to the outer surface of the diaper 1). The first core 14 is arranged close to each other, and this first core 14 functions as a buffer material that suppresses swelling due to liquid absorption of the second core 15. Therefore, the non-skin facing surface side of the second core 15 is Swelling during liquid absorption is suppressed compared to the skin-facing surface side of the second core 15 where such a buffer material is not disposed close to the skin. Therefore, in the liquid absorbing state of the absorber 10, in the region overlapping with the through hole 15N in the absorber 10 in plan view, "depth C1D of the recess C1 on the skin-facing surface side x 0.4 ≧ recess on the non-skin-facing surface side" The size relationship "depth C2D of C2" is established.
In addition, in the liquid absorbing state of the absorbent body 10, the recess C2 is formed on the non-skin facing surface side in a region that overlaps with the through hole 15N in plan view. This is due to the difference in basis weight between the adjacent through hole non-formed portion 15M. That is, the second core 15 does not have a core forming material in the through hole 15N, but has a core forming material in the through hole non-forming part 15M adjacent to the through hole 15N, so the second core 15 does not absorb liquid. When the core forming material swells, only the portion of the first core 14 that corresponds to the through-hole-free portion 15M of the second core 15 is moved out of the thickness direction of the absorber 10 due to the swelling of the through-hole-free portion 15M. The portion of the first core 14 that corresponds to the through-hole 15N hardly receives any pressure due to the swelling of the second core 15. This difference in the pressing force of the second core 15 against the first core 14 during liquid absorption and swelling is one of the causes of the formation of the recess C2.

In the present invention, the "liquid absorption state of the absorber" refers to the state after the absorber is immersed in physiological saline for 30 minutes.

Referring to FIG. 5(b), the depth (maximum depth) C2D of the concave portion C2 on the non-skin facing surface side in the area overlapping the through hole 15N in the absorbent body 10 in the liquid absorbing state in plan view is The depth (maximum depth) C1D of the recess C1 on the surface side is 40% or less, preferably 35% or less, and more preferably 30% or less. Further, there is no particular restriction on the lower limit of such a ratio, and the lower the ratio (the closer it is to zero), the less likely unevenness will occur on the outer surface of the diaper 1 while it is being worn, which may be reminiscent of breakage of the absorbent body 10. Therefore, it is preferable.

From the viewpoint of more reliably preventing the occurrence of unevenness on the outer surface of the diaper 1 that would suggest breakage of the absorber 10 after liquid absorption, the depth of the recess C2 on the non-skin facing surface side in the area overlapping with the through hole 15N in plan view is determined. The depth (maximum depth) C2D (see FIG. 5(b)) is preferably less than 3 mm, more preferably less than 2.0 mm. There is no particular restriction on the lower limit of the depth C2D, and the closer it is to zero, the more preferable it is.

In the region overlapping with the through-hole 15N in plan view in the absorbent body 10 in a liquid-absorbing state, the depth C1D of the recess C1 on the skin-facing surface side x 0.4≧depth C2D of the recess C2 on the non-skin-facing surface side. From the viewpoint of more reliably establishing this size relationship, it is preferable that the absorbent core 10 has the following configuration A.
That is, with reference to FIG. 5, the skin-facing surface of the second sheet 12 in a portion corresponding to the non-through-hole portion 15M, with the skin-facing surface of the second sheet 12 in the area overlapping with the through-hole 15N in plan view as a reference 12S. The separation distance along the thickness direction Z of the absorber 10 from the reference 12S is D1, and the separation distance along the thickness direction Z from the reference 12S of the non-skin facing surface of the portion of the intermediate sheet 13 corresponding to the non-through-hole portion 15M. is D2, the separation distance D1 increases to a greater extent as the absorber 10 absorbs liquid than the separation distance D2 (configuration A).
5(a) shows the state of the absorbent body 10 before liquid absorption, and FIG. 5(b) shows the state of the absorbent body 10 before liquid absorption. The distances D1 and D2 between the states are denoted by symbols D2 a and D2b. The above-mentioned statement that "the separation distance D1 increases to a greater degree as the absorber 10 absorbs liquid than the separation distance D2" means that the magnitude of "(D1b-D1a)>(D2b-D2a)" It means that a relationship is established.
Note that the separation distance D1b from the reference 12S of the second sheet 12 of the portion corresponding to the through-hole non-formed portion 15M in the absorbent body 10 in the liquid-absorbing state is typically the same as that of the absorbent body 10 in the liquid-absorbing state. The depth (maximum depth) C1D of the recess C1 on the skin-facing surface side in the area overlapping with the through hole 15N in plan view coincides with the depth C1D.

From the viewpoint of more reliably preventing the occurrence of unevenness that may suggest breakage of the absorber 10 on the outer surface of the diaper 1 (in this embodiment, the non-skin facing surface of the backsheet 4) after liquid absorption, the absorber 10 is In the liquid absorption state, it is preferable that the separation distance D1 is longer than the separation distance D2. That is, referring to FIG. 5(b), it is preferable that the magnitude relationship of "separation distance D1b>separation distance D2b" holds true.

The difference between the separation distance D1a before liquid absorption and the separation distance D1b in the liquid absorption state, and the penetration in the intermediate sheet 13 for the portion corresponding to the non-through-hole portion 15M in the second sheet 12 The above (D2b-D2a) for the portion corresponding to the hole-free portion 15M, that is, the ratio of the difference between the separation distance D2a before liquid absorption and the separation distance D2b in the liquid absorption state (D1b-D1a)/(D2b-D2a) ) is preferably 1.1 or more, more preferably 1.2 or more, and preferably 10.0 or less, more preferably 5, on the premise that (D1b-D1a) is larger than (D2b-D2a). .0 or less.

From the viewpoint of balance between the thinning of the absorber 10 and various performances such as liquid absorption performance, the separation distance D1a (Fig. 5 (a ) is preferably 1.0 mm or more, more preferably 1.5 mm or more, and preferably 20 mm or less, more preferably 10 mm or less, provided that it is longer than the separation distance D2a.
From the same point of view, the separation distance D2a (see FIG. 5(a)) of the portion of the intermediate sheet 13 corresponding to the non-through-hole portion 15M is preferably 0.5 mm on the premise that it is shorter than the separation distance D1a. Above, it is more preferably 1.0 mm or more, and preferably 10 mm or less, and more preferably 5.0 mm or less.

From the viewpoint of more reliably preventing the occurrence of unevenness that may suggest breakage of the absorber 10 on the outer surface of the diaper 1 (in this embodiment, the non-skin facing surface of the backsheet 4) after liquid absorption, the absorber 10 is In the liquid absorption state, the thickness of the portion of the first core 14 corresponding to the through hole 15N (the portion that overlaps with the through hole 15N in plan view) is greater than that of the portion of the first core 14 corresponding to the through hole non-formed portion 15M. Preferably larger. That is, with reference to FIG. 5(b), the size relationship is "thickness T1 of the portion of the first core 14 corresponding to the through-hole non-formed portion 15M<thickness T2 of the portion of the first core 14 corresponding to the through-hole 15N". It is preferable that the following holds true.
The ratio between thickness T1 and thickness T2 is preferably 1.1 or more, more preferably 1.2 or more, and preferably 5.0 as thickness T 2 /thickness T 1 on the premise that thickness T1 < thickness T2. It is more preferably 3.0 or less.
The thickness T1 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and preferably 10 mm or less, more preferably 5 mm or less.
The thickness T2 is preferably 1.0 mm or more, more preferably 2.0 mm or more, and preferably 15 mm or less, more preferably 10 mm or less.

The dimensions of each part shown in FIG. 5 described above, that is, the depths C1D and C2D of the recesses C1 and C2, the separation distances D1 (D1a, D1b), D2 (D2a, D2b), and the thicknesses T1 and T2 of the absorber, respectively Measurement can be performed using an image analysis device (for example, Image-Pro (registered trademark) Plus, manufactured by Media Cybermetics) based on an image obtained by photographing a cross section along the thickness direction.
When measuring the dimensions of each part of the absorbent body 10 in a dry state before liquid absorption, for example, when measuring the separation distances D1a and D2a, the absorbent body 10 in that state is passed through the center of the region where the through hole 15N is formed. It is cut along an imaginary straight line extending in the horizontal direction Y, and the cut surface is photographed and measured by an image analysis device.
When measuring the dimensions of each part of the absorbent body 10 in a liquid-absorbing state, for example, when measuring the depths C1D, C2D, separation distances D1a, D2a, and thicknesses T1, T2, the absorbent body 10 in a dry state before liquid absorption is measured. On the other hand, 200 g of physiological saline was injected from the center of the area where the through hole 15N was formed on the second core 15 side, and after being allowed to stand still for 30 minutes, it passed through the center (the injection point of the physiological saline) in the lateral direction Y. A cut is made along an extending virtual straight line, and the cut surface is photographed and measured using an image analysis device.
The above-mentioned "formation region of the through hole 15N" is a region having the smallest area among the regions having a rectangular shape in a plan view that includes the through hole 15N. For example, in this embodiment, as shown in FIG. 3, a pair of through holes 15N having a rectangular shape in plan view are formed in the absorber 10 (second core 15), so the minimum area including the pair of through holes 15N is The rectangular region in plan view is the formation region of the through hole 15N. Therefore, when cutting the absorbent body 10 shown in FIG. Cut along an imaginary straight line extending to . In addition, when the absorber 10 shown in FIG. ) Inject saline into the center. Further, for example, when only one through hole 15N is formed in the absorbent body 10 (second core 15), the one through hole 15N itself is the formation area of the through hole 15N, so the absorbent body 10 is cut along an imaginary straight line extending in the horizontal direction Y through the center of the one through hole 15N. Inject saline.

In the liquid absorption state of the absorber 10, the above-mentioned size relationship of "depth C1D of the recess C1 on the skin-facing surface side x 0.4 ≧ depth C2D of the recess C2 on the non-skin-facing surface side" is established, and the present invention In order to achieve one of the main effects of ``not generating irregularities on the outer surface of the absorbent article that would suggest breakage of the absorbent body,'' it is necessary to It is necessary that the occupancy is 90% by mass or more, and that the distribution of the water-absorbing polymer 20 is uniform at least in the region corresponding to the crotch area B of the first core 14. In the region disposed at least in the crotch area B of the first core 14 where the water-absorbing polymer occupancy is 90% by mass or more, the water-absorbing polymer 20 is uniformly distributed, so that the region of the first core 14 is Swelling of the water-absorbing polymer 20 due to liquid absorption is suppressed, resulting in a region that is difficult to swell even when liquid is absorbed. Therefore, the first core 14 functions as a buffer material that can suppress the swelling of the non-skin facing surface side of the second core 15 (the first core 14 side), and ) can effectively prevent the formation of unevenness corresponding to swelling on the non-skin facing surface side of the second core 15.
The water-absorbing polymer occupancy of the first core 14 is at least 90% by mass or more, preferably 92% by mass or more, and more preferably 95% by mass or more. The water-absorbing polymer occupancy of the first core 14 may be 100% by mass.

In addition, in relation to the uniform distribution of the water-absorbing polymer 20 in the first core 14, a "laminated structure consisting of the first sheet 11, the first core 14, and the intermediate sheet 13" (hereinafter also referred to as "first core side laminated structure") ), where BR is the bending stiffness change rate per thickness change before and after liquid absorption calculated by the following formula (1), at least the area corresponding to the crotch part B of the first core 14 (i.e., the area corresponding to the crotch part B of the first core 14 In the area where the distribution of the water-absorbing polymer 20 of one core 14 is required to be uniform, the "vertical direction X", "lateral direction Y", and "diagonal direction D intersecting both directions X and Y" It is preferable that the BR in each of the three directions is 5.0/mm or less (BR≦5.0/mm holds true). The "diagonal direction D" here is typically a direction in which the angle with both directions X and Y is 45 degrees. More preferably, BR≦5.0/mm is satisfied in the three directions, not only in the region corresponding to the crotch portion B of the first core 14 but also in the entire first core 14.

