Nonwoven fabric for absorbent article

Abstract

To provide a nonwoven fabric for absorbent article simultaneously achieving excellent cushioning property and high dry performance of a surface when absorbing liquid.SOLUTION: A nonwoven fabric has a first fiber layer and a second fiber layer stacked in a thickness direction and includes fiber fused parts at intersections between fibers in the respective fiber layers. The first fiber layer has an uneven structure having a plurality of convex parts and bottom parts disposed between adjacent convex parts. Each of the plurality of convex parts has an apex, a wall part supporting the apex, and a hollow part inside. The nonwoven fabric for absorbent article has the second fiber layer on a side where the bottom parts of the first fiber layer exist. The second fiber layer includes thermoplastic fibers and water-absorbing fibers. A mixed layer of the thermoplastic fibers and the water-absorbing fibers enters the hollow part of the first fiber layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a nonwoven fabric for absorbent articles. [Background technology]

[0002] Nonwoven fabrics are used in a variety of applications, such as components of absorbent articles such as diapers and sanitary napkins, and therefore nonwoven fabrics having a variety of structures have been developed. For example, there are nonwoven fabrics having an uneven structure in the thickness direction, in which the convex portions in the uneven structure are hollow (e.g., Patent Document 1), and those having solid, dome-shaped convex portions (e.g., Patent Document 2), etc. There is also a nonwoven fabric having an uneven structure including solid, dome-shaped convex portions, in which the bottom portions, which are the non-skin-facing sides of the convex portions, contain cotton and thermoplastic fibers (e.g., Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-44293 A [Patent Document 2] JP 2014-12913 A [Patent Document 3] JP 2019-69089 A Summary of the Invention [Problem to be solved by the invention]

[0004] The uneven structure as described above has the effect of enhancing the cushioning properties of the nonwoven fabric. For example, when the nonwoven fabric is used as a top sheet of an absorbent article that comes into contact with the skin of a wearer, the absorbent article feels soft to the touch when worn. On the other hand, the absorbency of excreted liquid is an important basic performance of an absorbent article, and the nonwoven fabric is also required to have a dry property that reduces the amount of liquid remaining on the surface. In recent years, there has been an increasing demand for improved cushioning properties and dryness upon liquid absorption in such nonwoven fabrics, and further improvements are being sought in these properties in light of the increasing standards required for comfortable wear of absorbent articles.

[0005] In view of the above, the present invention relates to a nonwoven fabric for absorbent articles which simultaneously has excellent cushioning properties and a high degree of surface dryness when absorbing liquid. [Means for solving the problem]

[0006] The present invention provides a nonwoven fabric for absorbent articles, which has a first fiber layer and a second fiber layer laminated in the thickness direction, each fiber layer including fiber fusion portions at the intersections of fibers, wherein the first fiber layer has an uneven structure including a plurality of protrusions and a bottom portion provided between adjacent protrusions, each of the plurality of protrusions includes an apex and a wall portion supporting the apex and has a hollow portion therein, the second fiber layer being located on the side of the first fiber layer where the bottom portion is located, and the second fiber layer includes thermoplastic fibers and water-absorbent fibers, and a mixed layer of thermoplastic fibers and water-absorbent fibers penetrates into the hollow portion of the first fiber layer. Effect of the Invention

[0007] The nonwoven fabric for absorbent articles of the present invention has excellent cushioning properties and at the same time a high degree of dryness of the surface when absorbing liquid. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a schematic diagram of a preferred embodiment of a nonwoven fabric for absorbent articles according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view illustrating a schematic diagram of another preferred embodiment of the nonwoven fabric for absorbent articles according to the present invention. [Diagram 3] 1 is a plan view showing a specific example of a nonwoven fabric for absorbent articles according to the present embodiment, viewed from one side. [Figure 4] 4 is a cross-sectional view taken along the line R1-R1 of the nonwoven fabric for absorbent articles shown in FIG. 3. [Diagram 5]4 is a cross-sectional view taken along the line R2-R2 of the nonwoven fabric for absorbent articles shown in FIG. 3. [Figure 6] 4 is a cross-sectional view taken along the line R3-R3 of the nonwoven fabric for absorbent articles shown in FIG. 3. FIG. [Figure 7] 4 is a cross-sectional view taken along line R4-R4 of the nonwoven fabric for absorbent articles shown in FIG. 3. [Figure 8] FIG. 1 is an explanatory diagram showing a schematic diagram of a preferred embodiment of the method for manufacturing a nonwoven fabric for absorbent articles according to the present invention, in which (A) shows a pushing process, (B) shows a process for obtaining a rugged nonwoven fabric by a first hot air, (C) shows a process for laminating a second fibrous web onto the rugged nonwoven fabric, and (D) shows a process for integrating the rugged nonwoven fabric and the second fibrous web by a second hot air, thereby forming the second fibrous web into a nonwoven fabric. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 13 is a plan view showing a state in which the support body and the push-in member are combined. [Figure 12] FIG. 4 is a cross-sectional view showing another embodiment of the support. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A preferred embodiment of the nonwoven fabric for absorbent articles according to the present invention will be described below with reference to the drawings. In this specification, the nonwoven fabric for absorbent articles may be simply referred to as a nonwoven fabric. The nonwoven fabric 10 of this embodiment is a so-called thermal bonded nonwoven fabric having fiber fusion parts at the intersections of the fibers. For example, an air-through nonwoven fabric in which the fiber fusion parts are formed by an air-through method can be mentioned. Therefore, the nonwoven fabric 10 contains thermoplastic fibers as its constituent fibers. That is, the first fiber layer M1 and the second fiber layer M2, which constitute the nonwoven fabric 10, described below, contain thermoplastic fibers as their constituent fibers, and are nonwoven fabrics in which the fiber fusion parts are formed. The first fiber layer M1 and the second fiber layer M2 are integrated by the fiber fusion parts at the intersections of the fibers of each other.

[0010] The nonwoven fabric 10 of this embodiment has a first fiber layer M1 and a second fiber layer M2 laminated in the thickness direction Z as shown in FIG. 1. The nonwoven fabric 10 has a front and back surface, i.e., one side 10T and the other side 10B, with the first fiber layer M1 arranged on the one side 10T and the second fiber layer M2 arranged on the other side 10B. In the nonwoven fabric 10, for example, the one side 10T can be used as the surface. For example, when the nonwoven fabric 10 is used as a member closer to the skin than the absorbent body of an absorbent article, such as a top sheet, the one side 10T can be used as the skin side. In this case, the first fiber layer M1 is also referred to as the upper layer, and the second fiber layer M2 is also referred to as the lower layer. The one side 10T and the other side 10B refer to the front and back surfaces of the entire nonwoven fabric 10, and also refer to the front and back surfaces of the first fiber layer M1 and the second fiber layer M2. The thickness direction Z of the nonwoven fabric 10 also means the thickness direction Z of each of the first fiber layer M1 and the second fiber layer M2.

[0011] The first fiber layer M1 has a plurality of protruding portions 1 protruding on one surface side 10T and a bottom portion 2 provided between adjacent protruding portions 1, 1. This allows the first fiber layer M1 to have an uneven structure in the thickness direction Z. The protruding portions 1 are three-dimensional fiber layers standing in the thickness direction Z of the first fiber layer M1, and are located higher on the one surface side 10T than the bottom portion 2. Each of the plurality of protruding portions 1 has an apex 1A and a wall portion 1B supporting the apex 1A. The bottom portion 2 of the first fiber layer M1 is located at the bottom of a recess recessed on the other surface side 10B between the protruding portions 1, 1, and is adjacent to the second fiber layer M2.

[0012] The outer shape of one surface side 10T of the top portion 1A may be a flat surface or a curved surface. From the viewpoint of making the touch softer when used as the skin contact surface that comes into contact with the skin of the wearer, it is preferable that one surface side 10T of the top portion 1A is a dome-shaped curved surface.

