RU2765080C2 - Absorbent element and absorbent product - Google Patents

Abstract

FIELD: absorbent products.

SUBSTANCE: proposed group of inventions relates to an absorbent element for an absorbent product, such as disposable diapers and sanitary pads. The absorbent element includes fibre clusters containing thermoplastic fibres and water-absorbing fibres. The absorbent element includes, in the direction of the plane of the absorbent element, a first zone wherein the multiple fibre clusters are fused with each other, and a second zone wherein the multiple fibre clusters are not fused, but twisted with each other. In at least the second zone, the fibre clusters are twisted with water-absorbent fibres. Fibre clusters include a main part formed by two opposing base surfaces and a frame surface crossing the base surfaces.

EFFECT: production of a high-quality absorbent product with improved absorption properties, exhibiting excellent shape-retaining properties.

33 cl, 9 dwg, 1 tbl, 5 ex

Description

The technical field to which the invention belongs

[0001] The present invention relates to an absorbent element for an absorbent article.

Prerequisites for the creation of the invention

[0002] An absorbent article, such as disposable diapers and sanitary napkins, typically includes a topsheet to be placed relatively close to the user's skin, a backsheet to be positioned relatively away from the wearer's skin, and an absorbent member between these layers. The absorbent body typically includes water-absorbent fibers such as wood pulp as a main component, and in many cases also includes water-absorbent polymer particles. The absorbent used in absorbent articles has serious problems in terms of improving various properties, including flexibility (cushioning properties), compression recovery properties, and shape retention properties.

[0003] For example, as a method for improving absorbent members, Patent Document 1 discloses an absorbent member including thermoplastic resin fibers and water-absorbent cellulose fibers, and the thermoplastic resin fibers are exposed on both the absorbent member surface on the topsheet and the absorbent member surface on the back layer. It is believed that the absorbent according to Patent Document 1 should be soft and not tend to curl because the thermoplastic resin fibers function as a scaffold to hold the water-absorbent cellulose fibers and other components in the absorbent.

[0004] Patent Document 2 discloses an absorbent member that includes pieces of nonwoven fabric including hot-melt fibers and having a three-dimensional structure that has been formed by bonding the fibers together and includes water-absorbent fibers. Pieces of nonwoven fabric having a three-dimensional structure are obtained by cutting the nonwoven fabric into small pieces using cutting means such as a cutting mill type system, and thus have such an indefinite shape as shown in FIG. 1 and FIG. 3 in the Document, due to the production method, and essentially do not have any part considered flat. Patent Document 2 discloses thermally fused nonwoven pieces as a preferred embodiment of an absorbent according to the Document. In the absorbent body according to Patent Document 2, the nonwoven fabric patches have a three-dimensional structure, so that voids are formed in the absorbent body and recovery after water absorption is improved. As a result, water absorption is considered to be improved.

[0005] Patent Document 3 discloses a microfiber material including relatively dense cores of microfibers and fibers or fiber bundles extending outward from the core, and also discloses that a nonwoven fabric including a mixture of microfibers and wood pulp or water-absorbing polymer particles can be used as absorbent element for absorbent articles. This microfiber material is obtained by plucking or tearing a sheet of material such as a non-woven material, thus obtaining an indefinite shape, as with pieces of non-woven material according to Patent Document 2, and it essentially does not have a part that is considered flat.

List of reference documents

Patent Documents

[0006] Patent Document 1: JP 2015-16296 A

Patent Document 2: JP 2002-301105 A

Patent Document 3: JPH01-156560 A

The essence of the invention

[0007] The present invention relates to an absorbent member comprising fiber clusters containing thermoplastic fibers and comprising water absorbent fibers. The absorbent member includes, in the direction of the plane of the absorbent member, a first zone in which a plurality of fiber clusters are fused to each other, and a second zone in which a plurality of fiber clusters are not fused but intertwined with each other. At least in the second zone, the fiber clusters are intertwined with water-absorbing fibers. The fiber cluster includes a main body defined by two opposite base surfaces and a frame surface intersecting with the base surfaces.

The present invention also relates to an absorbent article comprising the absorbent of the present invention.

Brief description of the drawings

[0008] [Fig. 1] FIG. 1(a) is a top view schematically showing one side (skin-facing surface side) of an embodiment of an absorbent member of the present invention; and Fig. 1(b) is a schematic sectional view along line I-I in FIG. 1(a).

[Fig. 2] FIG. 2 is a perspective view schematically showing the second zone in the absorbent member shown in FIG. one.

[Fig. 3] FIG. 3 is a view schematically showing a deformation state of the second zone shown in FIG. 2 during compression.

[Fig. 4] FIG. 4(a) - FIG. 4(e) are views schematically showing the configurations of the first zone in other embodiments of the absorbent member of the present invention according to FIG. 1(a).

[Fig. 5] FIG. 5(a) and FIG. 5(b) are schematic perspective views of the main body in the fiber cluster of the present invention.

[Fig. 6] FIG. 6 illustrates a method for obtaining fiber clusters of the present invention.

[Fig. 7] FIG. 7(a) is an electron microscope image (observation magnification: 25×) of an example of a fiber cluster of the present invention; and Fig. 7(b) schematically shows a fiber cluster in an electron microscope image as a fiber cluster included in the absorbent (second zone) shown in FIG. one.

[Fig. 8] FIG. 8 is a schematic perspective view showing an embodiment of the method for producing an absorbent member of the present invention.

[Fig. 9] FIG. 9 is an enlarged side view of the second feed mechanism (fiber cluster producing apparatus) of the obtaining apparatus shown in FIG. eight.

Description of Embodiments

[0009] An absorbent body according to Patent Document 1 contains, in addition to water-absorbent cellulose fibers, synthetic fibers (thermoplastic resin fibers), thus having a higher rigidity than an absorbent body containing only water-absorbent cellulose fibers in as constituent fibers, and therefore should have superior performance, including cushioning and compression recovery properties. In the absorbent body, however, each of the plurality of synthetic fibers is contained independently rather than forming an aggregated cluster, and thus such properties are not sufficiently improved. Therefore, when incorporated into an absorbent article, the absorbent member is likely to curl and may not provide sufficient fit properties. In particular, after the absorption of body fluids such as urine and menstrual blood, such deficiencies are markedly noticeable.

[0010] Absorbent members according to Patent Documents 2 and 3 include aggregates of synthetic fibers that have undefined shapes as described above and come in a variety of shapes and sizes. Therefore, when such aggregates are mixed with wood pulp or the like, it is difficult to obtain a uniform mixture and the expected effects may not be achieved. In addition, the synthetic fiber aggregates disclosed in these Documents are produced by cutting a nonwoven fabric primarily containing synthetic fibers into small pieces, or by plucking or tearing such a nonwoven fabric, and thus are expected to have a non-uniformly uneven surface. . In an absorbent body containing a plurality of synthetic fiber aggregates having such a completely uneven surface, the plurality of synthetic fiber aggregates are entangled with each other over the entire surface by a relatively strong adhesive force. Therefore, the degree of freedom of movement of the synthetic fiber aggregates is noticeably limited, and the softness of the absorbent body deteriorates. When all of the synthetic fiber aggregates included in the absorbent are fused to each other as described in the preferred embodiment of the absorbent according to Patent Document 2, the movement of the fiber aggregates is limited, thus the absorbent has a higher overall hardness, and various properties, including flexibility, may be degraded.

[0011] As described in Patent Document 2, when all aggregates of synthetic fibers contained in an absorbent body are fused to each other, the flexibility of the absorbent body deteriorates and the fit properties of the absorbent article are not sufficiently improved. So far, no absorbent elements have been produced that contain aggregates of synthetic fibers and are able to satisfy such properties as flexibility and fit properties, as well as shape retention properties at a high level.

[0012] The present invention thus relates to an absorbent body that has excellent shape retention properties, flexibly deforms under external forces with high sensitivity, and can improve the wearing comfort and fit properties of an absorbent article including an absorbent body and to an absorbent article. including an absorbent element.

[0013] Hereinafter, the present invention will be described based on the preferred embodiments thereof with reference to the drawings. Fig. 1 shows an absorbent 100 as an embodiment of the absorbent of the present invention. The absorbent body 100 includes an absorbent core 10 that absorbs liquid and a liquid permeable core wrap layer 10W overlying the outer surface of the absorbent core 10. The absorbent core 10 is the main component of the absorbent core 100 and forms the outer shape of the absorbent body 100. The core wrap layer 10W serves, during manufacture of the absorbent body 100, as a layer for receiving raw materials of the absorbent core 10, and after manufacture serves to wrap the absorbent core 10 and to determine the shape, for example. The following description of the absorbent member 100 will be appropriately applied to the absorbent core 10, unless otherwise indicated (the term "absorbent member 100" can be appropriately replaced by "absorbent core 10").

[0014] The absorbent member 100 has an oblong shape in one direction in such a planar view as shown in FIG. 1(a), and more specifically, has a substantially rectangular shape with rounded corners. On FIG. 1(a), X indicates the longitudinal direction of the absorbent member 100, and Y indicates a transverse direction orthogonal to the longitudinal direction. When the absorbent element 100 is included in an absorbent article, the longitudinal direction X of the absorbent element 100 generally coincides with the front-to-back direction (direction from the abdomen through the crotch region to the back) of the wearer of the absorbent article.

[0015] The core wrapping layer 10W covers the skin-facing surface and the non-skin-facing surface of the absorbent core 10. The absorbent core 10 and the core wrapping layer 10W may be bonded with an adhesive such as a hot melt adhesive. As used herein, the “skin-facing surface” is one surface of the absorbent article or its constituent element (e.g., absorbent core) and is facing the wearer’s skin while the absorbent article is being worn, or is the side relatively close to the wearer’s skin, and “not "skin-facing surface" is the other surface of the absorbent article or a constituent thereof and faces away from the wearer's skin when the absorbent article is worn (garment side), or is the side relatively far away from the wearer's skin. In the present description, “during wearing” means a state in which a typical, suitable to wear, position is maintained.

[0016] In the absorbent body 100, the core wrapping layer 10W is one continuous core wrapping layer 10W having a width that is two times or more and three or less times the size of the absorbent core 10 in the transverse direction Y. The 10W core wrapping layer, shown separately in FIG. 1(b) covers the entire area of the skin-facing surface of the absorbent core 10 and extends from the respective side edges of the absorbent core 10 along the longitudinal direction X outward in the transverse direction Y, and the elongated portions are folded under the absorbent core 10 and cover the entire non-skin-facing area. surface of the absorbent core 10. The configuration of the 10W core wrapping layer is not limited to the above. For example, the core cover layer may include a skin-facing core cover layer lying on the skin-facing surface of the absorbent core 10 and a non-skin-facing core cover layer lying on the non-skin-facing surface of the absorbent core 10, and the two layers may be separate layers. As the 10W core wrapping layer, for example, paper or non-woven material can be used.

[0017] The absorbent core 10 includes fiber clusters 11 containing a plurality of 11F fibers and includes 12F water absorbent fibers as shown in FIG. 1(b). The constituent fibers 11F of the fiber cluster 11 include at least thermoplastic fibers. In the present description, a "cluster of fibers" is a collection of fibers, where a plurality of fibers are collected into one. Examples of the shape of the fiber cluster include a sheet piece obtained by separating a synthetic fiber sheet having a certain size. In particular, the fiber cluster is preferably a piece of nonwoven material obtained by cutting the nonwoven material selected as the synthetic fiber sheet to a predetermined size and shape. The fiber cluster 11 is an integrated fiber aggregate in which the 11F fibers are purposefully accumulated in a cluster, while the 12F water-absorbent fibers are not purposefully integrated, but can each be independently contained in the absorbent core 10. The fiber clusters 11 mainly contribute to the improvement flexibility, cushioning properties, compression recovery properties, shape retention properties, and the like. absorbent member 100. Water-absorbent fibers 12F mainly contribute to improving liquid absorption capacity, shape retention properties, and the like. absorbent element 100.

[0018] As described above, the fiber cluster in the form of a sheet piece as a preferred embodiment of the fiber cluster of the present invention is not obtained by accumulating a plurality of fibers to form a sheet piece, but is obtained by cutting a fibrous sheet (preferably a nonwoven fabric) having a larger size, than a piece of sheet (see Fig. 6). The plurality of fiber clusters included in the absorbent of the present invention are a plurality of fiber clusters in the form of sheet pieces having a more defined shape than those made in the conventional manner as described in Patent Documents 2 and 3.

[0019] The absorbent core 10, as shown in FIG. 1 includes, in the direction of the plane of the absorbent core 10 (i.e., in the direction of the plane of the absorbent member 100), first zones 15 in which a plurality of fiber clusters 11 are fused together, and a second zone 16 in which a plurality of fiber clusters 11 are not fused, but intertwined with each other. At least in the second zone 16, the fiber clusters 11 are intertwined with the water-absorbing fibers 12F. The method of bonding between clusters of fibers 11 in the first zone 15 is "fusion" as a thermal fusion between the constituent fibers 11F, while in the second zone 16 this method is "interlacing" mainly by entanglement of the constituent fibers 11F. Due to the difference in binding method, the degree of freedom of movement of fiber clusters 11 in the second zone 16 is higher than in the first zone 15. In other words, the fiber clusters 11 in the first zone 15 are relatively difficult to move, while the fiber clusters 11 in the second zone 16 are relatively easy to move. mobile. Due to the nature of the zones 15, 16, the first zone 15 may also be referred to as the “restricted fiber cluster mobility zone”, while the second zone 16 may also be referred to as the “flexible fiber cluster zone”.

[0020] In the absorbent body 100, the first zone 15 has a rectangular shape, a plan view of which is shown in FIG. 1(a), and two lines of first zones are formed around the center in the transverse direction Y on the skin-facing surface of the absorbent body 100, while the longitudinal direction of the rectangular shape coincides with the longitudinal direction X of the absorbent body 100. On the non-skin-facing surface of the absorbent element 100 (absorbent core 10), the first zone 15 is not formed. The two lines of the first zones 15, 15 have the same shape and the same size, are parallel to each other at a predetermined interval in the transverse Y direction of the absorbent body 100, and are symmetrically formed about an imaginary center line (not shown) extending in the longitudinal X direction and bisecting the absorbent element 100 in the transverse Y direction. Each first zone 15 extends through the center of the absorbent element 100 in the longitudinal X direction, but does not reach the ends of the absorbent element 100 in the longitudinal X direction. longitudinal direction.

