JP3244441U - Absorbent bodies and absorbent articles - Google Patents

Abstract

An object of the present invention is to provide an absorbent body that is resistant to twisting and can maintain absorbent performance even in a state where a gap is likely to occur between the absorbent article and the body, and an absorbent article equipped with the absorbent body. An absorbent core 4 of the present invention includes an absorbent core 40 containing a plurality of fiber masses including water absorbent fibers and synthetic fibers. The absorbent core 40 has a low fiber mass region R2 in which the basis weight of the fiber mass is 50 g/m2 or less, and a high fiber mass region R2 in which the basis weight of the fiber mass is 100 g/m2 or more. . The low fiber mass region R2 has a pair of notches 7, 7 extending inward in the width direction Y from both side edges along the longitudinal direction X, and is sandwiched between the pair of notches 7, 7. The cutout area R3 includes the entire area of the cutout area R3 defined as the area where the cutout area R3 is defined. [Selection diagram] Figure 1

Description

The present invention relates to an absorbent body and an absorbent article.

Absorbent articles such as sanitary napkins include an absorbent body that is the main liquid absorption site. Absorbent bodies are generally composed of water-absorbing materials such as water-absorbing fibers such as wood pulp and water-absorbing polymers, and are thicker and less rigid than other constituent members of the absorbent article. It tends to be higher. Therefore, the characteristics of the absorbent body have a considerable influence on the feeling of wearing the absorbent article. From the viewpoint of improving the wearing comfort, absorbent articles are known that include an absorbent body in which a cutout is provided in a portion.

For example, in Patent Document 1, in an absorbent body interposed between a topsheet and a backsheet, a notch is formed at the center of the rear end in the width direction, and further, a notch is formed in the center of the width direction of the rear end of the absorbent body interposed between the topsheet and the backsheet. discloses an absorbent article in which a sheet notch is formed along the notch.
Further, Patent Documents 2 and 3 disclose absorbent articles including an absorbent body in which a pair of bilaterally symmetrical notches are formed on both side edges along the longitudinal direction.

By the way, the present applicant has previously proposed an absorbent article including an absorbent body including a fiber agglomerate from the viewpoint of obtaining good wearing comfort and absorption performance (Patent Document 4). Such an absorbent body contains a fiber mass containing synthetic fibers and water-absorbing fibers, and the occupancy rate of the fiber mass (fiber mass occupancy) is made different for each predetermined region.

JP 2017-140422 Publication Japanese Patent Application Publication No. 2017-176743 JP2020-005845A Japanese Patent Application Publication No. 2020-096779

From the viewpoint of obtaining a good wearing feeling, it is desirable that the absorbent article be able to follow the movements of the wearer's body while being worn. However, when the wearer engages in strenuous exercise such as sports or wears the absorbent article for a long time, a gap forms between the absorbent article and the body, reducing the ability to follow the wearer's body. This may cause the absorbent article to become kinked. If the absorbent body absorbs body fluids or the like in addition to particularly strenuous exercise, not only will the above-mentioned kinks be more likely to occur, but the absorbent performance will decrease and there is a risk of leakage. Patent Documents 1 to 4 disclose techniques for improving wearing comfort, but even in conditions where a gap is likely to occur between the absorbent article and the body, such as during strenuous exercise, There was room for improvement in terms of being less likely to absorb moisture and maintaining absorption performance.

Therefore, an object of the present invention is to provide an absorbent body and an absorbent article equipped with the same, which is resistant to kinking and can maintain absorbent performance even when a gap is likely to occur between the absorbent article and the body. Concerning what to do.

The present invention relates to an absorbent body having a longitudinal direction and a width direction perpendicular to the longitudinal direction.
Preferably, the absorbent body includes an absorbent core containing a plurality of fiber aggregates including water-absorbing fibers and synthetic fibers.
The absorbent core has a low fiber mass region where the basis weight of the fiber mass is 50 g/m ² or less, and a high fiber mass region where the basis weight of the fiber mass is 100 g/m ² or more. It is preferable.
The low fiber mass region has a pair of notches extending inward in the width direction from each of both side edges along the longitudinal direction, and is defined as an area sandwiched between the pair of notches. It is preferable that the entire notch area is included.

The present invention also provides an absorbent article comprising the absorbent body, a top sheet disposed on the skin-facing side of the absorbent body, and a back sheet disposed on the non-skin-facing side of the absorbent body. Regarding.
The absorbent article has a central region including a region facing the wearer's excretory area, a front region located on the wearer's ventral side from the central region, and a wearer's dorsal side from the central region. It is preferred that the high fiber mass region is located within the central region.

According to the absorbent body and absorbent article of the present invention, even in a state where a gap is likely to occur between the absorbent article and the body, it is difficult to twist and can maintain absorbent performance.

FIG. 1 is a plan view schematically showing an embodiment of the absorbent body of the present invention. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a sectional view taken along the line III--III in FIG. FIG. 4 is a view corresponding to FIG. 1 showing another embodiment of the absorber according to the present invention. FIG. 5 is a plan view schematically showing the skin-facing side (top sheet side) of a sanitary napkin which is an embodiment of an absorbent article including the absorbent body shown in FIG. 1. FIGS. 6(a) and 6(b) are perspective views each showing an embodiment of the fiber mass according to the present invention. FIG. 7 is an explanatory diagram of a method for manufacturing the fiber mass shown in FIG. 6(a). FIG. 8 is a diagram corresponding to FIG. 2 showing an example of the distribution of fiber lumps in the thickness direction of the absorbent body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The absorbent body of the present invention will be described below based on preferred embodiments thereof with reference to the drawings. 1 to 3 show an embodiment of the absorbent body of the present invention.
As shown in FIG. 1, the absorbent body 4 of this embodiment has a long shape in one direction, and has a longitudinal direction X and a width direction Y orthogonal to the longitudinal direction. The absorbent body 4 is used by being indirectly applied to a person's skin by being incorporated into an absorbent article.

As shown in FIGS. 2 and 3, the absorbent body 4 in this embodiment includes a liquid-absorbent absorbent core 40 and a liquid-permeable core wrap sheet 41 that covers the outer surface of the absorbent core 40. I'm here. The absorbent core 40 constitutes the main body of the absorbent body 4. The absorbent core 40 and core wrap sheet 41 may be bonded together using an adhesive such as a hot melt adhesive.

In this embodiment, the core wrap sheet 41 is one continuous sheet. As shown in FIGS. 2 and 3, this core wrap sheet 41 covers the entire area of one side of the absorbent core 40, and covers both sides of the absorbent core 40 along the longitudinal direction X in the core wrap sheet 41. An extension extending outward in the width direction Y from the edge is rolled down below the absorbent core 40, thereby covering the other entire area of the absorbent core 40. Alternatively, the core wrap sheet 41 does not need to be one continuous sheet, and for example, one first core wrap sheet that covers one side of the absorbent core 40 and a separate sheet from this. The absorbent core 40 may be made of two sheets including one second core wrap sheet that covers the other surface of the absorbent core 40.

Absorbent core 40 contains a water absorbent material. The water-absorbing material includes water-absorbing fibers 12F and water-absorbing polymers 13. The absorbent core 40 of this embodiment contains water-absorbing fibers 12F and water-absorbing polymers 13 as water-absorbing materials.
As the water-absorbing fibers 12F, water-absorbing fibers conventionally used as materials for forming absorbers in this type of absorbent articles can be used. Examples of water-absorbing fibers include wood pulps such as softwood pulp and hardwood pulp, natural fibers such as non-wood pulps such as cotton pulp and hemp pulp; modified pulps such as cationized pulp and mercerized pulp; cupra, rayon, etc. These recycled fibers can be used alone or in combination of two or more. Considering that the main role of the water absorbent fibers 12F is to improve the liquid absorbency of the absorbent body 4, natural fibers and regenerated fibers (cellulose fibers) are preferable as the water absorbent fibers 12F.

