JP7202167B2 - Absorbent bodies and absorbent articles - Google Patents

Description

TECHNICAL FIELD The present invention relates to an absorbent body that is used directly or indirectly on the skin and is suitable as an absorbent body for absorbent articles.

Absorbent articles such as disposable diapers and sanitary napkins generally have a topsheet that is relatively close to the wearer's skin and a backsheet that is relatively far from the wearer's skin. , and an absorbent body interposed between the two sheets. Typically, the absorber is mainly composed of water-absorbing fibers such as wood pulp, and often contains water-absorbing polymer particles. Regarding the absorbent used in absorbent articles, as described in Patent Document 1, there is a portion sandwiched between the wearer's thighs when the absorbent article is worn (excretion such as the vulva). part) may be formed as a constricted part that is narrower than the parts positioned in front and behind it to reduce discomfort in the inguinal region. Improvement of various properties such as flexibility, cushioning properties, compression recovery properties, and shape retention properties is a major issue for absorbent bodies used in absorbent articles.

As a technique for improving the absorbent, for example, Patent Document 2 discloses an absorbent containing thermoplastic resin fibers and cellulose-based water-absorbing fibers, wherein the thermoplastic resin fibers cover the surface of the absorbent on the surface sheet side. and the backsheet-side surface of the absorbent body. According to the absorbent body described in Patent Document 2, the thermoplastic resin fibers function as a skeleton for holding other components of the absorbent body, such as cellulose-based water-absorbent fibers, so it is said to be soft and resistant to twisting. .

Patent Document 3 describes an absorbent body containing nonwoven fabric pieces that include heat-fusible fibers and are preliminarily bonded to give a three-dimensional structure, and water-absorbent fibers, and the nonwoven fabric pieces absorb Evenly distributed throughout the body. This three-dimensional nonwoven fabric piece is produced by pulverizing the nonwoven fabric into small pieces using a pulverizing means such as a cutter mill method. 3, it has an irregular shape and does not substantially have a portion that can be regarded as a plane. Patent Document 3 describes a preferred form of the absorbent described in the same document, in which pieces of nonwoven fabric are heat-sealed together. According to the absorbent body described in Patent Document 3, since the nonwoven fabric pieces have a three-dimensional structure, voids are formed inside the absorbent body, and the resilience is improved when water is absorbed. As a result, the water absorption performance is improved. It is said that

In Patent Document 4, a member having excellent cushioning properties such as a film having elasticity separate from the absorber and a sheet obtained by applying uneven processing to a fiber aggregate is provided in the upper part, the lower part, or the inside of the absorber. Absorbent articles are described.

JP 2010-131206 A JP 2015-16296 A Japanese Patent Application Laid-Open No. 2002-301105 JP-A-2000-316902

In order to enhance the wearing comfort of the absorbent article, as described in Patent Document 1, the absorbent article is provided with a constricted portion to reduce discomfort in the groin when worn. It is effective to increase the cushioning property of the absorbent body, and for that purpose, the absorbent body described in Patent Document 3 rather than the absorbent body in which the constituent fibers are individually present as described in Patent Document 2 It is more effective to use absorbents containing fibrous masses, such as pieces of nonwoven fabric. In addition, as described in Patent Document 4, it is also effective to use a member having excellent cushioning properties in addition to the absorbent body in order to improve the wearing comfort of the absorbent article. However, even if these conventional techniques are used, if the absorbent body tends to be twisted by an external force such as body pressure applied when the absorbent article is worn, it does not lead to an improvement in the wearing comfort of the absorbent article. In addition, the absorber is required to have a certain level or more of liquid absorbency. may invite. Further, for example, if a member having excellent cushioning properties as described in Patent Document 4 is arranged between the topsheet and the absorbent body, the separation distance between the topsheet and the absorbent body is increased, and the liquid drawing property is lowered. There is a risk of causing a decrease in liquid absorbency. An absorbent body that does not easily become twisted while the absorbent article is worn and has excellent cushioning properties and liquid drawing properties has not yet been provided.

Accordingly, an object of the present invention is to provide an absorbent body which is less likely to be twisted when worn, less discomfort in the groin region, and which can improve wearing comfort, and an absorbent article using the absorbent body.

The present invention is used by directly or indirectly contacting the skin, and the skin-facing surface is arranged at a position relatively close to the user's skin during use, and the skin-facing surface is arranged at a position relatively far from the user's skin. an excretory part-facing region having a non-skin-facing surface, having a vertical direction corresponding to the front-rear direction of the user and a lateral direction orthogonal thereto, and arranged to face the excretory part of the user when in use; a fiber mass including a synthetic fiber, having a front region disposed longitudinally forward of the excretory portion-facing region and a rear region disposed longitudinally rearward of the excretory portion-facing region; An absorbent body containing a core-forming material containing fibers and a water-absorbent polymer, wherein a plurality of the fiber lumps or the fiber lumps and the water-absorbent fibers are entangled with each other, and an absorbent body having a constricted portion having a lateral length shorter than that of the front region and the rear region, wherein the fiber clumps are present at least in the constricted portion.
The present invention also provides an absorbent article comprising the absorbent body of the present invention.

The absorbent body of the present invention has a high cushioning property and excellent liquid drawing property, and when applied to an absorbent article, it is less likely to be twisted when worn, less uncomfortable in the groin region, and can improve wearing comfort.
Moreover, since the absorbent article of the present invention has such a high-quality absorbent body, it is excellent in wearability and leakproofness.

FIG. 1 is a plan view schematically showing a partly broken surface of a sanitary napkin that is an embodiment of the absorbent article of the present invention, facing the skin (surface sheet side). FIG. 2 is a cross-sectional view schematically showing a section taken along line II of FIG. FIG. 3 is a plan view schematically showing the skin-facing surface side of the absorbent body included in the absorbent article shown in FIG. 4(a) is a cross-sectional view schematically showing a section taken along line II-II in FIG. 3, and FIG. 4(b) is a cross-sectional view schematically showing a cross section taken along line III-III in FIG. FIG. 5 is a vertical cross-sectional view schematically showing the IV-IV line cross section of FIG. FIGS. 6(a) and 6(b) are schematic perspective views of fiber masses used in the present invention, respectively. FIG. 7 is an explanatory diagram of a method for producing a fiber mass used in the present invention. FIG. 8 is an explanatory diagram of the method of measuring the crotch compressive load, and FIG. 8(a) is a schematic top view of the measuring equipment used in the measuring method (viewed from the top side of the measurement sample indicated by reference numeral 100). FIG. 8(b) is a schematic side view of the measuring instrument (viewed from one end in the longitudinal direction of the measurement sample indicated by reference numeral 100).

Hereinafter, the absorbent body of the present invention will be described together with the absorbent article of the present invention having the same based on preferred embodiments thereof with reference to the drawings. 1 and 2 show a sanitary napkin 1 which is one embodiment of the absorbent article of the present invention. The napkin 1 includes an absorbent body 4 that absorbs and retains bodily fluids, a liquid-permeable surface sheet 2 that is arranged on the skin-facing side of the absorbent body 4 and can come into contact with the wearer's skin, and a non-absorbent surface of the absorbent body 4. It comprises a liquid impermeable back sheet 3 arranged on the side facing the skin. As shown in FIG. 1, the napkin 1 has a longitudinal direction X corresponding to the wearer's front-back direction and extending from the wearer's abdomen to the dorsal side through the crotch, and a lateral direction Y orthogonal thereto. and, in the vertical direction X, an excretion-part-facing region B including an excretion-part-facing portion (excretion point) that is arranged to face the wearer's excretion-part such as the vulva when worn, and the excretion-part-facing region B that is longer than the excretion-portion-facing region B. It has a front region A arranged on the front side (wearer's ventral side) and a rear region C arranged on the longitudinal direction rear side (wearer's back side) from the excretory part facing region B, It is divided into three.

As used herein, the term “skin-facing surface” refers to the surface of the absorbent article or its constituent members (for example, the absorbent body 4) that faces the wearer's skin when the absorbent article is worn, i.e. The "non-skin facing surface", which is the side close to the skin, is the side of the absorbent article or its constituent members opposite to the skin side when the absorbent article is worn, that is, the side relatively far from the wearer's skin. It is an aspect that can be It should be noted that the term "when worn" as used herein means a state in which the absorbent article is maintained in a normal and appropriate wearing position, that is, in a correct wearing position of the absorbent article.

The napkin 1, as shown in FIG. It has a pair of wing portions 5W, 5W extending to the outside. The absorbent main body 5 is a main part of the napkin 1, and includes the topsheet 2, the backsheet 3, and the absorbent body 4, and has a front region A, an excretion-portion-facing region B, and a rear region C in the longitudinal direction X. It is divided into three.

When the absorbent article has wings, such as the napkin 1, the excretory part-facing region of the absorbent article of the present invention has wings in the longitudinal direction (longitudinal direction, X direction in the figure) of the absorbent article. is a region with Taking the napkin 1 as an example, an imaginary straight line extending in the horizontal direction Y through the roots of the pair of wing portions 5W, 5W on the front side in the longitudinal direction X, and the roots of the pair of wing portions 5W, 5W on the rear side. The area sandwiched between the imaginary straight line extending in the horizontal direction Y through , is the excretory part facing area B. FIG. In addition, in the napkin 1, the pair of wing portions 5W, 5W are formed symmetrically with respect to the longitudinal center line extending in the longitudinal direction X by dividing the napkin 1 in the lateral direction Y. One wing portion 5W , and that of the other wing portion 5W are at the same position in the longitudinal direction X. As shown in FIG.

In addition, the excretory portion facing region in an absorbent article (not shown) having no wing portion corresponds to the region located in the middle when the absorbent article is divided into three equal parts in the longitudinal direction X.

As shown in FIG. 2, the surface sheet 2 covers the entire skin-facing surface of the absorbent body 4 . On the other hand, the backsheet 3 covers the entire non-skin-facing surface of the absorbent body 4, and extends outward in the lateral direction Y from both side edges along the longitudinal direction X of the absorbent body 4, together with side sheets 6 described later. It forms a side flap part. The side flap portion is a portion of the napkin 1 made of a member extending outward in the horizontal direction Y from the absorbent body 4 . The back sheet 3 and the side sheets 6 are joined to each other at the extending portions from both side edges along the longitudinal direction X of the absorbent body 4 by a known joining means such as adhesive, heat sealing, ultrasonic sealing, or the like. Each of the top sheet 2 and the back sheet 3 and the absorbent body 4 may be joined with an adhesive. As the surface sheet 2 and the back sheet 3, various materials conventionally used for absorbent articles such as sanitary napkins can be used without particular limitation. For example, as the surface sheet 2, a nonwoven fabric having a single-layer or multi-layer structure, a perforated film, or the like can be used. As the back sheet 3, a moisture-permeable resin film or the like can be used.

As shown in FIG. 1 , the side flap portions protrude greatly outward in the lateral direction Y in the excretory portion facing region B, so that a pair of side flap portions are provided on both left and right sides along the longitudinal direction X of the absorbent main body 5 . Wing portions 5W, 5W of are extended. The wing portion 5W is folded back to the non-skin facing surface (outer surface) side of the crotch portion of clothing such as shorts. The wing portion 5W has a substantially trapezoidal shape in which the lower base (longer side than the upper base) is positioned on the side portion side of the absorbent main body 5 in plan view as shown in FIG. is formed with a wing adhesive portion (not shown) for fixing the wing portion 5W to clothing such as shorts. The wing adhesive portion is covered with a release sheet (not shown) made of film, nonwoven fabric, paper, or the like before use. In addition, on both sides along the longitudinal direction X of the skin-facing surface of the absorbent main body 5, that is, the surface facing the skin of the topsheet 2, a pair of absorbents are provided so as to overlap the left and right sides along the longitudinal direction X of the absorbent body 4 in plan view. are arranged over substantially the entire length of the absorbent main body 5 in the longitudinal direction X. As shown in FIG. The pair of side sheets 6, 6 are joined to other members such as the topsheet 2 by a known joining means such as an adhesive at joining lines (not shown) extending in the longitudinal direction X, respectively.

