JP7045836B2 - Absorbent article - Google Patents

Description

The present invention relates to an absorbent article such as a menstrual napkin, and more particularly to an absorbent article including a surface sheet having a plurality of protrusions formed on a skin-facing surface.

Absorbent articles such as disposable diapers and menstrual napkins are generally sold in a folded shape so that the surface in contact with the wearer's skin is on the inside.

In the individual package of the absorbent article, the applicant applies between the circumferential leak-proof groove extending in the vertical direction for integrating the surface sheet and the absorber and the left and right grooves constituting the peripheral leak-proof groove. When the packaging state of the individual package is unpacked by providing a central groove extending in the lateral direction and arranging the individual packaging line of the individual package at a specific position between the peripheral leak-proof groove and the central groove. It has been proposed that wrinkles are less likely to occur in the portion of the surface sheet corresponding to the bent portion of the absorbent article (Patent Document 1).

Apart from this, as a technique for improving the absorber, for example, in Patent Document 2, an absorber containing a thermoplastic resin fiber and a cellulosic water-absorbent fiber, wherein the thermoplastic resin fiber is the absorber. Those exposed on both the surface on the front sheet side and the surface on the back sheet side of the absorber are described. According to the absorber described in Patent Document 1, the thermoplastic resin fiber functions as a skeleton for holding other components of the absorber such as a cellulosic water-absorbent fiber, and is therefore soft and resistant to twisting. ..

Further, Patent Document 3 describes an absorber containing heat-sealed fibers, a non-woven fabric piece in which the fibers are bonded in advance to give a three-dimensional structure, and hydrophilic fibers. This non-woven fabric piece having a three-dimensional structure is manufactured by crushing the non-woven fabric into small pieces using a crushing means such as a cutter mill method, and FIGS. 1 and 1 of the same document are produced due to such a manufacturing method. As described in No. 3, it has an indefinite shape and does not substantially have a portion that can be regarded as a flat surface.

Further, Patent Document 4 describes a fine web having a relatively dense fine fiber nucleus and a fiber or a fiber bundle extending outward from the nucleus, and the fine web and wood pulp or a water-absorbing polymer. It is described that a non-woven web mixed with particles can be used as an absorber for absorbent articles. This fine web is manufactured by peeling or tearing off a raw material sheet such as a non-woven fabric, and like the non-woven fabric piece described in Patent Document 3, has an irregular shape and a portion that can be regarded as a flat surface. Substantially does not have.

Japanese Unexamined Patent Publication No. 2010-178932. Japanese Unexamined Patent Publication No. 2015-16296 JP-A-2002-301105 Japanese Unexamined Patent Publication No. 1-156560

When an absorbent article such as a sanitary napkin is unfolded from a state in which it is individually wrapped, there has been a problem that the surface sheet is wrinkled along the folding curve at the time of folding. If the absorbent article has creases on the surface facing the skin, it may cause a feeling of discomfort when worn, and the creases may make it difficult for the absorbent article to adhere to the wearer's skin, resulting in leakage of excrement. be. The technique disclosed in Patent Document 1 may not be sufficient to improve wrinkles during long-term storage. Patent Documents 2 to 4 do not describe any problem of such creases, and have not yet provided a technique capable of solving such a problem.

An object of the present invention is to provide an absorbent article which is less likely to be wrinkled when folded.

The present invention comprises an absorber including an absorbent core and a surface sheet arranged on the skin-facing surface side of the absorber, and has a vertical direction corresponding to the front-back direction of the wearer and a horizontal direction orthogonal to the vertical direction. The absorbent core contains fiber lumps containing synthetic fibers and hydrophilic fibers, and the fiber lumps or the fiber lumps and the hydrophilic fibers are entangled with each other. The fiber mass comprises two opposing basic surfaces and a skeleton surface connecting the two basic surfaces, and the absorbent article is folded on the skin facing surface of the surface sheet with the surface sheet inside. The fold curve used in the case extends in a predetermined direction, and the fold curve straddles the portion of the absorbent core that overlaps the fold curve in the thickness direction and straddles the fold curve in a direction intersecting the extension direction. It is an absorbent article in which fiber lumps are present and there is a portion where the fiber lumps are not fused to each other.

The absorbent article of the present invention is less likely to be wrinkled due to individual packaging, and therefore, the discomfort during wearing due to the wrinkles is reduced, and the absorbent article is less likely to adhere to the wearer's skin and cause leakage when worn.

FIG. 1 is a plan view schematically showing an example of a sanitary napkin according to an embodiment of the absorbent article of the present invention, with the skin facing surface side (surface sheet side) partially broken. FIG. 2 is a cross-sectional view schematically showing a cross section of the folding curve (first folding curve) of FIG. FIG. 3 is a schematic perspective view of the individual body of the sanitary napkin shown in FIG. FIG. 4 is a vertical cross-sectional view schematically showing a cross section of the sanitary napkin shown in FIG. 3 along the vertical direction. 5 (a) and 5 (b) are schematic perspective views of the fiber mass according to the present invention, respectively. FIG. 6 is an explanatory diagram of a method for producing a fiber mass according to the present invention. 7A and 7B are explanatory views of the positional relationship between the folding curve and the fiber mass, and FIGS. 7A and 7B are modes within the scope of the present invention, FIGS. 7C and 7D. Is a form outside the scope of the present invention.

Hereinafter, the absorbent article of the present invention will be described with reference to the drawings based on the preferred embodiment thereof. 1 and 2 show a menstrual napkin 1 which is an embodiment of the absorbent article of the present invention. The napkin 1 includes an absorbent body 4 including an absorbent core 40 and a surface sheet 2 arranged on the skin-facing surface side of the absorbent body 4, and is provided in the front-back direction of the wearer, that is, from the ventral side to the crotch portion. It has a vertical direction X corresponding to a direction extending to the dorsal side and a horizontal direction Y orthogonal to the vertical direction X.

In the present specification, the "skin facing surface" is a surface of the absorbent article or its constituent members (for example, a surface sheet) that is directed toward the wearer's skin side when the absorbent article is worn, that is, the wearer's skin relatively. The "non-skin facing surface" is the surface of the absorbent article or its constituents that faces the opposite side of the skin when the absorbent article is worn, that is, relatively far from the wearer's skin. On the side. The term "when worn" as used herein means a state in which a normal proper wearing position, that is, a correct wearing position of the absorbent article is maintained.

As shown in FIG. 1, the napkin 1 is located in the vertical central region B including the excretion portion facing portion (excretion point) facing the excretion portion such as the wearer's vaginal opening in the vertical direction X, and from the excretion portion facing portion. Is also divided into three categories: an anterior region A arranged on the ventral side (front side) of the wearer and a posterior region C arranged on the dorsal side (rear side) of the wearer from the excretion portion facing portion. Further, the napkin 1 is a pair of an absorbent main body 5 having a shape long in the vertical direction X and a pair of wings extending outward in the horizontal direction Y from both side portions of the absorbent main body 5 along the vertical direction X in the vertical central region B. It has parts 5W and 5W. The absorbent main body 5 is a portion that is the main body of the napkin 1, and includes the front surface sheet 2, the back surface sheet 3, and the absorbent body 4, and has a front region A, a vertical center region B, and a rear region C in the vertical direction X. It is divided into three categories.