In the absorbent core 40 of this embodiment, the water absorbent fibers 12F are intertwined with each other, but it is preferable that they are not integrated like the constituent fibers 11F of the fiber mass 11, but exist independently. The water absorbent fibers 12F mainly contribute to improving the liquid absorbency of the absorbent core 40, and also contribute to improving the shape retention of the absorbent core 40.

A plurality of water-absorbing polymers 13 are present in the absorbent core 40 as small pieces of water-absorbing polymers, and mainly contribute to improving the liquid absorbency within the absorbent core 40. The shape of the small pieces of water-absorbing polymer 13 is not particularly limited, and may be, for example, spherical, lump-like, bale-like, fibrous, or irregularly shaped. The average particle diameter of the water-absorbing polymer 13 is preferably 10 μm or more, more preferably 100 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less. As the water-absorbing polymer 13, a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid can generally be used. Examples include polyacrylic acid and its salts, polymethacrylic acid and its salts, and specifically, acrylic acid polymers such as Aqualic CA and Aqualic CAW (both manufactured by Nippon Shokubai Co., Ltd.). Partial sodium salts may be mentioned.

The absorbent core 40 contains a plurality of fiber masses 11 along with a water absorbent material. The constituent fibers 11F of the fiber mass 11 contain thermoplastic fibers. In this specification, the term "fiber mass" refers to a fiber aggregate made up of a plurality of fibers. The method for producing the fiber mass is not particularly limited, and for example, a fixed-shaped fiber aggregate such as a sheet piece obtained by cutting a synthetic fiber sheet (thermoplastic fiber sheet) having a certain size with a cutter or the like may be used. Alternatively, it may be an amorphous fiber aggregate manufactured by pulverizing, peeling, or tearing a nonwoven fabric mainly composed of thermoplastic fibers (synthetic fibers) into small pieces.
The absorbent body (absorbent core) of the present invention may be in a form that i) contains only fixed-shaped fiber aggregates as a fiber lump, or ii) contains only irregular-shaped fiber aggregates as a fiber lump. or iii) the fiber mass may be a mixture of regular-shaped fiber aggregates and irregular-shaped fiber aggregates. When the fiber mass 11 is a regular fiber aggregate, the orientation of the constituent fibers is constant, so the surface tends to be smooth. Since such fiber aggregates are unlikely to get entangled with each other, they have a high degree of freedom of movement and can contribute to the flexibility of the absorbent body 4. From this point of view, it is preferable that the fiber mass has the form i) above. In this embodiment, the fiber mass 11 is a regular fiber aggregate.

The fiber mass 11 is a fiber aggregate formed by integrating a plurality of fibers 11F into a mass, and is present in the absorbent core 40 while maintaining its shape. Due to the form of the fiber aggregate, the fiber mass 11 contributes to, for example, improving the flexibility, cushioning properties, compression recovery properties, and shape retention properties of the absorbent core 40.

The absorbent core 40 has a high fiber mass region R and a low fiber mass region R2 in which the basis weights of the fiber mass 11 are different from each other. In other words, the absorbent core 40 is divided into a high fiber mass region R and a low fiber mass region R2. The high fiber mass region R is a region where the basis weight of the fiber mass 11 is 100 g/m ² or more. The low fiber mass region R2 is a region in which the basis weight of the fiber mass 11 is 50 g/m ² or less.

The low fiber mass region R2 may contain the fiber mass 11 on the condition that the basis weight of the fiber mass 11 is lower than the high fiber mass region R. Moreover, the low fiber mass region R2 does not need to contain the fiber mass 11.

The high fiber mass region R of this embodiment has a higher basis weight of the fiber mass 11 and a higher basis weight of the material forming the absorbent core 40 than the low fiber mass region R2. Due to this, the thickness t (see FIG. 2) of the high fiber mass region R is larger than the thickness t1 (see FIG. 3) of the low fiber mass region R2.

As shown in FIG. 1, the low fiber mass regions R2 are located on both sides of the high fiber mass region R in the longitudinal direction X. That is, in the longitudinal direction X, the high fiber mass region R is sandwiched between the pair of low fiber mass regions R2, R2.

The low fiber mass region R2 has a pair of notches 7, 7 extending inward in the width direction Y from both side edges along the longitudinal direction X of the absorbent core 4, respectively. In this embodiment, each of the pair of low fiber mass regions R2, R2 has a pair of notches 7, 7. These pair of notches 7, 7 are located on the high fiber mass region R side in the longitudinal direction X (see FIG. 1).
The pair of notches 7, 7 of this embodiment bisect the absorber 4 in the width direction Y and are formed symmetrically with respect to a longitudinal center line CL extending in the longitudinal direction X.

The absorbent core 40 of this embodiment has two sets of a pair of notches 7, 7. The absorbent core 40 may have three or more pairs of notches 7, 7. For example, two pairs of notches 7, 7 may be provided on both sides of the high fiber mass region R in the longitudinal direction X, respectively. In this case, the absorbent core 40 has a total of four pairs of notches 7, 7. Alternatively, the absorbent core 40 may have only one pair of notches 7, 7.

In this specification, the region sandwiched between the pair of notches 7, 7 in the absorbent core 40 is defined as a "notch region R3." The notch region R3 is a narrow portion in which the widths of both side edges along the longitudinal direction X of the absorbent body 4 are narrowed, and is a constricted portion constricted inward in the width direction Y.
The low fiber mass region R2 includes the entire notch region R3. That is, the entire region of the notch region R3 overlaps with the low fiber mass region R2 in a plan view.

The absorbent body 4 of this embodiment is used by being incorporated into an absorbent article such as a napkin. When such an absorbent article is worn, the high fiber mass region R in which the basis weight of the fiber mass 11 is 100 g/m ² or more has excellent resilience against external forces such as the wearer's body pressure, and is gentle on the wearer's skin. Good fit. On the other hand, the low fiber mass region R2 in which the basis weight of the fiber mass 11 is 50 g/m ² or less is easily deformed by external force, and the low fiber mass region R2 is flexibly bent about the notch region R3 as a rotation axis. It has excellent conformability to the wearer's body. In this way, the absorbent core 4 (absorbent core 40) having two regions R and R2 with different basis weights of the fiber mass 11 is suitable for use when the wearer is doing strenuous exercise or when worn for a long time. Even when the absorbent body 4 is in contact with the skin, the low fiber mass region R2 can be made to closely follow the movement of the skin while the high fiber mass region R is in close contact with the skin. It is difficult for a gap to occur between the absorbent articles (hereinafter also referred to as "gap suppression effect"), and it is possible to effectively suppress twisting of the absorbent article due to body movements. Moreover, since the basis weight of the fiber mass 11 is high and body fluids are preferentially absorbed in the high fiber mass region R that is in close contact with the skin, the absorption performance is unlikely to deteriorate even after absorbing body fluids. This provides an excellent effect of suppressing leakage even when worn for long periods of time. Therefore, the absorbent body 4 of this embodiment is resistant to kinking and has excellent absorbent performance even in conditions where a gap is likely to occur between the absorbent article and the body, such as during strenuous exercise or when worn for a long period of time. can be maintained.

The absorbent core 40 of this embodiment has low fiber mass regions R2, R2 on both sides of the high fiber mass region R in the longitudinal direction X, and is located in both low fiber mass regions R2, R2, respectively. The high fiber mass region R is arranged between the cutout regions R3, R3 (see FIG. 1). With such a configuration, deformation using the high fiber mass region R as a fulcrum and both notch regions R3, R3 as rotation axes is facilitated, thereby further improving the adhesion of the high fiber mass region R to the skin. At the same time, both low fiber mass regions R2, R2 can be bent more flexibly. As a result, even if the absorbent article is worn for a long time, the effect of suppressing gaps is maintained, so that deterioration in absorbent performance is suppressed. In addition, the ability to follow the body remains high.

