JP2020163005A - Absorbent article - Google Patents

Abstract

To provide an absorbent article which is hardly twisted in wearing, shows excellent in wearing feeling, and is excellent in liquid absorptivity.SOLUTION: In an absorbent core 40, a groove-like recessed part 42 which has an opening at least in one of a skin facing surface 45 and a non-skin facing surface 46 of the absorbent core 40 and extends in a prescribed direction is formed. A part overlapped with the groove-like recessed part 42 in a plane view in the absorbent core 40 has a lower basis weight compared to the periphery. The absorbent core 40 includes a fiber lump 11 containing a synthetic resin 11F and a water absorptive fiber 12F.SELECTED DRAWING: Figure 2

Description

The present invention relates to absorbent articles such as sanitary napkins.

Absorbent articles such as disposable diapers and sanitary napkins generally include a front sheet that is relatively close to the wearer's skin and a back sheet that is relatively far from the wearer's skin. , Consists of an absorber interposed between the two sheets. This absorber is typically composed of an absorbent core containing a water-absorbent fiber such as wood pulp or a water-absorbent material such as a water-absorbent polymer, and further, a core wrap sheet that covers the outer surface of the absorbent core. Is often configured to include. For the absorber used in the absorbent article, improvement of various properties such as flexibility, cushioning property, compression recovery property, and shape retention property is a big issue.

As a technique for improving the absorber, for example, Patent Document 1 describes an absorber containing a thermoplastic resin fiber and a cellulosic water-absorbent fiber, and the thermoplastic resin fiber is the surface of the absorber on the surface sheet side. And those exposed on both the front surface of the absorber on the back sheet side 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 hard to twist. .. Further, Patent Document 1 describes an absorbent article provided with this absorber having a concave embossed portion formed by embossing from the surface sheet side, and further, in the embossed portion, a thermoplastic resin. It is stated that it is preferable that the fiber is fused with another fiber. The embossed portion described in Patent Document 1 is known as a leak-proof groove or the like in the present technical field, and is used for an absorbent article for the purpose of improving liquid diffusivity and shape retention in the plane direction. Has been done.

Patent Document 2 describes a non-woven fabric piece containing heat-sealing fibers and having a three-dimensional structure formed by bonding the fibers in advance, and an absorber containing water-absorbent fibers, and the non-woven fabric piece absorbs. It is evenly distributed throughout the body. 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 due to such a manufacturing method, FIGS. 1 and 1 and FIGS. 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. Patent Document 2 describes a preferred form of the absorber described in the same document in which non-woven fabric pieces are heat-sealed together. According to the absorber described in Patent Document 2, since the non-woven fabric piece has a three-dimensional structure, voids are formed inside the absorber, and the resilience when absorbing moisture is improved, and as a result, the water absorption performance is improved. It is said that.

In Patent Document 3, the absorbent core of the absorbent article has a groove-shaped recess having an opening on the non-skin facing surface side of the absorbent core and extending in both the vertical and horizontal directions, and the recess. A recess absorbing portion containing pulp fibers is provided at the bottom of the skin facing surface side, and the area surrounded by the recess and the recess absorbing portion is used as a block-shaped protruding absorbing portion protruding toward the non-skin facing surface side. It is described that the protruding absorbing portion contains a pulp fiber and a water-absorbing polymer. In the absorbent article described in Patent Document 3, since the absorbent core is divided into a plurality of block-shaped protruding absorbing portions by groove-shaped recesses intersecting with each other, the body fluid excreted by the wearer is the absorbent core. While diffusing in the surface direction on the skin-facing surface side, it is quickly drawn into the absorbent core and absorbed and held by the block-shaped protruding absorbing portion. Therefore, according to the absorbent article described in Patent Document 3, it is said that the excellent liquid absorbency suppresses liquid residue and liquid return to the surface sheet.

Japanese Unexamined Patent Publication No. 2015-16296 JP-A-2002-301105 Japanese Unexamined Patent Publication No. 2012-130363

The absorber described in Patent Document 1 further contains synthetic fibers (thermoplastic resin fibers) in addition to the cellulosic water-absorbent fibers, but a plurality of synthetic fibers contained therein are present independently. It does not form a single mass. Therefore, the absorber described in Patent Document 1 does not have sufficient cushioning property, compression recovery property, etc., and therefore, when applied to an absorbent article, it may be easily twisted and the fit may be insufficient. After absorption of body fluids such as urine and menstrual blood, the occurrence of such inconvenience is remarkable.

On the other hand, in the absorber described in Patent Document 2, the synthetic fibers contained are synthetic fiber aggregates called non-woven fabric pieces. As described above, the non-woven fabric mainly composed of synthetic fibers is crushed into fine pieces. Alternatively, since it is manufactured by peeling or tearing it off, it has an indefinite shape and the shape and size are not uniform, and due to this, when mixed with wood pulp etc., both It is difficult to obtain a uniform mixture, and the desired effect may not be obtained.

Further, from the viewpoint of improving the shape retention of the absorber, as described in Patent Document 2, when all the synthetic fiber aggregates contained in the absorber are heat-sealed to each other, the absorber becomes flexible. The property, cushioning property, etc. are impaired, and the improvement of the fit of the absorbent article becomes insufficient. An absorbent article comprising an absorber containing a synthetic fiber aggregate, which is hard to be twisted when worn, has a good wearing feeling, and has excellent liquid absorbability, has not yet been provided.

Therefore, an object of the present invention is to provide an absorbent article which is hard to be twisted when worn, has a good wearing feeling, and is excellent in liquid absorption.

The present invention has a vertical direction corresponding to the front-back direction of the user and a horizontal direction orthogonal to the vertical direction, and in the vertical direction, a vertical central region arranged to face the excretory portion of the user and the vertical central region. It is an absorbent article having an anterior region arranged on the front side in the vertical direction and a rear region arranged on the rear side in the vertical direction with respect to the vertical central region, and having an absorbent core for absorbing and holding body fluid. The absorbent core is formed with a groove-like recess having an opening in at least one of the skin-facing surface and the non-skin-facing surface of the absorbent core and extending in a predetermined direction. The portion of the core that overlaps the groove-shaped recess in a plan view has a lower basis weight than the periphery thereof, and the absorbent core is an absorbent article containing a fiber mass containing synthetic fibers and a water-absorbent fiber. Is.

The absorbent article of the present invention is not easily twisted when worn, has a good wearing feeling, and is excellent in liquid absorption.

FIG. 1 is a plan view schematically showing 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 schematic cross-sectional view of the cross section taken along line II of FIG. FIG. 3 is a schematic perspective view of an embodiment of the surface sheet included in the absorbent article shown in FIG. FIG. 4 is a schematic plan view of the absorbent body provided in the absorbent article shown in FIG. 1 on the skin-facing surface side. FIG. 5 is a schematic cross-sectional view of the cross section taken along line II-II of FIG. FIG. 6 is a schematic cross-sectional view (corresponding to FIG. 5) of another embodiment of the absorber according to the present invention. FIG. 7 is a schematic cross-sectional view (corresponding to FIG. 5) of still another embodiment of the absorber according to the present invention. FIG. 8 is a schematic cross-sectional view (corresponding to FIG. 5) of still another embodiment of the absorber according to the present invention. FIG. 9 is a schematic plan view (corresponding to FIG. 4) of the absorber according to the present invention on the skin-facing surface side of still another embodiment. FIG. 10 is a schematic plan view (corresponding to FIG. 4) of the absorber according to the present invention on the skin-facing surface side of still another embodiment. FIG. 11 is a schematic plan view (corresponding to FIG. 4) of the absorber according to the present invention on the skin-facing surface side of still another embodiment. 12 (a) and 12 (b) are schematic perspective views of the fiber mass according to the present invention, respectively. FIG. 13 is an explanatory diagram of a method for producing a fiber mass according to the present invention. FIG. 14 (a) is an electron micrograph (observation magnification 25 times) of the fiber mass according to the present invention, and FIG. 14 (b) is a diagram schematically showing the fiber mass of the electron micrograph.

Hereinafter, the present invention will be described based on the preferred embodiment with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar reference numerals. The drawings are basically schematic, and the ratio of each dimension may differ from the actual one.

1 and 2 show a sanitary napkin 1, which is an embodiment of the absorbent article of the present invention. The napkin 1 is an article used to absorb body fluids such as menstrual blood excreted by the user, that is, the wearer, and is an absorber 4 having an absorbent core 40 that absorbs and retains the body fluids, and the absorber 4. A liquid-permeable front surface sheet 2 arranged on the skin-facing surface side of the body 4 and capable of contacting the wearer's skin, and a leak-proof back surface sheet 3 arranged on the non-skin-facing surface side of the absorber 4. To do. As shown in FIG. 1, the napkin 1 has a longitudinal direction X extending from the ventral side of the wearer to the dorsal side via the crotch portion and a lateral direction Y orthogonal to the longitudinal direction X corresponding to the front-back direction of the wearer. In the vertical direction X, the vertical central region M including the excretion portion facing portion (excretion point) facing the excretion portion such as the wearer's vaginal opening, and the ventral side (anterior side) of the wearer from the excretion portion facing portion. ), And the rear region R, which is located on the back side (rear side) of the wearer from the portion facing the excretion portion.

In the present specification, the "skin facing surface" is a surface of the absorbent article or its constituent members (for example, the absorber 4) that is directed toward the skin side of the wearer when the absorbent article is worn, that is, relatively of the wearer. The side closer to the skin, the "non-skin facing surface" is the side of the absorbent article or its constituents that is opposite to the skin side when the absorbent article is worn, that is, toward the side relatively far from the wearer's skin. It is the surface to be. The term "when worn" as used herein means a state in which the normal proper wearing position, that is, the correct wearing position of the absorbent article is maintained.

As shown in FIG. 1, the napkin 1 has an absorbent main body 5 having a shape long in the vertical direction X and both side portions of the absorbent main body 5 along the vertical direction X in the vertical central region M toward the outside in the horizontal direction Y. It has a pair of extending wing portions 5W and 5W. The absorbent main body 5 is a portion that forms the main body of the napkin 1, includes the front surface sheet 2, the back surface sheet 3, and the absorber 4, and has a front region F, a vertical center region M, and a rear region R 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 drawing) of the absorbent article when the absorbent article has a wing portion as in the napkin 1. It corresponds to a region having a portion, and taking the 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. In the napkin 1, the pair of wing portions 5W and 5W are formed symmetrically with respect to the vertical center line extending in the vertical direction X by dividing the napkin 1 into two in the horizontal direction Y, and one wing portion 5W. The base on the side closer to the front region F and that of the other wing portion 5W are located at the same position in the vertical direction X. Further, the vertical central region of an absorbent article having no wing portion (for example, a disposable diaper) corresponds to a region located in the middle when the absorbent article is divided into three equal parts in the vertical direction.

In the napkin 1, the absorber 4 is composed of a liquid-absorbing 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 in 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. As shown in FIG. 1, the absorber 4 (absorbent core 40) extends substantially the entire length of the napkin 1 (absorbent body 5) in the vertical direction X, and extends from the front region F to the rear region R via the vertical center region M. It extends over. The absorbent core 40 and the core wrap sheet 41 may be bonded by an adhesive such as a hot melt type adhesive.

The core wrap sheet 41 may be 1) composed of only one sheet, or 2) may be composed of a plurality of sheets. The core wrap sheet 41 of 1) is, for example, 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 is opposed to the skin of the absorbent core 40. It covers the entire surface 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 is wound down below the absorbent core 40 to absorb. It covers the entire non-skin facing surface of the sex core 40. The core wrap sheet 41 of 2) is, for example, a single skin-side core wrap sheet that covers the skin-facing surface of the absorbent core 40, and the skin-side core wrap sheet that is separate from the skin-side core wrap sheet, and is a separate body of the absorbent core 40. It is composed of two sheets including one non-skin side core wrap sheet that covers the non-skin facing surface.

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 from both side edges along the vertical direction X of the absorber 4 in the horizontal direction Y, together with the side sheet 6 described later. A side flap portion is formed. 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 sanitary napkins can be used without particular limitation. As the surface sheet 2, for example, a liquid-permeable single-layer or multi-layered non-woven fabric can be used, and as the non-woven fabric, a non-woven fabric manufactured by the card method, a spunbonded non-woven fabric, a melt-blown non-woven fabric, a spunlaced non-woven fabric, and a needle Punched non-woven fabric can be exemplified. The non-woven fabric constituting the surface sheet 2 may be subjected to a hydrophilization treatment using a hydrophilizing agent such as a surfactant. The back sheet 3 is a leak-proof sheet, that is, liquid impermeable (property that does not allow liquid to pass through at all) or liquid impermeability (property that does not allow liquid to pass through, although it cannot be said to be liquid impervious). A sheet having the above can be used, and for example, a moisture-permeable resin film can be used.

In the present embodiment, as shown in FIG. 2, the surface sheet 2 has a plurality of convex portions 21 protruding toward the skin side of the wearer on the skin facing surface. A concave portion 22 is formed around the convex portion 21, and a concave-convex shape composed of a plurality of convex portions 21 and the concave portion 22 is provided on the skin-facing surface of the surface sheet 2. The uneven shape of the skin-facing surface is present at least on the skin-facing surface of the surface sheet 2 at a portion that can come into contact with the wearer's skin when the napkin 1 is worn, and may be present over the entire skin-facing surface. .. Such a surface sheet having an uneven shape on the surface (concave and convex surface sheet) is typically pressed by embossing or the like on a raw sheet (a manufacturing intermediate of a surface sheet having no unevenness). It can be manufactured by partially applying it, and the portion of the uneven surface sheet that has been pressed is the concave portion 22, and the portion that has not been pressed is the convex portion 21. The concave portion 22 has a higher density than the convex portion 21 in which the material for forming the surface sheet 2 is compacted by the pressing process and is not subjected to the pressing process.