The vertical central region of the absorbent article of the present invention is a wing in the vertical direction (longitudinal direction, X direction in the figure) of the absorbent article when the absorbent article has a wing portion like the napkin 1. It means a region having a portion, and taking napkin 1 as an example, it is a region sandwiched between a root along the vertical direction X of one wing portion 5W and a root along the vertical direction X of the other wing portion 5W. Further, the excretion portion facing portion of the absorbent article having no wing portion is used when the absorbent article is folded into a tri-fold individual packaging form, and the absorbent article is crossed in the lateral direction (width direction, Y in the figure). With respect to the two fold curves crossing the direction) (the fold curve corresponding to the fold curve 8 in FIG. 1), the vertical front end of the absorbent article, that is, the ventral side of the wearer at both ends of the absorbent article in the vertical direction. It means the area surrounded by the first folding curve and the second folding curve counting from the vertical end arranged in.

In the napkin 1, the absorber 4 includes a liquid-absorbable absorbent core 40 and a liquid-permeable core wrap sheet 41 that covers the outer surface of the absorbent core 40. Like the absorbent body 5, the absorbent core 40 has a long shape in the vertical direction X in a plan view as shown in FIG. 1, and the longitudinal direction of the absorbent core 40 is one with respect to the vertical direction X of the napkin 1. However, the width direction of the absorbent core 40 coincides with the lateral direction Y of the napkin 1. The absorbent core 40 and the core wrap sheet 41 may be bonded by an adhesive such as a hot melt type adhesive.

In the napkin 1, the core wrap sheet 41 is one continuous sheet having a width of 2 times or more and 3 times or less the length of the lateral Y of the absorbent core 40, and as shown in FIG. 2, it absorbs. It covers the entire skin-facing surface of the sex core 40 and extends outward in the lateral direction Y from both side edges along the vertical direction X of the absorbent core 40, and the extending portion thereof is below the absorbent core 40. It is rolled down to cover the entire non-skin facing surface of the absorbent core 40. In the present invention, the core wrap sheet does not have to be such a single sheet, for example, one skin-side core wrap sheet that covers the skin-facing surface of the absorbent core 40 and the skin-side. It may be a separate body from the core wrap sheet, and may include two sheets including one non-skin side core wrap sheet that covers the non-skin facing surface of the absorbent core 40.

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

As shown in FIG. 1, the side flap portions greatly project outward in the horizontal direction Y in the vertical central region B, whereby a pair of side flap portions are formed on both the left and right sides of the absorbent main body 5 along the vertical direction X. Wings 5W and 5W are extended. The wing portion 5W has a substantially trapezoidal shape in which the lower base (the side longer than the upper base) is located on the side portion side of the absorbent main body 5 in a plan view as shown in FIG. 1, and the non-skin facing surface thereof. Is formed with a wing portion adhesive portion (not shown) for fixing the wing portion 5W to clothing such as shorts. The wing portion 5W is used by being folded back toward the non-skin facing surface (outer surface) side of the crotch portion of clothing such as shorts. Before its use, the adhesive portion of the wing portion is covered with a release sheet (not shown) made of a film, a non-woven fabric, paper or the like. Further, a pair of both side portions of the absorbent body 5 on the skin-facing surface, that is, the skin-facing surface of the surface sheet 2 along the vertical direction X, overlap with the left and right side portions of the absorbent body 4 along the vertical direction X in a plan view. Side sheets 6 and 6 are arranged over substantially the entire length of the absorbent body 5 in the vertical direction X. The pair of side sheets 6 and 6 are joined to another member such as the surface sheet 2 by a known joining means such as an adhesive by a joining line (not shown) extending in the vertical direction X, respectively.

As shown in FIGS. 1 and 2, the surface sheet 2 and the absorbent core 40 are integrally recessed on the non-skin facing surface side of the absorbent core 40 on the skin facing surface of the surface sheet 2 in the absorbent main body 5. The recessed portion 7 is partially formed. In the recessed portion 7 of the napkin 1, the front surface sheet 2, the core wrap sheet 41, and the absorbent core 40 are integrally recessed toward the back surface sheet 3 side. The recessed portion 7 is formed by subjecting the napkin 1 to a known pressing process such as embossing with or without heat or ultrasonic embossing from the skin facing surface, that is, the surface sheet side, and a method for forming the recessed portion 7. It can also be called "squeezing part". The recessed portion 7 has a higher density than the peripheral portion (non-formed portion of the recessed portion) due to being formed by squeezing. Further, when the recessed portion 7 is formed by squeezing with heat, the fiber material (fiber) constituting the surface sheet 2, the core wrap sheet 41 and the absorbent core 40 at the bottom of the recessed portion 7. The lump 11, the hydrophilic fiber 12F) may be heat-sealed and integrated.

The recessed portion 7 is arranged so as to surround the central portion in the horizontal direction Y in the central portion in the vertical direction X of the absorbent core 40. As shown in FIG. 1, the recessed portion 7 is formed at least in the vertical central region B, and more specifically, from the portion of the front region A closer to the vertical central region B to the rear region C closer to the vertical central region B. It is continuous in the vertical direction X over the portion. Further, the recessed portion 7 has a linear shape in a plan view as shown in FIG. 1, and the linear recessed portion 7 has a closed annular shape in a plan view. The annular recessed portion 7 has a long shape in the vertical direction X in a plan view, and its longitudinal direction coincides with the vertical direction X. The annular recessed portion 7 is formed in a U-shape or an arc shape that is convex outward in the vertical direction X in each of the front region A and the rear region C, and the U-shaped or arc-shaped top thereof is a napkin. It is located in the center of 1 in the lateral direction Y. Further, the annular recessed portion 7 is formed in a pair of left and right linear shapes extending in the vertical direction X in the vertical central region B. As described above, the recessed portion 7 is formed so as to surround the central portion in the lateral direction Y of the vertical central region B, and the excretion portion facing portion located at the central portion is surrounded by the recessed portion 7. .. The effects that can be exerted by the formation of the recessed portion 7 are that the diffusion of the liquid in the plane direction of the absorber 4 (absorbent core 40), particularly in the lateral direction Y is suppressed, the twist of the absorber 4 is prevented, and the absorber 4 is prevented. The shape retention is improved.

When not in use, the napkin 1 is folded in the vertical direction X from the unfolded state as shown in FIG. 1 to form the individual body 10 shown in FIG. As shown in FIG. 1, a folding curve 8 used for folding the napkin 1 with the surface sheet 2 inside extends in a predetermined direction on the skin-facing surface of the surface sheet 2. In the napkin 1, the fold curve 8 exists in each of the front and rear in the vertical direction X with the excretion portion facing portion interposed therebetween, and a total of two fold curves 8 exist. One of the two folding curves 8 extends laterally Y through the base of the pair of wing portions 5W and 5W near the front region A, and the other is the rear region of each of the pair of wing portions 5W and 5W. It extends laterally Y through the base closer to C, and the two fold curves 8 are parallel to each other.

In the individual packaging body 10, the laminated body of the napkin 1 and the packaging material 10W has two folding curves crossing the laminated body in the lateral direction Y with the skin facing surface (surface sheet 2 side) of the napkin 1 inside. It is configured to be folded in three in the vertical direction X at 8 and 8. When the napkin 1 is folded in three, the pair of wing portions 5W and 5W are each folded toward the surface sheet 2. The packaging material 10W has a rectangular shape in a plan view, its longitudinal direction coincides with the vertical direction X of the napkin 1, and the non-skin facing surface (back surface sheet 3) of the napkin 1 is provided with an adhesive (not shown). It is sticky. On the upper surface of the individual packaging body 10, a fastening tape 10T is arranged so as to straddle the vertical end of the packaging material 10W in the vertical direction X. The extending portions from the side edges of the napkin 1 along the vertical direction X in the packaging material 10W are joined by known joining means such as an adhesive and a heat seal to form a sealing portion 10S. The basic configuration of the individual package 10 is the same as that of a known sanitary napkin.