From the viewpoint of more reliably achieving the above effect, when the entire length of the absorbent body 4 in the longitudinal direction It is preferable that the lump region R is located in the central region M of the three regions. In this case, the high fiber mass region R may extend into two regions: a central region M and one or the other region S adjacent thereto.

Each of the pair of notches 7, 7 has a convex shape toward the inside in the width direction Y, and has an inner end P located at the innermost side in the width direction Y. In FIG. 1, the position of the inner end P in the width direction Y is indicated by a dotted line e1.
One side edge along the longitudinal direction X of the absorbent core 4 has notches 7a and 7b on both sides of the high fiber mass region R in the longitudinal direction X, and these notches 7a and 7b are The positions of the inner ends P in the width direction Y match. Similarly, on the other side edge of the absorbent body 4 along the longitudinal direction ing.
Moreover, in the absorber 4 of this embodiment, the notch regions R3, R3 located on both sides of the high fiber mass region R in the longitudinal direction X are the same shape and the same size in plan view. That is, a pair of notches 7, 7 located on both sides of the high-fiber mass region R in the longitudinal direction . The inter-notch area imaginary line e2 is an imaginary line that bisects the distance between the notch areas R3, R3 in the longitudinal direction X and extends in the width direction Y.

The cutout region R3 serves as a pivot axis when the low fiber mass region R2 bends as described above. From the viewpoint of further increasing the flexibility in the notch region R3 and further improving the ability to follow the body, the dimensions of the notch portion 7 are preferably within the following ranges.
The notch length d (see FIG. 1) of the notch portion 7 is preferably 5% or more and 40% or less, more preferably 7% or more and 35% or less, with respect to the full width W of the absorbent body 4 (see FIG. 1). It is.
The total width W of the absorbent body 4 is the maximum length of the absorbent body 4 in the width direction Y. The notch length d of the notch portion 7 is the length in the width direction Y between the side edge along the longitudinal direction X of the absorber 4 and the inner end P.
The notch length d (see FIG. 1) of the notch portion 7 is preferably 3 mm or more and 25 mm or less, more preferably 10 mm or more and 15 mm or less.

From the same viewpoint as above, the distance (not shown) between the high fiber mass region R and the notch 7 in the longitudinal direction X is preferably 2 mm or more and 20 mm or less, more preferably 5 mm or more and 18 mm or less.

The length L3 (see FIG. 1) of the cutout portion 7 in the longitudinal direction More preferably, it is 7% or more and 27% or less. The length L3 of the notch 7 in the longitudinal direction X is the maximum length of the notch 7 in the same direction.
The length L3 (see FIG. 1) of the notch 7 in the longitudinal direction X is preferably 3 mm or more and 25 mm or less, more preferably 5 mm or more and 20 mm or less.

From the viewpoint of making it easier to follow the body, the minimum length W1 (see FIG. 1) of the notch region R3 in the width direction Y is preferably 30 mm or more, more preferably 40 mm or more, and preferably 100 mm or less. , more preferably 90 mm or less, more preferably 50 mm or more and 70 mm or less, and preferably 50 mm or more and 65 mm or less.

It is preferable that the core wrap sheet 41 is notched along the notch portion 7 in order to more easily bend the low fiber mass region R2 in the notch region R3. Such a configuration can be obtained by covering the absorbent core 40 with a core wrap sheet 41, and then making cuts on both side edges of the absorbent core 40 together with the core wrap sheet 41 to form the cutout portions 7. .

Hereinafter, the ratio of the mass of the fiber mass 11 to the total mass of the fiber mass 11 and the water-absorbing fibers 12F in each region of the absorbent body 4 [mass of the fiber mass 11/(mass of the fiber mass 11 + mass of the water-absorbing fiber 12F)] ] is also called "fiber lump content".
From the viewpoint of further improving absorption performance, the fiber lump content in the high fiber lump region R is preferably 5% by mass or more, more preferably 20% by mass or more, and preferably 95% by mass or less, more preferably 80% by mass. It is as follows.
From the viewpoint of further improving deformability, the fiber lump content in the low fiber lump region R2 is preferably less than 20% by mass, more preferably 1% by mass or less.

From the viewpoint of further improving the gap suppression effect, the basis weight of the fiber mass 11 in the high fiber mass region R is preferably 105 g/m ² or more, more preferably 150 g/m ² or more, and preferably 640 g/m ² It is more preferably 480 g/m ² or less.
From the viewpoint of further improving conformability to the body, the basis weight of the fiber mass 11 in the low fiber mass region R2 is preferably 10 g/m ² or less, more preferably 5 g/m ² or less, and 0 g/m ^{2 or less} . There may be.

In the high fiber mass region R of this embodiment, one of the two surfaces having the largest area in the absorbent body 4 has a higher fiber mass content than the other surface. With such a configuration, it is possible to further improve the gap suppression effect, further increase the adhesion to the body, and more effectively suppress the decrease in absorption performance. The "two surfaces" are the surfaces with the largest area in the absorbent body 4, and are usually the liquid-receiving surface that first comes into contact with the liquid to be absorbed, or the surface opposite to the liquid-receiving surface; 4 becomes a skin-facing surface or a non-skin-facing surface when incorporated into an absorbent article. In such a state, in the absorbent body 4, from the viewpoint of obtaining good absorption performance, it is preferable that the surface side having a relatively higher fiber lump content among the two surfaces is the non-skin-facing surface side.

To explain the above configuration more specifically, the high fiber mass region R is divided into two equal parts in the thickness direction Z, and is divided into a region on one surface side and a region on the other side of the two surfaces where the area in the absorbent body 4 is maximum. When divided into two surface-side regions, it is preferable that more fiber lumps 11 exist in one surface-side region than in the other surface-side region (see FIG. 2). That is, in the high fiber mass region R, the fiber mass 11 is preferably unevenly distributed on one of the two surfaces in the thickness direction Z of the absorbent core 4.

From the viewpoint of more reliably achieving the above effects, the high fiber lump region R is defined such that the fiber lump content in the region on the one surface side where the fiber lumps 11 are unevenly distributed is lower than the fiber lump content in the region on the other surface side. The ratio is preferably 2 times or more, more preferably 10 times or more. In addition, the most preferable form is that the fiber mass exists only in the region on one side and the fiber mass does not exist in the region on the other surface side. In this case, the ratio of the fiber lump content in the area on one side and the fiber lump content in the area on the other side is numerically infinite.

From the viewpoint of ensuring absorption performance more reliably, the absorbent body 4 of this embodiment is attached to an absorbent article such as a napkin 1 with the one surface side where the fiber lumps 11 are unevenly distributed facing the non-skin facing side. Preferably, it is incorporated. The structure of each part of such an absorbent article will be described later.

In the absorbent core 40 of this embodiment, the adjacent fiber masses 11 are intertwined with each other, and the adjacent fiber masses 11 and the water-absorbing fibers 12F are intertwined with each other. The plurality of fiber masses 11 in the high fiber mass region R may be combined by entanglement with constituent fibers (fibers 11F, 12F) in the absorbent core 40 to form one continuous fiber mass. In this way, at least a portion of the plurality of fiber masses 11 are intertwined with other fiber masses 11 or water-absorbing fibers 12F.
In the absorbent core 40, all of the plurality of fiber masses 11 contained therein may be intertwined with each other to form one continuous fiber mass, and the plurality of continuous fiber masses may be in a state in which the plurality of continuous fiber masses are not bonded to each other. may be mixed.

