WO2023119592A1

WO2023119592A1 - Non-woven fabric for liquid permeable sheet of absorbent article

Info

Publication number: WO2023119592A1
Application number: PCT/JP2021/048014
Authority: WO
Inventors: 耕出谷; 明寛木村; 賢一郎黒田; 菜緒子小森
Original assignee: ユニ・チャーム株式会社
Priority date: 2021-12-23
Filing date: 2021-12-23
Publication date: 2023-06-29

Abstract

Provided is a non-woven fabric for a liquid permeable sheet of an absorbent article that has excellent water-absorbing properties and inhibits sticking to the skin of a wearer. This non-woven fabric 10 comprises a first fiber layer 26 and a second fiber layer 28, wherein the first fiber layer 26 is made of thermoplastic resin fibers, and the second fiber layer 28 contains water-absorbent fibers and thermoplastic resin fibers, and has a plurality of protrusions 30 and a plurality of recesses 32. In the case in which a load is not added in the thickness direction to the non-woven fabric 10 when the thickness of the first fiber layer 26 at the plurality of protrusions 30 and the thickness of the first fiber layer 26 at the plurality of recesses 32 are defined as Tc1 and Td1, respectively, and in the case in which a load of 2.9 kPa is added to the non-woven fabric 10 in the thickness direction when the thickness of the first fiber layer 26 at the plurality of protrusions 30 and the thickness of the first fiber layer 26 at the plurality of recesses 32 are defined as Tc2 and Td2, respectively, the non-woven fabric 10 satisfies the relational expression of (Tc2/Tc1)<(Td2/Td1).

Description

Non-woven fabric for liquid-permeable sheets of absorbent articles

The present invention relates to nonwoven fabrics for liquid-permeable sheets of absorbent articles.

In absorbent articles such as disposable diapers and sanitary napkins, the use of a nonwoven fabric with a two-layer structure as a material for liquid-permeable sheets such as surface sheets is being studied.

For example, in Patent Document 1, a first fiber layer and a second fiber layer located on one main surface of the first fiber layer are included, the first fiber layer includes a first core-sheath type conjugate fiber, and a first The two fiber layers contain a second core-sheath type conjugate fiber and a cellulosic fiber, the fineness of the first core-sheath type conjugate fiber is smaller than the fineness of the second core-sheath type conjugate fiber, and the fineness of the first core-sheath type conjugate fiber is The fineness is 1.0 to 2.8 dtex, the fineness of the second core-sheath type composite fiber is 1.7 to 5.6 dtex, the fineness of the cellulosic fiber is 1.2 to 6.0 dtex, and the second A nonwoven fabric for absorbent articles is disclosed in which the fibrous layer contains 5% to 40% by weight of cellulosic fibers based on the total weight of the second fibrous layer.

JP 2020-171688 A

In addition to liquid excretion such as menstrual blood excreted by the wearer, moisture such as sweat discharged from the wearer's skin is supplied to the absorbent article.

In the nonwoven fabric of Patent Document 1, since the thickness of the first fiber layer is uniform in the surface direction, when the thickness of the first fiber layer is large, the first fiber layer receives the excrement and the non-skin-facing side absorber However, the first fiber layer prevents water absorption by the cellulosic fibers, and moisture such as sweat remains between the wearer's skin and the absorbent article, giving the wearer discomfort due to stuffiness. There is a concern that When the thickness of the first fiber layer is thin, the distance between the cellulosic fibers and the wearer's skin is short, so that the cellulosic fibers absorb water. The surface of the non-woven fabric sticks to the wearer's skin, which may cause rashes and itchiness on the wearer's skin.

An object of the present invention is to provide a nonwoven fabric for a liquid-permeable sheet of an absorbent article that has excellent water absorbency and suppresses sticking to the wearer's skin.

The present invention provides a nonwoven fabric for a liquid-permeable sheet of an absorbent article comprising a first fiber layer and a second fiber layer in order in the thickness direction, wherein the first fiber layer is made of thermoplastic resin fibers, It has a first surface that is the skin-facing surface of the liquid-permeable sheet, the second fiber layer contains water-absorbing fibers and thermoplastic resin fibers, and the second surface that is the non-skin-facing surface of the liquid-permeable sheet. The first surface has a plurality of solid protrusions protruding in a direction from the second surface toward the first surface, and depressions in a direction from the first surface toward the second surface. The thickness of the first fiber layer in the plurality of recesses is thinner than the thickness of the first fiber layer in the plurality of protrusions, and a load is applied in the thickness direction. In the nonwoven fabric, the thickness of the first fiber layer in the plurality of protrusions and the thickness of the first fiber layer in the plurality of recesses are Tc1 and Td1, respectively, and a load of 2.9 kPa is applied in the thickness direction In the added nonwoven fabric, when the thickness of the first fiber layer in the plurality of protrusions and the thickness of the first fiber layer in the plurality of recesses are Tc2 and Td2, respectively, (Tc2/Tc1) < ( It is a nonwoven fabric that satisfies the relational expression Td2/Td1).

The nonwoven fabric according to the present invention has excellent water absorbency and suppresses sticking to the wearer's skin.

It is a figure which shows typically the absorbent article which concerns on embodiment. It is a top view which shows typically the nonwoven fabric which concerns on embodiment. FIG. 3 is a partial cross-sectional view schematically showing a cross section taken along line III-III of FIG. 2; FIG. 3 is a partial cross-sectional view schematically showing a cross section taken along line III-III of FIG. 2, showing a state in which a load in the thickness direction is applied to the nonwoven fabric.

The embodiments of the present invention relate to the following aspects.

[Aspect 1]
A nonwoven fabric for a liquid-permeable sheet of an absorbent article comprising a first fiber layer and a second fiber layer in order in the thickness direction,
The first fiber layer is made of thermoplastic resin fibers and has a first surface that is the skin-facing surface of the liquid-permeable sheet,
The second fiber layer contains water-absorbent fibers and thermoplastic resin fibers, and has a second surface that serves as a non-skin facing surface of the liquid-permeable sheet,
a plurality of solid convex portions protruding in a direction from the second surface toward the first surface and a plurality of concave portions recessed in a direction from the first surface toward the second surface on the first surface; has
The thickness of the first fiber layer in the plurality of recesses is thinner than the thickness of the first fiber layer in the plurality of protrusions,
In the nonwoven fabric to which a load is not applied in the thickness direction, the thickness of the first fiber layer in the plurality of protrusions and the thickness of the first fiber layer in the plurality of recesses are Tc1 and Td1, respectively; In the nonwoven fabric to which a load of 2.9 kPa is applied in the thickness direction, the thickness of the first fiber layer in the plurality of protrusions and the thickness of the first fiber layer in the plurality of recesses are Tc2 and Td2, respectively. A nonwoven fabric that satisfies the relational expression of (Tc2/Tc1)<(Td2/Td1) when .