As shown in FIG. 1, the absorbent body 4 extends over substantially the entire length of the napkin 1 (absorbent main body 5) in the longitudinal direction X, and extends from the front region A to the rear region C via the excretory part facing region B. there is The absorbent body 4, which is one embodiment of the absorbent body of the present invention, is incorporated into an absorbent article such as a napkin 1, and is indirectly applied to the human skin, that is, through a member such as the topsheet 2. A skin-facing surface (a surface facing the surface sheet 2) that is used by being indirectly applied to the skin and is located relatively close to the skin of the user, that is, the wearer of the napkin 1 during use. , a non-skin-facing surface (surface facing the backsheet 3) arranged at a position relatively far from the user's skin, and further, the vertical direction X corresponding to the user's front-back direction and the vertical direction X perpendicular thereto. and a front region A, an excretory part-facing region B, and a rear region C in the vertical direction X. The front region A of the absorbent body 4 is a portion located in the front region A of the napkin 1 in the absorbent body 4, and the excretory part facing region B of the absorbent body 4 is located in the excretion part facing region B of the napkin 1 in the absorbent body 4. A rear region C of the absorbent body 4 is a portion of the absorbent body 4 located in the rear region C of the napkin 1 . The absorbent body of the present invention can also be used by directly applying it to the skin without using a member such as a sheet, in addition to such a form in which it is applied indirectly to the skin.

The absorber 4 is shown in FIGS. 3-5. The absorbent body 4 in this embodiment comprises a liquid absorbent core 40 containing a core forming material and a liquid permeable core wrap sheet 41 covering the outer surface of the absorbent core 40 . Thus, in this embodiment, the core forming material is integrated by being wrapped with the core wrap sheet 41 . The absorbent core 40 constitutes the main body of the absorbent body 4 and has a shape elongated in the vertical direction X in plan view as shown in FIG. The absorbent core 40 is arranged on the napkin 1 with its longitudinal direction aligned with the longitudinal direction X of the napkin 1 . The absorbent core 40 and the core wrap sheet 41 may be joined with an adhesive such as a hot-melt adhesive.

In this embodiment, the core wrap sheet 41 is a single continuous sheet having a width two to three times the length of the absorbent core 40 in the lateral direction Y, as shown in FIGS. , covering the entire skin-facing surface of the absorbent core 40 and extending outward in the lateral direction Y from both side edges 40S, 40S along the longitudinal direction X of the absorbent core 40. It is rolled down below the absorbent core 40 and covers the entire non-skin facing surface of the absorbent core 40 . In the present invention, the core wrap sheet does not have to be such a single sheet. For example, one skin side core wrap sheet covering the skin facing surface of the absorbent core 40 and the skin side Separately from the core wrap sheet, the non-skin side core wrap sheet covering the non-skin facing surface of the absorbent core 40 may be included. Moreover, the absorbent body of the present invention may not be provided with a core wrap sheet, and the present invention includes an absorbent body comprising only an absorbent core.

The absorbent core 40 can be said to be substantially the absorbent body 4 itself, and unless otherwise specified, the following description of the absorbent core 40 is appropriately applied as the description of the absorbent body of the present invention. The absorbent body of the present invention includes a form composed only of an absorbent core without a core wrap sheet, and in such a form, the absorbent body and the absorbent core have the same meaning.

The absorbent core 40 is mainly composed of a core-forming material, and typically composed of only the core-forming material. The core-forming material includes at least water-absorbing fibers 12F, fiber mass 11 containing fibers 11F, and water-absorbing polymer 13. As shown in FIG. The constituent fibers 11F of the fiber mass 11 are synthetic fibers.

As used herein, the term "fiber mass" refers to a fiber aggregate in which a plurality of fibers are bundled together. The fiber mass used in the present invention may be a fiber aggregate of a fixed shape, such as a sheet piece obtained by cutting a synthetic fiber sheet having a certain size with a cutter or the like, regardless of its manufacturing method, or An irregular-shaped fiber aggregate produced by pulverizing a nonwoven fabric mainly composed of synthetic fibers into small pieces, or by tearing off or tearing off, such as the nonwoven fabric pieces described in Patent Document 2, may also be used. However, in such an amorphous fiber assembly, the constituent fibers are randomly oriented due to the manufacturing method, so the surface is rough with fibers protruding from various places on the surface. Therefore, when an amorphous fiber aggregate is used as a core forming material, the fiber aggregates are entangled with each other with a relatively strong bonding force over their entire surfaces, and as a result, the individual fiber aggregates are free to move. There is a risk that the flexibility and cushioning properties will be reduced due to a significant limitation in the degree of absorption, and there will be a risk that the liquid absorbency will be reduced because it will be difficult to create gaps through which body fluids can pass. In this regard, a fixed-shaped fiber aggregate does not have such disadvantages and is preferably used in the present invention. The fiber clump 11 of this embodiment is a fixed-shaped fiber aggregate as described later.

As described above, the fiber mass 11 is a fiber assembly in which a plurality of fibers 11F are aggregated and integrated, and a plurality of the fiber masses 11 are present in the absorbent core 40 while maintaining their shape. The fiber mass 11 mainly contributes to improvement of the flexibility, cushioning properties, compression recovery properties, and shape retention properties of the absorbent core 40 due to the form of the fiber assembly.

A plurality of water-absorbent fibers 12F are present in the absorbent core 40, and although the plurality of water-absorbent fibers 12F can be entangled with each other, they are not aggregated like the constituent fibers 11F of the fiber mass 11, and exist individually. do. The water absorbent fibers 12F mainly contribute to improving the liquid absorbency of the absorbent core 40 and also contributes to improving the shape retention of the absorbent core 40 .

As the water-absorbing fibers 12F, water-absorbing fibers conventionally used as a material for forming the absorbent body of this type of absorbent article can be used. Examples of water-absorbing fibers include natural fibers such as wood pulp such as softwood pulp and hardwood pulp, non-wood pulp such as cotton pulp and hemp pulp; modified pulp such as cationized pulp and mercerized pulp; cupra, rayon, etc. and the like, and these can be used alone or in combination of two or more. Considering that the main role of the absorbent fibers 12F is to improve the liquid absorbency of the absorbent body 4, natural fibers and regenerated fibers (cellulosic fibers) are preferable as the absorbent fibers 12F.

A plurality of water-absorbing polymers 13 are present in the absorbent core 40 as small pieces of water-absorbing polymer, and mainly contribute to the improvement of the liquid absorbency in the absorbent core 40 . The shape of the pieces of the water-absorbent polymer 13 is not particularly limited, and may be, for example, spherical, massive, bale-shaped, fibrous, or irregular. The average particle size of the water-absorbent polymer 13 is preferably 10 μm or more, more preferably 100 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less. As the water absorbing polymer 13, generally, 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. Specifically, acrylic acid polymers such as Aqualic CA and Aqualic CAW (both manufactured by Nippon Shokubai Co., Ltd.) Partial sodium salts are included.

In the absorbent core 40, the plurality of fiber lumps 11 or the fiber lumps 11 and the absorbent fibers 12F are entangled with each other. In the absorbent core 40 of the present embodiment, a plurality of fiber lumps 11 are entangled with constituent fibers (fibers 11F, 12F) in the absorbent core 40 to form one fiber lump continuum. Further, the plurality of fiber clumps 11 may be entangled with each other, and the fiber clumps 11 and the absorbent fibers 12F may be entangled and bonded. Furthermore, usually, a plurality of water absorbent fibers 12F are also entangled with each other. At least some of the plurality of fiber lumps 11 contained in the absorbent core 40 are entangled with other fiber lumps 11 or water absorbent fibers 12F. In the absorbent core 40, all of the plurality of fiber lumps 11 contained therein may be entangled with each other to form one fiber lump continuum. It is possible that they are mixed in the state of combination.

In the absorbent core 40, in addition to containing the fiber clumps 11 having excellent flexibility, etc., the fiber clumps 11 are connected to each other or the fiber clumps 11 and the water absorbent fibers 12F are entangled with each other. The absorbent core 40 has even better responsiveness to external force, and is excellent in flexibility, cushioning properties, and recovery from compression. The absorbent core 40 deforms flexibly against external forces received from various directions when the napkin 1 is worn (for example, the body pressure of the wearer of the napkin 1), and the napkin 1 can be brought into close contact with the wearer's body with good fit. . Such excellent deformation-recovery characteristics of the absorbent core 40 can be exhibited not only when the absorbent core 40 is compressed but also when twisted. That is, since the absorbent core 40 incorporated in the napkin 1 is sandwiched between the thighs of the wearer when the napkin 1 is worn, it is Movement of the thighs may cause twisting around a virtual axis of rotation extending in the longitudinal direction X. The napkin 1 can be easily deformed and recovered from an external force that promotes twisting from the body, and therefore, it is difficult to twist, and the napkin 1 can be given a high fit to the wearer's body.

In the absorbent core 40, the fiber lumps 11 or the fiber lumps 11 and the water-absorbing fibers 12F are entangled. be done.
Form A: A form in which the fiber clumps 11 and the like are bonded by entanglement of the constituent fibers 11F of the fiber clumps 11 rather than fusion bonding.
Mode B: In the natural state of the absorbent core 40 (the state in which no external force is applied), the fiber clumps 11 and the like are not bonded together, but in the state in which the absorbent core 40 is subjected to an external force, the fiber clumps 11 and the like are bonded together. A configuration in which the constituent fibers 11F can be bound by entanglement with each other. Here, "a state in which an external force is applied to the absorbent core 40" means, for example, that the absorbent core 40 has It is in a state where deformation force is applied.

As described above, in the absorbent core 40, the fiber clumps 11 are connected to other fiber clumps 11 or the water-absorbing fibers 12F by entanglement, ie, "entangling", as in the form A. Like B, it also exists in a state where it can be entangled with other fiber clumps 11 or water absorbent fibers 12F. Such binding by entangling the fibers is one of the important points for more effectively exhibiting the function and effect of the absorbent core 40 described above. In particular, the absorbent core 40 preferably has form A of "entanglement" in terms of shape retention. Bonding by fiber entanglement does not have an adhesive component or fusion, and is made only by entanglement of fibers. The degree of freedom of movement of the fiber 12F) is high, so that its individual elements can move within a range that maintains their integrity as an assembly composed of them. In this way, the absorbent core 40 is deformed when receiving an external force because the plurality of fiber clumps 11 contained therein or the fiber clumps 11 and the absorbent fibers 12F are relatively loosely connected. It has a gentle shape retention that is possible, and has a high level of shape retention, cushioning property, compression recovery property, and the like. The napkin 1 having such a high-quality absorbent core 40 fits tightly to the wearer's body and is comfortable to wear.

It is not necessary that all the binding modes via the fiber clumps 11 in the absorbent core 40 are "entangled", and a part of the absorbent core 40 includes other binding modes other than entangling, such as bonding with an adhesive. may be

However, the absorbent core 40 is excluded from the "fusion through the fiber clumps 11" formed in the absorbent core 40 as a result of being integrated with other members of the absorbent article, such as known leak-proof grooves. In the remaining portion, that is, the unprocessed absorbent core 40 itself, it is desirable that the fiber clumps 11 are bonded together or the fiber clumps 11 and the absorbent fibers 12F are bonded only by "fiber entanglement".

From the viewpoint of more reliably exerting the action and effect of the absorbent core 40 described above, the form A, "the fiber lumps 11 bound by entangling" and the form B, "the fiber lumps 11 in a state where they can be entangled" are used. is preferably half or more, more preferably 70% or more, and more preferably 80% or more of the total number of fiber lumps 11 in the absorbent core 40 .
From a similar point of view, the number of fiber lumps 11 having "entanglement" of form A is 70% or more, particularly 80% or more of the total number of fiber lumps 11 having bonding portions with other fiber lumps 11 or water-absorbent fibers 12F. Preferably.