[0013] The fibers of the wall 1B are preferably oriented longitudinally with respect to the planar direction of the other side 10B of the nonwoven fabric 10 (second fiber layer M2). The planar direction of the nonwoven fabric 10 here means the direction along a plane (such as a flat base) that contacts the surface of the other side 10B of the nonwoven fabric 10 (second fiber layer M2). The longitudinal orientation of the fibers enhances the support force of the wall portion 1B in the thickness direction relative to the top portion 1A and the second fiber layer M2, and makes it easier for the thickness of the protrusions 1 of the nonwoven fabric 10 to be maintained even under load. As a result, the nonwoven fabric 10 including the first fiber layer M1 and the second fiber layer M2 is more likely to retain its thickness, and, together with the elasticity due to the fiber structure of the fiber layers, has excellent cushioning properties. That is, the nonwoven fabric 10 has excellent softness when touching the skin. Furthermore, when the nonwoven fabric 10 is used as a member on the skin side of the absorbent body in an absorbent article, such as a top sheet, the action of permeation of bodily fluids is more likely to be sustained even under load, and the return of liquid from the absorbent body to the skin side (wetback) is suppressed.

[0014] The longitudinal orientation of the fibers in the wall portion 1B means that many fibers are aligned along the thickness direction Z of the first fiber layer M1, and that the longitudinal orientation ratio obtained by the measurement method described below is 60% or more. From the viewpoint of further enhancing the above-mentioned effect, 61% or more is preferable, and 62% or more is more preferable. There is no particular upper limit to the longitudinal orientation ratio, but from the viewpoint of creating intersections between oriented fibers to form fusion points and forming columns between the fibers to form a structure that can withstand force, it is preferable that the longitudinal orientation ratio is 90% or less, more preferably 85% or less, and even more preferably 80% or less.

[0015] (Method of measuring longitudinal orientation rate of fibers in wall portion 1B) As shown in FIG. 1, the wall portion 1B is measured in the following procedure. That is, the fiber layer cross section of the wall portion 1B defined in the cross section in the thickness direction of the nonwoven fabric 10, including the convex portion 1 of the first fiber layer M1 and the second fiber layer M2, is observed at 35 times magnification with a scanning electron microscope (SEM). A square line with a side of 500 μm is added to the observed image as a reference line. Each side (reference line) of the square is defined as a side perpendicular to the thickness direction and the planar direction in the cross section of the nonwoven fabric 10. The total number of fibers passing through the reference line consisting of each side of the square is counted. The fibers passing through the square reference line perpendicular to the planar direction of the nonwoven fabric 10 are defined as the "number of horizontal fibers", and the fibers passing through the square reference line perpendicular to the thickness direction of the nonwoven fabric 10 are defined as the "number of vertical fibers". The longitudinal orientation rate is calculated as (number of vertical fibers) / (number of horizontal fibers+number of vertical fibers)×100=longitudinal orientation rate (%). Three points are measured for each, and the average is taken as the value of the longitudinal orientation rate. The planar direction in the cross section of the nonwoven fabric 10 corresponds to a straight line L tangent to the surface of the other side 10B of the second fiber layer M2 shown in Figure 1. The thickness direction corresponds to a direction Z perpendicular to the straight line L.

[0016] In the above-mentioned cross section in the thickness direction Z of the nonwoven fabric 10, including the protrusions 1 and the bottoms 2 of the first fiber layer M1, the fiber layer of the wall portion 1B can be divided by the following method. That is, a nonwoven fabric 10 having a cross section in the thickness direction Z including the top 1A and wall 1B of the first fiber layer M1 and the second fiber layer M2 is placed on the base of a microscope VHX6000 (product name, manufactured by Keyence Corporation) with the second fiber layer M2 (other surface side 10B) facing down. Next, a flat plate (e.g., a flat acrylic plate) is placed on the top 1A side (one surface side 10T) of the nonwoven fabric 10, and a pressure of 4.9 mN / cm is applied. 2A load of 10 ...

[0017] Additionally, in the first fiber layer M1, the protrusions 1 have hollow spaces 1C therein. The hollow spaces 1C are spaces that are not substantially filled with the fibers of the nonwoven fabric 10. Specifically, the fiber density determined by the method described below is 10 fibers / mm 2 This means that the fiber density in the hollow portions 1C is less than that in the other surface side 10B. The lower the fiber density in the hollow portions 1C, the better. In the first fiber layer M1, the hollow portions 1C of the projections 1 are open to the side of the second fiber layer M2 on the other surface side 10B.

[0018] (Method of measuring fiber density) The fiber density can be measured by observing the cross section of the nonwoven fabric 10 and using the following method. The nonwoven fabric 10 is cut in the thickness direction so as to pass through the area to be measured (for example, between the wall portions 1B). A scanning electron microscope (JCM-6000Plus (product name) manufactured by JEOL Ltd.) is used to observe the cut surface including the hollow portion 1C under magnification, and the number of fibers within a certain area of ​​the cut surface including the hollow portion 1C is counted. The magnification for the magnified observation is adjusted to a magnification (35x or more and 200x or less) that allows the measurement of approximately 30 to 60 fiber cross sections. Next, a 1mm 2 This is converted into the number of fibers per unit, and the fiber density (fibers / mm 2 The results of the measurements at five locations shall be averaged to determine the fiber density of the sample.

[0019] The hollow portion 1C inside the protrusion 1 further improves the soft feel of the protrusion 1, further enhances the cushioning properties described above, and further improves the feel of the nonwoven fabric 10. Furthermore, when the nonwoven fabric 10 is used as a member on the skin side of the absorbent body, such as a top sheet of an absorbent article, the presence of the hollow portion 1C cuts off the liquid return path from the absorbent body, improving the prevention of liquid return. In addition, the hollow portion 1C also serves as a primary storage space in the event of excessive excretion, further reducing the amount of liquid remaining on the skin contact side of the top sheet.

[0020] The second fiber layer M2 is disposed on the side where the bottom of the first fiber layer M1 is located. The second fiber layer M2 includes thermoplastic fibers 61 and absorbent fibers 62, and a mixed layer of the thermoplastic fibers 61 and absorbent fibers 62 partially penetrates the inside of the protrusion 1 and enters the hollow portion 1C of the first fiber layer M1. The mixed layer may be present in the entire second fiber layer or in a part of it. Hereinafter, the mixed layer that penetrates the hollow portion 1C is referred to as an intruding mixed layer 5. In FIG. 1, the absorbent fibers 62 are shown thicker and fewer in number than the thermoplastic fibers 61 to emphasize their presence, but the actual state may be different.

[0021] The water-absorbent fiber 62 is a fiber whose material itself is hydrophilic and has the property of being able to retain moisture within the fiber. For example, it is a fiber made of a cellulose material. Specific examples include natural cellulose fiber, regenerated cellulose fiber, refined cellulose fiber, and semi-synthetic cellulose fiber. These can be used alone or in combination of two or more kinds. Such water-absorbent fiber 62 does not have thermoplasticity and has the property of not forming a fused portion with other fibers.

[0022] Examples of natural cellulose fibers include cotton, wood pulp, bamboo, hemp, fruit (palm, banana, etc.) fibers, etc. Among these, cotton is preferred from the viewpoint of formability of the fiber web that is the base material for producing nonwoven fabric. Examples of regenerated cellulose fibers include rayon fibers such as viscose rayon, polynosic, modal, and cuprammonium rayon obtained from a cuprammonium salt solution of cellulose. Refined cellulose fibers include, for example, Lyocell, available commercially as Tencel™ and Veocel™. Examples of the semi-synthetic cellulose fibers include acetate fibers such as triacetate and diacetate. Among the above-mentioned regenerated cellulose fibers, refined cellulose fibers, and semi-synthetic cellulose fibers, rayon and lyocell are preferred from the viewpoint of formability of the fiber web that serves as the base material in the production of nonwoven fabric.