The nonwoven fabric includes a first fiber layer and a second fiber layer, the first fiber layer made of thermoplastic resin fibers, the second fiber layer including water-absorbent fibers and thermoplastic resin fibers, and a plurality of protrusions and a plurality of recesses, when used in a liquid-permeable sheet (for example, a top sheet) of an absorbent article, the protrusions on the skin-facing surface (first surface) come into contact with the wearer's skin, The thermoplastic resin fibers of the projections receive excrement such as menstrual blood excreted from the wearer, and transfer the excrement to the absorber located on the non-skin facing side (second surface) through the second fiber layer.
Moisture such as sweat discharged from the wearer's skin is in the state of water droplets or vapor, and unlike excrement such as menstrual blood, it is mainly released from the wearer's skin rather than moving in the thickness direction of the first fiber layer. The recess is reached directly or along the first surface. In this nonwoven fabric, since the thickness of the first fiber layer in the plurality of recesses is thinner than the thickness of the first fiber layer in the plurality of protrusions, the distance from the first surface of the recesses to the second fiber layer is the first distance in the protrusions. It is shorter than the distance from the surface to the second fiber layer, and moisture such as sweat easily reaches the second fiber layer in the plurality of recesses. Therefore, in this nonwoven fabric, the water-absorbent fibers contained in the second fiber layer of the recesses easily absorb moisture such as sweat discharged from the wearer's skin, and the thermoplastic resin contained in the second fiber layer The fibers transfer the moisture to the absorbent body located on the non-skin facing surface (second surface) side.
In this nonwoven fabric, the thickness of the first fiber layer in the protrusions and the thickness of the first fiber layer in the recesses before and after applying a load in the thickness direction satisfy the above relational expression, so that the thickness of the first fiber layer in the protrusions is The rate of decrease in thickness in the concave portion is higher than that in the first fiber layer. Therefore, when the present nonwoven fabric is subjected to the body pressure of the wearer, the distance from the first surface to the second fiber layer is reduced even in the protrusions, and moisture such as sweat discharged from the wearer's skin is reduced. , it becomes easier to reach the second fiber layer through the first fiber layer of the convex portion. Part of the moisture is absorbed by the water-absorbent fibers contained in the second fiber layer, and the other part is located on the non-skin facing surface (second surface) side by the thermoplastic resin fibers contained in the second fiber layer. Transfer to absorber. As described above, when the present nonwoven fabric is subjected to body pressure of the wearer, the water-absorbing fibers can absorb moisture such as sweat expelled from the wearer's skin even in the convex portions.
Even when the second fiber layer absorbs water such as perspiration of the wearer and excretions excreted by the wearer, the nonwoven fabric keeps the absorbent fibers contained in the second fiber layer away from the wearer's skin. By holding the first fiber layer of the protrusions in the raised position, the first surface is prevented from sticking to the wearer's skin.
As described above, the present nonwoven fabric can provide a nonwoven fabric for a liquid-permeable sheet of an absorbent article that has excellent water absorbency and suppresses sticking to the wearer's skin.

[Aspect 2]
The basis weights of the first fiber layer and the second fiber layer are uniform in the plane direction,
Aspect 1, wherein in the nonwoven fabric to which a load of 2.9 kPa is applied in the thickness direction, the thickness of the first fiber layer in the plurality of protrusions is thinner than the thickness of the first fiber layer in the plurality of recesses. The nonwoven fabric described in .

In the convex portions of the present nonwoven fabric, the basis weights of the first fiber layer and the second fiber layer are uniform in the surface direction, and the thickness of the first fiber layer in the concave portions is thinner than the thickness of the first fiber layer in the convex portions. Since the thickness of the first fiber layer in the convex portion is thicker than the thickness of the first fiber layer in the concave portion, the fiber density of the first fiber layer in the convex portion is lower than that in the concave portion, and deformation in the thickness direction is easier. Moreover, since the load in the thickness direction acts on the convex portion from the first surface and the second surface, when the load is applied in the thickness direction, the thickness of the convex portion is more likely to decrease than that of the concave portion. On the other hand, in the recesses, the basis weights of the first fiber layer and the second fiber layer are uniform in the surface direction, and the thickness of the first fiber layer in the recesses is thinner than the thickness of the first fiber layer in the protrusions. The fiber density of the first fiber layer is high, and the first fiber layer is difficult to deform in the thickness direction. Furthermore, in the present nonwoven fabric, as long as the protrusions protrude from the recesses in the thickness direction on the first surface, almost no load acts on the recesses in the thickness direction. Therefore, in this nonwoven fabric, even when a load is applied in the thickness direction, the thickness of the first fiber layer in the concave portions is less likely to change than the thickness of the first fiber layer in the convex portions.
In this nonwoven fabric, when the load in the thickness direction is 2.9 kPa, the thickness of the first fiber layer in the convex portion is reduced while maintaining the shape in which the convex portion protrudes in the thickness direction from the concave portion on the first surface. However, since the thickness of the first fiber layer in the convex portion is thinner than the thickness of the first fiber layer in the concave portion, the distance from the first surface to the second fiber layer is shorter in the convex portion as well. Therefore, when the present nonwoven fabric is subjected to the body pressure of the wearer, the water-absorbent fibers can absorb moisture such as perspiration discharged from the wearer's skin even in the convex portions.

[Aspect 3]
In the nonwoven fabric to which a load of 2.9 kPa is applied in the thickness direction, the deepest part of the plurality of recesses is a position recessed from the first surface toward the second surface from the highest part of the plurality of protrusions. 3. The nonwoven fabric according to

aspect

1 or 2.
When a load of 2.9 kPa is applied in the thickness direction, that is, when the body pressure of the wearer is applied to the nonwoven fabric, the deepest part of the plurality of recesses becomes a plurality of protrusions while the protrusions receive the above load. maintains a shape that is recessed toward the second surface from the highest part of the Therefore, the present nonwoven fabric suppresses sticking to the wearer's skin by preventing the concave portions from coming into contact with the wearer's skin.

[Aspect 4]
The nonwoven fabric according to any one of aspects 1 to 3, wherein the second fiber layer contains 30% by mass to 70% by mass of the water absorbent fiber.
Since the nonwoven fabric contains 30% to 70% by mass of water-absorbing fibers and thermoplastic resin fibers in the second fiber layer, the water-absorbing fibers absorb moisture such as sweat discharged from the wearer's skin. At the same time, excrement excreted from the wearer is transferred to the non-skin facing side by the thermoplastic resin fibers.

[Aspect 5]
The fiber diameter of the thermoplastic resin fibers of the second fiber layer is smaller than the fiber diameter of the thermoplastic resin fibers of the first fiber layer,
The nonwoven fabric according to any one of aspects 1 to 4, wherein the intersections of the thermoplastic resin fibers are thermally bonded in each of the first fiber layer and the second fiber layer.
Since the second fiber layer has a smaller fiber diameter, the thermoplastic resin fibers are more likely to be thermally bonded to each other. hard. On the other hand, since the first fiber layer has a larger fiber diameter, it is more difficult to thermally bond than the thermoplastic resin fibers of the second fiber layer.
Therefore, in the present nonwoven fabric, since the easily deformable first fiber layer in the protrusions is supported from the second surface side by the hard-to-deform second fiber layer, when a load is applied in the thickness direction, the thickness of the protrusions increases. By decreasing, the distance from the first surface to the second fiber layer is shortened even in the convex portion, and the water-absorbing fibers can absorb moisture such as sweat discharged from the wearer's skin.