BR=(B _w /B _d )/T0 _c (1)
B _w : Bending rigidity of the first core side laminated structure after liquid absorption B _d : Bending rigidity of the first core side laminated structure before liquid absorption T0 _c : First core side laminated structure calculated by the following formula (2) Amount of change in thickness before and after liquid absorption T0 _c = T0 _w - T0 _d (2)
T0 _w : Thickness of the first core side laminated structure after liquid absorption under 4.9 mN/cm ² loads T0 _d : Thickness of the first core side laminated structure before liquid absorption under 4.9 mN/cm ² loads Since the units of T0 _w and T0 _d are each [mm], the unit of T0 _c is also [mm], and therefore the unit of BR is [/mm].

In the first core side laminated structure, BR≦5.0/mm is satisfied in the three directions of the vertical direction This means that the increase in rigidity associated with liquid absorption is suppressed, that is, the value of (B _w /B _d ) is made relatively small, and it remains flexible even after liquid absorption.
In addition, BR is calculated by dividing the rate of change in bending rigidity of the first core-side laminate structure before and after liquid absorption by the amount of change in thickness of the first core-side laminate structure before and after liquid absorption, as shown in formula (1) above. Even if the amount of change in thickness is relatively large, that is, the degree of swelling of the first core 14 after liquid absorption is relatively large, if the rate of change in bending rigidity is relatively small, BR≦5 in the three directions. 0/mm may hold true. This means that in the first core side laminated structure in which BR≦5.0/mm can be established in the three directions, regardless of the degree of swelling of the first core 14 due to liquid absorption, the first core 14 This means that the water-absorbing polymer 20 is hard to get clogged inside, and the first core 14 is relatively soft and expands.
Therefore, the absorbent body 10 that satisfies BR≦5.0/mm in the three directions has suppressed the increase in rigidity due to liquid absorption and has excellent flexibility even after liquid absorption, so the diaper 10 equipped with the absorbent body 10 has excellent flexibility even after liquid absorption. The material does not give the wearer a stiff and uncomfortable feeling when worn, and has excellent wearing comfort not only before liquid absorption but also after liquid absorption.

In the absorbent body 10, the BR in each of the three directions of the first core side laminated structure is preferably at least 5.0/mm or less, more preferably 4.8/mm or less, still more preferably 4.5/mm, as described above. mm or less.
Further, the lower limit of the BR in each of the three directions of the first core side laminated structure is not particularly limited, but from the viewpoint of maintaining the minimum shape as an absorber, it is preferably 0.1/mm or more, more preferably 0. .3/mm or more.

Physical property values such as B _w used for calculating BR are not particularly limited, but from the viewpoint of more reliably achieving the predetermined effects of the present invention, it is preferable to set them as follows.
^The bending rigidity _Bw of the first core-side laminated structure after liquid absorption in the vertical direction /cm or less, more preferably 100 mN·cm ² /cm or less. The lower limit of B _w is not particularly limited, but from the viewpoint of ensuring the shape retention of the absorber 10, it is preferably 0.3 mN·cm ² /cm or more, more preferably 0.5 mN·cm ² /cm or more. be.
The bending rigidity B _d of the first core-side laminated structure before liquid absorption in the longitudinal direction cm ² /cm or less, more preferably 15 mN·cm ² /cm or less. The lower limit of B _d is not particularly limited, but from the viewpoint of ensuring the shape retention of the absorber 10, it is preferably 0.1 mN·cm ² /cm or more, more preferably 0.2 mN·cm ² /cm or more. be.
The thickness (maximum thickness) T0 _w of the first core side laminated structure after liquid absorption under a load of 4.9 mN/cm ² (=0.5 gf/cm ² ) is preferably 1 mm or more, more preferably 2 mm or more, The length is preferably 30 mm or less, more preferably 15 mm or less.
The thickness (maximum thickness) T0 _d of the first core side laminated structure before liquid absorption under a load of 4.9 mN/cm ² (=0.5 gf/cm ² ) is preferably 0.1 mm or more, more preferably 0 .3 mm or more, and preferably 5 mm or less, more preferably 3 mm or less.
The method of measuring the bending rigidity B _w , B _d and the thickness T0 _w , T0 _d of the first core-side laminated structure will be described later.

The fact that BR≦5.0/mm holds in each of the three directions (vertical direction X, horizontal direction Y, and diagonal direction D) of the first core side laminated structure means that the first core 14 of the first core side laminated structure This is possible by increasing the uniformity of the distribution of the water-absorbing polymer 20. In other words, when the water-absorbing polymer 20 is uniformly distributed over the entire predetermined water-absorbing polymer arrangement region in the first core 14, in the three directions of the first core-side laminated structure including the first core 14. BR≦5.0/mm can be established. In other words, the BR can be an index of the distribution state of the water-absorbing polymer in the first core-side laminated structure (first core 14).

As a specific example of the state in which the water-absorbing polymer is uniformly distributed, that is, the state in which BR≦5.0/mm is established in the three directions of the first core side laminated structure, the water-absorbing polymer arrangement In a plan view of the region (projected view in the thickness direction of the first core 14), the water-absorbing polymer 20 may be arranged in such a manner that no macroscopically visible gap is observed. Here, "no macroscopically visible gap is observed" means that when the area where the water-absorbing polymer 20 is arranged is viewed with the naked eye, the water-absorbing polymer 20 is located on one side of the first sheet 11 or the intermediate sheet 13. Although the water-absorbing polymers 20 are arranged so as to evenly cover the (inner surface), when looking microscopically at the arrangement area, it is acceptable that voids are unintentionally formed between the water-absorbing polymers 20. It is. This void is approximately 10 to 1000 μm in size. Further, the region in which the water-absorbing polymer 20 is disposed in the first core 14 is typically approximately the entire area of the first core 14 in a plan view (projection view in the thickness direction).

In this embodiment, as described above, the second core 15 has the through hole 15N (see FIG. 3, etc.), which reduces discomfort when wearing the diaper 1 and improves liquid uptake and diffusion. This effect is produced. If the water-absorbing polymer is uniformly distributed in the region overlapping in plan view with the through-hole 15N that provides such effects, the effects of the through-hole 15N can be more reliably achieved. Therefore, it is preferable that the water-absorbing polymer 20 is uniformly distributed in the region of the first core 14 that overlaps the through hole 15N in plan view. That is, it is preferable that BR≦5.0/mm be satisfied in the three directions of the region overlapping with the through hole 15N in plan view in the first core side laminated structure.

From the viewpoint of ensuring that the effects of BR≦5.0/mm are established in the three directions, that is, the water-absorbing polymer 20 is uniformly distributed in the first core 14, It is preferable that the ratio of B _w in two directions arbitrarily selected from the three directions is 0.8 or more and 1.2 or less, particularly 0.9 or more and 1.1 or less. For example, in the first core side laminated structure, "B _w in vertical direction X / B w in horizontal direction Y _" , "B _w in vertical direction X / B _w in diagonal direction D", and "B _w in horizontal direction Y / diagonal It is preferable that Bw _' ' in direction D is within the above range. Setting the ratio of _Bw in two directions arbitrarily selected from the three directions to 0.8 or more and 1.2 or less means that the water-absorbing polymer 20 constituting the first core 14 of the first core side laminated structure This is possible by increasing the uniformity of the distribution of

In the absorbent state of the absorbent body 10, the compressive deformation rate of the first core-side laminated structure, that is, the “laminated structure consisting of the first sheet 11, the first core 14, and the intermediate sheet 13” is the same as that of the “second sheet 12, the second core 15 and the intermediate sheet 13" (hereinafter also referred to as "second core side laminate structure"). The compression deformation rate indicates the ratio of the amount of displacement of the measurement target to the load pressure when the measurement target is compressed and deformed. means that it is easily deformed (easily compressed) when Compressive deformation rate is measured by the following method.

<Measurement method of compression deformation rate>
The compression deformation rate can be measured using, for example, Kato Tech Co. , Ltd.'s KES-G5 handy compression testing machine. A section of a certain size was cut out from the measurement target in a dry state (first core side laminated structure, second core side laminated structure), and the section was immersed in physiological saline in an amount 200 times the mass of the section for 30 minutes (absorbed). A laminated structure in a liquid state) is used as a sample. The sample is mounted on the test stand of a testing machine and compressed between steel plates with a circular plane with an area of 2 cm ² . The compression speed is 0.5 mm/sec, and the maximum compression load is 490 mN/cm ² (50 gf/cm ² ). When the thickness when loaded with 4.9 mN/cm ² (0.5 gf/cm ² ) is taken as thickness T0 (mm), and the thickness when loaded with 490 mN/cm ² (50 gf/cm ² ) is taken as thickness Tm (mm). , the compression deformation rate (%) can be calculated as “100×(T0−Tm)/T0”.

According to the findings of the present inventor, the absorbent body described in Patent Document 1 has a laminated structure of an upper layer absorbent body and a lower layer absorbent body, and an opening (through hole) is formed in the upper layer absorbent body. Due to the liquid dispersibility at the position where the openings are formed, there is room for improvement in leakage prevention, and body fluids such as urine leak outside through the gap between the upper absorbent layer and the lower absorbent layer. There is a risk of leakage. In contrast, the absorbent body 10 according to the present invention has a laminated structure of a second core 15 (upper layer absorbent body) and a first core 14 (lower layer absorbent body), and a through hole 15N is formed in the second core 15. However, as described above, since the water-absorbing polymer 20 is uniformly distributed in the first core 14, it is difficult to form a gap between the first core 14 and the second core 15, and the method described in Patent Document 1 Superior leak-proofing properties compared to absorbers. In addition to the uniform distribution of the water-absorbing polymer in the first core 14, in addition to the above-mentioned "compressive deformation rate of the first core side laminated structure>compressive deformation rate of the second core side laminated structure" in the absorbent state of the absorber 10. When this size relationship is established, the occurrence of a gap between the first core 14 and the second core 15 is further prevented, and the leak-proof performance can be further improved.

In the absorbent state of the absorbent body 10, the ratio of the compressive deformation rate of the first core side laminated structure and the compressive deformation rate of the second core side laminated structure is preferably 2 as former/latter, assuming that the former>latter. It is .0 or more, more preferably 2.3 or more, and preferably 10 or less, more preferably 5.0 or less.
In the absorbent state of the absorbent body 10, the compressive deformation rate of the first core side laminated structure is preferably 40% or more, more preferably 45%, on the premise that the compressive deformation rate of the first core side laminated structure is larger than the compressive deformation rate of the second core side laminated structure. or more, and preferably 80% or less, more preferably 75% or less.
In the absorbent state of the absorber 10, the compressive deformation rate of the second core side laminated structure is preferably 10% or more, more preferably 15%, on the premise that the compressive deformation rate of the second core side laminated structure is smaller than the compressive deformation rate of the first core side laminated structure. or more, and preferably 60% or less, more preferably 55% or less.
The compressive deformation rates of the first core-side laminated structure and the second core-side laminated structure in the liquid-absorbing state are determined by, for example, the distribution state of the water-absorbing polymer contained in the laminated structure, the content ratio of the water-absorbing polymer, and the laminated structure. The bonding state between the sheets or the sheets and the water-absorbing polymer, the bonding means used to form the bonding condition, and when using an adhesive as the bonding means, can be adjusted by adjusting the type of adhesive, basis weight, etc. It is.