[0021] The second zone 16 is a zone different from the first zones 15 of the absorbent element 100 and, in the absorbent element 100, is located in the peripheral zone of the absorbent element 100 and between the two first zones 15, 15, as shown in FIG. 1(a). In other words, each of the plurality of first zones 15 in the absorbent member 100 is surrounded by a second zone 16.

[0022] FIG. 2 is a schematic three-dimensional representation of a portion of the second zone 16. Symbol 11Z in FIG. 2 denotes the overlapping portion of the plurality of fiber clusters 11. In the second zone 16, the plurality of fiber clusters 11 are not fused but intertwined with each other as described above, and thus these fiber clusters 11 are loosely bonded, making them literally movable, and form one solid body consisting of clusters of fibers. In the second zone 16, the fiber clusters 11 included in the single solid fiber cluster body are intertwined with the water absorbent fibers 12F, and the water absorbent fibers 12F are intertwined and loosely bonded to the fiber cluster solid body. In the second zone 16, typically, a plurality of water-absorbing fibers 12F are also intertwined with each other. At least some of the plurality of fiber clusters 11 in the second zone 16 are interwoven with other fiber clusters 11 or with water-absorbent fibers 12F. In the absorbent member 100, all of the plurality of fiber clusters 11 in the second zone 16 may be intertwined with each other to form, in some cases, one solid body of fiber clusters, or in some cases, a plurality of solid bodies of fiber clusters. , can be mixed in the non-binding state. The weaving property of fiber clusters 11, i.e. the mere formation of weaving fiber clusters 11 with other fiber clusters 11 or water-absorbing fibers 12F depends largely on the configuration (number, size, distribution state, etc.) of the protruding portion of fiber 113, described later, of fiber cluster 11, and the proper controlling the configuration of the protruding portion of the fiber 113 can improve the weaving property of the fiber clusters 11.

[0023] FIG. 3 schematically shows a deformation state when the second zone 16 is in the natural state (non-impacted state) shown in FIG. 2 is compressed by an external force F. The second zone 16, in which the clusters of fibers 11 in the form of aggregates of fibers are mixed with the water-absorbing fibers 12F in the form of non-aggregates fibers, seems to be bent especially at the boundaries BL between the elements 11, 12F, (dotted lines in Fig. 2) due to the difference in stiffness between the elements 11, 12F, and the boundaries BL function as bending parts when the second zone 16 is deformed. Boundaries BL as bendable parts are generally located over the entire area of the second zone 16, thus the second zone 16 deforms flexibly due to various external forces with high sensitivity and can immediately recover to its original state due to the compression recovery properties of the fiber clusters 11 when the external the effort is weakened. Such deformation-recovery properties of the second zone 16 may be exhibited not only when the second zone 16 is compressed, but also when the second zone is deformed. For example, when incorporated into an absorbent article such as sanitary napkins, the absorbent member 100 is typically positioned to be positioned between the thighs of the wearer of the absorbent article, and thus the absorbent member 100 may curve about an imaginary axis of rotation extending in the front direction. back at the user, as the user's hips move as the user walks. Even so, the second zone 16, which has high deformation-recovery characteristics, is easily deformed/recovered in accordance with such an external force, contributing to the curvature from the hips, thus is unlikely to twist and can give the absorbent article high body-fitting characteristics. user.

[0024] The fiber clusters 11 have excellent flexibility or the like, and thus the absorbent member including the fiber clusters potentially has excellent flexibility or the like as in the second zone 16. In the present invention, the fiber clusters 11 are bonded to each other. with another or with the water-absorbent fibers 12F by interlacing, thus the sensitivity to external forces is further improved and the absorbent member 100 has sufficient shape-retaining properties. However, external forces are applied in various directions to the absorbent in an absorbent article, and in some cases such a strong external force may be applied that results in the destruction of the absorbent. Therefore, the absorbent body preferably has such high shape retention characteristics as to prevent the absorbent body from breaking even in such a case.

[0025] Therefore, the absorbent body 100 has the following structure in order to satisfy properties such as flexibility and fit properties and shape retention properties at high levels: as shown in FIG. 1, the absorbent has, in addition to the second zone 16 in which the plurality of fiber clusters 11 are not fused but intertwined with each other, first zones 15 in which the plurality of fiber clusters 11 are fused with each other. The first zone 15 is typically formed by subjecting the second zone 16 to a heat treatment whereby the constituent fibers 11F of the plurality of fiber clusters 11 in the second zone 16 are melted and the plurality of fiber clusters 11 are bonded to each other by melting. The heat treatment of the second zone 16 can be carried out by known embossing techniques such as hot embossing and ultrasonic embossing.

[0026] The first zone 15 formed by heat treatment with compression of the absorbent element, such as the above embossing, has a higher density than the density of other parts without such pressing (the second zone 16) of the absorbent element 100. In other words, the first zone 15 may be part with a high density having a relatively high density, and the second zone 16 may be a low density part having a relatively low density.

[0027] In the first zone 15, unlike the second zone 16, a plurality of fiber clusters 11 are firmly bonded by fusion to form a single continuous body of fiber clusters, and each fiber cluster 11 that constitutes a single continuous body of fiber clusters, has a lower degree of freedom of movement than in the second zone 16. As the degree of fusion increases, each fiber cluster 11 in the first zone 15 can hardly move. Each cluster of fibers 11 constituting a single continuous body of the fiber cluster in the first zone 15 is substantially attached to the second zone 16. The absorbent member 100 includes both the first zone 15 and the second zone 16, as described above, in the direction of the plane (the direction in which the skin-facing surface or non-skin-facing surface) orthogonal to the thickness direction, so that the first zone 15 can withstand the compression force in the plane direction, and the second zone 16 provided around the first zone can weaken the compression force applied to the first zone 15 From this point of view, the second zone 16 is preferably provided on the outside of the first zone 15 in the direction of the plane of the absorbent member 100. Thus, the absorbent member 100 has such high shape retention characteristics as the ability to withstand the high compression force described above, it is difficult to break, and it can stably show beneficial effects (flexibility improvement effects, cushioning properties, compression recovery properties, anti-curl properties, etc.) due to the presence of the second zone 16.

[0028] The configurations (flat shape and arrangement) of the first zone 15 can be designed so that both properties, such as flexibility and fit properties and shape retention properties, are satisfied at a high level. In terms of design, when incorporated into an absorbent article, the absorbent member 100 is typically positioned such that the center portion of the absorbent member 100 in the longitudinal X direction is positioned between the thighs of the wearer of the absorbent article, and thus the center portion of the absorbent member 100 in the longitudinal X direction. is likely to be subjected to a relatively strong external force and may collapse. Considering this, as shown in Fig. 1, the first zone 15 is preferably located at least in the central part of the absorbent member 100 in the longitudinal X direction (the portion corresponding to the discharge receiving portion of the user wearing the absorbent article).

[0029] Regarding the configuration of the first zone 15 in the absorbent body 100, the first zones 15 and the second zones 16 are arranged alternately in the direction of the plane of the absorbent body 100, more specifically in the transverse Y direction, as shown in FIG. 1. When the zones 15, 16 are arranged alternately in the plane direction as described above, properties such as flexibility and fit properties and shape retention properties are most likely to be achieved. In the absorbent body 100, the region with the alternating zones 15, 16 is located in the central part in the longitudinal direction X, generally corresponding to the part between the thighs of the wearer wearing the absorbent article, thus the absorbent body 100 can be flexibly deformed in accordance with the strong external force applied by the thighs. , and can immediately recover to its original state when the external is weakened. In the absorbent body 100, each edge portion in the transverse Y direction of the zone-alternating region 15, 16 is a second zone 16 having a relatively high flexibility, and thus the absorbent body 100 can come into contact with the hips with satisfactorily damping properties and can significantly improve the wearing comfort of the absorbent article.

[0030] From the viewpoint of being more likely to exhibit the above beneficial effects, each part of the absorbent member 100 preferably has the following dimensions and the like.

The width W15 of the first zone 15 (see FIG. 1(a)) is preferably 0.5% or more, more preferably 1% or more, and even more preferably 2% or more, and is also preferably 15% or less, more preferably 10% or less, and even more preferably 8% or less of the total lateral Y dimension of the absorbent member 100.

The length L15 of the first zone 15 (see Fig. 1(a)) is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more, and is also preferably 100% or less, more preferably 90% or less, and even more preferably 80% or less of the total dimension in the longitudinal direction X of the absorbent member 100.

[0031] The first zone 15 is preferably located on the inside of the corresponding side edge of the absorbent member 100 along the longitudinal X direction, and the second zone 16 is preferably located on the outside of the corresponding first zone 15 in the transverse Y direction, since resistance to compression forces from the outside in the transverse direction can be improved. Y.

The distance P1 between the side edge of the absorbent 100 along the longitudinal direction X and the corresponding first zone 15 (see Fig. 1(a)) is preferably 1 mm or more, more preferably 5 mm or more, even more preferably 8 mm or more, and is preferably 30 mm or less, more preferably 25 mm or less, even more preferably 20 mm or less.

The distance P2 between the first zones 15 adjacent in the transverse direction Y of the absorbent body 100 (see Fig. 1(a)) is preferably 5 mm or more, more preferably 8 mm or more, even more preferably 10 mm or more, and is preferably 60 mm or less, more preferably 50 mm or less, even more preferably 45 mm or less.

[0032] FIG. 4 shows exemplary configurations (planar shapes and arrangements) of the first zones 15. The configuration of the first zone 15 is not limited to those shown in FIG. 1 and FIG. 4 and may be any configuration without departing from the scope and spirit of the present invention.

In the absorbent member 100A shown in FIG. 4(a), a plurality of first zones 15 having a circular shape in planar form are scattered in the plane direction. More specifically, in the absorbent member 100A, a plurality of first zones 15 having a circular shape in planar form are staggered across the entire skin-facing surface of the absorbent member 100A, and each first zone 15 having a circular shape is surrounded by a second zone 16. The planar shape of the first the staggered zones 15 shown in FIG. 4(a) is not specifically limited, and any shape may be provided. Examples of the shape include, in addition to the round shape, an elliptical shape, a square shape, a diamond shape, and polygonal shapes including a pentagonal shape or more corners.

[0033] For the configuration of the first zone 15 shown in FIG. 4(a), with respect to each of the longitudinal direction X and the transverse direction Y, the distance between the centers of adjacent first zones 15, or the pitch between the nearest two first zones 15, 15, is preferably 2.0 mm or more, more preferably 3.5 mm or more, and is preferably 12 mm or less, more preferably 10 mm or less.

The number of the first zones 15 per any unit area of 10 square mm in planar form on the surface of the absorbent member 100A is preferably 2 or more, more preferably 5 or more, and is preferably 10 or less, more preferably 8 or less.

The maximum size of the first zone 15 in planar form is preferably 0.5 mm or more, and more preferably 1 mm or more, and is preferably 8 mm or less, and more preferably 6 mm or less. In the present description, the maximum dimension is the diameter when the planar shape of the first zone 15 is circular as shown in FIG. 4(a).

[0034] In the absorbent member 100B shown in FIG. 4(b), one first zone 15 having a rectangular planar shape is located in the central portion in both directions of the longitudinal direction X and the transverse direction Y. The longitudinal direction of the first zone 15 having a rectangular planar shape coincides with the longitudinal direction X absorbent element 100B. The absorbent member 100B may generally have substantially the same benefits as the absorbent member 100 shown in FIG. 1. Specifically, when the absorbent member 100B is included in the absorbent article and externally subjected to such a strong external force in the lateral Y direction, such as a large compressive force from the hips of the user wearing the absorbent article, the absorbent member 100B dissipates the external force in the second zone 16 located on of each edge portion of the absorbent member 100B in the lateral Y direction, and unintentional deformation of the center portion in the lateral Y direction can be effectively suppressed. As a result, the fit properties and wearing comfort of the absorbent article can be greatly improved.

[0035] In the absorbent member 100C shown in FIG. 4(c) and the absorbent member 100D shown in FIG. 4(d), the linear first zones 15 are planarly distributed so that they extend in predetermined directions. In the absorbent body 100C, the continuous straight line like first zones 15 extending in the longitudinal X direction are distributed to be orthogonal to the continuous straight line like first zones 15 extending in the transverse Y direction, and the first zones 15 form a grid pattern as one whole. The absorbent body 100D is essentially the same as the absorbent body 100C, except that the extension directions of the continuous straight-line-like first zones 15 intersecting with each other are directions intersecting the longitudinal direction X and the transverse direction Y. In the absorbent body 100C and absorbent body 100D, the area surrounded by linear first zones 15 intersecting with each other (mesh) is the second zone 16, and a large number of second zones 16 are evenly distributed throughout the absorbent body. Therefore, these absorbent members can satisfy both properties, such as flexibility and fit properties and shape retention properties, at a high level. In the lateral Y direction, the second zones 16 are distributed in the edge parts of the absorbent body 100C, 100D in the plane direction, and the first zones 15 are located on the inside of the edge parts in the lateral Y direction. outside in the transverse Y direction (shape-keeping properties).

[0036] In the absorbent member 100E shown in FIG. 4(e), the first zones 15 are distributed only in the side edge portions along the longitudinal direction X, and the other area including the center portion in the transverse Y direction of the absorbent 100E is the second zone 16. In each side edge portion along the longitudinal direction X of the absorbent element 100E, a plurality of first zones 15 having a rectangular shape (like a short straight line shape) in a planar view are discontinuously distributed in the longitudinal direction X, and each first zone 15 extends in a direction intersecting both the longitudinal direction X and the transverse direction Y. The second zone 16 in the absorbent member 100E is formed symmetrically about an imaginary center line (not shown) that bisects the absorbent member 100E in the longitudinal X direction. forms, and includes the second zone 16 at high filling to have particularly excellent flexibility, and the like. In the lateral Y direction, the second zone 16 is provided in the edge portions of the absorbent body 100E in the plane direction, and the first zone 15 is provided on the inside of the edge portions in the lateral Y direction. Y (shape retention properties).