The absorbent core 40 has a constricted portion 40N having a shorter length (width) in the lateral direction Y than the front region A and the rear region C in the excretory part facing region B, as shown in FIG. The constricted portion 40N is a portion in which all or part of the excretion portion-facing region B of the absorbent core 40 is formed to be narrower than the portions positioned in the longitudinal direction X thereof.

In the present embodiment, the entire excretory part facing region B of the absorbent core 40 is the constricted part 40N. As shown in FIG. 3, the width W1 of the constricted portion 40N in the horizontal direction Y is constant over the entire length of the constricted portion 40N in the longitudinal direction X, and the side edges 40S, 40S of the absorbent core 40 are The constricted portion 40N (excretion portion facing region B) and the portions of the front region A and the rear region C near the constricted portion 40N extend in the vertical direction X, and the boundaries between the constricted portion 40N and the regions A and C extend laterally. It extends in the direction Y. The absorbent core 40 is formed symmetrically with respect to the vertical center line that bisects the absorbent core 40 in the horizontal direction Y, and has a dumbbell shape in plan view as shown in FIG.

The shape of the constricted portion 40N in a plan view is not limited to the illustrated form. For example, the width W1 of the constricted portion 40N may be partially different. The width W1 may be shorter than the portions located in front and behind it (the portions near the regions A and C in the constricted portion 40N). Further, the contour line (side edge 40S) of the constricted portion 40N may not be composed only of straight lines extending in the vertical direction X as shown in FIG. A curve that forms Alternatively, only a part of the excretory part-facing region B of the absorbent core 40 may be the constricted part 40N.

The region B facing the excretory part of the absorbent core 40 is a portion that is sandwiched between the wearer's thighs when the napkin 1 is worn, and thus is a portion that tends to give the wearer a feeling of discomfort in the groin region. The presence of the constricted portion 40N formed narrower than the front and rear regions A and C in the excretion facing region B effectively reduces the pressure received in the lateral direction Y from both thighs. Therefore, the wearing discomfort of the inguinal region can be reduced. In addition, the excretory part facing region B of the absorbent core 40 is likely to be twisted around an imaginary axis of rotation extending in the longitudinal direction X due to the movement of both thighs during walking of the wearer. As compared with the rear region C, a strong external force is likely to act on the rear region C, and twisting is likely to occur.

The absorbent core 40 is characterized not only by having a constricted portion 40N in the excretory portion-facing region B, but also by the presence of fiber clumps 11 in the constricted portion 40N as shown in FIG. 4(a). . By forming the constricted portion 40N in the region B facing the excretory portion of the absorbent core 40, a certain effect can be seen in improving the wearing feeling and preventing twisting, but the constricted portion 40N is compared to other portions of the absorbent core 40. As the width is narrow, the material for forming the core is small and the strength is weak. is limited. On the other hand, as in the present embodiment, the presence of fiber clumps 11 excellent in compression recovery and the like in the constricted portion 40N of the excretory portion-facing region B of the absorbent core 40 improves the shape retention of the constricted portion 40N itself. Since various characteristics such as cushioning properties are improved, the anti-distortion effect is improved in combination with the anti-distortion effect of the formation of the constricted portion 40N, and the effect of reducing discomfort in the groin region can also be improved.

Particularly, in this embodiment, as shown in FIGS. 3 and 4(a), the absorbent body 4 is configured to include an absorbent core 40 and a core wrap sheet 41, and B has a constricted portion 40N, and the core wrap sheet 41 covers the outer surface of the constricted portion 40N and extends outward in the lateral direction Y beyond the constricted portion 40N. In the illustrated embodiment, the core wrap sheet 41 covers not only the constricted portion 40N (excretion portion-facing region B) but also the entire outer surface (skin-facing surface and non-skin-facing surface) of each of the front region A and the rear region C. ing. Then, on both sides of the constricted portion 40N in the lateral direction Y, an absorbent core non-existing portion S is formed in which the absorbent core 40 does not exist and only the core wrap sheet 41 exists as a constituent member of the absorbent body 4. It is The absorbent core 40 does not exist in the absorbent core non-existing part S, but the "absent absorbent core" here includes a form in which the material for forming the absorbent core 40 is completely absent, and a form in which the absorbent core 40 is completely absent. In the latter form, the forming material of the absorbent core 40 that is present in the absorbent core non-existing portion S is usually displaced in the longitudinal direction X It is a very small amount compared to both outside. In addition, in FIG. 4, from the viewpoint of easy understanding, in the absorbent core non-existing part S, it is described so that a space exists between the absorbent core 40 and the core wrap sheet 41. Such a space is not necessarily formed in the real thing. For example, when the absorbent body 4 is incorporated into an absorbent article such as a napkin 1, the core wrap sheet 41 in the absorbent core non-existing portion S (the outer side in the lateral direction Y from the constricted portion 40N in the core wrap sheet 41) 2, is in close contact with the absorbent core 40 due to the presence of other members such as the side sheet 6 in its periphery.

Since the absorbent core non-existing part S is more easily deformed than the areas located before and after it in the longitudinal direction X (the area where the combination of the absorbent core 40 and the core wrap sheet 41 in the absorbent body 4 exists). For example, when the napkin 1 is sandwiched between the wearer's thighs while the napkin 1 is being worn, the absorber 4 receives an external force from the lateral direction Y, and the absorbent core non-existing portion S is moved to the periphery. By deforming more than the portion, the external force interferes, and as a result, unexpected deformation of the constricted portion 40N can be effectively prevented. Therefore, according to the napkin 1 of this embodiment, unexpected deformation, ie twisting, of the absorbent core 40 during wearing is more effectively prevented.

From the viewpoint of ensuring that the effects of the constricted portion 40N of the excretory portion-facing region B of the absorbent core 40 are exhibited more reliably, referring to FIG. The ratio of the length (width W1) of the constricted portion 40N in the lateral direction Y to the length (width W2), that is, W1/W2, is preferably 0.5 or more, more preferably 0.7 or more, and preferably It is less than 1.0, more preferably less than 0.9. If the width W2 is not constant and partially different between the regions A and C, the maximum value of the width W2 is used to obtain the ratio.

When the absorbent core 40 is used as a sanitary napkin, the width W1 of the excretory part-facing region B is preferably 40 mm or more, more preferably 50 mm or more, and preferably 75 mm or less, more preferably 70 mm or less.
When the absorbent core 40 is used as a sanitary napkin, the width W2 of each of the front region A and the rear region C is preferably 60 mm or more, more preferably 65 mm or more, and preferably 100 mm or less, more preferably 90 mm or less. is. The width W2 of the front region A and the rear region C may be the same or different.
The width W1 of the absorbent core 40 shown in FIG. 3 is constant, but if the width W1 is not constant, the minimum value of the width W1 is preferably within the above range.

In the present invention, as described above, the fiber clumps 11 need only be present at least in the constricted portion 40N of the excretory portion-facing region B of the absorbent core 40. On the premise that the fiber clumps 11 are present in the constricted portion 40N, The fiber clumps 11 may be uniformly distributed over the entire absorbent core 40, or may be unevenly distributed.

In this embodiment, as shown in FIG. 4(a), in the excretory part-facing region B of the absorbent core 40, that is, in the constricted part 40N, the fiber clumps 11 are arranged on the non-skin-facing surface side B2 rather than the skin-facing surface side B1. relatively abundant in

The skin-facing surface side B1 of the excretion-part-facing region B of the absorbent core 40 is a portion closer to the skin-facing surface when the excretion-part-facing region B of the absorbent core 40 is bisected in the thickness direction. The surface side B2 is a portion closer to the non-skin facing surface in such a case. The same applies to the skin-facing side and the non-skin-facing side of each of the front region A and the rear region C of the absorbent core 40 .

The uneven distribution of the fiber clumps 11 in the absorbent core 40 in this embodiment is compared with the total content mass of the fiber clumps 11 and the water-absorbing fibers 12F used together as the core-forming material of the absorbent core 40. When defined as the ratio of the content mass of the fiber mass 11 to the total mass content of the fiber mass 11 and the water-absorbing fibers 12F (hereinafter also referred to as "fiber mass occupancy"), the fiber mass occupancy of the absorbent core 40 is At least in the excretory portion-facing region B (constricted portion 40N), the skin-facing surface side B1 is smaller than the non-skin-facing surface side B2.

The fiber clump occupancy rate is obtained by measuring the content of each of the fiber clumps 11 and the water-absorbing fibers 12F present in the predetermined measurement target site of the absorbent core 40 (absorbent body 4) by mass, and It is obtained by dividing the measured content mass of the fiber mass 11 by the total value of the content mass of each of the water-absorbing fibers 12F and the fiber mass 11 and expressing it as a percentage. That is, fiber lump occupation ratio (% by mass)={mass content of fiber lumps 11/(mass content of water-absorbing fibers 12F+mass content of fiber lumps 11)}×100.

Ordinary absorbent cores are mainly composed of water-absorbing fibers, and when body fluid is absorbed in the excretory-facing region, it tends to become stiff compared to the front and rear regions, which do not absorb body fluid or absorb only a small amount of body fluid. This tends to cause twisting. On the other hand, in the absorbent core 40 of the present embodiment, the non-skin-facing surface side B2 of the absorbent core 40 adjacent to the skin-facing surface side B1 in the thickness direction has a fiber mass occupancy rate of Larger than the side B1, therefore, the fiber clumps 11 containing synthetic fibers are unevenly distributed, and the area is excellent in shape retention even in a wet state, and the interface between the skin-facing surface side B1 and the non-skin-facing surface side B2 and its vicinity. As described above, since the fiber lumps 11 and the water-absorbing fibers 12F are entangled, twisting is prevented even when the excretory portion-facing region B of the absorbent core 40 absorbs bodily fluids and becomes wet. . In addition, in the excretory portion facing region B (constricted portion 40N) of the absorbent core 40, as described above with respect to the fiber mass occupancy ratio, the absorbent core 40 is set to "the skin facing side B1<the non-skin facing side B2". 40 is excellent in liquid drawing property, and can rapidly draw in and absorb and retain excreted body fluid.

In addition, in the present embodiment, as shown in FIGS. 4 and 5, in the absorbent core 40, the fiber clumps 11 are more concentrated in the excretory part-facing area B (constricted part 40N) than in the front area A and the rear area C. there are many. That is, in the present embodiment, the fiber clump occupancy of the absorbent core 40 is larger in the excretory part facing area B (constricted part 40N) than in the front area A and the rear area C. As shown in FIG.

In this way, regarding the fiber clump occupancy, the size relationship of "front region A, rear region C<excretion part facing region B (constricted part 40N)" is established, so that the absorbent body 4 is twisted when the napkin 1 is worn. Inconvenience is effectively prevented. In addition, since the fiber clump occupancy rate of the excretion part facing region B of the absorbent core 40 is higher than that of the front and rear regions A and C, the region B tends to have a thicker structure than the peripheral portion. It can fit tightly to the wearer's excretory part. On the other hand, the front region A and the rear region C tend to have a thinner structure than the excretion part-facing region B because the fiber mass occupancy rate is lower than that of the excretion part-facing region B, so that they are familiar with the wearer's clothes such as shorts. easy to follow. In this way, with regard to the absorbent core 40, by adopting a configuration in which "the fiber mass occupancy is larger in the excretory part facing region B than in the front region A and the rear region C", when wearing the napkin 1 The absorber 4 is effectively prevented from twisting, and the comfort of wearing the napkin 1 in the longitudinal direction X can be significantly improved.