The surface sheet 2 which is an uneven surface sheet has a plurality of convex portions 21 formed on the skin facing surface so as to project toward the wearer's skin side, and the uneven skin facing surface is the same as the skin of the wearer of the napkin 1. When they come into contact with each other, the top of the convex portion 21 and the region in the vicinity thereof partially come into contact with each other, so that the skin-facing surface of the surface sheet 2 is in full contact with the skin, resulting in stickiness, stuffiness, and rubbing. The resulting irritation is reduced. In addition, the liquid excreted from the wearer is less likely to adhere to the wearer's skin, and an unpleasant wet feeling is reduced.

The formation pattern (shape and arrangement of the convex portions) of the convex portion 21 on the skin-facing surface of the surface sheet 2 is not particularly limited, and the pattern on the uneven surface sheet in this type of absorbent article can be appropriately adopted. FIG. 3 shows a surface sheet 2A, which is an embodiment of an uneven surface sheet applicable to the present invention.

As shown in FIG. 3, the surface sheet 2A has two layers having a skin-side fiber layer 23 located on the side closer to the wearer's skin and a non-skin-side fiber layer 24 located on the side far from the wearer's skin. It is a non-woven fabric having a structure, and both fiber layers 23 and 24 are integrated in the thickness direction Z by a large number of partially formed joints 25, and are located between the plurality of joints 25 in the skin side fiber layer 23. The portion to be formed is raised in a convex shape to form a solid convex portion 21 on the skin facing surface side, and the portion other than the convex portion 21 including the joint portion 25 is the concave portion 22. The convex portion 21 of the solid structure includes two types of convex portions 21A and 21B having different sizes. The large convex portion 21A has a higher height and a larger area in a plan view than the small convex portion 21B. Both the convex portions 21A and 21B have a circular shape in a plan view, and also have a shape having a top in a cross section in either the vertical direction X or the horizontal direction Y. The two convex portions 21A and 21B are alternately arranged in a direction intersecting both the vertical direction X and the horizontal direction Y. Further, a plurality of large convex portions 21A are intermittently arranged at predetermined intervals in the lateral direction Y to form a large convex portion row, and a plurality of small convex portions 21B are intermittently arranged at predetermined intervals in the lateral direction Y. They are arranged to form a row of small and large convex portions, and the row of large convex portions and the row of small convex portions are alternately arranged in the vertical direction X. The joint portion 25 is formed by embossing with heat and has an X-shape or a Y-shape in a plan view.

In the surface sheet 2A, the skin-side fiber layer 23 is a non-woven fabric mainly composed of non-heat-shrinkable fibers, and the non-skin-side fiber layer 24 is a non-woven fabric mainly composed of heat-shrinkable fibers. As the non-heat-shrinkable fiber mainly composed of the skin-side fiber layer 23, a fiber having substantially no heat-shrinkability or a fiber having a heat-shrinkable temperature higher than that of the heat-shrinkable fiber can be used. As the heat-shrinkable fibers that mainly form the non-skin side fiber layer 24, those made of a thermoplastic polymer material and having heat-shrinkability are preferably used. Examples of such fibers include latent crimp fibers. Before being heated, the latent crimpable fibers can be handled in the same manner as conventional fibers for non-woven fabrics, and when heated at a predetermined temperature, spiral crimps are developed and contracted. It is a fiber to have. The content ratio of the heat-shrinkable fiber in the non-skin side fiber layer 24 is preferably 40% by mass or more and 100% by mass or less. The latent crimpable fiber is composed of, for example, an eccentric core sheath type or side-by-side type composite fiber containing two types of thermoplastic polymer materials having different shrinkage rates. Examples thereof include those described in JP-A-9-296325 and Japanese Patent No. 2759331. The non-skin side fiber layer 24 is, for example, at the time when the fiber layer containing the latent crimp fiber is heat-sealed with the skin side fiber layer 23, or after the heat fusion, the latent crimp fiber is rolled by heating. It is formed by expressing contraction and contracting it. As the uneven non-woven fabric having two or more kinds of convex portions having different sizes on the surface facing the skin, such as the surface sheet 2A, for example, those described in JP-A-2015-186543 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 M, 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 provided with a wing portion adhesive portion (not shown) as a fixing means for fixing the wing portion 5W to clothes such as shorts. Since 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, the non-skin facing surface of the wing portion 5W, which is the forming surface of the wing portion adhesive portion, is used. At the time of its use, it is directed toward the wearer's skin side and becomes a skin facing surface. Further, on the non-skin facing surface of the absorbent main body 5, that is, the non-skin facing surface of the back sheet 3, a main body adhesive portion (not shown) as a fixing means for fixing the napkin 1 (absorbent main body 5) to clothes such as shorts. ) Is provided. Before its use, the wing adhesive portion and the main body adhesive portion are each 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 is overlapped with the left and right side portions of the absorber 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 at a joining line (not shown) extending in the vertical direction X, respectively.

4 and 5 show the absorber 4 included in the napkin 1. The absorbent core 40 included in the absorber 4 has a groove-shaped recess 42 having an opening in at least one of the skin facing surface 45 and the non-skin facing surface 46 of the absorbent core 40 and extending in a predetermined direction. It is formed. The groove-shaped recess 42 is preferably a space portion in which the material (core forming material) constituting the absorbent core 40 does not exist, but a small amount of core forming material may be present so that the space portion can be recognized. ..

The groove-shaped recess 42 includes a non-penetrating type that does not penetrate the absorbent core 40 in the thickness direction (see FIGS. 5 to 7) and a penetrating type that penetrates the absorbent core 40 in the thickness direction (see FIG. 8). Is included. The groove-shaped recess 42 in the absorber 4 is the former, and as shown in FIG. 5, has an opening on the non-skin facing surface 46 of the absorbent core 40 and has a bottom on the side opposite to the opening. The bottom portion of the groove-shaped recess 42 is a portion that overlaps the groove-shaped recess 42 in a plan view of the absorbent core 40 (projection view in the thickness direction of the absorbent core 40), and is configured to include a core forming material. On the other hand, the through-type groove-shaped recess 42 does not have a bottom portion, and the portion of the absorbent core 40 that overlaps with the through-type groove-shaped recess 42 in a plan view is a space portion, which is a so-called through hole.

In the absorbent core 40, the portion overlapping the groove-shaped recess 42 in a plan view has a lower basis weight than the periphery thereof (specifically, the small absorbing portion 43 described later), that is, a unit of the core forming material compared to the periphery. Low mass per area. In the case of "low basis weight" here, unlike the through-type groove-shaped recess 42, there is no core forming material in the portion overlapping the groove-shaped recess 42 in a plan view, and the basis weight of the portion is zero. Including the case.

In the absorber 4, as shown in FIG. 4, the groove-shaped recess 42 has a vertical recess 42X extending in the vertical direction X and a horizontal recess 42Y extending in a direction intersecting the vertical recess 42X, and has an absorbent core. The surface side of 40 in which the opening of the vertical recess 42X and the opening of the horizontal recess 42Y are formed is divided into a plurality of small absorbing portions 43. More specifically, in the absorber 4, a plurality of vertical recesses 42X are intermittently arranged in the horizontal direction Y, and a plurality of horizontal recesses 42Y are intermittently arranged in the vertical direction X, so that the plurality of vertical recesses 42X are arranged intermittently. And the plurality of lateral recesses 42Y are orthogonal to each other. The plurality of vertical recesses 42X are continuous from one end to the other end of the absorbent core 40 in the vertical direction X, and the plurality of horizontal recesses 42Y are continuous from one end to the other end of the absorbent core 40 in the horizontal direction Y, respectively. are doing. Further, all the groove-shaped recesses 42 (vertical recesses 42X, horizontal recesses 42Y) formed in the absorbent core 40 have openings in the non-skin facing surface 46 of the absorbent core 40. Therefore, in the absorber 4, the non-skin facing surface 46 side of the absorbent core 40 is divided into a plurality of small absorbing portions 43 by a plurality of vertical recesses 42X and horizontal recesses 42Y orthogonal to each other, and each small absorbing portion 43 is divided into a plurality of small absorbing portions 43. It has a quadrangular shape in a plan view as shown in FIG.

In the absorber 4, as shown in FIG. 5, the absorbent core 40 is partly in the thickness direction of the absorbent core 40, and the entire area in the plane direction (direction orthogonal to the thickness direction) of the absorbent core 40. It has a continuous layer 44 in which the groove-shaped recess 42 is not formed. The portion of the continuous layer 44 that overlaps the groove-shaped recess 42 (vertical recess 42X, lateral recess 42Y) in a plan view (that is, a projection view in the thickness direction of the absorber 4) constitutes the bottom of the non-penetrating groove-shaped recess 42. To do. The plurality of small absorption portions 43 are integrated via the continuous layer 44.

Further, in the absorber 4, as shown in FIG. 5, the continuous layer 44 is unevenly distributed on the skin facing surface 45 side of the absorbent core 40. As a result, the skin-facing surface 45 of the absorbent core 40 is formed by the continuous layer 44, and is a flat surface having substantially no unevenness. On the other hand, the non-skin facing surface 46 of the absorbent core 40 has a concave-convex shape composed of a concave portion formed by an opening of the groove-shaped concave portion 42 and a convex portion formed of a small absorbing portion 43, and is a concave-convex surface.

Since the groove-shaped recess 42 in the absorbent core 40 has no or little core-forming material, it is likely to be a starting point of bending. Further, in the portion that overlaps the groove-shaped recess 42 in a plan view (hereinafter, also referred to as “the existing portion of the groove-shaped recess 42”), when the groove-shaped recess 42 is a non-penetrating type, the core forming material is more than the surrounding portion. When the small portion, the groove-shaped recess 42 is a through type, it is a space portion where the core forming material does not exist, and regardless of the type of groove-shaped recess 42, the non-existing portion (small absorption portion) of the groove-shaped recess 42 The rigidity is lower than that of 43), and therefore, when the napkin 1 is worn, it easily becomes a flexible shaft when the absorbent core 40 bends, and can act as a bending guide portion. Therefore, when the napkin 1 is worn, the absorbent body 4 (absorbent core 40) can be deformed along the body shape of the wearer by using the groove-shaped recess 42 as a bending guide portion. Therefore, the napkin 1 has excellent fit, gives the wearer a good wearing feeling, and can effectively suppress leakage of body fluid such as menstrual blood. Further, since the groove-shaped recess 42 extends in the vertical direction X and the horizontal direction Y in the absorbent core 40, the absorption time of the body fluid is shortened as compared with the case where the groove-shaped recess 42 is not formed. At the same time, the diffusivity of the body fluid in the surface direction is improved, and the liquid absorbency of the napkin 1 can be improved.

As described above, the groove-shaped recess 42 may have an opening in at least one of the skin-facing surface 45 and the non-skin-facing surface 46 of the absorbent core 40 and extend in a predetermined direction, and the arrangement and shape thereof are shown in FIG. It is not limited to the form shown in 4 and 5. 6-8 show other embodiments of the absorber that can be employed in the present invention. Regarding other embodiments described later, components different from those of the embodiment (absorbent 4) will be mainly described, and similar components will be designated by the same reference numerals and description thereof will be omitted. The description of the embodiment is appropriately applied to the components not particularly described. In the following, the embodiments of the absorber according to the present invention, such as the absorbers 4A to 4F, are collectively referred to as "absorbent 4".

In the absorber 4A shown in FIG. 6, the groove-shaped recess 42 is a non-penetrating type that does not penetrate the absorbent core 40 in the thickness direction, has an opening in the skin facing surface 45 of the absorbent core 40, and has an opening. It has a bottom on the opposite side of the opening. Further, in the absorber 4A, the continuous layer 44 is unevenly distributed on the non-skin facing surface 46 side of the absorbent core 40. Therefore, in the absorber 4A, the skin facing surface 45 has a concave-convex shape composed of a concave portion formed by the opening of the groove-shaped concave portion 42 and a convex portion formed of the small absorbing portion 43, and is a concave-convex surface and is a non-skin facing surface. Reference numeral 46 denotes a flat surface formed by the continuous layer 44 and having substantially no unevenness.

In the absorber 4B shown in FIG. 7, the groove-shaped recess 42 is a non-penetrating type that does not penetrate the absorbent core 40 in the thickness direction, and the skin-facing surface 45 and the non-skin facing surface 46 of the absorbent core 40. It has openings on both sides and a bottom on the opposite side of the openings. Further, in the absorber 4B, the continuous layer 44 is unevenly distributed in the central portion in the thickness direction of the absorbent core 40. Therefore, in the absorber 4B, the skin facing surface 45 and the non-skin facing surface 46 both have a concave-convex shape composed of a concave portion formed by the opening of the groove-shaped concave portion 42 and a convex portion formed by the small absorbing portion 43, and have unevenness. It is a face. In the absorber 4B, the groove-shaped recess 42 having an opening on the skin facing surface 45 and the groove-shaped recess 42 having an opening on the non-skin facing surface 46 overlap in a plan view (projected view in the thickness direction of the absorber 4B). .. Similarly, the small absorbing portion 43 on the skin facing surface 45 side and the small absorbing portion 43 on the non-skin facing surface 46 side overlap each other in a plan view.