[0037] The first zone 15 is preferably provided at a position corresponding to the hips of the wearer, with respect to the longitudinal direction X of the absorbent element 100. In the absorbent element 100, the position corresponding to the hips of the user varies depending on the types of absorbent article including the absorbent element 100. For example, when absorbent element 100 is included as a constituent element in a sanitary napkin, the first zone 15 is preferably provided in a position facing the discharge site at the user, in the longitudinal direction X of the absorbent element 100. When the absorbent element 100 is included as a constituent element in a disposable diaper, the first zone 15 is preferably provided in a position facing the user's urinary tract, in the longitudinal direction X of the absorbent member 100.

[0038] The proportion of the total area of the first zones 15 in the total area of one face (facing the skin surface) of the absorbent element 100, first/last, is preferably 0.1% or more, more preferably 0.5% or more, even more preferably 1% or more, and preferably 20% or less, more preferably 15% or less, even more preferably 10% or less.

[0039] The thickness 15T of the absorbent core 10 in the first zone 15 (see Fig. 1(b)) is preferably 0.1 mm or more and more preferably 0.2 mm or more, and is preferably 2 mm or less and more preferably 1 mm or less.

The thickness 16T of the absorbent core 10 in the second zone 16 (see FIG. 1(b)) is preferably 0.8 mm or more and more preferably 1.5 mm or more, and is preferably 10 mm or less and more preferably 6 mm or less.

The ratio of the 15T thickness to the 16T thickness, first/last, is preferably 0.01 or more, and more preferably 0.02 or more, and is preferably 0.8 or less, and more preferably 0.5 or less. The thickness values of 15T and 16T are determined according to the <Absorbent Member Thickness Measurement Method> described later.

[0040] In the second zone 16 of the absorbent member 100, the fiber clusters 11 are intertwined with each other or with the water absorbent fibers 12F. In the present description, "weaving" fiber clusters 11 and the like. includes the following configuration A.

Configuration A: Clusters of fibers 11, etc. connected without fusion, but with the interlacing of the constituent fibers 11F of fiber clusters 11.

Configuration B: When the absorbent body 100 is in its natural state (without any external force), the fiber clusters 11 and the like. not bonded, but when an external force is applied to the absorbent member 100, the fiber clusters 11 and the like. may be bonded by interlacing constituent 11F fibers. In this configuration, the "external force that is applied to the absorbent member 100" is that, for example, a deforming force is applied to the absorbent member 100 when an absorbent article including the absorbent member 100 is worn.

As described above, in the absorbent body 100, the fiber clusters 11 are bonded to other fiber clusters 11 or to the water-absorbent fibers 12F by fiber entanglement or "weave" as in configuration A, and the fiber clusters 11 may be bonded to other fiber clusters 11 or to with water-absorbent fibers 12F by interlacing as in configuration B. This bonding by interlacing the fibers is important for the above benefits of the absorbent member 100 to be more effectively manifested.

[0041] In the absorbent element 100 (second zone 16), the overall type of bonding through the fiber clusters 11 is not necessarily limited to “weave”, and the absorbent element 100 (second zone 16) may partially include additional types of bonding other than weaving, such as bonding with the help of an adhesive.

[0042] However, in the remainder of the absorbent body 100, with the exception of the "fusion through fiber clusters 11" formed in the absorbent body 100 by integration with other elements of the absorbent article, such as recesses including non-leakage grooves of the absorbent article, i.e., in the absorbent article itself. absorbent body 100, bonding between fiber clusters 11 or bonding between fiber clusters 11 and water-absorbing fibers 12F is preferably only formed by “fiber entanglement”.

[0043] From the point of view of making the absorbent body 100 more likely to exhibit the above beneficial effects, the total number of "interlaced fiber clusters 11" in configuration A and "interlacable fiber clusters 11" in configuration B is preferably 50% or more, more preferably 70% or more, and even more preferably 80% or more, relative to the total number of fiber clusters 11 in the absorbent body 100.

From the same point of view, the number of "weave" fiber clusters 11 in configuration A is preferably 70% or more, preferably 80% or more of the total number of fiber clusters 11 associated with other fiber clusters 11 or with water-absorbing fibers 12F.

[0044] The main characteristic of the absorbent element 100 is the external shape of the fiber cluster 11. FIG. 5 shows two exemplary outer shapes of the fiber cluster 11. The fiber cluster 11A shown in FIG. 5(a) is in the shape of a square prism, more specifically, in the shape of a cuboid, while the fiber cluster 11B shown in FIG. 5(b) is disc-shaped. Clusters of fibers 11A and 11B typically have two opposing base surfaces 111 and skeleton surfaces 112 connecting the two base surfaces 111. Each of the base surfaces 111 and skeleton surfaces 112 is substantially free of asperities at the level of assessing asperities on the surface of an article primarily containing this kind fibers.

[0045] The cuboid fiber cluster 11A in FIG. 5(a) has six flat surfaces. Of the six surfaces, the two opposite surfaces having the maximum area are base surfaces 111, and the remaining four surfaces are wireframe surfaces 112. The base surfaces 111 intersect, more specifically, orthogonal to the wireframe surfaces 112.

The disc-shaped cluster of fibers 11B in FIG. 5(b) has two opposite flat surfaces having a circular shape in planar form and a curved circular surface connecting the flat surfaces. The two flat surfaces are the base surfaces 111 and the circular surface is the frame surface 112.

The fiber clusters 11A and 11B are similar in that the frame surfaces 112 are rectangular in planar form, more specifically, rectangular in shape.

[0046] The plurality of fiber clusters 11 contained in the absorbent body 100 differ from the piece of nonwoven fabric or microfiber material according to Patent Documents 2 and 3 as an indefinite collection of fibers in that each fiber cluster is a “defined collection of fibers” having two opposing base surfaces 111 and frame surfaces 112 connecting base surfaces 111, as in fiber clusters 11A and 11B shown in FIG. 5. In other words, when viewing a cluster of fibers 11 arbitrarily selected from among the clusters of fibers 11 contained in the absorbent member 100 (for example, observed under an electron microscope), the perspective shape of the cluster of fibers 11 varies depending on the viewing angles, and a single cluster of fibers 11 gives a large number of promising forms. Each of the plurality of fiber clusters 11 in the absorbent body 100 has, as one of a large number of perspective shapes, a particular perspective shape having two opposing base surfaces 111 and frame surfaces 112 connecting the base surfaces 111. The plurality of pieces of nonwoven material or microfibers contained in absorbent members according to Patent Documents 2 and 3, essentially do not have such a "surface" as the base surface 111 or the frame surface 112, i.e. extending part, have different external shapes and do not have a “defined shape”.

[0047] As described above, when the plurality of fiber clusters 11 contained in the absorbent body 100 are "defined fiber aggregates" formed by the base surfaces 111 and the frame surfaces 112, the uniform dispersibility of the fiber clusters 11 in the absorbent body 100 is improved compared to such undefined fiber aggregates as described in Patent Documents 2 and 3. Therefore, effects (effects of improving flexibility, damping properties, compression recovery properties, and the like of an absorbent body) to be exhibited when fiber aggregates such as fiber clusters are stably achieved 11 are contained in the absorbent member 100. In particular, such a cluster of fibers 11 having the shape of a cuboid as shown in FIG. 5(a), which has, as outer surfaces, six surfaces, including two base surfaces 111 and four frame surfaces 112, may come into contact with other fiber clusters 11 or water-absorbent fibers 12F more frequently than such a disk-shaped fiber cluster 11 , having three outer surfaces as shown in FIG. 5(b). Accordingly, the weaving property is improved, and the shape retention properties or the like can also be improved.

[0048] In the fiber cluster 11, the total area of the two base surfaces 111 is preferably greater than the total area of the frame surfaces 112. In other words, in the cuboid-shaped fiber cluster 11A in FIG. 5(a), the sum of the areas of the two base surfaces 111 is larger than the sum of the areas of the four frame surfaces 112, and in the disc-shaped fiber cluster 11B in FIG. 5(b), the sum of the areas of the two base surfaces 111 is larger than the area of the frame surface 112 forming the circular surface of the disc-shaped fiber cluster 11B. In each of the fiber clusters 11A and 11B, the base surface 111 has the largest area of the multiple surfaces of the fiber cluster 11A or 11B.

[0049] A cluster of fibers 11, such as a "defined collection of fibers", formed by two base surfaces 111 and carcass surfaces 112 intersecting the base surfaces 111, can be obtained in a way different from conventional technologies. The preferred way to obtain a cluster of fibers 11, as shown in FIG. 6 is to cut the fibrous material sheet 10bs (a sheet having the same composition as the fiber cluster 11 but having a size larger than the fiber cluster 11) as a starting material using cutting means such as a cutter into a certain shape. . The plurality of resulting fiber clusters 11 have a more defined shape and size than those produced by the conventional methods described in Patent Documents 2 and 3. FIG. 6 is an illustration of a method for obtaining fiber clusters 11A having the cuboid shape shown in FIG. 5(a) and dotted lines in FIG. 6 indicate cut lines. The absorbent core 10 includes a plurality of fiber clusters 11 having the same shape and size and made by cutting a fibrous sheet material into a specific shape, as described above. The sheet fibrous material 10bs is preferably a non-woven material as described above.

[0050] The cuboid fiber cluster 11A in FIG. 5(a) is obtained by cutting the fiber sheet 10bs in the first direction D1 and the second direction D2 intersecting (more specifically orthogonal) the first direction D1 into predetermined lengths as shown in FIG. 6. Each of the directions D1 and D2 is a predetermined direction in the plane direction of the sheet 10bs, and the sheet 10bs is cut along the Z thickness direction orthogonally to the plane direction. On a plurality of cuboid-shaped fiber clusters 11A obtained by cutting the fiber sheet 10bs into so-called squares in this way, the cut surface, i. the surface in contact with cutting means such as a cutter, when the sheet 10bs is cut, is the frame surface 112, and the uncut surface, that is, the surface not in contact with the cutting means, is the reference surface 111. The reference surface 111 is is the top or bottom surface (a surface orthogonal to the thickness Z direction) of the sheet 10bs and has the largest area of the plurality of surfaces of the fiber cluster 11A as described above.

[0051] The above description of fiber cluster 11A can essentially be applied to the disc-shaped fiber cluster 11B in FIG. 5(b). The essential difference from the fiber cluster 11A is only the cutting shape of the fibrous material sheet 10bs, and in order to cut the sheet 10bs into a certain shape to obtain fiber clusters 11B, the sheet 10bs can be cut into a round shape corresponding to the shape of the fiber cluster 11B in a planar view.

[0052] The outer shape of the fiber cluster 11 is not limited to the shapes shown in FIG. 5, and each of base surface 111 and frame surface 112 may be a flat, non-curved surface such as surfaces 111 and 112 in FIG. 5(a), or may be a curved surface such as the carcass surface 112 (circular surface of the disc-like fiber cluster 11B) in FIG. 5(b). The base surface 111 and the frame surface 112 may have the same shape and the same size. Specifically, the outer shape of the fiber cluster 11A may be a cubic shape, for example.

[0053] As described above, the two types of surfaces (base surface 111 and skeleton surface 112) of the fiber cluster 11 (11A or 11B) include a cut surface (skeleton surface 112) formed by cutting the fibrous material sheet 10bs with a cutting means such as a cutting machine when the fiber clusters 11 are obtained, and the uncut surface (base surface 111), that is, the original surface of the sheet 10bs and not in contact with the cutting means. Due to the difference between the cut surface and the uncut surface, the frame surface 112 as the cut surface generally has more fiber ends per unit area than the base surface 111 as the uncut surface. In the description, “fiber end” means the end in the length direction of the constituent fiber 11F of the fiber cluster 11. Although the base surface 111 generally includes fiber ends as an uncut surface, the frame surface 112, which is the cut surface formed by cutting the fiber sheet 10bs, includes , over the entire frame surface 112, a large number of fiber ends as cut ends of the constituent fibers 11F formed by cutting, and thus has a greater number of fiber ends per unit area than the base surface 111.

[0054] The ends of the fibers on each surface (base surface 111 and frame surface 112) of the fiber cluster 11 are advantageous when the fiber cluster 11 forms an interweaving with other fiber clusters 11 or water-absorbent fibers 12F contained in the absorbent body 100. Typically, more ends fibers per unit area can improve the weave property, and thus can improve various characteristics such as the shape retention properties of the absorbent member 100. As described above, the surfaces of the fiber cluster 11 have a different number of fiber ends per unit area, and the number of fiber ends per unit area satisfies the relationship "frame surface 112 > base surface 111". Therefore, the interweaving property through the fiber cluster 11 with other fibers (other fiber clusters 11 and water-absorbing fibers 12F) varies depending on the surfaces of the fiber cluster 11, and the carcass surface 112 has a higher weave property compared to the base surface 111. In other words, the binding by interlacing with other fibers through the carcass surface 112 is stronger than through the base surface 111, and one cluster of fibers 11 has a difference in adhesive strength between the base surface 111 and the carcass surface 112.

[0055] As described above, each of the plurality of fiber clusters 11 contained in the absorbent member 100 is intertwined with other peripheral fibers (other fiber clusters 11 and water-absorbent fibers 12F) with two kinds of cohesive forces, and accordingly, the absorbent member 100 has and appropriate softness and strength (shape retention properties). In addition, when the absorbent member 100 having such excellent performance is used as an absorbent member in an absorbent article in a conventional manner, the absorbent article can provide wearing comfort to its user and can effectively prevent the disadvantage that the absorbent member 100 is destroyed by external forces, including the pressure of the user's body while wearing.

общую площадь, чем общая площадь каркасных поверхностей 112, как описано выше. Это означает, что базовые поверхности 111, имеющие относительно небольшое количество концов волокон на единицу площади и, соответственно, имеющие относительно низкое свойство переплетения с другими волокнами, имеют

общую площадь, чем у каркасных поверхностей 112, имеющих характеристики, противоположные этому. Поэтому вероятно будет предотвращаться переплетение кластера волокон 11 (11A или 11B), показанного на Фиг. 5, с другими периферическими волокнами (другими кластерами волокон 11 и впитывающими воду волокнами 12F) по сравнению с кластерами волокон, имеющими концы волокон равномерно по всей поверхности. Даже если он переплетается с другими периферическими волокнами, кластер волокон вероятно будет переплетаться со сравнительно небольшой силой сцепления, таким образом, вряд ли он будет образовывать большой агрегат и сможет придать превосходную гибкость впитывающему элементу 100.[0056] In particular, on the cluster of fibers 11 (11A or 11B) shown in FIG. 5, two base surfaces 111 have

total area than the total area of the frame surfaces 112 as described above. This means that the base surfaces 111, having a relatively small number of fiber ends per unit area and, accordingly, having a relatively low interweaving property with other fibers, have

total area than the frame surfaces 112 having the opposite characteristics. Therefore, interweaving of the fiber cluster 11 (11A or 11B) shown in FIG. 5 with other peripheral fibers (other fiber clusters 11 and water-absorbing fibers 12F) compared to fiber clusters having fiber ends uniformly over the entire surface. Even if it is intertwined with other peripheral fibers, the fiber cluster is likely to be intertwined with relatively little cohesive force, thus it is unlikely to form a large aggregate and be able to impart excellent flexibility to the absorbent body 100.