[Aspect 6]
The nonwoven fabric according to any one of aspects 1 to 5, comprising a third layer made of thermoplastic resin fibers on the second surface side.
Since the nonwoven fabric is provided with the third fiber layer on the second surface side, when the body pressure of the wearer is received, the first fiber layer and the second fiber layer and the third fiber layer are applied to the second and third fiber layers. Since it is supported from the surface side, when a load is applied in the thickness direction, the thickness of the first fiber layer at the convex portion tends to decrease. Therefore, when the present nonwoven fabric is subjected to the body pressure of the wearer, the distance from the first surface to the second fiber layer is shortened even in the protrusions, and the water-absorbent fibers absorb perspiration and the like discharged from the wearer's skin. can absorb moisture.

[Aspect 7]
The nonwoven fabric according to any one of aspects 1 to 6, wherein part of the water absorbent fibers are exposed from the first surface.
Since part of the water-absorbing fibers of this nonwoven fabric is exposed from the first surface, when it is used as a liquid-permeable sheet of an absorbent article, the water-absorbing fibers exposed from the skin-facing surface (first surface) Since moisture such as perspiration discharged from the wearer's skin is easily transferred to the second fiber layer through a part thereof, it is excellent in water absorption.

Hereinafter, nonwoven fabrics for liquid-permeable sheets of absorbent articles according to embodiments will be described in detail with reference to the drawings.

(Structure of sanitary napkin)
The absorbent article 1 shown in FIG. 1 is a sanitary napkin, and has a longitudinal direction L, a width direction W and a thickness direction T which are orthogonal to each other. A pair of flap portions 1B extending on both sides in the width direction W are provided in the center. Since the longitudinal direction L, width direction W and thickness direction T of the absorbent article 1 and the longitudinal direction, width direction and thickness direction of each material to be described later coincide with each other, the absorbent article 1 and its respective materials will be described below. The longitudinal direction L, the width direction W and the thickness direction T are used in common. The terms "skin facing side" and "non-skin facing side" refer to the side relatively close to the wearer's skin surface in the thickness direction T when the absorbent article 1 is worn by the wearer of the absorbent article 1. and the far side, respectively, and are commonly used for each material of the absorbent article 1 . In the present specification, the absorbent article and each material constituting the absorbent article (e.g., topsheet, absorbent core, backsheet, etc.) are referred to as the "skin-facing surface" and the "non-skin-facing surface." are sometimes referred to simply as the "skin-facing surface" and the "non-skin-facing surface", respectively.

The absorbent article 1 comprises a topsheet 2, an absorbent body 3 and a backsheet 4 in this order from the side facing the skin. The topsheet 2 is a liquid-permeable sheet positioned on the wearer's skin facing side. The absorber 3 is a liquid-absorbing and liquid-retaining material positioned between the topsheet 2 and the backsheet 4 . Examples of the absorber 3 include pulp fibers, synthetic fibers, and absorbent polymers. The back sheet 4 is a liquid-impermeable sheet positioned on the non-skin facing side of the wearer. Examples of the backsheet 4 include liquid-impermeable non-woven fabrics, synthetic resin films, composite sheets thereof, SMS non-woven fabrics, and other liquid-impermeable sheets. An exterior sheet 9 that reinforces the backsheet 4 and improves the touch may be laminated on the non-skin facing side of the backsheet 4 . As the exterior sheet 9, any water-repellent sheet such as the same material as the back sheet 4, a water-repellent nonwoven fabric, a synthetic resin film, or a composite sheet thereof can be used. The absorbent body 3, the topsheet 2 and the backsheet 4 are bonded together with an adhesive. As the adhesive for bonding between the top sheet 2, the absorbent body 3 and the back sheet 4, a known material generally used in the absorbent article 1, such as a thermoplastic adhesive, can be used.

(surface sheet)
The surface sheet 2 will be described below with reference to FIGS. 2 to 4. FIG. The surface sheet 2 is made of the nonwoven fabric 10 according to this embodiment. The topsheet 2 has a longitudinal direction L, a width direction W and a thickness direction T, and has a first surface 22 on one side and a second surface 24 on the opposite side of the first surface 22 . The first surface 22 and the second surface 24 intersect the thickness direction T, respectively. One of the thickness directions T is upward and the other direction is downward.

The nonwoven fabric 10 includes the first fiber layer 26 and the second fiber layer 28 in the thickness direction T in the above order. The first fiber layer 26 is made of thermoplastic resin fibers and has a first surface 22 that is the skin-facing surface of the top sheet 2 (liquid-permeable sheet). The nonwoven fabric 10 is not particularly limited as long as it can be used as a surface sheet, but is preferably a thermal bonded nonwoven fabric in which thermoplastic resin fibers are thermally bonded together, and more preferably an air-through nonwoven fabric.

The second fiber layer 28 contains water-absorbent fibers and thermoplastic resin fibers, and has a second surface 24 that serves as the non-skin-facing surface of the topsheet 2 . The second fiber layer 28 preferably contains 30% to 70% by weight, more preferably 40% to 60% by weight, of absorbent fibers. A portion of the absorbent fibers may penetrate through the first fiber layer 26 and be exposed from the first surface 22 .

The nonwoven fabric 10 may further include a third fiber layer 36 made of thermoplastic resin fibers on the second surface 24 side. That is, the nonwoven fabric 10 may include the first fiber layer 26, the second fiber layer 28 and the third fiber layer 36 in the thickness direction T in this order. The same material as the first fiber layer 26 can be used for the third fiber layer 36 . The third fiber layer 36 is in contact with the second fiber layer 28 on the surface facing the skin. When the nonwoven fabric 10 is provided with the third fiber layer 36 , the non-skin facing surface of the third fiber layer 36 is the second surface 24 of the nonwoven fabric 10 .

The nonwoven fabric 10 has a plurality of solid protrusions 30 protruding from the second surface 24 toward the first surface 22 and recessed from the first surface 22 toward the second surface 24 on the first surface 22. and a plurality of recesses 32 . As used herein, the term “solid” means that the projection 30 does not have a space with a significantly lower fiber density than its surroundings, which hinders the movement of liquid. When the height difference between the highest portion 31 where the height of the first surface 22 is highest and the deepest portion 33 where the height of the first surface 22 is lowest is d, the position at a height of d/2 from the deepest portion 33 A portion projecting upward from the edge can be referred to as a convex portion 30 and a portion recessed downward can be referred to as a concave portion 32 .