The distribution of the water absorbent polymer 13 in the absorbent core 40 is not particularly limited, and may be uniformly distributed throughout the absorbent core 40 or unevenly distributed in a part of the absorbent core 40. From the viewpoint of further improving absorption performance, it is preferable that the water-absorbing polymer 13 exists in the high fiber mass region R. Moreover, the water-absorbing polymer 13 may be present in the low fiber mass region R2.

From the viewpoint of further improving the gap suppression effect, the length L1 (see FIG. 1) of the high fiber mass region R in the longitudinal direction % or more and 60% or less, more preferably 20% or more and 50% or less.
From the same viewpoint as above, the length L1 (see FIG. 1) of the high fiber mass region R in the longitudinal direction X is preferably 30 mm or more and 100 mm or less, more preferably 40 mm or more and 90 mm or less.

From the viewpoint of further improving the fit to the skin, the area of the high fiber mass region R is preferably 10% or more and 70% or less, more preferably 20% or more and 50% or less of the area of the absorbent body 4.
From the same viewpoint as above, the area of the low fiber mass region R2 is preferably 30% or more and 90% or less, more preferably 50% or more and 80% or less of the area of the absorbent core 4.
When there is a plurality of low fiber lump regions R2 as in this embodiment, the area of the low fiber lump regions R2 means the area of one low fiber lump region R2.

From the viewpoint of achieving both adhesion to the skin and trackability, the thicknesses of the high fiber mass region R and the low fiber mass region R2 are preferably within the following ranges.
The thickness t (see FIG. 2) of the high fiber mass region R is preferably 103% or more and 400% or less, more preferably 110% or more and 250% or less of the thickness t1 (see FIG. 3) of the low fiber mass region R2.
The thickness t (see FIG. 2) of the high fiber mass region R is preferably 2 mm or more and 20 mm or less, more preferably 3 mm or more and 9 mm or less.
The thickness t1 (see FIG. 3) of the low fiber mass region R2 is preferably 1 mm or more and 8 mm or less, more preferably 2 mm or more and 7 mm or less.
The thickness of each part of the absorbent body 4, such as the high fiber mass region R, is measured by the following method.

<How to measure thickness>
The absorbent body is placed in a horizontal position without wrinkles or bends, and a measurement target area (for example, the skin-facing surface side or the non-skin-facing surface side of the absorbent body) is cut out from the absorbent body and used as a measurement sample. Then, the thickness of the measurement sample under a load of 5 cN/cm ² is measured. Specifically, to measure the thickness, for example, a thickness meter PEACOCK DIAL UPRIGHT GAUGES R5-C (manufactured by OZAKI MFG.CO.LTD.) is used. At this time, a circular or square plate (acrylic plate approximately 5 mm thick) in plan view, whose size is adjusted so that the load is 5 cN/ ^cm2 , is placed between the tip of the thickness gauge and the measurement sample. and measure the thickness. In the thickness measurement, arbitrary 10 locations on the measurement sample are measured, and the average value of the thicknesses at these 10 locations is calculated and used as the thickness of the measurement sample.

FIG. 4 shows another embodiment of the absorbent body according to the present invention. Regarding the embodiment shown in FIG. 4, components different from those of the embodiment described above will be mainly explained, and similar components will be given the same reference numerals and explanations will be omitted. The description of the above-mentioned embodiment applies as appropriate to the constituent parts that are not particularly described.

In the absorbent body 4a of this embodiment, the pair of notches 7, 7 have a convex shape inward in the width direction Y, and have an inner end P located at the innermost side in the width direction Y. have. The inner ends P of the pair of notches 7, 7 are biased towards the high fiber mass region R in the longitudinal direction X. That is, when assuming that the length of the notch 7 in the longitudinal direction is also located on the high fiber mass region R side (see FIG. 4). With this configuration, the rotation axis in the notch region R3 can be formed on the side of the high fiber mass region R, and the low fiber mass region R2 can be deformed while being followed by the body.

From the viewpoint of more reliably achieving the above effect, the distance L5 (see FIG. 4) between the inner end P of the pair of notches 7, 7 in the longitudinal direction X and the notch center line f is as follows: Preferably it is 0.5 mm or more and 10 mm or less, more preferably 2 mm or more and 8 mm or less.

In this embodiment, the pair of notches 7c, 7c located on one side of the high fiber mass region R in the longitudinal direction X has a triangular outline with the inner end P as the apex. Moreover, the outline of the pair of notches 7d, 7d located on the other side of the high fiber mass region R in the longitudinal direction X is a convex curve with the inner end P as the apex. That is, the pair of notches 7, 7 located on both sides of the high fiber mass region R in the longitudinal direction X are formed asymmetrically with respect to the virtual line e2 between the notch regions (see FIG. 4). . As a result, the cutout regions R3, R3 located on both sides of the high fiber mass region R in the longitudinal direction X have different shapes in plan view.

Next, an absorbent article equipped with an absorbent body according to the present invention will be described, taking as an example an absorbent article equipped with an absorbent body 4 shown in FIGS. 1 to 3. FIG. 5 shows a sanitary napkin 1 (hereinafter also simply referred to as "napkin 1"), which is an embodiment of the absorbent article.
As shown in FIG. 5, the napkin 1 has a vertical direction X1 that corresponds to the front-back direction of the wearer and extends from the ventral side of the wearer through the groin area to the back side, and a horizontal direction Y1 that is perpendicular to this. are doing. In the longitudinal direction The front region A is located on the ventral side of the wearer, and the rear region C is located on the back side of the central region B in the longitudinal direction X1 (on the back side of the wearer). It is classified.

The napkin 1 shown in FIG. A back sheet 3 disposed on the opposing surface side. The absorbent body 4 is assembled into the napkin 1 with its longitudinal direction X aligned with the longitudinal direction X1.
The absorbent body 4 extends approximately the entire length of the napkin 1 in the longitudinal direction X1. In other words, the absorbent core 4 extends from the front region A to the rear region C via the central region B.

In this specification, the "skin-facing surface" refers to the surface of the absorbent article or its constituent members (for example, the absorbent core 4) that faces the wearer's skin when the absorbent article is worn, and the "non-skin-facing surface" ” is the surface of the absorbent article or its constituent members that faces away from the skin side when the absorbent article is worn. That is, the skin-facing surface is a surface relatively close to the wearer's skin, and the non-skin-facing surface is a surface relatively far from the wearer's skin. "When worn" and "wearing state" mean a state in which the absorbent article is worn in a normal proper wearing position, that is, the absorbent article is maintained in a proper wearing position.

As shown in FIG. 5, the napkin 1 includes an absorbent main body 5 that is long in the vertical direction X1, and extends outward in the horizontal direction Y1 from both sides along the vertical direction It has a pair of wing parts 5W, 5W that extend out. The absorbent main body 5 is the main part of the napkin 1 and includes the above-mentioned top sheet 2, back sheet 3, and absorbent core 4.

When the absorbent article has the wing portions 5W as in this embodiment, the central region B is a region having the wing portions 5W in the longitudinal direction X1. Specifically, an imaginary straight line extends in the horizontal direction Y1 through the front roots of the pair of wing parts 5W, 5W in the longitudinal direction X1, and a virtual straight line extends through the rear roots of each of the pair of wing parts 5W, 5W. The area sandwiched between the virtual straight line extending in the horizontal direction Y1 is the central area B.
In the napkin 1 of this embodiment, the pair of wing parts 5W, 5W are formed symmetrically with respect to a vertical center line that divides the napkin 1 into two in the horizontal direction Y1 and extends in the vertical direction X1, and one of the wing parts The front root of the wing portion 5W and that of the other wing portion 5W are located at the same position in the longitudinal direction X1.