[0057] In contrast, a piece of nonwoven fabric or microfiber material according to Patent Documents 2 and 3, which is obtained, for example, by cutting a sheet fibrous material with a cutting machine, such as a cutter, into pieces of indefinite shape, as described above , is not a specific cluster of fibers in the form of a piece of sheet having "surfaces" such as the base surface 111 and the frame surface 112. Moreover, during manufacture, an external cutting force is applied to the entire cluster of fibers, thus, the ends of the fibers constituting the cluster of fibers are formed randomly throughout the cluster of fibers, and the beneficial effects of fiber ends described above are unlikely to be sufficiently achieved.

[0058] In terms of greater likelihood of achieving the above beneficial effects of fiber ends, the ratio of the number of fiber ends per unit area on the base surface 111 (uncut surface), N ₁ , to the number of fiber ends per unit area on the frame surface 112 (cut surface), N ₂ , N ₁ /N ₂ is preferably 0 or more and more preferably 0.05 or more, and is preferably 0.90 or less and more preferably 0.60 or less, provided that N ₁ < N ₂ . More specifically, N ₁ /N ₂ is preferably 0 or more and 0.90 or less, and more preferably 0.05 or more and 0.60 or less.

The number of fiber ends per unit area on the base surface 111, N ₁ , is preferably 0 fiber ends/mm ² or more, and more preferably 3 fiber ends/mm ² or more, and preferably 8 fiber ends/mm ² or less, and more preferably 6 fiber ends/mm ² or less.

The number of fiber ends per unit area on the carcass surface 112, N _2, is preferably 5 end portions of the fibers / mm ² or more, and more preferably 8 the end portions of the fibers / mm ² or more, and preferably 50 end portions of the fibers / mm ² or less, and more preferably 40 fiber ends/mm ² or less.

The number of fiber ends per unit area on the base surface 111 or frame surface 112 is determined in the following way.

[0059] <Method for measuring the number of fiber ends per unit area on each surface of a fiber cluster>

The element (fiber cluster) containing the fibers to be measured (measurement sample) was attached to the sample table with double-sided adhesive paper tape (NICETACK NW-15, manufactured by Nichiban Co., Ltd.). The sample to be measured is then coated with platinum. The ion sprayer E-1030 (trade name) manufactured by Hitachinaka Seiki Co., Ltd was used for coating, and the spray time was set to 120 seconds. The cut surfaces (base surface and frame surface) of the measurement sample are observed under an electron microscope, JCM-6000 manufactured by JEOL, at a magnification of 100x. A rectangular area having a length of 1.2 mm and a width of 0.6 mm is set in the observed image at a magnification of 100× at any position on the surface to be measured (base surface and wireframe surface), and the viewing angle, etc. adjusted so that the area of the rectangular area is 90% or more of the area of the observed image. Then count the number of fiber ends in a rectangular area. When the measurement surface of the fiber cluster is smaller than 1.2 mm × 0.6 mm in the observed image at 100× magnification, and the proportion of the area of the rectangular area in the total area of the observed image is less than 90%, the observation magnification is set to greater than 100× and the number fiber ends in a rectangular area on the measured surface are counted in the same way. In the description, the “fiber ends” to be counted are the ends in the length direction of the constituent fibers of the fiber cluster, and even when parts other than the ends in the length direction of the constituent fibers (intermediate parts in the length direction) extend from the surface to be measured, the intermediate parts in length direction are excluded from the calculation. The number of fiber ends per unit area on the measurement surface of the fiber cluster ((base surface and skeletal surface) is then calculated according to the following formula. For each of 10 fiber clusters, the number of fiber ends per unit area on each of the base surface and skeleton surface is counted according to with the above procedure, and calculate the average of the calculated quantities as the number of fiber ends per unit area on the measured surface.

Number of fiber ends per unit area on the measurement surface of the fiber cluster (base surface and frame surface) (number/mm ² ) = number of fiber ends contained in a rectangular area (1.2×0.6 mm)/area of a rectangular area (0. 72 mm ² )

[0060] When the base surface 111 of the fiber cluster 11 is rectangular in planar form, as in the fiber cluster 11A shown in FIG. 5(a), the short side 111a of the rectangular shape is preferably equal to or shorter than the thickness of the absorbent body 100 containing the fiber cluster 11 (11A) from the viewpoint of improving the uniform dispersibility of the fiber clusters 11 in the absorbent body 100.

The ratio of the length of the short side 111a to the thickness of the absorbent member 100, first/last, is preferably 0.03 or more, more preferably 0.08 or more, and preferably 1 or less, more preferably 0.5 or less.

The thickness of the absorbent member 100 is preferably 1 mm or more, and more preferably 2 mm or more, and preferably 15 mm or less, more preferably 10 mm or less. The thickness of the absorbent member 100 is determined in the following way.

[0061] <Absorbent member thickness measurement method> The measurement object (absorbent body 100) is placed on a horizontal surface so that there are no folds or wrinkles, and the thickness of the measurement object is determined under a load of 5 cN/cm ² . Specifically, the thickness is determined, for example, using a thickness gauge, PEACOCK DIAL UPRIGHT GAUGES R5-C (manufactured by OZAKI MFG. CO. LTD.). When measuring, a round or square plate located in the same plane (acrylic plate having a thickness of about 5 mm) adapted to impart a load of 5 cN/cm ^{2 is} placed between the tip of the thickness gauge and the cut-out object of measurement, and the thickness is measured. The thickness is measured at 10 points and the average value is calculated to obtain the thickness of the object to be measured.

[0062] The following dimensions and the like are preferably set. each part of the cluster of fibers 11 (11A or 11B). The dimensions of each part of the fiber cluster 11 can be determined based on an electron microscope image or the like. during the procedure for determining the external shape of the cluster of fibers 11, described later.

When the base surface 111 has a rectangular planar shape as shown in FIG. 5(a), the length L1 of the short side 111a is preferably 0.3 mm or more, more preferably 0.5 mm or more, and is preferably 10 mm or less, more preferably 6 mm or less.

The length L2 of the long side 111b of the base surface 111 having a rectangular planar shape is preferably 0.3 mm or more, more preferably 2 mm or more, and is preferably 30 mm or less, more preferably 15 mm or less.

When the base surface 111 has the largest area among the plurality of surfaces of the fiber cluster 11, as shown in FIG. 5, the length L2 of the long side 111b is equal to the maximum size of the fiber cluster 11, and the maximum size is equal to the diameter of the base surface 111, having a circular planar shape, of the disk-shaped fiber cluster 11B.

The ratio of the length L1 of the short side 111a to the length L2 of the long side 111b, L1/L2, is preferably 0.003 or more, more preferably 0.025 or more, and is preferably 1 or less, more preferably 0.5 or less. In the present invention, the flat shape of the base surface 111 is not limited to such a rectangular shape as shown in FIG. 5(a), and may have a regular square shape, that is, the ratio of the lengths L1 and L2 of the two sides orthogonal to each other, L1/L2, may be equal to 1.

The thickness T of the fiber cluster 11, i. e. the length T between the two opposite base surfaces 111 is preferably 0.1 mm or more, and more preferably 0.3 mm or more, and is preferably 10 mm or less, and more preferably 6 mm or less.

[0063] In the absorbent element 100, the clusters of fibers 11 are preferably evenly distributed at high density throughout the absorbent element 100, since the sensitivity to external forces should be isotropic whenever possible. From this point of view, for any unit area of 10 square mm of the absorbent member 100 in projections in two directions orthogonal to each other, a plurality of fiber clusters 11 preferably overlap with each other. Symbols 11Z in FIG. 2 and FIG. 3 indicate the overlapping portions of the plurality of fiber clusters 11. In the description of “views in two directions orthogonal to each other”, the thickness direction of the absorbent is generally included (i.e., when the absorbent is viewed from its skin-facing or non-skin-facing surface). surface) and a projection angle in a direction orthogonal to the thickness direction (ie, when the absorbent is viewed from the side).

[0064] FIG. 7(a) is an electron microscope image of an example of a fiber cluster of the present invention; and Fig. 7(b) is a view schematically showing the fiber cluster 11 in an electron microscope image. The plurality of fiber clusters 11 contained in the absorbent member 100 may include, as shown in FIG. 7, a cluster of fibers that has a main body 110 and a raised fiber part 113 containing fibers 11F extending beyond the main body 110 and having a lower fiber density (fewer fibers per unit area) than in the main body 110. The absorbent body 100 may include a cluster of fibers 11 having no protrusion of fibers 113, i. e. a cluster of fibers 11 having only a body 110. The protruding portion of the fibers 113 may include the type of fiber ends on the surface (base surface 111 and frame surface 112) as the fiber cluster 11 described above, and includes, as regards the ends of the fibers, the ends fibers extending outward from the surfaces of the cluster of fibers 11.

[0065] The main body 110 is formed by the above-described two opposite base surfaces 111 and the frame surfaces 112 connecting the base surfaces 111. The main body 110 mainly constitutes the cluster of fibers 11 and forms a certain external shape of the cluster of fibers 11 and various properties of the cluster of fibers 11, such as high flexibility, cushioning properties and compression recovery properties mainly due to the main body 110. At the same time, the protruding part of the fibers 113 mainly contributes to improving the weaving properties between the fiber clusters 11 or between the fiber clusters 11 and the water-absorbing fibers 12F, contained in the absorbent body 100 to directly improve the shape retention properties of the absorbent body 100, and affect uniform dispersibility or the like. fiber clusters 11 in absorbent body 100 to indirectly enhance the benefits provided by body 110.

[0066] The main body 110 has a higher fiber density, or more fibers per unit area, than the protruding portion of the fibers 113. Typically, the main body 110 itself has a uniform fiber density. The proportion of the main part 110 in the total mass of the cluster of fibers 11 is usually at least 40% of the mass. or more, preferably 50% of the mass. or more, more preferably 60% of the mass. or more, and even more preferably 85% of the mass. or more. The main body 110 and the projecting part of the fibers 113 can be distinguished using the following procedure for determining the external forms.

[0067] The procedure for determining the outer shape of the main body 110 of the fiber cluster 11 contained in the absorbent member 100 can be carried out by determining the "boundary" between the main body 110 and the outer part, while specifically noting the difference in fiber density between the fiber cluster 11 and its periphery ( difference in number of fibers per unit area) or difference in fiber type or diameter. The main body 110 has a higher fiber density than the peripheral fiber extensions 113 . In addition, the synthetic fibers (thermoplastic fibers) as constituent fibers of the body 110 generally differ in quality and/or size from the 12F water-absorbing fibers (typically cellulose fibers). Therefore, even when the absorbent body 100 contains a large number of fiber clusters 11 and water-absorbent fibers 12F as a mixture, the boundary can be easily determined by specifically observing the above features. The boundary defined as above is the edge (side) of the base surface 111 or the frame surface 112, and the base surface 111 and the frame surface 112 are determined using a boundary determination procedure. Therefore, the main body 110 can be determined. Such a boundary determination procedure can be carried out by observing the object (absorbent member 100) under an electron microscope, if necessary, from several viewing angles. Specifically, when the fiber cluster 11 contained in the absorbent member 100 is such a fiber cluster 11A or 11B as shown in FIG. 5, while "the total area of the two base surfaces 111 is larger than the total area of the frame surfaces 112", in particular, that the base surface 111 has the largest area of the cluster of fibers 11, the base surface 111 having a large area can be relatively easily determined, and thus the outer shape of the main body 110 can be easily determined.

[0068] The protruding portion of fibers 113 includes constituent fibers 11F of body 110, and constituent fibers extend outward from at least one surface of base surfaces 111 and frame surfaces 112 defining the outer surface of body 110, as shown in FIG. 7(b). Fig. 7(b) is a plan view of the fiber cluster 11 as viewed from the base surface 111 (the surface having the largest area of the plurality of surfaces on the fiber cluster 11), and a large number of fibers 11F extend from the frame surface 112, crossing the base surface 111, with the formation of out-of-bounds parts of the fibers 113.

[0069] The protruding portion of the fibers 113 may be of any shape. The protruding portion of the fibers 113 may be composed of a single fiber 11F may be composed of a plurality of fibers 11F in the form of a protruding bundle of fibers 113S described later. The protruding portion of the fibers 113 includes an end in the length direction of the 11F fiber extending from the body 110, and, in addition to such a fiber end, may include a portion other than the ends in the length direction of the 11F fiber (an intermediate portion in the length direction). In other words, in the fiber cluster 11, the ends in the length direction of the constituent fiber 11F may be in the main portion 110, and the other portion or intermediate portion in the length direction may extend (protrude) outward from the main portion 110 in a loop shape. In such a case, the projecting part of the fibers 113 includes a loop-shaped projecting part of the fiber 11F. In other words, of the fiber protrusions 113, the fiber protrusion having an open end is a fiber end type.

[0070] The main role of the fiber projection 113 is, as described above, to weave the plurality of fiber clusters 11 contained in the absorbent body 100 with each other or to weave the fiber clusters 11 with the water absorbent fibers 12F. Generally, when the fiber projection 113 has a longer length protruding from the main body 110, the fiber projection 113 is thicker, or a single fiber cluster 11 has more fiber projections 113, the substances entwined by the fiber projection 113 are more strongly bonded. , and the weave is unlikely to loosen. Therefore, the intended effects of the present invention are more stable.