To open the individual package 10, the fastening tape 10T is picked up by fingers to peel off the sealing portion 10S at the side edge portion, and then the packaging material 10W is removed and the napkin 1 is taken out. As shown in FIG. 4, there is a concern that the surface sheet 2 of the napkin 1 thus taken out may have "creases" indicated by reference numeral 100 in FIG. 4 along the folding curve 8 at the time of individual packaging. At the position where the fold curve 8 is formed in the individual package 10, a strong external force due to folding acts on the absorber 4 for a long time, so that the absorber 4 is deformed at the formed position to form creases. Such creases can cause leakage due to a decrease in the wearing feeling of the napkin 1 and a decrease in the adhesion to the wearer's skin.

Reference numeral 80 in FIG. 4 is a “crease” formed along the fold curve 8. The crease 80 is a region of a plane line of sight having a predetermined width centered on the fold curve 8, and the width thereof, that is, the extending direction of the fold curve 8 (the longitudinal direction of the fold curve, and the lateral direction Y in the napkin 1). The length in the direction orthogonal to the above is not particularly limited, but is usually about 1 to 10 mm.

In order to solve the problem of wrinkles due to individual packaging, as shown in FIG. 2, in the napkin 1, the absorbent core 40 contains a fiber mass 11 having a specific shape including the hydrophilic fiber 12F and the synthetic fiber 11F. Was decided to be contained. In addition to containing the fiber lumps 11, the absorbent core 40 is also characterized in that a plurality of fiber lumps 11 are entangled with each other or the fiber lumps 11 and the hydrophilic fibers 12F are entangled with each other. Hereinafter, the absorbent core 40 will be described.

As used herein, the term "fiber mass" is a fiber aggregate in which a plurality of fibers are grouped together and integrated. Examples of the form of the fiber mass include a sheet piece divided from a synthetic fiber sheet having a certain size. In particular, a non-woven fabric is selected as the synthetic fiber sheet, and a non-woven fabric piece cut out from the non-woven fabric into a predetermined size and shape is preferable as the fiber mass.

As described above, the sheet piece-shaped fiber mass, which is a preferred embodiment of the fiber mass according to the present invention, is not configured to accumulate a plurality of fibers to form the sheet piece, but rather than the sheet piece. It is also manufactured by cutting a fiber sheet (preferably a non-woven fabric) having a large size (see FIG. 6). The plurality of fiber lumps contained in the absorbent core according to the present invention are a plurality of sheet piece-like fiber lumps having higher stereotypes as compared with those produced by conventional techniques such as Patent Documents 3 and 4. ..

In the absorbent core 40, a plurality of fiber lumps 11 or the fiber lumps 11 and the hydrophilic fibers 12F are entangled with each other. In the absorbent core 40 of the present embodiment, a plurality of fiber lumps 11 are entangled with the constituent fibers (fibers 11F and 12F) in the absorbent core 40 to form one fiber lump continuum. Further, the plurality of fiber lumps 11 may be entangled with each other, and the fiber lumps 11 and the hydrophilic fiber 12F may be entangled with each other. Further, usually, a plurality of hydrophilic fibers 12F are also entangled with each other. At least a part of the plurality of fiber lumps 11 contained in the absorbent core 40 is entangled with other fiber lumps 11 or hydrophilic fibers 12F. In the absorbent core 40, all of the plurality of fiber masses 11 contained therein may be entangled with each other to form one fiber mass continuum, and the plurality of fiber mass continuums may be non-existent with each other. It may be mixed in the combined state.

Since the fiber mass 11 is excellent in flexibility and the like, by including it in the absorbent core 40, the absorbent core 40 is potentially excellent in flexibility and the like. In the absorbent core 40, in addition to containing such fiber lumps 11, the fiber lumps 11 or the fiber lumps 11 and the hydrophilic fiber 12F are also entangled with each other and thus bonded to each other by entanglement. 40 is more excellent in responsiveness to external force, and is excellent in shape retention, flexibility, cushioning property, compression recovery property and the like. For example, the absorbent core 40 flexibly deforms with respect to an external force (for example, the wearer's body pressure) received from various directions when the napkin 1 is worn, and can be brought into close contact with the wearer's body with good fit.

As described above, in the absorbent core 40, the fiber lumps 11 are entangled with each other or the fiber lumps 11 and the hydrophilic fiber 12F are entangled with each other. A and B are included.
Form A: A form in which the fiber lumps 11 and the like are not fused but are bonded by the entanglement of the constituent fibers 11F of the fiber lumps 11.
Form B: In the natural state of the absorbent core 40 (a state in which no external force is applied), the fiber lumps 11 and the like are not bonded to each other, but in a state where the absorbent core 40 is subjected to an external force, the fiber lumps 11 and the like are not bonded to each other. A form that can be bonded by entanglement of constituent fibers 11F. The "state in which an external force is applied to the absorbent core 40" as used herein is, for example, a state in which a deformable force is applied to the absorbent core 40 while the absorbent article to which the absorbent core 40 is applied is being worn. ..

Thus, in the absorbent core 40, as in Form A, the fiber mass 11 is bonded to another fiber mass 11 or the hydrophilic fiber 12F by entanglement, that is, "entanglement" between the fibers, and other forms. Like B, it also exists in a state where it can be entangled with other fiber lumps 11 or hydrophilic fibers 12F, and the binding by entanglement of such fibers more effectively expresses the action and effect of the above-mentioned absorbent core 40. It is one of the important points. However, it is preferable that the absorbent core 40 has the "entanglement" of Form A from the viewpoint of shape retention. Since the entanglement of the fibers has no adhesive component or fusion and is performed only by the entanglement of the fibers, the entanglement is performed as compared with the entanglement by "fusion of fibers" as described in Patent Document 3, for example. The individual elements (fiber mass 11, hydrophilic fiber 12F) have a high degree of freedom of movement, so that the individual elements can move to the extent that the unity as an aggregate composed of them can be maintained. As described above, the absorbent core 40 is deformed when it receives an external force because the plurality of fiber lumps 11 contained therein or the fiber lumps 11 and the hydrophilic fiber 12F are relatively loosely bonded to each other. It has a possible and gentle shape retention property, and has both shape retention property, cushioning property, compression recovery property, and the like at a high level.

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

However, the remainder after removing "fusion via the fiber mass 11" formed in the absorbent core 40 as a result of being integrated with other members of the absorbent article such as the above-mentioned leak-proof groove from the absorbent core 40. In that part, that is, in the absorbent core 40 itself, it is desirable that the fiber lumps 11 are bonded to each other or the fiber lumps 11 and the hydrophilic fibers 12F are bonded only by "entanglement of fibers".

From the viewpoint of more reliably expressing the action and effect of the absorbable core 40 described above, the form A "fiber mass 11 bound by entanglement" and the form B "fiber mass 11 in a confoundable state" The total number of the fibers is preferably half or more, more preferably 70% or more, and more preferably 80% or more with respect to the total number of fiber lumps 11 in the absorbent core 40.
From the same viewpoint, the number of fiber lumps 11 having the "entanglement" of Form A is 70% or more, particularly 80% or more of the total number of fiber lumps 11 having a binding portion with other fiber lumps 11 or hydrophilic fibers 12F. It is preferable to have.

