RU2763679C2 - Absorbent and absorbent product - Google Patents

Abstract

FIELD: absorbent products.

SUBSTANCE: absorbent element and absorbent product can be used in various branches of industry, e.g., as an absorbent pad. The absorbent element and absorbent product, according to the present invention, comprise: multiple fibrous clusters containing synthetic fibres and multiple absorbent fibres. The fibrous clusters are mixed with each other or the fibrous clusters and absorbent fibres are mixed. Each of the fibrous clusters comprises two opposite base surfaces and a body surface connecting the two base surfaces. The amount of end parts of fibres per unit area of the body surface is greater than the amount of end parts of fibres per unit area of each of the base surfaces.

EFFECT: increase in the flexibility and absorbing capacity of the adsorbing element and adsorbing products.

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Description

Scope of technical application

The present invention relates to an absorbent element for use in an absorbent article.

Prerequisites for the invention

An absorbent article, such as a disposable diaper or sanitary napkin, typically consists of: a topsheet laid so as to be positioned relatively close to the wearer's skin; a back sheet laid so as to be positioned relatively far from the user's skin; and an absorbent member positioned between the top sheet and the back sheet. Typically, the absorbent body is formed mainly from hydrophilic fibers (absorbent fibers), for example, wood pulp; and often also contains absorbent polymeric particles. The main problems of an absorbent for use in an absorbent article are in terms of improving various properties such as flexibility, resilience, and shape retention.

An absorbent body improvement technology is disclosed in, for example, Patent Document 1. Patent Document 1 discloses an absorbent body comprising thermoplastic polymer fibers and cellulosic absorbent fibers, where the thermoplastic polymer fibers are brought out on both surfaces: the surface of the upper web on the side of the absorbent and the surface of the back side absorbent element. Patent Document 1 teaches that the absorbent disclosed therein is soft and is unlikely to be curled since the thermoplastic polymer fibers function as a scaffold to hold other components of the absorbent, such as cellulose absorbent fibers.

Patent Document 2 also discloses an absorbent member comprising: fragments of a nonwoven material containing thermofusible fibers, where the thermofusible fibers are bonded to each other and have a three-dimensional structure before the fragments are formed; and hydrophilic fibers. Nonwoven fabric pieces having a three-dimensional structure are made by cutting the nonwoven fabric into small pieces using cutting means such as a cutting grinder. Thanks to this manufacturing method, the fragments have an indefinite shape, as shown in FIG. 1 and 3 in Patent Document 2, and essentially do not contain a part that could be considered as a flat surface. Patent Document 2 discloses an absorbent member according to a preferred embodiment in which pieces of nonwoven material are thermally fused to each other. Patent Document 2 says that empty spaces are formed inside the absorbent body because the nonwoven fabric pieces have a three-dimensional structure; and that the moisture-absorbing resilience is thus increased, and thus moisture absorption is increased.

Patent Document 3 also discloses a microfiber web comprising relatively dense microfiber nuclei with individual fibers or fiber bundles protruding from them, and also discloses that a nonwoven fibrous web obtained by bonding a microfiber web with wood pulp and absorbent polymer particles can be used as an absorbent element for use in an absorbent article. A microfiber web is made by stretching or tearing a web of sheet material, such as a nonwoven fabric. Accordingly, as in the case of using the nonwoven fabric fragments disclosed in Patent Document 2, they have an indefinite shape, and essentially do not contain a part that could be considered as a flat surface.

List of cited patent literature

Patent Document 1: US Patent Publication No. 2015/0366726

Patent Document 2: US Patent Publication No. 2010/0174259

Patent Document 3: US Patent No. 4813948

Brief description of the invention

The present invention relates to an absorbent element comprising: a plurality of fibrous clusters containing synthetic fibers; and a variety of absorbent fibers. The fibrous clusters are entangled with each other, or the fibrous clusters and absorbent fibers are interchanged. Each of the fibrous clusters contains two opposite base surfaces and a body surface that connects the two base surfaces. The number of fiber ends per unit area of the body surface is greater than the number of fiber ends per unit area in each of the base surfaces.

The present invention also relates to an absorbent element containing: a plurality of fibrous clusters containing synthetic fibers; and a variety of absorbent fibers. The fibrous clusters are entangled with each other, or the fibrous clusters and absorbent fibers are interchanged. Each of the fibrous clusters contains two opposite base surfaces and a body surface that connects the two base surfaces. Each of the fibrous clusters contains a protruding part of the fibrous bundle protruding outward from the surface of the body and containing a plurality of fibers.

Brief description of the drawings

In FIG. 1 is a schematic perspective view of an absorbent according to an embodiment of the present invention;

in fig. 2 is a diagram which schematically shows the deformed state of the absorbent shown in FIG. 1, in the compressed state of the absorbent;

in fig. 3(a) and 3(b) show schematic perspective views of fibrous clusters according to the present invention;

in fig. 4 is a diagram illustrating a method for manufacturing a fiber cluster according to the present invention;

in fig. 5(a) shows an electron microscope image (at 25x magnification) of an example of a fibrous cluster according to the present invention, and FIG. 5(b) is a diagram schematically illustrating a fibrous cluster imaged by an electron microscope as an example of a fibrous cluster included in the absorbent member shown in FIG. one;

in fig. 6 is a schematic perspective view of an apparatus for manufacturing an absorbent according to an embodiment of the present invention;

in fig. 7 is an enlarged side view of the second feeder (fiber cluster manufacturing apparatus) included in the manufacturing apparatus of FIG. 6.

Description of Embodiments

In the absorbent body disclosed in Patent Document 1, the plurality of synthetic fibers included in the absorbent body are each independent and therefore do not form one single group cluster. Accordingly, the effect of improving various properties is insignificant. For this reason, when an absorbent is used in an absorbent article, it may soon become curled and may not perform satisfactorily. Such problems are significant, especially when absorbing human excreted fluid, such as urine or menstrual blood.

When considering the synthetic fiber wads included in the absorbent members disclosed in Patent Documents 2 and 3, they have an indefinite shape, and their shape and dimensions are not uniform, as described above. For this reason, when using the synthetic fiber wad together with the wood pulp or the like, it is difficult to uniformly mix the synthetic fiber wads and the wood pulp, and the desired effect may not be obtained. Also, the synthetic fiber wads disclosed in the Patent Documents are made by cutting a nonwoven fabric made primarily from synthetic fibers and converted into small pieces by stretching or tearing the nonwoven fabric, whereby their surface is considered to be randomly rough. In an absorbent body containing a plurality of synthetic fiber clumps whose entire surface is rough, a plurality of synthetic fiber clumps can be confused with a relatively large binding force over their entire surface. As a result, the degree of freedom of movement of each synthetic fiber wad is substantially limited, and the softness of the absorbent body can be reduced. Also, when all the synthetic fiber wads included in the absorbent body are thermally fused, as in the preferred embodiment of the absorbent body according to Patent Document 2, movement of the synthetic fiber wads is limited. As a result, the rigidity of the absorbent body as a whole is increased and various properties such as flexibility may be reduced.

Accordingly, the present invention relates to an absorbent member having a very high resilience and a very high resilience after compression, which has the ability to elastically deform in response to an external force and can provide improved wearing comfort and perform better when used in an absorbent article. ; and to an absorbent article containing an absorbent element.

Hereinafter, the present invention is described with reference to the drawings relating to the preferred embodiment. In FIG. 1 shows an absorbent 10 as an embodiment of an absorbent according to the present invention. The absorbent element 10 contains fibrous clusters 11, consisting of a plurality of fibers 11F and absorbent fibers 12F.

The term "fiber cluster" in this specification refers to a clump of fibers formed by grouping a plurality of fibers. The fibrous cluster may be in the form of a small piece of a certain size cut, for example, from a synthetic fiber web. In particular, it is preferable to select a nonwoven fabric as a synthetic fiber web, cut a small piece of nonwoven fabric of a predetermined size and shape from the nonwoven fabric, and use a small piece of nonwoven fabric as a fiber cluster.

As described above, the fiber cluster in the form of a small piece of web, which is a preferred embodiment of the fibrous cluster according to the present invention, is made by cutting a piece from a fibrous web (preferably non-woven material) having a size larger than the size of the piece, rather from a large group of fibers, which is given the form of a leafy small piece (see Fig. 4). The plurality of fibrous clusters included in the absorbent body of the present invention is (each) a fibrous cluster in the form of a leafy small piece that has a high level of defined shape, unlike those made using conventional techniques such as those disclosed in Patent Documents 2 and 3.

In the absorbent body 10, a plurality of fibrous clusters 11 are intertwined with each other, or fibrous clusters 11 and absorbent fibers 12F are interchanged. In the absorbent body 10 according to the present embodiment, a plurality of fiber clusters 11 are intertwined and bonded with the constituent fibers (fibers 11F and 12F) of the absorbent body 10, thus constituting one large continuous fiber cluster. A configuration is also possible in which a plurality of fibrous clusters 11 are entangled with each other while the fibrous clusters 11 and absorbent fibers 12F are also entangled and bonded. In addition, usually a plurality of 12F absorbent fibers are also intertwined with each other. At least some of the plurality of fibrous clusters 11 included in the absorbent member 10 are entangled with other fibrous clusters 11 or absorbent fibers 12F. In the absorbent member 10, all of the plurality of fibrous clusters 11 included in the absorbent member 10 may be entangled with each other to form a single, large, continuous fibrous cluster, or a plurality of large, continuous, fibrous clusters may exist together without being bonded to each other.

The fibrous clusters 11 have very high flexibility and other properties. Accordingly, by incorporating the fibrous clusters 11 into the absorbent body, the resulting absorbent body, according to its inherent properties, has very high flexibility and other properties. In the absorbent body 10 according to the present invention, in addition to including the fibrous clusters 11, the fibrous clusters 11 are mixed and bonded to each other, or the fibrous clusters 11 and absorbent fibers 12F are also mixed and bonded to each other. Accordingly, the absorbent member 10 responds even better to an external force and thus has very high flexibility, very high resilience and very high resilience. For example, when the absorbent 10 according to the present invention is inserted into an absorbent article, the absorbent article can be bent under the influence of an external force (eg, body pressure of a wearer wearing the absorbent article) acting in different directions, and the absorbent article thus fits well. to the user's body.

In FIG. 2 schematically shows the deformed state of the absorbent 10 when the absorbent 10 is compressed by an external force F. In the absorbent 10 in which the fibrous clumps 11 and the absorbent fibers 12F which are the clumps exist together, where the absorbent 10 is likely to be suitable to bending, especially along the boundaries BL (along the dotted lines shown in Fig. 2) between the fibrous clusters 11 and the absorbent fibers 12F, due to the difference in stiffness between the fibrous clusters 11 and the absorbent fibers 12F. Boundaries BL, which function as bendable portions when the absorbent 10 is subjected to deformation, are typically present throughout the area of the absorbent 10, and thus the absorbent 10 can be bent when subjected to any external force and can also quickly return to its original state due to the ability to recover from compression of the fibrous clusters 11 when the external force is removed. Such deformation/recoverability properties of the absorbent element 10 are exhibited not only when the absorbent element 10 is compressed, but also when the absorbent element 10 is twisted. thighs of the wearer of the absorbent article. Accordingly, the absorbent member 10 can be twisted about an imaginary axis of rotation extending in the front-to-back direction of the wearer due to the movement of the two hips as the wearer walks. Even so, since the absorbent body 10 has good deformability/recoverability, the absorbent body 10 can easily recover from a deformed state in response to an external force that causes twisting from two thighs. Accordingly, the absorbent article is unlikely to curl, and thus a good fit to the wearer's body can be ensured.