To further explain the absorbent body 10, in the first core-side laminated structure, the first sheet 11 and the intermediate sheet 13 are bonded via adhesives 22 and 23. As an example of the joining form of both sheets 11 and 13, as shown in FIG. , a configuration in which both sheets 11 and 13 are joined is exemplified. In such a joining form via the columnar portion 26, both sheets 11 and 13 are not in close contact with each other but are in a state in which they are close to each other with a predetermined interval. Typically, the columnar portions 26 are arranged regularly or in the area where the adhesives 22 and 23 are applied (the area where the water-absorbing polymer 20 is present) in a plan view (projected view in the thickness direction) of the first core-side laminated structure. Multiple irregularly scattered dots are formed. The plurality of columnar parts 26 may have the same height (length in the thickness direction of the first core 14) or may have different heights. The plurality of columnar parts 26 include those that are bonded to the water-absorbing polymer 20 interposed between both sheets 11 and 13 (those that are bonded to both sheets 11 and 13 and the water-absorbing polymer 20, respectively), and those that are bonded to the water-absorbing polymer 20. There may be a mixture of sheets that are not joined together (those that are joined only to both sheets 11 and 13). The formation of the columnar portions 26 can be controlled by appropriately adjusting the type and amount of adhesive used, the basis weight and particle size of the water-absorbing polymer 20 interposed between the sheets 11 and 13.

In addition, in the first core side laminated structure, as shown in FIG. There may be cases where portions 16 that are in close contact with each other via adhesives 22 and 23 coexist. In addition, in FIG. 6(b), the contact portion 16 between the sheets 11 and 13 is formed in a region that overlaps the through hole 15N in plan view, but the location where the contact portion 16 is formed is not particularly limited. A plurality of dots may be formed regularly or irregularly in the area where the adhesives 22 and 23 are applied (the area where the water-absorbing polymer 20 is present). However, from the viewpoint of ensuring that the water-absorbing polymer 20 is uniformly distributed in the first core 14, such a close contact portion 16 between the sheets 11 and 13 does not exist or does not exist. It is also preferable that the amount is also small.

As the adhesive that facilitates the formation of the columnar portions 26, it is preferable to use an adhesive that has flexibility so that it can expand following the swelling changes caused by the absorption of liquid by the water-absorbing polymer 20. Examples of such raw materials include (co)polymers of vinyl monomers such as 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate, cyanoacrylate, vinyl acetate, methyl methacrylate, etc. (ethylene vinyl acetate copolymers, etc.) ), silicone adhesives containing polydimethylsiloxane polymers, natural rubber adhesives containing natural rubber, polyisoprene, chloroprene, etc. Isoprene adhesives, styrene-butadiene copolymer (SBR), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butadiene-styrene block copolymer Examples include rubber adhesives such as styrene adhesives containing one or more of polymer (SEBS) and styrene-ethylene-propylene-styrene block copolymer (SEPS). These may be used alone or in combination of two or more.

Among these adhesives, adhesives are excellent in flexibility and elasticity, maintain the bonded state between the first sheet 11 and the intermediate sheet 13 even after the water-absorbing polymer 20 has swelled, and exhibit shrinkage force. From the viewpoint of easily holding the water-absorbing polymer 20 between the sheets 11 and 13, it is preferable to use a rubber adhesive as the adhesive 22 and 23 used for the first core 14. Among these, it is more preferable to use a styrene adhesive.

From the viewpoint of achieving both flexibility of the adhesive and adhesiveness to the sheet, the adhesives 22 and 23 used for the first core 14 are preferably hot melt adhesives. Hot melt adhesives include, for example, the various adhesives mentioned above, tackifiers such as petroleum resins and polyterpene resins, plasticizers such as paraffin oil, and, if necessary, phenol-based, amine-based, phosphorus-based, etc. It may contain an antioxidant such as benzimidazole.

The adhesives 22 and 23 used for the first core 14 have a relaxation time determined by viscoelasticity measurement at 50° C. of preferably 1 second or more, more preferably 2 seconds or more, and still more preferably 3 seconds or more. Since the adhesives 22 and 23 have such values, they exhibit appropriate flexibility and elasticity, and even after the water-absorbing polymer 20 has swelled, the first sheet 11 and the intermediate sheet 13 can be bonded together. This state is maintained, making it possible to hold the water-absorbing polymer 20 between the sheets 11 and 13.

The relaxation time at 50° C. of the adhesive obtained by viscoelasticity measurement is calculated as the reciprocal of the value of tanθ obtained when the dynamic viscoelasticity of the adhesive is measured under the following conditions. In detail, a rotary rheometer (manufactured by Anton Paar, model "Physica MCR301") is used, and a receiving plate having a circular shape in a plan view that supports the measurement sample from below, and a flat surface facing above the receiving plate are used. Adhesives to be measured (adhesives 22 and 23) are interposed between the press plate and the circular pressing plate. The adhesive in this state has a circular shape in plan view, and has a thickness of 1.5 mm and a diameter of 12 mm. The measurement frequency is set to 1 Hz, the strain amplitude is set to 0.05%, and the cooling rate is set to 2°C/min, and the measurement is performed in a temperature range from 120°C to -10°C. tanθ is the value obtained by dividing the loss modulus G'' by the storage modulus G'.

In this embodiment, as shown in FIG. 4, the adhesive 25 is applied to the skin-facing surface of the second core 15 (the surface facing the second sheet 12), and the non-skin-facing surface of the second core 15 ( An adhesive 24 is applied to the surface facing the intermediate sheet 13), and the second core 15 is joined to both sheets 11 and 13 via the adhesives 24 and 25. From the viewpoint of more reliably achieving one of the main effects of the present invention, ie, "not generating irregularities on the outer surface of the absorbent article that would suggest breakage of the absorbent body," the second core 15 is It is preferable that the adhesive 24 on the skin-facing surface has a larger application amount (basis weight) per unit area than the adhesive 25 on the skin-facing surface of the second core 15 . By establishing the magnitude relationship "Basic weight of the adhesive 24 on the non-skin facing side of the second core 15>Basic weight of the adhesive 25 on the skin facing side of the second core 15", the intermediate sheet 13 is Since the adhesion between the first core 14 and the second core 15 sandwiched between the two cores is further improved, the water-absorbing polymer 20 is uniformly distributed at least in the region corresponding to the crotch area B of the first core 14 described above. Coupled with the resulting effects, the main effects of the present invention can be achieved even more reliably.

The ratio of the basis weight of the adhesive 24 on the non-skin-facing side of the second core 15 to the basis weight of the adhesive 25 on the skin-facing side of the second core 15 is calculated as the former/latter, assuming that the former>the latter. , preferably 1.1 or more, more preferably 1.3 or more, and preferably 15 or less, more preferably 10 or less.
The basis weight of the adhesive 24 is preferably 3.0 g/m ² or more, more preferably 4.5 g/m ² or more, and preferably 40 g/m ² or less, more preferably 20 g/m ² or less.
The basis weight of the adhesive 25 is preferably 1.3 g/m ² or more, more preferably 1.5 g/m ² or more, and preferably 35 g/m ² or less, more preferably 15 g/m ² or less.
Note that the basis weight of the adhesive herein refers to the amount of adhesive applied per unit area of the area to which the adhesive is applied (specifically, for example, the non-skin facing surface or the skin facing surface of the second core 15). It is. Therefore, for example, if an area to be coated has a mixture of adhesive-applied areas and non-applied areas due to intermittent application of adhesive, the basis weight of the adhesive in the area to be applied will be the basis weight of the adhesive-unapplied areas. be.

In this embodiment, as described above, as shown in FIG. 4, the second sheet 12 and the intermediate sheet 13 are joined in the region overlapping with the through hole 15N in plan view, which is one of the main effects of the present invention. In order to more reliably achieve the goal of "not creating irregularities on the outer surface of the absorbent article that would suggest breakage of the absorbent body," the intermediate sheet 13 and the first sheet 11 are further bonded. It is preferable that Here, the intermediate sheet 13 and the first sheet 11 are joined in the entire region that overlaps with the through hole 15N in plan view. In other words, it is not necessary that the entire region is a joint between both sheets 12 and 11. It is sufficient that the area is bonded in at least a portion of the area. That is, in the area overlapping with the through hole 15N in plan view, there are a portion where the intermediate sheet 13 and the first sheet 11 are in close contact with each other via the adhesives 22 and 23, and a portion where they are not in close contact but are close to each other. Can be mixed. It is preferable that the intermediate sheet 13 and the first sheet 11 are joined and in close contact with each other in at least 10% or more, more preferably 30% or more of the area overlapping with the through hole 15N in plan view.

From the same point of view, regarding the amount of adhesive applied per unit area (basis weight) on one side of each of the first sheet 11, second sheet 12, and intermediate sheet 13, "intermediate sheet 13>first sheet 11≧th It is preferable that the size relationship between the two sheets 12 is satisfied. That is, the basis weight of the adhesive on one surface (the skin-facing surface or the non-skin-facing surface) is the highest in the intermediate sheet 13, and both sheets 11 and 12 are the same, or the first sheet 11 is the same as the second sheet. It is preferable that the number of sheets is larger than that of the sheet 12.

In order to more reliably achieve the predetermined effects of the present invention, it is preferable that the first core 14 has a smaller basis weight (mass per unit area) of the water-absorbing polymer than the second core 15. preferable. That is, regarding the basis weight of the water-absorbing polymer, it is preferable that the magnitude relationship "first core 14<second core 15" holds true. In addition, the "basis weight of the water-absorbing polymer" herein refers to the basis weight of the water-absorbing polymer in the portion other than the portion where the core forming material does not exist, such as the through hole 15N. means.

The ratio of the basis weight of the water-absorbing polymer of the first core 14 and the basis weight of the water-absorbing polymer of the second core 15 is preferably 1.1 or more, more preferably 1.1 or more as the latter/former, assuming that the former < the latter. It is 1.3 or more, preferably 10.0 or less, and more preferably 5.0 or less.
The basis weight of the water-absorbing polymer of the first core 14 is preferably 60 g/m ² or more, more preferably 80 g/m ² or more, and preferably 700 g/m ² or less, more preferably 500 g/m ² or less. .
The basis weight of the water-absorbing polymer of the second core 15 is preferably 65 g/m ² or more, more preferably 70 g/m ² or more, and preferably 800 g/m ² or less, more preferably 600 g/m ² or less. .

In this embodiment, the absorber 10 has a long shape in one direction in plan view, as shown in FIG. In this embodiment, the absorbent body 10 has a long shape in the longitudinal direction X of the diaper 1, specifically a rectangular shape, and the longitudinal direction of the absorbent body 10 coincides with the longitudinal direction The width direction coincides with the horizontal direction Y. Further, the first core 14 and the second core 15 (intermediate sheet 13) also have a long shape in the vertical direction X. In this embodiment, the shape of the second core 15 in plan view is substantially the same as that of the intermediate sheet 13.

In this embodiment, as shown in FIG. With the vertical center line CLx as a boundary, one side (left side in FIG. 3) of the absorbent body 10 in the longitudinal direction (longitudinal direction 3 has more water-absorbing materials (water-absorbing polymers, water-absorbing fibers, etc.) than the right side). Typically, almost all of the core-forming material of the absorbent body 10, specifically, for example, 100% by mass of the total mass of the core-forming material, is a water-absorbing material. If the water-absorbing material is unevenly distributed in a part of the absorbent material, the uneven distribution of the water-absorbing material is reflected in the external shape of the absorbent body 10 as shown in FIG. Therefore, when almost all of the core forming material is a water-absorbing material, "there is more water-absorbing material on one longitudinal side of the absorbent body 10 than on the other longitudinal side of the absorbent body 10" as described above. "Water-absorbing material" can be translated into "core-forming material."