[0023] The thermoplastic fiber 61 is a synthetic fiber whose material itself is hydrophobic, and whose surface contains a hydrophilic surfactant, thereby giving it hydrophilicity. Such thermoplastic fibers can retain water between the fibers by utilizing the capillary phenomenon, but they are unable to retain water inside the fibers. Such thermoplastic fibers can be any fibers that are commonly used as materials for nonwoven fabrics without any particular restrictions. For example, they may be fibers made of a single resin component or composite fibers made of multiple resin components. Composite fibers may have, for example, a core-sheath structure or a side-by-side structure. When using composite fibers containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air blown onto the fiber web in the manufacturing process is preferably equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component. More preferably, the temperature is equal to or higher than the melting point of the low melting point component and 10°C lower than the melting point of the high melting point component, and even more preferably, the temperature is 5°C or higher than the melting point of the low melting point component and 20°C or lower than the melting point of the high melting point component. In terms of elasticity, the more the core of the core-sheath structure composite fibers have, the higher the elasticity. Therefore, it is preferable that the core component is larger in terms of cross-sectional area ratio. A specific example of a composite fiber having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component is a composite fiber having a core-sheath structure in which the sheath is a polyethylene resin (hereinafter also referred to as PE) and the core is a polyethylene terephthalate resin (hereinafter also referred to as PET). Furthermore, in composite fibers with a core-sheath structure, when the resin component of the sheath has a lower glass transition point than the resin component of the core (hereinafter referred to as a low-glass transition point resin component; for example, the resin component of the core is PET and the resin component of the sheath is PE), the thickness recovery of the nonwoven fabric can be further improved by reducing the mass ratio of the low-glass transition point resin component.

[0024] The nonwoven fabric 10 has a further improved cushioning and softness due to the presence of the aforementioned hollow portion 1C and the intrusion mixed layer 5 in the hollow portion 1C. In the hollow portion 1C, the absorbent fibers 62 constituting the intrusion mixed layer 5 are present without forming fusion parts with other fibers. Therefore, at the bottom side of the hollow portion 1C, which softens the touch of the protrusion 1, the intrusion mixed layer 5 containing the absorbent fibers 62 forms an elastic cushion layer with reduced rigidity due to the fusion parts. As a result, the thickness is easily maintained when the top 1A of the protrusion 1 is touched, and a reassuring thickness can be felt. While the protrusion 1 deforms and sinks with stronger pressure, at the further sinking stage, the presence of the intrusion mixed layer 5, especially the presence of the absorbent fibers 62 that do not form fusion parts, gives the protrusion 1 a soft elasticity. In addition, due to the presence of the intrusion mixed layer 5, the protrusion 1 is less likely to sink to the bottom 2, and a reassuring cushioning feeling can be obtained as a touch to the skin. As a result, when the nonwoven fabric 10 is touched from one surface side 10T, a unique multi-stage cushioning effect is exhibited, increasing the softness. Furthermore, it is preferable that the wall 1B constituting the protrusion 1 has a longitudinal fiber orientation, so that the thickness of the protrusion 1 is likely to remain even if it is repeatedly pressed outward, and it is difficult to wear down. In addition, in the second fiber layer M2, the water-absorbent fiber 62 is likely to be contained in the three-dimensional fiber network formed by the fiber fusion parts between the thermoplastic fibers. Therefore, even if the water-absorbent fiber 62 absorbs water and swells, the layer structure of the second fiber layer M2 is likely to be maintained, it is difficult to wear down, and it is easy to increase the elasticity. In particular, the penetrating mixed layer 5 increases the shape retention of the protrusion 1 of the first fiber layer M1 by the above action, and gives it soft elasticity accompanied by water absorption and swelling. As a result, the nonwoven fabric 10 is likely to repeatedly exhibit the aforementioned multi-stage unique cushioning property.

[0025] In addition, the nonwoven fabric 10 has high liquid absorbency because the absorbent fibers 62 in the second fiber layer M2 easily absorb liquid from the protruding portion 1 of the first fiber layer M1. Moreover, the second fiber layer M2 covered with the first fiber layer M1 imparts liquid absorbency to the nonwoven fabric 10 without being exposed to the one surface side 10T. This reduces the amount of liquid remaining in the first fiber layer M1. In addition, the liquid-absorbing force of the absorbent fibers 62 suppresses the return of liquid from the second fiber layer M2 to the first fiber layer M1. As a result, the nonwoven fabric 10 has improved dryness on the one surface side 10T and is less sticky. Moreover, the hollow portion 1C has an intrusion mixed layer 5 in a part of the bottom side while leaving the space of the hollow portion 1C on the top side 1A. The absorbent fibers 62 of the intruding mixed layer 5 are located toward the one side 10T, but are covered by the fiber layer of the protrusions 1 and are not exposed to the one side 10T, providing liquid absorbency to the nonwoven fabric 10. The presence of the space of the hollow portion 1C in the protrusions 1 prevents liquid from returning directly from the intruding mixed layer 5 to the top 1A. Furthermore, the vertical orientation of the fibers makes the wall portion 1B less likely to wear out, which makes it more difficult for liquid to return from the second fiber layer M2, which is the lower layer. This improves the dryness of the one side 10T, which is the surface of the nonwoven fabric 10. Moreover, it is preferable that the wall 1B constituting the protrusion 1 has longitudinal fiber orientation, which promotes the liquid to flow down along the longitudinally oriented fibers of the wall 1B and is quickly and swiftly delivered to the second fiber layer M2, particularly to the absorbent fibers 62 of the intruding mixed layer 5. This effect can be maintained by the resistance of the wall 1B to settling due to the longitudinal fiber orientation.

[0026] Regarding such a nonwoven fabric 10, the presence of the second fiber layer M2 containing the absorbent fiber 62, particularly the intrusion mixed layer 5, can provide the following effect with regard to the liquid absorbency in an absorbent article. That is, when one surface side 10T of the nonwoven fabric 10 is the skin-facing side and is used as a member closer to the skin than the absorbent body, such as a top sheet of an absorbent article, liquid can be quickly drawn away from the skin and drawn in one direction to the other surface side 10B, and held without being allowed to return. In an absorbent article, the nonwoven fabric 10 arranged as a skin-facing member absorbs liquid in the second fiber layer M2 on the bottom side, and more liquid can be efficiently transferred (drained) to the absorbent body below. This further reduces the amount of liquid remaining on the skin-facing side, improves the dryness of the skin-facing side, and reduces stickiness.

[0027] In this way, the nonwoven fabric 10 simultaneously has excellent cushioning properties and high dryness of the surface (one surface side 10T) when absorbing liquid. In particular, the hollow portions 1C described above prevent the second fiber layer M2, which has absorbed liquid, from returning directly to the surface of the nonwoven fabric 10, so that the surface remains highly dry when absorbing liquid, even if the nonwoven fabric 10 has high cushioning properties accompanied by deformation. Furthermore, when the fibers of the wall portions 1B are vertically oriented, the vertical orientation promotes the action of the hollow portions 1C described above.

[0028] In the nonwoven fabric 10, the ratio (H2 / H1) of the thickness H2 of the intrusive mixed layer 5 to the thickness H1 of the first fiber layer M1 (thickness of the convex portion 1) is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.15 or more, in order to further enhance the above-mentioned effect. The ratio (H2 / H1) of the thickness H2 of the intruding mixed layer 5 to the thickness H1 of the first fiber layer M1 (thickness of the protrusion 1) is preferably 0.9 or less, more preferably 0.8 or less, and even more preferably 0.7 or less, from the viewpoint of enhancing the liquid return suppression ability. The thickness H1 of the first fiber layer M1 refers to the height in the thickness direction Z from the surface of one side 10T of the top 1A to the boundary between the base side of the wall 1B and the second fiber layer M2. The thickness H2 of the intrusive mixed layer 5 refers to the height in the thickness direction Z from the boundary between the base 1D of the wall 1B and the second fiber layer M2 to the point where the intrusive mixed layer 5 penetrates the most into the one side 10T in the hollow 1C of the convex portion 1. These values ​​are 4.9 mN / cm 2 With this load applied, the process can be carried out in the same manner as in the above-mentioned method for dividing the fiber layer of the wall portion 1B.