[0071] In the case where the fiber cluster 11 is a fiber cluster obtained by cutting the original fibrous sheet material 10bs into certain shapes as shown in FIG. 6, a relatively large number of fiber projections 113 are present in the framework surface 112 formed by the cut surface of the fiber cluster 11, but in the base surface 111, that is, the uncut surface, there are no fiber projections 113, or if there are, the number of fiber projections 113 is smaller than in the carcass surface 112. The reason that the projections of the fibers 113 are localized on the carcass surfaces 112 as cutting surfaces is that the projections of the fibers 113 are formed in the form of "fluffs" when the fibrous sheet material is cut. In other words, the skeleton surface 112 formed by cutting the fibrous material sheet 10bs is completely abraded by cutting means such as a cutter during the cutting process, so fluffs can be formed from the constituent fibers 11F of the sheet 10bs, and the skeleton surface can have fluffs. Depending on the types of fibrous sheet material 10bs, the protruding portions of the fibers 113 can be formed by reducing the spacing between cut lines, reducing the cutting speed, or other improvement, and their length can also be controlled. At the same time, base surfaces 111, as uncut surfaces, are not abraded by such cutting means, and thus fluffs or protrusions of fibers 113 are unlikely to be generated.

[0072] Distances L1a (distances in the first direction, see Fig. 6) and distances L2a (distances in the second direction, see Fig. 6) between cutting lines at the time of cutting the fibrous sheet material 10bs are preferably 0.3 mm or more , more preferably 0.5 mm or more, and preferably 30 mm or less, more preferably 15 mm or less, to promote the formation of projections of the fibers 113 or the like. and to provide clusters of fibers 11 having such a necessary size to exhibit the intended effects, and the like.

выступающую длину от каркасной поверхности 112, чем у выступающей части волокон 113. Выступающий пучок волокон 113S может быть на базовой поверхности 111, но обычно находится на каркасной поверхности 112, как показано на Фиг. 7, и базовая поверхность 111 не имеет никакого выступающего за ее пределы пучка волокон или имеет меньшее количество выступающих пучков волокон, чем на каркасной поверхности 112, даже когда наблюдаются выступающие пучки волокон. Причина этого такая же, как и та, почему выступающие части волокон 113 в основном находятся на каркасной поверхности 112 в качестве поверхности разреза, и как описано выше.[0073] As shown in FIG. 7, the cluster of fibers 11 has, as a protruding portion of the fibers 113, a protruding bundle of fibers 113S projecting beyond the main body 110, more specifically from the frame surface 112, and containing a plurality of fibers 11F. At least one of the protruding portions of the fibers 113 of the fiber cluster 11 may be a protruding fiber bundle 113S. The protruding fiber bundle 113S includes a plurality of fibers 11F gathered together protruding from the carcass surface 112, and is characterized in that it has

projecting length from the carcass surface 112 than the projection of the fibers 113. The projecting fiber bundle 113S may be on the base surface 111, but is usually located on the carcass surface 112, as shown in FIG. 7, and the base surface 111 does not have any protruding fiber bundle or has fewer protruding fiber bundles than the frame surface 112 even when protruding fiber bundles are observed. The reason for this is the same as why the projections of the fibers 113 are mainly on the frame surface 112 as the cutting surface, and as described above.

[0074] When the fiber cluster 11 has such a protruding tuft of fibers 113S, which can be called a large fiber protrusion 113 in length, thickness and size, the interweaving between the fiber clusters 11 or between the fiber clusters 11 and the water-absorbing fibers 12F is further enhanced. As a result, the intended effects of the present invention are more stable due to the presence of the fiber clusters 11. The protruding fiber bundle 113S can be formed by cutting the fibrous sheet material 10bs under the above-described conditions in which fluffs can form (see FIG. 6).

[0075] The length of the protruding fiber bundle 113S extending from the body 110, i. e. the protrusion length from the frame surface 112 (cut surface) is preferably 0.2 mm or more, more preferably 0.5 mm or more, and is preferably 7 mm or less, more preferably 4 mm or less. The continuing length of the protruding 113S fiber bundle can be determined using the procedure for determining the outer shape of the fiber cluster 11 (the boundary determination procedure). Specifically, for example, under a microscope from Keyence Corporation (at 50× magnification), a double-sided adhesive tape, manufactured by 3M, is attached to the surface of a transparent acrylic sample table, and the fiber cluster 11 is placed on it and fixed. According to the procedure for determining the outer shape described above, the outer shape of the fiber cluster 11 is determined, then the length of the protrusion of the 11F fiber extending from the outer shape is measured, and the measured protrusion length is considered as the length of the protruding fiber bundle 113S.

[0076] In the protruding fiber bundle 113S, the plurality of its constituent fibers 11F are preferably bonded by fusion to each other. The fusion bonded portion of the 113S protruding fiber bundle generally has a larger size in a direction orthogonal to the length direction of the 113S protruding fiber bundle (diameter when the fusion bonded portion has a circular cross section) than other portions (non-fused portion) of the 113S protruding fiber bundle. When the protruding fiber bundle 113S has such a fusion-bonded part, which can be called a large diameter part, the protruding fiber bundle 113S itself has a higher strength, and this structure further enhances the interweaving between the fiber clusters 11 or between the fiber clusters 11 and the water-absorbing fibers 12F. interlaced through a protruding bundle of 113S fibers. The protruding fiber bundle 113S having the fusion-bonded portion has the advantage that the protruding fiber bundle 113S itself has higher strength, shape-keeping properties, and the like, not only when the protruding fiber bundle 113S is in a dry state, but also when the protruding fiber bundle 113S the 113S fiber bundle absorbs water to keep it wet. Due to this advantage, an absorbent article including the absorbent member 100 can stably exhibit beneficial effects as a result of the presence of the fiber clusters 11 not only when the absorbent member 100 is in a dry state, but also when the absorbent member 100 absorbs bodily fluids emitted by the wearer, such as like urine and menstrual blood, making it wet. Such a protruding 113S fiber bundle having a fusion bonded portion can be obtained by manufacturing the fiber clusters 11 shown in FIG. 6, i.e. in the process of cutting the fibrous sheet 10bs to obtain fiber clusters 11, using, as the fibrous sheet 10bs, "a fibrous sheet having fused portions of its constituent fibers".

[0077] The constituent fibers 11F of the fiber cluster 11 include thermoplastic fibers. The thermoplastic fibers used as the 11F fibers preferably have lower water absorption (poor water absorption) than water-absorbent fibers, and are particularly preferably non-water-absorbent thermoplastic fibers. The constituent fibers 11F of the fiber cluster 11 may include fibrous components (eg, other synthetic fibers and natural fibers) other than thermoplastic fibers. When the constituent fibers 11F of the fiber cluster 11 include weakly hydrophilic fibers, preferably non-water-absorbent fibers, beneficial effects (effects of improving shape retention properties, flexibility, damping properties, compression recovery properties, anti-curl properties, and the like) due to the presence of the fiber cluster 11 stably appear not only when the absorbent body 100 is in a dry state, but also when the absorbent body 100 absorbs water (body fluids such as urine and menstrual blood), which brings it into a wet state. In the fiber cluster 11, the content of thermoplastic fibers as constituent fibers 11F is preferably 90% by mass. or more, more preferably 100 wt. %, based on the total weight of the fiber cluster 11, i. e. the fiber cluster 11 more preferably includes only thermoplastic fibers. In particular, when the constituent fibers 11F are non-absorbent fibers, the beneficial effects due to the presence of the fiber cluster 11 are even more stably exhibited. Accordingly, in the most preferred embodiment, the constituent fibers 11F of the fiber cluster 11 are non-absorbent thermoplastic fibers.

[0078] In the present description, the term "water absorption" can be easily understood by a person skilled in the art in such a way that, for example, the pulp has water absorption. Similarly, it can also be easily understood that thermoplastic fibers have a lower hydrophilicity than cellulose and do not have water absorption capacity. Meanwhile, with regard to the degree of water absorption of the fibers, the relative difference in the water absorption of the fibers can be compared by the moisture content determined by the method described below, and a more preferable water absorption range can also be determined. Fibers having a higher moisture content have a higher water absorption capacity. The water-absorbing fibers preferably have a moisture content of 6% or more, and more preferably 10% or more. Meanwhile, the thermoplastic fibers preferably have a moisture content of less than 6% and more preferably less than 4%. In a narrow sense, fibers having a moisture content of 6% or more can be defined as water-absorbent fibers, while fibers having a moisture content of less than 6% can be defined as non-water-absorbent fibers.

[0079] <Moisture content measurement method>

The moisture content was determined according to JIS P8203 moisture content test method. In other words, the fiber sample was left in the testing laboratory at 40°C and 80% relative humidity for 24 hours, and then the mass W (g) of the fiber sample before absolute dry processing was determined in the laboratory. Then, the sample was left in an electric dryer (for example, manufactured by Isuzu Seisakusho, Co., Ltd.) at 105±2° C. for 1 hour to completely dry the fiber sample. After absolute dry processing in a testing laboratory under standard conditions at a temperature of 20±2°C and a relative humidity of 65±2%, a fiber sample wrapped with Saran Wrap (registered trademark), manufactured by Asahi Kasei Corporation, is placed in a glass desiccator (for example, manufactured by Tech -Jam) containing silica gel (for example, Toyotakako Co., Ltd.) and left until the temperature of the fiber sample reaches 20±2°C. Then, the constant mass W'(g) of the fiber sample is determined, and the moisture content of the fiber sample is calculated according to the following equation. Moisture content (%) = (W - W'/W') × 100.

[0080] In terms of being able to provide excellent effects of the absorbent body 100 equally in terms of shape retention properties, flexibility, cushioning properties, compression recovery properties, anti-curl properties, and the like, both in dry state and in wet state, the fiber cluster 11 preferably has a three-dimensional structure in which a plurality of thermoplastic fibers are fused to each other.

[0081] In order to obtain such a fiber cluster 11 in which a plurality of fusion bonded parts are spatially dispersed, the synthetic fibers as non-absorbent fibers used as the constituent fibers 11F of the fiber clusters 11 preferably include a plurality of thermoplastic fibers, and more preferably only include thermoplastic fibers. As described above, the protruding fiber bundle 113S preferably has a fusion bonded portion. When the constituent fibers 11F of the fiber clusters 11 are thermoplastic fibers, the protruding fiber bundle 113S may have such a preferred structure.

[0082] In order to obtain a fiber cluster 11 in which a plurality of fusion-bonded parts are spatially dispersed, the fibrous sheet material 10bs (see FIG. 6) may have a similar structure. Such a fibrous sheet material 10bs, in which a plurality of fusion bonded parts are spatially dispersed, can be obtained by subjecting a web or nonwoven material mainly containing thermoplastic fibers to a heat treatment such as hot air treatment as described above.

[0083] Examples of the thermoplastic resin as the water-repellent synthetic resin preferred as the material for the constituting fibers 11F of the fiber cluster 11 include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; and polyacrylic acid, polyalkyl methacrylate, polyvinyl chloride and polyvinylidene chloride, and these resins can be used alone or in combination of two or more of them. The 11F fiber may be a monofilament of a single thermoplastic resin or a mixed polymer blend of two or more synthetic resins including thermoplastic resins, or may be a bicomponent fiber. In the description, the bicomponent fiber is a synthetic fiber (thermoplastic fiber) obtained by conjugating two or more synthetic resins containing various components in a spinning machine and simultaneously spinning synthetic resin fibers, and has a structure in which a plurality of components extend in the length direction from corresponding fibers and bind to each other into one fiber. The bicomponent fiber structure includes a core-sheath structure, a back-to-back structure, and the like. and is not specifically limited.

[0084] The fiber cluster 11 preferably has a water contact angle of less than 90 degrees, and more preferably less than 70 degrees, as determined by the following method, in terms of further improving the ability to draw body fluid upon initial release. Such fibers can be obtained by treating the above-described non-water-absorbent synthetic fibers, preferably non-water-absorbent thermoplastic fibers, with a hydrophilizing agent using a conventional procedure. As the hydrophilizing agent, a conventional surfactant can be used.

[0085] <Contact Angle Measurement Method>

From the measurement object (absorbent core), a fiber is selected from a cluster of fibers and the angle of contact of water with the fiber is measured. As the measuring device, an MCA-J automatic contact angle meter manufactured by Kyowa Interface Science Co., Ltd. is used. Deionized water is used to measure the contact angle. The amount of liquid ejected from the water jet sprayer (manufactured by Cluster Technology Co., Ltd., CTC-25 pulse injector having a sprayer pore size of 25 μm) is 20 picoliters, and a drop of water falls directly over the fiber. The dripping state is recorded using a high-speed video recorder connected to a camera installed horizontally. The video recorder is preferably a personal computer integrated with a high speed capture device in terms of subsequent image analysis. When measuring, images are recorded every 17 ms. Of the registered images, the first image in which the water drop reaches the fiber is subjected to image analysis using the supplied FAMAS software (software version: 2.6.2, analytical technique: drop, analytical method: Ɵ/2, image processing algorithm: non-reflective, image processing mode: frame, threshold level: 200, no curvature correction) to calculate the angle between the surface of the water droplet in contact with air and the fiber, which gives the contact angle. A fiber sample from the measurement object is cut into a fiber of 1 mm length, and the cut fiber is placed on the sample table of the contact angle meter and held horizontally. For one fiber, contact angles are measured at two different locations. The contact angles of the five fibers are measured to one decimal place, and the average of the measured values at 10 points in total (rounded to the second decimal place) is determined as the contact angle of water with the fibers. The measurement conditions are room temperature 22±2°C and humidity 65±2% RH.

[0086] As the water-absorbent fibers 12F, water-absorbent fibers commonly used as a material constituting an absorbent in this type of absorbent article can be used. Examples of water absorbent fibers include natural fibers such as wood pulp, including softwood pulp and hardwood pulp, and non-wood pulp, including cotton pulp and hemp pulp; and modified celluloses such as cationized cellulose and mercerized cellulose, and may be used alone or as a mixture of two or more of them. Of the water-absorbent fibers, water-absorbent cellulose fibers are particularly preferred.

[0087] In the absorbent body 100, the weight ratio of the content between the fiber clusters 11 and the water-absorbent fibers 12F is not particularly limited, and can be appropriately adjusted depending on the specific applications of the absorbent body 100, the types of constituent 11F fibers in the fiber clusters 11, and the water-absorbent fibers 12F etc. For example, when the constituent fibers 11F in the fiber clusters 11 are thermoplastic fibers (non-water-absorbent fibers), the water-absorbent fibers 12F are cellulose fibers (water-absorbent fibers), and the absorbent member 100 is included in an absorbent article such as sanitary napkins and disposable diapers, conventionally, the weight ratio between fiber clusters 11 and water-absorbent fibers 12F, first (fiber clusters 11)/last (water-absorbent fibers 12F), preferably 20/80 to 80/20, and more preferably 40/60 up to 60/40, in terms of more likely to achieve the expected effects of the present invention.