From the viewpoint of ensuring the effect of the above-described uneven distribution of the fiber lumps 11, it is preferable to set the fiber lump occupancy rate of each part of the absorbent core 40 as follows.
The fiber clump occupancy rate of the non-skin facing surface side B2 of the excretory part facing area B (constricted part 40N) of the absorbent core 40 is higher than that of the other parts (front area A, rear area C) of the absorbent core 40. On the premise that it is high, it is preferably 50% by mass or more, more preferably 90% by mass or more, and 100% by mass, that is, it may contain no water-absorbent fibers 12F instead of containing the fiber mass 11 at all.
On the premise that the fiber mass occupancy on the skin-facing side B1 of the excretory portion-facing region B (constricted portion 40N) of the absorbent core 40 is lower than that on the non-skin-facing side B2, it is preferably 50% by mass or less. , more preferably 10% by mass or less, and 0% by mass, that is, it may not contain the fiber lumps 11 at all instead of containing the water-absorbing fibers 12F.
The difference between the fiber mass occupancy rate on the non-skin facing side B2 and the fiber mass occupancy rate on the skin facing side B1 of the excretory portion facing region B (constricted portion 40N) of the absorbent core 40 is obtained by subtracting the latter from the former. In addition, it is preferably 50% by mass or more, more preferably 90% by mass or more, and 100% by mass, that is, the non-skin facing side B2 contains only the fiber clumps 11, and the skin facing side B1 contains no fiber clumps 11. It does not have to be contained.
The fiber clump occupation ratios of the front region A and the rear region C of the absorbent core 40 are typically set similarly to those of the skin-facing surface side B1 of the excretory part-facing region B of the absorbent core 40 .

From the viewpoint of ensuring that the effect of the uneven distribution of the fiber masses 11 in the excretion part-facing region B described above is exhibited more reliably, all the absorbent core 40 contains in the excretion part-facing region B (constricted portion 40N). It is preferable that 90% by mass or more, particularly 95% by mass or more of the fiber mass 11 is present.

In the excretory part-facing region B of the absorbent core 40, on each of the skin-facing surface side B1 and the non-skin-facing surface side B2, 1) the fiber mass occupancy may be constant without changing in the thickness direction, or 2). The fiber mass occupation rate may gradually increase from the skin-facing surface side B1 toward the non-skin-facing surface side B2. In the form of 2), in the thickness direction of the absorbent core 40, the fiber clumps 11 do not exist on the skin-facing surface of the absorbent core 40 and in the vicinity thereof, or the fiber mass 11 is the lowest in the excretory part-facing region B of the absorbent core 40. On the non-skin-facing surface of the absorbent core 40 and its vicinity, the fiber masses 11 exist at the highest fiber mass occupancy in the excretory part-facing region B of the absorbent core 40 . The front region A and the rear region C of the absorbent core 40 may also have the form of 1) or 2).

As an advantage peculiar to the above-described form 1), it is easy to design independent functions on the skin-facing side and the non-skin-facing side of the absorbent body (absorbent core). In addition, as an advantage peculiar to the above-described form 2), the mixing ratio of the water-absorbing fibers and the fiber clumps gradually changes in the thickness direction of the absorbent body, so that even when an external force is applied to the absorbent body, the fiber clumps intervene. The entangled state is easily maintained in the thickness direction, and the cushioning property of the absorbent body is easily maintained in good condition during use.

Also, the fiber clump occupancy may gradually increase from the front region A and the rear region C of the absorbent core 40 toward the excretory part facing region B. As shown in FIG. For example, in each of the anterior region A and the posterior region C, the fiber mass occupancy rate gradually increases from the outer side toward the internal bundle in the longitudinal direction X, and the excretory portion-facing region B is in the form of 1) or 2) above. good too.

In the present embodiment, as shown in FIG. 4(a), the excretory portion facing region B (constricted portion 40N) of the absorbent core 40 preferably has a fiber mass occupation ratio of 50% by mass or more, more preferably 90% by mass. % or more (hereinafter also referred to as "fiber mass rich site") 11P and a fiber mass occupancy rate of preferably less than 50% by mass, more preferably 10 mass% or less (hereinafter referred to as "absorbent fiber rich site ) 12P in the thickness direction, more specifically, the entire non-skin facing surface side B2 is the fiber mass rich region 11P, and the entire skin facing surface side B1 is the absorbent fiber rich region 12P. It's becoming Therefore, in the excretory portion facing region B of the absorbent core 40 shown in FIG. At the boundary of , the fiber clump occupancy changes greatly.

The water-absorbing fiber-rich portion 12P is a portion having a water-absorbing fiber occupancy of preferably 50% by mass or more, more preferably 90% by mass or more. The term "water-absorbing fiber occupancy" as used herein refers to the ratio of the content mass of the water-absorbing fibers 12F to the total content mass of the fiber masses 11 and the water-absorbing fibers 12F, and the numerator of the above-described calculation formula for the fiber mass occupancy is It is calculated by replacing the "mass content of the fiber mass 11" with the "mass content of the water-absorbing fibers".

In this embodiment, as shown in FIGS. 4B and 5, the front region A and the rear region C of the absorbent core 40 contain almost no fiber lumps 11, and both regions A and C The fiber clump occupancy of is 0% by mass or close to it, and its entirety is the water-absorbent fiber-rich region 12P.

The fiber mass-rich region 11P is mainly composed of the fiber mass 11 and typically contains substantially no water-absorbent fibers 12F. Therefore, the characteristics of the fiber mass 11 are strongly reflected. It contributes to improving the flexibility, cushioning properties, compression recovery properties, shape retention properties, etc. of the absorbent core 40 . It is preferable that the fiber lumps 11 are uniformly distributed over the entire fiber lump rich portion 11P. On the other hand, the water-absorbent fiber-rich portion 12P is mainly composed of the water-absorbent fibers 12F, and typically does not substantially contain the fiber lumps 11, so the characteristics of the water-absorbent fibers 12F are strongly reflected. and mainly contributes to improving the liquid drawing property of the absorbent core 40 . It is preferable that the water absorbent fibers 12F are uniformly distributed over the entire water absorbent fiber rich portion 12P.

In the present embodiment, regarding the fiber mass occupancy of each part of the absorbent core 40, as described above, the size relationship of "front area A, rear area C<excretion part facing area B" and "excretion part facing area B" On the premise that the size relationship of "skin-facing surface side B1<non-skin-facing surface side B2" is established, the positions of the fiber lump-rich portion 11P and the absorbent fiber-rich portion 12P are not particularly limited. A fiber clump-rich portion 11P may be present on the skin-facing surface side B1 of the excretion portion-facing region B, and a water-absorbing fiber-rich portion 12P may be present on the non-skin-facing surface side B2.

In this embodiment, as described above, both the front region A and the rear region C of the absorbent core 40 are entirely water-absorbent fiber-rich regions 12P, and both regions A and C contain almost no fiber clumps 11. Although not shown, both regions A and C may contain the fiber clumps 11 . In that case, in both regions A and C, the fiber clumps 11 may be uniformly distributed or unevenly distributed, but similar to the excretory part-facing region B in this embodiment, the It is preferable to be unevenly distributed. That is, it is preferable that the fiber clump occupancy rate in each of the regions A and C is smaller on the skin-facing side than on the non-skin-facing side. In other words, as a preferred embodiment of the absorbent core 40, there is a form in which the size relationship of "non-skin-facing surface side>skin-facing surface side" is established for the fiber clump occupancy in the entire absorbent core 40. FIG. In such a preferred form, the distribution of the fiber clumps 11 and the absorbent fibers 12F in both regions A and C can be the same as that in the excretory part facing region B. As shown in FIG. In such a preferable form, the entire skin-facing surface side of the absorbent core 40 is the water-absorbent fiber-rich region 12P, so that it is particularly excellent in liquid drawing property and high in liquid absorption performance.

It is preferable that the water-absorbent fiber-rich portion 12P exists from the skin-facing surface of the absorbent core 40 inward in the thickness direction of the absorbent core 40 over 20 to 80% of the thickness of the absorbent core 40. More preferably it is present between 30 and 70%.
The fiber mass rich region 11P preferably exists from the non-skin facing surface of the absorbent core 40 inward in the thickness direction of the absorbent core 40 over 20 to 80% of the thickness of the absorbent core 40. More preferably it is present between 30 and 70%.
The thickness of each of the absorbent fiber-rich portion 12P and the fiber mass-rich portion 11P is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 5 mm or less, further preferably 4 mm or less.
The thickness of each part of the absorbent core 40 is measured by the following method. The thickness of the entire absorbent core 40 (absorbent body 4), the thickness of the napkin 1, and the like can also be measured according to the following methods.

<Method for measuring thickness>
The absorbent core (absorbent body) is placed on a horizontal surface without any wrinkles or bends, and the site to be measured (for example, the skin facing side or the non-skin facing side of the absorbent core) is measured from the absorbent core. Cut out and use as a measurement sample. Then, the thickness of the measurement sample is measured under a load of 5 cN/cm ² . Specifically, a thickness gauge PEACOCK DIAL UPRIGHT GAUGES R5-C (manufactured by OZAKI MFG.CO.LTD.), for example, is used to measure the thickness. At this time, between the tip of the thickness gauge and the sample to be measured, a circular or square plate (acrylic plate with a thickness of about 5 mm), whose size is adjusted so that the load is 5 cN/cm ² in plan view, is placed. and measure the thickness. The thickness is measured at 10 points, and the average value thereof is calculated to be the thickness.

The thickness of the absorbent core 40 is preferably thinner in the front region A and the rear region C than in the center in the lateral direction Y of the excretory portion facing region B (constricted portion 40N). As a result, when the napkin 1 is worn, the front and rear regions A and C of the absorbent core 40 can easily conform to and follow clothing such as shorts, which can further improve the wearing comfort of the wearer's front body and buttocks. In addition, in the absorbent core 40, at least the center in the lateral direction Y of the excretory part facing region B and its vicinity, that is, the central portion, are thicker than the front and rear regions A and C. As shown in FIG. Therefore, in combination with the fact that the fiber mass occupancy is larger in the excretory part-facing area B than in the front and rear areas A and C, when the napkin 1 is worn, the central part in the lateral direction Y of the excretion part-facing area B in the absorbent core 40 The overlapped portion in a plan view can fit the wearer's excretory part with better adhesion. Such a thickness difference in the longitudinal direction X of the absorbent core 40 is such that, as described above, the fiber clump occupancy rate of the excretory part facing region B of the absorbent core 40 is higher than that of the front region A and the rear region C. can be realized with

The absorbent core 40 typically has a uniform thickness over the entire length (entire width) in the lateral direction Y in the excretory part-facing region B, or the central portion in the lateral direction Y is thicker than both sides thereof. In the form of a thick structure with a large thickness, in any form, the above-mentioned size relationship, that is, "thickness of the center (central portion) in the lateral direction Y of the absorbent core 40 in the excretory part facing region B> front region When the relationship between the thickness of the absorbent core 40 in A and the thickness of the absorbent core 40 in the rear region C is established, the thickness of both sides of the absorbent core 40 in the lateral direction Y in the excretion part facing region B> The relationship between the thickness of the absorbent core 40 in the front region A and the thickness of the absorbent core 40 in the rear region C" is also established.

In the absorbent core 40, the ratio between the thickness of the front region A and the thickness of the center of the excretory part facing region B (constricted part 40N) in the lateral direction Y (or the thickest part of the region B) is such that the former < the latter As a premise, the former/latter is preferably 0.1 or more, more preferably 0.3 or more, and preferably 0.9 or less, more preferably 0.8 or less. The ratio between the thickness of the rear region C and the thickness of the center of the excretory part-facing region B in the lateral direction Y (or the thickest portion of the region B) is preferably set in the same manner as described above.
The thickness of the center in the lateral direction Y of the excretory portion facing region B (constricted portion 40N) of the absorbent core 40 (or the thickest portion of the region B) is preferably 3 mm or more, more preferably 4 mm or more, and preferably 4 mm or more. is 10 mm or less, more preferably 8 mm or less.
The thickness of the front region A and the rear region C of the absorbent core 40 is preferably 1 mm or more, more preferably 2 mm or more, and preferably 8 mm or less, more preferably 6 mm or less.