In the nonwoven fabric 10, the thickness Td1 of the first fiber layer 26 in the concave portion 32 is thinner than the thickness Tc1 of the first fiber layer 26 in the convex portion 30. Here, the thickness Td1 of the first fiber layer 26 at the recess 32 is the thickness of the first fiber layer 26 at the deepest portion 33, and the thickness Tc1 of the first fiber layer 26 at the protrusion 30 is the first thickness at the highest portion 31. It is the thickness of the fiber layer 26 .

The thickness of each part of the first fiber layer 26 and the second fiber layer 28 of the nonwoven fabric 10 is measured by the following method. First, the hydrophilic fiber is dyed, and then the thickness of each part is measured. Dyeing of hydrophilic fibers is carried out according to the following procedure. (1) Prepare a nonwoven fabric whose thickness is to be measured. (2) Pour 1 L of water into a pot and heat to 60°C to 70°C. (3) Put the reagent Kayastain Q (Shikisensha Co., Ltd.) into the pot of (2) and dissolve. (4) Heat the pan to 80°C. (5) Put the non-woven fabric into the pot of (4) and leave it for 30 minutes. (5) After that, the nonwoven fabric is washed with running water. (6) Dry in an oven at 80°C for 1 hour. As a result of the above procedure, the absorbent fibers are dyed blue and the thermoplastic fibers are dyed yellow.

　The thickness is measured according to the following procedure. (1) The dyed nonwoven fabric is cut into a sample having a length of 5 mm in the machine direction (MD) and a length of 20 mm in the transverse direction (CD). (2) Fix the sample on a jig with double-sided tape so that the CD cross section can be observed. (3) Take an enlarged photograph of the cross section with a digital microscope VHX-7000 manufactured by Keyence Corporation, select the distance between two points of plane measurement, and the thickness of each part of the first fiber layer and the second fiber layer of the nonwoven fabric to measure.

The dimensions of the projections 30 include, for example, a width of 0.25 to 5 mm, a height of 0.25 to 5 mm, and a pitch of 0.5 to 10 mm. The dimensions of these projections 30 can be measured from a planar photograph or planar image obtained by observing the non-woven fabric 10 in a non-pressurized state with an enlarged observation means such as a scanning electron microscope.

As shown in FIG. 2, the plurality of protrusions 30 are formed as a plurality of ridges extending continuously in the longitudinal direction L, and the plurality of recesses 32 are adjacent to the ridges in the width direction W (that is, It is positioned between adjacent ridges in the width direction W) and is formed as a plurality of grooves extending continuously in the longitudinal direction L. Since the nonwoven fabric 10 has such a ridge-and-groove structure, it has excellent cushioning properties in the thickness direction T, can exhibit a good touch feeling, and is capable of absorbing excrement in the longitudinal direction L in which the ridges and grooves extend. can be diffused along

The second surface 24 of the nonwoven fabric 10 has a substantially flat surface structure. The nonwoven fabric 10 can ensure a wider contact area with the absorbent body 3 arranged on the non-skin-facing side of the topsheet 2 , so that the liquid excrement that permeates the topsheet 2 can be efficiently transported to the absorbent body 3 . You can definitely move it. In the present invention, the second surface 24 of the nonwoven fabric 10 is not limited to the surface structure as described above. For example, the second surface 24 of the nonwoven fabric 10 has a surface structure in which portions corresponding to the convex portions 30 on the first surface 22 side and the thickness direction T protrude from the first surface 22 toward the second surface 24. may be As another example, the second surface 24 of the nonwoven fabric 10 has a surface structure in which portions corresponding to the convex portions 30 on the first surface 22 side and the thickness direction T are depressed in the direction from the second surface 24 toward the first surface. may have.

The nonwoven fabric 10 may have a compressed portion 34 as shown in FIG. The compressed portions 34 are intermittently arranged along the longitudinal direction L in the recess 32 . The compressed portions 34 may be arranged at equal intervals in the longitudinal direction L in the concave portion 32, or may be arranged at irregular intervals. The recesses 32 adjacent to each other in the width direction W may be located at the same position in the longitudinal direction L, or at different positions. The nonwoven fabric 10 shown in FIG. 2 has compressed portions 34 arranged in a checkerboard pattern in the recesses 32 . The compressed portion 34 is formed by sandwiching from above the first fiber layer 26 and below the second fiber layer 28 in the thickness direction T, and joins the first fiber layer 26 and the second fiber layer 28 .

The basis weights of the first fiber layer 26 and the second fiber layer 28 are generally uniform in the surface direction. The fiber density of the protrusions 30 is lower than the fiber density of the recesses 32 . The fiber density of the recessed portion 32 is lower than the fiber density of the compressed portion 34 . Either the basis weight of the first fiber layer 26 or the basis weight of the second fiber layer 28 may be higher or may be the same.

The first fiber layer 26 is liquid permeable and has a basis weight of, for example, 6 to 200 g/m ² . The thermoplastic resin fibers contained in the first fiber layer 26 are not particularly limited as long as they are fibers made of thermoplastic resin. Examples include polyethylene (PE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA). Olefin resins such as; polyester resins such as polyethylene terephthalate (PET) and polylactic acid (PLA); and known resins such as polyamide resins such as 6-nylon, and these resins may be used alone. , two or more resins may be used in combination. The structure of such thermoplastic resin fibers is not particularly limited, and examples include composite fibers such as core-sheath type fibers such as PET/PE, side-by-side type fibers, and island/sea type fibers; fibers; modified cross-section fibers such as flat, Y-shaped, and C-shaped fibers, and fibers having these structures may be used alone or in combination of two or more types. The fiber fineness is, for example, 1 to 20 dtex.

The second fiber layer 28 is liquid-permeable and has a basis weight of, for example, 6 to 200 g/m ² . The water-absorbent fibers contained in the second fiber layer 28 include, for example, natural cellulosic fibers such as pulp, cotton, and hemp; regenerated cellulosic fibers such as rayon, lyocell, and cupra; One type of fiber may be used alone, or two or more types of fibers may be used in combination. The thermoplastic resin fibers contained in the second fiber layer 28 can be selected from the thermoplastic resin fibers exemplified for the first fiber layer 26, and may be the same as or different from the first fiber layer 26. good. The fineness of the thermoplastic resin fibers contained in the second fiber layer 28 is, for example, 1 to 20 dtex.

The fiber diameter of the thermoplastic resin fibers contained in the second fiber layer 28 may differ from the fiber diameter of the thermoplastic resin fibers contained in the first fiber layer 26. The fiber diameter of the thermoplastic resin fibers contained in the second fiber layer 28 may be smaller than the fiber diameter of the thermoplastic resin fibers contained in the first fiber layer 26 . Thermoplastic resin fibers having a smaller fiber diameter are easily thermally bonded to each other. Therefore, when an air-through nonwoven fabric is formed using thermoplastic resin fibers having a smaller fiber diameter, the nonwoven fabric is less deformable because it has more heat-bonded joints.