As described above, in the absorbent body 10, the fiber clusters 11 are entangled with each other, or the fiber clusters 11 and the absorbent fibers 12F are entangled with each other. As used herein, the term "entanglement" and other similar terms used to express that the fibrous clusters 11 or the like are intertwined encompass the following configurations: A and B.

Configuration A: The fibrous clusters 11 or the like are bonded to each other by entanglement of the constituent fibers 11F of the fibrous clusters 11 with each other rather than by fusing them together.

Configuration B: fibrous clusters 11 or similar structures not connected to each other when the absorbent body 10 is in the natural state (a state in which no external force is applied), but when an external force is applied to the absorbent body 10, fibrous clusters 11 or the like structures bind to each other as a result of entanglement with each other of their constituent 11F fibers. As used herein, "an external force is applied to the absorbent 10" means, for example, that a state in which a deforming force is applied to the absorbent 10 in the absorbent article occurs at the time of wearing.

As described above, in the absorbent body 10, some fibrous clusters 11 are associated with other fibrous clusters 11 or absorbent fibers 12F by entanglement, as in configuration A, and some fibrous clusters 11 have the ability to be entangled with other fibrous clusters 11 or absorbent fibers 12F, as in configuration B. Such entanglement bonding is an important feature in further effectively exercising the above-described beneficial properties of the absorbent body 10. However, the absorbent body 10 preferably exhibits the "entanglement" appearance of configuration A in terms of shape retention. The bonding due to fiber entanglement is created only by fiber entanglement, without binder or fusion, and thus the degree of freedom of movement of the individual entangled elements (fiber clusters 11 and absorbent fibers 12F) is high compared to bonding due to "fiber fusion" as , for example, is disclosed in Patent Document 2. Accordingly, individual elements can move within the range in which clumps of elements are formed and can maintain its integrity. As described above, since the plurality of fibrous clusters 11 included in the absorbent member 10 are relatively loosely bonded to each other, or because the fibrous clusters 11 and absorbent fibers 12F included in the absorbent member 10 are relatively loosely bonded, the absorbent member 10 has a weak the ability to maintain shape and can be deformed in response to the application of an external force. Accordingly, high levels of shape retention, resiliency and resilience are achieved.

However, as in configuration B, not all of the bonds formed through the fibrous clusters 11 in the absorbent body 10 need to be formed by "entangling", and other bonding conditions may be involved in part of the absorbent body 10, including bonding through the use of a binder. .

Considering the more reliable presentation of the above-described beneficial effects of the absorbent member 10, the total number of "entangled fibrous clusters 11" that correspond to configuration A and "entangling fibrous clusters 11" that correspond to configuration B is preferably 50 % or more, more preferably 70% or more, and even more preferably 80% or more, of the total number of fibrous clusters 11 in the absorbent element 10.

From the same point of view, the number of fibrous clusters 11 having the "entanglement" structure according to configuration A is preferably 70% or more, and particularly preferably 80% or more, of the total number of fibrous clusters 11 having parts linking them to other fibrous cluster 11 or absorbent fibers 12F.

The main feature of the absorbent element 10 lies in the external shape of the fibrous clusters 11. In FIG. 3 shows two exemplary external shapes of fibrous clusters 11. Fiber cluster 11A shown in FIG. 3(a) has a quadrangular prismatic shape, more specifically a cuboid shape. Fiber cluster 11B shown in FIG. 3(b) is disk-shaped. The fibrous clusters 11A and 11B are the same in that they contain two opposite base surfaces (base planes) 111 and a body surface 112 (body side surface) that connects the two base surfaces 111. The base surfaces 111 and the body surface 112 are (each) part , essentially free of unevenness, in terms of level, to assess the degree of unevenness of the surface of the product formed mainly from this type of fiber.

The cuboid fiber cluster 11A shown in FIG. 3(a) contains six flat front surfaces. Of the six faces, the two opposite faces having the largest area correspond to the base surfaces 111, and the remaining four faces correspond to the surfaces 112 of the body. Base surfaces 111 and body surfaces 112 intersect with each other, more specifically, they are at right angles to each other.

The disk-shaped fibrous cluster 11B shown in FIG. 3(b) comprises two opposing flat faces, each in the shape of a circle in plan view, and a curved peripheral surface connecting the two flat faces. The two flat front surfaces correspond to the base surfaces 111 and the peripheral surface corresponds to the body surface 112.

The fiber clusters 11A and 11B are also the same in that the body surfaces 112 have a quadrangular shape, more specifically, a rectangular shape in plan view.

The plurality of fiber clusters 11 contained in the absorbent body 10 differ from the nonwoven fabric fragments disclosed in Patent Document 2 and from the microfiber web disclosed in Patent Document 3, which are fibrous clumps having an indefinite shape, in that each fibrous cluster 11 is a "shaped fibrous bolus" that comprises two opposing reference surfaces 111 and a body surface 112 that connects the two reference surfaces 111, as in the case of fibrous clusters 11A and 11B shown in FIG. 3. In other words, when considering the fibrous cluster 11 arbitrarily selected from the fibrous clusters 11 contained in the absorbent member 10 (when viewed using, for example, an electron microscope), a plurality of perspective shapes are obtained by considering one fibrous cluster 11, since the shape in the perspective of the fibrous cluster 11 changes depending on the angle of view. Accordingly, each of the plurality of fibrous clusters 11 contained in the absorbent member 10 has a specific perspective shape that includes two opposing base surfaces 111 and a body surface 112 that connects the two base surfaces 111 as one of the plurality of perspective shapes. The plurality of nonwoven fabric and microfiber web portions respectively contained in the absorbent members disclosed in Patent Documents 2 and 3 are substantially free of "faces" or "surfaces" like base surfaces 111 and body surface 112, or in other words, wide parts, and thus they have different external shapes and thus do not have a "defined shape".

As described above, when the plurality of fibrous clusters 11 contained in the absorbent member 10 are (each) a "shaped fibrous lump" defined by base surfaces 111 and one or more numbers of body surfaces 112, such fibrous clusters 11 exhibit increased distribution uniformity in the absorbent body 10, as compared to fibrous boluses having an indefinite shape as disclosed in Patent Documents 2 and 3. Accordingly, the effects (flexibility, resiliency, resilience and the like properties of the absorbent body) expected to resulting from the incorporation of fibrous lumps, such as fibrous clusters 11, into the absorbent body 10, are stable. Also, especially in the case of using the cuboid fiber cluster 11A as shown in FIG. 3(a), the outer surface consists of six faces, i.e. of two base surfaces 111 and four surfaces 112 of the body. Accordingly, the fiber cluster 11 having the shape of a cuboid, as shown in FIG. 3(a) may have relatively more points of contact with other fiber clusters 11 or absorbent fibers 12F than a disk-shaped fiber cluster 11B consisting of three outer surfaces as shown in FIG. 3(b), and thus the former has a higher entanglement capability, which can lead to an increased shape retention and other properties.

In the fibrous cluster 11, the total area of the two base surfaces 111 is preferably greater than the total area of the surface(s) 112 of the body(s). This means that in the cuboid fiber cluster 11A as shown in FIG. 3(a), the sum of the respective areas of the two base surfaces 111 is greater than the sum of the respective areas of the four body surfaces 112, and in the disk-shaped fiber cluster 11B shown in FIG. 3(b), the sum of the respective areas of the two base surfaces 111 is greater than the area of the body surface 112, which is the peripheral surface of the disk-shaped fibrous cluster 11B. In each of the fiber clusters 11A and 11B, the reference surfaces 111 are the surfaces having the largest area among the plurality of its surfaces.

The fibrous cluster 11, which is a "fibrous lump having a certain shape" defined by two reference surfaces 111 and one or more body surfaces 112 that(s) intersect(s) with two reference surfaces 111, can be provided by using a manufacturing method, different from conventional technologies. A preferred method for manufacturing fiber cluster 11 includes, as shown in FIG. 4, cutting the fibrous sheet material 10bs (a web containing the same composition as the fibrous cluster 11 and a larger fibrous cluster 11) as a starting material into lengths of defined shapes using cutting means such as a cutter. The plurality of fibrous clusters 11 made by this method have a uniform defined shape and dimensions compared to those made by conventional techniques as disclosed in Patent Documents 2 and 3. FIG. 4 is a diagram illustrating a method for manufacturing cuboid fiber clusters 11A as shown in FIG. 3(a) and the dotted lines shown in FIG. 4, cut lines are indicated. The absorbent body 10 contains a plurality of fibrous clusters 11 of the same shape and the same size, obtained by cutting the fibrous web into segments of a certain shape in this way. As described above, as the fibrous sheet material 10bs, a non-woven material is preferably used.

Fibrous clusters 11A in the form of rectangular parallelepipeds, as shown in FIG. 3(a) is made by cutting the fibrous sheet material 10bs into segments predetermined in length in a first direction D1 and a second direction D2 that intersects (more specifically: at right angles to) the first direction D1 as shown in FIG. . 4. Directions D1 and D2 (each) are predetermined directions in the surface plane of the web 10bs, and the web 10bs is cut along the Z thickness direction at right angles to the surface direction. In a plurality of cuboid-shaped fibrous clusters 11A obtained by cutting the fibrous sheet material 10bs into so-called "cubes" in this way, cut surfaces (i.e., surfaces that come into contact with cutting means, such as a cutter when cutting), generally correspond to the surfaces 112 of the body, and the uncut surfaces (i.e., the surfaces not in contact with the cutting means) correspond to the base surfaces 111. The base surfaces 111 are the front and back surfaces of the web 10bs (surfaces located at right angles to the Z thickness direction ), and as described above, the base surfaces 111 have the largest area among the plurality of surfaces of the fiber cluster 11A.

The description of the fiber cluster 11A above can be basically applied to the disk-shaped fiber cluster 11B shown in FIG. 3(b). Its only significant difference from the fibrous cluster 11A is the cutting pattern of the fibrous sheet material 10bs. To obtain fibrous clusters 11B by cutting the sheet material 10bs into lengths of certain shapes, the sheet material 10bs can be cut into round-shaped lengths according to the shape of the fibrous clusters 11B in plan view.

Also, the outer shape of the fibrous cluster 11 is not limited to those shown in FIG. 3, both reference surfaces 111 and body surfaces 112 may be non-curved flat surfaces, such as surfaces 111 and 112 shown in FIG. 3(a), or curved surfaces such as the body surface 112 (peripheral surface of the disk-shaped fibrous cluster 11B) shown in FIG. 3(b). The base surfaces 111 and the body surface 112 may have the same shape and the same dimensions, and specifically, for example, the outer shape of the fiber cluster 11A may have a cubic shape.

As described above, two types of surfaces (i.e., base surface 111 and body surface 112) of the fibrous cluster 11 (11A or 11B) can be classified as a cut surface (body surface 112) created by cutting the fibrous sheet material 10bs using cutting means, for example, a cutting device, in the manufacture of the fibrous cluster 11; and the uncut surface (base surface 111) being the original surface of the web 10bs that did not come into contact with the cutting means. Whether or not the surface is a cut surface, the body surface 112, which is the cut surface, has the feature that the number of fiber end portions per unit area is greater than that of the base surface 111, which is the uncut surface. As used herein, the term "fiber end" refers to the end of the fibrous cluster 11 included in the fiber 11F in its longitudinal direction. Typically, there are fiber ends in base surface 111, which is an uncut surface; however, since the body surface 112 is a cut surface created by cutting the fibrous sheet material 10bs, many fiber ends are the cut ends of the constituent fibers 11F formed by cutting, is in the entire body surface 112, or in other words, the number of fiber ends per unit area more than in the base surface 111.