[0029] The ratio of the number of absorbent fibers 62 to the constituent fibers of the second fiber layer M2 is preferably 8% or more, more preferably 10% or more, and even more preferably 15% or more, from the viewpoint of making the cushioning and absorbency more effective. In addition, when the nonwoven fabric 10 is manufactured, the constituent fibers of the shaped fiber web containing a certain ratio of non-thermally fusible absorbent fibers 62 are easily movable during hot air treatment, and the penetrating mixed layer 5 is easily inserted into the hollow portions 1C of the projections 1. In addition, the proportion of absorbent fibers 62 in the constituent fibers of the second fiber layer M2 is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less, from the viewpoint of maintaining the strength of the nonwoven fabric and improving the formability of the nonwoven fabric by fiber fusion during production. This proportion is preferably met in particular in the mixing inlet 5 . The fiber number ratio means the average fiber number ratio in the second fiber layer M2.

[0030] (Method for measuring the proportion of the number of water-absorbent fibers 62 in the constituent fibers of the second fiber layer M2) In determining the proportion of absorbent fibers 62 in the constituent fibers of the second fiber layer M2 to be measured, the absorbent fibers 62 can be determined by either determining their boundaries from differences in fiber diameter and / or fiber density and calculating the thickness, or by dyeing them with a fiber identification reagent that changes color depending on the type of fiber (for example, BOKENSTAIN II, manufactured by the Boken Quality Evaluation Organization, a general incorporated foundation; this will be used in the following explanation) and visually judging from the color of the dyed fibers to determine whether they are absorbent fibers 62. The second fiber layer M2 to be measured is frozen with liquid nitrogen to fix the state of fiber existence. Next, a razor blade or the like is used to cut perpendicularly to the planar direction of the other surface side 10B so as to form a cross section in the thickness direction Z, to prepare a measurement sample. The cross section of the measurement sample is imaged at 500 times magnification using an electron microscope (JCM-6000Plus (product name), manufactured by JEOL Ltd.). From the image of the cross section, all fibers whose fiber cross sections can be confirmed are visually confirmed, and they are judged to be water-absorbent fibers or other types of fibers other than water-absorbent fibers, and the number of each fiber is counted. The total number of fibers to be counted is 80 or more (since there is a limit to the number of fibers that can be counted from one image, count using many images so that the total number is 80 or more). The ratio of the number of water-absorbent fibers 62 to the total number counted is calculated, and this is taken as the number ratio of water-absorbent fibers 62.

[0031] It is preferable that the fiber diameter (D1) of the thermoplastic fiber 61 contained in the second fiber layer M2 is larger than the fiber diameter (D2) of the absorbent fiber 62. This means that, in the manufacturing process of the nonwoven fabric 10, the thermoplastic fiber 61 is thicker than the absorbent fiber 62 in the fiber web forming the second fiber layer M2, so that the absorbent fiber 62 can easily move between the thermoplastic fibers 61, and more absorbent fiber 62 can be easily arranged in the hollow portion 1C of the protrusion 1. The nonwoven fabric 10 obtained by this process has further improved cushioning properties, liquid absorbency, and thus a dry surface. In addition, the presence of the thermoplastic fiber 61 thicker than the absorbent fiber 62 in the second fiber layer M2 increases the elasticity of the intrusion mixed layer 5, thereby further improving the cushioning properties. From this viewpoint, in the second fiber layer M2, the ratio (D2 / D1) of the fiber diameter (D2) of the water-absorbent fiber 62 to the fiber diameter (D1) of the thermoplastic fiber 61 is preferably 0.2 or more, more preferably 0.3 or more, and even more preferably 0.4 or more. From the viewpoint of improving cushioning properties, the ratio (D2 / D1) is preferably 0.98 or less, more preferably 0.96 or less, and even more preferably 0.94 or less. Furthermore, within the range satisfying the above ratio (D2 / D1), the fiber diameter (D2) of the water-absorbent fiber 62 in the second fiber layer M2 is preferably 8 μm or more, more preferably 10 μm or more, and even more preferably 12 μm or more, from the viewpoint of enhancing cushioning properties. Also, the fiber diameter (D2) of the water-absorbent fiber 62 in the second fiber layer M2 is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, from the viewpoint of enhancing liquid absorbency. In addition, within the range satisfying the above ratio (D2 / D1), the fiber diameter (D1) of the thermoplastic fibers 61 in the second fiber layer M2 is preferably 10 μm or more, more preferably 13 μm or more, and even more preferably 15 μm or more, from the viewpoint of enhancing cushioning properties. In addition, in the second fiber layer M2, the fiber diameter (D1) of the thermoplastic fibers 61 is preferably 60 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less, from the viewpoint of enhancing liquid absorbency. These numerical ranges for fiber diameter are preferably satisfied especially at the mixing inlet 5 . The above fiber diameter means the average fiber diameter in the second fiber layer M2.

[0032] (Method of measuring fiber diameters of water-absorbent fibers 62 and thermoplastic fibers 61 in the second fiber layer M2) The fiber diameter can be measured by observing the cross section of the fiber layer using the following method. The measurement target portion (second fiber layer M2) is frozen under no load using cold spray or liquid nitrogen, etc., to fix the structure, and then cut in the thickness direction using a cutter blade in this state to expose the cross section of the measurement portion. The cross section is magnified and observed using a scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.), and the magnification is adjusted to 300 times so that the fiber cross section can be measured. Five observation photographs are taken in this state to obtain a cross-sectional observation photograph. Next, the fiber diameters of 30 fibers per photograph are measured, and the arithmetic average value is taken as the fiber diameter of the present invention. When the fibers are not perfectly circular, the line segment that connects two points on the periphery in the cross section and has the maximum across length in the cross section is defined as the long axis, and the line segment that is perpendicular to the long axis and has the maximum length is defined as the short axis. The lengths of the long and short axes of each fiber are then measured by analyzing and calculating them using image analysis software or the like, and the arithmetic average of the long axis length and short axis length of a single fiber is defined as the fiber diameter of each fiber, and the arithmetic average of the fiber diameters of 30 fibers is defined as the fiber diameter of the constituent fibers in the region to be measured. When the nonwoven fabric to be measured is incorporated in a sanitary product such as an absorbent article, the sanitary product is sprayed with cold spray to solidify the hot melt adhesive, and then the nonwoven fabric to be measured is carefully peeled off. This method is common to other measurements in this specification.

[0033] In the nonwoven fabric 10, as shown in FIG. 2, the first fiber layer M1 preferably has an opening 3 penetrating in the thickness direction Z at the bottom 2. This allows the second fiber layer M2 to be exposed from the opening 3 at the bottom 2 of the first fiber layer M1, which is spaced from the one surface side 10T. This further enhances the liquid absorbency of the nonwoven fabric 10. At this time, if the fibers of the wall portion 1B are vertically oriented, the liquid is promoted to descend along the vertically oriented fibers, and can be absorbed more quickly by the water-absorbent fibers 62 of the second fiber layer M2 exposed from the opening 3. In addition, the second fiber layer M2 exposed from the opening 3 is located at the bottom 2 between the convex portions 1, 1 of the first fiber layer M1, and is therefore spaced from the top portion 1A that comes into contact with the skin. In addition, if the fibers of the wall portion 1B are vertically oriented, this action makes it easier to maintain the spaced state. As a result, when one surface side 10T of the nonwoven fabric 10 is used as the skin-facing side of the absorbent article, the return of liquid to the skin-facing side is suppressed, and stickiness on the skin-facing side caused by the absorbent fibers 62 that have absorbed liquid is suppressed, further enhancing the dry feeling. From the viewpoint of improving the above-mentioned function, the opening 3 may be provided in the top portion 1A in addition to the bottom portion 2 or instead of the bottom portion 2.