Examples of uneven distribution of the water absorbent material (core forming material) in the absorbent body 10 described above include: 1) In the first core 14, the water absorbent material is unevenly distributed on one side in the longitudinal direction (vertical direction X); 2) In the second core 15, the water-absorbing material is unevenly distributed on one side in the longitudinal direction (vertical direction X), and in the first core 14, the water-absorbing material is uniform. 3) A form in which the water-absorbing material is unevenly distributed on one side in the longitudinal direction (vertical direction The material is unevenly distributed on one side in the longitudinal direction (vertical direction X), and the water absorbent material is unevenly distributed on the other side in the longitudinal direction (vertical direction Examples include a form in which the water-absorbing material is unevenly distributed on one side in the direction (X). Note that "the water-absorbing material (core-forming material) is uniformly present" refers to the macroscopic observation of the first core 14 or the second core 15 or the absorbent body 10 (for example, the macroscopic observation of the first core 14, etc.). This refers to a state in which the water-absorbing material (core forming material) is found to be evenly distributed throughout the microscopic observation of a portion of the first core 14 (e.g., the first core 14, etc.). Uniformity in the strict sense, which can be confirmed for the first time through microscopic observation of a cross section of the material, is not a problem.

In this embodiment, as shown in FIG. 3, the form 2) above is adopted as the form of uneven distribution of the water-absorbing material (core forming material). That is, the second core 15 extends across the center (vertical center line CLx of the absorbent body 10) in the longitudinal direction (longitudinal direction The portion of the second core 15 located on the other side of the longitudinal direction (vertical direction X) of the absorber 10 (the right side in FIG. ), there are more water-absorbing materials (core forming materials). On the other hand, in the first core 14, the water-absorbing material (core forming material) is uniformly present.

Further, in the present embodiment, as shown in FIG. 3, the portion of the second core 15 located on one side (the left side in FIG. 3) of the absorber 10 in the longitudinal direction (vertical direction The area of the main surface is larger than that of the portion located on the other side (the right side in FIG. 3) of the absorber 10 in the longitudinal direction (vertical direction X). The "principal surface" here means the surface with the largest area in the second core 15, and is usually the liquid-receiving surface that first comes into contact with the liquid to be absorbed or the surface opposite to the liquid-receiving surface. Yes, or a skin-facing surface or a non-skin-facing surface. Note that this definition of the main surface is also applied to other members such as the first core 14 and the absorbent body 10, unless otherwise specified.

To explain further, in plan view as shown in FIG. 3, the first core 14 (intermediate sheet 13) has a rectangular shape and has a larger main surface area than the second core 15. It is arranged so as to fit within a region surrounded by the periphery of the first core 14 (intermediate sheet 13), and does not extend outward beyond the periphery of the first core 14.
The second core 15 has a shorter length in the longitudinal direction (vertical direction X) than the first core 14 (intermediate sheet 13), and the length of the second core 15 in the longitudinal direction The ratio is preferably 1.05 or more, more preferably 1.1 or more, and preferably 1.7 or less, more preferably 1.6 or less, on the premise that former<latter.
Further, the length (width) in the width direction (horizontal direction Y) is not constant over the entire length in the longitudinal direction, and the second core 15 has a wide portion 15A that is relatively wide and has a large main surface area, and a wide portion 15A that is relatively wide and has a large main surface area. It has a narrow portion 15B having a narrow principal surface area in the longitudinal direction (vertical direction X).
The width (length in the lateral direction Y) of the wide portion 15A near the narrow portion 15B gradually decreases toward the narrow portion 15B.
The second core 15 is disposed at the peripheral edge of the surface of the intermediate sheet 13 on which the second core 15 is disposed (in this embodiment, the skin-facing surface of the intermediate sheet 13), particularly on the outer side of the narrow portion 15B in the lateral direction Y. There is a portion where the intermediate sheet 13 is exposed, and at this exposed portion of the intermediate sheet 13, the intermediate sheet 13 and the second sheet 12 are joined via adhesives 24 and 25 (see FIG. (see 4).

The ratio of the maximum length (maximum width) in the lateral direction Y of the wide portion 15A to the maximum width of the narrow portion 15B is preferably 1.1 or more, more preferably 1.2 or more as the former/latter, and It is preferably 5.5 or less, more preferably 3.0 or less.
The ratio of the length of the wide portion 15A in the longitudinal direction X to the length of the narrow portion 15B in the longitudinal direction X is preferably 1.2 or more , more preferably 1.5 or more, and preferably is 7.0 or less, more preferably 5.0 or less.

In the present embodiment, as shown in FIG. 1, the side of the absorbent body 10 where the water-absorbing material (core forming material) is unevenly distributed in the longitudinal direction, that is, the wide portion 15A side of the second core 15 is the side of the diaper 1. It is arranged so as to be located closer to the abdominal part A. In the absorbent body 10 as a constituent member of the diaper 1, the body fluid to be absorbed usually concentrates in a specific location, specifically, in the crotch area B or the central part in the longitudinal direction X of the diaper 1, or in addition to these. Since the liquid is concentrated in the area near the crotch area B in the abdominal part A, the portion of the absorbent body 10 where a relatively large amount of water-absorbing material (core forming material) exists is located in the area where these liquids are concentrated. , it is preferable to arrange the absorber 10. By doing so, it becomes possible to achieve both liquid absorption performance and thinning of the absorber 10.

Regarding the Klemm water absorption height measured according to JIS P8141, the magnitude relationship of "first sheet 11 ≦ second sheet 12 < intermediate sheet 13" is established, and the Klemm water absorption height of the intermediate sheet 13 is 5 minutes. It is preferably 20 mm or more , and more preferably 25 mm or more. Establishment of the above-mentioned size relationship is mainly effective in increasing the utilization efficiency of the water-absorbing polymer 20 of the first core 14 by quickly absorbing liquid and diffusing it in the surface direction. Having the height within the above range is mainly effective in increasing the dispersibility of the liquid in the surface direction. Therefore, the absorbent body 10 that satisfies these requirements has particularly excellent liquid absorption performance. The Klem water absorption height is an index of liquid retention, and the higher the KREM water absorption height, the higher the liquid retention of the fiber sheet.

Crepe paper is particularly preferable as the intermediate sheet 13 from the viewpoint of establishing the above-mentioned size relationship regarding crepe water absorption height. Crepe paper may be used as the first sheet 11 and the second sheet 12. Crepe paper is paper that has pleats or wrinkles. The folds and wrinkles give the paper elasticity, so when stretched, crepe paper has a larger surface area than regular paper. Due to such characteristics of crepe paper, the intermediate sheet 13 etc. made of crepe paper has a relatively high Creme water absorption height, therefore has excellent liquid drawing ability, and has relatively low rigidity in the liquid absorption state. . The degree of crepe in the crepe paper is preferably 5% or more, more preferably 10% or more, still more preferably 15% or more, and 30% or less, expressed as a crepe rate measured by an underwater elongation method. Be realistic.

A preferable example of the intermediate sheet 13 is crepe paper having a crepe rate within the above-mentioned preferable range.
On the other hand, the second sheet 12 preferably has a crepe rate of less than 1%. By setting the second sheet 12 to such a crepe rate, it is possible to make the crepe water absorption height of the second sheet 12 lower than that of the intermediate sheet 13, and also to prevent liquid from entering the inside of the second sheet 12. It is possible to improve air permeability by making it difficult to retain the material.
The crepe rate of the first sheet 11 may be in the same range as that of the second sheet 12.

The crepe rate can be measured by the underwater elongation method, for example, based on the following method. Measurements are performed at 23±2° C. and relative humidity of 50±5%, and samples are stored in the same environment for at least 24 hours before measurement. A measurement sample was prepared by cutting the sheet to be measured into a size of 25 mm in the direction in which the wrinkles extend and 100 mm in the direction perpendicular thereto, and the measurement sample was immersed in water for 1 minute and then pulled out. The crepe rate is calculated from the amount of change in dimension in the orthogonal direction using the following formula. The measurement was performed three times, and the arithmetic mean value was taken as the crepe rate (%). If it is not possible to secure a size of 100 mm in the orthogonal direction, the crepe rate can be determined by cutting to a size of at least 30 mm or more in the orthogonal direction.
Crepe rate (%) = {(Dimensions after immersion in water (mm))/(Dimensions before immersion in water (mm)) -1} x 100

A preferred embodiment of the first sheet 11 is a nonwoven fabric, more preferably an SMS nonwoven fabric.
As a preferred embodiment of the second sheet 12, one that includes a nonwoven fabric can be exemplified. More specifically, examples include spunbond nonwoven fabrics and SMS nonwoven fabrics, with SMS nonwoven fabrics being particularly preferred.
As a preferred embodiment of the intermediate sheet 13, paper mainly composed of cellulose fibers (the content of cellulose fibers is 50% by mass or more) can be exemplified.

The basis weight of the first sheet 11 is preferably 5 g/m ² or more, more preferably 8 g/m ² or more, and preferably 80 g/m ² or less, more preferably 60 g/m ² or less.
The basis weight of the second sheet 12 is preferably 5 g/m ² or more, more preferably 8 g/m ² or more, and preferably 80 g/m ² or less, more preferably 60 g/m ² or less.
The basis weight of the intermediate sheet 13 is preferably 5 g/m ² or more, more preferably 8 g/m ² or more, and preferably 80 g/m ² or less, more preferably 60 g/m ² or less.

The basis weight of the first core side laminated structure, that is, "the laminated structure consisting of the first sheet 11, the first core 14, and the intermediate sheet 13" is not particularly limited, but from the viewpoint of the balance between absorption capacity, thinning, and flexibility. , preferably 80 g/m ² or more, more preferably 100 g/m ² or more, and preferably 600 g/m ² or less, more preferably 400 g/m ² or less.
From the same viewpoint, the basis weight of the second core 15 (the basis weight of the portion other than the through hole 15N described later) is preferably 100 g/m ² or more, more preferably 150 g/m ² or more, and preferably 800 g/m 2 or more. m ² or less, more preferably 700 g/m ² or less.

The absorbent body 10 can be manufactured according to a conventional method using a known device. The manufacturing apparatus for the absorbent body 10 typically includes a first manufacturing section that manufactures the first core 14 and a second manufacturing section that manufactures the second core 15. The second manufacturing section typically includes the above-mentioned fiber stacking device. The first manufacturing section typically includes a sheet conveyance means, an application means for applying an adhesive to the sheet, and a water-absorbing polymer 20 dispersion means. In the first manufacturing department, while the conveyance means conveys either the first sheet 11 or the intermediate sheet 13, the application means coats an adhesive in a predetermined pattern on one side of the sheet being conveyed. Then, after the water-absorbing polymer 20 is sprayed by the spraying means onto the area where the adhesive is applied on the sheet being conveyed, the other of the two sheets 11 and 13 is sprayed with the water-absorbing polymer 20 on one of the sheets. The first core 14 is manufactured by superimposing the first core 14 on its surface, integrating it via the adhesive, and cutting it into product unit lengths as necessary.

In the manufacturing apparatus for the absorbent body 10, the second core 15 manufactured in the second manufacturing section is placed on the adhesive-coated surface of the second sheet 12, which has been previously coated with adhesives 21 and 25. While being conveyed together with the second sheet 12, the first core 14 manufactured in the first manufacturing section is superimposed on the second core 15 being conveyed, and an adhesive that has been applied in advance to at least one of both cores 14 and 15 is applied. 24, the extended portion 12E (see FIG. 4) of the second sheet 12 is wrapped around the first core 14 to cover it, and cut into product unit lengths as necessary. By doing so, the absorber 10 is manufactured.