From the viewpoint of more reliably achieving the effects of the uneven distribution of the fiber masses 11 and the effects of the constricted portion 40N, the area of the non-skin-facing surface of the excretion portion-facing region B (the constricted portion 40N) should be 60% or less of the area of the non-skin facing surface of the core 40, particularly 50% or less, and further preferably 40% or less. The excretory part-facing region B of the absorbent core 40 of the present embodiment is a region having a higher fiber mass occupation rate than the front region A and the rear region C, and particularly the non-skin facing surface side B2 has a high fiber mass occupation rate. Therefore, the region B as a whole is a region that can be said to be a “cushion portion” in which the cushioning property of the fiber mass 11 is strongly reflected. Particularly in the present embodiment, the non-skin-facing surface side B2 is the fiber lump-rich region 11P that is mainly composed of the fiber lumps 11 and hardly contains the water-absorbent fibers 12F. can function effectively as a cushion. That is, the ratio of the area of the non-skin-facing surface of the excretory part-facing region B to the area of the non-skin-facing surface of the absorbent core 40 is the same as the "non-skin-facing surface of the absorbent core 40 (absorbent body 4)." The ratio of the area of the non-skin facing surface of the cushion portion (the portion of the absorbent core 40 where the fiber lumps 11 are unevenly distributed on the non-skin facing surface side of the absorbent core 40) to the area of the absorbent core 40” (hereinafter referred to as “cushion portion Also referred to as "area ratio"). The cushion portion area ratio is 60% or less, that is, the area ratio of the excretion portion facing region B where the fiber mass 11 is unevenly distributed on the non-skin facing surface side B2 is 60% or less, so that the front region A and the rear region C The effect is that the feeling of wearing the front body and the buttocks side of the body can be enhanced. The lower limit of the cushion area ratio is preferably 20% or more, more preferably 25%, and still more preferably 30% or more, from the viewpoint of reliably improving the fit of the excretory portion-facing region B and improving the wearing feeling. be. The cushion area ratio is calculated by the following formula.
Cushion part area ratio (%) = (area of non-skin facing surface of cushion part/area of non-skin facing surface of absorbent core) x 100

As described above, the absorbent core 40 contains the water-absorbent polymer 13, and the location of the water-absorbent polymer 13 in the absorbent core 40 is not particularly limited, and is uniformly distributed throughout the absorbent core 40. Although it may be unevenly distributed in a part of the absorbent core 40, it is preferably present at least in the excretory part facing region B (constricted part 40N) of the absorbent core 40. As shown in FIG. As a result, the liquid absorbency can be further improved in combination with the action effect (especially the effect of improving the liquid drawing property) due to the uneven distribution of the fiber lumps 11 described above. Furthermore, in the excretory part facing region B of the absorbent core 40, it is more effective if the water absorbent polymer 13 is more present on the skin facing surface side B1 than on the non-skin facing surface side B2.

In addition, the non-skin facing side B2 of the excretory portion facing region B (constricted portion 40N) of the absorbent core 40 contains not only the fiber mass 11 but also the absorbent fibers 12F and/or the absorbent polymer 13. is preferred. Such a configuration facilitates the introduction of bodily fluids to the non-skin-facing surface side B2, allows the bodily fluids to be efficiently fixed to the non-skin-facing surface side B2, and further improves the absorbency of the absorbent core 40. can.

In the absorbent core 40, the content mass ratio of the fiber lumps 11 and the water-absorbing fibers 12F is not particularly limited on the premise that the above-described specific range of the fiber lump occupation ratio is satisfied, and the constituent fibers (synthetic fibers) of the fiber lumps 11 ) may be appropriately adjusted according to the types of 11F and water-absorbing fibers 12F. For example, when the constituent fibers 11F of the fiber mass 11 are thermoplastic fibers (non-water-absorbing synthetic fibers) and the water-absorbing fibers 12F are cellulose-based water-absorbing fibers, the predetermined effects of the present invention can be obtained more reliably. From the viewpoint of the above, the content mass ratio of the fiber mass 11 and the water-absorbent fiber 12F is preferably 20/80 to 80/20, more preferably 40, as the former (fiber mass 11) / the latter (water-absorbent fiber 12F). /60 to 60/40.

The content of the fiber lumps 11 in the absorbent core 40 is preferably 20% by mass or more, more preferably 40% by mass or more, and preferably 80% by mass or less with respect to the total mass of the absorbent core 40 in a dry state. , more preferably 60% by mass or less.
The content of the water absorbent fibers 12F in the absorbent core 40 is preferably 20% by mass or more, more preferably 40% by mass or more, and preferably 80% by mass with respect to the total mass of the absorbent core 40 in a dry state. 60% by mass or less, more preferably 60% by mass or less.
The content of the water-absorbent polymer 13 in the absorbent core 40 is preferably 1% by mass or more, more preferably 5% by mass or more, and preferably 80% by mass with respect to the total mass of the absorbent core 40 in a dry state. 50% by mass or less, more preferably 50% by mass or less.
As used herein, the term "dry absorbent core" means an absorbent core before it absorbs bodily fluids.

The basis weight of the fiber mass 11 in the absorbent core 40 is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and preferably 640 g/m ² or less, more preferably 480 g/m ² or less. .
The basis weight of the water absorbent fibers 12F in the absorbent core 40 is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and preferably 640 g/m ² or less, more preferably 480 g/m ² or less. be.
The basis weight of the water absorbent polymer 13 in the absorbent core 40 is preferably 5 g/m ² or more, more preferably 10 g/m ² or more, and preferably 200 g/m ² or less, more preferably 100 g/m ² or less. be.

The absorbent core 40 can be manufactured according to a conventional method using a known fiber stacking device equipped with a rotating drum. The fiber stacking device typically includes a rotating drum having a collecting recess formed on its outer peripheral surface, and a core-forming material (fiber mass 11, water-absorbing fibers 12F, and water-absorbing polymer 13) conveyed to the collecting recess. and a duct having a flow path inside, and while rotating the rotating drum about the rotation axis along the drum circumferential direction, the air flow generated in the flow path by suction from the inside of the rotating drum is ridden on the air flow. The core forming material conveyed by the accumulating recess is stacked in the accumulating recess. The absorbent core 40 is formed in the stacking concave portion by such a stacking process. The above-described specific arrangement of the core forming materials in the absorbent core 40 can be realized by appropriately adjusting the stacking order of the core forming materials on the rotating drum in the manufacturing method using the fiber stacking device. . The basis weight of the absorbent core 40 is preferably 100 g/m ² or more, more preferably 200 g/m ² or more, and preferably 800 g/m ² or less, more preferably 600 g/m ² or less.

The fiber mass 11 will be further described below. FIG. 6 shows two typical outer shapes of the fiber mass 11. FIG. The fiber mass 11A shown in FIG. 6(a) has a rectangular parallelepiped shape rather than a quadrangular prism shape, and the fiber mass 11B shown in FIG. 6(b) has a disk shape. The fiber clumps 11A and 11B are common in that they have two base planes 111 facing each other and a body plane 112 connecting the two base planes 111 . Both the basic surface 111 and the skeletal surface 112 are portions that are recognized as having substantially no unevenness at the level applied when evaluating the degree of unevenness of the surface of this type of fiber-based article.

The rectangular parallelepiped fiber mass 11A shown in FIG. 6(a) has six flat surfaces. Each of the four surfaces is the skeletal surface 112 . The basic plane 111 and the skeletal plane 112 intersect each other, more specifically, perpendicular to each other.
The disk-shaped fiber mass 11B of FIG. 6B has two opposing flat surfaces that are circular in plan view and a curved peripheral surface that connects the two flat surfaces. Each of the surfaces is the basic surface 111 and the peripheral surface is the skeletal surface 112 .
The fiber clumps 11A and 11B are also common in that the skeletal surface 112 has a quadrangular shape, more specifically a rectangular shape in plan view.

Each of the plurality of fiber clumps 11 contained in the absorbent core 40 has two opposing basic surfaces 111 and a skeletal surface 112 connecting the two basic surfaces 111, such as the fiber clumps 11A and 11B shown in FIG. It is different from the irregular-shaped fiber assembly in the prior art described above in that it is a "fixed-shaped fiber assembly". In other words, when any one fiber clump 11 in the absorbent core 40 is seen through (for example, when observed with an electron microscope), the see-through shape of the fiber clump 11 varies depending on the observation angle, and one fiber Where there are multiple perspective shapes per mass 11, each of the plurality of fiber masses 11 in the absorbent core 40 has two opposing basic surfaces 111 and connects both basic surfaces 111 as one of the multiple perspective shapes. It has a specific perspective shape with a skeletal surface 112 that The irregular-shaped fiber assembly in the prior art described above does not substantially have a "surface" such as the basic surface 111 or the skeletal surface 112, that is, a broadened portion, and has different external shapes. It is not fixed form.

In this way, when the plurality of fiber clumps 11 contained in the absorbent core 40 is a "fixed-shaped fiber assembly" defined by the basic surface 111 and the skeletal surface 112, it is an irregular-shaped fiber assembly. Since the uniform dispersion of the fiber lumps 11 in the absorbent core 40 is improved compared to the case of , the expected effect (absorbent body (improvement effects such as flexibility, cushioning properties, compression recovery, etc.) are more stably expressed. In particular, in the case of the rectangular parallelepiped fiber mass 11 as shown in FIG. 6(a), the outer surface is composed of two basic surfaces 111 and four skeletal surfaces 112, that is, six surfaces. It is possible to have a relatively large number of opportunities for contact with the elastic fibers 12F, which increases the entanglement, which can lead to an improvement in shape retention and the like.

In the fiber mass 11 , the total area of the two basic surfaces 111 is preferably larger than the total area of the skeletal surface 112 . That is, in the cuboid fiber mass 11A of FIG. 6(a), the sum of the areas of the two basic planes 111 is larger than the sum of the areas of the four skeletal planes 112. In the disk-shaped fiber mass 11B, the sum of the areas of the two basic surfaces 111 is larger than the area of the skeletal surface 112 forming the peripheral surface of the disk-shaped fiber mass 11B. In each of the fiber lumps 11A and 11B, the basic plane 111 is the plane having the largest area among the plurality of planes of the fiber lumps 11A and 11B.

The fiber clump 11, which is a "fixed-form fiber assembly" defined by the two basic planes 111 and the skeletal plane 112 that intersects the two basic planes 111, is manufactured by a manufacturing method different from the conventional technology. It is a thing. A preferred method for manufacturing the fiber clump 11 includes a step of cutting a raw material fiber sheet 10bs into a regular shape using a cutting means such as a cutter, as shown in FIG. The raw fiber sheet 10bs is a sheet having the same composition as the fiber mass 11 and having a dimension larger than that of the fiber mass 11, preferably a non-woven fabric. The plurality of fiber clumps 11 manufactured through such a process have more uniform shapes and dimensions than irregular fiber aggregates manufactured by conventional techniques. 7A and 7B are diagrams for explaining a method of manufacturing the cuboid fiber mass 11A of FIG. 6A, and the dotted lines in FIG. 7 indicate the cutting lines. The absorptive core 40 contains a plurality of fiber clumps 11 having uniform shape and size, which are obtained by cutting the fiber sheet into a regular shape.

As shown in FIG. 7, the cuboid-shaped fiber clump 11A of FIG. 6(a) has a raw material fiber sheet 10bs in a first direction D1 and a second direction intersecting (more specifically, perpendicular to) the first direction D1. It is manufactured by cutting D2 to a predetermined length. Both directions D1 and D2 are predetermined one directions in the plane direction of the sheet 10bs, and the sheet 10bs is cut along the thickness direction Z perpendicular to the plane direction. In this way, in a plurality of rectangular parallelepiped fiber masses 11A obtained by cutting the raw material fiber sheet 10bs in a so-called diced pattern, the cut surface, that is, the surface that comes into contact with a cutting means such as a cutter when cutting the sheet 10bs is usually , the skeletal surface 112, and the non-cutting surface, that is, the surface that does not come into contact with the cutting means, is the basic surface 111. As shown in FIG. The basic surface 111 is the front and rear surfaces (surfaces perpendicular to the thickness direction Z) of the sheet 10bs, and as described above, is the surface having the largest area among the plurality of surfaces of the fiber mass 11A.