[0034] The penetration in the opening portion 3 referred to here means that, when focusing on the first fiber layer M1, the portion of the first fiber layer M1 in which the constituent fibers are not arranged penetrates both sides of the first fiber layer M1 in the thickness direction Z.

[0035] The openings 3 are holes that are intentionally formed by processing the first fiber layer M1, unlike the fine holes formed between the fibers, and have a hole area that is much larger than the fine holes formed between the fibers. In FIG. 2, the entire bottom 2 except for the base 1D is shown as the openings 3, but the size of the openings 3 can be appropriately selected depending on the width of the bottom 2, etc. For example, in the first fiber layer M1, the entire bottom 2 except for the base 1D may not be the openings 3, and a fiber layer extending from the base 1D may exist around the openings 3. At least 1.0 mm 2 It is preferable that the hole area is equal to or larger than this. The size of the opening 3 can be measured using the above-mentioned microscope. Specifically, the area of ​​the opening 3 is measured at five points using the microscope, and the average value is taken as the opening area of ​​each opening.

[0036] The area of ​​the opening 3 is set to 1.0 mm2 in order to enhance the liquid permeability. 2 More than 1.5mm is preferable. 2 More preferably, 2.0 mm or more 2 More preferably, the area of ​​the opening 3 is 50 mm 2 Less than 40mm is preferable 2 Less than 35mm is more preferable 2 The following is even more preferred:

[0037] The planar shape of the openings 3 may be various from the viewpoint of enhancing liquid permeability, and examples thereof include a circle, an ellipse, and a rectangle.

[0038] The basis weight of the nonwoven fabric 10 is set to 20 g / m from the viewpoint of improving the texture of the nonwoven fabric. 2 More than 30 g / m is preferable. 2 More preferably, 40 g / m 2 The basis weight of the nonwoven fabric 10 is preferably 100 g / m2 or more so as not to impede the comfortable feel of the wearer. 2 Less than 90 g / m is preferable. 2 Less than 85 g / m is more preferable. 2 The following is even more preferred:

[0039] Nonwoven fabric 10: 4.9mN / cm 2 (0.05gf / cm 2 ) The thickness under load is preferably 0.8 mm or more, more preferably 1.0 mm or more, and even more preferably 1.2 mm or more, from the viewpoint of improving cushioning properties. 2 The above 4.9mN / cm can be measured using a laser displacement meter or similar device under a load. 2 The load is a load that assumes fluffing on the surface of the nonwoven fabric. 2By having the thickness under load within the above range, the liquid backflow prevention performance is improved, making it difficult for the wearer's skin to become wet. In addition, the nonwoven fabric 10 has a strength of 4.9 mN / cm 2 The thickness under load is preferably 10 mm or less, more preferably 7 mm or less, and even more preferably 5 mm or less, from the viewpoint of not impeding the wearer's comfortable use.

[0040] Next, a more preferred embodiment of the uneven structure described above in the nonwoven fabric 10 of this embodiment will be described.

[0041] The wall 1B of the first fiber layer M1 preferably has a shape extending perpendicularly to the direction along the plane of the other surface side 10B of the nonwoven fabric 10 (second fiber layer M2). As a result, the perpendicular wall 1B connects the top 1A and the second fiber layer M2 perpendicularly, and the soft fiber layer of the top 1A tends to remain supported by the elastic fiber layer of the wall 1B. This effect is strengthened by the vertical orientation of the fibers of the wall 1B. As a result, the thickness of the fiber layer of the protrusion 1 is felt through the top 1A, and the multi-stage cushioning due to the presence of the intrusion mixed layer 5 is further enhanced. This makes it easier to obtain a softer touch. More specifically, this soft touch is felt as a gentle and reassuring thickness under light pressure to the touch, and is felt as a resilient and soft thickness that is not easily worn out even when the protrusion 1 is deformed under further pressure. Such excellent cushioning properties further improve the feel of the skin due to the uneven structure described above. In addition, when the fibers of the wall portion 1B are oriented vertically, the effect of promoting the descent of liquid along the fibers is further enhanced, resulting in more excellent liquid absorbency.

[0042] The "vertical" of the wall 1B means that the angle θ with respect to the plane of the other side 10B of the nonwoven fabric 10 (second fiber layer M2) shown in FIG. 1 is not limited to a case where the angle is strictly 90°, but is between 60° and 120°. When the angle is within this range, the wall 1B has a shape that extends at an angle that is substantially recognized as 90° in the thickness direction Z of the nonwoven fabric 10. The angle θ means the intersection angle between the plane of the other side 10B of the nonwoven fabric 10 and the extension line of the wall 1B. Specifically, as shown in FIG. 1, the angle θ means the interior angle among the angles formed by the center line M of the width of the fiber layer of the wall 1B in the cross section in the thickness direction Z including the convex portion 1 and the straight line L tangent to the surface of the other side 10B of the nonwoven fabric 10 (second fiber layer M2). This angle θ can be obtained by observing a micrograph of the cross section obtained by the above-mentioned microscope.

[0043] 1, the wall 1B extends linearly between the top 1A and the second fiber layer M2, and the entire wall 1B is provided perpendicular to the second fiber layer M2. However, this is not limited thereto, and the wall 1B may include a portion that extends curvedly or wavy between the top 1A and the second fiber layer M2. In this case, the angle θ is determined by using the line that connects the boundary point between the top 1A and the wall 1B and the boundary point between the plane of the other surface 10B of the second fiber layer M2 and the wall 1B as the center line M. Although it is preferable that all of the walls 1B extend perpendicular to the second fiber layer M2, some of the walls 1B may not extend perpendicular to the plane of the other surface 10B of the second fiber layer M2. In the latter case, the number of perpendicular walls 1B is preferably 60% or more of the walls 1B in all of the protrusions 1, from the viewpoint of making the above-mentioned action of the nonwoven fabric 10 more effective.

[0044] Next, a specific example (nonwoven fabric 20) of the nonwoven fabric 10 shown in Fig. 1 will be described with reference to Fig. 3 to Fig. 7. The nonwoven fabric 20 has the above-described configuration shown for the nonwoven fabric 10. Note that the nonwoven fabric 20 may have open holes 3 as shown in Fig. 2. 3 to 7, in plan view from one surface side 20T, the first fiber layer M1 has a plurality of ribs 11 extending in one direction Y as the above-mentioned protrusions 1 and arranged at a distance from each other in a direction X intersecting the one direction Y. The other surface side 20B of the ribs 11 has a hollow portion 11C therein. The one direction Y and the direction X intersecting the one direction Y can be appropriately set according to the purpose on one surface side 20T of the nonwoven fabric 20. For example, the one direction Y and the direction X intersecting the one direction Y are preferably perpendicular to each other. When the nonwoven fabric 20 is used as a member on the skin side of an absorbent body, such as a topsheet in an absorbent article, it is preferable that the one direction Y is the longitudinal direction of the absorbent article, and the direction X intersecting the one direction Y is the width direction of the absorbent article.

[0045] The ridges 11 have the same height in the extension direction. The "same height" means that the height measured using a microscope VHX900 (product name, manufactured by Keyence Corporation) is within a range of 0.8 to 1.2 times the average measurement value.

[0046] Each of the ridges 11 includes a crest 11A and a wall 11B supporting the crest 11A. The crest 11A is a fiber layer that contacts the wearer's skin in an absorbent article, and the wall 11B is a fiber layer that connects the crest 11A and the second fiber layer M2 in the thickness direction. That is, when the nonwoven fabric 20 is applied to an absorbent article, the one surface side 20T becomes the skin contact surface side, and the other surface side 20B becomes the non-skin contact surface side. As described above, it is preferable that the fibers of the wall 11B are vertically oriented. In addition, the shape of the wall 11B extends perpendicular to the second fiber layer M2, and connects the crest 11A and the bottom 12 perpendicularly. The longitudinal orientation ratio, which indicates the longitudinal orientation of the fibers in this wall portion 11B, can be measured based on the above-mentioned method (method for measuring the longitudinal orientation ratio of fibers in wall portion 1B) in a cross section perpendicular to the extension direction of the rib portion 11 (a thickness direction cross section at the position of line R1-R1 along direction X intersecting with direction Y in FIG. 3), as shown in FIG. 4. Furthermore, the "vertical" of wall 11B refers to the interior angle between center line M of the width of the fiber layer of wall 11B and straight line L tangent to the surface of the other side 20B of nonwoven fabric 20 (second fiber layer M2) in a cross section perpendicular to the extending direction of rib 11 (thickness direction cross section at line R1-R1 along direction X intersecting direction Y in FIG. 3), as shown in Fig. 4. This angle θ can be determined by observing a micrograph of the cross section along line R1-R1 obtained with the above-mentioned microscope.