In the absorber 4C shown in FIG. 8, the groove-shaped recess 42 is a penetrating type that penetrates the absorbent core 40 in the thickness direction and does not have a bottom. Therefore, the absorber 4C does not have the continuous layer 44, and the plurality of small absorbers 43 are separably and independently present. In the absorber 4C, the plurality of small absorbent portions 43 are joined to the core wrap sheet 41 via a joining means such as an adhesive, whereby a predetermined arrangement is maintained.

In the absorber 4D shown in FIG. 9, a plurality (3) extending in the lateral direction Y from the vertical central region M to the rear region R in the central portion in the lateral direction Y (inside the rings of the annular recessed portions 7 and 8 described later). The groove-shaped recesses 42 are intermittently arranged in the vertical direction X. The small absorbing portion 43 is located between the two groove-shaped recesses 42 adjacent to each other in the vertical direction X. Each of the plurality of groove-shaped recesses 42 has a shape that is convexly curved toward one end on the rear region R side in the vertical direction X, and the top of the convex is located at the center of the lateral direction Y. .. In the absorber 4D, the groove-shaped recess 42 may have an opening in the non-skin facing surface 46 (see FIG. 5), or may have an opening in the skin facing surface 45 (see FIG. 6). Both the skin-facing surface 45 and the non-skin-facing surface 46 may have openings (see FIG. 7), or the absorbent core 40 may penetrate in the thickness direction (see FIG. 8).

In the absorber 4E shown in FIG. 10, a plurality of (two) groove-shaped recesses 42 extending in the vertical direction X are intermittently arranged in the lateral direction Y, and each groove-shaped recess 42 is in the lateral direction Y of the absorbent core 40. The central part is vertically crossed in the vertical direction X. The small absorbing portion 43 is located between the two groove-shaped recesses 42 adjacent to each other in the lateral direction Y. Each of the plurality of groove-shaped recesses 42 has a continuous linear shape extending in the vertical direction X in a plan view. In the absorber 4E, the groove-shaped recess 42 may have an opening in the non-skin facing surface 46 (see FIG. 5), or may have an opening in the skin facing surface 45 (see FIG. 6). Both the skin-facing surface 45 and the non-skin-facing surface 46 may have openings (see FIG. 7), or the absorbent core 40 may penetrate in the thickness direction (see FIG. 8).

The absorbent core 40 in the absorber 4 (4A to 4E) described above, that is, the absorbent core 40 having the groove-shaped recess 42, is a known product fiber as in the method for producing an absorbent core of this type of absorbent article. It can be manufactured using the device. The fiber stacking device typically includes a rotating drum having a recess for accumulation on the outer peripheral surface, and while rotating the rotating drum, supplies the core forming material to the outer peripheral surface in a scattered state to accumulate the core forming material. The fibers are stacked in the accumulation recess by suction from the bottom surface of the accumulation recess, and the fiber product in the accumulation recess is separated from the accumulation recess by suction from the suction means arranged so as to face the accumulation recess. , A device that transfers onto a suction means. In the fiber stacking device having such a configuration, a non-or breathable member is arranged on a part of the breathable bottom surface of the accumulation recess, and a part of the bottom surface is made into a non-breathable part. When the core-forming material is piled up, it becomes difficult for the core-forming material to be piled up in the non-breathable portion, and the amount of the core-forming material in the non-breathable portion is larger than that of other parts on the bottom surface. Will decrease. Therefore, by manufacturing an absorbent core according to a conventional method using a fiber stacking device equipped with a rotating drum in which a part of the bottom surface of the accumulation recess is a non-or breathable portion, the non-or difficult The portion corresponding to the breathable portion is the groove-shaped recess 42, and the portion corresponding to the other portion on the bottom surface is the small absorption portion 43, so that the absorbent core 40 having the groove-shaped recess 42 can be obtained.

As described above, the absorbent core 40 formed by partially differentizing the suction force when sucking the core forming material into the accumulating recess has a specific difference in the amount of fibers accumulated in the core forming material. The existing portion of the groove-shaped recess 42 (the portion of the absorbent core 40 that overlaps the groove-shaped recess 42 in a plan view) has a relatively small mass (basis weight) per unit area of the core forming material (basis weight). The non-existent portion of the groove-shaped recess 42 (including zero), that is, the small absorbing portion 43 has a relatively large basis weight.

From the viewpoint of ensuring that the absorption core 40 has the groove-shaped recess 42 and the small absorption portion 43 to exert the action and effect more reliably, the dimensions and the like of each portion of the absorption core 40 shall be set as follows. Is preferable.
The length (width) in the direction orthogonal to the length direction of the groove-shaped recess 42, for example, in the case of the vertical recess 42X extending in the vertical direction X, the length (width) in the horizontal direction Y is preferably 1.0 mm or more. , More preferably 3.0 mm or more, and preferably 10.0 mm or less, more preferably 5.0 mm or less.
The small absorption portion 43 as shown in FIG. 4, that is, the "small absorption portion 43 divided by the groove-shaped recesses 42X and 42Y that intersect (orthogonally) each other", in other words, the "small absorption portion 43 surrounded by the groove-shaped recess 42". The area of "" is preferably 25 mm ² or more, more preferably 50 mm ² or more, and preferably 1000 mm ² or less, more preferably 500 mm ² or less.
The number of small absorbing portions 43 per unit area of 2500 mm ² is preferably 2 or more, more preferably 5 or more, and preferably 100 or less, more preferably 50 or less.
The basis weight of the small absorption portion 43 (the portion of the absorbent core 40 that overlaps the small absorption portion 43 in a plan view) is based on the basis weight of the surrounding "part that overlaps the groove-shaped recess 42 in the absorbent core 40 in a plan view". It is preferably 150 g / m ² or more, more preferably 200 g / m ² or more, and preferably 800 g / m ² or less, more preferably 750 g / m ² or less, on the premise that it is also large.
The mass (basis weight) per unit area of the continuous layer 44 is preferably 30 g / m ² or more, more preferably 50 g / m ² or more, and preferably 160 g / m ² or less, more preferably 150 g / m ² or less. Is.

The absorbent core 40 is mainly composed of the core-forming material, and is typically composed of only the core-forming material. The core-forming material includes at least a water-absorbent fiber 12F and a fiber mass 11 containing the fiber 11F. The constituent fibers 11F of the fiber mass 11 are typically synthetic fibers. The absorbent core 40 shown in FIG. 2 further contains a particulate water-absorbent polymer 13 in addition to the fiber mass 11 and the water-absorbent fiber 12F.

One of the main characteristic portions of the napkin 1 is that the absorbent core 40, which is the main component of the absorber 4, contains the fiber mass 11. In the following, the absorbent core 40 will be mainly described, but the absorbent core 40 can be said to be substantially the absorber 4 itself, and the following description of the absorbent core 40 will be described unless otherwise specified. Appropriately applied as a description of the absorber 4. The absorber according to the present invention includes a form composed of only an absorbent core without containing a core wrap sheet, and in such a form of the absorber, the absorber and the absorbent core have the same meaning. ..

As used herein, the term "fiber mass" refers to a fiber aggregate in which a plurality of fibers are grouped together and integrated. The fiber mass used in the present invention may be a fixed-sized fiber aggregate such as a sheet piece obtained by cutting a synthetic fiber sheet having a certain size with a cutter or the like, regardless of the manufacturing method thereof. An amorphous fiber aggregate produced by crushing, or peeling or tearing off, a non-woven fabric mainly composed of synthetic fibers into fine pieces, such as the non-woven fabric piece described in Patent Document 2, may be used. In the present invention, the absorber (absorbable core) may be in the form of i) containing only a fixed fiber aggregate as a fiber mass, ii) a form containing only an amorphous fiber aggregate as a fiber mass, or iii. ) The fiber mass may be a mixture of a fixed fiber aggregate and an atypical fiber aggregate, but the form i) is preferably used. Since the constituent fibers of the amorphous fiber aggregate are randomly oriented, the surface is rough due to the fibers protruding from various parts of the surface, and the fiber aggregates are spread over the entire surface thereof. Entanglement may result in limited freedom of movement for each fiber assembly and reduced flexibility. The fiber mass 11 of the present embodiment is a fixed-form fiber aggregate as described later.

As described above, the fiber lump 11 is a fiber aggregate in which a plurality of fibers 11F are integrated in a lump shape, and a plurality of fibers 11F are present in the absorbent core 40 while maintaining its morphology. The fiber mass 11 mainly contributes to the improvement of the flexibility, cushioning property, compression recovery property, and shape retention property of the absorbent core 40 due to the morphology of the fiber aggregate.

A plurality of water-absorbent fibers 12F are present in the absorbent core 40, and although the plurality of water-absorbent fibers 12F can be entangled with each other, they are not integrated like the constituent fibers 11F of the fiber mass 11, and are individually independent. It is preferably present in. The water-absorbent fiber 12F mainly contributes to the improvement of the liquid absorbency of the absorbent core 40, and also contributes to the improvement of the shape retention of the absorbent core 40.

As the water-absorbent fiber 12F, a water-absorbent fiber conventionally used as a material for forming an absorber of this kind of absorbent article can be used. Examples of the water-absorbent fiber include wood pulp such as coniferous pulp and broadleaf pulp, natural fiber such as non-wood pulp such as cotton pulp and hemp pulp; modified pulp such as cationized pulp and marcelled pulp; cupra, rayon and the like. Regenerated fibers and the like can be mentioned, and one of these can be used alone or in combination of two or more. Considering that the main role of the water-absorbent fiber 12F is to improve the liquid absorbency of the absorber 4, the water-absorbent fiber 12F is preferably a natural fiber or a regenerated fiber (cellulosic fiber).

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

In the absorbent core 40, not only the plurality of fiber lumps 11 and the water-absorbent fibers 12F are simply mixed, but also the fiber lumps 11 or the fiber lumps 11 and the water-absorbent fibers 12F are entangled with each other. As will be described later, in the napkin 1, where the recessed portions 7 and 8 are formed on the skin-facing surface and the non-skin-facing surface of the absorber 4 (see FIG. 2 and the like), the following fiber lumps 11 and the like are formed. Unless otherwise specified, the description of "entanglement" in the above applies to the portion of the absorbent core 40 in which the recessed portions 7 and 8 are not formed (low density portion 9). In the forming portion of the recessed portions 7 and 8 in the absorbent core 40, the fiber lumps 11 and the like may be entangled with each other, but depending on the forming method of the recessed portions 7 and 8, the fiber lumps 11 and the like are entangled with each other. It may not be.

In the absorbent core 40, a plurality of fiber masses 11 are entangled with the constituent fibers (fibers 11F and 12F) in the absorbent core 40 to form one fiber mass continuous body. Further, a plurality of fiber lumps 11 may be entangled with each other, and the fiber lumps 11 and the water-absorbent fiber 12F may be entangled and bonded to each other. Further, usually, a plurality of water-absorbent 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 the water-absorbent fiber 12F. In the absorbent core 40, it is possible that all of the plurality of fiber masses 11 contained therein are entangled with each other to form one fiber mass continuum, and the plurality of fiber mass continuums are not mutually exclusive. It may be mixed in a combined state.

In the absorbent core 40, in addition to containing the fiber mass 11 that can enhance the flexibility of the absorbent core 40, the fiber masses 11 or the fiber masses 11 and the water-absorbent fiber 12F are also entangled with each other. Since they are combined, the absorbent core 40 is more excellent in responsiveness to external force, and is excellent in flexibility, cushioning property, and compression recovery property. The absorbent core 40 can be flexibly deformed by an external force (for example, the body pressure of the wearer of the napkin 1) received from various directions when the napkin 1 is worn, and the napkin 1 can be brought into close contact with the wearer's body with good fit. .. Such excellent deformation-recovery properties of the absorbent core 40 can be exhibited not only when the absorbent core 40 is compressed, but also when it is twisted. That is, since the absorbent core 40 incorporated in the napkin 1 is arranged so as to be sandwiched between the wearer's thighs when the napkin 1 is worn, both thighs during the wearer's walking motion. Depending on the movement of the part, it may be twisted around a virtual rotation axis extending in the vertical direction X, but even in such a case, since the absorbent core 40 has high deformation-recovery characteristics, both thighs It easily deforms and recovers against an external force that promotes twisting from the napkin, and therefore does not easily twist, and can give the napkin 1 a high fit to the wearer's body.

In the absorbent core 40, the fiber lumps 11 are entangled with each other or the fiber lumps 11 and the water-absorbent fiber 12F are entangled with each other. The "entanglement" between the fiber lumps 11 and the like includes the following forms A and B. Will be done.
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 term "state in which an external force is applied to the absorbent core 40" as used herein means, for example, that the absorbent core 40 is worn while wearing an absorbent article (napkin 1 in the present embodiment) to which the absorbent core 40 is applied. It is in a state where a deforming force is applied.

As described above, in the absorbent core 40, as in the form A, the fiber mass 11 is bonded to the other fiber mass 11 or the water-absorbent 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 another fiber mass 11 or water-absorbent fiber 12F. The entangled binding of such fibers is one of the important points for more effectively expressing the effects of the above-mentioned absorbable core 40. In particular, it is preferable that the absorbent core 40 has the "entanglement" of Form A from the viewpoint of shape retention. Since the entangled bonds of the fibers have no adhesive components or fusion and are made only by the entanglement of the fibers, the individual elements (fiber mass 11, water absorption) that are entangled are compared with the bonds by the entanglement of the fibers. The degree of freedom of movement of the sex fibers 12F) is high, so that the individual elements can move within a range that can maintain the unity as an aggregate composed of them. 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 water-absorbent fiber 12F are relatively loosely bonded to each other. It has possible loose shape retention, and has both shape retention, cushioning, compression recovery, etc. at a high level. The napkin 1 provided with such a high-quality absorbent core 40 fits well to the wearer's body and has an excellent wearing feeling.