The absorbent article of the present invention is not limited to the expandable disposable diaper as in the above embodiment, but broadly includes articles used for absorbing body fluids (urine, menstrual blood, soft stool, sweat, etc.) discharged from the human body, It also includes pants-type disposable diapers, sanitary napkins, sanitary shorts, etc. that do not have a fastening structure such as the fastening member 8 and the fastening region 9.

Although the present invention has been described above based on its preferred embodiments, the absorbent article of the present invention is not limited to the above embodiments and can be modified as appropriate.
For example, in the embodiment, other members are not interposed between the second core 15 and the second sheet 12 and the intermediate sheet 13; A permeable or liquid-absorbing member may be interposed between the two cores 15 and the intermediate sheet 13. As an example of such a configuration, the skin-facing surface and/or non-skin-facing surface of the second core 15 may be covered with a liquid-permeable or liquid-absorbent sheet that is separate from the second sheet 12 and the intermediate sheet 13. Can be mentioned.
Further, in the embodiment, the first sheet 11, the second sheet 12, and the intermediate sheet 13 were each separate and independent members, but any two of them constitute one sheet. You can leave it there. As a specific example, the absorber 10 includes one sheet that covers the skin-facing surface (the second core 15 side) and the non-skin-facing surface (the side opposite to the second core 15 side) of the first core 14. , the portion of the one sheet that covers the non-skin facing surface of the first core 14 is the first sheet 11, and the portion of the one sheet that covers the skin facing surface of the first core 14 is the intermediate sheet 13. One example is the form. As another specific example, the absorber 10 may include one sheet that covers the skin-facing surface (the side opposite to the first core 14 side) and the non-skin-facing surface (the first core 14 side) of the second core 15. The portion of the one sheet that covers the non-skin facing surface of the second core 15 is the intermediate sheet 13, and the portion of the one sheet that covers the skin facing surface of the second core 15 is the second sheet 12. There is a certain form.

Further, the plan view shape and number of the through holes 15N are not limited to those in the embodiment described above, and can be set arbitrarily. For example, one through hole 15N having a rectangular shape in a plan view may extend in the vertical direction X at the center of the second core 15 in the horizontal direction Y, or a plurality of three or more through holes having a rectangular shape in a plan view The through holes 15N may be arranged intermittently in the horizontal direction Y with their longitudinal directions aligned with the vertical direction X.
In addition, in the absorbent article of the present invention, from the viewpoint of improving absorbency and leak-proofing properties, a second sheet, a sublayer sheet, etc., is provided between the top sheet 3 and the absorbent body 10 (second sheet 12). A liquid permeable sheet made of paper or various nonwoven fabrics may be interposed.
All parts that only one of the embodiments described above has can be used mutually as appropriate. Regarding the embodiments of the present invention described above, the following additional notes are further disclosed.

<1>
It has a vertical direction corresponding to the front and back direction of the wearer and a horizontal direction perpendicular to the longitudinal direction, and has a crotch area located in the wearer's crotch area and a crotch area located on the ventral side of the wearer from the crotch area. An absorbent article for use in an absorbent article comprising: a ventral side portion;
an intermediate sheet, a first sheet disposed on the non-skin facing surface side of the intermediate sheet, and a second sheet disposed on the skin facing surface side of the intermediate sheet, the first sheet and the intermediate sheet A first core containing at least a water-absorbing polymer as a water-absorbing material is interposed between the intermediate sheet and the second sheet, and a water-absorbing second core that swells by liquid absorption is interposed between the intermediate sheet and the second sheet. It is located
A through hole passing through the second core in the thickness direction is formed in a region corresponding to the crotch portion of the second core, and in a region overlapping with the through hole in a plan view, the second sheet and the intermediate sheet is closer than a region of the second core that overlaps the through-hole non-formed portion around the through-hole in a plan view,
90% by mass or more of the material forming the first core is a water-absorbing polymer,
In a region corresponding to the crotch portion of the first core, the water-absorbing polymer is uniformly distributed;
In a liquid absorbing state, the absorbent body has recesses on the skin-facing surface side and the non-skin-facing surface side in a region that overlaps with the through-hole in plan view, and the depth of the recesses on the non-skin-facing surface side is equal to or greater than the skin-facing surface. The absorber has a depth of 40% or less of the recess on the opposing surface side.
<2>
In a region of the absorbent body in a liquid-absorbing state that overlaps with the through-hole in plan view, the depth (maximum depth) of the recess on the non-skin facing surface side is equal to the depth (maximum depth) of the recess on the skin facing surface side. The absorbent according to <1> above, wherein the absorbent content is preferably 35% or less, more preferably 30% or less.
<3>
The absorbent body according to <1> or <2>, wherein the depth (maximum depth) of the recess on the non-skin facing surface side in the region overlapping with the through hole in plan view is less than 3 mm.
<4>
Any one of <1> to <3> above, wherein the depth (maximum depth) of the recess on the non-skin facing surface side in a region overlapping with the through hole in plan view is preferably less than 2.0 mm. Absorber described in.

<5>
Based on the skin-facing surface of the second sheet in a region overlapping with the through-hole in plan view, along the thickness direction of the skin-facing surface of the portion of the second sheet corresponding to the non-through-hole portion from the reference. When the separation distance is D1, and the separation distance along the thickness direction from the reference of the non-skin facing surface of the portion of the intermediate sheet corresponding to the non-through-hole formed portion is D2, the separation distance D1 is greater than the non-skin-facing surface of the intermediate sheet. The absorbent body according to any one of <1> to <4>, wherein the degree of increase due to liquid absorption by the absorbent body is greater than the separation distance D2.
<6>
The absorbent body according to <5>, wherein the separation distance D1 (D1b) is longer than the separation distance D2 (D2b) in the liquid absorption state of the absorbent body.
<7>
Regarding the separation distance D1, the state of the absorber before absorbing liquid is D1a, the state of the absorber in a liquid absorbing state is D1b, and regarding the separation distance D2, the state of the absorber before absorbing liquid. is D2a, and the liquid absorption state of the absorber is D2b, then the difference between the separation distance D1a and the separation distance D1b (D1b - D1a) with respect to the difference between the separation distance D2a and the separation distance D2b (D2b - D2a) The absorber according to <5> or <6>, wherein the ratio of (D1b-D1a)>(D2b-D2a) is preferably 1.1 or more, more preferably 1.2 or more.
<8>
Regarding the separation distance D1, the state of the absorber before absorbing liquid is D1a, the state of the absorber in a liquid absorbing state is D1b, and regarding the separation distance D2, the state of the absorber before absorbing liquid. is D2a, and the liquid absorption state of the absorber is D2b, then the difference between the separation distance D1a and the separation distance D1b (D1b - D1a) with respect to the difference between the separation distance D2a and the separation distance D2b (D2b - D2a) In any one of the above items <5> to <7>, the ratio of (D1b-D1a)>(D2b-D2a) is preferably 10.0 or less, more preferably 5.0 or less. Absorber as described.
<9>
In the state before liquid absorption of the absorber, the separation distance D1 (D1a) is preferably 1.0 mm or more, more preferably 1.5 mm or more, on the premise that the separation distance D1 (D1a) is longer than the separation distance D2 (D2a). The absorber according to any one of <5> to <8> above.
<10>
In the state before liquid absorption of the absorber, the separation distance D1 (D1a) is preferably 20 mm or less, more preferably 10 mm or less, on the premise that the separation distance D1 (D1a) is longer than the separation distance D2 (D2a). The absorber according to any one of items 5> to <9>.
<11>
In the state before liquid absorption of the absorber, the separation distance D2 (D2a) is preferably 0.5 mm or more, more preferably 1.0 mm or more, on the premise that the separation distance D2 (D2a) is shorter than the separation distance D1 (D1a). The absorber according to any one of <5> to <10> above.
<12>
In the state before liquid absorption of the absorber, the separation distance D2 (D2a) is preferably 10 mm or less, more preferably 5.0 mm or less, on the premise that it is shorter than the separation distance D1 (D1a). The absorbent body according to any one of <5> to <11>.

<13>
<1> to above, wherein the thickness of the portion of the first core corresponding to the through-hole is greater than the portion of the first core corresponding to the non-through-hole formed portion in the liquid absorption state of the absorber; The absorber according to any one of <12>.
<14>
The ratio of the thickness (T1) of the portion of the first core corresponding to the through-hole-free portion and the thickness (T2) of the portion of the first core corresponding to the through-hole is premised on the former < the latter. The absorber according to <13> above, wherein the latter / former ratio is preferably 1.1 or more, more preferably 1.2 or more.
<15>
The ratio of the thickness (T1) of the portion of the first core corresponding to the through-hole-free portion and the thickness (T2) of the portion of the first core corresponding to the through-hole is premised on the former < the latter. The absorber according to <13> or <14>, wherein the latter / former ratio is preferably 5.0 or less, more preferably 3.0 or less.
<16>
Any one of <13> to <15> above, wherein the thickness (T1) of the portion of the first core corresponding to the non-through-hole portion is preferably 0.5 mm or more, more preferably 1.0 mm or more. The absorbent body according to item 1.
<17>
According to any one of <13> to <16>, wherein the thickness (T1) of the portion of the first core corresponding to the non-through-hole portion is preferably 10 mm or less, more preferably 5 mm or less. absorber.
<18>
In any one of <13> to <17> above, the thickness (T2) of the portion of the first core corresponding to the through hole is preferably 1.0 mm or more, more preferably 2.0 mm or more. Absorber as described.
<19>
The absorbent body according to any one of <13> to <18>, wherein the thickness (T2) of the portion of the first core corresponding to the through hole is preferably 15 mm or less, more preferably 10 mm or less. .

