TWI745639B - Absorbent articles - Google Patents

Abstract

The absorbent article (1) of the present invention includes an absorber (4) and a front sheet (2) arranged on the skin facing side of the absorber (4). The absorbent body (4) is composed of a liquid-absorbent absorbent core (40) and a core-coated material (41) covering the skin facing surface of the absorbent core (40). The absorbent core (40) comprises a water-absorbent fiber (12F), and a fiber block (11) containing a weakly water-absorbent fiber (11F) having lower water absorption than the water-absorbent fiber (12F). The ratio of the liquid diffusion area of the absorbent core (40) to the liquid diffusion area of the core-coating material (41) is 0.7 or more in terms of the former/the latter.

Description

Absorbent articles

The present invention relates to an absorbent article such as a menstrual sanitary napkin.

Generally speaking, disposable diapers, menstrual sanitary napkins and other absorbent articles include a front sheet that is relatively close to the wearer's skin, a back sheet that is relatively far away from the wearer's skin, and an intermediary. It is composed of an absorbent body between two sheets. Typically, the absorbent body includes an absorbent core constituting the main body of the absorbent body, and a core-cladding material covering the surface of the absorbent core. In most cases, the absorbent core is made of absorbent fibers such as wood pulp. The main body is further composed of water-absorbing polymer particles. With regard to absorbents used in absorbent articles, improvement of various properties such as flexibility (cushioning properties), compression recovery properties, and shape retention properties is a major issue.

As an improvement technique of an absorber, for example, Patent Document 1 describes an absorber that contains thermoplastic resin fibers and cellulose-based water-absorbent fibers, and the thermoplastic resin fibers are placed on the surface of the absorbent body on the side of the front sheet and the absorber. Both of the surface of the back sheet side of the body are exposed. 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 cellulose-based water-absorbent fibers, and is therefore relatively soft and hard to wrinkle.

In addition, Patent Document 2 describes an absorbent body that contains a non-woven fabric sheet that contains thermally fusible fibers and is bonded to the fibers in advance to give a three-dimensional structure, and water-absorbent fibers. The three-dimensional structure of the non-woven fabric sheet is manufactured by crushing the non-woven fabric into fragments using a crushing method such as a shredder crushing method. Therefore, due to this manufacturing method, it is as described in Figures 1 and 3 of the same document. It has an indefinite shape and does not substantially have a part that is regarded as a plane. In Patent Document 2, as a preferred form of the absorber described in the same document, a non-woven fabric sheet formed by heat-fusing each other is described. According to the absorbent body described in Patent Document 2, since the nonwoven fabric sheet has a three-dimensional structure, voids are formed inside the absorbent body, and the recovery performance when absorbing moisture is improved. As a result, the water absorption performance is improved.

In addition, Patent Document 3 describes a microfiber web having a relatively dense microfiber core and fibers or fiber bundles extending from the core to the outside, and also describes that the microfiber web is combined with wood pulp or water-absorbing The non-woven fiber web formed by mixing the flexible polymer particles can be used as an absorber for absorbent articles. This fine fiber web is produced by pulling or tearing off a raw material sheet such as a nonwoven fabric, and has an indeterminate shape like the nonwoven fabric sheet described in Patent Document 2, and has substantially no part that is regarded as a flat surface.

In addition, Patent Document 4 describes that when the absorbent body contains a water-absorbent polymer, if the absorbent body absorbs liquid and swells, it will be sealed by the front sheet and back sheet disposed above and below the absorbent body. To prevent the swelling of the water-absorbent polymer, in order to solve this problem, a buffer layer with high compression/compression recovery and liquid permeability is interposed between the front sheet and the absorbent body. In addition, it is described as a non-woven fabric fragment The buffer layer is constituted by an assembly, and the thickness of the buffer layer is 10-40 mm. In Patent Document 4, there is no specific description about the shape of the fragments of the non-woven fabric used for the cushion layer, etc.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2015-16296

[Patent Document 2] Japanese Patent Laid-Open No. 2002-301105

[Patent Document 3] Japanese Patent Laid-Open No. 1-156560

[Patent Document 4] Japanese Patent Laid-Open No. 2003-52750

The present invention relates to an absorbent article, which has a longitudinal direction corresponding to the front and rear directions of the wearer and a transverse direction orthogonal thereto, and is provided with an absorber and a front sheet disposed on the skin facing side of the absorber. The absorbent body includes a liquid-absorbent absorbent core and a core-clad material covering the skin facing surface of the absorbent core. The absorbent core includes: water-absorbent fibers; and fiber blocks, which include water-absorbent fibers. It is a weakly absorbent fiber with lower properties than the absorbent fiber. The ratio of the liquid diffusion area of the absorbent core measured by the following method to the liquid diffusion area of the core-coated sheet measured by the following method is 0.7 or more.

<Measurement method of liquid diffusion area>

On an inclined surface having an angle of 45° with respect to the horizontal plane, the measurement object is fixed so that the opposite side of the skin faces the inclined surface, and it takes 23 seconds to inject 1.5 g of defibrinated horse blood into the opposite surface of the measured object’s skin. , After standing for 3 minutes, perform the operation of injecting the same amount of defibrinated horse blood into the same injection site again for the same time. This defibrillated horse blood was injected and placed six times repeatedly, and a total of 9 g of defiberized horse blood was injected into the measurement object. After the injection operation is completed, the diffusion area of the defibrinated horse blood in the opposite surface of the skin of the measurement object is measured, and it is taken as the liquid diffusion area of the measurement object.

1: Sanitary napkin

2: Front sheet

3: Back sheet

4: Absorber

5: Absorbent body

5W: Wing

6: Side sheet

7: Depressed part

10bs: raw fiber sheet

11: Fiber block

11A: Fiber block

11B: Fiber block

11F: Fiber

11Z: Overlap

12F: Absorbent fiber

40: Absorbent core

41: package chip material

100: measuring station

100a: inclined plane

101: Acrylic resin board

110: body part

111: Fundamentals

111a: short side

111b: Long side

112: Skeleton surface

113: Extend the fiber part

113S: Extend the fiber bundle part

A: Front area

B: Vertical central area

BL: Border

C: Rear area

D1: 1st direction

D2: 2nd direction

F: External force

L1: length

L1a: interval

L2: length

L2a: interval

S: Measurement object

T: thickness

X: portrait

Y: horizontal

Z: thickness direction

Fig. 1 is a plan view schematically showing a part of the skin facing side (front sheet side) of the menstrual sanitary napkin as an embodiment of the absorbent article of the present invention.

Fig. 2 is a schematic cross-sectional view of the I-I line section of Fig. 1.

Figure 3 is a schematic diagram of a part of the absorbent core of the absorbent article shown in Figure 1 Stereograph.

Fig. 4 is a diagram schematically showing the deformed state of the absorbent core shown in Fig. 3 when compressed.

Figures 5(a) and 5(b) of Figure 5 are respectively schematic perspective views of the main body of the fiber block of the present invention.

Fig. 6 is an explanatory diagram of the method of manufacturing the fiber block of the present invention.

Fig. 7(a) is an electron micrograph of an example of the fiber mass of the present invention (observation magnification 25 times), and Fig. 7(b) schematically shows the fiber mass of the electron micrograph as shown in Fig. 2. A diagram of the fiber block contained in the absorbent body.

Fig. 8 is an explanatory diagram of the measuring method of the liquid diffusion area.

The absorbent body described in Patent Document 1 contains synthetic fibers (thermoplastic resin fibers) in addition to cellulose-based water-absorbent fibers, and therefore has higher rigidity than an absorbent body containing only cellulose-based water-absorbent fibers as constituent fibers. Therefore, improvement of various properties such as cushioning properties and compression recovery properties can be expected. However, the plurality of synthetic fibers contained are independent of each other and do not form an aggregated block. Therefore, the improvement effect of these properties is not sufficient. Therefore, in the application In the case of absorbent articles, wrinkles are likely to occur and the conformability may become insufficient, especially after the absorption of body fluids such as urine and menstrual blood, the occurrence of such disadvantages is more prominent.

On the other hand, the synthetic fibers contained in the absorbent bodies described in Patent Documents 2 to 4 are all synthetic fiber aggregates called nonwoven fabric sheets or microfiber webs, so improvement of cushioning properties and the like can be expected. However, according to the findings of the present inventors, if a plurality of such weakly absorbent synthetic fiber aggregates are contained in an absorbent body, the liquid permeability of the absorbent body will decrease, and as a result, the absorbent body will pass through the front sheet and reach the absorbent body. The body fluid on the opposite side of the skin (chip-coated material) is difficult to be introduced to the inhalation. In the body (absorbent core), a large amount of body fluid remains on the opposite surface of the absorbent body, which causes the uncomfortable skin to feel sticky or moist. Patent Documents 2 to 4 do not describe the problem of absorbents of synthetic fiber aggregates due to weak water absorption, and there is no technology for solving the problems while utilizing the advantages of synthetic fiber aggregates.

Therefore, the present invention relates to an absorbent article having an absorbent body with high liquid permeability to an absorbent core and excellent cushioning properties.

Hereinafter, the present invention will be described with reference to the drawings and based on its preferred embodiments. Fig. 1 and Fig. 2 show a menstrual sanitary napkin 1 as an embodiment of the absorbent article of the present invention. The sanitary napkin 1 is equipped with: an absorbent body 4 that absorbs and retains body fluids; a liquid-permeable front sheet 2 that is arranged on the opposite side of the skin of the absorbent body 4 and can be in contact with the wearer's skin; and liquid is difficult to permeate The sexual back sheet 3 is arranged on the non-skin facing side of the absorbent body 4. As shown in Fig. 1, the sanitary napkin 1 has a longitudinal direction X corresponding to the front and back direction of the wearer and extending from the wearer’s ventral side to the back side through the crotch, and a transverse direction Y orthogonal to it. In addition, in the longitudinal direction X, Divided into the following three areas: the longitudinal central area B, which contains the excretion part opposite to the wearer’s vaginal opening and other excretion parts (excretion point); the front area A, which is arranged at the opposite part of the excretion part It is closer to the ventral side (front side) of the wearer; and the rear area C is arranged on the back side (rear side) of the wearer than the opposite part of the excretory part.

In this specification, the "skin facing surface" refers to the surface of the absorbent article or its constituent members (for example, absorber 4) facing the wearer's skin when worn, that is, relatively close to the wearer's skin The "non-skin facing surface" refers to the surface of the absorbent article or the absorbent article of its constituent members that faces the side opposite to the skin side when worn, that is, the side relatively far away from the wearer's skin. Furthermore, the "wearing time" mentioned here means the state of maintaining the usual proper wearing position, that is, the correct wearing position of the absorbent article.

As shown in Figure 1, the sanitary napkin 1 has: an absorbent body 5, which is a long shape in the longitudinal direction X; Each of the two sides of B along the longitudinal direction X extends to the outer side of the lateral direction Y. The absorbent body 5 is the main body part of the sanitary napkin 1. It includes the front sheet 2, the back sheet 3, and the absorbent body 4, and is divided into 3 of the front area A, the vertical center area B, and the rear area C in the longitudinal direction X. Regions.

Furthermore, when the absorbent article has wings like sanitary napkin 1, the longitudinal center area in the absorbent article of the present invention means the longitudinal direction (length direction, X direction in the figure) of the absorbent article The area with wings, taking the sanitary napkin 1 as an example, is an area sandwiched by the root of one wing 5W along the longitudinal direction X and the root of the other wing 5W along the longitudinal direction X. In addition, the longitudinal center area in the absorbent article without wings means the area in the middle when the absorbent article is divided into thirds in the longitudinal direction.

The absorber 4 is constituted by a liquid-absorbent core 40 and a liquid-permeable cored sheet 41 covering at least the skin-facing surface of the absorbent core 40. The absorbent core 40, like the absorbent main body 5, has a shape that is longer in the longitudinal direction X in a plan view as shown in FIG. The width direction of the body 40 is consistent with the transverse direction Y of the sanitary napkin 1. The absorptive core 40 and the core covering material 41 may be joined by an adhesive such as a hot-melt adhesive.

In the sanitary napkin 1, the core-covered material 41 is a continuous sheet having a width that is more than two times and three times the length of the transverse direction Y of the absorbent core 40, as shown in FIG. 2, covering the absorbent core The entire area of the skin-facing surface of the body 40 extends from both sides of the absorbent core 40 along the longitudinal direction X to the outer side of the transverse direction Y, and the extension part rolls down below the absorbent core 40 and is covered The whole area of the non-skin facing surface of the absorbent core 40. Furthermore, in the present invention, the core-wrapped material may not be such a single sheet, for example, may include a sheet of muscle on the skin facing surface covering the absorbent core 40 The skin-side core-encapsulation material and two sheets of the non-skin-side core-encapsulation material that are different from the skin-side core-encapsulation material and cover the non-skin-facing surface of the absorbent core 40 are formed.