The above description of the fiber mass 11A basically applies to the disk-shaped fiber mass 11B shown in FIG. 6(b). The only substantial difference from the fiber clump 11A is the cutting pattern of the raw fiber sheet 10bs. The sheet 10bs may be cut into a circular shape.

Further, the outer shape of the fiber clump 11 is not limited to that shown in FIG. 6, and both the basic surface 111 and the skeletal surface 112 are flat surfaces that are not curved like the surfaces 111 and 112 in FIG. 6(a). Alternatively, it may be a curved surface like the skeletal surface 112 (peripheral surface of the disk-shaped fiber mass 11B) in FIG. 6(b). Further, the basic surface 111 and the skeletal surface 112 may have the same shape and size. Specifically, for example, the outer shape of the fiber mass 11A may be a cube.

The size of the fiber clump 11 is not particularly limited, and can be appropriately set in consideration of the cushioning properties, liquid permeability, and the like of the absorbent core 40 . The area of the basic plane 111 , which is the plane having the largest area among the plurality of planes of the fiber mass 11 , can serve as an indicator of the size of the fiber mass 11 . The area of the basic surface 111 of the fiber mass 11 is preferably 1 mm ² or more, more preferably 5 mm ² or more, and preferably 100 mm ² or less, more preferably 50 mm ² or less.

As a preferable fiber mass 11, the aspect ratio of the basic surface 111 is 1 or close to 1, that is, the shape of the basic surface 111 is square or similar in plan view. When such a fiber mass 11 is used for the absorbent core 40, the absorbent core 40 tends to be bulky, and the cushioning property and the like can be improved.

The aspect ratio of the basic plane 111 is obtained as the ratio of the lengths of the two sides that define the quadrangular basic plane 111 when the plane view shape of the basic plane 111 is a quadrilateral. If the lengths of the two sides are the same, the aspect ratio of the rectangular basic surface 111 in plan view is 1, and if the lengths of the two sides are different from each other, that is, the shape of the basic surface 111 in plan view is as shown in FIG. ), it is obtained as a ratio (L2/L1) of the length L2 of the long side 111b to the length L1 of the short side 111a. When the shape of the basic surface 111 is not rectangular in plan view, as in the fiber clump 11B shown in FIG. calculated as a ratio of If the lengths of the two axes are the same, the aspect ratio of the non-rectangular basic surface 111 in plan view is 1. When there is a short axis and a relatively long long axis, the ratio of the length of the long axis to the length of the short axis (the length indicated by symbol L2 in FIG. 6(b)) (the latter/former ).

The dimensions and the like of each part of the fiber mass 11 (11A, 11B) can be set as follows, for example. The dimensions of each part of the fiber mass 11 can be measured based on an electron micrograph of the fiber mass 11 or the like.
When the basic surface 111 has a rectangular shape in plan view as shown in FIG. 6A, the length L1 of the short side 111a is preferably 0.1 mm or more, more preferably 0.3 mm or more, and still more preferably 0.5 mm. and preferably 10 mm or less, more preferably 6 mm or less, and even more preferably 5 mm or less.
The length L2 of the long side 111b of the basic surface 111 having a rectangular shape in plan view is preferably 0.3 mm or more, more preferably 1 mm or more, still more preferably 2 mm or more, and preferably 30 mm or less, more preferably 15 mm or less, More preferably, it is 10 mm or less.
6, when the basic surface 111 is the surface having the largest area among the plurality of surfaces of the fiber mass 11, the length L2 of the long side 111b is the maximum span length of the fiber mass 11. (the length of the major axis), and the maximum span length matches the diameter of the circular basic surface 111 in the disk-shaped fiber mass 11B in plan view.
The thickness T of the fiber mass 11, that is, the length T between the two opposing basic surfaces 111 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and preferably 10 mm or less, more preferably 6 mm or less. be.

As described above, the two types of surfaces (the basic surface 111 and the skeletal surface 112) of the fiber mass 11 (11A, 11B) are obtained by cutting the raw fiber sheet 10bs with a cutting means such as a cutter when manufacturing the fiber mass 11. and a non-cut surface (basic surface 111) which is a surface inherent to the sheet 10bs and does not come into contact with the cutting means. And, due to the difference between whether or not it is a cut surface, the skeletal surface 112, which is a cut surface, has more fiber ends per unit area than the basic surface 111, which is a non-cut surface. have The term “fiber ends” as used herein means ends in the longitudinal direction of the constituent fibers 11</b>F of the fiber mass 11 . Normally, fiber ends are also present on the basic surface 111 which is a non-cut surface, but the skeleton surface 112 is formed by cutting the raw fiber sheet 10bs because it is a cut surface formed by cutting. A large number of fiber ends, which are cut ends of the constituent fibers 11F, are present throughout the skeletal surface 112. In other words, the number of fiber ends per unit area is greater than that of the basic surface 111. .

Fiber ends present on each surface (basic surface 111, skeletal surface 112) of the fiber mass 11 are located between the fiber mass 11 and other fiber masses 11 contained in the absorbent core 40 and the absorbent fibers 12F. Useful for forming entanglements. In general, the greater the number of fiber ends per unit area, the better the entanglement, which can lead to the improvement of various properties of the absorbent core 40 such as shape retention. As described above, the number of fiber end portions per unit area on each surface of the fiber clump 11 is not uniform, and the number of such fiber end portions per unit area is such that "skeletal surface 112>basic surface 111". Since the size relationship is established, the entanglement with other fibers (other fiber lumps 11, water-absorbing fibers 12F) through the fiber lumps 11 varies depending on the surface of the fiber lumps 11, and the skeletal surface 112 is the basic surface 111 more confounding than That is, the binding force by entangling with other fibers via the skeletal surface 112 is stronger than that via the basal surface 111, and in one fiber mass 11, the basal surface 111 and the skeletal surface 112 may cause a difference in bonding strength with other fibers. In general, the stronger the binding force, the more restricted the freedom of movement of the bound fibers, and the strength (shape retention) of the absorbent core 40 as a whole improves, but the softness tends to decrease. .

In this way, each of the plurality of fiber clumps 11 contained in the absorbent core 40 exerts two types of bonding strength with respect to other surrounding fibers (other fiber clumps 11, water absorbent fibers 12F). The absorbent core 40 thus has both moderate softness and strength (shape retention). When the absorbent core 40 having such excellent properties is used as an absorbent body of an absorbent article according to a conventional method, it is possible to provide a comfortable wearing feeling to the wearer of the absorbent article. At the same time, the inconvenience of breaking the absorbent core 40 due to an external force such as body pressure of the wearer during wearing is effectively prevented.

In particular, in the fiber clumps 11 (11A, 11B) shown in FIG. 6, the total area of the two basic surfaces 111 is larger than the total area of the skeletal surface 112, as described above. For this reason, the basal plane 111, which has a relatively small number of fiber ends per unit area and is therefore relatively less entangled with other fibers, has the opposite properties to the skeletal plane 112. It means that the total area is larger than Therefore, the fiber clumps 11 (11A, 11B) shown in FIG. ), and even if it is entangled with other fibers in the vicinity, it is easily entangled with a relatively weak bonding force, so it is difficult to form large lumps, and the absorbent core 40 has excellent flexibility. can give sexuality.

The constituent fibers 11F of the fiber mass 11 contain synthetic fibers. The synthetic fibers used as the fibers 11F preferably have lower water absorption (weak water absorption) than the water absorbent fibers 12F, and particularly preferably non-water absorbent synthetic fibers. The constituent fibers 11F of the fiber mass 11 may contain fiber components other than synthetic fibers (for example, natural fibers). Not only when the core 40 is in a dry state, but also when it is in a wet state by absorbing water (bodily fluids such as urine and menstrual blood), the effect (shape retention) due to the presence of the fiber mass 11 described above can be obtained. , flexibility, cushioning properties, compression recovery, resistance to twisting, etc.) are stably achieved. The content of the synthetic fibers as the constituent fibers 11F in the fiber mass 11 is preferably 90% by mass or more with respect to the total mass of the fiber mass 11, and 100% by mass, that is, the fiber mass 11 is formed only from synthetic fibers. Most preferably. In particular, when the synthetic fibers as the constituent fibers 11F are non-water absorbent, the above-described effects due to the existence of the fiber lumps 11 are exhibited more stably.

As used herein, the term "water absorbent" can be easily understood by those skilled in the art, for example, pulp is water absorbent. Similarly, it can be readily appreciated that thermoplastic fibers are weakly absorbent (especially non-absorbent). On the other hand, regarding the degree of water absorbency of fibers, relative differences in water absorbency can be compared and a more preferable range can be defined by the value of moisture content measured by the method described below. The higher the value of such moisture content, the stronger the water absorption of the fiber. The moisture content of the absorbent fibers is preferably 6% or more, more preferably 10% or more. Synthetic fibers, on the other hand, preferably have such a moisture content of less than 6%, more preferably less than 4%. In addition, when the moisture content is less than 6%, the fiber can be determined as a non-absorbent fiber.

<Method for measuring moisture content>
The moisture content was calculated according to the moisture content test method of JIS P8203. That is, after 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, the weight W (g) of the fiber sample before absolutely dry treatment was measured in the room. After that, the fiber sample was completely dried by allowing it to stand for 1 hour in an electric dryer (manufactured by Isuzu Manufacturing Co., Ltd.) at a temperature of 105±2°C. After the absolute dry treatment, in a standard test room at a temperature of 20 ± 2 ° C. and a relative temperature of 65 ± 2%, Si silica gel (for example, (Toyota Kako Co., Ltd.) is placed in a glass desiccator (for example, manufactured by TechJam Co., Ltd.) and allowed to stand until the temperature of the fiber sample reaches 20±2°C. After that, the constant weight W' (g) of the fiber sample is weighed, and the moisture content of the fiber sample is obtained by the following formula. Moisture content (%) = (WW'/W') x 100

Similarly, from the viewpoint that the absorbent core 40 can exhibit excellent effects in shape retention, flexibility, cushioning properties, compression recovery, resistance to twisting, etc. in both dry and wet conditions. , the fiber mass 11 preferably has a three-dimensional structure in which a plurality of thermoplastic fibers are heat-sealed to each other.

In order to obtain the fiber clump 11 in which a plurality of heat-sealed portions are three-dimensionally dispersed, the raw fiber sheet 10bs (see FIG. 7) should be similarly configured. The raw fiber sheet 10bs in which the fused portions are three-dimensionally dispersed can be produced by subjecting a web or nonwoven fabric mainly composed of thermoplastic fibers to heat treatment such as hot air treatment, as described above.

Non-water-absorbing synthetic resins (thermoplastic resins) suitable as materials for the constituent fibers 11F of the fiber mass 11 include, for example, polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; Polyacrylic acid, polymethacrylic acid alkyl ester, polyvinyl chloride, polyvinylidene chloride and the like can be mentioned, and one of these can be used alone or two or more of them can be used in combination. The fiber 11F may be a single fiber made of one type of synthetic resin (thermoplastic resin) or a blend polymer obtained by mixing two or more types of synthetic resins, or may be a composite fiber. The composite fiber referred to here is a synthetic fiber (thermoplastic fiber) obtained by combining two or more types of synthetic resins with different components with a spinneret and simultaneously spinning them, and multiple components are continuous in the length direction of the fiber. It is a structure that is bonded to each other within a single fiber. The form of the composite fiber includes core-sheath type, side-by-side type, etc., and is not particularly limited.

Further, it is preferable that the contact angle with water of the fiber mass 11 is less than 90 degrees, particularly 70 degrees or less, from the viewpoint of further improving the ability to draw in body fluids during initial excretion. Such fibers can be obtained by treating the above-mentioned non-water-absorbent synthetic fibers with a hydrophilizing agent according to a conventional method. Usual surfactants can be used as hydrophilizing agents.