FIG. 5 shows two typical outer shapes of the preferred form of the fiber mass 11. The fiber mass 11A shown in FIG. 5A has a rectangular parallelepiped shape more specifically than the prismatic shape, and the fiber mass 11B shown in FIG. 5B has a disk shape. The fiber lumps 11A and 11B are common in that they include two opposing base planes 111 and a skeleton plane 112 connecting the two base planes 111. Both the basic surface 111 and the skeleton surface 112 are at a level applied when evaluating the degree of surface unevenness in an article mainly composed of this type of fiber, and are portions where it is recognized that there is substantially no unevenness.

The rectangular parallelepiped-shaped fiber mass 11A in FIG. 5A has six flat surfaces, of which two facing surfaces having the maximum area are the basic surfaces 111, and the rest. Each of the four surfaces is a skeletal surface 112. The basic surface 111 and the skeleton surface 112 intersect each other, and more specifically, are orthogonal to each other.
The disk-shaped fiber mass 11B of FIG. 5B has two flat surfaces facing each other in a circular shape in a plan view and a curved peripheral surface connecting the two flat surfaces, where the two flat surfaces are formed. Each surface is a basic surface 111, and the peripheral surface is a skeleton surface 112.
The fiber lumps 11A and 11B are also common in that the skeleton surface 112 has a quadrangular shape, more specifically, a rectangular shape in a plan view.

The plurality of fiber lumps 11 contained in the absorbent core 40 have two opposed basic surfaces 111 and a skeleton surface 112 connecting both basic surfaces 111, such as the fiber lumps 11A and 11B shown in FIG. 5, respectively. It differs from the non-woven fabric pieces or fine webs described in Patent Documents 3 and 4, which are irregular fiber aggregates, in that they are provided with "standard fiber aggregates". In other words, when any one fiber mass 11 in the absorbent core 40 is seen through (for example, when observed with an electron microscope), the fluoroscopic shape of the fiber mass 11 depends on the observation angle, and one fiber. Where there are a large number of perspective shapes per mass 11, each of the plurality of fiber masses 11 in the absorbent core 40 connects two opposing basic surfaces 111 and both basic surfaces 111 as one of the many perspective shapes. It has a specific perspective shape with a skeletal surface 112. The plurality of non-woven fabric pieces or fine webs contained in the absorbers (absorbent cores) described in Patent Documents 3 and 4 substantially cover "planes" such as the basic surface 111 and the skeleton surface 112, that is, widened portions. It is not a "fixed form" because it has different outer shapes from each other.

As described above, Patent Documents 3 and 4 describe that the plurality of fiber lumps 11 contained in the absorbent core 40 are "standard fiber aggregates" defined by the basic surface 111 and the skeleton surface 112. Compared with the case of an amorphous fiber aggregate as described above, the uniform dispersibility of the fiber mass 11 at a predetermined portion (skin facing surface side) of the absorbent core 40 is improved, so that the fiber aggregate such as the fiber mass 11 is improved. By blending the body into the absorbent core 40, the expected effects (effects of improving the cushioning property, flexibility, compression recovery property, etc. of the absorbent body) will be stably exhibited. Further, in particular, in the case of the rectangular parallelepiped fiber mass 11 as shown in FIG. 5 (a), the outer surface thereof is composed of six surfaces of two basic surfaces 111 and four skeleton surfaces 112, and thus is shown in FIG. 5 (b). Compared to the disk-shaped fiber mass 11 having three outer surfaces, it is possible to have a relatively large number of contact opportunities with other fiber mass 11 or the hydrophilic fiber 12F, and the entanglement is enhanced and the shape retention property is improved. It can also lead to improvement of such things.

In the present embodiment, in the fiber mass 11, the basic surface 111 has a larger area than the skeleton surface 112. In the fiber lumps 11A and 11B shown in FIG. 5, in addition to the magnitude relationship of "area of basic surface 111> area of skeleton surface 112", the total area of the two basic surfaces 111 is the total area of the skeleton surface 112. There is also a large-small relationship that is larger than. That is, in the rectangular parallelepiped fiber mass 11A of FIG. 5 (a), the total area of each of the two basic surfaces 111 is larger than the total area of each of the four skeleton surfaces 112, and FIG. 5 (b). In the disk-shaped fiber mass 11B, the total area of each of the two basic surfaces 111 is larger than the area of the skeleton surface 112 forming the peripheral surface of the disk-shaped fiber mass 11B. In any of the fiber lumps 11A and 11B, the basic surface 111 is the surface having the largest area among the plurality of surfaces of the fiber lumps 11A and 11B.

In this way, the fiber mass 11 includes two basic surfaces 111 facing each other and a skeleton surface 112 connecting them, and has a magnitude relationship of "area of basic surface 111> area of skeleton surface 112". As a result of the above-mentioned magnitude relationship that "the total area of both basic surfaces 111 is larger than that of the skeleton surface 112", the basic surface 111 having a relatively large area mainly has the liquid permeability of the fiber mass 11. The skeletal surface 112, which contributes to the improvement and has a relatively small area, mainly strongly supports the basic surface 111, which contributes to its liquid permeability, and the external pressure such as the body pressure of the wearer of the napkin 1 absorbs the core. Even when it is applied to 40, it acts so as to maintain the liquid permeability of the basic surface 111. Therefore, the absorbent core 40 including a plurality of fiber lumps 11 having such a characteristic outer shape can have high cushioning property even after liquid absorption, are not easily twisted, and are excellent in liquid drawing property.

The reason why the fiber lump 11 is such a "standard fiber aggregate" defined by the two basic surfaces 111 and the skeleton surface 112 intersecting both basic surfaces 111 is due to the manufacturing method of the fiber lump 11. Is. As shown in FIG. 6, the fiber lump 11 is produced by cutting a raw material fiber sheet 10bs (a sheet having the same composition as the fiber lump 11 and having a larger size than the fiber lump 11) as a raw material by using a cutting means such as a cutter. The plurality of fiber lumps 11 made by cutting into a fixed shape and thus produced are uniform in shape and size. FIG. 6 is a diagram illustrating a method for manufacturing the rectangular parallelepiped-shaped fiber mass 11A of FIG. 5A, and the dotted line in FIG. 6 indicates a cutting line. The absorbent core 40 contains a plurality of fiber lumps 11 having uniform shapes and dimensions obtained by cutting the fiber sheet into a fixed shape. As described above, a non-woven fabric is preferable as the raw material fiber sheet 10bs.

In the rectangular parallelepiped-shaped fiber mass 11A of FIG. 5A, as shown in FIG. 6, the raw material fiber sheet 10bs intersects (more specifically, orthogonally) the first direction D1 and the first direction D1 in the second direction. It is manufactured by cutting into D2 to a predetermined length. Both directions D1 and D2 are each a predetermined direction in the plane direction, and the sheet 10bs is cut along the thickness direction Z orthogonal to the plane direction. As described above, in a plurality of rectangular parallelepiped fiber lumps 11A obtained by cutting the raw material fiber sheet 10bs into a so-called diced pattern, the cut surface, that is, the surface that comes into contact with a cutting means such as a cutter when the sheet 10bs is cut is usually formed. The skeleton surface 112, that is, the non-cut surface, that is, the surface that does not come into contact with the cutting means, is the basic surface 111. The basic surface 111 is a front and back surface (a surface orthogonal to the thickness direction Z) of the sheet 10bs, and as described above, is the surface having the largest area among the plurality of surfaces of the fiber mass 11A.

The spacing L1a (spacing in the first direction, see FIG. 6) and the spacing L2a (spacing in the second direction, see FIG. 6) at the time of cutting the raw material fiber sheet 10bs are such that the fiber mass 11 exerts a predetermined effect. From the viewpoint of ensuring the necessary dimensions, the thickness is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 30 mm or less, still more preferably 15 mm or less.