The fiber end portions present on each surface of the fiber cluster 11 (base surfaces 111 and body surface 112) are suitable for forming entanglements between the fiber cluster 11 and other fiber clusters 11 and the absorbent fibers 12F included in the absorbent member 10. Also, in in general, the entanglement ability can be further increased by increasing the number of fiber ends per unit area, resulting in enhanced various properties of the absorbent member 10, such as shape retention. As described above, the number of fiber ends on each surface of the fiber cluster 11 is not the same, and the number of fiber ends per unit area may satisfy the following quantitative relationship: "body surface 112 > base surface 111". Because of this, the entanglement of the fibrous cluster 11 with other fibers (the other fibrous clusters 11 and the absorbent fibers 12F) varies depending on the surface of the fibrous cluster 11, and the entanglement ability of the body surface 112 is higher than the entanglement ability of the base surface 111. Specifically, the binding strength due to entanglement with other fibers through the body surface 112 is greater than the binding force resulting from entanglement with other fibers through the reference surface 111, and a difference can be made between the binding force resulting from entanglement with other fibers through the reference surface 111 and through the body surface 112 within one fibrous cluster 11.

As described above, the plurality of fibrous clusters 11 included in the absorbent member 10 become entangled with other fibers (other fibrous clusters 11 and absorbent fibers 12F) at their periphery under the influence of two types of bonding forces. With this configuration, the absorbent member 10 has both properties of adequate softness and adequate strength (shape retention). By using an absorbent member 10 having very high properties as described above as an absorbent member for an absorbent article according to the conventional method, great wearing comfort can be provided to the wearer of the absorbent article, and damage to the absorbent member 10 adversely caused by an external force, for example , the body pressure of the wearer of the absorbent article can be effectively prevented.

In particular, in the fibrous cluster 11 (11A or 11B) shown in FIG. 3, the total area of the two base surfaces 111 is greater than the total surface area 112 of the body, as described above. This means that the total area of the base surfaces 111 is larger, but they contain a relatively smaller number of fiber ends per unit area and, therefore, have a relatively lower ability to entangle with other dies than the body surfaces 112, which have opposite properties. Accordingly, in the fiber cluster 11 (11A or 11B) shown in FIG. 3, entanglement with other peripheral fibers (other fiber clusters 11 and absorbent fibers 12F) is more likely to be limited, compared to a fiber cluster in which fiber ends are evenly present over the entire surface. Also, even when the fibrous cluster 11 is entangled with other peripheral fibers, the fibrous cluster 11 is entangled with other peripheral fibers with a relatively weaker binding force. As a consequence, it is unlikely that a large mass will be generated, and thus a very high flexibility can be given to the absorbent member 10.

In contrast, the nonwoven fabric pieces disclosed in Patent Document 2 and the microfiber web disclosed in Patent Document 3 were made by cutting the fibrous sheet material into lengths of indefinite shapes using a cutting machine such as a cutting shredder as described above. For this reason, they are not fibrous clusters in the form of leafy small pieces shaped with "surfaces" like base surfaces 111 and body surface 112. In addition, during the manufacture of fiber clusters, an external force is applied to all fiber clusters during the cutting process. Accordingly, the fiber ends constituting the clusters are arranged randomly in all fiber clusters, and thus the above-described beneficial effects provided by the fiber ends are not significantly exhibited.

Taking into account the achievement of the above-described beneficial effects provided by the end parts of the fibers, the ratio of N _{1 - the} number of end parts of the fibers per unit area of the base surfaces 111 (uncut surfaces), to N ₂ - the number of end parts of the fibers per unit area of the surface 112 of the body (cut surface ), i.e. N ₁ /N _{2 is} preferably 0 or more, and more preferably 0.05 or more, and preferably 0.90 or less, more preferably 0.60 or less, ensuring 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 N ₁ of the end parts of fibers per unit area of the base surfaces 111 preferably 0 end portions of the fibers / mm ² or more, and more preferably - 3 end portions of the fibers / mm ² or more, and preferably 8, the end portions of the fibers / mm ² or less, and more preferably 6 fiber ends/mm ² or less.

Number N ₂ the end portions of the fibers per unit of surface area 112 of the body 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 the 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 of body surface 112 and the number of fiber ends per unit area of base surfaces 111 are determined according to the following method.

A method for determining the number of fiber ends per unit area in each surface of a fiber cluster .

A sample of the fiber-containing element (fiber cluster) as an object is attached to the sample table using a piece of double-sided adhesive paper tape (NICE TACK NW-15, commercially available from Nichiban Co., Ltd.). The sample is then subjected to a platinum coating. Coating was carried out using an E-1030 ion sprayer (name of apparatus) commercially available from Hitachinaka Seiki Co., Ltd. for spraying for 120 seconds. The cut surface (base surface or body surface) of the sample is viewed using a JCM-6000 electron microscope available from JEOL at 100x magnification. In the image obtained at 100x magnification, a rectangular area 1.2 mm long and 0.6 mm wide is determined at an arbitrarily chosen location of the observed surface (base surface or body surface), and the viewing angle and other conditions are adjusted so that the area rectangular area was 90% or more of the resulting image. Then count the number of end parts of the fibers located in a rectangular area. However, in some cases, in a 100x image, the viewable surface of the fibrous cluster may be less than 1.2 mm x 0.6 mm, and thus the area of the rectangular area may be less than 90% of the resulting image. In such cases, the magnification is adjusted to a value greater than 100 times, and then the number of fiber ends located in the rectangular area is counted on the surface being viewed in the manner described above. When used in this specification, the phrase “fiber ends” to be counted refers to the longitudinal ends of the fibers constituting the fiber cluster, and if the parts other than the longitudinal ends (middle parts in the longitudinal direction) of the constituent fibers protrude from the observed surfaces, then the middle parts located in the longitudinal direction are not considered. Then, the number of fiber ends per unit area of the observed surface (base surface or body surface) of the fiber cluster is calculated using the following equation. In ten fiber clusters, the number of fiber ends per unit area of the base surface and the same number per unit area of the body surface are counted in the same manner as described above, and the average value of the counted values is determined as the number of fiber ends per unit area of the target surface.

Number of fiber ends per unit area of the target surface (base surface or body surface) of the fiber cluster (fiber ends/mm ² ) = number of fiber ends in a rectangular area (1.2 x 0.6 mm)/area of a rectangular area (0 .72 mm ² ).

In the case where the base surface 111 of the fiber cluster 11 has a rectangular shape in plan view, as the fiber cluster 11A shown in FIG. 3(a), each short side 111a of a rectangular shape is preferably less than or equal to the thickness of the absorbent element 10 containing the fibrous cluster 11 (11A) in order to improve the even distribution of the fibrous clusters 11 in the absorbent element 10.

The ratio of the length of the short side 111a to the thickness of the absorbent member 10 (largest/smallest) is preferably 0.03 or more, and more preferably 0.08 or more, and preferably 1.0 or less, and more preferably 0.5 or less .

The thickness of the absorbent member 10 is preferably 1 mm or more, more preferably 2 mm or more, and preferably 10 mm or less, and more preferably 6 mm or less. The thickness of the absorbent member 10 is measured using the following method.

Absorbent Body Thickness Measurement Method

The object to be measured (absorbent 10) is usually placed on a horizontal surface so that it is not wrinkled or warped, and then the thickness of the object to be measured is measured under a load of 5 cN/cm ² . Specifically, the thickness measurement is carried out using, for example, a PEACOCK DIAL UPRIGHT GAUGES R5-C thickness gauge (commercially available from OZAKI MFG. CO. LTD.). At this time, a plate (an acrylic plate with a thickness of about 5 mm) is applied, having a round or square shape in the top view and such dimensions that a load of 5 cN/cm ^{2 is created} on the measurement object between the end of the thickness gauge probe and the cut-out measurement object, and then the thickness is measured. . The thickness measurement is carried out at ten points, the average value of the measured values is calculated and it is taken as the thickness of the measurement object.

The dimensions and other parameters of each part of the fibrous cluster 11 (11A or 11B) are preferably set in the manner described below. The dimensions of each part of the fibrous cluster 11 can be measured using an image obtained with an electron microscope or a similar image obtained during the outer shape identification operation of the fibrous cluster 11 described below.

In case the base surface 111 has a rectangular shape in plan view as shown in FIG. 3(a), the length of the short side 111a, L1 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more, and preferably 10.0 mm. or less, more preferably 6.0 mm or less, and even more preferably 5.0 mm or less.

The length of the long side 111b, L2 of the rectangular-shaped base surface 111 in plan view is preferably 0.3 mm or more, more preferably 1.0 mm or more, and even more preferably 2.0 mm or more, and preferably 30.0 mm or less, more preferably 15.0 mm or less, and even more preferably 10.0 mm or less.

If the base surface 111 has the largest area among the plurality of surfaces of the fiber cluster 11, as shown in FIG. 3, the length of the long side 111b, L2 is the same as the maximum overall length of the fibrous cluster 11, and the maximum overall length is the same as the diameter of the base surface 111, which is circular in top view, of the disc-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 preferably 1.0 or less, and more preferably 0.5 or less. According to the present invention, the top view shape of the base surface 111 is not limited to a rectangular shape as shown in FIG. 3(a), and may be a square shape, or in other words, the ratio of the length of the two sides at right angles to each other (L1/L2) may be 1.0.

The thickness T of the fibrous cluster 11, or in other words, the length T between two opposite base surfaces 111, is preferably 0.1 mm or more, more preferably 0.3 mm or more, and preferably 10.0 mm or less and more preferably 6.0 mm or less.

It is also preferable that in the absorbent element 10 the fibrous clusters 11 are distributed densely and uniformly throughout the absorbent element 10, since the response to an external force is likely to be isotropic. From this point of view, in the bidirectionally projected views of the absorbent member 10 at right angles to each other, it is preferable that there are superimposed portions of a plurality of fibrous clusters 11 in an arbitrary unit area of 10 mm ² . Position 11Z in FIG. 1 and 2 indicate the superimposed portions of a plurality of fibrous clusters 11. As used herein, the phrase "projected views in two directions of the absorbent member 10 at right angles to each other" will typically include a projected view in the thickness direction of the absorbent member (or, in other words, the projected view when viewing the absorbent from the side of the surface facing the skin, or the surface not facing the skin of the consumer, the absorbent element) and the projected view in the direction located at right angles to the thickness direction (or, in other words, the projected view when viewing the absorbent element on its side).

In FIG. 5(a) is an electron microscope image of a fibrous cluster according to an embodiment of the present invention, and FIG. 5(b) is a diagram schematically illustrating the fibrous cluster 11 made according to an electron microscope image. As shown in FIG. 5, the plurality of fibrous clusters 11 included in the absorbent member 10 may (each) be composed of a body body 110 and a fiber protrusion 113 having fiber 11F protruding outward from the body body 110 and having a fiber density lower than that of the body body. 110 body (contains a small amount of fibers per unit area). The absorbent member 10 may comprise fibrous clusters 11 not containing projecting fiber portions 113, or, in other words, fibrous clusters 11 consisting (each) of a main body part 110. The fiber extension 113 may comprise either one type of fiber end present on the base surface 111, or a fiber end on the body surface 112 of the fiber cluster 11 described above, and one type of fiber end included in the fiber extension 113 projecting outwardly. from the corresponding surface of the fibrous cluster 11.

As described above, the main body part 110 is the part defined by the two opposing base surfaces 111 and the body surface 112 that connects the two base surfaces 111. The main body part 110 is an essential part of the fibrous cluster 11 and forms the outer shape of the shaped fibrous cluster 11. Various properties of the fibrous cluster 11, such as high flexibility, resilience, and resilience, are much more dependent on the main body part 110. On the other hand, the fiber projection 113 mainly contributes to increasing the entanglement between the plurality of fibrous clusters 11 or the entanglement between the fibrous clusters 11 and the absorbent fibers 12F in the absorbent body 10, to thereby ensure a direct effect on improving the shape retention of the absorbent body 10 , and also influences the even distribution of the fibrous clusters 11 in the absorbent member 10, so as to indirectly enhance the beneficial effects provided by the body body 110.