The content of the water-absorbing fibers in the second fiber layer 28 can be obtained as follows. (1) After cutting out a sample of a target region from a nonwoven fabric dried in advance at 105° C. for 1 hour, the initial mass (g) of the sample is measured. (2) The sample is immersed in 70% sulfuric acid for 1 hour to dissolve the absorbent fibers. (3) The sample after immersion in sulfuric acid is washed with about 6 liters of water while being sucked on a Buchner funnel, and then washed with about 1 liter of pure water. (4) After drying the washed sample at 105° C. for 2 hours, the post-treatment mass (g) of the sample is measured. (5) By subtracting the post-treatment mass of the sample from the initial mass of the sample, the water-absorbent fiber content mass (g) in the sample is calculated, and the obtained water-absorbent fiber content mass is calculated per unit plan view area. By converting to the mass of, the content of the water-absorbent fiber can be obtained.

The first fiber layer 26 and the second fiber layer 28 can be joined by a gas blowing method. Specifically, it is as follows. A first fibrous web made of thermoplastic resin fibers for the first fibrous layer 26 and a second fibrous web containing water-absorbing fibers and thermoplastic resin fibers for the second fibrous layer 28 are laminated to form a laminated fibrous web. . Next, while conveying the laminated fiber web, a gas (for example, air) having a predetermined temperature and a predetermined pressure is blown against the surface of the laminated fiber web to entangle the fibers in each fiber web and between each fiber web. . Next, the laminated fiber web is conveyed to an air-through type heating device, and the fibers in each fiber web and between each fiber web are fused with the thermoplastic resin fibers in the heating device, thereby converting the thermoplastic resin fibers into It is possible to obtain a non-woven fabric in which the first fiber layer 26 composed of water-absorbent fibers and the second fiber layer 28 containing the water-absorbent fibers and the thermoplastic resin fibers are joined together. The second fibrous layer 28 comprises thermoplastic fibers with thermally bonded joints and absorbent fibers that are not thermally bonded.

The method of imparting the uneven structure as described above to the nonwoven fabric in which the first fiber layer 26 and the second fiber layer 28 are bonded is basically carried out according to the method of manufacturing a composite sheet described in Japanese Patent No. 6139039. can be done. Specifically, a nonwoven fabric obtained by bonding a first fiber layer 26 made of thermoplastic resin fibers and a second fiber layer 28 containing water-absorbing fibers and thermoplastic resin fibers is sandwiched between a pair of gear processing rolls to locally A plurality of concave portions 32 can be formed and the nonwoven fabric 10 can be obtained by pressing the nonwoven fabric.

The nonwoven fabric 10 comprising the first fiber layer 26, the second fiber layer 28, and the third fiber layer 36 can be formed by the following method. A third fibrous web made of thermoplastic resin fibers for the third fibrous layer 36 is overlapped with the first fibrous web and the second fibrous web to form a laminated fibrous web. As described above, the laminated fiber web is transported by blowing a gas (for example, air) having a predetermined temperature and a predetermined pressure onto the surface of the laminated fiber web, thereby separating the fibers in each fiber web and between each fiber web. confound the Next, the laminated fiber web is conveyed to an air-through type heating device, and the fibers in each fiber web and between each fiber web are fused with thermoplastic resin fibers in the heating device to form the first fiber layer 26, A nonwoven fabric in which the second fiber layer 28 and the third fiber layer 36 are joined can be obtained. Furthermore, the nonwoven fabric 10 can be obtained by forming a plurality of recesses 32 by the above-described gear processing.

Next, the characteristics of the nonwoven fabric 10 that receives a load in the thickness direction T will be described. The load in the thickness direction T on the nonwoven fabric 10 acts mainly on the protrusions 30 protruding in the thickness direction T. As shown in FIG. The convex portion 30 is compressed in the thickness direction T by the load, and as the load increases, the difference d between the highest portion 31 of the convex portion 30 and the deepest portion 33 of the concave portion 32 gradually decreases. In the nonwoven fabric 10 to which no load is applied in the thickness direction T, the thickness of the first fiber layer 26 in the convex portions 30 is Tc1, and the thickness of the first fiber layer 26 in the concave portions 32 is Td1. In the nonwoven fabric 10 to which a load of 2.9 kPa (30 gf/cm ² ) is applied in the thickness direction T, the thickness of the first fiber layer 26 in the protrusions 30 is Tc2, and the thickness of the first fiber layer 26 in the recesses 32 is Td2. and The load of 2.9 kPa (30 gf/cm ² ) is assumed to be applied to the sanitary napkin when worn by the wearer.

As described above, the nonwoven fabric 10 has the recesses 32 formed by gear processing or the like, so the recesses 32 are more compressed in the thickness direction T than the projections 30 . Therefore, in the nonwoven fabric 10 to which no load is applied in the thickness direction T, the thickness Tc1 of the first fiber layer 26 in the protrusions 30 is thicker than the thickness Td1 of the first fiber layer 26 in the recesses 32 . That is, the nonwoven fabric 10 to which no load is applied in the thickness direction T satisfies the relational expression of Tc1>Td1.

When a load of 2.9 kPa (30 gf/cm ² ) in the thickness direction T is applied to the nonwoven fabric 10, the nonwoven fabric 10 satisfies the relational expression of (Tc2/Tc1)<(Td2/Td1). That is, in the nonwoven fabric 10 to which a load of 2.9 kPa is applied in the thickness direction T, the thickness of the first fiber layer 26 in the protrusions 30 is less than that in the recesses 32. high percentage of In the case of the nonwoven fabric 10 having the pressed portions 34 , the thickness of the first fiber layer 26 in the recessed portions 32 is the thickness measured in the recessed portions 32 other than the pressed portions 34 .

In the nonwoven fabric 10 to which a load of 2.9 kPa is applied in the thickness direction T, the thickness Tc2 of the first fiber layer 26 in the convex portions 30 is preferably thinner than the thickness Td2 of the first fiber layer 26 in the concave portions 32. That is, the nonwoven fabric 10 preferably satisfies the relational expression Tc2<Td2. As described above, the nonwoven fabric 10 to which no load is applied in the thickness direction T satisfies the relational expression of Tc1>Td1, but by receiving the load in the thickness direction T, the first fiber layer 26 in the convex portion 30 is Compressed. As a result, in the nonwoven fabric 10 to which a load of 2.9 kPa was applied in the thickness direction T, the nonwoven fabric 10 satisfies the relational expression of Tc2<Td2. In the case of the nonwoven fabric 10 having the pressed portions 34 , the thickness of the first fiber layer 26 in the recessed portions 32 is the thickness measured in the recessed portions 32 other than the pressed portions 34 .

In the nonwoven fabric 10 to which a load of 2.9 kPa is applied in the thickness direction T, the deepest part 33 of the concave part 32 is located at a position recessed from the highest part 31 of the convex part 30 toward the second surface 24 from the first surface 22. is preferred. By receiving the load in the thickness direction T, the convex portion 30 is compressed, and as the load increases, the difference between the highest portion 31 of the convex portion 30 and the deepest portion 33 of the concave portion 32 decreases. In the nonwoven fabric 10, when the load in the thickness direction T is 2.9 kPa or less, the deepest portions 33 of the concave portions 32 are located at positions recessed from the highest portions 31 of the convex portions 30 toward the second surface 24 from the first surface 22. Holds shape.