The above description of the fiber mass 11A basically applies to the disk-shaped fiber mass 11B of FIG. 5 (b). The only substantial difference from the fiber mass 11A is the cutting pattern of the raw material fiber sheet 10bs, and when the sheet 10bs is cut into a fixed shape to obtain the fiber mass 11B, the shape of the fiber mass 11B is matched to the plan view shape. The sheet 10bs may be cut into a circular shape.

Further, the outer shape of the fiber mass 11 is not limited to that shown in FIG. 5, and the basic surface 111 and the skeleton surface 112 are both flat surfaces that are not curved as in the respective surfaces 111 and 112 of FIG. 5 (a). Alternatively, it may be a curved surface such as the skeleton surface 112 (peripheral surface of the disk-shaped fiber mass 11B) in FIG. 5 (b). Further, the basic surface 111 and the skeleton surface 112 may have the same shape and dimensions, and specifically, for example, the outer shape of the fiber mass 11A may be a cubic shape.

As described above, the two types of surfaces (basic surface 111 and skeleton surface 112) of the fiber mass 11 (11A, 11B) are used to cut the raw material fiber sheet 10bs by a cutting means such as a cutter when manufacturing the fiber mass 11. It is classified into a cut surface (skeleton surface 112) formed by the sheet 10bs and a non-cut surface (basic surface 111) that is inherently possessed by the sheet 10bs and does not come into contact with the cutting means. Due to the difference in whether or not the cut surface is used, the cut surface, the skeleton surface 112, is characterized in that the number of fiber ends per unit area is larger than that of the non-cut surface, the basic surface 111. Has. The term "fiber end" as used herein means the end in the length direction of the constituent fibers 11F of the fiber mass 11. Normally, the fiber end is also present on the basic surface 111, which is a non-cut surface, but the skeleton surface 112 is formed by cutting because it is a cut surface formed by cutting the raw material fiber sheet 10bs. A large number of fiber ends consisting of cut ends of the constituent fibers 11F are present in the entire skeleton surface 112, that is, the number of fiber ends per unit area is larger than that of the basic surface 111. ..

At the fiber ends existing on each surface (basic surface 111, skeleton surface 112) of the fiber mass 11, the fiber mass 11 is between the other fiber mass 11 included in the absorbent core 40 and the hydrophilic fiber 12F. Useful for forming confounding. Further, in general, the larger the number of fiber ends per unit area, the better the entanglement, which may lead to the improvement of various characteristics such as the shape retention of the absorbent core 40. As described above, the number of fiber ends per unit area on each surface of the fiber mass 11 is not uniform, and the number of such fiber ends per unit area is "skeleton surface 112> basic surface 111". Since the magnitude relationship is established, the entanglement with other fibers (other fiber mass 11, hydrophilic fiber 12F) via the fiber mass 11 differs depending on the surface of the fiber mass 11, and the skeleton surface 112 is the basic surface 111. Highly entangled compared to. That is, the bond by entanglement with other fibers via the skeleton surface 112 has a stronger bonding force than that through the basic surface 111, and in one fiber mass 11, the basic surface 111 and the skeleton surface There may be a difference in the bonding force with other fibers from 112. In general, the stronger the bonding force, the more the degree of freedom of movement of the bonded fibers is limited, and the strength (shape retention) of the absorbent core 40 as a whole is improved, but the softness tends to be decreased. ..

As described above, in the absorbent core 40, each of the plurality of fiber lumps 11 contained therein has two types of binding forces with respect to other fibers (other fiber lumps 11, hydrophilic fiber 12F) around the absorbent core 40. The absorbent core 40 has an appropriate softness and strength (shape retention). When the absorbent core 40 having such excellent properties is used as an absorber of the absorbent article according to a conventional method, it is possible to provide a comfortable wearing feeling to the wearer of the absorbent article. At the same time, the inconvenience that the absorbent core 40 is destroyed by an external force such as the wearer's body pressure at the time of wearing is effectively prevented.

In particular, in the fiber mass 11 (11A, 11B) shown in FIG. 5, as described above, the area of the basic surface 111 is larger than the area of the skeleton surface 112, and the total area of the two basic surfaces 111 is the skeleton surface. Where it is larger than the total area of 112, this is due to the basic surface 111, which has a relatively small number of fiber ends per unit area and therefore has relatively low entanglement with other fibers. Means that the total area is larger than the skeletal surface 112 having the opposite property. Therefore, the fiber lumps 11 (11A, 11B) shown in FIG. 5 have other fibers (other fiber lumps 11, hydrophilic fibers 12F) in the vicinity as compared with the fiber lumps having fiber ends uniformly present on the entire surface. ) Is easily suppressed, and even if it is entangled with other fibers in the vicinity, it is easy to entangle with a relatively weak binding force. Gender, flexibility, etc. can be imparted.

On the other hand, the nonwoven fabric pieces or fine webs described in Patent Documents 2 and 3 are basically manufactured by cutting the raw material fiber sheet into an irregular shape by a cutting machine such as a mill cutter as described above. It is not a fixed-form sheet piece-like fiber mass having a "face" like the surface 111 or the skeleton surface 112, and moreover, the external force of the cutting process is applied to the entire fiber mass at the time of its manufacture, so that the constituent fibers The fiber ends of the above are randomly formed in the entire fiber mass, and it is difficult for the fiber ends to sufficiently exhibit the above-mentioned effects.

It is preferable to set the dimensions and the like of each part of the fiber mass 11 (11A, 11B) as follows. The dimensions of each part of the fiber mass 11 can be measured based on an electron micrograph or the like.
When the basic surface 111 has a rectangular shape in a plan view as shown in FIG. 5A, the length L1 of the short side 111a is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 10 mm or less. , More preferably 6 mm or less.
The length L2 of the long side 111b of the basic surface 111 having a rectangular shape in a plan view is preferably 0.3 mm or more, more preferably 2 mm or more, and preferably 30 mm or less, still more preferably 15 mm or less.
As shown in FIG. 5, when the basic surface 111 is the surface having the maximum area among the plurality of surfaces of the fiber mass 11, the length L2 of the long side 111b is the maximum transfer length of the fiber mass 11. The maximum transfer length corresponds to the diameter of the basic surface 111 having a circular shape in a plan view in the disk-shaped fiber mass 11B.
The ratio of the length L1 of the short side 111a to the length L2 of the long side 111b is preferably 0.003 or more, more preferably 0.025 or more, and preferably 1 or less, more preferably 1 or less, as L1 / L2. It is 0.5 or less. In the present invention, the plan view shape of the basic surface 111 is not limited to the rectangular shape as shown in FIG. 5A, but may be a square shape, that is, the ratio of the lengths L1 and L2 of the two sides orthogonal to each other is , L1 / L2 may be 1.
The thickness T of the fiber mass 11, that is, the length T between the two opposing basic surfaces 111 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and preferably 10 mm or less, still more preferably 6 mm or less. be.

From the viewpoint of further improving the cushioning property of the absorbent core 40, it is preferable that the plurality of fiber lumps 11 are present so as to overlap each other in the thickness direction in the absorbent core 40. More specifically, in the projection view in the thickness direction of the absorbent core 40 (when the absorbent core 40 is observed from the skin facing surface or the non-skin facing surface), a plurality of fibers are formed in an arbitrary 10 mm square unit region. It is preferable that the overlapping portion of the mass 11 is present. By the presence of the plurality of fiber lumps 11 in the absorbent core 40 so as to overlap in the thickness direction in this way, in addition to improving the cushioning property of the absorbent core 40, menstrual blood or the like is further contained in the absorbent core 40. It is expected that the liquid absorbency of the absorbent core will be improved due to the formation of a temporary stock space capable of temporarily holding the body fluid of the body fluid. From the same viewpoint, the fiber mass 11 is preferably uniformly dispersed over the entire surface direction of the absorbent core 40, and more preferably uniformly dispersed over the entire absorbent core 40.