The body main body 110 has a higher fiber density, or in other words, more fibers per unit area than the number of fibers per unit area in the fiber projection 113 . Usually also the fiber density in the most basic body part 110 is uniform. The mass fraction of the main body part 110 relative to the total weight of the fibrous cluster 11 is usually at least 40 wt.% or more, preferably 50 wt.% or more, more preferably 60 wt.% or more, and even more preferably 85 wt. .% or more. The main body part 110 and the fiber protruding part 113 can be distinguished from each other by performing the following external shape identification operation.

The operation of identifying the outer shape of the main body part 110 of the fibrous cluster 11 in the absorbent member 10 can be performed by checking the "boundaries" between the main body part 110 and other parts, focusing on the difference in fiber density (difference in the number of fibers per unit area), fiber type, fiber diameter and similar parameters between the fibrous cluster 11 and its peripheral parts. The main body 110 has a higher fiber density than the protruding portion 113 of the fibers located in the surrounding area of the main body 110; and typically, the synthetic fibers that make up the fibers of the main body 110 differ from the 12F absorbent fibers (which are typically cellulosic fibers) in terms of their characteristics and/or dimensions. Accordingly, even in the absorbent body 10 in which a plurality of fibrous clusters 11 and absorbent fibers 12F are in a mixed state, the boundaries described above can be easily confirmed by focusing on the above difference. The boundaries identified in the above manner correspond to the peripheries (sides) of the base surface 111 and the body surface 112. Through such a boundary check operation, the base surface 111 and the body surface 112 are identified, and ultimately the main body part 110 is identified. The boundary checking operation can be performed by viewing the target object (absorbent member 10) from multiple viewing angles, if necessary, using an electron microscope. In particular, in the case where the fibrous clusters 11 included in the absorbent body 10 are those in which "the total area of the two base surfaces 111 is greater than the total body surface area 112", as is the case with the fibrous clusters 11A and 11B shown in FIG. . 3, especially in the case where the base surfaces 111 have the largest area of the fibrous cluster 11, such base surfaces 111 having the largest area can be identified relatively easily, and thus the outer shape identification operation of the main body part 110 can be safely performed. .

As shown in FIG. 5, a fiber projection 113 is formed from one or more constituent fibers 11F from the body body 110 projecting outwardly from at least one of the base surfaces 111 and the body surface 112 that define the outer surface of the body body 110. In FIG. 5 shows the fibrous cluster 11 as seen from the top side of the base surface 111 (the surface having the largest area among the plurality of surfaces of the fibrous cluster 11), and a fiber projecting portion 113 formed from a plurality of fibers 11F protruding from the body surface 112 that intersects with base surface 111.

There are no particular restrictions on the shape of the protruding portion 113 of the fiber. The fiber extension 113 may be formed from only one fiber 11F or may be composed of a plurality of fibers 11F, such as the fiber bundle extension 113S described below. The protruding part 113 of the fiber also includes a longitudinal end part of the fiber 11F protruding from the main part 110 of the body. However, in addition to or instead of such a fiber end portion, the fiber projection 113 may comprise a portion different from the longitudinal ends (the middle portion in the longitudinal direction) of the 11F fiber. Specifically, in the fiber cluster 11, a part different from both longitudinal ends (i.e., the middle part in the longitudinal direction) constituting the fibers 11F may protrude (protrude) in a loop outwardly from the main body part 110 from both longitudinal ends of the fiber 11F, located in the main part 110 of the body. In this case, the fiber projection 113 includes a loop-shaped fiber projection 11F. In other words, among the fiber projections 113, the fiber projections 113 whose ends are brought out represent one type of fiber end.

As described above, the main function of the fiber projection 113 is to cause the plurality of fiber clusters 11 included in the absorbent member 10 to be entangled with each other, or to cause the fiber clusters 11 and the absorbent fibers 12F to be entangled with each other. In general, by increasing the length of the fiber projection 113 from the main body body 110, or by increasing the thickness of the fiber projection 113, or by increasing the number of fiber projections 113 in one fiber cluster 11, the bonding between objects entangled by the fiber projection 113, is amplified, and thus the entangled objects are unlikely to separate from each other. Accordingly, the predetermined effects according to the present invention are more stable.

In case the fibrous cluster 11 is a fibrous cluster obtained by cutting the fibrous sheet material 10bs into certain shapes as shown in FIG. 4, a relatively large number of fiber projections 113 are on the body surface 112 of the fiber cluster 11, which is the cut surface; on the other hand, on the base surface 111, which is the uncut surface, there are no fiber projections 113, or if there are, the number of fiber projections 113 is less than on the body surface 112. Thus, the reason why the fiber projections 113 are concentrated on the body surface 112, which is the cut surface, is because the majority of the fiber projections 113 are fluff created by cutting the fibrous sheet material. Specifically, along the entire body surface 112 formed by cutting the fibrous sheet material 10bs, a cutting means such as a cutting tool is rubbed when cutting the fibrous sheet material, and thus fluff is likely to be generated from the fibers 11F included in the web 10bs. or, in other words, pushing is highly likely to occur. On the other hand, the base surface 111, which is the uncut surface, is not rubbed by the cutting means, and thus the formation of fluff (ie, fiber projections 113) is unlikely.

The distance L1a (distance in the first direction, see Fig. 4) and the distance L2a (distance in the second direction, see Fig. 4) of the cutting lines when cutting the fibrous sheet material 10bs is preferably 0.3 mm or more, and more preferably 0. 5 mm or more, and preferably 30.0 mm or less, and more preferably 15.0 mm or less, in view of facilitating the formation of the fiber projections 113 described above and providing the dimensions necessary for the fiber cluster 11 to manifestation of the desired effect.

As shown in FIG. 5, the fiber cluster 11 includes a fiber bundle extension 113S containing a plurality of fibers 11F and projecting outwardly from the body main body 110, more specifically, from the body surface 112, as one type of fiber extension 113. At least one fiber projection 113 of the fiber cluster 11 may be a fiber bundle projection 113S. The protruding portion 113S of the fiber bundle is a collection of a plurality of fibers 11F protruding from the surface 112 of the body, and characterized in that the length of the protrusion from the surface 112 of the body is greater than the length of the protruding portion 113 of the fiber. The protruding portion 113S of the fibrous bundle may be present on the base surface 111; however, typically, as shown in FIG. 5, the protruding portion 113S of the fiber bundle is located on the surface 112 of the body. Thus, there is no tuft projection 113S on the base surface 111, or if there is, the number of tuft projections 113S on the base surface 111 is less than that on the body surface 112. The reason for this is the same as the reason that the fiber projections 113 are mainly on the body surface 112, which is the cut surface described above.

Since each fibrous cluster 11 contains a fibrous bundle projection 113S described above, which is a large fiber projection 113 that is long and thick, the entanglement between the fibrous clusters 11 or the entanglement between the fibrous clusters 11 and the absorbent fibers 12F is further increased. As a result, the effect of the present invention provided by the fibrous clusters 11 is more stable. The protruding portion 113S of the fibrous bundle is easily formed by carrying out the above-described operation of cutting the fibrous sheet material 10bs under conditions where fluff is likely to be generated (see FIG. 4).

The protrusion length of the protruding portion 113S of the fibrous bundle from the main body part 110 (i.e., from the body surface 112 (from the cut surface) is preferably 0.2 mm or more, and more preferably 0.5 mm or more, and preferably 7 0 mm or less, and more preferably 4.0 mm or less The protrusion length of the protruding portion 113S of the fibrous bundle can be measured by performing the outer shape identification operation of the fibrous cluster 11 (boundary checking operation) described above. cluster 11 is placed on a transparent acrylic microscope sample table available from Keyence Corporation (at 50x magnification) and attached to it with a piece of double-sided adhesive tape available from 3M Company, and the outer shape of fibrous cluster 11 is identified , performing the operation of identifying the outer shape.Next, the length of the protruding portion of the fiber 11F protruding from the outer shape, and the measured projection length is defined as the projection length of the projection 113S of the fiber bundle.

In the protruding portion 113S of the fiber bundle, preferably, a plurality of constituent fibers 11F are thermally fused to each other. Such a thermally fused part of the fibrous bundle projection 113S generally has a greater overall thickness in a direction at right angles to the longitudinal direction of the fibrous bundle projection 113S (where the total thickness corresponds to the diameter in the case where the cross section of the thermally fused portion is circular) as opposed to from other parts (thermally non-fused parts) of the protruding part 113S of the fibrous bundle. Since the fibrous bundle projection 113S contains such a thermally fused portion, which can also be called a "large diameter portion", the strength of the fibrous bundle projection 113S itself increases, and as a result, entanglement between the fiber clusters 11 by the fibrous bundle projection 113S or entanglement between the fiber clusters 11 and the absorbent fibers 12F are further increased by the fibrous bundle projection 113S. The fibrous bundle projection 113S containing the thermally fused portion is advantageous in that the fibrous bundle projection 113S itself has improved strength, shape retention, and other properties not only when it is in a dry state, but also when it is in a wet state. due to moisture absorption. Thus, in case the absorbent body 10 is used in an absorbent article, the effects provided by the presence of the fibrous clusters 11 described above can be stably exhibited due to the favorable properties described above, not only when the absorbent body 10 is in a dry state, but also, when the absorbent 10 is in a wet state, due to the absorption of fluid exuded by the person, such as the urine or menstrual blood of the user. The fibrous bundle protruding portion 113S containing the thermally fused portion can be manufactured by using "the fibrous web containing the thermally fused portion of constituent fibers" as the fibrous sheet material 10bs in the step of manufacturing the fiber clusters 11 (in other words, the step of cutting the fibrous sheet material 10bs to obtain fibrous clusters 11) as shown in FIG. 4.

The component parts of the fibers 11F of the fibrous cluster 11 contain synthetic fibers. The synthetic fibers used as the 11F fibers are preferably non-absorbent synthetic fibers. If the constituent fibers 11F of the fibrous cluster 11 are non-absorbent fibers, the beneficial effects (effects of improving shape retention, flexibility, resilience, compression recovery, wear resistance, and the like) provided by the presence of the fibrous clusters 11 described above can be are stable not only when the absorbent 10 is in a dry state, but also when the absorbent 10 is in a wet state due to the absorption of moisture (liquid excreted by a person, such as urine or menstrual blood). The amount of synthetic fibers used as a constituent of the fibers 11F of the fiber cluster 11 is preferably 90 wt.% or more of the total mass of the fiber cluster 11, and most preferably 100 wt.%, or, in other words, most preferably, the fiber cluster 11 consisted only of synthetic fibers. The beneficial effects provided by the presence of the fibrous clusters 11 described above are more stable, especially when non-absorbent synthetic fibers are used as a constituent of the 11F fibers.

It will be readily understood by those skilled in the art that the term "absorbent" as used herein means the ability of a material to absorb moisture, such as the ability of a pulp to absorb moisture. Similarly, it is also easy for those skilled in the art to understand that thermoplastic fibers are not absorbent. The level of moisture absorption of fibers, such as synthetic fibers, can be determined based on the amount of moisture content measured according to the following method. The moisture content of the absorbent fibers is preferably 6.0% or more, and more preferably 10.0% or more. On the other hand, the moisture content of the non-absorbent fibers is preferably less than 6.0%, and more preferably less than 4.0%. When the moisture content is less than 6.0%, it is determined that the fibers are not absorbent fibers. At a moisture content of 6.0% or more, the fibers are determined to be absorbent fibers.