<Method for measuring contact angle>
A fiber is taken out from the measurement object (absorbent core), and the contact angle of water with respect to the fiber is measured. As a measuring device, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. Deionized water is used for contact angle measurements. The amount of liquid ejected from an ink-jet type water droplet ejector (a pulse injector CTC-25 with an ejector hole diameter of 25 μm, manufactured by Cluster Technology) is set to 20 picoliters, and water droplets are dropped just above the fibers. The state of dripping is recorded on a high-speed recording device connected to a camera placed horizontally. From the viewpoint of image analysis later, the recorder is preferably a personal computer with a built-in high-speed capture device. In this measurement, an image is recorded every 17 msec. In the recorded image, the first image of water droplets landing on the fiber is captured by the attached software FAMAS (software version is 2.6.2, analysis method is droplet method, analysis method is θ / 2 method, image processing algorithm is non-reflective, the image processing image mode is frame, the threshold level is 200, and no curvature correction is performed. angle. The fiber taken out from the object to be measured is cut into a fiber length of 1 mm, placed on a sample table of a contact angle meter, and maintained horizontally. Two different contact angles are measured for each fiber. N = 5 contact angles are measured to the first decimal place, and the average value of the measured values at a total of 10 points (rounded to the second decimal place) is defined as the contact angle of the fiber with water. The measurement environment is a room temperature of 22±2° C. and a humidity of 65±2% RH.

In addition, when the absorbent body (absorbent core) to be measured is used as a constituent member of other articles such as absorbent articles, and the absorbent body is taken out and evaluated and measured, the absorbent body is used as an adhesive, If the fiber is fixed to another component by fusion bonding or the like, the adhesive strength of the fixed portion is removed by a method such as blowing cold air from a cold spray to the extent that the contact angle of the fiber is not affected. take out from This procedure is common to all measurements in this specification.

Although the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments and can be modified as appropriate.
For example, the absorbent core 40 may have, in the excretory part-facing region B, a protuberant portion that protrudes toward the wearer's skin side of the napkin 1 from the peripheral portion. The raised portion is typically formed such that at least the central portion in the lateral direction Y of the excretory portion-facing region B of the absorbent core 40 protrudes more toward the wearer's skin than the peripheral portion. , the basis weight of the core forming material is larger than that of the peripheral portion, and the thickness thereof is also large.
The absorbent article of the present invention broadly includes articles used for absorbing bodily fluids (urine, loose stool, menstrual blood, sweat, etc.) discharged from the human body. So-called unfolded disposable diapers with tapes, underpants-type disposable diapers, incontinence pads and the like are included.

The following notes are further disclosed with respect to the above-described embodiments of the present invention.
<1> A skin-facing surface that is used directly or indirectly on the skin and is located relatively close to the user's skin during use, and a non-skin surface that is relatively far away from the user's skin. an excretory part-facing area having a skin-facing surface, having a vertical direction corresponding to the front-rear direction of the user and a lateral direction orthogonal thereto, and arranged to face the excretory part of the user during use; A fiber mass having a front region arranged longitudinally forward of the excretory part facing region and a rear region arranged longitudinally rearward of the excretory part facing region, and containing synthetic fibers; and a water-absorbent polymer, wherein a plurality of the fiber lumps or the fiber lumps and the water-absorbent fibers are entangled with each other, wherein An absorbent body having a constricted portion having a lateral length shorter than that of the front region and the rear region, wherein the fiber mass exists at least in the constricted portion.
<2> The absorbent body according to <1>, wherein the ratio of the lateral length of the constricted portion to the lateral length of each of the front region and the rear region is 0.5 or more and less than 1.
<3> The absorbent body includes an absorbent core containing the core-forming material and a core wrap sheet covering the outer surface of the absorbent core, and the absorbent core is attached to the excretory part-facing region. <1> or <2> above, which has a constricted portion, and the core wrap sheet covers the outer surface of the constricted portion and extends laterally outward from the constricted portion. Absorber.
<4> The ratio of the mass content of the fiber lumps to the total mass content of the fiber lumps and the water-absorbing fibers is higher on the skin-facing surface side than on the non-skin-facing surface side, at least in the excretion part-facing region. The absorbent body according to any one of <1> to <3>, which is small.
<5> In the constricted portion of the absorbent body (absorbent core), the non-skin facing side and the skin of the ratio of the content mass of the fiber mass to the total content mass of the fiber mass and the water-absorbing fiber The absorber according to <4> above, wherein the difference between the opposing surface and the former is 50% by mass or more, preferably 90% by mass or more, when the latter is subtracted from the former.
<6> The above-described <4>, wherein the absorbent body (absorbent core) contains only fiber clumps on the non-skin-facing surface side and does not contain any fiber clumps on the skin-facing surface side in the constricted portion. absorber.
<7> The ratio of the content mass of the fiber mass to the total content mass of the fiber mass and the water-absorbent fiber is greater in the excretion part-facing region than in the front region and the rear region, <1> to The absorbent body according to any one of <6>.
<8> In the constricted portion, the ratio of the mass content of the fiber lumps to the total mass content of the fiber lumps and the water-absorbent fibers is smaller on the skin-facing surface side than on the non-skin-facing surface side, and The absorbent body according to <7> above, wherein 90% by mass or more, preferably 95% by mass or more of all fiber lumps contained in the absorbent body (absorbent core) are present in the constricted portion.
<9> Any one of <1> to <8>, wherein the area of the non-skin-facing surface of the excretory part-facing region is 60% or less of the area of the non-skin-facing surface of the absorbent body. absorber.
<10> The water-absorbent polymer is present at least in the excretion-part-facing region, and is more present on the skin-facing side than on the non-skin-facing side in the excretion-portion-facing region, <1> to <9> The absorbent body according to any one of 9>.
<11> An absorbent article comprising the absorbent body according to any one of <1> to <10>.

<12> The absorbent article comprises a vertically elongated absorbent main body comprising a topsheet arranged on the skin-facing side of the absorbent body and a backsheet arranged on the non-skin-facing side. , the absorbent article according to <11>.
<13> The absorbent article has a pair of wing portions extending outward in the horizontal direction from both longitudinal side portions of the excretion portion-facing region of the absorbent main body. > Absorbent article according to.
<14> The wing portion is a portion that is folded back to the non-skin facing surface side of the crotch portion when fixing the absorbent article to the skin facing surface of the crotch portion of clothing, and the clothing facing surface of the wing portion , the absorbent article according to <13>, further comprising a wing adhesive portion that fixes the wing portion to the crotch portion.
<15> The absorbent body (absorbent core) has, in the excretion part-facing region, a protruding portion that protrudes toward the skin side of the wearer of the absorbent article from the peripheral portion, <11 The absorbent article according to any one of > to <14>.
<16> The absorbent article according to <15>, wherein the raised portion has a core-forming material with a larger basis weight than the peripheral portion.
<17> The absorbent article according to any one of <11> to <16>, wherein the absorbent article is a sanitary napkin.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to such Examples.

[Example 1]
An absorbent body having a planar shape similar to that of the absorbent body 4 (absorbent core 40) shown in FIG. Specifically, the fiber mass 11, the water-absorbing fibers 12F, and the water-absorbing polymer 13 are used as core-forming materials, an absorbent core 40 is obtained by a conventional method using a known fiber stacking device, and the outer surface of the absorbent core 40 is obtained. An absorbent body 4 was manufactured by covering the whole with a core wrap sheet 41 having a basis weight of 16 g/m ² . The fiber clump 11 was manufactured by cutting the raw fiber sheet into a diced shape according to FIG. As the raw fiber sheet of the fiber mass, non-water-absorbent thermoplastic fibers composed of polyethylene resin fibers and polyethylene terephthalate resin fibers (non-water-absorbent fibers, fiber diameter 18 μm) are used as constituent fibers, with a basis weight of 21 g / m ² and a thickness A 0.6 mm air-through nonwoven fabric (a fiber sheet having heat-sealed portions between constituent fibers) was used. Bleached softwood kraft pulp (NBKP) was used as the absorbent fiber 12F. As the water absorbing polymer 13, acrylic acid polymer partial sodium salt was used.

The absorber 4 of Example 1 has a length in the vertical direction of 216 mm. The width W2 of the portion near the constricted portion 40N in each of the region A and the rear region C was 70 mm. The thickness of the absorbent body 4 of Example 1 was 5.7 mm in each of the front region A, the excretory part facing region B, and the rear region C, and the thickness from the front region A to the rear region C was substantially the same. Further, in the absorbent core of Example 1, the entire non-skin-facing surface side of the absorbent core is the fiber lump-rich region 11P, and the entire skin-facing surface side of the absorbent core is the absorbent fiber-rich region 12P. , the longitudinal length of the anterior region A was 46 mm, the longitudinal length of the excretory part facing region B was 80 mm, and the longitudinal length of the posterior region C was 90 mm. In addition, the cushion portion area ratio of the absorber of Example 1 (ratio of the area of the non-skin-facing surface of the excretion portion-facing region B to the total area of the non-skin-facing surface of the absorber) It was 100% because the entire area of the surface was formed of the cushion portion. In Example 1, the basis weight of the fiber mass of the absorbent core 40 was 140 g/m ² , and the basis weight of the water absorbent fibers was 210 g/m ² . In addition, the absorbent core 40 contains 50 g/m ² of the absorbent polymer 13, and 90% by mass or more thereof is contained in the absorbent fiber-rich region 12P. In addition, at the interface between the fiber lump rich portion 11P and the water absorbent fiber rich portion 12P, the fiber lump 11 and the water absorbent fiber 12 are entangled. does not contain the absorbent fibers 12, and the fiber clumps 11 are not contained in the absorbent fiber-rich portion 12P. The value of the "fibrous mass occupation ratio" is a value in a portion other than the interfacial region.

[Example 2]
An absorbent body 4 shown in FIGS. 3 to 5 was manufactured and used as the absorbent body of Example 2. FIG. The dimensions of each region in the longitudinal direction of the absorbent body were the same as those of the absorbent body 4 of Example 1. The thickness of the absorbent body 4 of Example 2 is 3.2 mm in the front region A and the rear region C, and 5.7 mm in the excretion-part-facing region B. It had a protuberant portion protruding toward the skin side. In the absorbent core 40 of Example 2, the entire non-skin-facing surface side B2 of the excretory part-facing region B was the fiber clump-rich region 11P, and the rest of the region was the absorbent fiber-rich region 12P. The cushion area ratio of the absorber of Example 2 was 33%. The absorbent body 4 of Example 2 was the same as the absorbent body 4 of Example 1 except for the above points.

[Reference Example 1]
An absorbent body having the same basic structure as that of Example 1 except that the absorbent core 40 did not contain a fiber mass was manufactured and designated as an absorbent body of Reference Example 1. The absorber of Reference Example 1 had a uniform thickness of 5.7 mm. The basis weight of the absorbent fibers was 350 g/m ² .

[Comparative Example 1]
An absorbent body having the same basic configuration as that of the absorbent body of Example 1 except that the absorbent core does not contain a fiber mass and does not have a constricted portion was produced, and the absorbent body of Comparative Example 1 was manufactured. and The absorber of Comparative Example 1 had a uniform thickness of 5.7 mm. The basis weight of the absorbent fibers was 350 g/m ² .

[Comparative Example 2]
A laminate was produced by laminating a highly elastic cushion sheet on the non-skin-facing side of an absorbent element comprising an absorbent core and a core wrap sheet, and used as an absorbent body of Comparative Example 2. The absorber of Comparative Example 2 had a uniform thickness of 5.7 mm. The absorbent element of Comparative Example 2 had the same basic configuration as the absorbent body of Comparative Example 1, that is, the absorbent core contained no fiber lumps and did not have constricted portions. As the cushion sheet, an air-through nonwoven fabric having a basis weight of 40 g/m ² and having the same shape and size as the absorbent element in plan view is used. and The cushion sheet was fixed so as to cover the entire non-skin facing surface of the absorbent element, and a hot-melt adhesive was used to fix the cushion sheets to each other and to fix the cushion sheet and the absorbent element. In the absorbent body of Comparative Example 2, since the non-skin-facing surface of the absorbent body is entirely formed of the cushion portion, the cushion portion area ratio is 100%. The basis weight of the absorbent fibers was 210 g/m ² .