[0047] As shown in Fig. 4, the penetrating mixed layer 5 of the second fiber layer M2 is disposed so as to penetrate into each rib portion 11. As shown in Fig. 5, this penetrating mixed layer 5 is disposed so as to extend along the one direction Y, which is the extension direction of the rib portion 11, i.e., the hollow portion 11C, in a cross section along the extension direction of the rib portion 11 (a thickness direction cross section at the position of the line R2-R2 along the one direction Y in Fig. 3). Therefore, the above-mentioned effect of the penetrating mixed layer 5 is exerted over the entire one direction Y along the rib portion 11.

[0048] The nonwoven fabric 20 has, as the above-mentioned convex portion 1 in the first fiber layer M1, the above-mentioned ridge portion 11 and the saddle portion 15 connecting the adjacent ridge portions 11, 11. The saddle portion 15, like the ridge portion 11, protrudes from the second fiber layer M2 to one surface side 20T of the nonwoven fabric 20, and is a three-dimensional fiber layer erected in the thickness direction of the nonwoven fabric 20. More specifically, the saddle portion 15 has a crest 15A on one surface side 20T and a wall portion 15B supporting the crest 15A. The fibers of the wall portion 15B are preferably vertically oriented as described above. In addition, the wall portion 15B extends perpendicular to the second fiber layer M2. The above-mentioned "perpendicular" has the same meaning as the "perpendicular" defined in the above-mentioned ridge portion 11. The longitudinal orientation rate indicating the longitudinal orientation of wall portion 15B in saddle portion 15 and the "vertical" of wall portion 11B can be measured in a cross section perpendicular to the extension direction of saddle portion 15 (thickness cross section at the position of line R3-R3 along one direction Y in FIG. 3) as shown in FIG. 6 in the same manner as the measurement method described above for wall portion 11B.

[0049] The above structure makes it difficult for the ridges 11 connected by the saddle portion 15 to approach each other, and prevents the ridges 11 from falling in one direction due to an external force such as pressure. That is, the saddle portion 15 supports the ridges 11 from the side, improving the shape retention of the ridges 11. This makes it easier for the ridges 11 to maintain their thickness under load. For example, when the nonwoven fabric 20 is incorporated into an absorbent article as a top sheet or the like, even if there is body pressure from the wearer when wearing the absorbent article, the distance between the top portion 11A and the absorbent body side of the other surface side (non-skin contact surface side) 20B is easily maintained, making it even harder for liquid to return to the one surface side (skin contact surface side) 20T. Furthermore, the presence of the saddle portion 15 acts to block excreted liquid between the ridges 11, 11, enhancing the ability to prevent liquid from flowing on one surface side (skin contact surface) 20T of the nonwoven fabric 20.

[0050] In a plan view from one surface side 20T of the nonwoven fabric 20, the saddle portion 15 extends in a direction X intersecting with the direction Y in which the rib portion 11 extends. The direction X in which the saddle portion 15 extends can be various directions as long as it connects adjacent ribs 11, and is preferably a direction perpendicular to the direction Y in which the rib portion 11 extends. For example, it is preferable that the direction Y in which the rib portion 11 extends is the longitudinal direction of the absorbent article, and the direction X in which the saddle portion 15 extends and intersects with the direction Y is the width direction of the absorbent article. Hereinafter, the direction Y and the direction X perpendicular to the direction Y are also referred to as the extension direction Y of the rib portion 11 and the extension direction X of the saddle portion 15. In addition, the planar shape of each saddle portion 15 as viewed from one surface side 20T is not limited to a rectangle as shown in Fig. 3, and may be various shapes. For example, the planar shape of the saddle portion 15 as viewed from one surface side 20T may be such that the width increases toward the ridge portion 11.

[0051] The saddle portions 15 are arranged in a plurality of band regions 16 extending parallel to the ribs 11 between the ribs 11, 11 in a plan view of one surface side 20T of the nonwoven fabric 20. In each band region 16, a plurality of saddle portions 15 are arranged at intervals along the extension direction Y of the ribs 11 running in parallel. The above-mentioned bottom portion 12 is located at the portion where the saddle portions 15 are spaced apart. That is, in each band region 16, the saddle portions 15 and the bottom portion 12 (corresponding to the bottom portion 2 in FIG. 1) are alternately arranged. As a result, the bottom portion 12 is surrounded by the wall portion 11B of the rib portion 11 and the wall portion 15B of the saddle portion 15. More specifically, the region surrounded by the plurality of ribs 11 and the plurality of saddle portions 15, which are three-dimensional fiber layers standing in the thickness direction, is a box-shaped or cylindrical recess, and the bottom portion 12 is arranged at the bottom of the recess. In the example shown in FIG. 3, in a plan view from one surface side 20T of nonwoven fabric 20, ridges 11 and saddles 15 are arranged in a lattice pattern, and bottoms 12 are interspersed in the lattice pattern to form squares.

[0052] Although the saddle portion 15 has a three-dimensional fiber structure similar to that of the ridge portion 11, it is preferable that the saddle portion 15 has a portion that is lower in height from the bottom portion 12 than the ridge portion 11, as shown in Figures 6 and 7. This reduces the contact area with the skin on one surface side 20T of the nonwoven fabric 20, maintaining a pleasant feel against the skin, and increasing breathability to further prevent stuffiness between the surface and the skin. The difference (H3-H4) between the thickness direction height H3 of the rib portion 11 and the thickness direction height H4 of the saddle portion 15 is preferably 0.5 mm or more and 7 mm or less in order to improve the above-mentioned action. The thickness direction height H3 of the rib portion 11 is the thickness direction distance from the plane of the other surface side 10B of the nonwoven fabric 20 (second fiber layer M2) to one surface side 20T of the crest 11A of the rib portion 11. The thickness direction height H4 of the saddle portion 15 is the thickness direction distance from the plane of the other surface side 20B of the nonwoven fabric 20 (second fiber layer M2) to one surface side 20T of the lowest position of the crest 15A of the saddle portion 15.

[0053] (Method of measuring the difference between the height H3 of the ridge portion 11 in the thickness direction and the height H4 of the saddle portion 15 in the thickness direction) As shown in FIG. 6, a thickness direction cross section (thickness direction cross section at the position of line R3-R3 in FIG. 3) of the nonwoven fabric 20 is prepared at the lowest position of the saddle portions 15 along the extension direction of the band region 16 in which the saddle portions 15 are arranged, and the flat surface of the other surface side 20B of the second fiber layer M2 is placed on a horizontal table. The height H3 from the horizontal table to one surface side 20T of the crest 11A of the ridge portion 11 and the height H4 from the horizontal table to one surface side 20T of the crest 15A of the saddle portion 15 are measured. The height difference (H3-H4) is calculated from these measured values. The above-mentioned microscope can be used to measure the height from the horizontal table.

[0054] In addition, the saddle portion 15 has a hollow portion 15C as shown in Fig. 6 from the viewpoint of increasing the liquid absorbency of the nonwoven fabric 20 and the resulting dryness of the surface when the nonwoven fabric 20 is used as a top sheet of an absorbent article, and from the viewpoint of further promoting drainage of liquid to the other surface side 20B. The definition and measurement method of this hollow portion 15C are the same as those of the hollow portion 11C in the ridge portion 11. This increases the liquid absorbency of the nonwoven fabric 20, promotes the diffusion of excreted liquid on the other surface side 20B, and further suppresses liquid retention on the one surface side 20T. As a result, the amount of liquid remaining in the nonwoven fabric 20 is further reduced, making it possible to further reduce the amount of liquid adhering to the skin.