As shown in FIG. 2, the surface sheet 2 covers the entire area of the skin-facing surface of the absorber 4. On the other hand, the back sheet 3 covers the entire area of the non-skin facing surface of the absorber 4, and further extends from the both sides of the absorber 4 in the longitudinal direction X to the outer side in the transverse direction Y, and the following side sheet 6 forms a side flap part (including the part extending from the absorbent body 4 to the outer side of the transverse direction Y). The back sheet 3 and the side sheet 6 are joined to each other at the extending portions from the both sides of the absorber 4 along the longitudinal direction X by a well-known joining method such as an adhesive, heat sealing, and ultrasonic sealing. Each of the front sheet 2 and the back sheet 3 and the absorber 4 may be joined by an adhesive. As the front sheet 2 and the back sheet 3, various sheets previously used for absorbent articles such as menstrual sanitary napkins can be used without particular limitation. For example, as the top sheet 2, a single-layer or multilayer structure of non-woven fabric, or an apertured film, etc. can be used. As the back sheet 3, a moisture-permeable resin film or the like can be used.

As shown in FIG. 1, the above-mentioned side flaps largely protrude to the outside of the transverse direction Y in the longitudinal central region B, whereby a pair of flaps 5W and 5W are extended on the left and right sides of the absorptive main body 5 in the longitudinal direction X. The wing portion 5W has a substantially trapezoidal shape with a lower bottom (longer than the upper bottom side) on the side of the absorbent body 5 in a plan view as shown in FIG. 1, and the wing portion 5W is formed on its non-skin facing surface It is fixed to the wing adhesive part (not shown) of clothing such as shorts. The wing part 5W is folded back to the non-skin facing surface (outer surface) side of the crotch part of clothing such as shorts and used. The wing part adhesive part is covered with a release sheet (not shown) containing a film, non-woven fabric, paper, etc. before use. In addition, on the skin-facing surface of the absorbent body 5, that is, the two sides along the longitudinal direction X in the skin-facing surface of the front sheet 2, a pair of side sheets 6, 6 are in contact with the absorbent body 4 in a plan view. The left and right side portions in the longitudinal direction X are overlapped and arranged over the entire length of the absorbent body 5 in the longitudinal direction X. The pair of side sheets 6 and 6 are respectively joined by a bonding line not shown in the figure extending in the longitudinal direction X by a well-known bonding method such as an adhesive. To other components such as the front sheet 2.

As shown in FIGS. 1 and 2, on the skin-facing surface of the absorbent body 4, there are partially formed recesses integrally depressed with the core-coating material 41 and the absorbent core toward the non-skin-facing surface of the absorbent body 4 7. The depression 7 is formed by squeezing the sanitary napkin 1 from its skin-facing surface, that is, the surface sheet side, and it may also be referred to as a "squeezing part" in terms of its forming method. As the pressing process, a known method can be used. For example, embossing with or without heat, ultrasonic embossing, and the like can be cited. Due to the method of forming the depressed portion 7, the surface sheet 2, the core covering sheet 41, and the absorbent core 40 are integrally depressed toward the non-skin facing surface side (the back sheet 3 side) of the absorbent core 40. In addition, the depressed portion 7 has a higher density than its peripheral portion (non-formed portion of the depressed portion 7) due to its forming method. That is, the absorptive main body 5 has a high-density portion corresponding to the recessed portion 7 and a low-density portion corresponding to the non-recessed portion. At the bottom of the recessed portion 7, the top sheet 2, the core-clad sheet 41, and the absorbent core 40 may be thermally melted and integrated.

As shown in FIG. 1, the recess 7 is formed at least in the longitudinal central region B. More specifically, the portion from the front region A near the longitudinal center region B to the rear region C near the longitudinal center region B is in the longitudinal direction X On continuous. In the sanitary napkin 1, the recessed portion 7 is linear in the top view as shown in FIG. 1, and the linear recess 7 is closed loop in the plan view. The ring-shaped recess 7 has a shape that is longer in the longitudinal direction X in a plan view, and the length direction thereof is consistent with the longitudinal direction X. The ring-shaped recess 7 is formed in each of the front area A and the rear area C in a U-shape or an arc shape that protrudes toward the outside of the longitudinal direction X, and the top of the U-shape or arc is located in the transverse direction Y of the sanitary napkin 1. Of the center. In addition, the ring-shaped recess 7 is formed in the longitudinal center region B as a pair of left and right lines extending in the longitudinal direction X. In this way, the recessed portion 7 is formed so as to surround the center portion of the vertical center region B in the horizontal direction Y.

In the sanitary napkin 1, the depth of the recessed portion 7 (the depth from the non-recessed skin facing surface in the front sheet 2) becomes constant over the entire length in the longitudinal direction. The depth of the depression 7 can be Set to the same range as the depth of the leak-proof groove in this absorbent article, usually about 1~10mm. As an effect that can be expected by the formation of the depressed portion 7, for example, suppression of the diffusion of the liquid in the plane direction of the absorber 4, especially in the lateral direction Y, prevention of wrinkles of the absorber 4, and the like. Furthermore, the shape, arrangement, etc. of the linear depressions 7 are not limited to those shown in the figure, and can be set in the same way as those called leak-proof grooves in such absorbent articles. The top view shape includes straight lines and/or curves. For the structure, each line may be a continuous line or a dashed line (a form in which two types of parts with different depths are alternately arranged in the direction in which the linear depressions extend).

As one of the main characteristic parts of the sanitary napkin 1, the absorbent core 40 can be cited. FIG. 3 shows a part of the absorbent core 40 (non-formed part of the recessed part 7). As shown in FIGS. 2 and 3, the absorbent core 40 includes a fiber block 11 containing a plurality of fibers (weakly absorbent synthetic fibers) 11F, and a water-absorbent fiber 12F. The fiber block 11 is a fiber assembly in which the fibers 11F are deliberately aggregated in a block shape to be integrated. In contrast, the water-absorbent fibers 12F are not deliberately integrated and are present in the absorbent core 40 in a state where they can exist independently. . The fiber block 11 mainly contributes to the improvement of the flexibility, cushioning properties, compression recovery properties, and shape retention properties of the absorbent core 40. On the other hand, the water-absorbent fiber 12F mainly contributes to the improvement of the liquid absorbency and shape retention of the absorbent core 40. In addition, the absorbent core 40 can also be referred to as the absorbent body 4 itself, and the following description of the absorbent core 40 is appropriately used as the description of the absorbent body 4 unless otherwise specified. That is, the present invention includes the case where the absorber does not contain the core-cladding material and is formed only by the absorbent core. In this case, the absorber and the absorbent core have the same meaning.

In this specification, "fiber block" refers to a fiber assembly in which a plurality of fibers are gathered to form a single unit. As the form of the fiber block, for example, a sheet divided from a synthetic fiber sheet having a fixed size can be cited. As the fiber block, it is particularly preferable to select a non-woven fabric as a synthetic fiber sheet and cut from the non-woven fabric into a non-woven fabric sheet of a specific size and shape.

In this way, the sheet-like fiber block, which is a preferred embodiment of the fiber block of the present invention, is not constructed in a way that a plurality of fibers are gathered to form the sheet, but is made of a fiber sheet (preferably Non-woven fabric) is cut and manufactured (refer to Figure 6). The plurality of fiber blocks contained in the absorbent body of the present invention are a plurality of sheet-like fiber blocks with higher shape stability than those of the prior art manufacturers such as Patent Documents 1 and 2.

However, as described in Patent Documents 1 to 4, absorbent cores comprising aggregates of weakly water-absorbent synthetic fibers have low liquid permeability as described above. Therefore, with regard to absorbents using them, body fluids tend to remain in the coating. The skin-facing surface of the absorbent core is the skin-facing surface of the core-coated core material. As a result, there is a risk of causing uncomfortable skin to feel sticky or moist. In order to solve this problem caused by the use of weakly water-absorbent fibers, the present inventors have conducted various studies and obtained the following insights: an effective method is to wrap the skin-side core material in the absorbent body that is usually the first in contact with body fluids. The liquid diffusibility in the surface direction is set to a specific range in relation to the liquid diffusibility in the surface direction of the absorbent core that abuts on the skin-side core covering material.

Based on the above findings, in the sanitary napkin 1, the liquid diffusion area of the absorbent core 40 measured by the above-mentioned <Method for Measuring Liquid Spreading Area> and the liquid diffusion area of the skin-side core-encapsulating material 41 measured by the same measuring method The ratio (hereinafter, also referred to as "liquid diffusion area ratio") of the former/the latter is set to 0.7 or more. If the liquid diffusion area ratio is 0.7 or more, the movement of body fluids from the skin-side core covering material 41 to the absorbent core 40 is easy, and body fluids are not likely to remain on the skin facing surface of the skin-side core covering material 41, which can reduce The skin feels sticky or moist for comfort. From the viewpoint of smoother movement of body fluids from the skin-side core covering material 41 to the absorbent core 40, the liquid diffusion area ratio is preferably 0.75 or more, more preferably 0.8 or more, and more preferably 2.0 or less , And more preferably 1.5 or less.

Referring to FIG. 8, the above-mentioned "Method for Measuring Liquid Spreading Area" is supplemented, and the measurement object S (absorbent core, core-clad material) is set to have a quadrilateral shape in plan view of 240 mm×75 mm. The measuring table 100 used for the measurement has an inclined surface 100a whose angle θ formed with the horizontal plane is 45°. The measuring object S is placed on the inclined surface 100a so that the skin facing surface and the inclined surface 100a face the inclined surface 100a, and the acrylic resin plate 101 having an area larger than the thickness of the measuring object S by 3 mm is placed on the measuring object S. As the simulated blood injected into the defibrinated horse blood system of the measurement target S, a type B viscometer (manufactured by Toki Sangyo Co., Ltd., model TVB-10M, measurement conditions: rotor No. 19, 30 rpm, 25° C., 60 seconds) was used The measured viscosity is 8mPa. s person. As such defibrillated horse blood, for example, defibrillated horse blood manufactured by NIPPON BIOTEST Co., Ltd. can be used, and the viscosity can be adjusted to the above-mentioned specific range by adjusting the ratio of blood cells and plasma as necessary. The injection position of defibrinated horse blood in the measurement object S is set to the center of the skin facing surface of the measurement object S (the part shown by the arrow in Fig. 8), and a microtube pump (not shown in the figure) (Tokyo Rika Instruments Co., Ltd.) Co., Ltd.) injection. A tube (not shown) is connected to the pump, and the end of the tube on the side opposite to the connection side of the pump is connected to the measurement object S on the slope 100a, and defibrinated horse blood is injected into the measurement object S through the tube . The diffusion area of the defibrinated horse blood in the skin facing surface of the measurement object S can be transferred by using an OHP (Overhead projector) sheet to transfer the distribution area of the defibrinated horse blood in the measurement object S, and according to Conventionally, this OHP sheet is processed and measured using image analysis software Nexus NewQube (manufactured by Nexus Corporation).

In order to set the liquid diffusion area ratio to 0.7 or more as described above, it is necessary to think about the composition of both or one of the absorbent core 40 and the skin-side core covering material 41. Finding a way to improve the liquid permeability of the skin-side core-encapsulating material 41 is particularly effective. From this viewpoint, the skin-side core covering material 41 is preferably a porous sheet mainly composed of pulp. Furthermore, the key in this manual The description of "Skin-side core covering material" is also applicable to one continuous sheet, that is, other parts of the core covering material 41, unless otherwise specified. For example, the non-skin facing surface that forms the absorbent body 4 is the interposition arrangement The non-skin side core-covered material between the back sheet 3 and the absorbent core 40.

As the above-mentioned porous sheet which is preferable as the skin-side core covering material 41, a pulp sheet mainly composed of pulp can be exemplified. As the pulp sheet, paper produced by a wet papermaking method is typical. As the main component of the porous sheet, namely the pulp, cellulosic fibers can be used. Examples include: conifer sun-dried kraft pulp (NBKP), hardwood sun-dried kraft pulp (LBKP), and conifer sun-dried sulfite pulp ( Wood pulp such as NBSP), thermo-mechanical pulp (TMP); bast fibers such as paper mulberry, scented, sharo, etc.; non-wood pulp such as chao, bamboo, kenaf, hemp, etc., can be used alone or in combination Use two or more kinds. The content of the pulp in the porous sheet is preferably 10% by mass or more, and more preferably 50% by mass or more. The porous sheet may also contain components other than pulp or other components. Examples of the other components include fillers such as talc, dyes, coloring pigments, paper strength enhancers, antibacterial agents, and pH adjusters. , Yield improvers, water resistance agents, defoamers, etc., which are generally used as raw materials or additives for papermaking, can be used alone or in combination of two or more.