(Measuring method)
The basis weight, thickness, fiber density and fineness of the nonwoven fabric in the above embodiment are measured by the following methods.
(1) Basis weight of non-woven fabric: A non-woven fabric is cut into a size of 5 cm x 5 cm as a sample, and the mass is measured after drying in an atmosphere of 100°C or higher. The basis weight of the sample is calculated by dividing the measured mass by the area of the sample. Let the value which averaged the basis weight of ten samples be the basis weight of a nonwoven fabric.
(2) Thickness of non-woven fabric: Using a thickness gauge (model FS-60DS manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) equipped with a 15 cm ² stylus, a measurement load of 3 gf/cm ² (0.3 kPa) Measure the thickness of the nonwoven fabric under conditions. The thickness of one sample is measured at three locations, and the average value of the thicknesses at the three locations is taken as the thickness of the nonwoven fabric.
(3) Fiber density of nonwoven fabric: The fiber density of the nonwoven fabric is calculated by dividing the weight of the nonwoven fabric obtained by the above method by the thickness of the nonwoven fabric obtained by the above method.
(4) Fiber fineness: Fiber fineness is determined by measuring the cross-sectional area of the fiber by observing the cross-sectional shape of the target fiber under magnification using a scanning electron microscope. Specific gravities of fiber constituents).

(Action and effect)
When the nonwoven fabric 10 is worn, the protrusions 30 are in contact with the wearer's skin, and the recesses 32 are separated from the wearer's skin by a maximum height from the deepest part 33 to the highest part 31. . When liquid excrement such as menstrual blood is supplied from the wearer, the first fiber layer 26 (thermoplastic resin fiber) of the convex portion 30 receives the excrement, and the non-skin-facing surface (the second Excrement is quickly transferred to the absorbent body 3 located on the side of the second surface 24).

From the wearer, in addition to liquid excrement, moisture such as sweat is discharged from the skin. The water is in the form of droplets or vapor, unlike excrement. Since the convex portion 30 has a thick first fiber layer 26 made of thermoplastic resin fibers, the water mainly moves through the first fiber layer 26 in the thickness direction T, unlike excrement. It reaches the recesses 32 directly from the wearer's skin or along the first surface 22 . Since the thickness of the first fiber layer 26 of the concave portion 32 is thinner than the thickness of the first fiber layer 26 of the convex portion 30 , the distance from the first surface 22 of the concave portion 32 to the second fiber layer 28 is the same as that of the convex portion 30 . It is shorter than the distance from the first surface 22 to the second fiber layer 28 , and moisture such as sweat easily reaches the second fiber layer 28 in the recess 32 . Therefore, in the nonwoven fabric 10, the water-absorbing fibers contained in the second fiber layer 28 of the concave portions 32 easily absorb moisture such as sweat discharged from the wearer's skin. Furthermore, the moisture reaching the second fiber layer 28 is transferred to the absorbent body 3 located on the non-skin facing surface (second surface 24 ) side by the thermoplastic resin fibers contained in the second fiber layer 28 .

When the nonwoven fabric 10 receives a load in the thickness direction T, i.e., when it receives body pressure of the wearer, etc., the protrusions 30 projecting in the thickness direction T may cause contact between the wearer's skin and the wearer's underwear. A load acts mainly on the convex portion 30 so as to be sandwiched between the two. Therefore, the convex portion 30 is compressed in the thickness direction T by the load, and as the load in the thickness direction T increases, the difference d between the highest portion 31 of the convex portion 30 and the deepest portion 33 of the concave portion 32 decreases.

The nonwoven fabric 10 satisfies the relational expression of (Tc2/Tc1)<(Td2/Td1) when a load of 2.9 kPa is applied in the thickness direction T. That is, in the nonwoven fabric 10 , the thickness of the first fiber layer 26 in the protrusions 30 decreases at a higher rate than in the first fiber layers 26 in the recesses 32 . Therefore, when the nonwoven fabric 10 receives the body pressure of the wearer, the distance from the first surface 22 to the second fiber layer 28 is shorter even in the protrusions 30 than before the load in the thickness direction T is applied. As a result, moisture such as perspiration discharged from the wearer's skin can easily reach the second fiber layer 28 through the first fiber layer 26 even in the protrusions 30 . Part of the moisture is absorbed by the water-absorbent fibers contained in the second fiber layer 28, and the other part is absorbed by the thermoplastic resin fibers contained in the second fiber layer 28, and the non-skin-facing surface (second surface 24) side. to the absorbent body 3 located at . Therefore, when the nonwoven fabric 10 receives the wearer's body pressure or the like, the water-absorbent fibers can absorb moisture such as sweat discharged from the wearer's skin even in the protrusions 30 .

Even when the second fiber layer 28 absorbs water such as sweat of the wearer and excrement excreted by the wearer as described above, the water-absorbing fibers contained in the second fiber layer 28 are used as the projections 30 . , the first fiber layer 26 is interposed between the wearer's skin and the second fiber layer 28, and in the concave portion 32, the water-absorbing fibers contained in the second fiber layer 28 are projected at a position away from the wearer's skin. The first fiber layer 26 of portion 30 holds. Therefore, the nonwoven fabric 10 prevents the first surface 22 from sticking to the wearer's skin.

As described above, the nonwoven fabric 10 can provide the nonwoven fabric 10 for the liquid-permeable sheet of the absorbent article 1 that is excellent in water absorption and suppresses sticking to the wearer's skin.

In a preferred embodiment, in the protrusions 30 of the nonwoven fabric 10, the basis weights of the first fiber layer 26 and the second fiber layer 28 are uniform in the surface direction, and the thickness of the first fiber layer 26 in the recesses 32 is the same as in the protrusions 30. The thickness of the first fiber layer 26 is thinner than the thickness of the first fiber layer 26 , that is, the thickness of the first fiber layer 26 in the convex portion 30 is thicker than the thickness of the first fiber layer 26 in the concave portion 32 . In this case, the first fiber layer 26 of the convex portion 30 has a lower fiber density than the first fiber layer 26 of the concave portion 32, and the first fiber layer 26 deforms more in the thickness direction T. It's easy to do. Moreover, when the convex portion 30 receives a load in the thickness direction T, the load in the thickness direction T acts from the first surface 22 and the second surface 24, so that the first fiber layer 26 of the convex portion 30 , the thickness of the concave portion 32 is more likely to be reduced than that of the first fiber layer 26 . On the other hand, in the recesses 32 , the basis weights of the first fiber layer 26 and the second fiber layer 28 are uniform in the plane direction, and the thickness of the first fiber layer 26 in the recesses 32 is the same as the thickness of the first fiber layer 26 in the protrusions 30 . Since the first fiber layer 26 is thinner than the thickness, the fiber density of the first fiber layer 26 in the concave portion 32 is high, and the first fiber layer 26 is less likely to deform in the thickness direction T. Furthermore, in the nonwoven fabric 10 , as long as the protrusions 30 protrude from the recesses 32 in the thickness direction T on the first surface 22 , the load in the thickness direction T hardly acts on the recesses 32 . Therefore, even when a load is applied in the thickness direction T of the nonwoven fabric 10 , the thickness of the first fiber layer 26 in the concave portions 32 is less likely to change than the thickness of the first fiber layer 26 in the convex portions 30 .