Not all of the binding modes via the fiber mass 11 in the absorbent core 40 need to be "entangled", and a part of the absorbent core 40 includes other binding modes other than entanglement, such as bonding with an adhesive. May be. However, "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 a known leak-proof groove was excluded from the absorbent core 40. In the remaining portion, that is, the raw absorbent core 40 itself, it is desirable that the fiber lumps 11 are bonded to each other or the fiber lumps 11 and the water-absorbent fiber 12F are bonded only by "entanglement of fibers".

Since the napkin 1 has the above-mentioned configuration, that is, 1) a groove-shaped recess 42 is formed in the absorbent core 40, and 2) the absorbent core 40 is a fiber mass 11 containing the synthetic fiber 11F. By containing the water-absorbent fiber 12F, it does not easily get twisted when worn, has a good wearing feeling, and has excellent liquid absorption.

More specifically, as described above, the absorbent core 40 has a groove-shaped recess 42 that can act as a bending guide portion (flexible shaft), so that the body shape of the wearer when the napkin 1 is worn is formed. The napkin 1 is excellent in fit and wearing feeling because it is easily deformed along the line. Further, the groove-shaped recess 42 functions as a stock layer that temporarily holds body fluid such as menstrual blood excreted by the wearer of the napkin 1, and diffuses in the surface direction of the absorbent core 40, so that the napkin 1 is a liquid. It also has excellent absorbency. The absorbent core 40, which has excellent characteristics due to the groove-shaped recess 42, has a fiber mass that can contribute to the improvement of the flexibility, cushioning property, compression recovery property, and shape retention property of the absorbent core 40. Since 11 is contained, the action and effect of the groove-shaped recess 42, particularly the wearing feeling and the fit, are further improved, and it is difficult to twist. Further, since the constituent fibers 11F of the fiber mass 11 typically contain hydrophobic synthetic fibers, the napkin 1 absorbs body fluids and has excellent shape retention even after wetting. Therefore, the napkin 1 absorbs body fluids. Also, the action and effect of the fiber mass 11 can be exhibited.

Further, in the absorbent core 40, since the plurality of fiber lumps 11 or the fiber lumps 11 and the water-absorbent fiber 12F are entangled with each other, the absorbent core 40 is also excellent in shape retention in this respect and is in a dry state. Not to mention, it is hard to twist even after absorbing body fluids and becoming moist.

From the viewpoint of ensuring the action and effect of the napkin 1 described above, the fiber mass 11 and the water-absorbent fiber 12F are present in the continuous layer 44 (see FIGS. 5 to 7) of the absorbent core 40. Is preferable.

Further, in addition to the presence of the fiber mass 11 and the water-absorbent fiber 12F in the continuous layer 44, the continuous layer 44 is unevenly distributed on the skin-facing surface 45 side of the absorbent core 40 as shown in FIG. As shown in FIG. 6, if the absorbent core 40 is unevenly distributed on the non-skin facing surface 46 side, the action and effect of the napkin 1 described above can be more reliably exerted, which is preferable. In this case, the side opposite to the continuous layer 44 side of the absorbent core 40 is the side where the opening of the groove-shaped recess 42 is located, and the amount of the core forming material such as the fiber mass 11 is smaller than that of the continuous layer 44 side. That is, the continuous layer 44 side of the absorbent core 40 (the skin facing surface 45 side in the absorber 4 shown in FIG. 5) is more than the opposite side (the non-skin facing surface 46 side in the absorber 4 shown in FIG. 5). There can be many fiber lumps 11.

Further, in this way, when the continuous layer 44 containing the fiber mass 11 and the water-absorbent fiber 12F is unevenly distributed on the skin facing surface 45 side or the non-skin facing surface 46 side of the absorbent core 40, the depth of the groove-shaped recess 42 D (see FIG. 5) is preferably 40% or more, more preferably 50% or more, and preferably 98% or less, more preferably 80% with respect to the thickness T (see FIG. 5) of the absorbent core 40. It is as follows.

The thickness T of the absorbent core 40, that is, the thickness of the non-existent portion (small absorbing portion 43) of the groove-shaped recess 42 is preferably 2.0 mm or more, more preferably 3.0 mm or more, and preferably 10.0 mm or less. , More preferably 8.0 mm or less.
The thickness of each part of the absorbent core 40 is measured by the following method. The thickness of the entire absorbent core 40 (absorbent body 4), the thickness of the napkin 1, and the like can also be measured according to the following method.

<Thickness measurement method>
The absorbent core (absorber) is placed on a horizontal surface so as not to be wrinkled or bent, and the measurement target site (for example, the skin-facing surface side or the non-skin facing surface side of the absorbent core) is separated from the absorbent core. Cut out and use as a measurement sample. Then, the thickness of the measurement sample under a load of 5 cN / cm ² is measured. Specifically, for example, a thickness meter PEACOCK DIAL UPRIGHT GAUGES R5-C (manufactured by OZAKI MFG.CO.LTD.) Is used for measuring the thickness. At this time, a planar circular or square plate (acrylic plate with a thickness of about 5 mm) whose size is adjusted so that the load is 5 cN / cm ² is placed between the tip of the thickness gauge and the measurement sample. Then measure the thickness. In the thickness measurement, any 10 points in the measurement sample are measured, and the average value of the thicknesses of those 10 points is calculated and used as the thickness of the measurement sample.

In the absorbent core 40, the fiber lumps 11 may be distributed in any manner, for example, they may be uniformly distributed throughout the absorbent core 40, or may be unevenly distributed in a part of the absorbent core 40. Good. Further, in the latter case, the fiber mass 11 may be unevenly distributed in a part of the absorbent core 40 in the plane direction (for example, any one or two of the front region F, the longitudinal center region M, and the rear region R). , The absorbent core 40 may be unevenly distributed on a part of the thickness direction (for example, the skin facing surface 45 side or the non-skin facing surface 46 side). The "skin facing surface 45 side" referred to here refers to the skin facing surface when the absorbent core 40 in the region (for example, front region F, vertical center region M or rear region R) is bisected in the thickness direction. The portion closer to the surface 45, and the “non-skin facing surface 46 side” is the portion closer to the non-skin facing surface 46 in such a case.

At least in the vertical central region M, it is preferable that the non-skin facing surface 46 side of the absorbent core 40 has a larger mass (basis weight) per unit area of the fiber mass 11 than the skin facing surface 45 side. With such a configuration, the action effect mainly by the fiber lump 11 such as the cushioning property and the effect of improving the resistance to twisting is enhanced. Further, in this case, the mass (basis weight) per unit area of the water-absorbent fiber 12F can be larger on the skin-facing surface 45 side of the absorbent core 40 in the vertical center region M than on the non-skin facing surface 46 side. , A water-absorbent fiber 12F having excellent water absorption is compared on the skin-facing surface 45 side of the water-absorbent core 40 in the vertical center region M, which is the part of the absorbable core 40 that first receives the body fluid excreted by the wearer of the napkin 1. When it is contained in a large amount, the liquid drawing force (capillary force) of this portion is improved, and the liquid absorption of the absorbent core 40 is improved. Therefore, in the absorbent core 40 in the vertical center region M, the magnitude relationship of "the basis weight of the fiber mass 11 on the non-skin facing surface 46 side> the basis weight of the fiber mass 11 on the skin facing surface 45 side" is established. It is possible to further improve the possibility that the napkin 1 is less likely to be twisted when worn, has a good wearing feeling, and is excellent in liquid absorption. It is more preferable that the magnitude relationship is established not only in the vertical central region M but also in the entire absorbent core 40.

In the front region F and the rear region R, similarly to the vertical center region M, in the absorbent core 40, “the basis weight of the fiber mass 11 on the non-skin facing surface 46 side> the basis weight of the fiber mass 11 on the skin facing surface 45 side”. It is preferable that the magnitude relationship of "quantity" is established.

The ratio of the basis weight of the fiber mass 11 on the non-skin facing surface 46 side of the absorbent core 40 to that on the skin facing surface 45 side is preferably 1.1 or more, more preferably 10 or more as the former / the latter.
The basis weight of the fiber mass 11 on the non-skin facing surface 46 side of the absorbent core 40 is preferably 32 g / m ² or more, more preferably 80 g / m ² on the assumption that it is larger than that on the skin facing surface 45 side. The above, preferably 640 g / m ² or less, and more preferably 480 g / m ² or less.
Assuming that the basis weight of the fiber mass 11 on the skin-facing surface 45 side of the absorbent core 40 is smaller than that on the non-skin-facing surface 46 side, it is preferably 320 g / m ² or less, more preferably 240 g / m ^2. It is less than or equal to 0 g / m ² .

In the absorbent core 40, it is preferable that the vertical central region M has a larger mass (basis weight) per unit area of the fiber mass 11 than the front region F and the rear region R. Since the absorbent core 40 in the vertical central region M is usually sandwiched between the wearer's thighs when the napkin 1 is worn, the movement of both thighs during the wearer's walking motion causes the vertical X. It is easy to be twisted around a virtual rotation axis extending to, and an external force is likely to act stronger than the front area F and the rear area R, and twisting is likely to occur. Here, in the absorbent core 40, the above-mentioned magnitude relationship "basis weight of the fiber mass 11 in the vertical central region M> the basis weight of the fiber mass 11 in each of the front region F and the rear region R" is established, and relatively twisting occurs. The absorbent core 40 in the vertical center region M, which is easy to use, contains more fiber lumps 11 that can contribute to the improvement of cushioning property, compression recovery property, shape retention property, etc. than the front region F and the rear region R. , The inconvenience that the absorber 4 is twisted when the napkin 1 is worn can be effectively prevented, and the wearing feeling can be further improved.

The ratio of the basis weight of the fiber mass 11 of the absorbent core 40 in the vertical central region M to that of each of the front region F and the rear region R is preferably 1.1 or more, more preferably 10 or more as the former / the latter. ..
Assuming that the basis weight of the fiber mass 11 of the absorbent core 40 in the vertical central region M is larger than that of each of the front region F and the rear region R, it is preferably 32 g / m ² or more, more preferably 80 g / m. ^{It is 2} or more, preferably 640 g / m ² or less, and more preferably 480 g / m ² or less.
The basis weight of the front region F and rear area R each fiber agglomerations 11 assuming smaller than that of the longitudinal central region M, preferably 320 g / ^{m 2} or less, more preferably 240 g / ^{m 2} or less, It may be 0 g / m ² .

The effect of establishing the above-mentioned magnitude relationship "basis weight of fiber mass 11 in vertical center region M> basis weight of fiber mass 11 in front region F and rear region R" is made more reliable. From the viewpoint, the absorbent core 40 preferably contains 90% by mass or more of all the fiber lumps 11 contained in the absorbent core 40 in the vertical central region M, and more preferably 95% by mass or more is present. Preferably, 100% by mass, that is, the entire fiber mass 11 contained in the absorbent core 40 may be present in the longitudinal center region M.

The uneven distribution of the fiber lumps 11 in the absorbent core 40 described above uses the total mass content of the fiber lumps 11 and the water-absorbent fibers 12F used as the core forming material of the absorbent core 40 together with the “fiber lumps 11 and water absorption”. It can also be defined as "the ratio of the content mass of the fiber mass 11 to the total content mass of the sex fiber 12F" (hereinafter, also referred to as "fiber mass occupancy rate").
That is, in relation to the magnitude relationship of "the basis weight of the fiber mass 11 on the non-skin facing surface 46 side> the basis weight of the fiber mass 11 on the skin facing surface 45 side", "the fiber mass on the non-skin facing surface 46 side". It is preferable that the magnitude relationship of "occupancy rate> fiber mass occupancy rate on the skin facing surface 45 side" is established.
Further, in relation to the magnitude relationship of "the basis weight of the fiber mass 11 in the vertical central region M> the basis weight of each fiber mass 11 in the front region F and the rear region R", "occupation of the fiber mass in the vertical central region M". It is preferable that the magnitude relationship of "rate> fiber mass occupancy of each of the front region F and the rear region R" is established.

The fiber mass occupancy rate is determined by measuring the content of each of the fiber mass 11 and the water-absorbent fiber 12F existing in the measurement target site by mass with respect to the predetermined measurement target portion of the absorbent core 40, and the fiber mass thus measured. The content mass of 11 is divided by the total value of the content mass of each of the water-absorbent fiber 12F and the fiber mass 11, and is expressed as a 100% ratio. That is, the fiber mass occupancy rate (mass%) = {content mass of fiber mass 11 / (content mass of water-absorbent fiber 12F + content mass of fiber mass 11)} × 100.

Assuming that the fiber mass occupancy on the non-skin facing surface 46 side of the absorbent core 40 is higher than that on the skin facing surface 45 side of the absorbent core 40, it is preferably 50% by mass or more, more preferably 90 mass. % Or more, that is, 100% by mass, that is, the non-skin facing surface 46 side does not have to contain the water-absorbent fiber 12F at all instead of containing the fiber mass 11.
Further, the fiber mass occupancy rate of the absorbent core 40 in the vertical center region M is preferably 50% by mass or more, more preferably 90% by mass or more, on the assumption that it is higher than that of each of the front region F and the rear region R. The 100% by mass, that is, the absorbent core 40 in the vertical center region M does not have to contain the water-absorbing fiber 12F at all instead of containing the fiber mass 11.