Moisture content measurement method

The moisture content was calculated based on the moisture content test method according to JIS P8203 (JIS - Japanese Industrial Standard). Specifically, the fibrous sample was left to age in the laboratory at 40° C. and 80% relative humidity (RH) for 24 hours. Then the mass W (g) of the fibrous sample was weighed in the laboratory until absolutely dry. Thereafter, the fibrous sample was left in an electric dryer (for example, commercially available from Isuzu Seisakusho, Co., Ltd.) at 105 ± 2°C for one hour to completely dry the fibrous sample. Then, in the laboratory under standard conditions: at a temperature of 20 ± 2°C and a relative humidity of 65 ± 2%, a fibrous sample wrapped in a plastic wrap (Saran Special Wrap is a registered trademark) available commercially from Asahi Kasei Corporation was placed in a glass desiccator (for example, available from Tech-Jam) containing Si silica gel (for example, available from Toyota Kako Co., Ltd.) and allowed to age until the temperature of the fiber sample reached 20 ± 2°C. Thereafter, the constant mass W' (g) of the fiber sample was measured and the moisture content of the fiber sample was determined using the following equation:

Moisture content (%) = (W-W’/W’) × 100.

In view of achieving very high effects in the fields of shape retention, flexibility, resilience, compression recovery, wear resistance and other properties, regardless of whether the absorbent body 10 is in a dry state or in a wet state, the fibrous cluster 11 should preferably have a three-dimensional structure. in which thermoplastic fibers are thermally fused together.

In order to obtain a fibrous cluster 11 in which a plurality of thermally fused parts are three-dimensionally distributed, the synthetic fibers used as a constituent of the fibers 11F of the fibrous cluster 11 preferably contain a plurality of thermoplastic fibers, and more preferably the fibrous cluster 11 is composed of thermoplastic fibers. Also, if a constituent part of the fibers 11F of the fibrous cluster 11 contains thermoplastic fibers, the above-described preferred shape of the protruding portion 113S of the fibrous bundle containing the thermally fused portion can be obtained.

To obtain a fibrous cluster 11 in which a plurality of thermally fused parts are three-dimensionally distributed, the fibrous sheet material 10bs (see FIG. 4) may have the same configuration. The fibrous sheet material 10bs, in which a plurality of thermally fused portions are distributed three-dimensionally, can be produced by subjecting a fibrous web or nonwoven fabric formed mainly from thermoplastic fibers to a heat treatment such as hot air treatment.

Examples of non-absorbent synthetic polymers (thermoplastic polymers) preferably used as the material of the constituent fibers 11F of the fibrous cluster 11 include: polyolefins such as polyethylene and polypropylene; polyesters, for example, polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid, alkyl polymethacrylate, polyvinyl chloride and polyvinylidene chloride. They can be used alone or in combination of two or more polymers. The 11F fiber may be a monofilament made from one type of synthetic resin (thermoplastic resin) or a blend of resins in which two or more types of synthetic resins are mixed, or may be a composite fiber. As used herein, composite fiber refers to a synthetic fiber (thermoplastic fiber) obtained by joining and spinning two or more types of synthetic resins from different components using a spinneret; where a composite fiber having a structure in which a plurality of components are spun continuously in the longitudinal direction of the fiber and connected to each other in a single fiber. The composite fiber may be in the sheath-core form or in the form of contiguous fibers, and there is no particular limitation on the form of the composite fiber.

The absorbent fiber 12F can be any absorbent fiber commonly used as a material for forming an absorbent member for use in this type of absorbent article. Examples include: natural fibers, including wood pulp, for example, softwood pulp and hardwood pulp, and non-wood pulp, for example, cotton pulp and hemp pulp; and modified pulps such as cationized pulp and mercerized pulp. These fibers may be used alone or in combination of two or more components. Of the general list of absorbent fibers, cellulose absorbent fiber is particularly preferred for use.

In the absorbent body 10, there is no particular limitation on the weight ratio of the fibrous clusters 11 and the absorbent fibers 12F included therein, and the weight ratio can be adjusted as required according to the specific application of the absorbent body 10, the type of constituent part of the fibers 11F of the fiber cluster 11, the type of absorbent 12F fibers and other conditions. However, in view of reliably exhibiting the effects of the present invention, the weight ratio of the 11 fiber clusters and the 12F absorbent fibers included in the cluster is preferably: 11 fiber clusters/12F absorbent fibers from 20/80 to 80/20, and more preferably, from 40/60 to 60/40.

The mass amount of fiber clusters 11 included in the absorbent member 10 is preferably 20% by mass or more, and more preferably 40% by mass or more, and preferably 80% by mass or less, and more preferably 60% by mass. or less based on the total dry weight of the absorbent 10.

The amount of 12F absorbent fibers included in the absorbent member 10 is preferably 20 mass% or more, and more preferably 40 mass% or more, and preferably 80 mass% or less, and more preferably 60 mass% or less than the total weight of the absorbent element 10 in a dry state.

The basis weight of the fibrous cluster 11 of the absorbent member 10 is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and preferably 640 g/m ² or less, and more preferably 480 g/m ² or less.

The base weight of the 12F absorbent fibers in the absorbent body 10 is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and preferably 640 g/m ² or less, and more preferably 480 g/m ² or less.

The absorbent element 10 may contain a component other than the fibrous clusters 11 or absorbent fibers 12F. The component other than the fibrous cluster 11 or the absorbent fiber 12F may be, for example, an absorbent polymer. As the absorbent polymer, a particulate absorbent polymer is usually used, or alternatively, an absorbent polymer in the form of fibers can be used. In case the superabsorbent polymer is used in the form of particles, the shape can be any: spherical, in the form of a cluster, in the form of a round bale and indefinite. The average particle size of the absorbent polymer is preferably 10 µm or more, and more preferably 100 µm or more, and preferably 1000 µm or less, and more preferably 800 µm or less. As the absorbent polymer, an acrylic acid polymer or copolymer or an alkali metal salt of acrylic acid can be generally used. Examples thereof include polyacrylic acid and its salts; and polymethacrylic acid and its salts.

The amount of the absorbent polymer contained in the absorbent member 10 is preferably 5 mass% or more, more preferably 10 mass% or more, and preferably 60 mass% or less, and more preferably 40 mass% or less, from the total weight of the absorbent element 10 in a dry state.

The basis weight of the absorbent polymer in the absorbent body 10 is preferably 10 g/m ² or more, and more preferably 30 g/m ² or more, and preferably 100 g/m ² or less, and more preferably 70 g/m ² or less.

The weight of the absorbent body 10 can be adjusted as required according to the specific application of the absorbent body 10. For example, when using the absorbent body 10 as the absorbent of an absorbent article such as a disposable diaper or sanitary napkin, the weight of the absorbent body 10 is preferably 100 g/ m ² or more, and more preferably 200 g/m ² or more, and preferably 800 g/m ² or less, and more preferably 600 g/m ² or less.

The absorbent body 10 having the configuration described above has a very high flexibility and a very high resilience, it also has a very high resilience after compression, it can quickly deform in response to an external force, and can quickly return to its original state after the external force is removed. . The absorbent member properties described above can be evaluated by using compression workload (WC) and compression recovery rate (RC) as measurement metrics. Compressive workload is a measure of the resilience of an absorbent. The larger the WC value, the greater the elasticity. The compression recovery rate is a measurement indicating the degree of recovery after an absorbent body is compressed and then released from compression. The larger the RC value, the greater the resilience after compression. Also, when considering the liquid absorption parameters and the retention function of the absorbent member 10, the WC value and the RC value should preferably be high not only when the absorbent member 10 is in a dry state, but also when the absorbent member 10 is in a wet state due to liquid absorption. emitted by a person, or in similar situations. In order for the absorbent member 10 to have such properties when it is wet, it is effective to use non-absorbent fibers such as thermoplastic fibers as part of the fibers 11F of the fiber cluster 11 as described above.

How to Measure Compression Workload (WC) and Compression Recovery Rate (RC)

It is widely known that the compression workload (WC) and the compression recovery rate (RC) of the absorbent body 10 can be represented by the desired values obtained using the SOC (SOC - Kawabata Rating System) available from Kato Tech Co., Ltd. . (Reference Document: Standardization and Analysis of the Evaluation Structure (Second Edition) written by Sueo Kawabata, published July 10, 1980). Specifically, compression workload and compression recovery rate can be measured using an automatic compression testing machine COK-FB3 AUTO-A available from Kato Tech Co., Ltd.

Measurement technique

Take a sample having a quadrangular shape with dimensions of 195 mm × 68 mm in plan view (absorbent body not wrapped in a core wrapping web; i.e., absorbent core) and attach it to the test table of the machine for testing compression. The sample is then pressed between steel plates having an area of 2 cm ² and a round flat front surface. The compression speed is 0.01 cm/s and the maximum compression load is 490.2 mN/cm ² . During the recovery process, the measurement is also carried out at the same speed. Compression workload (WC) is represented by the following equation. In the equation: T _m - thickness under load 490.2 mN/cm ² (4.9 kPa); T _o - thickness under load 4,902 mN/cm ² (49 Pa); P is the load during the measurement (mN/cm ² ).

Also, the compression recovery rate (RC) is the ratio between the compression workload (WC) when the sample was compressed and the compression workload (WC') when the sample after compression is restored from the compressed state to the original state, and is therefore represented by [ WC'/WC] × 100.

Equation 1

When walking a consumer wearing an absorbent article into which the absorbent 10 configured as described above is inserted, the absorbent 10 twists and deforms in response to an external force applied by the wearer's two hips, and also quickly returns to its original state when removed. external force. Such absorbent member properties can be evaluated with torque as a measure. Since the torque value of the absorbent article measured using the following technique is small, it can be determined that the absorbent member can be more easily twisted and deformed, and it is unlikely that wrinkles will be generated even when it is inserted into the absorbent article, and therefore , a good fit can be achieved by using an absorbent article. Also, for the same reason regarding the WC and RC values as described above, it is preferable that the absorbent body 10 can be easily twisted and deformed regardless of whether the absorbent body 10 is in a dry state or a wet state.

The absorbent article comprising the absorbent body 10 in a dry state has a torque of preferably 0.20 mNm or more, and more preferably 0.30 mNm or more, and preferably 1.30 mNm or less, and more preferably 0 .80 mNm or less.

The absorbent article comprising the absorbent body 10 in the wet state has a torque of preferably 0.20 mNm or more, and more preferably 0.30 mNm or more, and preferably 1.20 mNm or less, and more preferably 0 .80 mNm or less.

Torque measurement method

The torque tester shown in FIG. 2 in JIS K 7244-2 (JIS - Japanese Industrial Standard). However, when considering the measurement conditions, in particular, the shape and dimensions of the sample, the shape and dimensions of the sample recommended in JIS K 7244-2 are not suitable for this case, since the measurements in this case are carried out on the assumption that the absorbent should be used in absorbent product. Instead, use the shape and dimensions of the sample that meet the requirements for accepting the terms of use of the absorbent element in the absorbent article. Specifically, as a sample (absorbent member in dry state or wet state), a floor consisting of a top sheet and an absorbent member is provided. The deck has dimensions of 120 mm × 70 mm and is rectangular in plan view. As a floor, for example, a floor of an absorbent member and a member located on the side facing the skin of the wearer relative to the absorbent member can be used when the absorbent article is worn, and such a floor can be separated from the commercially available absorbent article. In the event that an additional element (eg, an element called "substrate") is provided between the absorbent element and the topsheet, then the floor containing the additional element is used as a sample. For measurement, the thickness of the sample can be arbitrarily chosen, but preferably it is from 1 mm to 10 mm. The sample is fixed at both its longitudinal ends in the upper and lower clamps of the measuring instrument. The sample is twisted by turning both ends in opposite directions by 5 degrees relative to the longitudinal direction of the sample as the axis of rotation, and the maximum amount of torque applied to the sample is taken as the desired value. During the measurement, a weight of 62 g is used as a balance load, as shown in FIG. 2 in JIS K 7244-2, and thus a measurement under tension of 62 gram-force in the longitudinal direction of the specimen is carried out. The distance between the clamps is set equal to 100 mm in the absence of tension.