[0088] In the absorbent element 100, the content of fiber clusters 11 is preferably 20 wt%. or more, more preferably 40% of the mass. or more, and is preferably 80% of the mass. or less, more preferably 60% of the mass. or less, based on the total weight of the dry absorbent body 100.

In the absorbent element 100, the content of water-absorbing fibers 12F is preferably 20 wt%. or more, more preferably 40% of the mass. or more, and is preferably 80% of the mass. or less, more preferably 60% of the mass. or less, based on the total weight of the dry absorbent body 100.

[0089] In the absorbent body 100, the basis weight of the fiber clusters 11 is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and is preferably 640 g/m ² or less, more preferably 480 g/m ² or less.

In the absorbent body 100, the basis weight of the water-absorbing fibers 12F is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and is preferably 640 g/m ² or less, more preferably 480 g/m ² or less. .

[0090] The absorbent member 100 may include additional components other than fiber clusters 11 and water-absorbent fibers 12F, and examples of the additional component include a water-absorbent polymer. As the water-absorbent polymer, a particulate polymer and a fibrous polymer are commonly used. In use, the high water absorbent particulate polymer may be any shape from a spherical shape, a block shape, an ellipsoid shape, and an indeterminate shape. The water-absorbent polymer preferably has an average particle size of 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, a polymer or copolymer of acrylic acid or alkali metal acrylate can generally be used. Examples thereof include polyacrylic acid, its salts, polymethacrylic acid and its salts.

[0091] In the absorbent element 100, the content of the water-absorbing polymer is preferably 5% by weight. or more, more preferably 10% of the mass. or more, and is preferably 60% of the mass. or less, more preferably 40% of the mass. or less, based on the total weight of the dry absorbent body 100.

In the absorbent body 100, the basis weight of the water-absorbing polymer is preferably 10 g/m ² or more, more preferably 30 g/m ² or more, and is preferably 100 g/m ² or less, more preferably 70 g/m ² or less.

[0092] The basis weight of the absorbent body 100 may be appropriately adjusted depending on its intended applications or the like. For example, when the absorbent 100 is intended to be used as the absorbent of an absorbent article such as disposable diapers and sanitary napkins, the basis weight of the absorbent 100 is preferably 100 g/m ² or more, more preferably 200 g/m ² or more, and is preferably 800 g/m ² or less, more preferably 600 g/m ² or less.

[0093] The absorbent body 100 having the structure as described above has flexibility, excellent damping properties and excellent compression recovery properties, deforms in response to external forces with high sensitivity, and returns to its original state immediately after the external forces are released. Such properties of an absorbent member can be assessed by compressive working load (WC) and restorative working load (WC') as indicators. The compressive workload is an indicator of the shock absorbing properties of an absorbent, and an absorbent having a higher WC value is rated as having a higher shock absorbing property. Recovery workload is a measure indicating the degree of recovery when a compressed absorbent is released from a compressed state, and an absorbent having a higher WC' value is judged to have higher compression recovery properties and is unlikely to curl. Considering that the absorbent element 100 functions to absorb and retain liquid, the absorbent element 100 itself, or an absorbent article including the absorbent element 100, preferably has a higher WC value and a higher WC' value, not only when the absorbent element is in a dry state, but also when the absorbent body absorbs body fluids or the like to make it wet. In order for the wet absorbent body 100 to have such properties, it is effective to use non-absorbent fibers such as thermoplastic fibers as the constituent fibers 11F in the fiber clusters 11 as described above.

[0094] The compressive working load (d-WC) of the absorbent article including the absorbent body 100 in the dry state is preferably 80 mN cm/cm ² or more, more preferably 90 mN cm/cm ² or more, and is preferably 150 mN·cm/cm ² or less, more preferably 110 mN·cm/cm ² or less.

The compressive working load (w-WC) of the absorbent article including the absorbent body 100 when wet is preferably 70 mN cm/cm ² or more, more preferably 80 mN cm/cm ² or more, and is preferably 150 mN cm /cm ² or less, more preferably 110 mN·cm/cm ² or less.

[0095] The restorative working load (d-WC') of the absorbent article including the absorbent body 100 in the dry state is preferably 34 mN cm/cm ² or more, more preferably 44 mN cm/cm ² or more, and is preferably 150 mN·cm/cm ² or less, more preferably 60 mN·cm/cm ² or less.

The restorative working load (w-WC') of the absorbent article including the absorbent body 100 in the wet state is preferably 15 mN·cm/cm ² or more, more preferably 25 mN·cm/cm ² or more, and is preferably 150 mN· cm/cm ² or less, more preferably 55 mN·cm/cm ² or less.

[0096] <Method for measuring compression workload (WC) and recovery workload (WC')>

It is well known that the compressive working load (WC) and recovery working load (WC') of an absorbent article including the absorbent body 100 can be represented by a value measured using the Kawabata Evaluation System (KES), manufactured by Kato Tech Co., Ltd. (background document: The Standardization and Analysis of Texture Evaluation (2nd Edition), author: Sueo Kawabata, July 10, 1980). Specifically, the KES-G5 automatic compression tester manufactured by Kato Tech Co., Ltd. can be used to determine the compression workload and the recovery workload. The measurement procedure is described below.

An “absorbent article including an absorbent member” is attached to the test stand of a compression tester as a sample. Next, the sample is pressed between steel plates, each of which has a round flat surface with an area of 2 cm ² . The compression speed is set at 0.02 cm/sec and the maximum compression load is set at 490 mN/cm ² . During the recovery process, the measurement is carried out at the same speed. Compression workload (WC) and recovery workload (WC') are represented by the following equations. Recovery workload (WC') is the energy when the compressed sample returns to its original state. In the equations, T _m and T _o represent the thickness at a load of 490 mN/cm ² (4.9 kPa) and the thickness at a load of 4.9 mN/cm ² (49 Pa), respectively. In the equations, P _a is the load (mN/cm ² ) during the measurement (compression process), and P _b is the load (mN/cm ² ) during the measurement (recovery process).

[0097] [Math Equation 1]

[0098] [Math Equation 2]

[0099] An “absorbent article including an absorbent” as a sample measured in the measurement method can have any structure that an absorbent has, and examples include “an absorbent article including an absorbent and a layer located on top of the skin-facing surface and/or the non-skin-facing surface of the absorbent member” and “an absorbent article comprising only the absorbent member”. Typically, the compressive working load (WC) and recovery working load (WC') of an absorbent article is predominantly dependent on the absorbent member of the absorbent article, and thus the absorbent article is judged as a sample. The WC and WC' values described herein are determined using "an absorbent article comprising an absorbent member and a layer (topsheet) located on top of the skin-facing surface of the absorbent member" as a reference in the measurement method.

[0100] "Absorbent article including absorbent in dry state" as an object for the measurement method is obtained by keeping the absorbent article in a dry state at a temperature of 23°C and a relative humidity of 50% RH for 24 hours. The “absorbent article including the absorbent in the wet state” as the object for the measurement method is obtained according to the following procedure: the absorbent article in the dry state is placed with the top layer (skin-facing surface) facing up, and on the top layer form an elliptical inlet (the length of the major axis is 50 mm, the length of the minor axis is 23 mm). 3.0 g of defibrinated horse blood is injected from the inlet, then the product is allowed to stand for 1 minute, and then 3.0 g of defibrinated horse blood is additionally injected. After injection, the condition persists for 1 minute. The defibrinated horse blood injected into the measurement object is defibrinated horse blood manufactured by Nippon Bio-test Laboratories Inc. and brought to a viscosity of 8 centipoise at a liquid temperature of 25°C. Viscosity is determined with a TVB-10M viscometer, manufactured by Toki Sangyo Co., Ltd, with an L/Adp rotor (rotor code 19) at a rotation speed of 12 rpm.

[0101] The absorbent of the present invention is preferably used as a constituent element of an absorbent article. In the description, an absorbent article broadly encompasses articles used to absorb body fluids excreted from the human body (such as urine, liquid feces, menstrual blood, and sweat) and encompasses what are referred to as open-type disposable diapers with fastening tapes, sanitary pads, sanitary shorts, incontinence pads, etc. An absorbent in an absorbent article generally includes an absorbent core that absorbs liquid and a liquid-permeable core wrap layer wrapping the outer surface of the absorbent core, and the absorbent of the present invention can be used as the absorbent core. As the core wrapping layer, paper, non-woven material, or the like can be used. The absorbent member 100 may not include any core wrapping layer 10W, in which case the absorbent core 10 is itself used as the absorbent member 100 in the absorbent article.

[0102] An absorbent article comprising an absorbent member of the present invention typically includes a liquid-permeable topsheet that comes into contact with the skin of the wearer of the absorbent article, a liquid-impervious or water-repellent backsheet, and a liquid-retaining absorbent member located between these layers. . As the top layer, various non-woven fabrics, synthetic resin porous sheets and the like can be used, and as the back layer, a synthetic resin film made of polyethylene, polypropylene, polyvinyl chloride, etc. can be used, or can be used, for example, a composite material including a synthetic resin film and a non-woven fabric. The absorbent article may further include various elements depending on the specific applications of the absorbent article. These elements are well known to those skilled in the art. For example, when the absorbent article is intended for use as a disposable diaper or sanitary napkin, a pair or two or more pairs of sealed cuffs may be provided on both sides of the topsheet.

[0103] Next, the manufacturing method of the absorbent member of the present invention will be described based on the manufacturing method of the above absorbent member 100 with reference to the drawings. Fig. 8 shows a schematic configuration of a manufacturing apparatus (fibre laying apparatus) 1 for manufacturing an absorbent member 100. The manufacturing apparatus 1 includes a rotating drum 2 having a storage recess 22 on an outer peripheral surface 2f and a chute 3 having a flow path 30 for conveying raw materials of the absorbent member 100 , more specifically, the absorbent core 10, to the outer peripheral surface 2f. While the rotary drum 2 rotates about the rotation axis in the drum circumferential direction 2Y, raw materials conveyed by the air flow (air vacuum) generated in the flow path 30 by aspiration from inside the rotary drum 2 are deposited in the form of fibers on the accumulation recess 22 The first feed mechanism 4 and the second feed mechanism 5 are connected to the chute 3 as feed mechanisms for the raw material (fiber materials) of the absorbent core 10. On the discharge side of the rotary drum 2, a vacuum conveyor 6 is provided, which receives the fiber laying product of the raw materials released from the storage tank. recesses 22, i. e. absorbent core 10 and transports the absorbent core to the next stage. On the rotating drum 2, opposite to the chute 3, a pressure belt 7 is provided on the outer peripheral surface 2f of the rotation drum 2 to press the fiber laying product into the storage cavity 2. The pressure belt 7 is an endless and breathable or non-breathable belt, it connects the roller 71 and the roller 72 and is designed to synchronize them with the rotation of the rotating drum 2

[0104] The rotary drum 2 includes a cylindrical drum main body 20 made of a rigid metal body, and a peripheral member 21 circumferentially surrounding the drum main body 20 and forming an outer peripheral surface 2f of the rotary drum 2. In response to the driving force from the power source, such as a motor, the peripheral member 21 rotates in the direction R1 in the drum circumferential direction 2Y about the horizontal rotation axis as a rotation center, while the drum main body 20 provided inside the peripheral member 21 is stationary and does not rotate. Each edge of the drum main body 20 in the drum width direction is sealed with a sealing material such as a side wall and felt (not shown).

[0105] The peripheral member 21 includes a breathable porous plate 23 forming a bottom of the storage recess 22 or a surface for depositing fibers of raw materials, and a non-breathable plate 24 forming a surface other than a fiber depositing surface on the outer peripheral surface 2f of the rotating drum 2. The production apparatus 1 includes a pair of pattern forming plates 24 each having an annular shape continuously extending along its entire length in the circumferential direction 2Y of the drum, and which are provided at both ends in the rotation axis direction of the rotating drum 2, and between the pair forming the pattern of the plates 24, 24 is a porous plate 23.

[0106] The porous plate 23 is an air-permeable plate that allows the air flow generated by aspiration to pass from the inside of the device (inside the rotating drum 2) to the outside of the device (outside the rotating drum 2), prevents the passage of raw materials conveyed through airflow, but retains the starting materials and allows only air to pass through. The porous plate 23 has a plurality of aspiration holes penetrating the plate in the thickness direction through the porous plate 23, and the aspiration holes function as airflow transfer holes when the accumulation recess 22 moves in a space in which a negative pressure is maintained in the rotating drum 2. B as the porous plate 23, for example, a metal or resin mesh plate or a metal or resin plate having a large number of small holes formed by etching or stamping can be used. As the pattern plate 24, for example, a metal plate such as stainless steel and aluminum or a resin plate can be used.

[0107] As shown in FIG. 8, the inside of the drum main body 20 is divided in the drum circumferential direction 2Y into a plurality of zones A, B, and C. A vacuum mechanism (not shown) is connected to the drum main body 20 to reduce pressure therein. The vacuum mechanism includes an exhaust pipe (not shown) connected to a side wall (not shown) of the drum main body 20 and an exhaust fan (not shown) connected to the exhaust pipe. The plurality of zones A, B, and C in the drum main body 20 are independent of each other, and the vacuum mechanism can independently control the negative pressures (absorption powers) of these zones.

[0108] In the rotating drum 2, the predetermined range in the drum circumferential direction 2Y, in particular, the area A having the periphery covered by the chute 3 is a fiber placement area capable of stacking raw material fibers by aspiration from the inside. When the peripheral member 21 is rotated around the rotation axis while the area A is maintained at a negative pressure, the negative pressure in the area A is applied to the bottom (porous plate 23) of the storage recess 22, while the storage recess 22 formed on the peripheral member 21 moves in zone A, and air is aspirated through a large number of aspiration holes formed on the bottom. By aspiration through the aspiration holes, the raw materials conveyed through the supply path 32 in the chute 3 are introduced into the storage cavity 22, and the fibers are deposited at its bottom. Meanwhile, zone B in the rotary drum 2 is generally set at a lower negative pressure than zone A, or at a pressure of 0 (atmospheric pressure), and zone C is an area including the transfer position of the fiber laying product into the storage cavity 22 and into forward and backward from it and thus set to 0 pressure or positive pressure.