Moreover, from the viewpoint of improving the liquid permeability of the skin-side core-encapsulation material 41 (the above-mentioned porous sheet), the density of the skin-side core-encapsulation material 41 is preferably set to 0.1 g/m ³ or less, and particularly preferably Set to 0.08 g/m ³ or less. Furthermore, it is preferable that the density of the skin-side core covering material 41 is preferably 0.02 g/m ³ or more, and more preferably 0.04 g/m ³ or more, because it is easy to maintain sufficient sheet strength.

In addition, from the viewpoint of the balance between liquid permeability and strength, the basis weight of the skin-side core covering material 41 (the above-mentioned porous sheet) is preferably 5 g/m ² or more, and more preferably 10 g/m ² or more. In addition, it is preferably 50 g/m ² or less, and more preferably 30 g/m ² or less.

In the sanitary napkin 1, as described above, as shown in FIGS. 1 and 2, the core-coated material 41 (more specifically, the skin-side core-coated material 41) and the absorbent body 4 are formed on the skin-facing surface of the absorbent body 4 The depressed portion 7 that the sexual core 40 is integrally depressed toward the non-skin facing surface of the absorbent body 4. At this time, with this configuration, the shape of the absorbent body 4 is affected by the body pressure or movement of the wearer of the sanitary napkin 1 It becomes more stable, and it is expected that the conformability of the sanitary napkin 1 will be further improved. In addition, only a part of the absorbent body 4 (absorbent core 40) is formed with the depressed portion 7. As described below, the non-formed portion of the depressed portion 7, which occupies most of the absorbent core 40, is formed by intertwining constituent fibers. The shape retention property is due to this situation and so on. It is soft and has cushioning properties. Therefore, the sanitary napkin 1 can substantially directly show the characteristics of the non-formed portion of the recessed portion 7. From the viewpoint of the balance between the shape stability and cushioning properties of the absorbent body 4, the ratio of the total area of the depressed portion 7 to the total area of the skin facing surface of the absorbent body 4 (absorbent core 40) (the depressed portion occupies Rate) is preferably 3% or more, more preferably 5% or more, and more preferably 97% or less, and still more preferably 95% or less.

In addition, in the sanitary napkin 1, as shown in FIG. 1, the recessed portion 7 is formed to surround the center portion of the vertical center region B in the transverse direction Y, thereby further improving the shape stability of the center portion of the vertical center region B sex. The central part of the vertical central area B surrounded by the depression 7 is usually the part containing the opposite part (excretion point) of the excretion part, which is important for the body fluid excreted by the wearer who first received the sanitary napkin 1 and spread it. Part, at this time, the shape stability of this important part is high, and thereby, it is expected that various characteristics such as liquid absorbency (leakproofness), conformability, and wearing feeling will be further improved.

Hereinafter, the absorbent core 40 will be further described.

In the absorbent core 40, a plurality of fiber blocks 11 or fiber blocks 11 and water-absorbent fibers 12F are entangled with each other. In the absorbent core 40 of this embodiment, a plurality of fiber blocks 11 are combined with the constituent fibers (fibers 11F, 12F) in the absorbent core 40 to form 1 A continuum of fiber blocks. In addition, a plurality of fiber blocks 11 may be entangled with each other, and the fiber blocks 11 may be entangled with the water-absorbent fibers 12F to be combined. Furthermore, generally, a plurality of water-absorbing fibers 12F are also entangled with each other. At least a part of the plurality of fiber blocks 11 contained in the absorbent core 40 is entangled with other fiber blocks 11 or water-absorbent fibers 12F. In the absorbent core 40, there may be cases where a plurality of fiber blocks 11 contained therein are all intertwined to form a fiber block continuum, or there may be a plurality of fiber block continuums mixed with each other in a non-combined state. Condition. The entanglement of the fiber block 11, that is, the ease of entanglement with other fiber blocks 11 or water-absorbent fibers 12F, largely depends on the shape (number, size, distribution state of the following extended fiber portion 113 of the fiber block 11) Etc.), by appropriately controlling the shape of the extended fiber portion 113, the entanglement of the fiber block 11 can be improved.

The fiber block 11 is excellent in flexibility and the like. In this embodiment, regarding the absorbent core 40, as described above, the plurality of fiber blocks 11 contained therein are joined by mutual entanglement, and further, the fiber blocks 11 and the water-absorbent fibers 12F are also joined by mutual entanglement. The combination is excellent in shape retention, flexibility, cushioning, compression recovery, etc. When it is incorporated into the sanitary napkin 1, it is resistant to external forces from various directions (for example, the body pressure of the wearer of the absorbent article) It can be flexibly deformed and has good conformability so that the sanitary napkin 1 can be closely attached to the wearer's body.

FIG. 4 schematically shows the deformed state when the absorbent core 40 is compressed by the external force F. As shown in FIG. In the absorbent core 40 in which the fiber assembly, that is, the fiber block 11, and the non-fiber assembly, that are, water-absorbent fibers 12F are mixed, it is caused by the difference in rigidity between the two members 11, 12F, and the boundary BL between the two members 11, 12F (Figure The dotted line in 4) is particularly easy to bend, and the boundary BL functions as a bending portion when the absorbent core 40 is deformed. In this case, since the boundary BL as the bending portion usually exists throughout the entire area of the absorbent core 40, Therefore, the absorptive core 40 is responsive to various external forces and deforms flexibly, and when the external force is released, it can quickly return to the original state due to the compression recovery of the fiber block 11. Deformation of the absorbent core 40-Reply Special The properties can be expressed not only when the absorbent core 40 is compressed, but also when the absorbent core 40 is twisted. That is, the absorbent core 40 incorporated in the sanitary napkin 1 is arranged in a state of being sandwiched between the two thighs of the wearer when the sanitary napkin 1 is worn. Therefore, the absorbent core 4 is placed due to the wearer’s walking motion. The movement of the two thighs is twisted around the imaginary axis of rotation extending in the longitudinal direction X. However, since the absorbent core 40 has a high deformation-recovery characteristic, even in this case, it can also be targeted It promotes the twisting external force from the two thighs to easily deform and revert. Therefore, it is not easy to wrinkle, and the sanitary napkin 1 can be given a higher conformability to the wearer's body.

As described above, in the absorbent core 40, the fiber blocks 11 are entangled with each other or the fiber blocks 11 and the water-absorbent fibers 12F. At this time, the "entanglement" of the fiber blocks 11 referred to here includes the following forms A and B .

Form A: A form in which the fiber blocks 11 and the like are joined by the mutual entanglement of the constituent fibers 11F of the fiber blocks 11, instead of being joined by fusion.

Form B: In the natural state of the absorbent core 40 (the state where no external force is applied), the fiber blocks 11 are not bonded to each other, but in the state where external force is applied to the absorbent core 40, the fiber blocks 11 can be borrowed from each other A form in which the constituent fibers 11F are entangled with each other and joined. The “state in which an external force is applied to the absorbent core 40” as used herein refers to, for example, a state in which a deformation force is applied to the absorbent core 40 during wearing of an absorbent article to which the absorbent core 40 is applied.

In this way, in the absorbent core 40, the fiber block 11 may be combined with other fiber blocks 11 or water-absorbent fibers 12F by intertwining the fibers, that is, "interlacing" as in the form A, and may also be like the form B. It exists in a state where it can be entangled with other fiber blocks 11 or water-absorbent fibers 12F. The use of the entanglement of fibers is one of the important aspects to further effectively display the effect of the absorbent core 40. However, in terms of shape retention, it is more preferable that the absorbent core 40 has the "interlace" of the form A. Regardless of form A or B, use an absorbent core The entangled bonds of the constituent fibers in 40 are formed by entanglement of fibers without using components. Therefore, the bonding force itself is lower than that of the bonding using "fiber fusion" as described in Patent Document 2, for example, Conversely, the freedom of movement of the intertwined elements (fiber block 11, water-absorbent fiber 12F) is higher, and therefore, the individual elements can be moved within a range that can maintain their integrity as an aggregate including them. In this way, the absorbent core 40 is relatively loosely combined with the plurality of fiber blocks 11 or the fiber blocks 11 and the water-absorbing fibers 12F contained therein, and has a high level of shape retention that can be deformed and relieved when subjected to an external force. Take into account the shape retention and cushioning and compression and replies.

Furthermore, the combination of the fiber block 11 in the absorbent core 40 does not need to be "interlaced", and a part of the absorbent core 40 may also contain other bonding states other than the interlaced, for example, using an adhesive. Joining and so on.

However, for example, as a result of being integrated with other members of the absorbent article such as the recess 7 in the sanitary napkin 1, the self-absorbent core 40 excludes the "fusion via the fiber block 11" formed in the absorbent core 40 The remaining part obtained, that is, in the absorbent core 40 itself, it is preferable that the combination of the fiber blocks 11 or the combination of the fiber blocks 11 and the water-absorbent fibers 12F is formed only by "fiber entanglement".

From the viewpoint of more surely showing the effect of the above-mentioned absorbent core 40, the total number of form A, which is "fiber block 11 combined by entanglement", and form B, which is "fiber block 11 in a state that can be entangled" The total number of fiber blocks 11 in the absorbent core 40 is preferably more than half, more preferably more than 70%, more preferably more than 80%.

From the same point of view, the number of fiber blocks 11 having the "intersection" of form A is preferably more than 70% of the total number of fiber blocks 11 having joints with other fiber blocks 11 or water-absorbent fibers 12F. It is more than 80%.

As one of the main features of the absorbent core 40, the outer shape of the fiber block 11 can be cited. Fig. 5 shows a typical outer shape of two fiber blocks 11. The fiber block 11A shown in FIG. 5(a) has a quadrangular column shape, more specifically, a rectangular parallelepiped shape, and the fiber block 11B shown in FIG. 5(b) has a disc shape. The fiber blocks 11A and 11B have two opposing base planes 111 and a body plane 112 connecting the two base planes 111 in common. Both the basic surface 111 and the skeleton surface 112 are the parts that are considered to be substantially free of irregularities under the grade applied when evaluating the degree of surface irregularities in an article with such fibers as the main body.

The rectangular parallelepiped-shaped fiber block 11A of Fig. 5(a) has 6 flat surfaces. At this time, the two opposite surfaces with the largest area among the six surfaces are the basic surface 111, and the remaining 4 surfaces are respectively架面112。 Skeleton surface 112. The fundamental plane 111 and the skeleton plane 112 intersect each other, and more specifically, are orthogonal.

The disc-shaped fiber block 11B of Fig. 5(b) has two flat surfaces facing the circular shape in plan view, and a curved peripheral surface connecting the two flat surfaces. At this time, the two flat surfaces are respectively the basic surface 111 , The peripheral surface is the skeleton surface 112.

The fiber blocks 11A and 11B have a quadrangular shape in a plan view on the skeleton surface 112, and more specifically, they have a rectangular shape in common.

The plurality of fiber blocks 11 contained in the absorbent core 40 are respectively the fiber blocks 11A and 11B shown in FIG. The "fixed fiber assembly" is different from the non-woven fabric sheet or the fine fiber web described in Patent Documents 2 and 3, which are amorphous fiber assemblies. In other words, when any one fiber block 11 in the absorbent core 40 is seen through (for example, in the case of observation with an electron microscope), the see-through shape of the fiber block 11 is different according to its viewing angle, each The fiber block 11 has multiple see-through shapes. At this time, each of the plurality of fiber blocks 11 in the absorbent core 40 has There is a specific perspective shape having two opposing basic surfaces 111 and a skeleton surface 112 connecting the two basic surfaces 111 as one of its multiple perspective shapes. The plurality of non-woven fabric sheets or microfiber webs contained in the absorbent body described in Patent Documents 2 and 3 do not substantially have "planes" like the basic plane 111 or the skeleton plane 112, that is, have expanded parts, and the external shapes are different from each other. "Shaped."