At this time, a "dry absorbent body" which is a measurement sample in the above measurement procedure is provided, leaving the floor as a measurement sample to age in an environment at a temperature of 23°C and a relative humidity of 50% for 24 hours. The "wet absorbent body", which is the reference for measurement according to the above measurement procedure, is provided as follows: the dry deck is laid horizontally with its topsheet side (the side facing the consumer's skin) facing up; an acrylic plate with a cylinder is applied to the top sheet, containing a hole for pouring liquid with a diameter of 1 cm at the bottom; 5.0 g of defibrinated horse blood is poured through the hole; and the resulting state is maintained for one minute after the spill of the fluid, defibrinated horse blood. The defibrinated horse blood for shedding into the floor as a measurement sample is defibrinated horse blood, available commercially from Nippon Bio-Test Laboratories Inc., and has a controlled viscosity of 8 centipoise at a liquid temperature of 25°C. Viscosity is the viscosity measured using a TVB-10M viscometer, available from Toki Sangyo Co., Ltd, with an L/Adp rotor (rotor code 19) at a rotation speed of 30 rpm. Also, when measuring, the corresponding parts of the measuring instrument up to the place on the deck on which the defibrinated horse blood is shed and the peripheral part thereof is covered with a piece of plastic wrap (Saran Specialty Wrap is a registered trademark) commercially available from Asahi Kasei Corporation, cut to size 4 cm × 4 cm, to prevent wetting of the measuring instrument.

The absorbent element according to the present invention is preferably used as an element constituting an article to form an absorbent article. When the term "absorbent article" is used in this specification, this term broadly covers articles used to absorb liquids excreted by the human (human body) (for example: urine, soft feces, menstrual blood and sweat), including so-called open-type disposable diapers with attached tape, pant-type disposable diapers, sanitary napkins, pairs of sanitary panties and urological pads. An absorbent body used in an absorbent article generally comprises a liquid-absorbing core and a liquid-pervious core wrapping web that covers the outer surface of the absorbent core. An absorbent member according to the present invention can be used as an absorbent core. As the wrapping web of the core part, paper, non-woven fabric or the like can be used. The absorbent member 10 does not necessarily comprise a core wrapping web, in which case the absorbent core itself is used as the absorbent member 10 in an absorbent article.

An absorbent article comprising an absorbent according to the present invention typically comprises: a liquid-pervious topsheet that can be brought into contact with a wearer's skin when the absorbent article is worn; a liquid-impervious or moisture-repellent backsheet; and a liquid-retaining absorbent member provided between the topsheet and the backsheet. Any of various types of nonwoven fabrics or porous synthetic resin webs can be used as the topsheet. As the backsheet, a synthetic resin film made of polyethylene, polypropylene, polyvinyl chloride or the like, or a composite material of such a synthetic resin film and a non-woven fabric, can be used. The absorbent article may further comprise various types of elements according to the particular application of the absorbent article. Such elements are known to those skilled in the art. For example, in the event that the absorbent article is to be applied to a disposable diaper or sanitary napkin, one or more vapor-resistant barrier materials may be provided on the right and left sides of the top sheet.

Next, the manufacturing method of the absorbent member according to the present invention will be described with reference to the drawings based on the manufacturing method of the absorbent member 10 described above. In FIG. 6 shows the general configuration of the manufacturing apparatus 1 (fiber spreading apparatus) of the absorbent member 10. The manufacturing apparatus 1 comprises a rotating drum 2 in which an accumulation recess 22 is formed in the outer circumferential surface 2f of the drum, and a tube 3 containing an inner flow passage 30 for conveying the raw material of the absorbent member 10 to the outer circumferential surface 2f. The manufacturing apparatus 1 is configured such that the raw material is laid in the storage recess 22 as the rotary drum 2 rotates about the rotation axis along the circumferential direction 2Y of the drum, where the raw material is conveyed by an air flow (air suction) generated in the flow path 30 by the suction air from inside the rotary drum 2. The first feeder 4 and the second feeder 5 are connected to the pipe 3 as feeders for supplying the raw material (fibrous material) of the absorbent member 10. Under the rotary drum 2, a conveyor 6 with an air suction system is provided, where the conveyor 6 with the air suction system is designed to receive the layered fibrous material (layered raw material) released from the storage recess 22, i. e. absorbent element 10, and for transporting the obtained absorbent element 10 to the next stage. On the side opposite the pipe 3, across the width of the rotating drum 2, a press belt 7 is provided for pressing the webbed fibrous material into the accumulating recess 22, where the press belt 7 is pulled along the outer circumferential surface 2f of the rotating drum 2. The press belt 7 is endless and breathable or an airtight tape that wraps around shaft 71 and shaft 72 and is pulled through by the rotation of the rotating drum 2.

The rotary drum 2 includes a main body 20 of a cylindrical drum, which is a metal rigid body, and an outer peripheral element 21 overlapped relative to the outer peripheral part of the main drum body 20 and provides an outer peripheral surface 2f of the rotary drum 2. The outer peripheral element 21 receives a driving force from a source energy, for example, a motor, and rotates about the horizontal axis of rotation in the direction R1 along the circumferential direction of the drum. However, the drum main body 20 provided on the inside of the outer peripheral member 21 is fixed and thus does not rotate. The two opposite ends of the drum main body 20 in the drum width direction (each) are hermetically sealed with a side wall and a sealing member such as felt (not shown in the drawings).

The outer peripheral member 21 comprises a breathable porous plate 23 constituting the bottom portion of the storage recess 22 (i.e., the fiber deposition surface) and a less breathable or airtight patterning plate 24 that constitutes a portion other than the fiber deposition surface during outer circumferential surface 2f of the rotary drum 2. In the manufacturing apparatus 1, the pattern plate 24 has an annular shape and extends continuously along the entire length of the circumferential direction 2Y of the drum. The pair of pattern plates 24 and 24 are disposed on opposite edge portions in the direction of the rotation axis of the rotary drum 2, and a porous plate 23 is provided between the pair of pattern plates 24 and 24.

The porous plate 23 is an air-permeable plate that passes the airflow generated by sucking the air from the inside of the apparatus (the inside of the rotary drum 2) from the outside of the apparatus (the outer side of the rotary drum 2), whereby the raw material supplied by the airflow is held thereon without being able to the passage of the raw material through it, but allowing only air to pass through it. A plurality of air suction holes passing through the porous plate 23 in the thickness direction are formed over the entire porous plate 23, and the air suction holes function as holes allowing air flow through it when the storage recess 22 passes over the space where inside rotating drum 2 is maintained at a negative pressure. As the porous plate 23, for example, a mesh plate made of a metal or a resin, or a metal or a resin plate in which a plurality of pores are formed by etching or punching or the like can be used. As the pattern plate 24, for example, a metal plate made of stainless steel or aluminum, a resin plate, or the like could be used.

As shown in FIG. 6, the interior of the drum main body 20 is divided into a plurality of spaces A, B, and C in the drum circumferential direction 2Y. A pressure reducing mechanism (not shown) by which the internal pressure is reduced is connected to the drum main body 20 . The pressure reducing mechanism includes an air exhaust pipe (not shown) connected to a side wall (not shown) of the drum main body 20, and an air exhaust fan (not shown) connected to the air exhaust pipe. The plurality of spaces A, B, and C in the drum main body 20 are independent of each other, and the negative pressure (suction forces) in the plurality of spaces can be independently controlled by the pressure reduction mechanism.

In the rotary drum 2, a predetermined area in the circumferential direction 2Y of the drum (specifically, in the space A, the outer circumferential part of which is covered by the tube 3), is a fiber spreading area, in which the fiber as a raw material can be spread due to the suction of air from its inner side. By rotating the outer peripheral member 21 about the rotation axis and maintaining a negative pressure in space A, the negative pressure in space A acts on the bottom (porous plate 23) of the storage recess 22, thereby sucking air through the plurality of air suction holes formed in the bottom part, while the storage recess 22 formed in the outer circumferential member 21 extends over the space A. By sucking air through the air suction holes, the raw material conveyed through the supply path 32 of the pipe 3 is guided to the storage recess 22 and is laid on the lower part of the storage recess 22. On the other hand, the pressure in the space B of the rotary drum 2 is usually set to a negative pressure less than that of the spaces A or zero pressure (atmospheric pressure), and the pressure in the space C is set are at zero pressure or positive pressure since space C is an area containing a zone for transferring the layered fibrous material in the storage recess 22 and its front and rear zones.

The air suction conveyor 6 comprises an endless breathable belt 63 wrapping around the drive shaft 61 and the driven shaft 62, and the suction chamber 64 located in the opposite area where the breathable belt 63 is located between the space C of the rotary drum 2 and the suction chamber 64. the core wrapping web 10W is supplied to the breathable tape 63, and the layered fibrous material used as the absorbent 10 released from the storage recess 22 is transferred to the core wrapping wrapping web 10W.

As shown in FIG. 6, the pipe 3 extends continuously over the rotary drum 2 from the first feeder 4, and has an upstream opening and a downstream opening (side opening of the rotary drum 2) in the feed direction of the raw material. The flow channel 30 for conveying the raw material extends between the upstream opening and the downstream opening. A spray tube 31 for supplying the absorbent resin particles to the flow channel 30 is provided in the top plate of the tube 3. In the case where the absorbent resin particles are to be contained in the absorbent member 10, the resin spray tube 31 is used.

The absorbent element 10 described above contains two types of fibrous material, i. fibrous clusters 11; and absorbent fibers 12F. Accordingly, the manufacturing apparatus 1 comprises a first feeder 4 (manufacturing apparatus for absorbent fibers) through which the absorbent fibers 12F are fed into the tube 3, and a second feeder 5 (fiber cluster making apparatus) through which the fiber clusters 11 are supplied. into pipe 3, in the form of a mechanism for supplying fibrous material.

The first feed mechanism 4 is located near the opening, on the opposite side of the tube 3 with respect to the rotating drum 2. The first feed mechanism 4 has the same configuration as the fiber material feed mechanism of the fiber spreader, for this type of pulp or similar fiber, and includes a defibrillating machine 40 for defibrillating the strip-like fibrous sheet material 10as in which a plurality of absorbent fibers 12F are accumulated.

In FIG. 7 is a schematic, enlarged view of the second feeder 5. The second feeder 5 is an apparatus for producing and feeding cuboid-shaped fiber clusters 11, such as the fiber cluster 11A shown in FIG. 3(a) and the machine performs the step of cutting in strips the fibrous sheet material 10bs made from the constituent fibers 11F for the fiber cluster 11 of predetermined dimensions in two directions (first direction D1 and second direction D2) intersecting each other. , as shown in FIG. 4. The second feed mechanism 5 includes a first cutting shaft 53 for cutting the material to be cut (fiber sheet material 10bs) in the first direction D1; a second cutting shaft 54 for cutting the material to be cut in the second direction D2; and a take-up shaft 55 provided between two shafts 53 and 54. The three shafts 53, 54 and 55 are rotatable in opposite directions relative to each other, where their outer peripheral surfaces face each other while their rotation axes are parallel. Cutting blades 51 and 52 are respectively provided on the outer circumferential surfaces of the cutter shafts 53 and 54, while there are no cutting blades on the outer circumferential surface of the take-up shaft 55. Thus, the outer circumferential surface of the take-up shaft 55 is smooth. Near the outer circumferential surface of the take-up shaft 55 are: the guide shaft 56, the first cutting shaft 53, the guide shaft 57 and the second cutting shaft 54 in this order from the upstream side in the direction of rotation.