For example, in the absorbent core 40 in the vertical center region M, when the magnitude relationship of "fiber mass occupancy on the non-skin facing surface 46 side> fiber mass occupancy on the skin facing surface 45 side" is established, 1) skin. On each of the facing surface 45 side and the non-skin facing surface 46 side, the fiber mass occupancy rate may be constant without changing in the thickness direction, or 2) the fibers from the skin facing surface 45 side toward the non-skin facing surface 46 side. The mass occupancy may gradually increase. In the form of 2) above, in the thickness direction of the absorbent core 40, in the skin facing surface 45 of the absorbent core 40 and its vicinity, the fiber mass 11 is absent or is the lowest in the absorbent core 40 in the vertical center region M. It exists at the fiber mass occupancy, and in the non-skin facing surface 46 of the absorbent core 40 and its vicinity, the fiber mass 11 exists at the highest fiber mass occupancy in the absorbent core 40 in the longitudinal central region M. The front region F and the rear region R of the absorbent core 40 may also have the form of 1) or 2) above.

An advantage peculiar to the form of 1) is that it is easy to design the absorbent core to have independent functions on the skin-facing surface side and the non-skin-facing surface side. Further, as an advantage peculiar to the form of 2) above, since the mixing ratio of the water-absorbent fiber and the fiber mass gradually changes in the thickness direction of the absorber, the fiber mass is interposed even when an external force is applied to the absorbent core. The entangled state is easily maintained in the thickness direction, and the cushioning property of the absorbent core is easily maintained during use.

Further, the fiber mass occupancy rate may be gradually increased from each of the front region F and the rear region R of the absorbent core 40 toward the longitudinal central region M. For example, in each of the front region F and the rear region R, the fiber mass occupancy rate gradually increases from the outside to the inside in the vertical direction X, and the vertical center region M is in the form of 1) or 2) above. May be good.

In the napkin 1 of the present embodiment, as shown in FIGS. 1 and 2, the absorbent body 5 has a surface sheet 2, a core wrap sheet 41 (skin side core wrap sheet), and an absorber 4 (absorbent core 40). The surface recessed portion 7 integrally recessed on the non-skin facing surface side (back surface sheet 3 side) of the absorber 4 is formed at least in the vertical central region M. The surface recessed portion 7 does not penetrate the absorber 4 (absorbent core 40), has an opening on the skin-facing surface of the surface sheet 2, and has a bottom portion on the side opposite to the opening. The surface recessed portion 7 formed on the skin-facing surface of the napkin 1 has a function of inhibiting the movement of body fluid such as menstrual blood in the surface direction.

In the napkin 1, the surface recessed portion 7 extends in the vertical direction X in the vertical central region M, as shown in FIGS. 1 and 4. More specifically, the surface recessed portion 7 includes a pair of left and right surface longitudinal recessed portions 7X, 7X extending in the vertical direction X, and a pair of front and rear surface lateral recessed portions 7Y, 7Y extending in the horizontal direction Y. ing.

The pair of surface vertical recesses 7X and 7X extend over the entire length of the vertical central region M in the vertical direction X, and further extend to the front region F and the rear region R, respectively, forming a continuous linear shape as a whole. There is.
At least one of the pair of surface lateral recesses 7Y and 7Y is located in the front region F, and at least part of the other is located in the rear region R, both of which are in the vertical direction X in a plan view. It has a U-shaped or arc-shaped continuous linear shape that is convex outward, and the U-shaped or arc-shaped top is located at the center of the napkin 1A in the lateral direction Y.
The recessed portions 7X and 7Y constituting the surface recessed portion 7 are connected to each other at the ends in the length direction thereof, and the surface recessed portion 7 as a whole is a closed ring in a plan view, more specifically, a length. It has an elliptical shape. The region surrounded by the pair of surface vertical recessed portions 7X and 7X in the vertical central region M is located in the central portion of the vertical central region M and includes the excretion portion facing portion (excretion point).

In the napkin 1, as shown in FIG. 2, the core wrap sheet 41 (non-skin side core wrap sheet) and the absorbent core 40 face the skin of the absorbent core 40 at a position where they overlap the surface recessed portion 7 in a plan view. The back surface recessed portion 8 integrally recessed on the surface side (front surface sheet 2 side) is formed at least in the vertical center region M. The back surface recessed portion 8 does not penetrate the absorber 4 (absorbent core 40), has an opening on the non-skin facing surface of the absorber 4, and has a bottom portion on the side opposite to the opening. The front surface recessed portion 7 and the back surface recessed portion 8 share a bottom portion.

In the present embodiment, the back surface recessed portion 8 has substantially the same shape and dimensions as the surface recessed portion 7 in a plan view, and has the same closed annular shape as the front surface recessed portion 7. That is, the back surface recessed portion 8 extends in the vertical direction X, and extends in the horizontal direction Y with a pair of left and right back surface vertical recessed portions 8X, 8X that overlap the front surface vertical recessed portion 7X in a plan view and have the same plan view shape. , A pair of front and rear lateral concave recesses 8Y and 8Y (not shown) that overlap the front lateral concave recess 7Y in a plan view and have the same plan view shape, and each concave recess 8X and 8Y By connecting them at the end portions in the length direction, the back surface recessed portion 8 as a whole forms a closed annular shape (oblong shape) in a plan view.

The surface recessed portion 7 is formed by squeezing the absorbent main body 5 from the skin-facing surface side (surface sheet 2 side) more specifically than the napkin 1, and the "squeezed portion" is based on the forming method. Can be said. Further, the back surface recessed portion 8 is formed by applying a pressing process to the absorber 4 from the non-skin facing surface side (non-skin side core wrap sheet side), and is also referred to as a “squeezed portion”. it can. The dented portions 7 and 8 which are the squeezed portions have a higher density than the peripheral portions of the concave recessed portions 7 and 8 in the absorber 4. That is, the absorbent main body 5 has a high-density portion corresponding to the recessed portions 7 and 8 and a low-density portion 9 in which both recessed portions 7 and 8 are not formed, whereby a density difference occurs in the surface direction. ing.

The pressing process for forming the two recessed portions 7 and 8 involves melting the core-forming material contained in the absorber 4 (absorbent core 40), particularly melting the thermoplastic fiber preferably used as a constituent fiber of the fiber mass 11. The accompanying method may be used, or a method that does not involve melting of the core forming material may be used. Specific examples of the pressing process involving melting of the core forming material include known embossing processes such as heat embossing and ultrasonic embossing. At the bottom of the surface recessed portion 7 formed by the pressing process accompanied by melting of the core forming material, that is, the portion overlapping the surface recessed portion 7 which is a space portion in a plan view, the surface sheet 2 and the core wrap sheet 41 (skin side core wrap) The sheet) and the absorbent core 40 can be heat fused and integrated. Further, in the bottom portion of the back surface recessed portion 8 formed by the pressing process accompanied by melting of the core forming material, that is, the portion overlapping the back surface recessed portion 8 which is a space portion in a plan view, the core wrap sheet 41 (non-skin side core wrap sheet) ) And the absorbent core 40 can be heat fused and integrated. As described above, since the back surface recessed portion 8 and the front surface recessed portion 7 share the bottom portion, the front surface sheet 2 and the skin side are sequentially formed on the bottom portion common to both the back surface recessed portions 7 and 8 from the surface recessed portion 7 side. The core wrap sheet, the absorbent core 40 and the non-skin side core wrap sheet may exist in a state of being heat-sealed and integrated with each other.

The width of the surface recessed portion 7 (the length in the direction orthogonal to the length direction of the recessed portion) is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.5 mm or more, and preferably 10 mm or less. It is preferably 5 mm or less. The width of the back surface recessed portion 8 can be set to the same range.

As shown in FIGS. 1, 2 and 4, more specifically, the absorbent body 5 is a portion in which neither the front surface recess 7 nor the back surface recess 8 is formed, and the recess 7 is formed. , 8 There is a low density portion 9 having a lower density than that of 8. In the present embodiment, as described above, the recessed portions 7 and 8 have substantially the same shape and dimensions in a plan view, respectively, and have a closed annular shape (oblong shape). It exists both inside and outside the closed ring of the recesses 7 and 8. At least the peripheral portion of the absorbent body 5 and the central portion of the vertical central region M (the portion facing the excretion portion and its vicinity) are the low density portions 9.

It should be noted that the low density portion 9 is sandwiched between a pair of front surface vertical recessed portions 7X, 7X (back surface vertical concave recessed portions 8X, 8X) extending in the vertical direction X through both side portions in the horizontal direction Y of the vertical central region M. A squeezed portion formed by squeezing such as embossing may be partially present in the squeezed region (the central portion in the horizontal direction Y of the vertical central region M). In that case, the area of all the squeezed portions existing in the low density portion 9 occupying the total area of the low density portion 9 (specifically, for example, the region sandwiched between the pair of surface longitudinal recessed portions 7X, 7X). The total ratio is preferably 5% or less, more preferably 3% or less. In the napkin 1 of the present embodiment, the squeezed portion does not exist in the low density portion 9 sandwiched between the pair of surface longitudinal recessed portions 7X and 7X.

Since the absorbent core 40 contains the fiber mass 11, the properties such as shape retention and cushioning are improved as compared with the normal absorbent core 40 not containing the fiber mass 11, and the thickness is further increased. Having a squeezed and densified recess 7 further enhances these properties, for example, a strong lateral Y compressive force applied by both thighs of the wearer of the napkin 1. It does not easily lose its shape even when it receives an external force such as, it deforms quickly in response to an external force, and can be quickly restored if the external force is released.

Further, in the napkin 1, there is a density difference in the plane direction due to the coexistence of the recessed portions 7 and 8 having a relatively high density and the low density portion 9 having a relatively low density in the plane direction. The difference in density makes it easier for body fluids to diffuse in the plane direction. That is, the napkin 1 can rapidly diffuse the body fluid excreted by the wearer in the plane direction, and therefore, effectively utilizes the absorption performance inherently possessed by the absorbent core 40 to exhibit high liquid leakage resistance. Can be done.

In particular, as shown in FIGS. 1 and 4, the surface recessed portion 7 of the napkin 1 exists not only in the vertical central region M but also in the front region F and the rear region R, so that the shape retention of the entire napkin 1 is maintained. And the liquid diffusivity in the surface direction is enhanced.

Further, in the low density portion 9, a space portion formed between the plurality of fiber lumps 11 is formed due to the existence of the plurality of fiber lumps 11 in a state in which the original outer shape thereof is substantially maintained. There are a large number of them, and many of these spatial portions contribute to the development of the excellent cushioning property of the low-density portion 9, and can also function as a temporary stock portion of body fluid. Since the napkin 1 has a low-density portion 9 that can function as a temporary stock portion of such body fluid in the vertical central region M where the excreted body fluid tends to concentrate, it has excellent liquid absorption ability. It is possible to exhibit high liquid leakage proofing property, and due to its high liquid drawing property, it is possible to reduce the liquid residue on the skin-facing surface of the surface sheet 2 and suppress an unpleasant wet feeling and sticky feeling.

Further, since the low density portion 9 having excellent cushioning property is present in the vertical central region M where the excretion portion facing portion exists, the vertical central region M is not only in a dry state before absorption of body fluid but also after absorption of body fluid. Even in the wet state, it is flexible and rich in cushioning due to the action of the low density portion 9.

As described above, in the vertical central region M, when the mass (basis weight) per unit area of the fiber mass 11 is different between the skin facing surface 45 side and the non-skin facing surface 46 side of the absorbent core 40, the surface is recessed. It is preferable that the portion 7 overlaps with the fiber mass 11 in a plan view, and in the vertical central region M, the basis weight of the fiber mass 11 extends to a region different from the skin facing surface 45 side of the absorbent core 40. More specifically, for example, in the absorbent core 40 in the vertical central region M, the size of the above-mentioned "basis weight of the fiber mass 11 on the non-skin facing surface 46 side> basis weight of the fiber mass 11 on the skin facing surface 45 side". When the relationship is established, the surface recessed portion 7 (surface longitudinal recessed portion 7X, surface lateral recessed portion 7Y) overlaps the fiber mass 11 in a plan view, and in the vertical center region M, extends to the non-skin facing surface 46 side. It is preferable that it reaches. As described above, the skin-facing surface 45 side of the absorbent core 40 in the vertical central region M is the skin-facing surface 45 when the absorbent core 40 in the vertical central region M is bisected in the thickness direction. It is a portion closer to the non-skin facing surface 46, and the non-skin facing surface 46 side is a portion closer to the non-skin facing surface 46 in such a case. With such a configuration, the action effect (effect of improving shape retention, effect of improving liquid diffusivity in the surface direction, etc.) by the above-mentioned recessed portions 7 and 8 and the low density portion 9 is further improved, and absorption during wearing is further improved. The twist of the body 4 can be prevented more reliably. It should be noted that such a configuration can also be applied when the fiber mass occupancy rate differs between the skin-facing surface 45 side and the non-skin-facing surface 46 side of the absorbent core 40. That is, for example, in the absorbent core 40 in the vertical center region M, when the magnitude relationship of "fiber mass occupancy on the non-skin facing surface 46 side> fiber mass occupancy on the skin facing surface 45 side" is established, the surface surface. It is preferable that the recessed portion 7 (surface longitudinal recessed portion 7X, surface lateral concave recessed portion 7Y) overlaps the fiber mass 11 in a plan view, and extends to the non-skin facing surface 46 side in the vertical central region M.