<20>
The bending rigidity change rate per thickness change before and after liquid absorption, calculated by the following formula (1), of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet. In the case of BR, at least in the region corresponding to the crotch portion of the first core, the BR in three directions: the vertical direction, the horizontal direction, and an oblique direction that intersects both the vertical direction and the horizontal direction, The absorbent body according to any one of <1> to <19> above, each having a particle diameter of 5.0/mm or less.
BR=(B _w /B _d )/T0 _c (1)
B _w : Bending rigidity of the laminated structure after liquid absorption B _d : Bending rigidity of the laminated structure before liquid absorption T0 _c : Amount of change in thickness of the laminated structure before and after liquid absorption calculated by the following formula (2) T0 _c = T0 _w - T0 _d (2)
T0 _w : Thickness of the laminated structure after liquid absorption under 4.9 mN/cm ² loads T0 _d : Thickness of the laminated structure before liquid absorption under 4.9 mN/cm ² loads <21>
The BR in each of the three directions of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet is preferably 4.8/mm or less, more preferably 4.5. /mm or less, the absorbent body according to <20> above.
<22>
The BR in each of the three directions of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet is preferably 0.1/mm or more, more preferably 0.3. /mm or more, the absorbent body according to <20> or <21> above.
<23>
The flexural rigidity Bw of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet in the vertical direction, the horizontal direction, or the diagonal direction after liquid absorption _is preferably The absorber according to any one of <20> to <22> above, which has an electrical resistance of 200 mN·cm ² /cm or less, more preferably 100 mN·cm ² /cm or less.
<24>
The flexural rigidity Bw of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet in the vertical direction, the horizontal direction, or the diagonal direction after liquid absorption _is preferably The absorber according to any one of <20> to <23>, which has an electrical resistance of 0.3 mN·cm ² /cm or more, more preferably 0.5 mN·cm ² /cm or more.
<25>
The bending rigidity B _d of the laminated structure (first core side laminated structure) including the first sheet, the first core, and the intermediate sheet in the vertical direction, the horizontal direction, or the diagonal direction before liquid absorption is preferably The absorber according to any one of <20> to <24> above, which has an electrical resistance of 19.6 mN·cm ² /cm or less, more preferably 15 mN·cm ² /cm or less.
<26>
The bending rigidity B _d of the laminated structure (first core side laminated structure) including the first sheet, the first core, and the intermediate sheet in the vertical direction, the horizontal direction, or the diagonal direction before liquid absorption is preferably The absorber according to any one of <20> to <25>, which has an electrical resistance of 0.1 mN·cm ² /cm or more, more preferably 0.2 mN·cm ² /cm or more.
<27>
Thickness of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet under a load of 4.9 mN/cm ² (=0.5 gf/cm ² ) after liquid absorption The absorbent body according to any one of <20> to <26>, wherein (maximum thickness) T0 _w is preferably 1 mm or more, more preferably 2 mm or more.
<28>
Thickness of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet under a load of 4.9 mN/cm ² (=0.5 gf/cm ² ) after liquid absorption The absorbent body according to any one of <20> to <27>, wherein (maximum thickness) T0 _w is preferably 30 mm or less, more preferably 15 mm or less.
<29>
Thickness of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet under a load of 4.9 mN/cm ² (=0.5 gf/cm ² ) before liquid absorption The absorbent body according to any one of <20> to <28>, wherein (maximum thickness) T0 _d is preferably 0.1 mm or more, more preferably 0.3 mm or more.
<30>
Thickness of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet under a load of 4.9 mN/cm ² (=0.5 gf/cm ² ) before liquid absorption The absorbent body according to any one of <20> to <29>, wherein (maximum thickness) T0 _d is preferably 5 mm or less, more preferably 3 mm or less.
<31>
The absorbent body according to any one of <20> to <30>, wherein the ratio of the B _w in two directions arbitrarily selected from the three directions is 0.8 or more and 1.2 or less, respectively. .

<32>
In the liquid absorbing state of the absorbent body, the compressive deformation rate of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet is the same as that of the second sheet, the second core, and the intermediate sheet. The absorbent body according to any one of <1> to <31>, which has a higher compressive deformation rate than the laminate structure (second core side laminate structure) made of the intermediate sheet.
<33>
In the liquid absorption state of the absorber, the compressive deformation rate of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet, the second sheet, the second core, and The ratio of the compressive deformation rate of the laminated structure made of the intermediate sheet (second core side laminated structure) is preferably 2.0 or more, more preferably 2.3 or more as the former/latter, assuming that the former > the latter. The absorber according to <32> above.
<34>
In the liquid absorption state of the absorber, the compressive deformation rate of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet, the second sheet, the second core, and The ratio of the compressive deformation rate of the laminated structure made of the intermediate sheet (second core side laminated structure) is preferably 10.0 or less, more preferably 5.0 or less as former/latter, assuming that the former > the latter. The absorbent body according to <32> or <33> above.
<35>
In the liquid absorption state of the absorber, the compressive deformation rate of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet is the same as that of the second sheet, the second core, and the intermediate sheet. <32> to <34 above, which is preferably 40% or more, more preferably 45% or more, assuming that the compressive deformation rate is larger than the compressive deformation rate of the laminated structure (second core side laminated structure) consisting of the intermediate sheet. ＞The absorber according to any one of ＞.
<36>
In the liquid absorption state of the absorber, the compressive deformation rate of the laminated structure (first core side laminated structure) consisting of the first sheet, the first core, and the intermediate sheet is the same as that of the second sheet, the second core, and the intermediate sheet. <32> to <35 above, which is preferably 80% or less, more preferably 75% or less, assuming that the compressive deformation rate is larger than the compressive deformation rate of the laminated structure (second core side laminated structure) consisting of the intermediate sheet. ＞The absorber according to any one of ＞.
<37>
In the liquid absorbing state of the absorbent body, the compressive deformation rate of the laminated structure (second core side laminated structure) consisting of the second sheet, the second core, and the intermediate sheet is the same as that of the first sheet, the first core, and the intermediate sheet. <32> to <36 above, which is preferably 10% or more, more preferably 15% or more, assuming that the compressive deformation rate is smaller than the compressive deformation rate of the laminated structure (first core side laminated structure) consisting of the intermediate sheet. ＞The absorber according to any one of ＞.
<38>
In the liquid absorbing state of the absorbent body, the compressive deformation rate of the laminated structure (second core side laminated structure) consisting of the second sheet, the second core, and the intermediate sheet is the same as that of the first sheet, the first core, and the intermediate sheet. <32> to <37 above, which is preferably 60% or less, more preferably 55% or less, assuming that the compressive deformation rate is smaller than the compressive deformation rate of the laminate structure (first core side laminate structure) consisting of the intermediate sheet. ＞The absorber according to any one of ＞.

<39>
Adhesives (24, 25) are applied to the skin-facing surface and the non-skin-facing surface of the second core, and the adhesive (24) on the non-skin-facing surface of the second core is stronger than the adhesive (24) on the non-skin-facing surface of the second core. The absorbent body according to any one of <1> to <38>, wherein the amount of application per unit area is larger than that of the adhesive (25) on the skin-facing surface of the two cores.
<40>
On the premise that the ratio of the basis weight of the adhesive (24) on the non-skin facing surface side of the second core and the basis weight of the adhesive (25) on the skin facing surface side of the second core is the former > the latter, The absorber according to <39> above, wherein the former/latter ratio is preferably 1.1 or more, more preferably 1.3 or more.
<41>
On the premise that the ratio of the basis weight of the adhesive (24) on the non-skin facing surface side of the second core and the basis weight of the adhesive (25) on the skin facing surface side of the second core is the former > the latter, The absorber according to <39> or <40>, wherein the former/latter ratio is preferably 15 or less, more preferably 10 or less. <42>
The basis weight of the adhesive (24) on the non-skin facing surface of the second core is preferably 3.0 g/m ² or more, more preferably 4.5 g/m ² or more, <39> to <41>.
<43>
Any of <39> to <42> above, wherein the basis weight of the adhesive (24) on the non-skin facing surface of the second core is preferably 40 g/m ² or less, more preferably 20 g/m ² or less. The absorbent body according to item 1.
<44>
<39> to <43>, wherein the basis weight of the adhesive (25) on the skin-facing side of the second core is preferably 1.3 g/m ² or more, more preferably 1.5 g/m ² or more. ＞The absorber according to any one of ＞.
<45>
Any one of <39> to <44> above, wherein the basis weight of the adhesive (25) on the skin-facing surface of the second core is preferably 35 g/m ² or less, more preferably 15 g/m ² or less. The absorbent body according to item 1.

<46>
The above <1> to <45>, wherein the second sheet and the intermediate sheet are joined together, and the intermediate sheet and the first sheet are joined in a region overlapping with the through hole in a plan view. The absorber according to any one of the above.
<47>
The absorbent body according to <46>, wherein the second sheet and the intermediate sheet are joined in preferably 10% or more, more preferably 20% or more of the area that overlaps with the through hole in plan view.
<48>
The method according to <46> or <47>, wherein the intermediate sheet and the first sheet are joined in preferably 10% or more, more preferably 30% or more of the area that overlaps with the through hole in plan view. Absorber.

<49>
The water-absorbing polymer occupancy of the first core, that is, the ratio of the content mass of the water-absorbing polymer to the total mass of the material forming the first core, is preferably 92% by mass or more, more preferably 95% by mass or more. The absorbent body according to any one of <1> to <48>.
<50>
The water-absorbing polymer occupancy of the second core, that is, the ratio of the content mass of the water-absorbing polymer to the total mass of the material forming the second core, is preferably 30% by mass or more, more preferably 40% by mass or more. The absorbent body according to any one of <1> to <49>.
<51>
The water-absorbing polymer occupancy of the second core, that is, the ratio of the content mass of the water-absorbing polymer to the total mass of the material forming the second core, is preferably 90% by mass or less, more preferably 80% by mass or less, The absorbent body according to any one of <1> to <50>.
<52>
The absorbent body according to any one of <1> to <51>, wherein the content of water-absorbing fibers in the second core is preferably 20% by mass or more, more preferably 30% by mass or more.
<53>
The absorbent body according to any one of <1> to <52>, wherein the content of water-absorbing fibers in the second core is preferably 90% by mass or less, more preferably 80% by mass or less.

<54>
<1> to <53> above, wherein the length of the through hole in the vertical direction is preferably 20% or more, more preferably 30% or more of the length of the second core in the vertical direction. The absorber according to any one of the above.
<55>
<1> to <54>, wherein the length of the through hole in the vertical direction is preferably 95% or less, more preferably 85% or less of the length of the second core in the vertical direction. The absorber according to any one of the above.
<56>
The absorbent body according to any one of <1> to <55>, wherein the length (width) of the through hole in the lateral direction is preferably 1 mm or more, more preferably 2 mm or more.
<57>
The absorbent body according to any one of <1> to <56>, wherein the length (width) of the through hole in the lateral direction is preferably 25 mm or less, more preferably 20 mm or less.
<58>
<1> to <<1>, wherein a plurality of the through holes are arranged intermittently in the lateral direction, and the interval between two adjacent through holes in the lateral direction is preferably 10 mm or more, more preferably 15 mm or more. 57>.
<59>
<1> to <<1>, wherein a plurality of the through holes are arranged intermittently in the lateral direction, and the interval between two adjacent through holes in the lateral direction is preferably 80 mm or less, more preferably 60 mm or less. 58>.
<60>
The absorbent body according to any one of <1> to <59>, wherein the first core has a lower basis weight (mass per unit area) of the water-absorbing polymer than the second core.
<61>
The ratio of the basis weight of the water-absorbing polymer of the first core to the basis weight of the water-absorbing polymer of the second core is preferably 1.1 or more, more preferably 1.1 or more as the latter/former, assuming that the former < the latter. The absorbent body according to any one of <1> to <60>, which has a molecular weight of 1.3 or more.
<62>
The ratio of the basis weight of the water-absorbing polymer of the first core to the basis weight of the water-absorbing polymer of the second core is preferably 10 or less, more preferably 5. 0 or less, the absorbent body according to any one of <1> to <61> above.
<63>
The second core extends across the center in the vertical direction in the same direction, and a portion of the second core located on one side in the vertical direction (the longitudinal direction of the absorbent body) is longer than the second core. Any one of the items <1> to <62> above, wherein the second core contains more water-absorbing material (core forming material) than the portion located on the other side in the longitudinal direction (longitudinal direction of the absorbent body). Absorber described in.