The constituent fibers 11F of the fiber mass 11 include synthetic fibers. The synthetic fiber used as the fiber 11F is preferably a hydrophobic synthetic fiber. Since the constituent fibers 11F of the fiber mass 11 are hydrophobic fibers having low hydrophilicity, not only when the absorbent core 40 is in a dry state, but also in a wet state by absorbing water (body fluid such as urine and menstrual blood). Even in the case of, the action effect (improvement effect such as shape retention, flexibility, cushioning property, compression recovery property, and resistance to twisting) due to the presence of the above-mentioned fiber mass 11 can be stably exerted. .. The fiber 11F is more preferably hydrophobic and non-absorbent. The content of the synthetic fiber as the constituent fiber 11F in the fiber mass 11 is preferably 90% by mass or more with respect to the total mass of the fiber mass 11, and 100% by mass, that is, the fiber mass 11 is formed only from the synthetic fiber. Most preferably. In particular, when the synthetic fiber as the constituent fiber 11F is a non-water-absorbent fiber, the action and effect caused by the presence of the fiber mass 11 described above are more stably exhibited.

Similarly, from the viewpoint of enabling the absorbent core 40 to exhibit excellent effects in shape retention, flexibility, cushioning property, compression recovery property, resistance to twisting, etc. in both a dry state and a wet state. , The fiber mass 11 preferably has a three-dimensional structure in which a plurality of thermoplastic fibers are heat-fused together. Further, in order to obtain a fiber mass 11 in which a plurality of heat-sealed portions are three-dimensionally dispersed, the synthetic fiber used as the constituent fiber 11F of the fiber mass 11 is preferably a thermoplastic fiber. In order to obtain a fiber mass 11 in which a plurality of heat-sealed portions are three-dimensionally dispersed, the raw material fiber sheets 10bs (see FIG. 6) may be similarly configured, and such a plurality of heat treatments may be obtained. As described above, the raw material fiber sheet 10bs in which the fused portions are three-dimensionally dispersed can be manufactured by subjecting a web or a non-woven fabric mainly composed of thermoplastic fibers to a heat treatment such as hot air treatment.

Examples of the hydrophobic and non-water-absorbent synthetic resin (thermoplastic resin) suitable as a material for the constituent fibers 11F of the fiber mass 11 include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; nylon 6, nylon 66 and the like. Polyamide; Polyacrylic acid, polymethacrylic acid alkyl ester, polyvinyl chloride, polyvinylidene chloride and the like can be mentioned, and one of these can be used alone or in combination of two or more. The fiber 11F may be a single fiber made of one kind of synthetic resin (thermoplastic resin) or a blend polymer in which two or more kinds of synthetic resins are mixed, or may be a composite fiber. The composite fiber referred to here is a synthetic fiber (thermoplastic fiber) obtained by compounding two or more kinds of synthetic resins having different components with a spinneret and spinning them at the same time, and a plurality of components are continuous in the length direction of the fiber. A structure that is mutually bonded within a single fiber. The form of the composite fiber includes a core sheath type, a side-by-side type, and the like, and is not particularly limited.

On the other hand, as the hydrophilic fiber 12F used in combination with the fiber mass 11, the hydrophilic fiber conventionally used as a material for forming an absorber of this kind of absorbent article can be used, and for example, coniferous pulp or broadleaf pulp. Natural fibers such as wood pulp such as cotton pulp and non-wood pulp such as cotton pulp and hemp pulp; modified pulp such as cationized pulp and marcelled pulp; recycled fibers such as cupra and rayon; semi-synthetic fibers such as acetate. , One of these can be used alone or in combination of two or more. Considering that the main role of the hydrophilic fiber 12F is to improve the liquid absorbency of the absorbent core 40, the water-absorbent fiber is particularly preferable as the hydrophilic fiber 12F, and among the above-mentioned hydrophilic fibers, the natural fiber is particularly preferable. Regenerated fibers (cellulosic fibers) are preferable, and pulp-based (cellulose-based) water-absorbent fibers are particularly preferable.

In the absorbent core 40, the content mass ratio of the fiber mass 11 and the hydrophilic fiber 12F is not particularly limited, and is appropriately adjusted according to the types of the constituent fibers (synthetic fiber) 11F and the hydrophilic fiber 12F of the fiber mass 11. Just do it. For example, when the constituent fiber 11F of the fiber mass 11 is a thermoplastic fiber (hydrophobic and non-water-absorbent synthetic fiber) and the hydrophilic fiber 12F is a cellulose-based fiber (water-absorbent fiber), the predetermined effect of the present invention can be obtained. From the viewpoint of ensuring reliable performance, the content mass ratio of the fiber mass 11 and the hydrophilic fiber 12F is preferably 20/80 to 80/20 as the former (fiber mass 11) / the latter (hydrophilic fiber 12F). , More preferably 40/60 to 60/40.

The content of the fiber mass 11 in the absorbent core 40 is preferably 20% by mass or more, more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 80% by mass, based on the total mass of the absorbent core 40. Is 60% by mass or less.
The content of the hydrophilic fiber 12F in the absorbent core 40 is preferably 20% by mass or more, more preferably 40% by mass or more, and preferably 80% by mass or less, based on the total mass of the absorbent core 40. It is preferably 60% by mass or less.

The basis weight of the fiber mass 11 in the absorbent core 40 is preferably 32 g / m ² or more, more preferably 80 g / m ² or more, and preferably 640 g / m ² or less, still more preferably 480 g / m ² or less. ..
The basis weight of the hydrophilic fiber 12F in the absorbent core 40 is preferably 32 g / m ² or more, more preferably 80 g / m ² or more, and preferably 640 g / m ² or less, still more preferably 480 g / m ² or less. be.

The absorbent core 40 may contain other components other than the fiber mass 11 and the hydrophilic fiber 12F, and a water-absorbing polymer can be exemplified as the other component. As the water-absorbent polymer, a particulate polymer is generally used, but a fibrous polymer may also be used. When a particulate water-absorbent polymer is used, its shape may be spherical, lumpy, bale-shaped or amorphous. The average particle size of the water-absorbent polymer is preferably 10 μm or more, more preferably 100 μm or more, and preferably 1000 μm or less, still more preferably 800 μm or less. As the water-absorbent polymer, a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid can generally be used. Examples thereof include polyacrylic acid and salts thereof, and polymethacrylic acid and salts thereof.

As described above, the absorbent core 40 contains the fiber mass 11 having a specific shape including the synthetic fiber 11F and the hydrophilic fiber 12F, and the plurality of fiber masses 11 or the fiber mass 11 and the hydrophilic fiber 12F are fused together. Since it forms a "movable region" that is relatively loosely connected by being entangled without wearing it, even if an external force such as the wearer's body pressure acts on the absorbent core 40 while wearing the napkin 1. Due to the presence of such a movable region, it is flexible and resistant to twisting, can exhibit a high fit to the wearer's skin, and can also exhibit a gentle shape retention due to the entanglement of the fiber materials. In the napkin 1, since the absorbent core 40 which is flexible and has excellent cushioning property, compression recovery property, etc. is arranged on the non-skin facing surface side of the surface sheet 2, the napkin 1 is individually packaged as shown in FIG. Even when the body 10 is stored for a long time, it is difficult for creases to be formed on the surface sheet 2 at the position where the fold curve 8 is formed.