[0055] Furthermore, as shown in the cross section in the extending direction of the saddle portion 15 in Fig. 7 (thickness direction cross section at the position of the line R4-R4 along the direction X intersecting with the direction Y in Fig. 3), it is preferable that the hollow portion 15C of the saddle portion 15 is connected to the hollow portion 11C of the rib portion 11 at the intersection of the saddle portion 15 and the rib portion 11. This allows liquid to flow vertically and horizontally between the hollow portion 15C and the hollow portion 11C on the other surface side 20B of the second fiber layer M2, thereby improving the liquid absorbency of the absorbent fiber of the second fiber layer M2. In addition, the breathability between the hollow portion 15C and the hollow portion 11C is improved, and stuffiness can be suppressed.

[0056] 6 and 7, the penetrating mixed layer 5 of the second fiber layer M2 is disposed so as to penetrate into the saddle portion 15. The penetrating mixed layer 5 extends in the direction X intersecting with the direction Y, which is the extension direction of the saddle portion 15, i.e., the hollow portion 15C. This allows the penetrating mixed layer 5 to exert the above-mentioned effect in the entire direction X along the saddle portion 15. Furthermore, when hollow portions 11C and 15C are connected as shown in FIG. 7, and the intruding mixed layer 5 is connected to hollow portions 11C and 15C and arranged vertically and horizontally in a lattice pattern, the aforementioned cushioning properties, as well as liquid absorbency and the resulting dryness of the surface are uniformly exhibited throughout the nonwoven fabric 10, which is preferable.

[0057] Next, a preferred embodiment of a method for producing the nonwoven fabric 20 will be described with reference to Figures 8 to 12. The production method described below can also be applied to the production method for the nonwoven fabric 10. As shown in FIG. 8, the manufacturing method of this embodiment includes the following four steps (hereinafter, each step may be referred to as step (I), step (II), step (III), and step (IV)). (I) A pressing process in which a first fiber web 100 is placed on a support 120 having an uneven shape having a plurality of protrusions 121 and recesses 125 between the protrusions 121, 121, and the fiber web 100 is pressed and shaped along the recesses 125 by the pressing portion 131 of the pressing member 130 to form an uneven fiber web 101. (II) A step of removing the pushing member 130 from the support 120, and then blowing a first hot air W1 onto the uneven fiber web 101 to fuse the fibers together to obtain an uneven nonwoven fabric 102. (III) A step of supplying the second fiber web 103 and laminating it on the side of the portion of the uneven nonwoven fabric 102 that has been pushed up by the protrusions 121. (IV) A heat-sealing step in which the fibers of the uneven nonwoven fabric 102 and the second fiber web 103 are fused together by blowing a second hot air W2, and the fibers in the second fiber web 103 are fused together.

[0058] The first fibrous web 100 is a precursor of the first fibrous layer M1 in the nonwoven fabric 20 and contains thermoplastic fibers. The second fibrous web 103 is a precursor of the second fibrous layer M2 in the nonwoven fabric 20 and contains a mixture of thermoplastic fibers 61 and water-absorbent fibers 62. The "fiber web" of the first fiber web 100 and the second fiber web 103 refers to a fiber assembly in which constituent fibers including thermoplastic fibers are not fused and fixed but are loosely entangled, and which does not have the shape retention of a sheet by itself. In other words, it is a fiber assembly before being made into a nonwoven fabric. Therefore, the mobility between fibers in the fiber web is high, and the deformation of the fiber web in the pushing process is high. Such first fiber web 100 and second fiber web 103 are each supplied from a carding machine (not shown) to a predetermined thickness.

[0059] In step (I), as shown in FIG. 8(A), the first fiber web 100 on the support 120 is directly pressed with mechanical pressure using a pressing member 130. This forms an uneven fiber web 101 that will become the first fiber layer M1 in the nonwoven fabric 20. This type of shaping results in stronger fiber orientation and perpendicular orientation to the nonwoven fabric plane compared to pressing with non-mechanical pressure such as wind. Furthermore, it is not necessary to apply a large pressing force to increase the unevenness height difference formed on the first fiber web 100, and the first fiber web 100 can be shaped softly. Furthermore, fiber disorder can be suppressed to improve shaping properties.

[0060] The support 120 is drum-shaped as shown in Fig. 8, for example, and has protrusions 121 as shown in Fig. 8(A) on the drum peripheral surface. On the drum peripheral surface of the support 120, a plurality of protrusions 121 are arranged at intervals in one direction (first direction D1) and a direction perpendicular thereto (second direction D2), as shown in Fig. 9, for example. A plurality of protrusion rows 121A, each of which is formed by arranging a plurality of protrusions 121 in the first direction D1, are arranged at a distance from each other in the second direction D2. The recess 125 has a first recess 125A extending in the first direction D1 between the protrusion rows 121A, 121A, and a second recess 125C located between the protrusions 121, 121 in the protrusion row 121A. The second recess 125C is connected to the adjacent first recess 125A and extends intermittently in the second direction D2 via the first recess 125A.

[0061] In the support 120, a plurality of protrusions 121 are arranged corresponding to positions where the bottom portion 12 of the first fiber layer M1 of the nonwoven fabric 20 will be formed. A second recess 125C between the protrusions 121, 121 in the protrusion row 121A is located at a position where the saddle portion 15 of the first fiber layer M1 of the nonwoven fabric 20 will be formed. In other words, the protrusion row 121A is located at a position that will become the band region 16 between the ribs 11, 11 of the first fiber layer M1 of the nonwoven fabric 20. The first recess 125A is located at a position that will become the rib portion 11 of the first fiber layer M1 of the nonwoven fabric 20. The bottom of each recess 125 has a structure that allows hot air to pass through, and for example, has a plurality of holes (not shown).

[0062] The pushing member 130 is in the form of a roll as shown in Fig. 8, for example, and has a pushing portion 131 as shown in Fig. 8(A) on the roll peripheral surface. On the roll peripheral surface of the pushing member 130, a plurality of pushing portions 131 continuing in the first direction D1 are arranged at intervals in the second direction D2 as shown in Fig. 10, for example. Between the pushing portions 131, 131, a recess 132 continuing in the first direction D1 is formed. The pushing portion 131 of the pushing member 130 corresponds to the first recess 125A of the support body 120. The recess 132 of the pushing member 130 corresponds to the protrusion row 121A of the support body 120. The bottom of the recess 132 of the pushing member 130 has a structure that allows hot air to pass through, and for example, a plurality of holes (not shown) are provided therein.

[0063] The height of the pushing portion 131 of the pushing member 130 is preferably 1 mm or more so that it can be sufficiently inserted between the protrusions 121 of the support 120 .

[0064] The first direction D1 and the second direction D2 in the support 120 and the pushing member 130 are preferably a machine direction (MD) and a cross direction (CD) perpendicular to the machine direction in the manufacturing process. The machine direction and the cross direction in the manufacturing process preferably correspond to one direction Y and a direction X crossing the one direction Y in the nonwoven fabric 20, and preferably correspond to the longitudinal direction and the cross direction in an absorbent article including the nonwoven fabric 20. However, the first direction D1 and the second direction D2 are not limited to these.