<64>
Regarding the Klemm water absorption height measured according to JIS P8141, the size relationship of "the first sheet ≦ the second sheet < the intermediate sheet" is established, and the Klemm water absorption height of the intermediate sheet is 20 mm or more. The absorbent body according to any one of the above items <1> to <63>.
<65>
The absorbent body according to any one of <1> to <64>, wherein the intermediate sheet is paper with a crepe rate of 5% or more, and the second sheet has a crepe rate of less than 1%.
<66>
The absorbent body according to any one of <1> to <65>, wherein the second sheet includes a nonwoven fabric.
<67>
An absorbent article comprising the absorbent body according to any one of <1> to <66>.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

[Examples 1-2 and Comparative Examples 1-2]
A deployable disposable diaper having the same basic structure as the diaper 1 shown in FIG. 1 was produced according to a conventional method. The absorbent body of the produced disposable diaper included a top sheet, an absorbent body, and a back sheet in the order closest to the wearer's skin. As the top sheet, a hydrophilic air-through nonwoven fabric with a basis weight of 25 g/m ² was used. The back sheet is a laminate of a resin film and a nonwoven fabric, in which the skin-facing side is made of a polyethylene resin film with a basis weight of 18 g/m ² and the non-skin-facing side is made of a hydrophobic air-through nonwoven fabric with a basis weight of 25 g/m ² . was used. As the absorbent body, one having the same structure as the absorbent body 10 described above was used. As the first sheet, an SMS nonwoven fabric with a basis weight of 10 g/m ² is used, as the second sheet an SMS nonwoven fabric with a basis weight of 10 g/m ² is used, and as an intermediate sheet, a tissue with a basis weight of 16 g/m ² (this kind of A paper similar to that used as a mount for wrapping an absorbent core in absorbent articles was used.
By appropriately changing the method of dispersing the water-absorbing polymer (spraying amount per unit time, dispersion pattern, etc.) during the production of the first core, three types of first cores with different distribution states of the water-absorbing polymer (Fig. 7) was manufactured. The water-absorbing polymer occupancy of the three types of first cores was all 100%.
As the second core, two types of second cores were used, which were made of a fiber stack containing water-absorbing fibers (softwood bleached kraft pulp; NBKP) and a water-absorbing polymer, and the basis weights of the core forming materials were different from each other. In each second core, the second sheet and the intermediate sheet were joined in a region that overlapped with the through hole in plan view.
Using any one of the three types of first cores and any one of the three types of second cores, a plurality of expandable disposable diapers in which the distribution state of the water-absorbing polymer in the first core is different from each other is produced. , Examples or Comparative Examples.

[Comparative example 3]
A deployable disposable diaper was produced in the same manner as in Example 2, except that an absorbent body having only a second core without having a first core was used.

FIG. 7 shows a schematic configuration of the first core side laminated structure (the laminated structure consisting of the first sheet 11, the first core 14, and the intermediate sheet 13) in Examples 1 and 2 and Comparative Examples 1 and 2. . Note that in FIG. 7, from the viewpoint of easy understanding, one sheet (the first sheet 11 or the intermediate sheet 13) that covers the first core 14 (water-absorbing polymer 20) is omitted.

In the first core-side laminated structure 17A common to Examples 1 and 2, as shown in FIG. The first core 14 is formed between the sheets 11 and 13 by uniformly dispersing the water-absorbing polymer 20 over the entire area with almost no gaps. In the first core-side laminated structure 17A, the basis weight of the water-absorbing polymer 20 in the first core 14 was 110 g/m ² , and the length L1 in the lateral direction Y of the first core 14 was 110 mm.

In the first core-side laminated structure 17B of Comparative Example 1, as shown in FIG. 7(b), the first sheet 11 and the intermediate sheet 13, which are rectangular in plan view and have the same shape and size, are coated over the entire area except for the peripheral edges. A first core 14 is formed between both sheets 11 and 13 by intermittently dispersing the water-absorbing polymer 20 in a predetermined pattern. Specifically, the dispersion pattern of the water-absorbing polymer 20 in the first core-side laminated structure 17B is a so-called honeycomb shape in which regular hexagons are arranged without any gaps in a plan view, and the water-absorbing polymer 20 is arranged along each regular hexagon. has been done. In the first core-side laminated structure 17B, the basis weight of the water-absorbing polymer 20 in the first core 14 was 100 g/m ² , and the length L1 in the lateral direction Y of the first core 14 was 110 mm. Further, the length (the length of one side of the regular hexagon) indicated by the symbol L10 in FIG. 7(b) was 8 mm.

In the first core-side laminated structure 17C of Comparative Example 2, as shown in FIG. 7(c), a pair of water-absorbing polymers 20 extending in the longitudinal direction Spreading regions 20N, 20N are formed. The pair of non-spreading areas 20N, 20N each have a convex shape toward the other non-spreading area 20N in plan view, and the top of the convexity extends in the longitudinal direction (vertical direction X) of the non-spreading area 20N. It is located in the center of. In the first core side laminated structure 17C, the basis weight of the water-absorbing polymer 20 in the first core 14 (excluding the non-dispersed area 20N) is 300 g/m ² , and the length L1 in the lateral direction Y of the first core 14 is 110 mm. Ta. In addition, the lengths indicated by symbols L2 to L6 in FIG. 7(c) are 200 mm for L2 (the length in the vertical direction X of the non-sprayed area 20N) and 10 mm for L3 (the length in the width direction of the non-sprayed area 20N). , L4 (the shortest distance between the pair of non-spread areas 20N, 20N) is 20 mm, and L5 (the horizontal direction Y between the side edge of the first core 14 along the longitudinal direction X and the non-spread area 20N adjacent to the side edge) L6 (maximum separation distance between a pair of non-sprayed regions 20N, 20N) was 35 mm, and 50 mm.

Regarding the absorbent bodies in the disposable diapers of Examples and Comparative Examples, the first core-side laminated structure (laminated structure consisting of the first sheet, the first core, and the intermediate sheet) and the second core in the liquid-absorbing state of the absorbent body were obtained by the method described above. The compressive deformation rate, the depths C1D and C2D of the recesses C1 and C2, and the thicknesses T1 and T2 of each side laminated structure (a laminated structure consisting of a second sheet, a second core, and an intermediate sheet) were measured.
In addition, for the absorbers in the disposable diapers of Examples and Comparative Examples, the bending rigidity B _d of the first core side laminated structure before liquid absorption in the longitudinal direction X, the lateral direction Y, and the diagonal direction D, and liquid absorption The subsequent bending stiffness B _w and the amount of change in thickness T0 _c (=T0 _w − T0 _d ) before and after liquid absorption were measured, and BR was calculated from the above formula (1).
In addition, regarding the absorbent bodies in the disposable diapers of Examples and Comparative Examples, visibility of irregularities after liquid absorption and flexibility after liquid absorption were evaluated by the following method.
In addition, the liquid absorbency of the absorbers in the disposable diapers of Examples and Comparative Examples was evaluated by the following method.
The above results are shown in Tables 1 and 2 below.

<Measurement method of bending rigidity>
It is generally known that the bending stiffness of an object such as an absorbent body can be expressed as a value measured by KES (Kawabata Evaluation System) manufactured by Kato Tech Co., Ltd. (References: Norio Kawabata, "Standardization and Analysis of Texture Evaluation," 2nd edition, Japan Textile Machinery Society Textile Measurement and Standardization Research Committee, published July 10, 1980). Specifically, we used KES-FB2-AUTO-A (pure bending tester) and KES-FB2-AUTO-L (large-scale bending tester) manufactured by Kato Tech Co., Ltd. to test the absorption of the laminated structure on the first core side. The bending rigidity B _d before liquid absorption and the bending rigidity B _w after liquid absorption can be measured. The measurement procedure is as follows.

(Measurement method of bending rigidity B _d before liquid absorption)
As a measuring device, KES-FB2-AUTO-A (pure bending tester) manufactured by Kato Tech Co., Ltd. is used. A sample prepared according to the following <Sample Preparation Method> is mounted on a test stand of a measuring device, and held in a chuck with an interval of 1 cm. The sample is subjected to pure bending with constant velocity curvature in the range of curvature K=-2.5 to +2.5 cm ^-1 . One cycle of deformation is performed at a deformation speed of 0.50 cm ⁻¹ /sec. The bending rigidity B _d before liquid absorption is calculated from the average value of the slope of the bending moment between curvatures of 0.5 and 1.5 and between -0.5 and -1.5. The bending rigidity B _d before liquid absorption is measured in each of the longitudinal direction X, the lateral direction Y, and the diagonal direction D.

(Method for measuring bending rigidity _Bw after liquid absorption)
As a measuring device, KES-FB2-AUTO-L (large-scale bending tester) manufactured by Kato Tech Co., Ltd. is used. After soaking the sample prepared according to the following <Sample Preparation Method> in physiological saline for 30 minutes, use a water-absorbing sheet such as a Kim towel to wipe off moisture to the extent that no moisture leaks from the sample, and use it as a sample after liquid absorption. . After absorbing the liquid, the sample is attached to the test stand of the measuring device and held in a chuck with a spacing of 4 cm. After absorbing the liquid, the sample is subjected to constant curvature bending within the range of curvature K = -0.4 to +0.4 cm ^-1 . One cycle of deformation is performed at a deformation speed of 0.50 cm ⁻¹ /sec. The bending rigidity _Bw after liquid absorption is calculated from the average value of the slope of the bending moment between curvatures of 0.1 and 0.3 and between -0.1 and -0.3. The bending rigidity _Bw after liquid absorption is measured in each of the vertical direction X, the horizontal direction Y, and the diagonal direction D.

<Method for measuring thickness change T0 _c before and after liquid absorption>
As a measuring device, a KES-G5 handy compression tester manufactured by Kato Tech Co., Ltd. is used. The sample was attached to the test stand of the measuring device, and a load of 4.9 mN/cm ² (=0.5 gf/cm ² ) was applied to the sample by compressing it between plywood boards with a circular plane with an area of 2 cm ² . In this state, measure the thickness of the sample. The compression speed is 0.5 mm/sec, and the maximum compression load is 50 g/cm ² .
When measuring the thickness T0 _d of the first core side laminated structure before liquid absorption under a load of 4.9 mN/ ^cm2 , use the sample (dry sample) prepared by the following <Sample Preparation Method> as the sample. use.
When measuring the thickness T0 _w of the first core side laminated structure after liquid absorption under a load of 4.9 mN/ ^cm2 , the sample (dry sample) prepared by the following <Sample Preparation Method> was soaked in physiological saline. After immersing the sample in water for 30 minutes, use a water-absorbing sheet such as a Kim towel to wipe off the water to an extent that no water leaks from the sample (sample after liquid absorption) and use it as a sample.
By subtracting the thickness T0 _d before liquid absorption from the thickness T0 _w after liquid absorption (T0 _w - T0 _d ), the amount of change in thickness T0 _c before and after liquid absorption is calculated.

<Sample preparation method>
The object to be measured (first core-side laminated structure: laminated structure consisting of a first sheet, a first core, and an intermediate sheet) is taken out from the absorbent article. At this time, if the object to be measured is joined to another member by an adhesive, the adhesive force is removed by blowing cold air from a cold spray on the joined portion before taking it out. This procedure is common to all measurements herein.
Prepare a sample from the measurement target using the following procedure. The sample preparation procedure is shown in FIGS. 8 and 9. FIG. 8 shows the procedure for preparing samples SX and SY for measuring the bending stiffness B _{d and} B _w in the longitudinal direction X or the lateral direction Y, _{and FIG} . This is the procedure for preparing sample SD.
When preparing the sample SX for measuring the bending stiffness in the longitudinal direction X and the sample SY for measuring the bending stiffness in the transverse direction Y, referring to FIG. From the laminated structure consisting of the first core 14 and the intermediate sheet 13, a square shape in a plan view having lengths of 10 cm in the longitudinal direction A separately produced protective sheet P is pasted on each of the four sides to obtain samples SX and SY (see FIG. 8(b)). The protective sheet P has a pair of adhesive members P2, P2 attached to both edges along the longitudinal direction of one side of a base sheet P1 having a rectangular shape (11 cm x 3 cm) in plan view (Fig. 8(c) )reference). Each adhesive member P2 is made of an adhesive such as a hot melt adhesive and has a rectangular shape (11 cm x 0.5 cm) in plan view. One of the pair of adhesive members P2, P2 is used to attach the section S, and the other adhesive member P2 is extended outward from the section S together with the base sheet P1. , is used to fix samples SX and SY to the measuring device (test stand) during bending rigidity measurement. Samples SX and SY each have a square shape in plan view, and the length of one side is 11 cm. The line indicated by the symbol BL in FIG. 8 is the bending line of the sample at the time of bending rigidity measurement.
When preparing a sample SD for bending stiffness measurement in the diagonal direction D, with reference to FIG. Cut out a rectangular shape in plan view with a length of 7 cm in a certain direction, that is, the diagonal direction D, and a length of 11 cm in the direction orthogonal to the diagonal direction D, and attach a protective sheet P to each of the four sides of the cut section S in the same manner as above. to obtain sample SD. Note that the short side of the section S may be the side along the diagonal direction D, and the length of the short side can be changed as appropriate depending on the size of the first core side laminated structure 17, etc., and is 7 cm. It is not necessary, and may be 3 cm, for example.