Further, in the vertical central region M, the surface recesses 7 (more specifically, a pair of surface vertical recesses 7X, 7X) on both sides in the horizontal direction Y and the regions sandwiched between them (hereinafter, "inward in the horizontal direction"). The region ”is also referred to as“ region ”) of the fiber mass 11 as compared with the outer side of the surface concave portion 7 (the lateral inner region) in the lateral direction Y (hereinafter, also referred to as“ lateral outer region ”). It is preferable that the mass (basis weight) per unit area is large. In the napkin 1, as shown in FIGS. 1, 2 and 4, the lateral inward region is the low density portion 9. With such a configuration, it is possible to promote the liquid diffusivity in the front-rear direction in the vertical direction X while ensuring the liquid absorption rate at the surface concave portion 7 (surface vertical concave portion 7X) in the vertical central region M. Leakage can be effectively suppressed. The ratio of the basis weight of the fiber mass 11 to the lateral outer region and the lateral inner region is set as the former (lateral outer region) / latter (lateral inner region) on the premise of the former <the latter. It is preferably 0 or more, more preferably 0.1 or more, and preferably less than 1.0, more preferably 0.9 or less.

The surface recessed portion 7 (surface longitudinal recessed portion 7X), which is the boundary between the horizontal inner region and the lateral outer region in the vertical central region M, extends in the vertical direction X. The term "extended" as used herein includes not only the case where the surface recessed portion 7 extends continuously in the vertical direction X as shown in FIG. 1, but also a plurality of surface recessed portions 7 as shown in FIG. 11, for example. Is intermittently arranged in the vertical direction X, and a case is included in which the plurality of surface recessed portions 7 extend in the vertical direction X as a whole. In the latter case, the separation distance of the two surface recesses 7 closest to each other in the vertical direction X in the vertical direction X is preferably 30 mm or less, and more preferably 20 mm or less. The same applies to the plurality of back surface recessed portions 8 intermittently arranged in the vertical direction X.

From the viewpoint of ensuring that the effects caused by the recessed portions 7 and 8 and the low-density portion 9 are more reliably achieved, the dimensions and the like of each portion of the napkin 1 are preferably set as follows.
In the vertical central region M, the separation distance W1 (see FIG. 1) between the side edge of the absorber 4 (absorbent core 40) along the vertical direction X and the concave portions 7, 8 (vertical concave portions 7X, 8X) in the horizontal direction Y (see FIG. 1). ) Is preferably 5 mm or more, more preferably 10 mm or more, and preferably 25 mm or less, more preferably 20 mm or less. When the length (width) of the absorber 4 in the lateral direction Y is not constant, the separation distance W1 is a measured value at the portion where the width of the absorber 4 is the widest.
The length, that is, the width W2 (see FIG. 1) of the low density portion 9 of the low density portion 9 in the vertical central region M is preferably 20 mm or more, more preferably 25 mm or more, and preferably 70 mm or less, more preferably 65 mm or less. is there.

The ratio of the total area of the surface recessed portion 7 to the total area of the skin-facing surface of the absorber 4 (absorbent core 40) (recessed portion occupancy rate) is preferably 0.02% or more, more preferably 0.1. % Or more, preferably 15% or less, more preferably 10% or less. The ratio of the total area of the back surface recessed portion 8 to the total area of the non-skin facing surface of the absorber 4 (absorbent core 40) (recessed portion occupancy rate) may be the same as that of the surface recessed portion 7.
The depth of the surface recessed portion 7 (7X, 7Y) (the depth based on the non-recessed portion on the skin-facing surface of the surface sheet 2) is preferably 0.1 mm or more, more preferably 0.2 mm or more. Then, it is preferably 2.0 mm or less, more preferably 1.0 mm or less.
The depth of the back surface recessed portion 8 (8X, 8Y) (the depth based on the non-recessed portion on the non-skin facing surface of the absorber 4) is preferably 0.1 mm or more, more preferably 0.2 mm or more. , And preferably 2.0 mm or less, more preferably 1.0 mm or less.

In the napkin 1, the depths of the recesses 7 and 8 may be constant or partially different over the entire length in the length direction thereof. Further, the shape, arrangement, and the like of the linear recessed portions 7 and 8 are not limited to the illustrated form, and can be set in the same manner as those called leak-proof grooves in this type of absorbent article. The linear recesses 7 and 8 may be configured to include a straight line and / or a curved line in a plan view shape, and each line may be a continuous line, and a broken line (two types of portions having different depths are lines). The shape may be arranged alternately in the extending direction of the concave portions).

Further, in the absorbent article of the present invention, the patterns (planar view shape and arrangement) of the recessed portions 7 and 8 are not limited to those having a planar line-of-sight shape such as the recessed portions 7 and 8 shown in FIG. It may be a dot shape such as a circle, an ellipse, a rectangle, a triangle, a star, or a heart. In the absorber 4F shown in FIG. 11, circular surface recesses 7 in a plan view are formed in a scattered pattern in the vertical central region M, and more specifically, a plurality (three) surface recesses 7 are formed in the vertical direction X. The recessed rows are arranged intermittently in the vertical direction X, and the recessed rows are arranged in pairs at intervals in the horizontal direction Y. Although not shown, the back surface concave portion 8 is formed in the same pattern as the front surface concave portion 7 on the non-skin facing surface side of the absorber 4. The absorber 4F is configured in the same manner as the absorber 4 described above except for the patterns of the recessed portions 7 and 8, and the description of the absorber 4 is appropriately applied to the configurations not particularly described in the absorber 4F.

In the absorbent core 40, the content mass ratio of the fiber mass 11 and the water-absorbent fiber 12F is not particularly limited, and is appropriately adjusted according to the types of the constituent fibers (synthetic fibers) 11F and the water-absorbent fiber 12F of the fiber mass 11. Just do it. For example, when the constituent fibers 11F of the fiber mass 11 are thermoplastic fibers (non-water-absorbent synthetic fibers) and the water-absorbent fibers 12F are cellulose-based water-absorbent fibers, the predetermined effects of the present invention can be more reliably achieved. The content mass ratio of the fiber mass 11 and the water-absorbent fiber 12F is preferably 20/80 to 80/20, more preferably 40, as the former (fiber mass 11) / the latter (water-absorbent fiber 12F). It is / 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, based on the total mass of the absorbent core 40 in the dry state. , More preferably 60% by mass or less.
The content of the water-absorbent 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 with respect to the total mass of the absorbent core 40 in the dry state. Hereinafter, it is more preferably 60% by mass or less.
The content of the water-absorbent polymer 13 in the absorbent core 40 is preferably 1% by mass or more, more preferably 5% by mass or more, and preferably 80% by mass, based on the total mass of the absorbent core 40 in the dry state. Hereinafter, it is more preferably 50% by mass or less.
The "dry absorbable core" here means an absorbable core before absorbing body fluids.

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

As described above, the absorber 4 (absorbent core 40) can be manufactured according to a conventional method using a known fiber stacking device equipped with a rotating drum. As described above, the absorber 4 has a form in which the core forming material (fiber mass 11, water-absorbent fiber 12F, water-absorbent polymer 13) is uniformly distributed throughout the absorbent core 40, and fibers are partially distributed in the absorbent core 40. The lump 11 (water-absorbent fiber 12F) is unevenly distributed, and any form can be produced according to a conventional method using a known fiber stacking device. In particular, the latter form in which the fiber mass 11 (water-absorbent fiber 12F) is unevenly distributed in a part of the absorbent core 40 is a form in which the fiber mass 11 or the water-absorbent fiber 12F is used in a method for producing an absorber using a known fiber stacking device. It can be manufactured by appropriately adjusting the fiber stacking order on the rotating drum.

Hereinafter, the fiber mass 11 will be further described. FIG. 12 shows two typical outer shapes of the fiber mass 11. The fiber mass 11A shown in FIG. 12A has a rectangular parallelepiped shape rather than a square prism shape, and the fiber mass 11B shown in FIG. 12B 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 of FIG. 12A has six flat surfaces, and of the six surfaces, two opposing surfaces having the maximum area are 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 with each other, and more specifically, are orthogonal to each other.
The disk-shaped fiber mass 11B of FIG. 12B 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. 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.

Examples of the form of the fiber mass 11 include a sheet piece divided from a synthetic fiber sheet having a certain size. That is, the sheet piece-shaped fiber mass, which is a preferred embodiment of the fiber mass 11, is not configured to accumulate a plurality of fibers to form the sheet piece, but is a fiber having a size larger than that of the sheet piece. It is produced by cutting a sheet (see FIG. 13), and is a plurality of sheet piece-like fiber lumps having high morphological properties as compared with those produced by the above-mentioned conventional technique.

The fiber mass 11 which is a "standard fiber aggregate" defined by the two basic surfaces 111 and the skeleton surface 112 intersecting both basic surfaces 111 differs from the conventional technique in the manufacturing method. It can be realized by. As described above, as shown in FIG. 13, a preferable method for producing the fiber mass 11 is to use a raw material fiber sheet 10bs (a sheet having the same composition as the fiber mass 11 and a size larger than the fiber mass 11) as a raw material, a cutter or the like. It is cut into a fixed shape by using the cutting means of. The plurality of fiber lumps 11 thus produced have a more morphological shape and dimensions as compared with those produced by the above-mentioned prior art. FIG. 13 is a diagram illustrating a method of manufacturing the rectangular parallelepiped-shaped fiber mass 11A of FIG. 12A, and the dotted line in FIG. 13 indicates a cutting line. The absorbent core 40 is blended with a plurality of fiber lumps 11 having a uniform shape and size obtained by cutting the fiber sheet into a fixed shape in this way.

As shown in FIG. 13, the rectangular parallelepiped-shaped fiber mass 11A of FIG. 12A crosses (more specifically, orthogonally) the first direction D1 and the first direction D1 with the raw material fiber sheet 10bs 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 of the raw material fiber sheet 10bs, and the raw material fiber sheet 10bs is cut along the thickness direction Z orthogonal to the plane direction. In this way, the plurality of rectangular parallelepiped-shaped fiber lumps 11A obtained by cutting the raw material fiber sheet 10bs into a so-called sword-like pattern usually come into contact with a cutting means such as a cutter when the cut surface, that is, the raw material fiber sheet 10bs is cut. The surface is the skeleton surface 112, and 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 the front and back surfaces (planes orthogonal to the thickness direction Z) of the raw material fiber sheet 10bs, and as described above, is the surface having the largest area among the plurality of surfaces of the fiber mass 11A.

The above description of the fiber mass 11A basically applies to the disk-shaped fiber mass 11B of FIG. 12B. The only substantial difference from the fiber mass 11A is the cutting pattern of the raw material fiber sheet 10bs, and when the raw material fiber sheet 10bs is cut into a fixed shape to obtain the fiber mass 11B, it is matched to the plan view shape of the fiber mass 11B. Then, the raw material fiber sheet 10bs may be cut into a circular shape.

As described above, the above-mentioned patent document describes 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. In order to improve the uniform dispersibility of the fiber mass 11 in the absorbent core 40 as compared with the case of an amorphous fiber aggregate such as, the fiber aggregate such as the fiber mass 11 is blended into the absorbent core 40. The expected effects (improvement effect of absorber flexibility, cushioning property, compression recovery property, etc.) will be exhibited more stably. Further, in particular, in the case of the rectangular parallelepiped main body 110 as shown in FIG. 12A, since the outer surface thereof is composed of six surfaces of two basic surfaces 111 and four skeleton surfaces 112, the other fiber mass 11 or water absorption. It is possible to have a relatively large number of contact opportunities with the fiber 12F, the entanglement is enhanced, and the shape retention and the like can be improved.

As the raw material fiber sheet 10bs used here, a non-woven fabric containing synthetic fibers is preferable from the viewpoint of further enhancing the cushioning property, compression recovery property and shape retention of the absorbent core 40, and the non-woven fabric having a heat-sealed portion between the synthetic fibers is preferable. Is more preferable. Further, an air-through non-woven fabric in which synthetic fibers have heat-sealing portions and a plurality of heat-sealing portions are three-dimensionally dispersed is particularly preferable.

The outer shape of the main body 110 is not limited to that shown in FIG. 12, and the basic surface 111 and the skeleton surface 112 are both flat surfaces that are not curved as in the surfaces 111 and 112 of FIG. 12 (a). It may be a curved surface as in the skeleton surface 112 of FIG. 12 (b). Further, the basic surface 111 and the skeleton surface 112 may have the same shape and the same dimensions, and specifically, for example, the outer shape of the main body 110 may be a cube shape.

As described above, the two types of surfaces (basic surface 111 and skeleton surface 112) of the fiber mass 11 (11A, 11B) are formed by cutting 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) to be formed 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. The skeleton surface 112, which is a cut surface, has a larger number of fiber ends per unit area than the basic surface 111, which is a non-cut surface, due to the difference in whether or not the cut surface is used. Has. The "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 portion is also present on the basic surface 111, which is a non-cut surface, but the skeleton surface 112 is formed by cutting the raw material fiber sheet 10bs because it is a cut surface formed by cutting. A large number of fiber ends consisting of cut ends of the constituent fibers 11F are present throughout the skeleton surface 112, that is, the number of fiber ends per unit area is larger than that of the basic surface 111. ..