[Performance evaluation]
Width compressive load, dynamic twist rate, recovery work, and compressive strain rate were measured for the absorbent bodies of each example and comparative example by the following methods. The results are shown in Table 1 below.

In addition, when using an absorbent article as a measurement object, a sanitary napkin having the same basic configuration as the napkin 1 shown in FIG. Used for measurement. An air-through nonwoven fabric having a basis weight of 30 g/m ² was used as the top sheet of the sanitary napkin, and a polyethylene resin film (FL-KDJ100nN, manufactured by Taika Kogyo Co., Ltd.) of 37 g/m ² was used as the back sheet.

<Method for measuring width compression load>
In order to evaluate the contact load exerted on the wearer by the napkins of Examples 1 and 2, Reference Example 1, and Comparative Examples 1 and 2, the width compression load of each napkin was measured. Width compressive load is the lateral (width) compressive load of the absorbent article (sanitary napkin) of the measurement sample, and the lateral external force applied to the absorbent article from the wearer's thigh when wearing the sanitary napkin. corresponds to the contact load exerted on the wearer by the absorbent article when is added. The width compression load is an indicator of the flexibility of the absorbent article or the absorbent body, which is a constituent member thereof, in the lateral direction or width direction. It is highly evaluated as a product that is less likely to be twisted, less uncomfortable in the groin area, and can improve the feeling of wearing.
FIG. 8 shows an overview of the method for measuring the width compressive load. As a measuring instrument, TENSILON RTC-1210S (measuring device K) manufactured by Orientec and jig J were used. The jig J has a pair of arcs J11 and J12 that apply a width compression load to the measurement sample 100 (sanitary napkin), and a pulley J2 that pulls a string J3 attached to one arc J11.
When the sanitary napkin used as the measurement sample 100 has extensions extending laterally outward from the absorbent body, such as wings and rear flaps, the back sheet of the absorbent body of the sanitary napkin is A measurement sample 100 was obtained by attaching a tissue paper to the entire surface of the adhesive portion and folding the extending portion toward the back sheet side. At this time, the width (horizontal length) of the measurement sample 100 was adjusted to be the same as the width (horizontal length) of the core wrap sheet, which is a constituent member of the measurement sample 100 .
As shown in FIG. 8(a), the measurement sample 100 has a vertical (longitudinal) middle portion (excretion portion facing region) at the same horizontal position as the apexes of the pair of arcs J11 and J12 of the jig J, and It was arranged under the fixing string J4 so as to be in contact with the arc J12 on the side of the pulley J2. At this time, the distance between the apexes of the left and right arcs J11 and J12 was adjusted to 100 mm.
At the time of measurement, as shown in FIG. 8(b), the string J3 attached to the arc J11 is pulled by the measuring device K and the pulley J2 to compress the measurement sample 100 to a width of 30 mm. The load when the width of the sample 100 became 50 mm in the compression process was measured as the width compression load of the sample 100 . The measurement conditions were a tensile speed of 50 mm/min and a height of the fixing string J4 from the mounting surface of the measurement sample 100 of 22 mm.

(Measurement result of width compression load)
As shown in Table 1, the width compression load of Example 1 was 166 cN, and the width compression load of Example 2 was 180 cN.
On the other hand, the width compression loads of Comparative Examples 1 and 2 were both 223 cN, and the width compression load of Comparative Example 2 was 307 cN, which were larger than the values of the width compression loads of each example. Moreover, in Comparative Example 3, the measurement was impossible due to buckling.
From this result, the napkins of Examples 1 and 2 have a constricted portion that is narrower than the region before and after the excretory portion facing region, and the fiber clumps are present in the constricted portion, so the width is compressed. It was confirmed that the load can be reduced and the lateral flexibility is high.

<Method for measuring dynamic twist rate>
A sanitary napkin was used as a measurement sample, and the dynamic twist rate of the measurement sample was evaluated using a driven female lower body model. First, the center width of the napkin to be measured (the horizontal length at the center of the napkin in the longitudinal direction) (the center width before walking) was measured, and the napkin was attached to shorts and worn on a female human body model. Next, the human body model is walked at a speed of 100 steps/minute for 30 minutes, and during the walking of the human body model, after walking for 3 minutes, 1.5 g of defiberized horse blood is injected into the attached napkin in 15 seconds. A total of 9 g of defibrinated horse blood was injected into the napkin for 6 repetitions. Then, the napkin was removed from the shorts and the center width (the center width after walking) was measured, and the dynamic twist rate (%) was calculated from the center width before walking and the center width after walking by the following formula. The smaller the numerical value of the dynamic twist rate, the less likely the napkin is twisted, and the higher the evaluation. The defiberized horse blood injected into the measurement object was defiberized horse blood manufactured by Japan Biotest Co., Ltd. and the viscosity at a liquid temperature of 25 ° C. was adjusted to 8 cp. Viscosity measured with a TVB-10M viscometer manufactured by Kisangyo Co., Ltd. with a rotor named L/AdP (rotor code 19) at a rotational speed of 12 rpm.
Dynamic twist rate (%) = [{(central width before walking) - (central width after walking)} / (central width before walking)] x 100

<Measurement method of compression work and recovery work>
The recovery work load (hereinafter also referred to as "WC'") of the measurement object (absorbent body) can generally be expressed as a value measured by KES (Kawabata Evaluation System) manufactured by Kato Tech Co., Ltd. (Reference: Standardization and Analysis of Texture Evaluation (Second Edition), author Toshio Kawabata, published on July 10, 1980). Specifically, WC' can be measured using a compression tester KES-G5 manufactured by Kato Tech Co., Ltd. The measurement procedure is as follows. When measuring WC', it is also possible to measure the work of compression (hereinafter also referred to as "WC").
A 240 mm × 70 mm square sample in plan view (absorbent wrapped with a core wrap sheet) is prepared, and the absorbent is wetted according to the following (method for preparing an absorbent article with a wet absorbent). As a state, let it be a measurement sample. The measurement sample is attached to the test table of the compression test apparatus, and the non-recessed portion of the measurement sample, that is, the portion where the measurement sample remains without being subjected to compression processing, is placed between steel plates having a circular flat surface with an area of 2 cm ² Compress with . In this compression process, the compression speed is 0.2 cm/sec and the maximum compression load is 2450 mN/cm ² . The recovery process is also measured at the same speed. WC is represented by the following formula (1), and WC' is represented by the following formula (2), and the unit is "mN·cm/cm ² ". In the following formula, T _m indicates the thickness under a load of 2450 mN/cm ² , and T _O indicates the thickness under a load of 4.902 mN/cm ² . In addition, P a in the following formula (1) and P _b in the following formula (2 ₎ are the measured load (mN/cm ² ) during the compression process and the measured load (mN/cm ² ) during the recovery process, respectively. indicates

Note that WC' is not displayed on the measurement result screen of KES-G5, and what is displayed on the measurement result screen is WC and the compression recovery rate or compression resilience calculated from WC' (hereinafter referred to as "RC ). In such a case, using the parameters (WC, RC) displayed on the measuring device, WC' is calculated by the following equation.

(Method for preparing absorbent article with wet absorbent)
The absorbent article before injecting the defiberized horse blood is left for 24 hours in an environment with a temperature of 23° C. and a relative humidity of 50% RH to prepare a dry absorbent article. The dry absorbent article is placed horizontally with the surface sheet side (surface facing the skin) facing upward, and an elliptical injection port (long diameter 50 mm, short diameter 23 m) is placed on the surface sheet, 3.0 g of defiberized horse blood was injected from the injection port, allowed to stand for 1 minute, then 3.0 g of defiberized horse blood was further injected, and the state was maintained for 1 minute after injection to obtain a wet absorbent. An absorbent article is obtained. The defiberized horse blood injected into the absorbent article is the same as that prepared in the aforementioned <Method for measuring dynamic twist rate>.

<Method for measuring compression strain rate (ΔT/T ₀ )>
The compressive strain rate (ΔT/T ₀ ) of the sample can be measured using KES described above. Specifically, the compression strain rate (ΔT/T ₀ ) was measured using an automated compression tester KES-G5 manufactured by Kato Tech Co., Ltd. The measurement procedure is as follows.
An “absorbent article (sanitary napkin) having an absorbent body” as a sample is attached to the test table of the compression test device. Next, the sample was compressed between steel plates having a circular plane with an area of 2 cm ² , and the load during compression was gradually increased until the load reached a predetermined maximum value (maximum load). Measure the thickness (compressed thickness) _Tm of the object to be measured. Make sure there are no wrinkles or bends on the object to be measured. The measurement conditions of the compression tester are as follows.
・Compression speed: 0.2mm/sec
・Maximum load: 2450mN/ ^cm2
・SENS: 10
・DEF: 20
The initial thickness (T ₀ ) of the object to be measured was the thickness when the load was 103.9 mN/cm ² . Compressive strain rate (%) is calculated by the following formula.
Compressive strain rate (ΔT/T ₀ ) = {(T ₀ −T _m )/T ₀ )}×100

1 sanitary napkin (absorbent article)
A Front region B Excretion part facing region C Rear region 2 Top sheet 3 Back sheet 4 Absorbent body 40 Absorbent core 40N Constricted part 11 Fiber mass 11F Constituent fiber (synthetic fiber) of fiber mass
111 Basic surface 112 Skeleton surface 12F Water absorbent fiber 11P Fiber lump rich part 12P Water absorbent fiber rich part 13 Water absorbent polymer 41 Core wrap sheet 10bs Raw fiber sheet of fiber lump

Claims (7)

A skin-facing surface that is used in direct or indirect contact with the skin and is located relatively close to the user's skin during use, and a non-skin-facing surface that is located relatively far from the user's skin. and
An excretion part-facing region having a longitudinal direction corresponding to the front-rear direction of the user and a lateral direction perpendicular to the longitudinal direction, the excretion part-facing region being arranged to face the user's excretion part during use, and a longitudinal direction relative to the excretion part-facing region. Having a front region arranged on the front side and a rear region arranged on the rear side in the longitudinal direction from the excretory part facing region,
An absorbent body containing a fiber mass containing synthetic fibers, water-absorbent fibers, and a core-forming material containing a water-absorbing polymer, wherein a plurality of fiber masses or the fiber masses and the water-absorbent fibers are entangled with each other. and
The excretion part-facing region has a constricted portion having a lateral length shorter than that of the front region and the rear region, and the fiber mass is present in at least the constricted portion,
The absorber , wherein the ratio of the mass content of the fiber mass to the total mass content of the fiber mass and the water-absorbing fibers is greater in the excretory part-facing region than in the front region and the rear region . 2. The absorbent body according to claim 1, wherein the ratio of the lateral length of said constricted portion to the lateral length of each of said front region and said rear region is 0.5 or more and less than 1. The absorbent body includes an absorbent core containing the core-forming material and a core wrap sheet covering the outer surface of the absorbent core, and the absorbent core forms the constricted portion in the excretory portion-facing region. 3. The absorbent body according to claim 1, wherein the core wrap sheet covers the outer surface of the constricted portion and extends laterally outward beyond the constricted portion. 2. A ratio of the mass content of the fiber mass to the total mass content of the fiber mass and the water-absorbing fibers is smaller on the skin-facing surface side than on the non-skin-facing surface side, at least in the excretion part-facing region. 4. The absorbent according to any one of 1 to 3. The absorbent body according to any one of claims 1 to 4 , wherein the area of the non-skin facing surface of the excretion part facing region is 60% or less of the area of the non-skin facing surface of the absorbent body. 6. The water-absorbing polymer is present at least in the excretory part-facing region, and is more present on the skin-facing side than on the non-skin - facing side in the excretory part-facing region. Absorber according to. An absorbent article comprising the absorbent body according to any one of claims 1 to 6 .

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