In a preferred embodiment, the thickness Tc1 of the first fiber layer 26 in the protrusions 30 is greater than the thickness Td1 of the first fiber layer 26 in the recesses 32 when no load is applied in the thickness direction T to the nonwoven fabric 10 . That is, the nonwoven fabric 10 to which no load is applied in the thickness direction T satisfies the relational expression of Tc1>Td1. In this case, when the load in the thickness direction T is applied to the nonwoven fabric 10, the thickness of the first fiber layer 26 in the protrusions 30 decreases at a higher rate than the thickness of the first fiber layer 26 in the recesses 32. , the difference between the thickness of the first fiber layer 26 in the convex portion 30 and the thickness of the first fiber layer 26 in the concave portion 32 is reduced. As a result, in the nonwoven fabric 10 to which a load of 2.9 kPa is applied in the thickness direction T, the nonwoven fabric 10 satisfies the relational expression of Tc2<Td2. Thus, in the nonwoven fabric 10, when the load in the thickness direction T is 2.9 kPa, the thickness of the first fiber layer 26 in the convex portions 30 is reduced, and the thickness of the first fiber layer 26 in the convex portions 30 is reduced to that of the concave portions. Since the thickness of the first fiber layer 26 at 32 is thinner than the thickness of the first fiber layer 26 , the distance from the first surface 22 to the second fiber layer 28 at the convex portion 30 is also reduced. Therefore, when the nonwoven fabric 10 receives the body pressure of the wearer, the water-absorbent fibers can absorb moisture such as sweat discharged from the wearer's skin even in the protrusions 30 .

When the nonwoven fabric 10 receives the wearer's body pressure or the like, the convex portions 30 deform in the thickness direction T while receiving the above load. The convex portion 30 is compressed in the thickness direction T by the load, and the difference d between the highest portion 31 of the convex portion 30 and the deepest portion 33 of the concave portion 32 is reduced. When a load of 2.9 kPa is applied to the nonwoven fabric 10 in the thickness direction T, in a preferred embodiment, the nonwoven fabric 10 is such that the deepest portions 33 of the plurality of concave portions 32 are located closer to the second surface than the highest portions 31 of the plurality of convex portions 30 . It maintains a shape that is recessed towards 24 . That is, when the load in the thickness direction T of the nonwoven fabric 10 is 2.9 kPa or less, the deepest part 33 of the concave part 32 is recessed from the first surface 22 toward the second surface 24 from the highest part 31 of the convex part 30. holds the shape in . In this case, the nonwoven fabric 10 suppresses sticking to the wearer's skin by preventing the concave portions 32 from coming into contact with the wearer's skin when subjected to body pressure or the like of the wearer.

In a preferred embodiment, the second fiber layer 28 of the nonwoven fabric 10 contains 30% to 70% by mass of absorbent fibers. In this case, the concave portions 32 easily absorb moisture such as sweat, and the convex portions 30 also shorten the distance from the first surface 22 to the second fiber layer 28 when the nonwoven fabric 10 receives a load in the thickness direction T. Therefore, it is easy to absorb moisture such as sweat. Since the nonwoven fabric 10 contains thermoplastic resin fibers in the second fiber layer 28, the excrement received by the first fiber layer 26 in the convex portion 30 is quickly transferred to the absorbent body 3 arranged on the non-skin facing side. , the recesses 32 receive excrement that has reached along the first surface 22 and transfer it to the absorbent body 3 on the non-skin facing surface side. Therefore, since the nonwoven fabric 10 contains 30% to 70% by mass of water-absorbing fibers and thermoplastic resin fibers, the water-absorbing fibers absorb moisture such as sweat discharged from the wearer's skin, and the wearer's body is worn. Excrement excreted by a person is transferred to the non-skin facing side by the thermoplastic resin fibers.

In a preferred embodiment, the fiber diameter of the thermoplastic resin fibers of the second fiber layer 28 is smaller than the fiber diameter of the thermoplastic resin fibers of the first fiber layer 26. In this case, since the second fiber layer 28 has a smaller fiber diameter, the thermoplastic resin fibers are more likely to be thermally bonded to each other. many. That is, since the second fiber layer 28 has many joints, it is difficult to deform. On the other hand, since the first fiber layer 26 has a larger fiber diameter, it is more difficult to thermally bond than the thermoplastic resin fibers of the second fiber layer 28, and since there are few bonded portions where the intersections of the thermoplastic resin fibers are thermally bonded, deformation does not occur. Cheap. Therefore, in the nonwoven fabric 10, the easily deformable first fiber layer 26 is supported by the less deformable second fiber layer 28 from the second surface 24 side at the protrusions 30, thereby applying a load in the thickness direction T. In this case, the distance from the first surface 22 to the second fiber layer 28 tends to be shortened in the convex portion 30 as well by reducing the thickness of the convex portion 30 . As a result, when the nonwoven fabric 10 receives the wearer's body pressure or the like because the fiber diameter of the thermoplastic resin fibers of the second fiber layer 28 is smaller than the fiber diameter of the thermoplastic resin fibers of the first fiber layer 26, , the water-absorbing fibers easily absorb moisture such as sweat discharged from the wearer's skin.

In a preferred embodiment, the nonwoven fabric 10 has a third fiber layer 36 on the second surface 24 side. In this case, the first fiber layer 26 is supported by the second fiber layer 28 and the third fiber layer 36 at the convex portion 30 from the second surface 24 side when the body pressure of the wearer is received. As a result, when a load is applied in the thickness direction T to the nonwoven fabric 10, the load is likely to be applied to the first fiber layer 26 in the protrusions 30, so the thickness of the first fiber layer 26 in the protrusions 30 is likely to decrease. . Therefore, when the nonwoven fabric 10 receives the wearer's body pressure or the like, the thickness of the first fiber layer 26 in the protrusions 30 is reduced, so that the protrusions 30 also extend from the first surface 22 to the second fiber layer 28 . As the distance becomes shorter, the absorbent fibers can absorb moisture such as perspiration discharged from the wearer's skin.

In a preferred embodiment, the nonwoven fabric 10 has part of the absorbent fibers exposed from the first surface 22 . In this case, when the nonwoven fabric 2 is used for the liquid-permeable sheet of the absorbent article 1, it is discharged from the wearer's skin through part of the water-absorbent fibers exposed from the skin-facing surface (first surface 22). Since moisture such as perspiration can be easily transferred to the second fiber layer 28, it is excellent in water absorption.