[0109] The vacuum conveyor 6 includes an endless breathable belt 63 connecting the driving roller 61 and the driven rollers 62, and a vacuum box 64 provided at a position facing space C in the rotating drum 2 across the breathable belt 63. A layer of 10W is placed on the breathable belt 63 for core wrapping, and the core wrapping layer 10W is for receiving the absorbent core 10, which is the fiber stacking product released from the accumulating recess 22.

[0110] As shown in FIG. 8, the chute 3 continuously extends from the first feeder 4 along the rotary drum 2 and has an opening on the inlet side in the feed direction of raw materials, an opening on the outlet side (rotary drum 2 side), and a raw material flow path 30 between the holes. On the surface of the trough 3, there is a resin spray tube 31 for supplying water-absorbent resin particles to the flow path 30, and the resin spray tube 31 is used when the absorbent core 10 contains water-absorbent resin particles.

[0111] As described above, the absorbent core 10 contains two types of fibrous materials, including clusters of fibers 11 and water-absorbent fibers 12F. The production apparatus 1 solves this problem and includes, as fibrous material feeders, a first feeder 4 for feeding 12F water-absorbent fibers into the chute 3 (device for producing water-absorbing fibers) and a second feeder 5 for feeding fiber clusters 11 into the chute 3 (device for obtaining fiber clusters).

[0112] The first feed mechanism 4 is provided in the opening of the chute 3 opposite the side of the rotary drum 2. The first feed mechanism 4 has a similar structure to the fibrous material feed mechanism of this type of fiber stacker for cellulose fibers or the like, and includes a defibrating device 41 for defibration of the continuous sheet fibrous material 10a in which a plurality of water-absorbent fibers 12F are accumulated.

[0113] In FIG. 9 schematically shows an enlarged second feed mechanism 5. The second feed mechanism 5 is a device for carrying out a cutting step for cutting a continuous sheet of fibrous material 10b containing constituent fibers 11F of fiber clusters 11 in two directions intersecting each other (the first direction D1 and the second direction D2) to a predetermined length as shown in FIG. 6, and includes a first cutting roller 53 for cutting an object to be cut (fiber sheet 10bs) in the first direction D1, a second cutting roller 54 for cutting an object to be cut in the second direction D2, and one take-up roller 55 provided between the rollers 53 and 54. These three rollers 53, 54 and 55 rotate in opposite directions while the respective rotation axes are parallel and the respective outer peripheral surfaces face each other. The cutting rollers 53 and 54 have cutting blades 51 and 52 on the outer peripheral surfaces, while the take-up roller 55 has no cutting blades on the outer peripheral surface and has a smooth surface. Near the outer peripheral surface of the take-up roller 55, the guide roller 56, the first cutting roller 53, the guide roller 57, and the second cutting roller 54 are arranged in series from the input side in the direction of rotation.

[0114] The “first direction D1” as one of the cutting directions of the fibrous material sheet 10b corresponds to the movement direction MD of the fibrous material sheet 10bs in the second feed mechanism 5, and the angle between the first direction D1 and the movement direction MD is less than 45 degrees. In the embodiment shown in the drawings, the first direction D1 is the same as the movement direction MD, and the angle between the directions D1 and MD is 0.

“Second direction D2” as another cutting direction of the fiber sheet 10bs intersects the first direction D1. In the embodiment shown in the drawings, the first direction D1 (moving direction MD) is orthogonal to the second direction D2, and the angle between the directions D1 and D2 is 90 degrees.

The direction indicated as CD in FIG. 8, orthogonal to the direction of movement MD and parallel to the axes of rotation of the rotating drum 2 and the various rollers included in the manufacturing apparatus 1. In the embodiment shown in the drawings, this direction coincides with the width directions (the direction orthogonal to the longitudinal direction) of the absorbent core 10 as the lay product. long continuous fibers and long continuous sheets of fibrous material 10as and 10bs.

[0115] As shown in FIG. 8 and FIG. 9, the first cutting roller 53 has, on its outer peripheral surface, a plurality of cutting blades 51 that extend in the circumferential direction of the roller 53 (first direction D1) at predetermined intervals in the direction of the rotation axis of the roller 53, namely the direction CD (second direction D2).

The second cutting roller 54 has on the outer peripheral surface a plurality of cutting blades 52 that extend in the direction of the rotation axis of the roller 54, namely in the direction CD (second direction D2), at predetermined intervals in the circumferential direction of the roller 54, or in the direction of movement MD (first direction D1).

[0116] The production method of the absorbent body 100 using the production apparatus 1 having the structure as described above is basically the same as the conventional production method using the fiber placing apparatus having the same structure. In other words, as shown in FIG. 8, while the rotary drum 2 rotates about the rotation axis in the direction R1 along the circumference 2Y of the drum, the water-absorbing fibers 12F obtained by defibration of the fiber sheet 10a in the first feed mechanism 4 are conveyed by the air flow (air vacuum) generated on the the flow path 30 of the trough 3 by aspiration from inside the rotating drum 2 into the rotating drum 2, and it is possible to deposit the fibers on the storage recess 22 in the region of zone A, to obtain a fiber deposit product. The fiber stacking product is an absorbent core 10. The absorbent core 10 in the storage recess 22 passes through the region in the zone A (the region closed from above by the groove 3 on the outer peripheral surface 2f of the rotating drum 2) as the peripheral member 21 rotates, then is pressed by the pressure band 7 , when it enters the area in zone B, and moves close to the vacuum conveyor 6. Then, the absorbent core is released from the storage recess 22, and then transferred to the 10W core wrap layer introduced by the vacuum conveyor 6, and is wrapped with the 10W core wrap layer.

[0117] The method for producing the absorbent body 100 is characterized in that, in addition to the above main steps, it includes the steps of manufacturing and feeding the fiber clusters 11 by the second feeder 5. In other words, the method for manufacturing the absorbent body 100 is mainly characterized in that it includes the step of cutting and a mixing step as shown in FIG. 8 and FIG. 9. In the cutting step, the continuous fiber sheet 10b in which a plurality of fibers 11F are accumulated is cut in the first direction D1 (moving direction Y) along the longitudinal direction of the fibrous sheet 10b to obtain a plurality of continuous thin pieces of the sheet 10bt, and then a plurality of thin pieces the sheet 10bt is cut in a second direction D2 (direction CD) intersecting (in the embodiment shown in the drawings "orthogonal") with the first direction D1 to obtain fiber clusters 11. fibers 12F.

[0118] In the second feed mechanism 5, the continuous sheet fibrous material 10bs is first cut between the first cutting roller 53 and the take-up roller 55 in the first direction D1, which is the longitudinal direction of the sheet 10bs and is the direction of movement Y, to obtain a plurality of thin pieces of the sheet 10bt extending in direction D1. Then, between the take-up roller 55 and the second cutting roller 54, these continuous thin pieces of the sheet 10bt are cut in the second direction D2, which is the width direction (CD direction) orthogonal to the longitudinal direction (cutting stage). By sequentially cutting thus the continuous fibrous material sheet 10bs in the first direction D1 and in the second direction D2 orthogonal to the first one, the fibrous material sheet 10b is cut into squares as shown in FIG. 110 of the plurality of fiber clusters 11 obtained as described above is a cuboid shape as shown in FIG. 5(a).

[0119] A plurality of fiber clusters 11 obtained by cutting the fibrous sheet material 10b are fed through the aspiration nozzle 58 to the flow path 30 in the chute 3, then mixed with the water-absorbing fibers 12F dispersed in the flow path 30 from the first feed mechanism 4 in the direction of the rotating drum 2, and the fibers are stacked together with the water-absorbing fibers 12F on the storage recess 22 (mixing stage). The suction nozzle 58 has holes at both ends in its longitudinal direction. One hole 581 is located near the closest point between the second cutting roller 54 and the take-up roller 55, and the other hole (not shown) communicates with the flow path 30 in the chute 3. A plurality of fiber clusters 11 formed between the second cutting roller 54 and the take-up roller 55, are caught through the opening 581 into the aspiration nozzle 58 and fed into the chute 3. In the production device 1, the connection position between the aspiration nozzle 58 and the chute 3 is between the rotating drum 2 and the first feed mechanism 4, as shown in FIG. 8 and is closer to the rotating drum 2 than the resin spray tube 31.

[0120] The present invention has been described based on the embodiments, but the present invention can be modified accordingly without being limited to the embodiments.

For example, in the absorbent element of the present invention, the fiber clusters are not necessarily evenly distributed throughout the absorbent element and may be localized. As an embodiment in which fiber clusters are localized, an exemplary absorbent member has a multilayer structure including a layer primarily containing fiber clusters and a layer primarily containing water-absorbent fibers.

In the absorbent body of the present invention, all fiber clusters (synthetic fiber aggregates) contained are not necessarily defined fiber aggregates such as fiber clusters 11, and a very small amount of undefined fiber aggregates may be contained in addition to the defined fiber aggregates, without departing from the scope and essence of the present invention. In view of the above embodiments of the present invention, the following aspects are further disclosed.

[0121] <1> Absorbent element, including:

fiber clusters containing thermoplastic fibers; and

water absorbent fibers

the absorbent element includes, in the direction of the plane of the absorbent element, a first zone in which a plurality of fiber clusters are fused to each other, and a second zone in which a plurality of fiber clusters are not fused, but intertwined with each other,

in at least the second zone, the fiber clusters are intertwined with water-absorbing fibers, and

the fiber clusters include a body formed by two opposite base surfaces and a frame surface intersecting the base surfaces.

<2> The absorbent member of <1>, wherein the base surfaces are rectangular in planar form, and the short side of the rectangular shape is equal to or shorter than the thickness of the absorbent member.

<3> The absorbent member of <2>, wherein the ratio of the length of the short side of the base surface to the thickness of the absorbent member, first/last, is 0.03 or more and 1 or less, and preferably 0.08 or more and 0.5 or less.

<4> The absorbent body according to <2> or <3>, wherein the short side of the base surface has a length of 0.3 mm or more and 10 mm or less, and preferably 0.5 mm or more and 6 mm or less.

<5> The absorbent body according to any one of <2> to <4>, wherein the long side of the base surface has a length of 0.3 mm or more and 30 mm or less, and preferably 2 mm or more and 15 mm or less.

[0122] <6> The absorbent member according to any one of <1> to <5>, wherein, at any unit area of 10 square mm, an overlapping portion of a plurality of fiber clusters is observed in two direction orthogonal projections of the absorbent member.

<7> The absorbent member according to any one of <1> to <6>, wherein the constituent fibers of the fiber cluster are non-absorbent fibers.

<8> The absorbent body according to any one of <1> to <7>, wherein the fiber cluster has a three-dimensional structure in which a plurality of thermoplastic fibers are bonded to each other by fusion.

<9> The absorbent member according to any one of <1> to <8>, wherein the first zones and the second zones are alternately disposed in the plane direction of the absorbent member.

[0123] <10> The absorbent member according to any one of <1> to <9>, wherein the absorbent member has a longitudinal direction and a transverse direction orthogonal thereto, the first zone is located on the inside of the side edge along the longitudinal direction of the absorbent element, and the second zone is located outside the first zone in the transverse direction.

<11> The absorbent member of <10>, wherein the distance between the first region and the side edge along the longitudinal direction is 1 mm or more, preferably 5 mm or more, and more preferably 8 mm or more, and is 30 mm or less, preferably 25 mm or less, and more preferably 20 mm or less.

<12> The absorbent member according to any one of <1> to <11>, wherein the absorbent member has a longitudinal direction and a transverse direction orthogonal thereto, and the first zone is located in a central portion in the longitudinal direction of the absorbent member.

<13> The absorbent member according to any one of <1> to <12>, wherein the absorbent member has a longitudinal direction and a transverse direction orthogonal thereto, and the first two zones are spaced apart in the transverse direction of the absorbent member and extend in the longitudinal direction.

<14> The absorbent member of <13>, wherein the distance between the first zones adjacent in the transverse direction of the absorbent member is 5 mm or more, preferably 8 mm or more, and more preferably 10 mm or more, and is 60 mm or less, preferably 50 mm or less, and even more preferably 45 mm or less.

<15> The absorbent member according to any one of <1> to <12>, wherein the plurality of first zones are circular in planar form and are scattered in the plane direction of the absorbent member.

<16> The absorbent member according to any one of <1> to <12>, wherein the absorbent member has a longitudinal direction and a transverse direction orthogonal thereto, and a single first zone is provided in the central portion of the absorbent member in the longitudinal direction and the transverse direction.

<17> The absorbent body according to any of <1> to <12>, wherein the plurality of first zones are linear in shape and intersect with each other to form a grid-like pattern on the absorbent body.

<18> The absorbent according to any one of <1> to <9>, wherein the absorbent has a longitudinal direction and a transverse direction orthogonal thereto, and a plurality of first zones are distributed in side edge portions along the longitudinal direction of the absorbent and extend in a direction that intersects with a longitudinal direction and a transverse direction of the absorbent element.

[0124] <19> The absorbent member according to any one of <1> to <18>, wherein the total area of the two base surfaces is greater than the total area of the frame surface.

<20> The absorbent body according to any one of <1> to <19>, wherein the fiber cluster has a protruding fiber bundle protruding outward from the carcass surface and containing a plurality of fibers.

<21> The absorbent member of <20>, wherein the protruding fiber bundle has a portion in which a plurality of fibers are bonded to each other by fusion.

<22> The absorbent body according to <20> or <21>, wherein the fiber cluster has a main body formed by the base surfaces and the carcass surface, and an increasing length of the protruding fiber bundle from the main body, i.e. the increasing length from the frame surface is preferably 0.2 mm or more and 7 mm or less, and more preferably 0.5 mm or more and 4 mm or less.

<23> The absorbent member according to any one of <1> to <22>, wherein the outer shape of the fiber cluster is a cuboid shape or a disc shape.

<24> The absorbent member according to any one of <1> to <23>, wherein the ratio, by weight, of fiber clusters to water absorbent fibers, first/last, is 20/80 to 80/20.

<25> The absorbent member according to any one of <1> to <24>, wherein in the absorbent member, the fiber clusters are intertwined with each other or with the water-absorbent fibers and are capable of interweaving with each other or with the water-absorbent fibers.