In this way, if the plurality of fiber blocks 11 included in the absorbent core 40 is a "fixed fiber assembly" divided by the basic plane 111 and the skeleton plane 112, it is not the same as described in Patent Documents 2 and 3. Compared with the case of a fixed fiber assembly, the uniform dispersion of the fiber block 11 in the absorbent core 40 is improved. Therefore, the fiber assembly like the fiber block 11 is blended into the absorbent core 40 to stably appear Expected effects (improving effects of absorber’s flexibility, cushioning, compression recovery, etc.). Moreover, especially in the case of the rectangular parallelepiped-shaped fiber block 11 as shown in Figure 5(a), its outer surface includes 6 planes of 2 basic planes 111 and 4 skeleton planes 112, so it is similar to that shown in Fig. 5(b) Compared with the fiber block 11 with three outer surfaces in the disk shape shown in ), it has relatively more chances of contact with other fiber blocks 11 or water-absorbent fibers 12F. The intertwining property is improved, and the shape retention is also improved. Wait.

In the fiber block 11, the total area of the two basic surfaces 111 is greater than the total area of the skeleton surface 112. That is, in the cuboid-shaped fiber block 11A in Fig. 5(a), the sum of the areas of each of the two basic planes 111 is greater than the sum of the areas of each of the four skeleton planes 112, and in Fig. 5(b) In the disc-shaped fiber block 11B, the total area of each of the two basic surfaces 111 is greater than the area of the skeleton surface 112 forming the peripheral surface of the disc-shaped fiber block 11B. In any one of the fiber blocks 11A and 11B, the basic surface 111 is the surface with the largest area among the plurality of surfaces of the fiber blocks 11A and 11B.

The fiber block 11, which is formed by dividing the two basic planes 111 and the skeleton plane 112 intersecting the two basic planes 111, is realized by making the manufacturing method different from the prior art. As shown in Figure 6, the preferred method of manufacturing the fiber block 11 is to use a cutter or the like to cut The device cuts the raw fiber sheet 10bs (a sheet with the same composition as the fiber block 11 and larger in size than the fiber block 11) used as a raw material into a fixed shape. The plurality of fiber blocks 11 manufactured in this way have more consistent shapes and sizes than those using prior art manufacturers such as Patent Documents 2 and 3. Fig. 6 is a diagram illustrating a method of manufacturing the rectangular parallelepiped fiber block 11A of Fig. 5(a), and the broken line in Fig. 6 represents a cutting line. The absorbent core 40 is equipped with a plurality of fiber blocks 11 having uniform shapes and sizes obtained by cutting the fiber sheet into a fixed shape in this way. As described above, the raw fiber sheet 10bs is preferably a non-woven fabric.

As shown in FIG. 6, the rectangular parallelepiped fiber block 11A of FIG. 5(a) is formed by placing the raw fiber sheet 10bs in the first direction D1 and crossing the first direction D1 (more specifically, orthogonal) The second direction D2 is cut to a specific length and manufactured. The two directions D1 and D2 are respectively a specific direction in the plane direction of the sheet 10bs, and the sheet 10bs is cut along the thickness direction Z orthogonal to the plane direction. In this way, in a plurality of rectangular parallelepiped-shaped fiber blocks 11A obtained by cutting the raw fiber sheet 10bs into a so-called D shape, usually, the cut surface of the sheet 10bs is in contact with a cutting device such as a cutter when the sheet 10bs is cut. The surface is the skeleton surface 112, and the non-cutting surface, that is, the surface that is not in contact with the cutting device, is the basic surface 111. The basic surface 111 is the front and back surfaces (surfaces orthogonal to the thickness direction Z) of the sheet 10bs, and, as described above, is the surface with the largest area among the plural surfaces of the fiber block 11A.

Furthermore, the above description of the fiber block 11A is basically applicable to the disc-shaped fiber block 11B in FIG. 5(b). The essential difference between it and the fiber block 11A is only the cutting pattern of the raw fiber sheet 10bs. When the sheet 10bs is cut into a fixed shape to obtain the fiber block 11B, the sheet 10bs needs to be adapted to the top view shape of the fiber block 11B. Just cut it into a round shape.

In addition, the outer shape of the fiber block 11 is not limited to that shown in FIG. 5, and the basic surface 111 and the skeleton surface 112 may be flat surfaces that are not curved like the surfaces 111 and 112 of FIG. 5(a), or The frame surface 112 (the peripheral surface of the disc-shaped fiber block 11B) in FIG. 5(b) may also be a curved surface. In addition, the basic surface 111 and the skeleton surface 112 may have the same shape and size as each other. Specifically, for example, the outer shape of the fiber block 11A may be a cubic shape.

As described above, the two types of surfaces (basic surface 111 and skeleton surface 112) possessed by the fiber block 11 (11A, 11B) are classified as: The cutting formation of the raw fiber sheet 10bs of the cutting device; and the non-cutting surface (basic surface 111), which is the original surface of the sheet 10bs and does not contact the cutting device. In addition, due to the difference in the cut surface, the skeleton surface 112 which is the cut surface has a feature that the number of fiber ends per unit area is larger than that of the basic surface 111 which is the non-cut surface. The term "fiber end" as used herein means the end of the fiber 11F constituting the fiber block 11 in the longitudinal direction. Normally, fiber ends are also present on the non-cut surface, that is, the basic surface 111, but the skeleton surface 112 is a cut surface formed by cutting the raw fiber sheet 10bs, and therefore includes the constituent fibers 11F formed by the cutting. There are multiple fiber ends of the cut ends in the entire skeleton surface 112, that is, the number of fiber ends per unit area is more than the number per unit area of the basic plane 111.

The fiber ends existing on each surface of the fiber block 11 (the basic surface 111 and the skeleton surface 112) are useful for forming entanglements between the fiber block 11 and other fiber blocks 11 or water-absorbent fibers 12F contained in the absorbent core 40. In addition, generally, the greater the number of fiber ends per unit area, the more entanglement can be improved, and thus the shape retention properties of the absorbent core 40 can be improved. Moreover, as described above, the number of fiber ends per unit area in each surface of the fiber block 11 is not uniform. Regarding the number of fiber ends per unit area, the size relationship of "skeleton surface 112> basic surface 111" Therefore, the entanglement between the fiber block 11 and other fibers (the other fiber block 11 and the water-absorbent fiber 12F) differs according to the surface of the fiber block 11, and the skeleton surface 112 has higher entanglement than the basic plane 111. That is, the use of the combination of the entanglement with other fibers through the skeleton surface 112 and the through the base The bonding force of the original surface 111 is stronger than that of the fiber block 11. The basic surface 111 and the skeleton surface 112 can be used to make the bonding force with other fibers poor in one fiber block 11. Generally, the stronger the binding force, the more the freedom of movement of the combined fibers is restricted. As the absorbent core 40 as a whole, the strength (shape retention) increases, and conversely, the softness tends to decrease.

In this way, in the absorbent core 40, each of the plurality of fiber blocks 11 contained therein has two binding forces to other fibers (other fiber blocks 11, water-absorbent fibers 12F) around it, and they are intertwined, thereby absorbing The sexual core 40 has both moderate flexibility and strength (shape retention). In addition, when the absorbent core 40 with such excellent characteristics is used as an absorbent body of an absorbent article according to conventional practice, it can provide the wearer of the absorbent article with a comfortable wearing feeling and effectively prevent The external force such as the body pressure of the wearer during wearing destroys the defective condition of the absorbent core 40.

In particular, as described above, the total area of the two basic surfaces 111 of the fiber block 11 (11A, 11B) shown in FIG. 5 is greater than the total area of the skeleton surface 112. Therefore, it means that the number of fiber ends per unit area is relatively small, and therefore the total area of the basic plane 111, which has relatively low intertwinability with other fibers, is larger than that of the skeleton plane 112 having the opposite properties. Therefore, the fiber block 11 (11A, 11B) shown in FIG. 5 is easier to restrain the other fibers (other fiber block 11, water-absorbent fiber 12F) from the surrounding fibers than the fiber block with fiber ends uniformly existing on the entire surface. The entanglement, even if entangled with other fibers in the surrounding, is easy to entangle with relatively weak binding force, so it is not easy to become a larger agglomerate, and excellent flexibility can be imparted to the absorbent core 40.

On the other hand, as described above, the non-woven fabric sheet or the fine fiber web described in Patent Documents 2 and 3 is manufactured by cutting the raw fiber sheet into an indeterminate shape using a cutter like a milling cutter, and therefore does not become A sheet-like fiber block with a “face” like the basic plane 111 or the skeleton plane 112, and the cutting process is applied to the entire fiber block during its manufacture, so the fiber ends of the fibers will be randomly Formed in the whole fiber block, it is difficult to fully show the fiber The above-mentioned effect produced by the end.

From the viewpoint of obtaining the above-mentioned effects produced by the fiber end more reliably, the number per unit area of the fiber end of the basic plane 111 (non-cut surface) is N ₁ and the skeleton surface 112 (cut surface) The ratio of the number of fiber ends per unit area N ₂ is set before N ₁ <N _2. As N ₁ /N ₂ , it is preferably 0 or more, more preferably 0.05 or more, and preferably 0.90 Hereinafter, it is more preferably 0.60 or less. More specifically, N ₁ /N _{2 is} preferably 0 or more and 0.90 or less, and more preferably 0.05 or more and 0.60 or less.

_{The number N 1} per unit area of the fiber ends of the basic plane 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, and more It is preferably 6 pieces/mm ² or less.

_{The number N 2} per unit area of the fiber ends 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, and more Preferably, it is 40 pieces/mm ² or less.

The number per unit area of the fiber ends of the basic surface 111 and the skeleton surface 112 is measured by the following method.

<Method for measuring the number of fiber ends per unit area on each side of the fiber block>

For the member (fiber block) containing the fiber to be measured, a double-sided paper tape (NICETACK NW-15 manufactured by Miqibang Co., Ltd.) was used to attach the measurement piece to the sample stand. Then, platinum was applied to the measurement piece. The coating system used an ion sputtering device E-1030 (trade name) manufactured by Hitachi Naka Seiki Co., Ltd., and the sputtering time was set to 120 seconds. For each side of the test piece (fundamental plane and skeleton plane), use the JCM-6000 electron microscope manufactured by JEOL (stock) to observe at a magnification of 100 times. In the observation screen with the magnification of 100 times, in the measurement target surface (the fundamental surface or the skeleton Set a rectangular area of 1.2mm in length and 0.6mm in width at any position of the surface), and after adjusting the observation angle so that the area of the rectangular area occupies more than 90% of the area of the observation screen, measure the rectangular area contained The number of fiber ends. Among them, in the observation screen with a magnification of 100 times, when the measurement target surface of the fiber block is less than 1.2mm×0.6mm and the area of the above-mentioned rectangular area accounts for less than 90% of the entire observation screen, the observation magnification is greater than 100 times After that, the number of fiber ends included in the rectangular region in the measurement target surface was measured in the same manner as described above. Here, the "fiber end" that is the object of the number measurement is the end of the fiber in the length direction of the constituent fiber of the fiber block, even if the part of the constituent fiber other than the end in the length direction (the middle in the length direction) is from the measurement target surface Extend, the middle part in the longitudinal direction is not set as the target of the number measurement. Then, the number of fiber ends per unit area in the measurement target surface (fundamental surface or skeleton surface) of the fiber block is calculated by the following formula. For each of the 10 fiber blocks, measure the number of fiber ends per unit area in each of the basic plane and the skeleton plane according to the above sequence, and set the average of these plural measured values as the measurement target plane The number of fiber ends per unit area.

The number of fiber ends per unit area (number/mm ² ) = number of fiber ends contained in the rectangular area (1.2×0.6mm)/ The area of the rectangular area (0.72mm ² )

When the basic plane 111 of the fiber block 11 is shown in FIG. 5(a) and the fiber block 11A is rectangular in plan view, from the viewpoint of improving the uniform dispersion of the fiber block 11 in the absorbent body 4 The short side 111a of the rectangular shape is preferably equal to or shorter than the thickness of the absorbent core 40 containing the fiber block 11 (11A). The ratio of the length of the short side 111a to the thickness of the absorbent core 40 is preferably 0.03 or more, more preferably 0.08 or more, and more preferably 1 or less, and more preferably 0.5 or less in terms of the former/the latter.

The thickness of the absorbent core 40 is preferably 1 mm or more, more preferably 2 mm or more, and Furthermore, it is preferably 15 mm or less, and more preferably 10 mm or less. The thickness of the absorbent core 40 is measured by the following method.