Further, the napkin 1 is provided with an absorbent core 40 having excellent cushioning properties and the like, and the fold curve is also caused by the fact that the fiber lumps 11 are in a specific arrangement and in a specific state at the formation position of the fold curve 8. The formation of creases at the formation position of 8 is inhibited. That is, in the napkin 1, as shown in FIGS. 7 (a) and 7 (b), the fold is formed at a portion of the absorbent core 40 that overlaps the fold curve 8 in the thickness direction (a portion that overlaps the fold curve 8 in a plan view). There is a fold curve straddling fiber lump 11S that straddles the curve 8 in a direction intersecting the extending direction (longitudinal direction of the fold curve 8), and there is a portion where the fiber lumps 11 are not fused to each other. The fold curve straddling fiber lump 11S is the same as the other fiber lumps 11 except that the fold curve straddling fiber lump 11S is arranged so as to straddle the fold curve 8. In the form shown in FIGS. 7 (a) and 7 (b), the folded curve straddling fiber mass 11S straddles the folded curve 8 in a direction (longitudinal direction X) orthogonal to its extending direction (horizontal direction Y). ..

Even if the absorbent core 40 has excellent cushioning property or the like, when the fiber mass 11 does not exist at all in the portion of the absorbent core 40 that overlaps the fold curve 8 in the thickness direction, for example, as shown in FIG. 7 (c). , When the fibrous mass 11 having a rectangular shape in a plan view is arranged so that its longitudinal direction coincides with the extending direction of the folding curve 8 (horizontal direction Y in the illustrated form), or as shown in FIG. 7 (d). If the fiber mass 11 is relatively small (the maximum transfer length in a plan view is short) and it is difficult to arrange the folding curve 8 in the direction intersecting the extending direction, the folding curve in the absorbent core 40 Since a hydrophilic fiber layer consisting of only the hydrophilic fiber 12F and having poor cushioning property is continuous over the entire length of the fold curve 8 at the portion overlapping with 8 in the thickness direction, the surface sheet 2 is formed at the position where the fold curve 8 is formed. Wrinkles may be formed. On the other hand, in the napkin 1, the presence of the fiber mass 11S straddling the fold curve as shown in FIGS. 7 (a) and 7 (b) cuts off the hydrophilic fiber layer and is continuous over the entire length of the fold curve 8. Is hindered.

In order to ensure that the fiber mass 11S straddling the folding curve is present in the absorbent core 40, it is preferable that the fiber mass 11 is uniformly dispersed over the entire surface direction of the absorbent core 40, and is absorbent. It is more preferable that the core 40 is uniformly dispersed throughout the core 40. Further, the relatively large fiber mass 11 (the maximum transfer length is relatively long) is also advantageous in ensuring that the fiber mass 11S straddles the folding curve in the absorbent core 40 (this point). Will be described later).

Further, even if the fiber lump 11S straddling the fold curve exists in the portion of the absorbent core 40 that overlaps the fold curve 8 in the thickness direction, if all the fiber lumps 11 existing in the portion are fused to each other, the fiber lumps 11 may be fused. Since the rigidity of the portion is increased, the napkin is easily broken so as to avoid the fused fiber mass 11, and there is a possibility that the folding curve 8 cannot be crossed as shown in FIG. 7 (d). Furthermore, the folding is not stable as designed, which is not preferable in manufacturing. However, in the napkin 1, such a concern is dispelled because there is a portion where the fiber lumps 11 are not fused to each other in the portion of the absorbent core 40 that overlaps with the folding curve 8 in the thickness direction.

In the napkin 1, as shown in FIG. 1, a part of the folding curve 8 and the recessed portion 7 overlap in the thickness direction, and the recessed portion in the portion of the absorbent core 40 that overlaps with the overlapping portion in the thickness direction. Due to the forming method of 7, the fiber lumps 11 may be fused to each other. However, the ratio of the area of the overlapping portion with the recessed portion 7 to the total area of the folding curve 8 in the plan view is small, and specifically, it is usually about 10% or less. That is, most of the portion of the absorbent core 40 that overlaps the folding curve 8 in the thickness direction (the portion other than the portion that overlaps the recessed portion 7 in the thickness direction) is entangled with the fiber lumps 11 without being fused.

From the viewpoint of more reliably preventing the occurrence of creases due to individual packaging, the fiber mass 11S straddling the fold curve is
As shown in FIGS. 7 (a) and 7 (b), not only the fold curve 8 but also the crease 80 formed along the fold curve 8 may be straddled in a direction intersecting the extending direction thereof. preferable. As shown in FIG. 7A, "straddling the crease in the direction intersecting the extending direction" here means that one fold curve straddling fiber mass 11S straddles the crease 80 only. Instead, as shown in FIG. 7B, there is a form in which a plurality of (two in the illustrated form) fold curve straddling fiber lumps 11S adjacent to the extending direction of the fold curve 8 straddle the crease 80 as a whole. Be included.

In the form shown in FIG. 7B, a folded curve straddling fiber mass 11S straddling only one of both side edges along the extending direction (longitudinal direction X) of the crease 80 and a folded curve straddling fiber mass straddling only the other side. Since at least a part of the 11S is in the same position in the thickness direction of the absorbent core 40 and is arranged close to the 11S in the extending direction, apparently one fold curve straddling fiber mass 11S is formed in the crease 80. It straddles both sides of the edge. Therefore, the effect of preventing the occurrence of wrinkles due to individual packaging, which is exhibited by the form shown in FIG. 7 (b), is substantially comparable to that produced by the form shown in FIG. 7 (a). In the form shown in FIG. 7B, the distance between the plurality of fold curve straddling fiber lumps 11S adjacent to the fold curve 8 in the extending direction is preferably within 30 mm from the viewpoint of surely preventing the occurrence of creases. More preferably, it is within 10 mm.

However, from the viewpoint of more reliably preventing the occurrence of creases due to individual packaging, as shown in FIG. 7A, the fold curve straddling fiber mass 11S straddles the crease 80 in the direction intersecting the extending direction thereof. It is preferable to include one fiber mass 11S. In other words, it is preferable that the fold curve straddling fiber mass 11S contains at least one having a size capable of straddling the crease 80 in the direction intersecting the extending direction thereof.

From the same viewpoint, the maximum transfer length of the basic surface 111 (the length indicated by the reference numeral L2 in FIG. 5) in the fiber mass 11S straddling the fold curve is the extending direction of the crease 80 formed along the fold curve 8. It is preferably longer than the length in the orthogonal direction (vertical direction X in the illustrated form). Further, with such a configuration, the fiber mass 11S straddling the folding curve can be more reliably present in the absorbent core 40.

In order to effectively prevent the occurrence of creases due to individual packaging, the number of fiber lumps 11S straddling the fold curve is required to some extent. From such a viewpoint, the number of the folded curve straddling fiber lumps 11S existing in an arbitrary 50 mm ³ cubic region at the portion overlapping the folded curve 8 in the absorbent core 40 in the thickness direction is preferably 3 or more, more preferably 5. More than one. The number of fiber lumps 11S straddling the fold curve is measured by, for example, the following method. That is, the absorbent core 40 is taken out from the absorbent article to be measured, for example, the napkin 1, and the length of the folded curve 8 in the extending direction is 50 mm from the portion of the absorbent core 40 that overlaps with the folded curve 8 in the thickness direction. A length of 1 mm and a depth of 1 mm in a direction orthogonal to the extending direction may be cut out to obtain a measurement sample, and the measurement sample may be visually observed and the number of fiber lumps 11 contained therein may be counted.