The material and basis weight of the base sheet P1 can be arbitrarily set within a range that does not affect the measurement of bending rigidity, and examples of the material include nonwoven fabric, resin film, etc., and the basis weight: It is about 5 to 20 g/ ^m2 . A specific example of the base sheet P1 is a spunbond nonwoven fabric having a basis weight of 17 g/m ² .
The basis weight and application pattern of the adhesive in the adhesive member P2 should be such that it does not affect the measurement of bending rigidity and that the protective sheet P does not fall off after absorbing the samples SX, SY, and SD (the water-absorbing polymer in the section S It can be set arbitrarily within the range (no leakage). A specific example of the adhesive member P2 is one in which a hot melt adhesive is applied using a slot spray method so that the solid basis weight is 6 g/m ² .

<Evaluation method of unevenness visibility after liquid absorption>
Take out the absorbent body (a laminate of a top sheet, an absorbent body, and a back sheet) from the absorbent article (disposable diaper) to be evaluated, and add physiological saline to the center of the skin-facing surface (top sheet side) of the absorbent body. After injecting 200 g of water over 1 minute, it was allowed to stand for 30 minutes, and then the absorbent body was folded in half in the vertical direction (longitudinal direction) with the skin-facing surface facing the inner surface. Ten expert panelists were asked to visually inspect the bifold absorbent body from the outside side (non-skin facing side) and rate the difficulty of seeing the unevenness on a scale of 10 to 10. The average value of the evaluation scores of 10 people was taken as the evaluation score for the visibility of unevenness after liquid absorption of the evaluation target. The higher the evaluation score, the more difficult it is to visually recognize the unevenness in the liquid absorption state, and the higher the evaluation.

<Evaluation method of flexibility after liquid absorption>
Take out the absorbent body (a laminate of a top sheet, an absorbent body, and a back sheet) from the absorbent article (disposable diaper) to be evaluated, and add physiological saline to the center of the skin-facing surface (top sheet side) of the absorbent body. After 160 g of water was injected over 1 minute, it was allowed to stand for 30 minutes, and then the absorbent body was folded in half in the vertical direction (longitudinal direction) with the skin-facing surface facing inside. Ten expert panelists were asked to freely touch the folded absorbent body with their hands and fingers, mainly at the folded part and its vicinity, and were asked to rate the softness of the absorbent body on a scale of 10 to 10. The average value of the evaluation scores of 10 people was taken as the evaluation score of the flexibility after liquid absorption of the evaluation target. The higher the evaluation score, the more excellent the flexibility in the liquid absorption state, and the higher the evaluation.

<Evaluation method of liquid absorption>
The absorbent body was taken out from the absorbent article (disposable diaper) to be evaluated, and placed on an inclined surface with an inclination angle of 30°, with the second core side of the absorbent body facing upward. At that time, the longitudinal direction (longitudinal direction) of the absorbent body was aligned with the direction of inclination of the slope, and the front side (ventral side) of the absorbent body was arranged on the lower side of the direction of inclination. After repeatedly injecting physiological saline 5 times at 5 minute intervals (total injection amount 200 g) into the center of the upper surface of the absorber placed on the slope, the weight of the absorber was The amount of liquid absorbed (g) was calculated by subtracting the weight of the absorber before physiological saline injection from the weight after liquid absorption, and evaluated according to the following evaluation criteria.
(Liquid absorbency evaluation criteria)
A (good): The amount of liquid absorbed after 5 injections is 160 g or more B (slightly bad): The amount of liquid absorbed after 5 injections is 100 g or more and less than 160 g C (bad): The amount of liquid absorbed after 5 injections But less than 100g

As shown in Tables 1 and 2, in each example, 1) 90% by mass or more of the material forming the first core is a water-absorbing polymer, and 2) BR≦ in all the vertical, horizontal, and diagonal directions. 5.0/mm, the water-absorbing polymer is uniformly distributed at least in the region corresponding to the crotch of the first core, and 3) the ratio of depth C1D to depth C2D is 40. % or less, it was highly evaluated compared to Comparative Examples 1 and 2, which did not satisfy 2) and 3) above.
In addition, from a comparison between Example 2 and Comparative Example 3, it was found that after liquid absorption, no unevenness was generated on the outer surface of the absorbent article that would suggest breakage of the absorbent body, flexibility after liquid absorption was ensured, and liquid absorption was achieved. It can be seen that it is effective to adopt a laminated structure of a first core and a second core as an absorber in order to improve the properties.

1 Disposable diapers (absorbent articles)
2 Absorbent main body 3 Top sheet 4 Back sheet 10 Absorbent core 11 First sheet 12 Second sheet 12E Extension of second sheet 13 Intermediate sheet 14 First core 15 Second core 15M Part without through holes 15N Through holes 20 Water-absorbing polymer 21 to 25 Adhesive 26 Columnar part C1 Recessed part on the skin-facing side of the absorbent body in a liquid-absorbing state C2 Recessed part 5 on the non-skin-facing side of the absorbent body in a liquid-absorbing state Flap part 6 Leak-proof cuff A Ventral side Part B Crotch C Dorsal part X Vertical direction Y Lateral direction

Claims (17)

It has a vertical direction corresponding to the front and back direction of the wearer and a horizontal direction perpendicular to the longitudinal direction, and has a crotch area located in the wearer's crotch area and a crotch area located on the ventral side of the wearer from the crotch area. An absorbent article for use in an absorbent article comprising: a ventral side portion;
an intermediate sheet, a first sheet disposed on the non-skin facing surface side of the intermediate sheet, and a second sheet disposed on the skin facing surface side of the intermediate sheet, the first sheet and the intermediate sheet A first core containing at least a water-absorbing polymer as a water-absorbing material is interposed between the intermediate sheet and the second sheet, and a water-absorbing second core that swells by liquid absorption is interposed between the intermediate sheet and the second sheet. It is located
A through hole passing through the second core in the thickness direction is formed in a region corresponding to the crotch portion of the second core, and in a region overlapping with the through hole in a plan view, the second sheet and the intermediate sheet is closer than a region of the second core that overlaps the through-hole non-formed portion around the through-hole in a plan view,
90% by mass or more of the material forming the first core is a water-absorbing polymer,
In a region corresponding to the crotch portion of the first core, the water-absorbing polymer is uniformly distributed;
The first core has a main surface area larger than that of the second core, and the main surface is a surface having the largest area in the first core or the second core,
In a liquid absorbing state, the absorbent body has recesses on the skin-facing surface side and the non-skin-facing surface side in a region that overlaps with the through-hole in plan view, and the depth of the recesses on the non-skin-facing surface side is equal to or greater than the skin-facing surface. The absorber has a depth of 40% or less of the recess on the opposing surface side. The absorbent body according to claim 1, wherein the depth of the concave portion on the non-skin facing surface side in a region overlapping with the through hole in plan view is less than 3 mm. Based on the skin-facing surface of the second sheet in a region overlapping with the through-hole in plan view, along the thickness direction of the skin-facing surface of the portion of the second sheet corresponding to the non-through-hole portion from the reference. When the separation distance is D1, and the separation distance along the thickness direction from the reference of the non-skin facing surface of the portion of the intermediate sheet corresponding to the non-through-hole formed portion is D2, the separation distance D1 is greater than the non-skin-facing surface of the intermediate sheet. The absorbent body according to claim 1 or 2, wherein the separation distance D2 increases to a greater degree as the absorbent body absorbs liquid. The absorbent body according to claim 3, wherein the separation distance D1 is longer than the separation distance D2 in the liquid absorption state of the absorbent body. Claims 1 to 4, wherein in a liquid absorption state of the absorbent body, a portion of the first core corresponding to the through hole is thicker than a portion of the first core corresponding to the portion where no through hole is formed. The absorber according to any one of the above. If BR is the bending rigidity change rate per thickness change before and after liquid absorption calculated by the following formula (1) of the laminated structure consisting of the first sheet, the first core, and the intermediate sheet, at least the first In the region corresponding to the crotch of one core, the BR in three directions, the vertical direction, the horizontal direction, and the diagonal direction intersecting both the vertical direction and the horizontal direction, is 5.0/mm or less, respectively. The absorbent body according to any one of claims 1 to 5.
BR=(Bw/Bd)/T0c (1)
Bw: Bending rigidity of the laminated structure after liquid absorption Bd: Bending rigidity of the laminated structure before liquid absorption T0c: Amount of change in thickness of the laminated structure before and after liquid absorption calculated by the following formula (2) T0c = T0w - T0d (2)
T0w: Thickness of the laminated structure after liquid absorption under 4.9 mN/cm ² loads T0d: Thickness of the laminated structure before liquid absorption under 4.9 mN/cm ² loads The absorber according to claim 6, wherein the ratio of the Bw in two directions arbitrarily selected from the three directions is 0.8 or more and 1.2 or less, respectively. In the liquid absorbing state of the absorbent body, the compressive deformation rate of the laminated structure consisting of the first sheet, the first core and the intermediate sheet, and the compressive deformation rate of the laminated structure consisting of the second sheet, the second core and the intermediate sheet. The absorbent body according to any one of claims 1 to 7, wherein the ratio of the compression deformation rate to the compression deformation ratio is 2.0 or more as the former/latter, assuming that the former>the latter. An adhesive is applied to the skin-facing surface and the non-skin-facing surface of the second core, and the adhesive on the non-skin-facing surface of the second core is stronger than the adhesive on the skin-facing surface of the second core. The absorbent body according to any one of claims 1 to 8, wherein the amount of application per unit area is larger than that of the adhesive on the side. Any one of claims 1 to 9, wherein the second sheet and the intermediate sheet are joined together, and the intermediate sheet and the first sheet are joined in a region that overlaps with the through hole in a plan view. The absorber according to item 1. Regarding the Klemm water absorption height measured according to JIS P8141, the size relationship of "the first sheet ≦ the second sheet < the intermediate sheet" is established, and the Klemm water absorption height of the intermediate sheet is 20 mm or more. The absorbent body according to any one of claims 1 to 10. The absorbent body according to any one of claims 1 to 11, wherein the intermediate sheet is paper with a crepe rate of 5% or more, and the second sheet has a crepe rate of less than 1%. The absorbent body according to any one of claims 1 to 12, wherein the second sheet includes a nonwoven fabric. The absorbent body according to any one of claims 1 to 13, wherein the second core is arranged in a region surrounded by a periphery of the first core when the absorbent body is viewed from above. The second core contains at least a water-absorbing fiber and a water-absorbing polymer,
The absorbent body according to any one of claims 1 to 14, wherein the first core has a lower basis weight of the water-absorbing polymer than the second core. The ratio of the basis weight of the water-absorbing polymer of the first core to the basis weight of the water-absorbing polymer of the second core is 1.1 or more and 10.0 or less, assuming that the former < the latter, and the ratio of the latter to the former is 1.1 or more and 10.0 or less. , the absorbent body according to claim 15. An absorbent article comprising the absorbent body according to any one of claims 1 to 16 .

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