<Measuring Method of Thickness of Absorber>

The object to be measured (absorbent core 40) is placed in a horizontal position without wrinkles or bending, and the thickness of the object to be measured under a load of ^{5 cN/cm 2 is measured.} Specifically, for the measurement of thickness, for example, a thickness meter PEACOCK DIAL UPRIGHT GAUGES R5-C (manufactured by OZAKI MFG. CO. LTD.) is used.

At this time, between the front end of the thickness gauge and the measured object to be cut, a circular or square flat plate (with a thickness of about 5 mm) adjusted in size so ^{that the load on the measured object becomes 5 cN/cm 2 is arranged.} Acrylic resin board), and measure the thickness. The thickness measurement is to measure 10 places, calculate the average value of them, and use it as the thickness of the object to be measured.

It is preferable to set the size etc. of each part of the fiber block 11 (11A, 11B) as shown below. The size of each part of the fiber block 11 can be measured based on the electron micrographs of the outer shape of the fiber block 11 described below during specific operations.

When the basic plane 111 is a rectangular shape in plan view as shown in FIG. 5(a), the length L1 of the short side 111a is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 10 mm or less , And more preferably 6 mm or less. The length L2 of the long side 111b of the rectangular basic surface 111 in plan view is preferably 0.3 mm or more, more preferably 2 mm or more, and more preferably 30 mm or less, and more preferably 15 mm or less.

Furthermore, as shown in FIG. 5, when the basic plane 111 is the plane with the largest area among the plural faces of the fiber block 11, the length L2 of the long side 111b and the maximum distance between the two ends of the fiber block 11 Consistent, the maximum distance between the two ends is the same as the top view circle in the disk-shaped fiber block 11B The basic surface 111 of the shape has the same diameter.

The ratio of the length L1 of the short side 111a to the length L2 of the long side 111b in terms of L1/L2 is preferably 0.003 or more, more preferably 0.025 or more, and more preferably 1 or less, and more preferably 0.5 or less. Furthermore, in the present invention, the top view shape of the basic plane 111 is not limited to the rectangular shape as shown in FIG. The ratio can also be 1 in terms of L1/L2.

The thickness T of the fiber block 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, and more preferably 6 mm or less .

In addition, the absorbent core 40 preferably has mechanical isotropy, so that all sides of the absorbent core 40 can easily obtain the effect due to the existence of the fiber block 11. Therefore, it is preferable that the fiber blocks 11 are distributed in a high density and uniformly over the entire absorbent core 40. From this point of view, it is preferable that the overlapping portions of the plurality of fiber blocks 11 exist in an arbitrary unit area of 10 mm square under projection observation in two directions orthogonal to each other of the absorbent core 40. The symbol 11Z in FIG. 3 and FIG. 4 represents the overlapping portion of the plurality of fiber blocks 11. As the "projection observation in two directions orthogonal to each other" referred to here, typically, a projection observation in the thickness direction of the absorbent core (absorbent body) (that is, for the absorbent core, from the Observation on the opposite or non-skin facing surface) and projection observation in the direction orthogonal to the thickness direction (that is, when the absorbent core is viewed from its side).

Fig. 7(a) shows an electron micrograph of an example of the fiber block of the present invention, and Fig. 7(b) shows a diagram schematically showing the fiber block 11 based on the electron micrograph. As shown in FIG. 7, the plurality of fiber blocks 11 included in the absorbent core 40 may include a main body 110 and fibers 11F that extend outward from the main body 110 and are configured to be opposite to the main body 110. Than fiber Those with lower dimensional density (the number of fibers per unit area is smaller) extending beyond the fiber portion 113. Furthermore, the absorbent core 40 may also include the fiber block 11 that does not have the extended fiber portion 113, that is, the fiber block 11 that only includes the main body portion 110. The extended fiber portion 113 is one of the fiber ends existing on each surface of the fiber block 11 (the basic surface 111, the skeleton surface 112), and is the fiber extending outward from each surface of the fiber block 11 in the fiber end portion. Ends.

The main body 110 is a part formed by dividing the above-mentioned two opposing basic surfaces 111 and a skeleton surface 112 connecting the two basic surfaces 111. The main body 110 constitutes the main body of the fiber block 11 and forms the part of the fixed outer shape of the fiber block 11. The fiber block 11 has relatively high flexibility, cushioning, compression recovery and other properties to a large extent. Depends on the body 110. On the other hand, the extended fiber portion 113 mainly contributes to the improvement of the entanglement between the plurality of fiber blocks 11 or the fiber block 11 and the water-absorbent fiber 12F contained in the absorbent core 40, and the protection of the absorbent core 40 The improvement of shape is directly related to it. In addition, it also affects the uniform dispersion of the absorbent core 40 of the fiber block 11, and can indirectly reinforce the effect produced by the main body 110.

The body portion 110 has a higher fiber density than the extended fiber portion 113, that is, the number of fibers per unit area is greater. Also, generally, the fiber density of the main body 110 itself is uniform. The ratio of the body portion 110 to the total mass of the fiber block 11 is usually at least 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 85% by mass or more. The main body portion 110 and the extended fiber portion 113 can be distinguished by the following specific operations of the outer shape.

The operation of specifying the outer shape of the main body 110 of the fiber block 11 contained in the absorbent core 40 can be performed by focusing on the difference in fiber density (the number of fibers per unit area) in the absorbent core 40 or The type of fiber, the difference in fiber diameter, etc., and the confirmation of the "boundary" between the main body 110 and other parts. The main body portion 110 has a higher fiber density than the extended fiber portion 113 existing around it, and, in general, is used as the structure of the main body portion 110 The synthetic fiber of the fiber and the water-absorbent fiber 12F (typically, cellulose fiber) are different in quality and/or size, so even if it is an absorbent core 40 in which a plurality of fiber blocks 11 and water-absorbent fibers 12F are mixed. The above-mentioned boundary can also be easily confirmed by focusing on the above-mentioned aspects. The boundary confirmed in this way is the periphery (side) of the basic surface 111 or the skeleton surface 112, and the basic surface 111 and the skeleton surface 112 are identified by the boundary confirmation operation, and then the main body 110 is identified. This boundary confirmation operation can be performed by observing the object (absorbent core 40) at a plurality of observation angles as necessary using an electron microscope. Especially when the fiber block 11 contained in the absorbent core 40 is the fiber block 11A, 11B shown in FIG. When the basic surface 111 becomes the surface with the largest area of the fiber block 11, the large-area basic surface 111 can be specified relatively easily, so that the external shape of the main body 110 can be specified smoothly.

As shown in FIG. 7(b), the extended fiber portion 113 includes at least one of the basic surface 111 and the skeleton surface 112 forming the outer surface of the main body portion 110, which is the constituent fiber 11F of the main body portion 110 extending outward. Fig. 7(b) is a plan view of the fiber block 11 from the basic plane 111 (the surface with the largest area among the plural faces of the fiber block 11). The fibers 11F extend more from the skeleton plane 112 intersecting the basic plane 111 These form the extended fiber part 113.

The shape of the extended fiber portion 113 is not particularly limited. The extended fiber portion 113 may include one fiber 11F, and may include a plurality of fibers 11F as in the extended fiber bundle portion 113S described below. In addition, the extended fiber portion 113 includes the longitudinal end portion of the fiber 11F extending from the main body portion 110, but there is a portion other than the longitudinal end portion of the fiber 11F that may include the fiber 11F in addition to the fiber end portion (length The middle part). That is, in the fiber block 11, both ends of the fiber 11F in the longitudinal direction are present in the main body 110, and the other part, that is, the middle part in the longitudinal direction, extends (protrudes) from the main body 110 to the outside in a ring shape. Situation, this In this case, the extended fiber portion 113 in this case is constituted by including the annular protrusion of the fiber 11F.

As described above, one of the main functions of the extended fiber portion 113 is to entangle the plurality of fiber blocks 11 contained in the absorbent core 40, or the fiber block 11 and the water-absorbent fiber 12F. Generally, if the extended length of the extended fiber portion 113 from the main body 110 becomes longer, or the thickness of the extended fiber portion 113 becomes thicker, or the number of extended fiber portions 113 in one fiber block 11 increases , The connection between the objects entangled through the extended fiber portion 113 becomes stronger and it is not easy to release the entanglement, so the specific effect of the present invention can be obtained more stably.

When the fiber block 11 is obtained by cutting the raw fiber sheet 10bs into a fixed shape as shown in FIG. Therefore, it does not exist at all on the non-cut surface, that is, the fundamental surface 111, or even if it exists, its number is less than that of the skeleton surface 112. In this way, the reason why the extended fiber portions 113 are concentrated on the skeleton surface 112 as the cut surface is that most of the extended fiber portions 113 are "fine hairs" generated by cutting the raw fiber sheet. That is, the skeleton surface 112 formed by the cutting of the raw fiber sheet 10bs is integrally rubbed by a cutting device such as a cutter when it is cut. Therefore, it is easy to form the fine hairs of the constituent fibers 11F including the sheet 10bs. So-called fluffing occurs. Although it also differs according to the type of the raw fiber sheet, if the interval between the cutting lines is shortened, or the cutting speed is slowed down, the extended fiber portion 113 can be easily formed, and its length can also be adjusted. On the other hand, the non-cut surface, that is, the basic surface 111 does not have such friction with the cutting device, so it is difficult to form fine hairs, that is, to extend the fiber portion 113.

The interval L1a (the interval in the first direction, refer to FIG. 6) and the interval L2a (the interval in the second direction, refer to FIG. 6) of the cutting line when the raw fiber sheet 10bs is cut promotes the formation of the above-mentioned extended fiber portion 113 From the viewpoints of the same, and the viewpoint of ensuring the size necessary for the fiber block 11 to exhibit a specific effect, etc., it is preferably 0.3 mm or more, more preferably 0.5 mm or more, and more preferably 30 mm or less. Preferably, it is 15 mm or less.

As shown in FIG. 7(b), the fiber block 11 has an extended fiber bundle portion 113S including a plurality of fibers 11F extending outward from the main body portion 110, more specifically from the skeleton surface 112, as a kind of the extended fiber portion 113 . At least one of the extended fiber portions 113 of the fiber block 11 may be the extended fiber bundle portion 113S. The extended fiber bundle portion 113S is formed by gathering a plurality of fibers 11F extending from the frame surface 112, and is characterized in that the extended length from the frame surface 112 is longer than that of the extended fiber portion 113. The extended fiber bundle portion 113S can also exist on the basic plane 111, but typically, as shown in Figure 7(b), it exists on the skeleton plane 112 and does not exist on the basic plane 111 at all, or even if it exists, its number is small于skeleton surface 112. The reason is the same as the reason why the extended fiber portion 113 mainly exists on the cut surface, that is, the skeleton surface 112, as described above.

The fiber block 11 has the extended fiber bundle portion 113S, which can also be called the long and thick large extended fiber portion 113, whereby the entanglement of the fiber block 11 or the fiber block 11 and the water-absorbent fiber 12F is further strengthened As a result, the specific effect of the present invention due to the existence of the fiber block 11 can be obtained more stably. The extended fiber bundle portion 113S can be easily formed by cutting the raw fiber sheet 10bs (refer to FIG. 6) under the above-mentioned easy-raising condition.

The extension length of the extended fiber bundle portion 113S from the main body 110, that is, the extension length from the skeleton surface 112 (cut surface) is preferably 0.05 mm or more, more preferably 0.15 mm or more, and preferably 7 mm or less , And more preferably 4 mm or less. The extended length of the extended fiber bundle portion 113S can be measured in the specific operation (boundary confirmation operation) of the outer shape of the fiber block 11 described above. Specifically, for example, using a microscope made by Keyence (50 magnification), a double-sided tape made by 3M (stock) is attached to the surface of a transparent sample table made of acrylic, and the fiber block 11 is placed on it and fixed , And then, according to the above-mentioned external shape specific operation, after the external shape of the fiber block 11 is specified, the length of the extended portion of the fiber 11F extending from the external shape is measured, and the measured extended portion is The length is defined as the extended length of the extended fiber bundle portion 113S.