The fiber ends existing on each surface (basic surface 111, skeleton surface 112) of the fiber mass 11 are formed between the fiber mass 11 and another fiber mass 11 included in the absorbent core 40 or the water-absorbent fiber 12F. It is useful for forming confounding. Further, in general, the larger the number of fiber ends per unit area, the more the entanglement can be improved, which can lead to the improvement of various characteristics such as the shape retention of the absorbent core 40. The number of fiber ends per unit area on each surface of the fiber mass 11 is not uniform, and a magnitude relationship of "skeleton surface 112> basic surface 111" is established with respect to the number of fiber ends per unit area. Therefore, the entanglement with other fibers (other fiber mass 11, water-absorbent fiber 12F) via the fiber mass 11 differs depending on the surface of the fiber mass 11, and the skeleton surface 112 is compared with the basic surface 111. Highly confounding. 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 bonding force with other fibers between 112 and 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 tends to increase, but the softness tends to decrease. ..

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, water-absorbent fibers 12F) around the absorbent core 40. As a result, 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.

On the other hand, the above-mentioned non-woven fabric piece described in the patent document is manufactured by cutting the raw material fiber sheet into an irregular shape by a cutting machine such as a mill cutter as described above, and therefore, therefore, the basic surface 111 and the skeleton surface. It is not a standard sheet piece-like fiber mass having a "face" like 112, and since the external force of the cutting process is applied to the entire fiber mass at the time of its manufacture, the fiber end portion of the constituent fiber is formed. It is randomly formed in the entire fiber mass, and it is difficult for the above-mentioned action and effect by the fiber end to be sufficiently exhibited.

From the viewpoint of ensuring the action and effect of the fiber ends described above, the number N1 per unit area of the fiber ends of the basic surface 111 (non-cut surface) and the fibers of the skeleton surface 112 (cut surface). The ratio of the end to the number N2 per unit area is preferably N1 / N2, preferably 0 or more, more preferably 0.05 or more, and preferably 0.90 or less, assuming N1 <N2. Is 0.60 or less. More specifically, N1 / N2 is preferably 0 or more and 0.90 or less, and more preferably 0.05 or more and 0.60 or more.
The number N1 per unit area of the fiber end of the basic surface 111 is preferably 0 pieces / mm ² or more, more preferably 3 pieces / mm ² or more, and preferably 8 pieces / mm ² or less, more preferably 6. Pieces / mm ² or less.
The number N2 per unit area of the fiber end of the skeleton surface 112 is preferably 5 pieces / mm ² or more, more preferably 8 pieces / mm ² or more, and preferably 50 pieces / mm ² or less, more preferably 40 pieces. Pieces / mm ² or less.
The number of fiber ends of the basic surface 111 and the skeleton surface 112 per unit area is measured by the following method.

<Measuring method of the number of fiber ends per unit area on each surface of the fiber mass>
A member (fiber mass) containing a fiber to be measured is attached to a sample table using a paper double-sided tape (Nichiban Co., Ltd. Nystack NW-15). The measurement piece is then platinum coated. An ion sputtering device E-1030 (trade name) manufactured by Hitachi Naka Seiki Co., Ltd. is used for coating, and the sputtering time is 120 seconds. The cut surface of the measurement piece is observed on the basic surface and the skeletal surface at a magnification of 100 times using a JCM-6000 type electron microscope manufactured by JEOL Ltd. In this observation screen with a magnification of 100 times, a rectangular area of 1.2 mm in length and 0.6 mm in width is set at an arbitrary position on the measurement target surface (basic surface or skeleton surface), and the area of the rectangular area is the said. After adjusting the observation angle and the like so as to occupy 90% or more of the area of the observation screen, the number of fiber ends included in the rectangular region is measured. However, on an observation screen with a magnification of 100 times, when the measurement target surface of the fiber mass is smaller than 1.2 mm × 0.6 mm and the ratio of the area of the rectangular region to the entire observation screen is less than 90%. After increasing the observation magnification to more than 100 times, the number of fiber ends contained in the rectangular region on the measurement target surface is measured in the same manner as described above. Here, the "fiber end" to be counted is the end in the length direction of the constituent fibers of the fiber mass, and the portion other than the end in the length direction of the constituent fibers from the measurement target surface (intermediate in the length direction). Even if the part) extends, the middle part in the length direction is not subject to the number measurement. Then, the number of fiber ends per unit area on the measurement target surface (basic surface or skeleton surface) of the fiber mass is calculated by the following formula. For each of the 10 fiber lumps, the number of fiber ends per unit area on each of the basic surface and the skeleton surface was measured according to the above procedure, and the average value of the plurality of measured values was calculated as the average value of the plurality of measured values at the fiber end on the measurement target surface. The number per unit area of.
Number of fiber ends per unit area on the measurement target surface (basic surface or skeleton surface) of the fiber mass (number / mm ² ) = number of fiber ends included in the rectangular region (1.2 × 0.6 mm) / Area of the rectangular area (0.72 mm ² )

When the basic surface 111 of the fiber mass 11 has a rectangular shape in a plan view as in the fiber mass 11A shown in FIG. 12A, the viewpoint of improving the uniform dispersibility of the fiber mass 11 in the absorbent core 40. Therefore, it is preferable that the short side 111a of the rectangular shape is equal to or shorter than the thickness of the absorber 4 containing the fiber mass 11 (11A).
The ratio of the length of the short side 111a to the thickness of the absorber 4 is preferably 0.03 or more, more preferably 0.08 or more, and preferably 1 or less, more preferably 0.5 or less as the former / the latter. Is.
The thickness of the absorber 4 (absorbent core 40) is preferably 1 mm or more, more preferably 2 mm or more, and preferably 10 mm or less, more preferably 6 mm or less.

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 at the time of specifying the outer shape of the fiber mass 11 described later.
When the basic surface 111 has a rectangular shape in a plan view as shown in FIG. 12A, the length L1 of the short side 111a is preferably 0.1 mm or more, more preferably 0.3 mm or more, still more preferably 0.5 mm. The above, preferably 10 mm or less, more preferably 6 mm or less, still more preferably 5 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 1 mm or more, further preferably 2 mm or more, and preferably 30 mm or less, more preferably 15 mm or less. More preferably, it is 10 mm or less.
As shown in FIG. 12, 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 plane-view circular basic surface 111 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. 8A, 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, more preferably 6 mm or less. is there.

FIG. 14 (a) shows an electron micrograph of an embodiment of the fiber mass 11, and FIG. 14 (b) shows a diagram schematically showing the fiber mass 11 according to the electron micrograph. There is. As shown in FIG. 14, the fiber mass 11 is configured to include a main body 110 and fibers 11F extending outward from the main body 110, and has a lower fiber density (unit area) than the main body 110. Those having an extended fiber portion 113 (with a small number of fibers per hit) can be included. The absorbent core 40 may also include a fiber mass 11 having no extended fiber portion 113, that is, a fiber mass 11 composed of only the main body portion 110. The extended fiber portion 113 may include a type of fiber end portion existing on each surface (basic surface 111, skeleton surface 112) of the fiber mass 11 described above, and is a fiber among the fiber end portions. It is a fiber end portion extending outward from each surface of the mass 11.

The main body 110 is a portion defined by the above-mentioned two opposing basic surfaces 111 and a skeleton surface 112 connecting both basic surfaces 111. The main body 110 is a portion that forms the main body of the fiber mass 11 and forms a fixed outer shape of the fiber mass 11, and various characteristics such as high flexibility, cushioning property, and compression recovery property of the fiber mass 11 are basic. It is largely due to the main body 110. On the other hand, the extended fiber portion 113 mainly contributes to the improvement of the entanglement between the plurality of fiber lumps 11 contained in the absorbent core 40 or between the fiber lumps 11 and the water-absorbent fiber 12F, and retains the absorbent core 40. In addition to being directly related to the improvement of shape, it can indirectly reinforce the action and effect of the main body 110 by affecting the uniform dispersibility of the fiber mass 11 in the absorbent core 40.

The main body 110 has a higher fiber density than the extended fiber 113, that is, the number of fibers per unit area is large. Further, usually, the fiber density of the main body 110 itself is uniform. The ratio of the main body 110 to the total mass of the fiber mass 11 is usually at least 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 85% by mass or more. The main body portion 110 and the extending fiber portion 113 can be distinguished by the work of specifying the outer shape, which will be described later.

The work of specifying the outer shape of the main body 110 of the fiber mass 11 included in the absorbent core 40 is the work of specifying the height difference of the fiber density (the number of fibers per unit area) and the fibers in the fiber mass 11 and its peripheral portion. This can be done by paying attention to the difference in the type and fiber diameter of the main body 110 and confirming the "boundary" between the main body 110 and the other parts. The main body 110 has a higher fiber density than the extending fiber portion 113 existing around the main body 110, and the synthetic fiber (typically thermoplastic fiber) which is a constituent fiber of the main body 110 is usually a water-absorbent fiber 12F (typically). Since it is qualitatively and / or dimensionally different from the cellulose-based fiber), even in the absorber 4 in which a large number of fiber lumps 11 and the water-absorbent fiber 12F are mixed, by paying attention to the above points, the said The boundaries can be easily confirmed. The boundary thus confirmed is the peripheral edge (side) of the basic surface 111 or the skeleton surface 112, and the basic surface 111 and the skeleton surface 112 are specified by the boundary confirmation work, and the main body 110 is specified. Will be done. Such boundary confirmation work can be carried out by observing the object (absorbent 4) at a plurality of observation angles as needed using an electron microscope.

As shown in FIG. 14, there is at least one extending fiber portion 113 around the main body portion 110, and the extending fiber portion 113 is outward from at least one of the basic surface 111 and the skeleton surface 112 which are the outer surfaces of the main body portion 110. It is composed of the constituent fibers 11F of the main body 110 extending to. In the fiber mass 11 shown in FIG. 10, a plurality of constituent fibers 11F protrude outward from the four sides 112a and 112b of the rectangular skeleton surface 112 in a plan view, and the fibers protrude from the main body 110. All the portions are extended fiber portions 113.

The form of the extended fiber portion 113 is not particularly limited. The extended fiber portion 113 may be composed of one fiber 11F, or may be composed of a plurality of fibers 11F as in the extended fiber bundle portion 113S described later. Further, the extending fiber portion 113 typically includes an end portion in the length direction of the fiber 11F extending from the main body portion 110, but in addition to or in place of such a fiber end portion, In some cases, a portion (intermediate portion in the length direction) other than both ends in the length direction of the fiber F may be included. That is, in the fiber mass 11, both ends of the constituent fibers 11F in the length direction are present in the main body 110, and the other parts, that is, the intermediate parts in the length direction extend outward from the main body 110 in a loop shape ( Where there is a possibility of protrusion), the extending fiber portion 113 in that case is configured to include such a loop-shaped protruding portion of the fiber 11F. In other words, of the extended fiber portions 113, those whose ends are exposed are one type of fiber end portions.

As described above, one of the main roles of the extended fiber portion 113 is to entangle the plurality of fiber lumps 11 contained in the absorber 4 or the fiber lumps 11 and the water-absorbent fiber 12F with each other. In general, the extension length of the extension fiber portion 113 from the main body 110 becomes longer, the thickness of the extension fiber portion 113 becomes thicker, or the number of extension fiber portions 113 included in one fiber mass 11. When the amount of entanglement increases, the connection between the entangled objects via the extending fiber portion 113 becomes stronger and the entanglement becomes difficult to be released, so that the predetermined effect of the present invention can be more stably achieved. Become.

When the fiber mass 11 is obtained by cutting the raw material fiber sheet 10bs into a fixed shape as shown in FIG. 13, the extended fiber portion 113 is present in a relatively large amount on the skeleton surface 112 which is the cut surface thereof. On the other hand, it does not exist at all on the basic surface 111, which is an uncut surface, or even if it exists, the number is smaller than that of the skeletal surface 112. As described above, the reason why the extended fiber portion 113 is unevenly distributed on the skeleton surface 112 which is the cut surface is that most of the extended fiber portion 113 is "fluff" generated by cutting the raw material fiber sheet. That is, since the skeleton surface 112 formed by cutting the raw material fiber sheet 10bs is entirely rubbed by a cutting means such as a cutter at the time of cutting, fluff made of the constituent fibers 11F of the sheet 10bs is likely to be formed, so-called fluffing. easy. On the other hand, since the basic surface 111, which is a non-cut surface, does not have friction with such a cutting means, it is difficult for fluff, that is, the extending fiber portion 113 to be formed.

The interval L1a (interval in the first direction D1, see FIG. 13) and the interval L2a (interval in the second direction D2, see FIG. 13) at the time of cutting the raw material fiber sheet 10bs are the formation of the extended fiber portion 113 described above. From the viewpoint of promotion and the like and from the viewpoint of ensuring the dimensions necessary for the fiber mass 11 to exert a predetermined effect, the thickness is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 30 mm or less. More preferably, it is 15 mm or less.