When the absorbent article does not have wing portions (for example, a disposable diaper), the central region B corresponds to, for example, the region located in the center when the absorbent article is divided into thirds in the longitudinal direction X1.

The topsheet 2 of this embodiment covers the entire skin-facing surface of the absorbent core 4. On the other hand, the back sheet 3 covers the entire area of the non-skin facing surface of the absorbent body 4, further extends outward in the horizontal direction Y1 from both side edges of the absorbent body 4 along the longitudinal direction X1, and together with the side sheet 6 described later. A side flap portion SF is formed. The side flap portion SF is a portion made of a sheet member that extends outward in the horizontal direction Y1 from both side edges of the absorbent body 4 along the vertical direction X1. The sheet member constituting the side flap portion SF extends from the front region A through the center region B to the rear region C, and extends outward in the lateral direction Y1 from each side edge of the absorbent body 4. The parts are joined to each other by known joining means such as adhesive, heat sealing, ultrasonic sealing, etc. The side flap portion SF of the present embodiment includes a back sheet 3 and a side sheet 6 that extend outward in the lateral direction Y1 from both side edges of the absorbent core 4.

As the top sheet 2 and the back sheet 3, various materials conventionally used in absorbent articles such as sanitary napkins can be used without particular limitation. For example, as the top sheet 2, a liquid-permeable sheet such as a nonwoven fabric with a single layer or multilayer structure or a perforated film can be used. As the back sheet 3, a liquid-impermeable sheet such as a moisture-permeable resin film can be used.

As shown in FIG. 5, the side flap portion SF of this embodiment largely protrudes outward in the horizontal direction Y1 in the central region B, thereby extending both the left and right sides of the absorbent main body 5 in the vertical direction X1. , a pair of wing parts 5W, 5W are extended. The wing portion 5W has a substantially trapezoidal shape in which the lower base (the side longer than the upper base) is located on the side of the absorbent main body 5 in a plan view as shown in FIG. A wing adhesive portion (not shown) for fixing the wing portion 5W to clothing such as shorts is formed on the non-skin facing surface of the wing portion 5W. The wing portion 5W is used by being folded back toward the non-skin-facing surface (outer surface) of a crotch portion of clothing such as shorts. In addition, since the wing portion 5W is used by being folded back to the non-skin facing surface (outer surface) side of the crotch portion of clothing, the non-skin facing surface of the wing portion 5W, which is the surface on which the wing adhesive portion is formed, is used when the wing portion 5W is used. Sometimes it is directed toward the wearer's skin, making it the skin-facing surface. Before use, the wing adhesive portion is covered with a release sheet (not shown) made of film, nonwoven fabric, paper, or the like. Further, on both sides of the skin-facing surface of the absorbent main body 5, that is, the skin-facing surface of the top sheet 2 along the longitudinal direction The side sheets 6, 6 are arranged over substantially the entire length of the absorbent main body 5 in the longitudinal direction X1. The pair of side sheets 6, 6 are joined to the top sheet 2 and other members by a known joining means such as an adhesive or hot embossing at joining lines (not shown) extending in the longitudinal direction X1.

In the napkin 1 of this embodiment, the high fiber mass region R is located in the central region B (see FIG. 5). With such a configuration, the high-fiber mass region R can be fitted well to the wearer's excretory area.
The high fiber mass region R may be located only in the central region B. Alternatively, the high fiber mass region R may be located in two regions, the central region B and the front region A adjacent thereto, or in the central region B and the rear region C adjacent thereto. That is, the high fiber mass region R may extend from the front region A to the central region B, or may extend from the rear region C to the central region C.
Further, in the napkin 1, in the high fiber lump region R, it is preferable that the non-skin facing surface side has a higher fiber lump content than the skin facing surface side from the viewpoint of the balance between liquid absorption performance and fit.

Next, a method for manufacturing the absorbent body 4 according to the present invention will be explained using the absorbent body 4 (absorbent core 40) of the embodiment shown in FIGS. 1 to 3 described above as an example.
The absorbent core 40 can be manufactured in accordance with a conventional method using a known fiber stacking device equipped with a rotating drum. The fiber stacking device typically includes a rotating drum in which a stacking recess is formed on the outer circumferential surface, and a core forming material (fiber mass 11, water-absorbing fiber 12F, water-absorbing polymer 13) is conveyed to the stacking recess. and a duct having a flow path inside, and while rotating the rotating drum around the rotation axis along the circumferential direction of the drum, riding the air flow generated in the flow path by suction from the inside of the rotating drum. The core-forming material transported is stacked in the stacking recess. The fiber stack formed in the stacking recess by this stacking process is the absorbent core 40. The specific arrangement of the core forming materials in the absorbent core 40 described above can be realized by appropriately adjusting the stacking order of each core forming material on the rotating drum in the manufacturing method using the fiber stacking device. . The basis weight of the absorbent core 40 is preferably 100 g/m ² or more, more preferably 200 g/m ² or more, and preferably 800 g/m ² or less, more preferably 600 g/m ² or less.

The absorbent body 4 can be manufactured by the following two methods using a known fiber stacking device.
1) A method in which two stacking devices are used to stack and integrate a fiber stack manufactured by one fiber stacking device and a fiber stack manufactured by the other fiber stacking device (hereinafter referred to as the “first method”). (Also referred to as "manufacturing method.")
2) A method in which one fiber stacking device is used and the timing of supplying the fiber mass to the stacking recess is different from that of the water absorbent fibers (hereinafter also referred to as "second manufacturing method").

In the first manufacturing method, first, water-absorbing fibers and, if necessary, a water-absorbing polymer are used as core forming materials, and these water-absorbing materials are accumulated in the accumulation recess of the first fiber stacking device to absorb water. A fiber stack is produced. Separately from this, the fiber agglomerates are accumulated in the accumulating recess of the second fiber stacking device to produce a fiber agglomerate stack. This fiber stack is manufactured so that its length in the longitudinal direction is shorter than that of the water-absorbing fiber stack. Next, the fiber agglomerate stack is stacked at a desired position (for example, the central part in the longitudinal direction) of the water-absorbent fiber stack, and this is pressurized in the thickness direction to form the water-absorbent fiber stack and the fiber agglomerate. The fiber stacks are integrated to obtain a laminate. Alternatively, using suction means such as a known vacuum conveyor, place the water-absorbent fiber pile on the suction surface of the suction means, and while the suction force of the suction surface is acting, the water-absorbent fiber pile is placed on the suction surface of the suction means. A laminate may be obtained by stacking and integrating the fiber mass stack on the body. Regardless of the integration method, entanglement occurs between the water-absorbing fibers and the fiber mass at the interface between the water-absorbent fiber stack and the fiber mass stack. In this way, the absorbent core 40 is obtained. In the absorbent core 40, the portion where the fiber aggregate stack is arranged corresponds to the high fiber aggregate region R.