The extended fiber bundle portion 113S is preferably such that a plurality of constituent fibers 11F are thermally fused to each other. The hot melt portion of the extended fiber bundle portion 113S is usually compared with the other parts (non-heat melt portion) of the extended fiber bundle portion 113S, and the two ends of the extended fiber bundle portion 113S in the direction orthogonal to the longitudinal direction The pitch length (when the cross section of the hot-melt part is circular, the diameter) is longer. By making the extended fiber bundle portion 113S have such a hot-melt portion, which can also be called a large-diameter portion, the strength of the extended fiber bundle portion 113S itself is improved, thereby, the fiber block entangled by the extended fiber bundle portion 113S The entanglement of 11 with each other or between the fiber block 11 and the water-absorbent fiber 12F is further strengthened. In addition, if the extended fiber bundle portion 113S has a hot melt portion, it has the following advantages: not only when the extended fiber bundle portion 113S is in a dry state, but also when it absorbs moisture and becomes a wet state, the extended fiber bundle portion 113S The strength and shape retention of the fiber bundle portion 113S itself are also improved. Moreover, with this advantage, when the absorbent core 40 is applied to an absorbent article, it goes without saying that the absorbent core 40 is in a dry state, even if it absorbs body fluids such as urine or menstrual blood excreted by the wearer. When it is in a wet state, the above-mentioned effect due to the existence of the fiber block 11 can also be stably obtained. Such an extended fiber bundle portion 113S having a hot-melt portion can be obtained by using the "having constituent fiber" in the manufacturing step of the fiber block 11 as shown in FIG. 6, that is, the cutting step of the raw fiber sheet 10bs of the fiber block 11 The fiber sheet of the hot melt part" is manufactured as the raw fiber sheet 10bs.

The constituent fibers 11F of the fiber block 11 include fibers having lower water absorption than the "weak water absorption" of the water-absorbent fibers 12F. The weakly absorbent fiber used as the fiber 11F is preferably a weakly absorbent synthetic fiber. The fiber 11F constituting the fiber block 11 is a weakly absorbent fiber, not only when the absorbent core 40 is in a dry state, but also when it absorbs water (body fluids such as urine or menstrual blood) and is in a wet state. The above-mentioned effects due to the existence of the fiber block 11 (improving effects of shape retention, flexibility, cushioning, compression recovery, and resistance to wrinkles, etc.) are stably obtained. The content of the weakly absorbent fibers constituting the fiber 11F in the fiber block 11 is relative to that of the fiber block 11 The total mass is preferably 90% by mass or more, and most preferably 100% by mass, that is, the fiber block 11 is formed only of weakly water-absorbent fibers. Especially when the weakly water-absorbent fiber constituting the fiber 11F is a non-water-absorbent fiber, the above-mentioned effect due to the existence of the fiber block 11 is further stably obtained.

In this specification, the term "water-absorbency" refers to, for example, that pulp is considered to be water-absorbent, and it can be easily understood by the industry. Similarly, thermoplastic fibers can also be easily understood as fibers that are weakly water-absorbent compared to pulp, and are non-water-absorbent fibers. On the other hand, the degree of water absorption of the fiber can be compared with the relative water absorption according to the value of the moisture content measured by the following method (the difference between water-absorbent fiber and fiber with weaker water absorption), and also Define a better range. The greater the value of the moisture content, the stronger the water absorption of the fiber. As the water-absorbent fiber of the present invention, the moisture content is preferably 6% or more, and more preferably 10% or more. On the other hand, the moisture content of the weakly absorbent fiber of the present invention is preferably less than 6%, and more preferably less than 4%. Furthermore, when the moisture content is less than 6%, the fiber can be judged as a non-absorbent fiber. That is, as the weakly water-absorbent fiber of the present invention, a non-water-absorbent fiber is preferable.

<Measurement method of moisture content>

The moisture content is calculated using the moisture content test method of JIS P8203. That is, after the fiber sample is left in a test chamber at a temperature of 40° C. and a relative humidity of 80% RH for 24 hours, the weight W (g) of the fiber sample before the absolute drying treatment is measured in the chamber. After that, it is allowed to stand in an electric dryer (for example, manufactured by ISUZU Manufacturing Co., Ltd.) at a temperature of 105±2° C. for 1 hour to perform absolute drying treatment of the fiber sample. After absolute drying treatment, in a standard laboratory with a temperature of 20±2°C and a relative humidity of 65±2%, the fiber sample is covered with Saran Wrap (registered trademark) manufactured by Asahi Kasei Co., Ltd. Silicone (for example, Toyota Chemical Co., Ltd.) is put into the glass desiccator (example For example, (manufactured by Tech jam), let it stand until the temperature of the fiber sample becomes 20±2°C. After that, the constant weight W'(g) of the fiber sample is weighed, and the moisture content of the fiber sample is obtained from the following formula.

Moisture rate (%)=(W-W'/W')×100

Also, similarly, from the viewpoint that the absorbent core 40 can exhibit excellent effects in terms of shape retention, flexibility, cushioning, compression recovery, and resistance to wrinkles in any of the dry state and the wet state. In other words, the fiber block 11 preferably has a three-dimensional structure in which a plurality of thermoplastic fibers are thermally fused to each other.

In addition, in order to obtain such a fiber block 11 in which a plurality of hot melt portions are three-dimensionally dispersed, the synthetic fiber used as the non-water-absorbent fiber as the constituent fiber 11F of the fiber block 11 is preferably a thermoplastic fiber. In addition, as described above, the extended fiber bundle portion 113S preferably has a hot-melt portion. In this case, the fiber 11F constituting the fiber block 11 is a thermoplastic fiber, and a preferable form of the extended fiber bundle portion 113S can also be obtained. .

In order to obtain a fiber block 11 in which a plurality of hot-melt portions are three-dimensionally dispersed, the raw fiber sheet 10bs (see FIG. 6) may be constructed in the same manner. In addition, as described above, such a plurality of hot-melt portions are three-dimensionally The dispersed raw fiber sheet 10bs can be manufactured by performing heat treatment such as hot air treatment on a fiber web or non-woven fabric mainly composed of thermoplastic fibers.

As a non-water-absorbent synthetic resin that is preferably used as a raw material of the fiber 11F of the fiber block 11, that is, a thermoplastic resin, for example, polyolefins such as polyethylene and polypropylene; and polyesters such as polyethylene terephthalate can be cited. ; Polyamides such as nylon 6, nylon 66; polyacrylic acid, polyalkyl methacrylate, polyvinyl chloride, polyvinylidene chloride, etc., which can be used alone or in combination of two or more. Furthermore, the fiber 11F may be a single fiber including one type of thermoplastic resin or a blended polymer formed by mixing two or more types of synthetic resins including thermoplastic resin, or may be a composite fiber. The composite fiber mentioned here refers to the use of spinning heads to combine different components A synthetic fiber (thermoplastic fiber) obtained by compounding two or more synthetic resins and spinning them simultaneously, and a plurality of components are connected to each other in a single fiber in a structure that is continuous in the length direction of the fiber. The form of the composite fiber includes a core-sheath type, a side-by-side type, etc., and is not particularly limited.

In addition, with regard to the fiber block 11, from the viewpoint of further improving the introduction of body fluids in the initial excretion, the contact angle with water measured by the following method is preferably less than 90 degrees, especially 70 degrees or less. As such fiber, it is obtained by conventionally treating the above-mentioned weakly water-absorbent fiber, preferably non-water-absorbent fiber, with a hydrophilizing agent. As the hydrophilizing agent, usual surfactants can be used.

<Measurement method of contact angle>

The fiber was taken out from the measurement object (absorbent core, fiber block), and the contact angle of water with respect to the fiber was measured. As the measuring device, the automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. was used. The contact angle is measured using deionized water. The amount of liquid ejected from an inkjet water droplet ejector (manufactured by Cluster Technology, a pulse jet CTC-25 with an aperture of 25 μm) was set to 20 picoliters, and the water droplets were dropped directly above the fiber. Record the dripping situation to a high-speed recording device connected to a horizontally set camera. From the point of view of subsequent image analysis, the video recording device is preferably a personal computer equipped with a high-speed capture device. In this measurement, the image was recorded every 17msec. In the recorded image, with the attached software FAMAS (the software version is set to 2.6.2, the analysis method is set to the droplet method, the analysis method is set to the θ/2 method, and the image processing algorithm is set to no reflection. The image processing image mode is set to the frame, the threshold level is set to 200, and no curvature correction is performed) Image analysis is performed on the initial image of the water droplet on the fiber, and the surface of the water droplet in contact with the air and the fiber are calculated. Angle and set it as the contact angle. The fiber taken out from the measurement object is cut to a fiber length of 1mm, and the fiber is placed on a contact angle meter. This station is maintained at a level. For each fiber, measure the contact angle of two different parts. Measure the contact angle of N=5 to 1 decimal point, and define the average of the measured values of 10 locations (rounded to the second decimal point) as the contact angle between the fiber and water. The measurement environment is set to room temperature 22±2°C and humidity 65±2%RH.

Furthermore, when the absorber (absorbent core) of the object to be measured is used as a constituent member of other articles such as absorbent articles, and the absorber is taken out for evaluation and measurement, the absorber is formed by adhesive, fusion, etc. In the case of fixing to other structural members, within the range that does not affect the contact angle of the fiber, use methods such as blowing cold spray to remove the adhesive force and then take out the fixed part. This sequence is common to all determinations in the specification of this case.

As the water-absorbent fiber 12F, the water-absorbent fiber previously used as the forming material of the absorbent body of this absorbent article can be used, for example, wood pulp such as conifer pulp or hardwood pulp, non-wood pulp such as cotton pulp or hemp pulp Natural fibers such as cationized pulp and mercerized pulp; modified pulps such as cationized pulp, mercerized pulp, etc.; one of them can be used alone or two or more of them can be used in combination. Among the water-absorbent fibers, cellulose-based water-absorbent fibers are particularly preferred.

In the absorbent core 40, the content ratio of the fiber block 11 to the water-absorbent fiber 12F is not particularly limited, and it is appropriate according to the types of the fiber block 11 (weakly absorbent synthetic fiber) 11F and the water-absorbent fiber 12F. Just adjust. For example, when the constituent fibers 11F of the fiber block 11 are non-absorbent fibers, that is, thermoplastic fibers, and the water-absorbent fibers 12F are cellulose-based water-absorbent fibers, from the viewpoint of achieving the specific effects of the present invention more reliably The content of the fiber block 11 and the water-absorbent fiber 12F is preferably 20/80~80/20, and more preferably 40/60~60/40 than the former (fiber block 11)/the latter (water-absorbent fiber 12F). .

The content of the fiber block 11 in the absorbent core 40 relative to the total mass of the absorbent core 40 in a dry state is preferably 20% by mass or more, and more preferably 40% by mass or more, and In addition, it is preferably 80% by mass or less, and more preferably 60% by mass or less.

The content of the absorbent fiber 12F in the absorbent core 40 relative to the total mass of the absorbent core 40 in the dry state is preferably 20% by mass or more, more preferably 40% by mass or more, and more preferably 80% % By mass or less, more preferably 60% by mass or less.

The fibrous mass 40 in the absorbent core 11 of the preferred basis weight of 32g / m ² or more, and further preferably 80g / m ² or more, and preferably of 640g / m ² or less, and further preferably from 480g / m ² or less.

The basis weight of the 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, and still more preferably 480 g/ ^{m 2} m ² or less.

The absorbent core 40 may contain other components other than the fiber block 11 and the water-absorbent fiber 12F, and as the other components, a water-absorbent polymer can be exemplified. As the water-absorbing polymer, particles in the form of particles are generally used, but those in the form of fibers may also be used. In the case of using a particulate superabsorbent polymer, its shape can be any of spherical, massive, bag-like or amorphous. The average particle size of the water-absorbing polymer is preferably 10 μm or more, more preferably 100 μm or more, and more preferably 1000 μm or less, and more preferably 800 μm or less. As the water-absorbing polymer, a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid can generally be used. As an example, polyacrylic acid and its salt, and polymethacrylic acid and its salt are mentioned.

The content of the water-absorbent polymer in the absorbent core 40 relative to the total mass of the absorbent core 40 in a dry state is preferably 5% by mass or more, more preferably 10% by mass or more, and more preferably 60 % By mass or less, more preferably 40% by mass or less.

The basis weight of the water-absorbing polymer in the absorbent core 40 is preferably 10 g/m ² or more, more preferably 30 g/m ² or more, and preferably 100 g/m ² or less, and more preferably 70 g/m 2 m ² or less.

The basis weight of the absorbent core 40 may be appropriately adjusted according to its use and the like. For example, when the purpose of the absorbent core 40 is the absorbent body of absorbent articles such as disposable diapers or menstrual sanitary napkins, the basis weight of the absorbent core 40 is preferably 100 g/m ² or more, and more preferably 200 g/m ² or more, preferably 800 g/m ² or less, and more preferably 600 g/m ² or less.