The “first direction D1”, which is one of the cutting directions of the fibrous sheet material 10bs, corresponds to the conveying direction MD (machine direction) of the fibrous sheet material 10bs in the second feed mechanism 5, and the angle formed between the first direction D1 and the transport direction MD is less than 45 degrees. In the embodiment shown in the diagram, the first direction D1 and the transport direction MD coincide with each other, and the angle formed between the first direction D1 and the transport direction MD is zero.

Similarly, the "second direction D2", which is another one of the cutting directions of the fibrous sheet material 10bs, corresponds to a direction intersecting the first direction D1. In the embodiment shown in the diagram, the first direction D1 (transport direction MD) and the second direction D2 are at right angles to each other, and the angle formed between the directions D1 and D2 is 90 degrees.

Also, the direction indicated by the position CD (CD - Cross direction - the transverse direction of the material - the machine. - Approx. Translator) in Fig. 6 is a direction at right angles to the conveying direction MD, and it is parallel to the rotation axis of the rotary drum 2 and the axes of the various shafts of the manufacturing apparatus 1. In the embodiment shown in the diagram, the CD direction is the same as the width direction (a direction at right angles to the longitudinal direction) of the absorbent member 10 being longitudinally laminated in a strip like the fibrous webs of materials 10as and 10bs, each in the form of a longitudinal strip.

As shown in FIG. 6 and 7, on the outer circumferential surface of the first cutting shaft 53, a plurality of cutting blades 51 are provided in the circumferential direction of the shaft 53 (in the first direction D1) at a predetermined interval in the axial rotation direction of the shaft 53, i. in direction CD (second direction D2).

On the outer circumferential surface of the second cutting shaft 54, a plurality of cutting blades 52 are disposed in the direction of the axis of rotation of the shaft 54, i. in the direction CD (in the second direction D2), at a predetermined interval in the circumferential direction of the shaft 54, i. e. in the transport direction MD (in the first direction D1).

The method for manufacturing the absorbent body 10 using the manufacturing apparatus 1 configured as described above is basically a known method for manufacturing an absorbent body using a fiber spreading apparatus having a similar configuration. Specifically, as shown in FIG. 6, the laid fibrous material is obtained in the following way: absorbent fibers 12F obtained by defibrillating the fibrous sheet material 10 while transporting the fiber from the first feeder 4 to the rotary drum 2 using the air flow (air suction) generated in the flow channel 30 of the pipe 3 by suction air from inside the rotary drum 2, while rotating the rotary drum 2 in the direction R1 about the axis of rotation along the circumferential direction 2Y of the drum, and the fibers are thus laid in the storage recess 22 in the area where the space A is provided. the member 10 in the storage recess 22 passes through the region where space A is provided (part of the outer circumferential surface 2f of the rotary drum 2 covered by the tube 3) when the outer circumferential member 21 rotates, where the absorbent member 10 is pressed by the press with a webbing belt 7 while feeding the absorbent 10 to the area where the space B is provided, and transported by bringing it closer to the conveyor 6 with the suction system. Thereafter, the absorbent member 10 is released from the storage recess 22 to be transferred to the core wrapping web 10W fed to the suction conveyor 6, and the absorbent member 10 is then covered with the core wrapping web 10W.

The method for manufacturing the absorbent body 10 is characterized in that it further includes, in addition to the basic steps described above, the step of manufacturing and supplying the fiber clusters 11 to the second feeder 5. Specifically, as shown in FIG. 6 and 7, the main feature of the method for manufacturing the absorbent body 10 is that it includes: the step of cutting the fibrous sheet material 10bs into a strip, in which a plurality of fibers 11F are accumulated in a first direction D1 (transport direction MD) extending along the longitudinal direction of the fibrous sheet of the material 10bs so as to obtain a plurality of narrow webs 10bt in the form of strips, and then each of the plurality of narrow webs 10bt is cut in the second direction D2 (direction CD) intersecting with the first direction D1 (located at right angles to the first direction D1 in the embodiment shown in the diagram) so that fibrous clusters 11 are formed; and the step of mixing the fibrous clusters 11 thus obtained with the absorbent fibers 12F provided separately.

In the second feed mechanism 5, the strip-like fibrous sheet material 10bs is first cut in the first direction D1, which is the longitudinal direction of the web 10bs and is also the conveying direction MD between the first cutting roll 53 and the take-up roll 55, so as to produce a plurality of narrow webs 10bt, extending in the direction D1, and a plurality of narrow blades 10bt in the form of strips, then cut in the second direction D2, which is the width direction (direction CD) located at right angles to the longitudinal direction of the narrow blades 10bt, between the take-up roll 55 and the second cutting roll 54 ( cutting step). By cutting the fibrous sheet material 10bs into strips successively in the first direction D1 and in the second direction D2 at right angles to the first direction D1 in this manner, the fibrous sheet material 10bs is cut into so-called "cubes" as shown in FIG. 4, and thus a plurality of fibrous clusters 11 are obtained. The outer shape of the main body portion 110 of each of the plurality of fibrous clusters 11 produced by the above-described method has the shape of a cuboid as shown in FIG. 3(a).

A plurality of fibrous clusters 11 made by cutting the fibrous sheet material 10bs are fed to the flow path 30 of the pipe 3 through the suction nozzle 58, and mixed with the absorbent fibers 12F dispersed in the flow path 30 by the first feed mechanism 4 to the rotary drum 2, and laid in the storage recess 22 together with the absorbent fibers 12F (mixing step). The suction nozzle 58 has an opening at each of its two opposite longitudinal ends. The hole 581, which is one of the holes, is located near the place where the second cutting shaft 54 and the take-up shaft 55 are closest to each other, and the suction nozzle 58 is in communication with the flow channel 30 of the pipe 3 through another hole (not shown). The plurality of fibrous clusters 11 produced between the second cutting shaft 54 and the take-up shaft 55 are sucked into the suction nozzle 58 through the opening 581 and fed into the pipe 3. mechanism 4 and closer to the rotating drum 2 relative to the resin spray tube 31, as shown in FIG. 6.

Above, the present invention has been described with reference to an embodiment according to the present invention. However, the present invention is not limited thereto, and can be modified as required.

For example, in an absorbent element according to the present invention, the fibrous clusters need not be uniformly distributed throughout the absorbent element, but may be unevenly distributed. The absorbent member in the exemplary embodiment in which the fibrous clusters are unevenly distributed may be an absorbent member comprising a web structure consisting of a layer containing primarily fibrous clusters and a layer containing primarily absorbent fibers.

Also, all fibrous clusters (synthetic fiber wads) in the absorbent body of the present invention are not necessarily shaped fibrous boluses like the fibrous clusters 11. a certain form, without departing from the essence of the present invention. With respect to an embodiment of the present invention, the following additional statements are also disclosed.

1. Absorbent element containing:

many fibrous clusters containing synthetic fibers; and

many absorbent fibers;

where the fibrous clusters are intertwined with each other or the fibrous clusters and absorbent fibers are intertwined;

each of the fibrous clusters contains two opposite base surfaces and a body surface that connects the two base surfaces; and

the number of fiber ends per unit area of the body surface is greater than the number of fiber ends per unit area of each of the base surfaces.

2. The absorbent element according to claim 1,

in which the total area of the two base surfaces is greater than the total surface area of the body.

3. Absorbent element according to claim 1 or 2,

in which each of the fibrous clusters contains a protruding part of the fibrous bundle, protruding outward from the surface of the body and containing a plurality of fibers.

4. Absorbent element according to paragraph 3,

in which the protruding part of the fibrous bundle contains a thermally fused part in which a plurality of fibers are thermally fused to each other.

5. Absorbent element according to paragraph 3 or 4,

in which each of the fibrous clusters contains the main part of the body, defined by the base surfaces and the surface of the body, and

the protrusion length of the protruding part of the fibrous bundle from the main part of the body, preferably the protrusion length of the protruding part of the fibrous bundle from the body surface is 0.2 mm or more and 7 mm or less, preferably 0.5 mm or more and 4 mm or less.

6. Absorbent element according to any one of paragraphs 1-5,

wherein the outer shape of each of the fibrous clusters is cuboid or disk shaped.

7. Absorbent element according to any one of paragraphs 1-6,

wherein each of the base surfaces is rectangular in plan view and the short side of the rectangle is less than the thickness of the absorbent member.

8. Absorbent element according to paragraph 7,

in which the ratio of the length of the short side of each of the base surfaces to the thickness of the absorbent element, (largest/smallest) is from 0.08 or more to 0.5 or less.

9. Absorbent element according to paragraph 7 or 8,

wherein the short side length of each of the base surfaces is 0.3 mm or more to 10.0 mm or less, preferably 0.5 mm or more to 6.0 mm or less.

10. Absorbent element according to any one of paragraphs 7-9,

wherein the long side length of each of the base surfaces is 0.3 mm or more to 30.0 mm or less, preferably 2.0 mm or more to 15.0 mm or less.

11. Absorbent element according to any one of paragraphs 1-10,

where, in the projected views in two directions of the absorbent element, located at right angles to each other, there are superimposed parts of a plurality of fibrous clusters in an arbitrary unit area of 10 mm ² .

12. Absorbent element according to any one of paragraphs 1-11,

in which each of the fibrous clusters contains a plurality of thermoplastic fibers (synthetic fibers) and has a three-dimensional structure in which a plurality of thermoplastic fibers are thermally fused to each other.

13. Absorbent element according to any one of paragraphs 1-12,

in which the ratio of the masses of fibrous clusters and absorbent fibers included in its composition (highest/lowest) is from 20/80 to 80/20.

14. Absorbent element according to any one of paragraphs 1-13,

wherein some fibrous clusters are entangled with other fibrous clusters or absorbent fibers and some fibrous clusters are entangled with other fibrous clusters or absorbent fibers.

15. Absorbent element according to paragraph 14,

wherein the total amount of entangled fibrous clusters and entanglement fibrous clusters is preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, of the total number of fibrous clusters in absorbent element.

16. Absorbent element according to any one of paragraphs 1-15,

wherein the amount of fibrous clusters having parts for bonding with other fiber clusters or absorbent fibers by fiber entangling is preferably 70% or more, more preferably 80% or more, of the total number of fibrous clusters having parts for bonding with other fiber clusters or absorbent fibres.

17. Absorbent element according to any one of paragraphs 1-16,

in which the fibrous clusters are obtained from a non-woven material.

18. Absorbent element according to any one of paragraphs 1-17,

in which the ratio (N ₁ /N ₂ ) of the number of N ₁ fiber ends per unit area on the base surfaces to the number of N ₂ fiber ends per unit area of the body surface is 0 or more and 0.90 or less, preferably 0.05 or more and 0.60 or less.

19. Absorbent element according to any one of paragraphs 1-18,

wherein the number of end portions of fibers 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, preferably - 3, end portions of the fibers / mm ² or more and 6, the end portions of the fibers / mm ² or less.

20. Absorbent element according to any one of paragraphs 1-19,

wherein the number of end portions of the fibers per unit body surface area is 5 end portions of the fibers / mm ² or more and 50 the end portions of the fibers / mm ² or less, preferably - 8 the end portions of the fibers / mm ² or more, and more preferably - 40 end parts of fibers/mm ² or less.