In the second manufacturing method, a fiber stacking device is used in which the suction force of the stacking recesses is partially different. For example, one is used in which the accumulation recess has a low suction recess and a high suction recess having a higher suction force than the low suction recess. The low suction recess and the high suction recess are connected in the rotational direction (circumferential direction) of a rotating drum included in the fiber stacking device. Then, the stacking device having such a configuration is operated, and while the rotary drum is rotated in the circumferential direction to convey the stacking recess in one direction, the fibers are sucked from the outside of the rotary drum by suction from the inside of the rotary drum. An air flow toward the accumulation recess is generated, and the air flow supplies the core forming material to the accumulation recess and accumulates it (accumulation step). In the accumulation step, first, the fiber mass 11 is supplied to the accumulation recess and is accumulated. At this time, the fiber mass 11 is intensively accumulated in the high suction recess, and a fiber mass stack is formed in the high suction recess. Next, after or during the accumulation of the fiber mass, the water-absorbing fibers 12F and, if necessary, the water-absorbing polymer 13 are supplied to the accumulation recesses and accumulated. At this time, the water-absorbing fibers (water-absorbing polymer) are accumulated in the low suction recess in the accumulation recess, and are also accumulated on the fiber mass 11 accumulated in the high suction recess. In other words, the water-absorbing fiber stack is formed over the entire area of the accumulation recess. In addition, since the fiber mass 11 has air permeability, even when the fiber mass is accumulated in the high suction recess, a suction force capable of sucking the water-absorbing fibers acts on the accumulated fiber mass 11. Therefore, the water-absorbing fibers 12F and the water-absorbing polymer 13 can be accumulated on top of the fiber mass 11 accumulated in the high suction recess. In this way, a laminate of the fiber mass stack and the water-absorbing fiber stack is formed in the high suction recess, and entanglement occurs between the fiber mass and the water-absorbing fibers at the interface between both fiber stacks. In this way, the absorbent core 40 is obtained. In the absorbent core 40, the portion where the fiber mass 11 is intensively accumulated by the high suction recess corresponds to the high fiber mass region R.

The fiber mass 11 will be further explained below. FIG. 6 shows two typical external shapes of the fiber mass 11. The fiber mass 11A shown in FIG. 6(a) has a quadrangular prism shape, more specifically a rectangular parallelepiped shape. The fiber mass 11B shown in FIG. 6(b) has a disk shape. The fiber masses 11A and 11B have in common that they include two base planes 111 that face each other and a body plane 112 that connects the two base planes 111. Both the basic surface 111 and the skeleton surface 112 are portions that are recognized as having substantially no unevenness at a level applied when evaluating the degree of surface unevenness in articles mainly made of fibers of this type.

The rectangular parallelepiped-shaped fiber mass 11A shown in FIG. Each of the four surfaces is a skeleton surface 112. The basic plane 111 and the skeleton plane 112 intersect with each other, and more specifically, are orthogonal to each other.
The disk-shaped fiber mass 11B in FIG. 6(b) has two opposing flat surfaces that are circular in plan view and a curved circumferential surface that connects both flat surfaces. Each of the surfaces is a basic surface 111, and the peripheral surface is a skeleton surface 112.
The fiber masses 11A and 11B also have in common that the skeleton surface 112 has a quadrangular shape, more specifically a rectangular shape, in plan view.

Each of the plurality of fiber masses 11 contained in the absorbent core 40 has two opposing basic surfaces 111 and a skeletal surface 112 connecting both basic surfaces 111, such as fiber masses 11A and 11B shown in FIG. It differs from the amorphous fiber aggregate described above in that it is a "fixed-shaped fiber aggregate." In other words, when any one fiber mass 11 in the absorbent core 40 is viewed through (for example, when observed with an electron microscope), the shape of the fiber mass 11 in perspective differs depending on the viewing angle, and one fiber Where there are many perspective shapes per mass 11, each of the plurality of fiber masses 11 in the absorbent core 40 connects two opposing basic surfaces 111 and both basic surfaces 111 as one of the many transparent shapes. It has a specific perspective shape with a skeletal surface 112. The irregularly shaped fiber aggregates do not substantially have "surfaces" such as the basic surface 111 and the skeletal surface 112, that is, expansive parts, and have different external shapes and are not "fixed".

In this way, when the plurality of fiber masses 11 included in the absorbent core 40 are "shaped fiber aggregates" defined by the basic surface 111 and the skeletal surface 112, the fiber aggregates of irregular shape Since the uniform dispersibility of the fiber aggregates 11 in the absorbent core 40 is improved compared to the case where The effects of improving flexibility, cushioning properties, compression recovery properties, etc.) will be more stably expressed. In particular, in the case of a rectangular parallelepiped-shaped fiber mass 11 as shown in FIG. It becomes possible to have a relatively large number of opportunities for contact with the sexual fibers 12F, and the entangling property increases, which may lead to improvement in shape retention and the like.

In the fiber mass 11, the total area of the two basic surfaces 111 is preferably larger than the total area of the skeleton surfaces 112. That is, in the rectangular parallelepiped-shaped fiber mass 11A in FIG. 6(a), the sum of the areas of the two basic surfaces 111 is larger than the sum of the areas of the four skeletal surfaces 112, and as shown in FIG. 6(b) In the disk-shaped fiber mass 11B, the sum of the areas of the two basic surfaces 111 is larger than the area of the skeleton surface 112 forming the peripheral surface of the disk-shaped fiber mass 11B. In both of the fiber masses 11A and 11B, the basic surface 111 is the surface with the largest area among the plurality of surfaces that the fiber masses 11A and 11B have.

As shown in FIG. 7, a method for producing the fiber mass 11, which is a "shaped fiber aggregate" defined by two basic surfaces 111 and a skeleton surface 112 that intersects both basic surfaces 111, is as shown in FIG. It has a step of cutting the raw material fiber sheet 10bs, which is a raw material, into a regular shape using a cutting means such as a cutter. The raw fiber sheet 10bs is a sheet having the same composition as the fiber mass 11 and larger in size than the fiber mass 11, and is preferably a nonwoven fabric. The plurality of fiber masses 11 produced through such a process are more uniform in shape and size than irregularly shaped fiber aggregates produced by conventional techniques. FIG. 7 is a diagram illustrating a method for manufacturing the rectangular parallelepiped-shaped fiber mass 11A shown in FIG. 6(a), and the dotted line in FIG. 7 indicates a cutting line. The absorbent core 40 contains a plurality of fiber masses 11 having uniform shapes and dimensions, which are obtained by cutting the fiber sheet into regular shapes.

As shown in FIG. 7, the rectangular parallelepiped-shaped fiber mass 11A in FIG. It is manufactured by cutting D2 to a predetermined length. Both directions D1 and D2 are each a predetermined direction in the surface direction of the sheet 10bs, and the sheet 10bs is cut along the thickness direction Z orthogonal to the surface direction. In this way, in the plurality of rectangular parallelepiped-shaped fiber masses 11A obtained by cutting the raw fiber sheet 10bs into so-called dice shapes, the cut surface, that is, the surface that comes into contact with a cutting means such as a cutter when cutting the sheet 10bs, is usually , the skeleton surface 112, and the non-cutting surface, that is, the surface that does not come into contact with the cutting means, is the basic surface 111. The basic surface 111 is the front and back surfaces (the surface orthogonal to the thickness direction Z) of the sheet 10bs, and as described above, is the surface with the largest area among the plurality of surfaces that the fiber mass 11A has.

The above description of the fiber mass 11A basically applies to the disk-shaped fiber mass 11B shown in FIG. 6(b). The only substantial difference from the fiber mass 11A is the cutting pattern of the raw fiber sheet 10bs, and when cutting the sheet 10bs into a regular shape to obtain the fiber mass 11B, according to the plan view shape of the fiber mass 11B, The sheet 10bs may be cut into a circular shape.

Further, the external shape of the fiber mass 11 is not limited to that shown in FIG. 6, and both the basic surface 111 and the skeleton surface 112 are flat surfaces that are not curved like the surfaces 111 and 112 in FIG. 6(a). Alternatively, it may be a curved surface like the skeleton surface 112 (the circumferential surface of the disk-shaped fiber mass 11B) in FIG. 6(b). Further, the basic surface 111 and the skeleton surface 112 may have the same shape and size, and specifically, for example, the outer shape of the fiber mass 11A may be a cube.

The size of the fiber mass 11 is not particularly limited, and can be appropriately set in consideration of the cushioning properties, liquid permeability, etc. of the absorbent core 40. The area of the basic surface 111, which is the surface with the largest area among the plurality of surfaces that the fiber mass 11 has, can be an index of the size of the fiber mass 11. The area of the basic surface 111 of the fiber mass 11 is preferably 1 mm ² or more, more preferably 5 mm ² or more, and preferably 100 mm ² or less, more preferably 50 mm ^{2 or} less.