As shown in FIG. 14, the fiber mass 11 includes an extension fiber bundle portion 113S including a main body portion 110, more specifically, a plurality of fibers 11F extending outward from the skeleton surface 112 as a kind of extension fiber portion 113. What you have can be included. At least one of the extended fiber portions 113 included in the fiber mass 11 may be the extended fiber bundle portion 113S. The extension fiber bundle portion 113S is formed by gathering a plurality of fibers 11F extending from the skeleton surface 112, and has an extension length from the main body portion 110 skeleton surface 112 as compared with the extension fiber portion 113. Is characterized by a long point. The extending fiber bundle portion 113S may also be present on the basic surface 111, but typically exists on the skeletal surface 112 as shown in FIG. 14, and does not exist at all on the basic surface 111, or even if it exists. The number is less than the skeletal surface 112. The reason is the same as the reason why the extending fiber portion 113 mainly exists on the skeleton surface 112 which is the cut surface, and is as described above.

Since the fiber mass 11 has such an extended fiber bundle portion 113S which can be said to be a long, thick and large extended fiber portion 113, the fiber masses 11 or the fiber masses 11 and the water-absorbent fiber 12F The entanglement becomes stronger, and as a result, the predetermined effect of the present invention due to the presence of the fiber mass 11 becomes more stable. The extended fiber bundle portion 113S is easily formed by cutting the raw material fiber sheet 10bs (see FIG. 13) under the above-mentioned fluffy condition.

The extension length of the extension fiber bundle portion 113S from the main body 110, that is, the extension length from the skeleton surface 112 (cut surface) is preferably 0.2 mm or more, more preferably 0.5 mm or more, and It is preferably 7 mm or less, more preferably 4 mm or less. The extension length of the extension fiber bundle portion 113S can be measured in the work of specifying the outer shape of the fiber mass 11 (boundary confirmation work). Specifically, for example, a double-sided tape manufactured by 3M Co., Ltd. was attached to the surface of a transparent acrylic sample table with a microscope (50 magnification) manufactured by Keyence, and a fiber mass 11 was placed and fixed on the double-sided tape. Above, after specifying the outer shape of the fiber mass 11 according to the above-mentioned work of specifying the outer shape, the length of the extended portion of the fiber 11F extending from the outer shape is measured, and the measured extension is measured. The length of the minute is defined as the extension length of the extension fiber bundle portion 113S.

It is preferable that the plurality of constituent fibers 11F of the extended fiber bundle portion 113S are heat-sealed to each other. The heat-sealed portion of the extended fiber bundle portion 113S is usually in the length direction of the extended fiber bundle portion 113S as compared with the other portion (non-heat-fused portion) of the extended fiber bundle portion 113S. The transfer length (diameter when the cross section of the heat-sealed portion is circular) is long in the direction orthogonal to. Since the extended fiber bundle portion 113S has such a heat-sealed portion that can be said to be a large-diameter portion, the strength of the extended fiber bundle portion 113S itself is increased, and thereby through the extended fiber bundle portion 113S. The entanglement between the entangled fiber lumps 11 or between the fiber lumps 11 and the water-absorbent fiber 12F becomes stronger. Further, when the extended fiber bundle portion 113S has a heat-sealed portion, not only when the extended fiber bundle portion 113S is in a dry state but also when it is in a wet state by absorbing moisture. There is an advantage that the strength and shape retention of the extended fiber bundle portion 113S itself are increased. Due to such merits, when the absorbent core 40 is applied to the absorbent article, not only the absorbent core 40 is in a dry state, but also body fluids such as urine and menstrual blood excreted by the wearer are removed. Even when it is absorbed and becomes wet, the action and effect due to the presence of the above-mentioned fiber mass 11 can be stably exerted. Such an extended fiber bundle portion 113S having a heat-sealing portion can be used as the raw material fiber sheet 10bs in the manufacturing process of the fiber mass 11 as shown in FIG. 13, that is, the cutting step of the raw material fiber sheet 10bs of the fiber mass 11. It can be manufactured by using the above-mentioned "nonwoven fabric having a heat-sealed portion between synthetic fibers".

Synthetic fibers are used as the constituent fibers 11F of the fiber mass 11. Then, from the viewpoint of enabling the absorber 4 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, a fiber mass No. 11 preferably has a three-dimensional structure in which a plurality of thermoplastic fibers are heat-sealed to each other. Further, in order to obtain such a fiber mass 11 in which a plurality of heat-sealed portions are three-dimensionally dispersed, a synthetic fiber having heat-sealing property is preferable as the constituent fiber 11F of the fiber mass 11. As such a heat-sealing synthetic fiber, a thermoplastic fiber can be exemplified, and a non-water-absorbent thermoplastic fiber is particularly preferable. As described above, it is preferable that the extended fiber bundle portion 113S has a heat-sealed portion. However, by using a thermoplastic fiber as the constituent fiber 11F of the fiber mass 11, such an extended fiber bundle portion 113S It is also possible to obtain a preferable form of. 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. 13) may be similarly configured, and such a plurality of heats may be obtained. As described above, the raw material fiber sheet 10bs in which the fused portions are three-dimensionally dispersed can be produced 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 non-water-absorbent 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; polyamides such as nylon 6 and nylon 66; polyvinylidene acid, Examples thereof include polymethacrylic acid alkyl ester, polyvinyl chloride, polyvinylidene chloride and the like, 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 combining 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.

In addition, when the absorbent body (absorbent core) to be measured is used as a constituent member of another article such as an absorbent article, and the absorbent body is taken out and evaluated and measured, the absorbent body is an adhesive. When it is fixed to other components by fusion, etc., the adhesive force is removed from the fixed part by blowing cold air from a cold spray within the range that does not affect the contact angle of the fibers. Take out from. This procedure is common to all measurements herein.

Further, it is preferable that the constituent fibers 11F constituting the fiber mass 11 have a property of being non-absorbent, that is, having a property of being difficult to absorb water (body fluid such as urine and menstrual blood). This is in stark contrast to the water-absorbent fiber 12F used in combination with the fiber mass 11 having literal water absorption. Since the fiber 11F is a non-water-absorbent fiber having poor water absorption, the presence of the above-mentioned fiber mass 11 occurs not only when the absorbent core 40 is in a dry state but also when it is in a wet state by absorbing body fluid. The resulting action and effect (improvement effect such as shape retention, flexibility, cushioning property, compression recovery property, and resistance to twisting) will be stably exhibited. Therefore, the raw material fiber is preferably a non-water-absorbent synthetic fiber.

In the present specification, the term "water absorption" is easily understood by those skilled in the art, for example, pulp is said to be water absorbent. Similarly, it can be easily understood that thermoplastic fibers are non-absorbent. On the other hand, the degree of water absorption of the fiber can be compared with the relative difference in water absorption by the value of the water content measured by the following method, and a more preferable range can be defined. As the water-absorbent fiber, the water content is preferably 6% or more, and more preferably 10% or more. On the other hand, the non-water-absorbent fiber preferably has such a water content of less than 6%, more preferably less than 4%.

<Measurement method of moisture content>
The water content was calculated by applying the water content test method of JIS P8203 mutatis mutandis. That is, after the fiber sample was allowed to stand in a test room having a temperature of 40 ° C. and a relative humidity of 80% RH for 24 hours, the weight W (g) of the fiber sample before the absolute drying treatment was measured in the room. Then, it was allowed to stand in an electric dryer having a temperature of 105 ± 2 ° C. (for example, manufactured by Isuzu Motors Ltd.) for 1 hour to perform an absolute drying treatment of the fiber sample. After the absolute drying treatment, Si silica gel (for example, Si silica gel (for example,)) is used in a standard state laboratory at a temperature of 20 ± 2 ° C. and a relative temperature of 65 ± 2% with the fiber sample covered with Saran Wrap (registered trademark) manufactured by Asahi Kasei Corporation. Toyoda Kako Co., Ltd. is placed in a glass desigator (for example, manufactured by Tech Jam Co., Ltd.) and allowed to stand until the temperature of the fiber sample reaches 20 ± 2 ° C. Then, the constant amount W'(g) of the fiber sample is weighed, and the water content of the fiber sample is obtained by the following formula. Moisture content (%) = (W-W'/ W') x 100

As the water-absorbent fiber 12F, a water-absorbent fiber conventionally used as a material for forming an absorber of this kind of absorbent article can be used. For example, wood pulp such as coniferous pulp and broadleaf pulp, cotton pulp and hemp. Natural fibers such as non-wood pulp such as pulp; modified pulp such as cationized pulp and marcelled pulp can be mentioned, and one of these can be used alone or in combination of two or more. From the viewpoint that the main role of the water-absorbent fiber 12F is to improve the liquid absorbency of the absorber 4, the water-absorbent fiber 12F is particularly preferably a cellulosic fiber.

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 napkin 1 shown in FIG. 1, the surface longitudinal recessed portion 7X and the surface lateral concave recessed portion 7Y constituting the surface recessed portion 7 are connected at the end portions in the length direction thereof, and the surface recessed portion 7 as a whole is closed. Although an annular shape was formed, the concave portions constituting the surface concave portion 7 do not have to be connected to each other, and the surface vertical concave portion 7X and the surface horizontal concave portion 7Y are arranged close to each other with a gap. You may. The same applies to the back surface recessed portion 8 that overlaps the front surface recessed portion 7 in a plan view.
The absorbable 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 sanitary napkins, sanitary shorts and fastenings. So-called deployable disposable diapers with tape, pants-type disposable diapers, incontinence pads and the like are included.

1 Sanitary napkin (absorbent article)
F Front area M Vertical center area R Rear area 2,2A Front sheet 21 Convex part 22 Concave part 3 Back side sheet 4,4A, 4B, 4C, 4D, 4E, 4F Absorber 40 Absorbent core 41 Core wrap sheet 42 Grooved concave part 42X Vertical recess 42Y Horizontal recess 43 Small absorption part 44 Continuous layer 45 Skin facing surface of absorber or absorbent core 46 Non-skin facing surface of absorber or absorbent core 5 Absorbent body 6 Side sheet 7, 7X, 7Y Surface concave Part 8,8X, 8Y Backside concave part 9 Low density part 11 Fiber mass 11F Constituent fiber of fiber mass (synthetic fiber)
110 Main body 111 Basic surface 112 Skeleton surface 113 Extended fiber part 113S Extended fiber bundle part 12F Water-absorbent fiber 13 Water-absorbent polymer

Claims (11)

It has a vertical direction corresponding to the front-back direction of the user and a horizontal direction orthogonal to the vertical direction, and with respect to the vertical direction, a vertical central region arranged to face the excretory portion of the user and a vertical direction rather than the vertical central region. An absorbent article having an anterior region arranged on the front side and a rear region arranged on the rear side in the vertical direction from the vertical central region, and having an absorbent core for absorbing and holding body fluid.
The absorbent core is formed with a groove-like recess having an opening on at least one of the skin-facing surface and the non-skin-facing surface of the absorbent core and extending in a predetermined direction. The portion that overlaps the groove-shaped recess in a plan view has a lower basis weight than the periphery thereof.
The absorbent core is an absorbent article containing a fiber mass containing synthetic fibers and a water-absorbent fiber. The absorbent core has a continuous layer in which the groove-like recess is not formed over the entire surface direction of the absorbent core in a part of the thickness direction of the absorbent core, and the fiber is formed in the continuous layer. The absorbent article according to claim 1, wherein the lump and the water-absorbent fiber are present. Claimed that the continuous layer is unevenly distributed on the skin-facing surface side or the non-skin-facing surface side of the absorbent core, and the depth of the groove-shaped recess is 40% or more and 98% or less of the thickness of the absorbent core. Item 2. The absorbent article according to item 2. Claims 1 to 3 show that, at least in the vertical central region, the non-skin facing surface side of the absorbent core has a larger mass per unit area of the fiber mass than the skin facing surface side of the absorbent core. The absorbent article according to any one item. 4. Also in the front region and the rear region, the non-skin facing surface side of the absorbent core has a larger mass per unit area of the fiber mass than the skin facing surface side of the absorbent core. Absorbent article described in. The absorbency according to any one of claims 1 to 5, wherein in the absorbable core, the longitudinal center region has a larger mass per unit area of the fiber mass than the front region and the rear region. Goods. The absorbent article according to any one of claims 4 to 6, wherein the absorbent core contains 90% by mass or more of all the fiber lumps contained in the absorbent core in the vertical central region. A surface sheet provided on the skin-facing surface side of the absorbent core, and the surface sheet and the surface recessed portion in which the absorbent core is integrally recessed on the non-skin-facing surface side of the absorbent core is at least said. It is formed in the vertical center area and
In the vertical central region, the mass of the fiber mass per unit area differs between the skin-facing surface side and the non-skin-facing surface side of the absorbent core.
The surface recessed portion overlaps with the fiber mass in a plan view, and in the vertical central region, the mass per unit area of the fiber mass extends to a region different from the skin facing surface side of the absorbent core. The absorbent article according to any one of claims 1 to 7. The surface recessed portion extends in the vertical direction through both lateral portions of the vertical central region.
In the vertical central region, the surface recessed portions on both sides in the lateral direction and the region sandwiched between them are per unit area of the fiber mass as compared with the laterally outward sides of the surface recessed portions on both sides in the lateral direction. The absorbent article according to claim 8, which has a large mass. The fiber mass comprises two opposing basic surfaces and a skeletal surface connecting the two basic surfaces.
The absorbency according to any one of claims 1 to 9, wherein the number of fiber ends present on each of the basic surface and the skeletal surface per unit area is larger in the skeletal surface than in the basic surface. Goods. The groove-shaped recess has a vertical recess extending in the vertical direction and a horizontal recess extending in a direction intersecting the vertical recess.
The absorption according to any one of claims 1 to 10, wherein the surface side of the absorbent core in which the opening of the vertical recess and the opening of the horizontal recess are formed is divided into a plurality of small absorption portions. Sex goods.