In the napkin 1, as shown in FIG. 1, where the folding curve 8 crosses the napkin 1 in the lateral direction Y, the napkin 1 folds outward of the vertical direction X of the folding curve 8 (crease 80). It has a high rigidity region 45 having a bending rigidity higher than that of the curve 8 (crease 80). More specifically, in the napkin 1, a high-rigidity region 45 having an oblong shape in a plan view is located in the central portion of the vertical central region B in the horizontal direction Y, which is a region sandwiched between the two folding curves 8 and 8. However, the major axis direction is aligned with the vertical direction X. Further, the rear side of the vertical direction X from the folding curve 8 extending in the lateral direction Y through the roots of the pair of wing portions 5W and 5W near the rear region C, specifically, the center of the lateral direction Y of the rear region C. Another high-rigidity region 45 having an oblong shape in a plan view is arranged in the portion so that its major axis direction coincides with the vertical direction X.

In this way, the napkin 1 is more rigid than the fold curve 8 (crease 80) in the outward direction in the direction orthogonal to the extending direction of the fold curve 8 (crease 80), close to the fold curve 8 (crease 80). By arranging the high-rigidity region 45 of the above, when the napkin 1 is folded into the individual package 10, the napkin 1 is preferentially bent at the folding curve 8. That is, the high-rigidity region 45 functions as a bending guide portion that bends the napkin 1 along the folding curve 8 as designed.

In the high-rigidity region 45 of the napkin 1, as shown in FIG. 1, a plurality of high-rigidity portions 46 are intermittently arranged. The high-rigidity portion 46 is typically formed by subjecting a known position of the high-rigidity region 45 in the absorbent core 40 to a known pressing process such as heat-embossing or ultrasonic embossing. In the high-rigidity portion 46 due to the forming method, the fiber lumps 11 existing therein are fused to each other to form a fused portion. Further, the high-rigidity portion 46 formed by such squeezing processing has a higher density than the other portion (non-squeezing portion) of the absorbent core 40 which has not been squeezed. The pressing process for forming the high-rigidity portion 46 may be performed from the skin facing surface side of the absorbent core 40, or may be performed from the non-skin facing surface side.

As the high-rigidity region 45 in which the high-rigidity portion 46 which is a squeezing portion between the fiber lumps 11 is present, the flexibility of the absorbent core 40 and the certainty of the folding position, that is, the folding curve 8 is surely set at a predetermined position. From the viewpoint of compatibility with the formation of the above, a form in which a plurality of high-rigidity portions 46 (squeezed portions) are intermittently arranged as shown in FIG. 1 is preferable. In the high-rigidity region 45 shown in FIG. 1, a plurality of high-rigidity portions 46 (squeezed portions) are surrounded by low-rigidity portions (non-squeezed portions) having lower rigidity, whereby the high-rigidity region 45 Compared with the case where the entire area of the high-rigidity portion 46 is a high-rigidity portion 46, the flexibility, cushioning property, and the like are high.

In the form shown in FIG. 1, a plurality of high-rigidity portions (squeezed portions) 46 having a circular shape in a plan view are arranged in a staggered manner, but the pattern (shape and arrangement in a plan view) of the high-rigidity portions 46 is not limited to this. .. For example, as the plan view shape of the high-rigidity portion 46, in addition to the circular shape as shown in the figure, an elliptical shape, a quadrangular or rhombic shape, a polygonal shape having a pentagon or more, and the like can be mentioned.

Although the present invention has been described above based on the embodiment, the present invention can be appropriately modified without being limited to the embodiment.
For example, in the above embodiment, the absorber 4 is configured to include the absorbent core 40 and the core wrap sheet 41 covering the absorbent core 40, but the core wrap sheet 41 may be omitted.
Further, in the absorbent core according to the present invention, all of the fiber lumps (synthetic fiber aggregates) contained therein do not have to be a fixed-shaped fiber aggregate such as the fiber lump 11, which deviates from the gist of the present invention. As long as it does not, a very small amount of atypical fiber aggregates may be contained in addition to the fixed-form fiber aggregates.
The absorbent article of the present invention broadly includes articles used for absorbing body fluids (urine, loose stool, menstrual blood, sweat, etc.) discharged from the human body, and in addition to the above-mentioned menstrual napkins, sanitary shorts and fastenings. So-called deployable disposable diapers with tape, pants-type disposable diapers, incontinence pads and the like are included.

1 Menstrual napkin (absorbent article)
A Front area B Vertical center area C Rear area 2 Front sheet 3 Back sheet 4 Absorber 40 Absorbent core 11 Fiber mass 11S Folded curve straddling fiber mass 11F Fiber mass constituent fibers (synthetic fiber)
110 Main body 111 Basic surface 112 Skeleton surface 12F Hydrophilic fiber 41 Core wrap sheet 45 High rigidity region 46 High rigidity part 5 Absorbent main body 7 Recessed part 8 Folded curve 80 Fold 10 bs Fiber mass raw material fiber sheet 10 pieces

Claims (7)

An absorbent body including an absorbent core and a surface sheet arranged on the skin-facing surface side of the absorbent body are provided, and the absorbent body has a vertical direction corresponding to the front-back direction of the wearer and a horizontal direction orthogonal to the vertical direction. It ’s an article,
The absorbent core contains a fiber mass containing synthetic fibers and a hydrophilic fiber, and the fiber masses or the fiber mass and the hydrophilic fiber are entangled with each other.
The fiber mass comprises two opposing basic surfaces and a skeletal surface connecting the two basic surfaces.
On the skin-facing surface of the surface sheet, a folding curve used for folding the absorbent article with the surface sheet inside extends in a predetermined direction.
In the portion of the absorbent core that overlaps the folding curve in the thickness direction, there is a fiber mass straddling the folding curve that straddles the folding curve in the direction intersecting the extending direction thereof, and all contained in the absorbent core. The fiber lumps of the above are entangled with each other without being fused, or
A concave portion in which the surface sheet and the absorbent core are integrally recessed on the non-skin facing surface side of the absorbent core is formed on the skin facing surface of the absorbent article, and a part of the folding curve is formed. When the recessed portion overlaps in the thickness direction, the fiber lumps in the portion overlapping the recessed portion in the thickness direction in the absorbent core are fused to each other, and the recessed portion in the absorbent core and the thickness direction are fused. The fiber lumps in the parts other than the overlapping parts are entangled without being fused .
An absorbent article including a portion in which the fiber lumps straddling the folding curve are entangled without being fused . The first aspect of the present invention, wherein the folding curve traverses the absorbent article in the lateral direction, and has a high rigidity region having a bending rigidity higher than that of the folding curve at the outside in the vertical direction of the folding curve. Absorbent article. The absorbent article according to claim 2, wherein the high-rigidity portion is present in the high-rigidity region. The absorbent article according to claim 2 or 3, wherein a plurality of high-rigidity portions are intermittently arranged in the high-rigidity region. The absorbent article according to any one of claims 1 to 4, wherein the folding curve is present in each of the front and rear in the vertical direction with the excretion portion facing portion arranged opposite to the wearer's excretion portion. Any of claims 1 to 5, wherein the maximum transfer length of the basic surface in the fiber mass straddling the fold curve is longer than the length in the direction orthogonal to the extending direction of the fold formed along the fold curve. Or the absorbent article according to item 1. The one according to any one of claims 1 to 6, wherein the fiber mass straddling the folding curve includes one fiber mass straddling the crease formed along the folding curve in a direction intersecting the extending direction thereof. Absorbent article.

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