Preferred examples of the fiber mass 11 include those in which the aspect ratio of the basic surface 111 is 1 or close to 1, that is, the basic surface 111 has a square shape in plan view or a shape similar thereto. When such a fiber mass 11 is used in the absorbent core 40, the absorbent core 40 tends to become bulky, and cushioning properties etc. can be improved.

When the basic surface 111 has a quadrangular shape in plan view, the aspect ratio of the basic surface 111 is determined as the ratio of the lengths of two mutually orthogonal sides defining the basic surface 111 of the quadrilateral. If the lengths of the two sides are the same, the aspect ratio of the basic surface 111 having a rectangular shape in plan view is 1. If the lengths of the two sides are different from each other, that is, the shape of the basic surface 111 in plan view is ), it is determined as the ratio (L12/L11) of the length L12 of the long side 111b to the length L11 of the short side 111a. In addition, when the shape of the basic surface 111 in plan view is not a quadrangle, as in the case of the fiber mass 11B shown in FIG. It is calculated as the ratio of If the lengths of the two axes are the same, the aspect ratio of the basic surface 111 of a non-quadrangular shape in plan view is 1, and if the lengths of the two axes are different from each other, that is, the length is relatively short. If there is a long axis that is relatively long to the short axis, the ratio of the length of the long axis (the length indicated by the symbol L12 in FIG. 6(b)) to the length of the short axis (latter/former ) is required.

The dimensions of each part of the fiber mass 11 (11A, 11B) can be set as follows, for example. The dimensions of each part of the fiber mass 11 can be measured based on an electron micrograph of the fiber mass 11 or the like.
When the basic surface 111 has a rectangular shape in plan view as shown in FIG. 6(a), the length L11 of the short side 111a is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm. The length is preferably 10 mm or less, more preferably 6 mm or less, and even more preferably 5 mm or less.
The length L12 of the long side 111b of the basic surface 111 having a rectangular shape in plan view is preferably 0.3 mm or more, more preferably 1 mm or more, even more preferably 2 mm or more, and preferably 30 mm or less, more preferably 15 mm or less, More preferably, it is 10 mm or less.
Note that, as shown in FIG. 6, when the basic surface 111 is the surface having the largest area among the plurality of surfaces that the fiber mass 11 has, the length L12 of the long side 111b is the maximum length across the fiber mass 11. (length of the major axis), and the maximum length across the length corresponds to the diameter of the circular basic surface 111 in the disk-shaped fiber mass 11B in a plan view.
The thickness T of the fiber mass 11, that is, the length T between the two opposing basic surfaces 111, is preferably 0.1 mm or more, more preferably 0.3 mm or more, and preferably 10 mm or less, more preferably 6 mm or less. be.

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

The fiber ends present on each surface (basic surface 111, skeleton surface 112) of the fiber mass 11 are located between the fiber mass 11 and other fiber mass 11 included in the absorbent core 40 or the water absorbent fibers 12F. Useful for forming confounds. In general, the greater the number of fiber ends per unit area, the better the intertwining properties, which can lead to improvements in various properties such as shape retention of the absorbent core 40. As mentioned above, the number of fiber ends per unit area on each surface of the fiber mass 11 is not uniform, and the number of fiber ends per unit area is "skeletal surface 112>basic surface 111". Since the size relationship is established, the degree of entanglement with other fibers (other fiber masses 11, water-absorbing fibers 12F) via the fiber mass 11 varies depending on the surface of the fiber mass 11, and the skeletal surface 112 is different from the basic surface 111. It is highly confounding compared to In other words, the bonding force through intertwining with other fibers via the skeletal surface 112 is stronger than that via the basic surface 111, and in one fiber mass 11, the bonding force between the basic surface 111 and the skeletal surface is stronger. 112 may cause a difference in bond strength with other fibers. Generally, the stronger the bonding force is, the more the freedom of movement of the bonded fibers is restricted, and while the strength (shape retention) of the absorbent core 40 as a whole improves, the softness tends to decrease. .

In this way, in the absorbent core 40, each of the plurality of fiber masses 11 contained therein has two types of bonding force with respect to other fibers (other fiber masses 11, water absorbent fibers 12F) around it. As a result, the absorbent core 40 has appropriate softness and strength (shape retention). When the absorbent core 40 having such excellent properties is used as an absorbent body of an absorbent article according to a conventional method, it can provide a comfortable wearing feeling to the wearer of the absorbent article. At the same time, the inconvenience of the absorbent core 40 being destroyed by external forces such as the wearer's body pressure when worn is effectively prevented.

In particular, in the fiber mass 11 (11A, 11B) shown in FIG. 6, the total area of the two basic surfaces 111 is larger than the total area of the skeleton surface 112, as described above. For this reason, the basic surface 111, which has a relatively small number of fiber ends per unit area and therefore has a relatively low entanglement with other fibers, is better than the skeletal surface 112, which has the opposite properties. This means that the total area is larger. Therefore, the fiber lumps 11 (11A, 11B) shown in FIG. ), and even if they are entangled with other surrounding fibers, they are easily entangled with a relatively weak bonding force, so they are difficult to form into large clumps, and the absorbent core 40 has excellent flexibility. It can give gender.

The constituent fibers 11F of the fiber mass 11 include synthetic fibers such as thermoplastic fibers. It is preferable to use thermoplastic fibers as the fibers 11F. Such thermoplastic fibers preferably have lower water absorbency (weak water absorbency) than the water absorbent fiber 12F, and non-water absorbent thermoplastic fibers are particularly preferred. The constituent fibers 11F of the fiber mass 11 may contain fiber components other than thermoplastic fibers (for example, natural fibers), but since the constituent fibers 11F of the fiber mass 11 include weakly hydrophilic fibers, preferably non-water absorbing fibers, The effects (shape retention, Improved flexibility, cushioning properties, compression recovery properties, resistance to twisting, etc.) can be stably achieved.
The content of synthetic fibers as the constituent fibers 11F in the fiber mass 11 is preferably 90% by mass or more with respect to the total mass of the fiber mass 11, and is 100% by mass, that is, the content of the synthetic fibers as the constituent fibers 11F is 100% by mass, that is, the content of the synthetic fibers as the constituent fibers 11F is 100% by mass or more. It is most preferable to be present. In particular, when thermoplastic fibers are included as the constituent fibers 11F, the effects resulting from the presence of the fiber mass 11 described above are more stably achieved.

When thermoplastic fibers are used as the fibers 11F, the thermoplastic fibers preferably have low water absorption.
As used herein, the term "water-absorbing" is easily understood by those skilled in the art, for example, as in the phrase "pulp is water-absorbing". Similarly, it can be easily understood that thermoplastic fibers are weakly water-absorbent (in particular, non-water-absorbent). On the other hand, the degree of water absorbency of fibers can be determined by the moisture content measured by the method described below, allowing comparison of relative differences in water absorbency and also defining a more preferable range. The higher the moisture content value, the stronger the water absorbency of the fiber. The moisture content of the water absorbent fiber 12F is preferably 6% or more, more preferably 10% or more. On the other hand, the moisture content of the thermoplastic fiber is preferably less than 6%, more preferably less than 4%. Note that when the moisture content is less than 6%, the fiber can be determined to be a non-water-absorbing fiber.