The absorbent core 40 having the above-mentioned constitution and the absorbent article like the sanitary napkin 1 provided with the absorbent core 40 are soft and have excellent cushioning properties, and are also excellent in compression recovery properties, and are deformed with good response to external forces , If the external force is released, it will quickly return to its original state. The characteristics of an absorbent article provided with such an absorbent body (absorbent core) can be evaluated using compression work (WC) and recovery work (WC') as a scale. The amount of compression work is a measure of the cushioning properties of absorbent articles, and it can be evaluated that the greater the WC value, the higher the cushioning properties. The amount of response work is a measure of the degree of response when the absorbent article is compressed and released from the compressed state. It can be evaluated that the greater the WC' value, the higher the compression response. In addition, considering the role of the absorbent core 40 for absorbing and retaining liquid, not only in a dry state, but also when absorbing body fluids and the like become wet, the absorbent article preferably has a larger WC value and WC' value. . In order to make the absorbent article have such characteristics in a wet state, as described above, an effective method is to use non-water-absorbent synthetic fibers such as thermoplastic fibers as the constituent fibers 11F of the fiber block 11.

The compression work (d-WC) in the dry state of the absorbent article is preferably 80mN. cm/cm ² or more, more preferably 90 mN. cm/cm ² or more, and preferably 150 mN. cm/cm ² or less, more preferably 110 mN. cm/cm ² or less.

The compressive work (w-WC) of the absorbent article in a wet state is preferably 70mN. cm/cm ² or more, more preferably 80 mN. cm/cm ² or more, and preferably 150 mN. cm/cm ² or less, more preferably 110 mN. cm/cm ² or less.

The response work (d-WC') of the absorbent article in a dry state is preferably 34mN. cm/cm ² or more, more preferably 44 mN. cm/cm ² or more, and preferably 150 mN. cm/cm ² or less, more preferably 60 mN. cm/cm ² or less.

The response work (w-WC') of the absorbent article in a wet state is preferably 15mN. cm/cm ² or more, more preferably 25 mN. cm/cm ² or more, and preferably 150 mN. cm/cm ² or less, more preferably 55 mN. cm/cm ² or less.

<Measurement method of compression work (WC) and response work (WC')>

It is generally known that the compression work (WC) and response work (WC') of absorbent articles can be expressed by the measured values of KES (KAWABATA EVALUATION SYSTEM) manufactured by Kato Technology Co., Ltd. (Reference: Standardization of Texture Evaluation And analysis (2nd edition), author Kawabata Yoshio, published on July 10, Showa 55). Specifically, the automatic compression test device KES-G5 manufactured by Jiaduo Technology Co., Ltd. can be used to measure the compression power and the response power. The measurement procedure is as follows.

Install the "absorbent article with absorber (menstrual sanitary napkin)" as the sample on the test bench of the compression test device. Next, the sample was compressed between steel plates having a circular flat surface with an area of 2 cm ^2. The compression speed is set to 0.02 cm/sec, and the maximum compression load is set to 490 mN/cm ² . The reply process is also measured at the same speed. The compression work (WC) and the response work (WC') are respectively expressed by the following formulas. Wherein, T _m, T _o represents a thickness of each thickness of 490mN / cm ² load, 4.9mN / cm ² load. In addition, P _a represents the load (mN/cm ² ) during the measurement (compression process), and P _b represents the load (mN/cm ² ) during the measurement (return process).

Furthermore, the measurement object of the above-mentioned measurement method, which is "absorbent article with absorbent body in a dry state", is prepared by placing the absorbent article in a dry state in an environment with a temperature of 23°C and a relative humidity of 50%RH for 24 hours. . In addition, the measurement object of the above-mentioned measurement method, namely "absorbent article with absorbent body in a wet state", is to place the absorbent article in a dry state horizontally so that the front sheet side (the side facing the skin) becomes the upper side. An oval injection port (50 mm long diameter and 23 mm short diameter) is placed on the front sheet, 3.0 g of defibrinated horse blood is injected from the injection port, and 3.0 g of defibrinated horse blood is injected after standing for 1 minute, and kept for 1 minute after injection Prepared in its state. In addition, the defibrinated horse blood that was injected into the measuring object was made by NIPPON BIOTEST (stock) and the viscosity was adjusted to 8cp at a liquid temperature of 25°C, and the viscosity was manufactured by Toki Industrial Co., Ltd. In the TVB-10M type viscometer, the viscosity of the rotor with the rotor name L/Adp (rotor code 19) is measured at a rotation speed of 12 rpm.

The absorbent core 40 can be manufactured in the same manner as an absorbent core (absorbent) containing such a fiber material. As described above, as shown in FIG. 6, the fiber block 11 can be used as a raw material fiber sheet (a sheet with the same composition as the fiber block 11 and larger than the fiber block 11) by using a cutting device such as a cutter. The plurality of fiber blocks 11 manufactured in this way are cut in two directions that cross each other (orthogonal) to be a "fixed fiber assembly" (for example, the main body 110 has a rectangular parallelepiped shape) with uniform shape and size. The absorbent core 40 including the fiber block 11 and the water-absorbent fiber 12F can be manufactured, for example, by using a known fiber stacking device equipped with a rotating drum in accordance with the usual practice. Typically, the fiber stacking device includes: a rotating drum with a concavity for accumulation formed on the outer peripheral surface; and a pipe with the raw material (fiber block 11, water-absorbent fiber 12F) of the absorbent core 40 inside being transported The flow path to the concavity for gathering; one side makes the rotating drum rotate around the circumference of the rotating drum When the shaft rotates, the raw material fibers conveyed in accordance with the air flow (vacuum air) generated in the flow path by suction from the inner side of the rotating drum are accumulated in the accumulation recess.

As mentioned above, the present invention has been described based on its embodiments, but the present invention is not limited to the above-mentioned embodiments and can be appropriately modified.

For example, in the absorbent core of the present invention, the fiber blocks may be unevenly dispersed throughout the absorbent core, or may be concentrated. As the form in which the fiber masses are concentrated, there can be exemplified an absorbent core having a laminated structure of a layer of the fiber mass constituting the main body and a layer of the water-absorbent fiber constituting the main body.

In addition, the absorbent core of the present invention may not contain all the fiber blocks (weakly absorbent synthetic fiber aggregates) that are shaped like fiber blocks 11, as long as they do not deviate from the gist of the present invention. In addition to the fixed fiber assembly, the range may further include a very small amount of indefinite fiber assembly.

The absorbent article of the present invention widely includes articles for absorbing body fluids (urine, soft stools, menstrual blood, sweat, etc.) discharged from the human body. In addition to the above-mentioned menstrual sanitary napkins, it also includes menstrual shorts and so-called fixed belts. Expandable disposable diapers, pants disposable diapers, incontinence pads, etc. Regarding the above-mentioned embodiments of the present invention, the following additional notes will be further disclosed.

<1> An absorbent article which has a longitudinal direction corresponding to the front and back directions of the wearer and a transverse direction orthogonal thereto, and is provided with an absorbent body and a front sheet disposed on the skin facing side of the absorbent body, The above-mentioned absorbent system is composed of a liquid-absorbing absorbent core and a core covering material covering the skin facing surface of the absorbent core. The fiber block of the weakly absorbent fiber of the sexual fiber; the liquid diffusion area of the above-mentioned absorbent core measured by the following method and the above-mentioned measured by the following method The ratio of the former/the latter of the liquid diffusion area of the core-coated sheet is 0.7 or more.

<Measurement method of liquid diffusion area>

On an inclined surface having an angle of 45° with respect to the horizontal plane, the measurement object is fixed so that the opposite side of the skin faces the inclined surface, and it takes 23 seconds to inject 1.5 g of defibrinated horse blood into the opposite surface of the measured object’s skin. After leaving for 3 minutes, perform the operation of injecting the same amount of defibrinated horse blood into the same injection site again, which takes the same amount of time, and repeat the injection and placing operations of the defibrinated horse blood 6 times, to obtain a total of 9g of defibrinated horse blood Inject into the measurement object, and after the injection operation is completed, measure the diffusion area of defibrillated horse blood in the opposite surface of the measurement object's skin, and use it as the liquid diffusion area of the measurement object.

<2> The absorbent article as described in the above <1>, wherein the core covering material is a porous sheet mainly composed of pulp.

<3> The absorbent article as described in the above <1> or <2>, in which the skin-facing surface of the absorbent body is partially formed with the core-clad material and the absorbent core facing the absorbent body. The sunken part that is integrally sunken on the opposite side of the skin.

<4> The absorbent article as described in the above <3>, wherein the absorbent article is divided in the longitudinal direction: a longitudinal central area, which includes an excretion part facing part facing the wearer's excretion part; and a front area, It is arranged on the ventral side of the wearer than the opposite part of the excretion part; and the rear area is arranged on the back side of the wearer than the opposite part of the excretion part; the recessed part surrounds the longitudinal central area It is formed in the horizontal center.

<5> The absorbent article as described in any one of the above <1> to <4>, wherein the outer shape of the fiber block is a rectangular parallelepiped shape or a disc shape.

<6> The absorbent article as described in any one of the above <1> to <5>, wherein the fiber block has a body portion with a relatively high fiber density, and is present in the body portion A plurality of the above-mentioned fiber blocks are intertwined with each other, and the above-mentioned fiber blocks and the above-mentioned water-absorbent fibers are intertwined with each other in the extended fiber part with a lower fiber density than the main body part.

<7> The absorbent article as described in the above <6>, wherein the main body has two opposing basic surfaces and a skeleton surface connecting the two basic surfaces, and the basic surface has a quadrangular shape in a plan view.

<8> The absorbent article as described in the above <7>, wherein the total area of the two basic surfaces is greater than the total area of the skeleton surface.

<9> The absorbent article according to the above <7> or <8>, wherein the fiber block has an extended fiber bundle portion, and the extended fiber bundle portion includes a plurality of fibers extending outward from the skeleton surface.

<10> The absorbent article as described in the above <9>, wherein the extended fiber bundle portion has a portion where a plurality of fibers are fused to each other by heat.

<11> The absorbent article as described in the above <9> or <10>, wherein the extended length of the extended fiber bundle portion from the main body, preferably the extended length from the frame surface is 0.05 mm or more And 7 mm or less, preferably 0.15 mm or more and 4 mm or less.

<12> The absorbent article as described in any one of the above <7> to <11>, wherein the basic surface has a rectangular shape in a plan view, and the short side of the rectangular shape is equal to or the same as the thickness of the absorbent body Shorter than.

<13> The absorbent article as described in the above <12>, wherein the ratio of the length of the shorter side of the basic surface to the thickness of the absorbent body is 0.03 or more and 1 or less, preferably 0.08 or more, and 0.5 or less.

<14> The absorbent article as described in the above <12> or <13>, wherein the length of the short side of the basic surface is 0.3mm or more and 10mm or less, preferably 0.5mm or more and 6mm the following.

<15> The absorbent article as described in any one of the above <12> to <14>, wherein the length of the long side of the basic surface is 0.3 mm or more and 30 mm or less, preferably 2 mm or more and 15 mm or less.

<16> The absorbent article as described in any one of the above <7> to <15>, wherein the number of fiber ends per unit area N ₁ existing on the above-mentioned basic surface and the number of fiber ends existing on the above-mentioned skeleton surface are The ratio N ₁ /N _{2 of the number N 2} per unit area of the part is 0 or more and 0.90 or less, preferably 0.05 or more and 0.60 or less.

<17> The absorbent article as described in any one of the above <7> to <16>, wherein the number per unit area of the fiber end portion existing on the above-mentioned basic surface is 0 pieces/mm ² or more and 8 pieces/ mm ² or less, preferably 3 pieces/mm ² or more and 6 pieces/mm ² or less.

<18> The absorbent article as described in any one of the above <7> to <17>, wherein the number per unit area of the fiber ends existing on the frame surface is 5 pieces/mm ² or more and 50 pieces/ mm ² or less, preferably 8 pieces/mm ² or more and 40 pieces/mm ² or less.

<19> The absorbent article as described in any one of the above <1> to <18>, wherein the fiber block has a three-dimensional structure in which a plurality of thermoplastic fibers are fused to each other.

<20> The absorbent article as described in any one of the above <1> to <19>, wherein the content ratio of the fiber block to the water-absorbent fiber is 20/80 to 80/20 in terms of the former/the latter.

<21> The absorbent article according to any one of the above <1> to <20>, wherein in the absorbent body, the fiber block is combined with other fiber blocks or the water-absorbent fiber by entanglement, It also exists in a state where it can be intertwined with other fiber blocks or the above-mentioned water-absorbent fibers.

<22> The absorbent article as described in any one of <1> to <21> above, which has More than 70%, preferably more than 80%, of the total number of the fiber blocks having a bonding portion with other fiber blocks or the water-absorbent fibers are formed by the entanglement of fibers.