<26> The absorbent member according to any one of <1> to <25>, wherein 70% or more, and preferably 80% or more, of the fiber clusters having an associated portion with each other or with the water-absorbent fibers are bonded by fiber interlacing.

<27> The absorbent member according to any one of <1> to <26>, wherein the fiber clusters are obtained from a nonwoven fabric.

<28> The absorbent member according to any one of <1> to <27>, wherein the ratio of the number of fiber ends per unit area on the base surface, N ₁ , to the number of fiber ends per unit area on the carcass surface, N ₂ , N ₁ /N ₂ is 0 or more and 0.90 or less, and preferably 0.05 or more and 0.60 or less.

<29> The absorbent element according to any one of <1> - <28>, wherein the number of fiber ends per unit area on the base surface is 0 end portions of the fibers / mm ² or more and 8, the end portions of the fibers / mm ² or less, and preferably 3, the end portions of the fibers / mm ² or more and 6, the end portions of the fibers / mm ² or less.

<30> The absorbent element according to any one of <1> - <29>, wherein the number of fiber ends per unit area on the carcass surface of 5 the end portions of the fibers / mm ² or more and 50 the end portions of the fibers / mm ² or less, and preferably 8 parts of the ends of the fibers / mm ² or more and 40 the end portions of the fibers / mm ² or less.

[0125] <31> An absorbent article including an absorbent according to any one of <1> to <30>.

<32> The absorbent article of <31>, wherein the absorbent article in the dry state has a compressive working load (d-WC) of preferably 80 mN cm/cm ² or more and 150 mN cm/cm ² or less, and more preferably 90 mN·cm/cm ² or more; and 110 mN·cm/cm ² or less.

<33> The absorbent article according to <31> or <32>, wherein the absorbent article in the dry state has a restorative working load (d-WC') of preferably 34 mN cm/cm ² or more and 150 mN cm/cm ² or less, and more preferably 44 mN·cm/cm ² or more and 60 mN·cm/cm ² or less.

Examples

[0126] The present invention will now be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0127] [Examples 1-3]

An absorbent body producing apparatus having the same structure as the manufacturing apparatus 1 shown in FIG. 8 was used to produce an absorbent member including an absorbent core and a core wrapping layer according to the production method described above. On one side of the absorbent element (the front side, which should face the skin when the absorbent element is included in the absorbent article), a predetermined pattern is partially hot-embossed in the usual way with the formation of first zones, obtaining an absorbent element having first zones (parts with embossed pattern) and second zones (parts without relief pattern). A breathable nonwoven fabric having a basis weight of 30 g/m ² was used as the top layer, a polyethylene resin film (FL-KDJ100nN, manufactured by Daika Kogyo Co., Ltd.) having a basis weight of 37 g/m ² was used as backsheet, and the absorbent was placed between the topsheet and the backsheet, obtaining a sanitary napkin as samples of Examples 1-3. The configuration of the first zones was any configuration shown in FIG. 1(a) and FIG. 4.

As for the fibrous sheet of fiber clusters, a breathable nonwoven fabric (a fibrous sheet having parts of its constituent fibers bonded by fusion) having a basis weight of 18 g/m ² and containing, as constituent fibers, hydrophobic thermoplastic fibers (non-absorbent fibers , fiber diameter 18 µm), which were obtained from polyethylene resin and polyethylene terephthalate resin. As water-absorbing fibers, bleached softwood kraft pulp (NBKP) having a fiber diameter of 22 µm was used. The fiber clusters (certain aggregates of synthetic fibers) used in the absorbent body had a main body having a cuboid shape as shown in FIG. 5(a). The short side 111a of the base surface 111 was 0.8 mm, the long side 111b was 3.9 mm, and the thickness T was 0.6 mm. On the base surface 111, the number of fiber ends per unit area was 3.2 fiber ends/mm ² , and on the frame surface 112, the number of fiber ends per unit area was 19.2 fiber ends/mm ² . As the core wrapping layer, thin paper (soft tissue paper) having a basis weight of 16 g/m ² and a thickness of 0.3 mm was used. The absorbent member had a thickness of 5.7 mm.

[0128] [Comparative Example 1]

A commercially available sanitary napkin (manufactured by Unicharm Corporation, trade name "Tanom Pew Slim 23 cm") was used as Comparative Example 1. The absorbent member in the sanitary napkin of Comparative Example 1 is a mixture of synthetic fibers and cellulose fibers (water absorbent fibers) and does not contain no fiber clusters.

[0129] [Reference Example 1]

The same procedure as in Example 1 was carried out, except that instead of hot stamping the absorbent, the entire absorbent was heated at a temperature of 150°C, at which the polyethylene resin and polyethylene terephthalate resin in the fiber clusters melted, for 600 seconds to obtain an absorbent. , and the absorbent, the topsheet and the backsheet were used to obtain a sanitary napkin as a sample of Reference Example 1.

[0130] [Performance evaluation]

The flexibility, anti-curl properties, and shape retention properties of each sanitary napkin of Examples, Comparative Example, and Reference Example were evaluated. Dry compressive workload (d-WC) was used as an index to evaluate flexibility. Dry recovery workload (d-WC') was used as an index to evaluate anti-curl properties. The following percent deformation was used as an indicator to evaluate the shape retention properties. The results are shown in Table 1.

[0131] <Deformation percentage measurement method>

The percent deformation of the sanitary napkin (absorbent article) was determined using a human body model driven by the lower half of a woman's body. First, the central width of the spacer was determined as the object of evaluation. A parallelepiped-shaped acrylic plate (length about 200 mm, width about 100 mm, thickness about 5 mm) was placed in the center of the pad and 6 g of defibrinated horse blood was injected. The pad was left for 1 minute and attached to the shorts, and the shorts were attached to the female body model. The defibrinated horse blood used in the measurement was the above-described “defibrated horse blood manufactured by Nippon Bio-test Laboratories Inc. with a viscosity adjusted to 8 cP at a fluid temperature of 25°C”. The human body model was then allowed to walk at 100 steps/minute for 30 minutes. After walking, the width of the center of the pad was determined, and the width of the center before walking and the width of the center after walking were used to calculate the percent deformation according to the following equation. A gasket that has a lower percentage of deformation is highly valued.

Warp Percentage = [{(Center Width Before Walking) - (Center Width After Walking)}/(Center Width Before Walking)] × 100

[0132]

Table 1 Example Comparative Example Reference Example one 2 3 one one Presence or absence of fiber clusters Presence Presence Presence Absence Presence Method of bonding between fiber clusters Weave/
fusion bonding Weave/
fusion bonding Weave/
fusion bonding - Fusion Bonding Content of fiber clusters (wt. %) 50 50 50 - 50 Fiber cluster size (mm) 0.8×3.9 0.8×3.9 0.8×3.9 - 0.8×3.9 Base weight of fiber clusters (g/m ² ) 175 175 175 116 ^*1 175 Base weight of water-absorbing fibers (g/m ² ) 175 175 175 116 175 Base weight of water-absorbing polymer (g/m ² ) 50 50 50 35 50 First zone configuration (embossed part) Fig. 1(a) Fig. 4(a) Fig. 4(d) - - Flexibility d-WC
(mN⋅sm / cm ²⁾ 109.96 91.92 92.12 32.34 72.52 anti-curl properties d-WC'
(mN⋅sm / cm ²⁾ 58.14 47.24 48.02 17.64 43.12 Shape save properties Deformation percentage (%) 18.00 21.00 19.00 40.00 25.00 *1: The basis weight of the synthetic fibers contained in the absorbent is shown because the absorbent does not contain any fiber clusters.

[0133] As shown in Table 1, in the sanitary napkins of Examples, each absorbent member contains fiber clusters containing thermoplastic fibers in addition to water-absorbent fibers, and has a first zone (embossed portion) in which a plurality of fiber clusters are fused to each other. , and a second zone in which a plurality of fiber clusters are not fused, but intertwined with each other, in the direction of the plane of the absorbent, and thus the sanitary napkin has excellent flexibility and shape retention properties and is unlikely to curl compared to the pads of the Comparative Example 1 and Reference Example 1 that do not satisfy the conditions described above. Therefore, in order to obtain an absorbent article that includes an absorbent that has excellent shape retention properties, flexibly deforms in response to external forces with high sensitivity, and has excellent wearing comfort and fit properties, an effective result is obtained when the absorbent contains fiber clusters and has a second zone in which a plurality of fiber clusters are not fused, but intertwined with each other.

Industrial Applicability

[0134] The absorbent body of the present invention has excellent shape retention properties, flexibly deforms according to external forces with high sensitivity, and can improve wearing comfort and fit properties when included in an absorbent article.

The absorbent article of the present invention includes such a high-quality absorbent member and thus has excellent wearing comfort properties and fitting properties.

Claims (38)

1. Absorbent element, including: fiber clusters containing thermoplastic fibers; and water absorbent fibers the absorbent element includes, in the direction of the plane of the absorbent element, a first zone in which a plurality of fiber clusters are fused to each other, and a second zone in which a plurality of fiber clusters are not fused, but intertwined with each other, in at least the second zone, the fiber clusters are intertwined with water-absorbing fibers, and the fiber clusters include a body formed by two opposite base surfaces and a frame surface intersecting the base surfaces. 2. Absorbent element according to claim 1, wherein the base surfaces are rectangular in planar form and the short side of the rectangular shape is equal to or shorter than the thickness of the absorbent element. 3. An absorbent according to claim 2, wherein the ratio of the short side length of the base surface to the thickness of the absorbent, first/last, is 0.03 or more and 1 or less. 4. An absorbent member according to claim 2, wherein the short side of the base surface has a length of 0.3 mm or more and 10 mm or less. 5. An absorbent member according to claim 2, wherein the long side of the base surface has a length of 0.3 mm or more and 30 mm or less. 6. Absorbent element according to claim 1, while in any unit area of 10 square mm in the projections of the absorbent element in two directions, orthogonal to each other, an overlapping part of a plurality of fiber clusters is observed. 7. Absorbent body according to claim 1, wherein the constituent fibers of the fiber cluster are non-absorbent fibers. 8. Absorbent element according to claim 1, wherein the cluster of fibers has a three-dimensional structure in which a plurality of thermoplastic fibers are bonded to each other by fusion. 9. Absorbent element according to claim 1, wherein the first zones and the second zones are alternately located in the direction of the plane of the absorbent element. 10. The absorbent element according to claim 1, wherein the absorbent element has a longitudinal direction and a transverse direction orthogonal to it, the first zone is located on the inner side of the side edge along the longitudinal direction of the absorbent element, and the second zone is located outside the first zone in the transverse direction. 11. An absorbent member according to claim 10, wherein the distance between the first zone and the side edge along the longitudinal direction is 1 mm or more and 30 mm or less. 12. Absorbent element according to claim 1, wherein the absorbent element has a longitudinal direction and a transverse direction orthogonal to it, and the first zone is located in the central part in the longitudinal direction of the absorbent element. 13. Absorbent element according to claim 1, wherein the absorbent element has a longitudinal direction and a transverse direction orthogonal to it, and the first two zones are located at a distance from each other in the transverse direction of the absorbent element and extend in the longitudinal direction. 14. An absorbent according to claim 13, wherein the distance between the first zones adjacent in the transverse direction of the absorbent is 5 mm or more and 60 mm or less. 15. Absorbent element according to claim 1, wherein the plurality of first zones are circular in planar form and are scattered in the direction of the plane of the absorbent element. 16. Absorbent element according to claim 1, wherein the absorbent element has a longitudinal direction and a transverse direction orthogonal to it and a single first zone is provided in the central part of the absorbent element in the longitudinal direction and the transverse direction. 17. An absorbent member as claimed in claim 1, wherein the plurality of first zones are linear and intersect with each other to form a grid pattern on the absorbent member. 18. Absorbent element according to claim 1, wherein the absorbent element has a longitudinal direction and a transverse direction orthogonal to it and a plurality of first zones are distributed in parts of the side edge along the longitudinal direction of the absorbent element and extend in a direction that intersects with the longitudinal direction and the transverse direction of the absorbent element . 19. Absorbent element according to claim 1, wherein the total area of the two base surfaces is greater than the total area of the framework surface. 20. An absorbent member as claimed in claim 1, wherein the fiber cluster has a protruding fiber bundle projecting outward from the frame surface and containing a plurality of fibers. 21. An absorbent body according to claim 20, wherein the protruding bundle of fibers has a portion in which a plurality of fibers are bonded to each other by fusion. 22. An absorbent body according to claim 20, wherein the fiber cluster has a body formed by base surfaces and a carcass surface, and increasing the length of the protruding fiber bundle from the body is 0.2 mm or more and 7 mm or less. 23. An absorbent body according to claim 1, wherein the outer shape of the fiber cluster is a cuboid or disc shape. 24. Absorbent element according to claim 1, wherein the ratio, by weight, of fiber clusters to water-absorbing fibers, first/last, is from 20/80 to 80/20. 25. An absorbent element according to claim 1, wherein in the absorbent element the clusters of fibers are intertwined with each other or with the water-absorbing fibers and are capable of interweaving with each other or with the water-absorbing fibers. 26. An absorbent member according to claim 1, wherein 70% or more of the fiber clusters having an associated portion with each other or with the water-absorbing fibers are bonded by weaving the fibers. 27. Absorbent element according to claim 1, wherein the fiber clusters are obtained from a nonwoven material. 28. An absorbent element according to claim 1, wherein the ratio of the number of fiber ends per unit area on the base surface, N ₁ , to the number of fiber ends per unit area on the frame surface, N ₂ , N ₁ /N ₂ , is 0 or more and 0.90 or less. 29. The absorbent item of Claim. 1, the number of fiber ends per unit area on the base surface is 0 end portions of the fibers / mm ² or more and 8, the end portions of the fibers / mm ² or less. 30. The absorbent item of Claim. 1, the number of fiber ends per unit area on the surface of the carcass of 5 the end portions of the fibers / mm ² or more and 50 the end portions of the fibers / mm ² or less. 31. Absorbent article, including the absorbent element according to claim 1. 32. An absorbent article according to claim 31, wherein the absorbent article in the dry state has a compressive working load of 80 mN·cm/cm ² or more and 150 mN·cm/cm ² or less. 33. An absorbent article according to claim 31, wherein the absorbent article in the dry state has a restorative working load of 34 mN·cm/cm ² or more and 150 mN·cm/cm ² or less.

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