<Method for measuring moisture content>
The moisture content was calculated by applying the moisture content test method of JIS P8203. That is, the fiber sample was allowed to stand for 24 hours in a test room with a temperature of 40° C. and a relative humidity of 80% RH, and then the weight W (g) of the fiber sample before absolute drying was measured in that room. Thereafter, the fiber sample was left to stand still for 1 hour in an electric dryer (for example, manufactured by Isuzu Seisakusho Co., Ltd.) at a temperature of 105±2° C. to completely dry the fiber sample. After the absolute drying process, in a test room under standard conditions at a temperature of 20 ± 2°C and a relative temperature of 65 ± 2%, the fiber sample was wrapped in Saran Wrap (registered trademark) manufactured by Asahi Kasei Corporation, and Si silica gel (for example, Toyoda Kako Co., Ltd.) is placed in a glass desigator (for example, manufactured by Techjam Co., Ltd.) and allowed to stand until the fiber sample reaches a temperature of 20±2°C. Thereafter, the constant weight W' (g) of the fiber sample is weighed, and the moisture content of the fiber sample is determined using the following formula.
Moisture percentage (%) = [(W-W')/W'] x 100

Similarly, from the viewpoint of ensuring that the absorbent core 40 exhibits excellent effects in shape retention, flexibility, cushioning properties, compression recovery properties, resistance to twisting, etc. in both dry and wet states. Preferably, the fiber mass 11 has a three-dimensional structure in which a plurality of thermoplastic fibers are heat-fused to each other.

In order to obtain a fiber mass 11 in which a plurality of heat-sealed parts are three-dimensionally dispersed, it is sufficient that the raw fiber sheet 10bs (see FIG. 7) has the same structure. The raw fiber sheet 10bs in which the fused portions are three-dimensionally dispersed can be manufactured by subjecting a web or nonwoven fabric mainly composed of thermoplastic fibers to heat treatment such as hot air treatment, as described above.

It is preferable that the resin constituting the synthetic fiber is a thermoplastic resin. Examples of thermoplastic resins include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid, polymethacrylic acid alkyl ester, polyvinyl chloride, and polyvinylidene chloride. One type of these can be used alone or two or more types can be used in combination. Note that the fiber 11F may be a single fiber made of one type of synthetic resin or a blended polymer of two or more types of synthetic resin, or may be a composite fiber. The composite fiber referred to here is a synthetic fiber obtained by combining two or more types of synthetic resins with different components using a spinneret and spinning them simultaneously, and has a structure in which multiple components are continuous in the length direction of the fiber. Refers to things that are bonded to each other within the fibers. The form of the composite fiber includes a core-sheath type, a side-by-side type, etc., and is not particularly limited.

Further, it is preferable that the fiber mass 11 has a contact angle with water of less than 90 degrees, particularly 70 degrees or less, from the viewpoint of further improving the ability to draw body fluids during initial excretion. Such fibers can be obtained by treating the non-water-absorbing thermoplastic fibers described above with a hydrophilic agent according to a conventional method. As the hydrophilic agent, a common surfactant can be used.

<Method of measuring contact angle>
A fiber is removed from the object to be measured (absorbent core) and the contact angle of water to the fiber is measured. As a measuring device, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. Deionized water is used to measure contact angles. The amount of liquid ejected from an inkjet type water droplet ejection unit (manufactured by Cluster Technology, pulse injector CTC-25 with an ejection port pore diameter of 25 μm) is set to 20 picoliters, and water droplets are dropped directly above the fibers. The dripping process is recorded on a high-speed recording device connected to a horizontally installed camera. From the viewpoint of later image analysis, the recording device is preferably a personal computer with a built-in high-speed capture device. In this measurement, images are recorded every 17 msec. In the recorded video, the first image of a water droplet landing on the fiber is captured using the included software FAMAS (software version 2.6.2, analysis method is droplet method, analysis method is θ/2 method, image processing algorithm Image analysis is performed with no reflection, image processing image mode is frame, threshold level is 200, and no curvature correction), and the angle between the surface of the water droplet that touches the air and the fiber is calculated, and the contact Let it be a corner. The fibers taken out from the object to be measured are cut into fiber lengths of 1 mm, placed on a sample stand of a contact angle meter, and maintained horizontally. The contact angle is measured at two different locations for each fiber. The contact angle of N = 5 pieces is measured to one decimal place, and the average value of the measured values at a total of 10 locations (rounded to the second decimal place) is defined as the contact angle of the fiber with water. The measurement environment is a room temperature of 22±2° C. and a humidity of 65±2% RH.

Regarding the absorbent core (absorbent core) to be measured, when the absorbent core is taken out from the absorbent article, if the absorbent core is fixed to other constituent members with adhesive, fusion, etc. The fixed portion is removed after the adhesive force is removed by a method such as blowing cold air on it within a range that does not affect the contact angle of the fibers. This procedure is common to all measurements herein.

Although the present invention has been described above based on the embodiments thereof, the present invention is not limited to the embodiments and can be modified as appropriate.
For example, in the absorbent body 4 of the embodiment described above, the fiber lumps 11 are unevenly distributed on one side in the high fiber lump region R (see FIG. 2), but the distribution of the fiber lumps 11 in the thickness direction Z is as follows. but not limited to. Specifically, as in the absorbent body 4b shown in FIG. good. In such a form, the water-absorbing material (the water-absorbing fibers 12F and the water-absorbing polymer 13) is also uniformly distributed in the thickness direction Z together with the fiber mass 11.
The absorbent article of the present invention includes a wide range of articles used to absorb body fluids (urine, soft stool, menstrual blood, sweat, etc.) discharged from the human body, and includes, in addition to the above-mentioned sanitary napkins, sanitary shorts, and Included are so-called expandable disposable diapers with tape, pants-type disposable diapers, incontinence pads, and the like.

1 Sanitary napkins (absorbent articles)
2 Top sheet 3 Back sheet 4 Absorbent body 7 Notch portion 40 Absorbent core 41 Core wrap sheet 11 Fiber mass 11F Constituent fibers of fiber mass 111 Basic surface 112 Skeletal surface 12F Water absorbent fiber 13 Water absorbent polymer 10bs Raw material fiber of fiber mass Sheet A Front region B Central region C Rear region R High fiber mass region R2 Low fiber mass region R3 Notch region

Claims (6)

An absorbent body having a longitudinal direction and a width direction perpendicular to the longitudinal direction,
comprising an absorbent core containing a plurality of fiber masses including water absorbent fibers and synthetic fibers,
The absorbent core has a low fiber mass region where the basis weight of the fiber mass is 50 g/m ² or less and a high fiber mass region where the basis weight of the fiber mass is 100 g/m ² or more. ,
The low fiber mass region has a pair of notches extending inward in the width direction from each of both side edges along the longitudinal direction, and is defined as an area sandwiched between the pair of notches. An absorbent body that includes the entire notched area. The low fiber mass region is provided on each side of the high fiber mass region in the longitudinal direction, and the high fiber mass region is arranged between the cutout regions located in each of these low fiber mass regions. The absorbent body according to claim 1. Each of the pair of notches has an inner end located innermost in the width direction, and the inner end is biased toward the high fiber mass region in the longitudinal direction. The absorbent body according to claim 1 or 2. The absorbent article according to any one of claims 1 to 3, comprising a core wrap sheet that covers the absorbent core, and the core wrap sheet is cut out along the notch. The high fiber mass region has a ratio of the mass of the fiber mass to the total mass of the fiber mass and the water-absorbing fibers on one side of the two surfaces with the largest area in the absorbent body than on the other side. The absorbent body according to any one of claims 1 to 4, which has a high The absorbent body according to any one of claims 1 to 5, a top sheet disposed on the skin-facing side of the absorbent body, and a back sheet disposed on the non-skin-facing side of the absorbent body. An absorbent article comprising:
A central region including a region facing the wearer's excretory area, a front region located on the ventral side of the wearer from the central region, and a rear region located on the dorsal side of the wearer from the central region. It has
An absorbent article, wherein the high fiber mass region is located within the central region.