(Modification)
The type and application of the absorbent article are not particularly limited, and examples thereof include panty liners, disposable diapers (tape type, pants type), incontinence pads, and sanitary and sanitary products such as sweat absorbent sheets. Humans may be the target, and animals other than humans such as pets may be the target. The liquid to be absorbed by the absorbent article is not particularly limited, and examples thereof include the wearer's liquid excrement and bodily fluids.

The uneven structure having a plurality of protrusions and a plurality of recesses is not limited to a ridge groove structure. For example, a plurality of rows of protrusions extending intermittently in the longitudinal direction and arranged in the width direction, Concavo-convex structure consisting of a plurality of rows of concave portions intermittently extending in the longitudinal direction between adjacent convex portions, a plurality of hemispherical or cylindrical convex portions, and a plurality of concave portions located between adjacent convex portions Concavo-convex structure etc. are mentioned.

As an example of forming the nonwoven fabric 10 comprising the first fibrous layer 26, the second fibrous layer 28, and the third fibrous layer 36, the third fibrous web is laminated with the first fibrous web and the second fibrous web to form a laminated fiber. Although the case of forming a web has been described, the present invention is not limited to this. For example, the nonwoven fabric is composed of the first nonwoven fabric that joins the first fiber layer 26 and the second fiber layer 28 and has a ridged groove structure on the skin facing surface, and the third fiber layer on the non-skin facing surface side of the first nonwoven fabric. and a second nonwoven fabric consisting of 36.

(Example)
A nonwoven fabric corresponding to the above embodiment was produced and evaluated. EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

(1) Sample By the gear processing described above, the first fiber layer made of the thermoplastic resin fiber of the core-sheath type fiber, and the second fiber layer containing rayon as the water absorbing fiber and the thermoplastic resin fiber of the core-sheath type fiber A nonwoven fabric of an example consisting of an air-through nonwoven fabric bonded with was produced. Table 1 shows the detailed configuration of the nonwoven fabrics according to the examples. The nonwoven fabric of the example had a plurality of ridges and a plurality of grooves.

As reference examples, an air-through nonwoven fabric (reference example 1) formed of thermoplastic resin fibers of core-sheath type fibers and a nonwoven fabric made of cotton (reference example 2) were produced. Detailed configurations of the nonwoven fabrics according to Reference Examples 1 and 2 are as shown in Table 1. None of the nonwoven fabrics according to Reference Examples 1 and 2 had ridges and grooves on the surface.

(2) Evaluation method The sticking property of the nonwoven fabric was evaluated by the following method.
(i) A solution of 50 ml of ion-exchanged water and 50 ml of colored water was prepared.
(ii) Silcot (trademark) (manufactured by Unicharm Co., Ltd.) was dripped with 8 g of the above solution while measuring the amount of dripping, and the whole was covered.
(iii) A weight of 30 g/cm ² (size: 50 mm×35 mm) to which artificial leather was adhered was placed on Silcot and left for 30 seconds.
(iv) A sample cut into a size of 60 mm×50 mm was placed on two layers of air-laid nonwoven fabric, and the weight of (iii) was placed on the sample.
(v) After 30 seconds, the weight was lifted and it was visually confirmed whether the sample was stuck to the weight.
The above evaluation was performed with N=10 for each sample.
The weight (iii) was transferred to the filter paper for 30 seconds, and the amount of the solution adhering to the artificial leather of the weight was measured to be 0.036 g (average of N=5).
If the number of samples (N=10) stuck to the weight was 2 or less, it was judged to be acceptable, and if it was 3 or more, it was judged to be unacceptable.

(3) Results The nonwoven fabric according to the example was acceptable because the number of samples attached to the weight was two, and one of the samples dropped from the weight immediately due to its own weight. All of the nonwoven fabrics according to Reference Examples failed because 10 samples adhered to the weight. From the above, it was confirmed that the nonwoven fabric according to this example can suppress sticking to the wearer's skin.

1 Absorbent Article 1A Body Part 1B Flap Part 2 Topsheet 3 Absorbent Body 4 Backsheet 9 Exterior Sheet 10 Nonwoven Fabric 22 First Surface 24 Second Surface 26 First Fiber Layer 28 Second Fiber Layer 30 Convex Part 31 Highest Part 32 Concave Part 33 deepest part 34 compression part

Claims

A nonwoven fabric for a liquid-permeable sheet of an absorbent article comprising a first fiber layer and a second fiber layer in order in the thickness direction,
The first fiber layer is made of thermoplastic resin fibers and has a first surface that is the skin-facing surface of the liquid-permeable sheet,
The second fiber layer contains water-absorbent fibers and thermoplastic resin fibers, and has a second surface that serves as a non-skin facing surface of the liquid-permeable sheet,
a plurality of solid convex portions protruding in a direction from the second surface toward the first surface and a plurality of concave portions recessed in a direction from the first surface toward the second surface on the first surface; has
The thickness of the first fiber layer in the plurality of recesses is thinner than the thickness of the first fiber layer in the plurality of protrusions,
In the nonwoven fabric to which a load is not applied in the thickness direction, the thickness of the first fiber layer in the plurality of protrusions and the thickness of the first fiber layer in the plurality of recesses are Tc1 and Td1, respectively; In the nonwoven fabric to which a load of 2.9 kPa is applied in the thickness direction, the thickness of the first fiber layer in the plurality of protrusions and the thickness of the first fiber layer in the plurality of recesses are Tc2 and Td2, respectively. A nonwoven fabric that satisfies the relational expression of (Tc2/Tc1)<(Td2/Td1) when .
The basis weights of the first fiber layer and the second fiber layer are uniform in the plane direction,
2. In the nonwoven fabric to which a load of 2.9 kPa is applied in the thickness direction, the thickness of the first fiber layer in the plurality of protrusions is thinner than the thickness of the first fiber layer in the plurality of recesses. 1. The nonwoven fabric according to 1.
In the nonwoven fabric to which a load of 2.9 kPa is applied in the thickness direction, the deepest part of the plurality of recesses is a position recessed from the first surface toward the second surface from the highest part of the plurality of protrusions. 3. The nonwoven fabric according to claim 1 or 2.
The nonwoven fabric according to any one of claims 1 to 3, wherein the second fiber layer contains 30% by mass to 70% by mass of the water absorbent fiber.
The fiber diameter of the thermoplastic resin fibers of the second fiber layer is smaller than the fiber diameter of the thermoplastic resin fibers of the first fiber layer,
The nonwoven fabric according to any one of claims 1 to 4, wherein in each of the first fiber layer and the second fiber layer, the intersections of the thermoplastic resin fibers are thermally bonded.
The nonwoven fabric according to any one of claims 1 to 5, comprising a third layer made of thermoplastic resin fibers on the second surface side.
The nonwoven fabric according to any one of claims 1 to 6, wherein part of the water-absorbing fibers are exposed from the first surface.