<23> The absorbent article as described in any one of the above <1> to <22>, wherein the fiber block is derived from a non-woven fabric.

<24> The absorbent article as described in any one of <1> to <23> above, wherein the density of the core-coated material is 0.1 g/m ³ or less.

<25> The absorbent article as described in any one of the above <1> to <24>, wherein the density of the core covering material is 0.1 g/m ³ or less, preferably 0.08 g/m ³ or less, and, It is 0.02 g/m ³ or more, preferably 0.04 g/m ³ or more.

<26> The absorbent article as described in any one of the above <1> to <25>, wherein the basis weight of the core covering material is 50 g/m ² or less, preferably 30 g/m ² or less, and 5 g/m ² or more, preferably 10 g/m ² or more.

[Example]

Hereinafter, the present invention will be described in more detail with examples, but the present invention is not limited to these examples.

[Examples 1~2]

A menstrual sanitary napkin with the same composition as the sanitary napkin 1 shown in Fig. 1 is produced.

As the top sheet, a hot-air nonwoven fabric with a basis weight of 30 g/m ² was used, and as the back sheet, a film made of 37 g/m ² polyethylene resin was used. The absorbent system uses fiber blocks and water-absorbent fibers as the fiber material of the absorbent core, and then uses a separately prepared core-cladding material, and uses a well-known fiber stacking device, and is manufactured according to conventional practices. The fiber block is manufactured by cutting the raw fiber sheet into D-shapes according to Fig. 6.

As raw material fibers of the fiber sheet block, used to contain a polyethylene resin and a polyethylene thermoplastic fibers (fiber diameter 18 m) terephthalate resin constituting the fibers of basis weight of 21g / m ² of a hot-air nonwoven fabric (fibers constituting having The fiber sheet of the hot-melt part of each other). As the water-absorbent fiber, conifer sun-dried kraft pulp (NBKP) with a fiber diameter of 22 μm was used. The fiber block (formed synthetic fiber assembly) used for the absorbent body has a rectangular parallelepiped body as shown in Figure 5(a). The short side 111a of the basic plane 111 is 0.8mm, and the long side 111b is 3.9mm. The thickness T is 0.6 mm. In addition, the number of fiber ends per unit area in the basic plane 111 is 3.2 pieces/mm ² , and the number of fiber ends per unit area in the frame surface 112 is 19.2 pieces/mm ² . The basis weight of the absorber is 350g/m ² and the thickness is 5.7mm.

The details of the core-coated sheet (the above-mentioned porous sheet) used in Examples 1 and 2 are as follows. (Chip-coated material of Example 1)

The paper is made of conifer sun-dried kraft pulp (NBKP), with a basis weight of 13.5 g/m ² and a density of 0.092 g/cm ³ .

(The chip-coated material of Example 2)

The paper used mercerizing treatment with conifer sun-dried kraft pulp (NBKP) with a roundness of 0.80 and a basis weight of 16.0 g/m ² and a density of 0.069 g/cm ³ .

[Comparative Example 1]

A commercially available menstrual sanitary napkin (manufactured by Unicharm Co., Ltd., trade name "Tanom Pew slim 23cm") was directly used as Comparative Example 1. The absorbent system in the menstrual sanitary napkin of Comparative Example 1 contains synthetic fibers (weakly absorbent fibers) and cellulosic fibers (water absorbent fibers), so it does not contain fiber blocks.

[Comparative Example 2]

Except having changed the absorber into the following, the menstrual napkin was produced in the same manner as in Example 1, and it was taken as Comparative Example 2.

The absorbent body used in Comparative Example 2 used an indefinite non-woven fabric sheet as the fiber block in the absorbent core, and the absorbent core was coated with a core-clad material, and then subjected to hot air treatment to make the absorbent core contained The non-woven fabric sheets were thermally fused to each other, except for this, the same as the absorber used in Example 1. In the above-mentioned hot air treatment of the absorbent body, the mixed assembly (length 240mm×width 75mm) of the non-woven fabric sheet and the pulp fiber is placed in an electric dryer (for example, manufactured by ISUZU Manufacturing Co., Ltd.) at a temperature of 150°C. For 10 minutes, the non-woven fabric pieces are heat-melted to each other. The non-shaped non-woven fabric sheet used was manufactured by tearing off the same hot-air non-woven fabric used in Example 1 in any direction, and the distance between the two ends of the non-woven fabric sheet in the plan view was about 25 mm.

[Comparative Example 3]

Except changing the absorber to the following, the menstrual sanitary napkin was produced in the same manner as in Example 1, and it was taken as Comparative Example 3. Regarding the absorbent body used in Comparative Example 3, the absorbent core does not contain fiber blocks, but only contains the above-mentioned water-absorbent fibers. As the core-wrap material (the above-mentioned porous sheet), a conifer sun-dried kraft pulp (NBKP) ^{having a basis weight of 16.0 g/m 2} and a density of 0.102 g/cm ^{3 was used.}

[Performance Evaluation]

Regarding the menstrual sanitary napkins of the respective Examples and Comparative Examples, the liquid diffusion area of each of the absorbent core and the skin-side core covering material was measured by the above-mentioned method, and the liquid diffusion area ratio (absorbent core's Liquid diffusion area/liquid diffusion area of chip-coated material). Again, borrow The compression work (WC) and the recovery work (WC') were measured by the above-mentioned method, and the cushioning properties and the compression recovery performance were evaluated based on the measured values. The results are shown in Table 1 below.

As shown in Table 1, a plurality of fiber blocks in each embodiment are intertwined with each other, and the liquid diffusion area ratio (liquid diffusion area of the absorbent core/liquid diffusion area of the core-clad material) is 0.7 or more. Therefore, it is not satisfied Compared with the prior art, that is, Comparative Examples 1 to 3, the compression work (WC) and the recovery work (WC') values are larger in any of the dry state and the wet state. Therefore, in the two In the state, it has excellent cushioning properties and compression recovery properties. In addition, since the liquid diffusion area ratio of each example is in the above-mentioned specific range, the liquid permeability from the surface sheet to the absorbent core through the skin-side core covering material is excellent. Therefore, in each of the Examples, the body fluid is not likely to remain on the opposite side of the skin of the absorber after the body fluid is excreted.

[Industrial availability]

The absorbent article of the present invention has an absorbent body with high cushioning properties and liquid permeability. Therefore, according to the absorbent article of the present invention, the body fluid is not likely to remain in the body fluid after excretion The skin facing side of the absorber reduces the sticky or moist feeling of uncomfortable skin, and you can expect excellent wearing feeling and conformability.

1‧‧‧Sanitary napkins

2‧‧‧Front sheet

3‧‧‧Back sheet

4‧‧‧Absorber

6‧‧‧Side sheet

7‧‧‧Depression

11‧‧‧Fiber block

12F‧‧‧Water Absorbent Fiber

40‧‧‧Absorbent core

41‧‧‧Packing chip material

Y‧‧‧Horizontal

Claims (26)

An absorbent article which has a longitudinal direction corresponding to the front and back directions of the wearer and a transverse direction orthogonal thereto, and is provided with an absorbent body and a front sheet disposed on the skin facing side of the absorbent body, The above-mentioned absorbent system is composed of a liquid-absorbing absorbent core and a core covering material covering the skin facing surface of the absorbent core. The fiber block of the weak absorbent fiber of sex fiber; The ratio of the liquid diffusion area of the above-mentioned absorbent core measured by the following method to the liquid diffusion area of the above-mentioned core-cladding material measured by the following method is 0.7 or more, ＜Measuring method of liquid diffusion area＞ On an inclined surface having an angle of 45° with respect to the horizontal plane, the measurement object is fixed so that the opposite side of the skin faces the inclined surface, and it takes 23 seconds to inject 1.5 g of defibrinated horse blood into the opposite surface of the measured object’s skin. , After leaving for 3 minutes, perform the operation of injecting the same amount of defibrillated horse blood into the same injection site again, which takes the same amount of time, and repeat the injection and placing operations of the defibrillated horse blood for 6 times. The blood is injected into the measurement object, and after the injection operation is completed, the diffusion area of defibrillated horse blood in the skin facing surface of the measurement object is measured, and this is used as the liquid diffusion area of the measurement object. The absorbent article of claim 1, wherein the core-coated material is a porous sheet mainly composed of pulp. The absorbent article according to claim 1, wherein the skin-facing surface of the absorbent body is partially formed with a depression in which the core covering material and the absorbent core are integrally recessed toward the non-skin-facing surface side of the absorbent body Department. Such as the absorbent article of claim 3, wherein the above-mentioned absorbent article is divided longitudinally into: the longitudinal central area, which includes the excretion part opposed to the wearer’s excretion part; and the front area, which is arranged in comparison with the excretion part. The opposing part is closer to the wearer's ventral side; and the rear area is arranged on the dorsal side of the wearer than the excretory opposing part; The said recessed part is formed so that the horizontal center part of the said vertical center area may be enclosed. The absorbent article of claim 1, wherein the outer shape of the above-mentioned fiber block is a rectangular parallelepiped shape or a disc shape. The absorbent article of claim 1, wherein the fiber block has a main body portion with a relatively high fiber density and an extended fiber portion existing around the main body portion and having a lower fiber density than the main body portion, A plurality of the above-mentioned fiber blocks are entangled with each other, and the above-mentioned fiber blocks and the above-mentioned water-absorbent fibers are entangled with each other. An absorbent article according to claim 6, wherein the main body has two opposing basic surfaces and a skeleton surface connecting the two basic surfaces, and the basic surface has a quadrilateral shape in a plan view. Such as the absorbent article of claim 7, wherein the total area of the above two basic planes is greater than the total area of the above frame plane. The absorbent article according to claim 7, wherein the fiber block has an extended fiber bundle portion, and the extended fiber bundle portion includes a plurality of fibers extending outward from the frame surface. The absorbent article according to claim 9, wherein the extended fiber bundle portion has a portion formed by thermally fusing a plurality of fibers with each other. The absorbent article according to claim 9, wherein the extended length of the extended fiber bundle portion from the main body portion is 0.05 mm or more and 7 mm or less. The absorbent article according to claim 7, wherein the above-mentioned basic surface has a rectangular shape in a plan view, and the short sides of the rectangular shape are shorter than the thickness of the above-mentioned absorbent body. The absorbent article of claim 12, wherein the ratio of the length of the short side of the above-mentioned basic plane to the thickness of the above-mentioned absorbent body is calculated as 0.03 or more and 1 or less. Such as the absorbent article of claim 12, wherein the length of the short side of the above-mentioned basic plane is 0.3 mm or more and 10 mm or less. Such as the absorbent article of claim 12, wherein the length of the long side of the above-mentioned basic plane is 0.3 mm or more and 30 mm or less. Such as the absorbent article of claim 7, wherein the ratio _{of the number N 1} per unit area of the fiber end portion of the above-mentioned basic surface to the number _{per unit area N 2} of the fiber end portion of the above-mentioned skeleton surface _{is N 1} / N ₂ is 0 or more and 0.90 or less. Such as the absorbent article of claim 7, wherein the number per unit area of the fiber ends existing in the above-mentioned basic plane is 0 pieces/mm ² or more and 8 pieces/mm ² or less. The absorbent article according to claim 7, wherein the number per unit area of the fiber ends existing on the frame surface is 5 pieces/mm ² or more and 50 pieces/mm ² or less. The absorbent article of claim 1, wherein the fiber block has a three-dimensional structure formed by fusing a plurality of thermoplastic fibers with each other. The absorbent article of claim 1, wherein the content ratio of the fiber block to the water-absorbent fiber is 20/80 to 80/20. The absorbent article of claim 1, wherein in the absorbent body, the fiber block is not only combined with other fiber blocks or the above-mentioned water-absorbent fiber by entanglement, but also can be entangled with other fiber blocks or the above-mentioned water-absorbent fiber The state exists. The absorbent article of claim 1, wherein more than 70% of the total number of the fiber blocks having the bonding portion with the other fiber blocks or the water-absorbent fiber is formed by the entanglement of fibers. The absorbent article of claim 1, wherein the above-mentioned fiber block is derived from a non-woven fabric. The absorbent article of claim 1, wherein the density of the core-coated material is 0.1 g/m ³ or less. The absorbent article of claim 1, wherein the density of the core-coated material is 0.02 g/m ³ or more and 0.1 g/m ³ or less. The absorbent article of claim 1, wherein the basis weight of the core-coated material is 5 g/m ² or more and 50 g/m ² or less.

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