21. Absorbent element containing:

many fibrous clusters containing synthetic fibers; and

many absorbent fibers

in which the fibrous clusters are entangled with each other or are entangled with fibrous clusters and absorbent fibres,

where each of the fibrous clusters contains two opposite base surfaces and a body surface that connects the two base surfaces, and

each of the fibrous clusters contains a protruding part of the fibrous bundle protruding outward from the surface of the body and containing a plurality of fibers.

22. Absorbent element according to paragraph 21,

in which the total area of the two base surfaces is greater than the total surface area of the body.

23. An absorbent article comprising an absorbent according to any one of paragraphs 1-22.

24. Absorbent article according to paragraph 23,

wherein the absorbent article in the dry state has a torque of 0.20 mNm or more and 1.30 mNm or less, preferably 0.30 mNm or more and 0.80 mNm or less.

25. Absorbent article according to paragraph 23 or 24,

wherein the absorbent article when wet has a torque of 0.20 mNm or more and 1.20 mNm or less, preferably 0.30 mNm or more and 0.80 mNm or less.

Examples

Hereinafter, the present invention is described in more detail with reference to examples, but the present invention is not limited to them.

Examples 1-4

The absorbent members were manufactured according to the manufacturing method described above using an absorbent member manufacturing apparatus having the same configuration as the manufacturing apparatus 1 shown in FIG. 6. As a fibrous sheet material for obtaining fibrous clusters, a breathable non-woven fabric was used, which contained, as its constituent fibers, a hydrophobic thermoplastic fiber (non-absorbent fiber with a diameter of 18 μm) made of polyethylene polymer and polyethylene terephthalate polymer and had a basis weight of 21 g/m ² (fibrous web containing thermally fused parts of the constituent fibers). Bleached softwood kraft pulp (NBKP) with a fiber diameter of 22 µm was used as absorbent fibers. The fibrous clusters (lumps of synthetic fibers of a certain shape) used in the absorbent body (each) comprised a main body part in the form of a cuboid, as shown in FIG. 3(a). The base surface 111, which was rectangular in plan view, had a short side 111a of 0.8 mm and a long side 111b of 3.9 mm, and the fiber clusters had a thickness T of 0.6 mm. Also the number of end portions of fibers per unit area of the base surface 111 of the end portion was 3.2 fibers / mm ^2, and the number of end portions of the fibers per unit of surface area of the body 112 was 19.2 end portions of the fibers / mm ^2.

Comparative Example 1

In Comparative Example 1, the absorbent of a commercially available sanitary napkin (product name: Tanom Pew Slim 23 cm; commercially available from Unicharm Corporation) was used as the absorbent. The absorbent body of Comparative Example 1 was made from a mixture of synthetic fibers and cellulose fibers (absorbent fibers) and did not contain any fibrous clusters.

Comparative Example 2

The absorbent body 1 was made in the same manner as in Examples 1-4, except that small pieces of nonwoven material of indefinite shape were used as fiber clusters, and that the absorbent body was treated with hot air to thermally fuse each other. other small pieces of nonwoven material in the absorbent element. In the hot air treatment of the absorbent body, a mixed accumulation (length 210 mm×width 66 mm) of small pieces of nonwoven material and fibrous mass was left to age in an electric dryer (for example, commercially available from Isuzu Seisakusho, Co., Ltd.) at a temperature 140°C for 30 minutes to heat-fuse small pieces of non-woven fabric with each other. The indefinitely shaped small pieces of nonwoven fabric used in this example were made by tearing a breathable nonwoven fabric, the same as in Examples 1-4, in an arbitrary direction, and the small pieces of nonwoven fabric had a total length of about 25 mm in plan view. .

Performance evaluation

For each of the absorbent members made in the Examples and Comparative Examples, the dry compression workload (d-WC), the wet compression workload (w-WC), the recovery rate after dry compression were determined according to the methods described above. condition (d-RC), wet compression recovery rate (w-RC), dry torque and wet torque. The results are shown in Table 1 below.

The torque was measured on an absorbent body covered on one side by a top sheet, which was considered to be an absorbent article. The characteristics of the upper sheet used in the measurements were as follows.

Example other than Comparative Example 1: A breathable nonwoven fabric formed from fibers made from polyethylene resin and polyethylene terephthalate resin, and having a base weight of 74 g/m ² and a thickness of 1.4 mm.

Comparative Example 1: A topsheet (with a base weight of 27 g/m ² ) of a sanitary napkin (product name: Tanom Pew Slim 23 cm) available from Unicharm Corporation.

Table 1

Example Comparative Example one 2 3 4 one 2 Fibrous clusters Yes Yes Yes Yes Not Yes Method for bonding fibrous clusters entanglement entanglement entanglement entanglement - thermal fusion The proportion of fibrous clusters (wt.%) 25 50 50 75 50 Fiber Cluster Dimensions (mm) 0.8×3.9 0.8×3.9 0.8×3.9 0.8×3.9 - 25 ^*1 Fiber Cluster Base Weight (g/m ² ) 50 one hundred one hundred 150 116 ^*2 one hundred Absorbent fiber base weight (g/m ² ) 150 one hundred one hundred 50 116 one hundred Absorbent resin base weight (g/m ² ) 0 0 50 0 35 0 Absorbent thickness (mm) 2.8 2.8 2.8 2.8 2.8 2.8 Absorbent element when dry d-WC
(mN cm/cm ² ) 32.84 36.76 35.78 39.22 19.12 24.02 d-RC (%) 43 45 47 50 40 52 Absorbent pad when wet w-WC
(mN cm/cm ² ) 29.41 32.35 31.37 36.27 15.20 19.61 w-RC (%) 40 42 43 48 25 47 Torque
(mN m) Stack containing an absorbent in a dry state 0.52 0.44 0.48 0.42 0.55 1.25 A stack containing an absorbent in a wet state 0.64 0.55 0.60 0.50 0.84 1.45

*1 - Total length of fiber cluster

*2 - Weight of the synthetic fiber backing contained in the absorbent since the absorbent did not contain fibrous clusters

As shown in Table 1, the absorbent members made in the Examples contained fibrous clusters that were "shaped fibrous bolls" where each was defined by two reference surfaces and a body surface intersecting the two reference surfaces. For this reason, in both the dry state and the wet state, the compression workload was larger and the torque of the absorbent article was less than that of Comparative Examples 1 and 2, which did not contain shaped fibrous clusters. As can be seen from the above facts, the absorbent member containing the fibrous cluster having the specific shape described above was flexible, had a very high resilience and a very large resilience after compression, and could be deformed with a good response to an external force, and thus, the absorbent could provide improved wearing comfort and perform better when used in an absorbent article.

Applicability in industry

The absorbent body of the present invention has a very high resilience and a very high resilience, is elastically deformable in response to an external force, and can provide improved wearing comfort and better fit when used in an absorbent article.

Also, the absorbent article according to the present invention contains a high quality absorbent member and thus can provide a very high degree of wearing comfort and a very high fit.

Claims (25)

1. Absorbent element containing many fibrous clusters containing synthetic fibers, and many absorbent fibers; in which the fibrous clusters are intertwined with each other or the fibrous clusters and absorbent fibers are interchanged; in which each of the fibrous clusters contains two opposite base surfaces and a body surface that connects the two base surfaces; and the number of fiber ends per unit area of the body surface is greater than the number of fiber ends per unit area of each of the base surfaces. 2. An absorbent body according to claim 1, wherein the total area of the two base surfaces is greater than the total surface area of the body. 3. An absorbent member as claimed in claim 1, wherein each of the fibrous clusters comprises a protruding portion of a fibrous tuft protruding outward from the surface of the body and comprising a plurality of fibers. 4. The absorbent member of claim 3, wherein the fibrous bundle projection comprises a thermally fusible portion, wherein a plurality of fibers are thermally fusible with each other. 5. The absorbent member according to claim 3, wherein each of the fibrous clusters comprises a main body part defined by base surfaces and a body surface, and the protrusion length of the protruding part of the fibrous bundle from the main body part is 0.2 mm or more and 7.0 mm or less. 6. The absorbent member of claim 1, wherein the outer shape of each of the fibrous clusters is a cuboid shape or a disc shape. 7. The absorbent member of claim 1, wherein each of the base surfaces is rectangular in plan view and the short side of the rectangle is less than or equal to the thickness of the absorbent member. 8. An absorbent member according to claim 7, wherein the ratio of the length of the short side of each of the base surfaces to the thickness of the absorbent member (first/last) is from 0.08 or more to 0.5 or less. 9. The absorbent member of claim 7, wherein the short side length of each of the base surfaces is 0.3 mm or more and 10.0 mm or less. 10. An absorbent member according to claim 7, wherein the length of the long side in each of the base surfaces is 0.3 mm or more and 30.0 mm or less. 11. The absorbent member of claim 1, wherein the projected views in two directions of the absorbent member at right angles to each other have superimposed portions of a plurality of fibrous clusters in an arbitrary unit area of 10 mm ² . 12. The absorbent body of claim 1, wherein each of the fibrous clusters comprises a plurality of thermoplastic fibers in the form of synthetic fibers and has a three-dimensional structure in which the plurality of thermoplastic fibers are thermally fused to each other. 13. An absorbent body according to claim 1, wherein the weight ratio (first/last) of fibrous clusters and included absorbent fibers is from 20/80 to 80/20. 14. The absorbent body of claim 1, wherein (in the absorbent body) some of the fibrous clusters are entangled with other fibrous clusters or absorbent fibers and some of the fibrous clusters are entangled with other fibrous clusters or absorbent fibers. 15. The absorbent body of claim 14, wherein the total amount of entangled fibrous clusters and entanglement fibrous clusters is 50% or more of the total fibrous clusters in the absorbent body. 16. Absorbent element according to claim. 1, in which the number of fibrous clusters containing bonding parts with other fibrous clusters or absorbent fibers through fiber entanglement, is 70% or more of the total number of fibrous clusters containing bonding parts with other fibrous clusters or absorbent fibers . 17. Absorbent element according to claim 1, in which the fibrous clusters are obtained from a nonwoven material. 18. Absorbent element according to claim 1, in which the ratio (N ₁ /N ₂ ) of the number N _{1 of the} end parts of the fibers per unit area on the base surfaces to the number N _{2 of the} end parts of the fibers per unit area on the surface of the body is 0 or more and 0 .90 or less. 19. The absorbent item of Claim. 1, wherein the number of end portions of fibers per unit area on the base surfaces of the end portions is 0 fibers / mm ² or more and 8, the end portions of the fibers / mm ² or less. 20. The absorbent item of Claim. 1, wherein the number of end portions of fibers per unit area on the body surface of the end portions 5 fibers / mm ² or more and 50 the end portions of the fibers / mm ² or less. 21. Absorbent element containing a plurality of fibrous clusters containing synthetic fibers, and a plurality of absorbent fibers, in which fibrous clusters are entangled with each other or fibrous clusters and absorbent fibers are entangled, where each of the fibrous clusters contains two opposite base surfaces and a body surface, which two base surfaces are connected, and each of the fibrous clusters contains a protruding part of the fibrous bundle protruding outward from the surface of the body and containing a plurality of fibers. 22. The absorbent body of claim 21, wherein the total area of the two base surfaces is greater than the total surface area of the body. 23. An absorbent article containing an absorbent element according to claim 1 or 21. 24. An absorbent article according to claim 23, wherein the absorbent article in the dry state has a torque of 0.20 mNm or more and 1.30 mNm or less. 25. An absorbent article according to claim 23, wherein the absorbent article, when wet, has a torque of 0.20 mNm or more and 1.20 mNm or less.

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