[0065] In step (I), the protrusions 121 of the support 120 are inserted into the recesses 132 of the support 130. The protrusions 131 of the support 130 are inserted into the first recesses 125A of the support 120 (FIGS. 8(A) and 11). This pushing between the support 120 (FIG. 9) and the pushing member 130 (FIG. 10) makes it possible to suitably form the uneven shape of the first fiber layer M1. The first fiber web 100 is pressed into the first recess 125A of the support 120 by the pressing portion 131 of the pressing member 130 to form a shape. This portion becomes the rib portion 11 in the first fiber layer M1 of the nonwoven fabric 20. At this time, between the protrusion 121 of the support 120 and the pressing portion 131 of the pressing member 130, the fibers of the first fiber web 100 are shaped into a vertically standing shape along the thickness direction. The shaped fibers are not fused and have high mobility, so they are oriented in the thickness direction. This portion becomes the wall portion 11B of the rib portion 11 in the first fiber layer M1 of the nonwoven fabric 20. Meanwhile, the fibers of the first fibrous web 100 are pushed up to the bottom of the recess 132 of the pushing member 130 at the positions of the protrusions 121 of the support 120. This portion becomes the bottom portion 12 of the first fiber layer M1 of the nonwoven fabric 20. The second recess 125C between the protrusions 121, 121 in the protrusion row 121A of the support 120 corresponds to the recess 132 of the pushing member 130, so the pushing portion 131 does not enter. However, the pushing force of the pushing portions 131, 131 of the pushing member 130 acts on both sides of the fibers of the first fiber web 100 in the second recess 125C of the protrusion row 121A. Due to this action, the fibers of the first fiber web 100 in the second recess 125C are stretched in the second direction D2 by the pushing portions 131, 131 on both sides and pushed in the thickness direction, so that the fibers are shaped in the thickness direction and the fiber orientation changes. This portion becomes the saddle portion 15 in the first fiber layer M1 of the nonwoven fabric 20. The saddle portion 15 has an apex 15A and a wall portion 15B, and the wall portion 15B is similar to the wall portion 11B of the ridge portion 11.

[0066] The height of the protrusions 121 of the support 120 and the height of the pushing portion 131 of the pushing member 130 are appropriately determined depending on the thickness of the nonwoven fabric to be manufactured. For example, it is preferably 2 mm or more, more preferably 3 mm or more, even more preferably 5 mm or more, and preferably 15 mm or less, more preferably 10 mm or less, and even more preferably 9 mm or less. Specifically, it is preferably 2 mm or more and 15 mm or less, more preferably 3 mm or more and 10 mm or less, and even more preferably 5 mm or more and 9 mm or less.

[0067] Next, in step (II), after removing the pushing member 130 from the support 120, a first hot air W1 is blown onto the uneven fiber web 101 to fuse the fibers together and obtain an uneven nonwoven fabric 102 (FIG. 8(B)). This uneven nonwoven fabric 102 becomes the first fiber layer M1 of the nonwoven fabric 20. For example, the uneven fiber web 101 is rotated while being held on the support 120, and after passing through the meshing portion between the support 120 and the pushing member 130, the first hot air W1 is blown onto the uneven porous fiber web 101 at the position of the hot air blowing section 140 in FIG. 8(B). The support 120 preferably has a hot air suction section 141 at a position facing the hot air blowing section 140 inside the drum.

[0068] The temperature of the first hot air W1 is set to a temperature capable of melting the thermoplastic fibers constituting the uneven fiber web 101 and forming fused fiber portions at the intersections of the fibers. Considering typical fiber materials used in this type of product, the temperature is preferably 0°C to 70°C higher than the melting point of the thermoplastic fibers constituting the uneven fiber web 101, and more preferably 5°C to 50°C higher. From the viewpoint of effective fusion, the wind speed of the first hot air W1 is preferably 1 m / s or more, and more preferably 2 m / s or more. Also, from the viewpoint of making the device scale compact, the wind speed of the first hot air W1 is preferably 100 m / s or less, and more preferably 80 m / s or less.

[0069] Next, in step (III), the second fiber web 103 is supplied and laminated on the side of the portion (bottom 12) of the uneven nonwoven fabric 102 pushed up by the protrusions 121 (FIG. 8(C)). For example, the uneven nonwoven fabric 102 formed by blowing the first hot air W1 is separated from the drum peripheral surface of the support 120 and transported downstream on a belt conveyer with the side on which the bottom 12 is formed by the protrusions 121 facing up, and the second fiber web 103 is joined and laminated on the side of the bottom 12.

[0070] Next, in step (IV), a second hot air W2 is blown in a fusion furnace 170 to fuse the fibers of the uneven nonwoven fabric 102 and the second fibrous web 103 together, and also fuse the fibers in the second fibrous web 103 together (FIG. 8(D)). This integrates the uneven nonwoven fabric 102 and the second fibrous web 103, and at the same time, turns the second fibrous web 103 into a nonwoven fabric. This nonwoven fabric of the second fibrous web 103 becomes the second fiber layer M2 of the nonwoven fabric 20. At this time, as shown in Fig. 8(D), the uneven nonwoven fabric 102 is placed on the net 180 with the side with the concave-convex nonwoven fabric 102 facing down, and the second hot air W2 is blown onto the second fiber web 103 side, so that the second fiber web 103 is pressed in. The pressed second fiber web 103 penetrates into the hollows 11C of the ridges 11 and the hollows 15C of the saddles 15 of the uneven nonwoven fabric 102 so as to bite into them, and an intrusion mixed layer 5 is formed. In this way, the second fiber layer M2 (a nonwoven fabric of the second fiber web 103) is in close contact with the other surface side 20B of the uneven nonwoven fabric 102 (the first fiber layer M1), and the fibers are integrated by forming fused fiber portions at the intersections of the fibers, thereby obtaining the nonwoven fabric 20 described above.

[0071] Taking into consideration the typical fiber materials used in this type of product, the temperature of the second hot air W2 is preferably 0°C to 70°C higher than the melting point of the thermoplastic fibers that make up the uneven nonwoven fabric 102 and the second fiber web 103, and more preferably 5°C to 50°C higher. The wind speed of the second hot air W2 is preferably 0.3 m / s or more, and more preferably 0.4 m / s or more, from the viewpoint of fusing the fibers in the second fiber web and from the viewpoint of sufficiently fixing the uneven nonwoven fabric 102 and the second fiber web 103. Moreover, from the viewpoint of improving cushioning properties, the wind speed of the second hot air W2 is preferably 50 m / s or less, and more preferably 30 m / s or less.

[0072] In the above manufacturing method, the push-in member 130 is not limited to one having push-in portions 131 continuous in the first direction D1 as shown in Fig. 10. For example, the push-in portions 131 may be formed in a lattice shape, with square-shaped recesses 132 between the lattice-shaped push-in portions 131. In this case, the height of the saddle portion 15 to be formed becomes higher, and the unevenness becomes more distinct.

[0073] In the method for producing the nonwoven fabric 20 described above, when the openings 13 are formed in the bottom portion 2 as shown in FIG. 2, for example, a support male member 120A shown in FIG. 12 can be used. The support male member 120A has a peak 122 at the tip of the projection 121. The peak 122 forms the opening 3 in the bottom portion 12 of the first fiber layer M1.

[0074] In the manufacturing method of the nonwoven fabric of this embodiment, it is preferable to have a cooling process after blowing the first hot air W1. For example, as shown in FIG. 8, it is preferable to arrange a cooling section 160 having a cooling nozzle and a cooling suction section 161 inside the drum of the support 110 opposite each other at a position where the uneven nonwoven fabric 102 obtained by blowing the first hot air W1 is aligned along the outer periphery of the drum of the support 110. This makes it possible to keep the support 120 at a certain temperature or lower, and to peel off the obtained nonwoven fabric while maintaining its shape. As a result, the shape of the walls 11B and 15B of the first fiber layer M1 can be well maintained in the manufactured nonwoven fabric 20, and good cushioning properties, liquid absorbency, and the resulting dryness of the surface can be improved.

[0075] The nonwoven fabric of the present invention can be used in various applications. For example, it can be used as a component of various absorbent articles. The various absorbent articles broadly include articles used to absorb liquids discharged from the body, such as diapers for adults and infants, sanitary napkins, panty liners, and urine pads.

[0076] An absorbent article having the nonwoven fabric of the present invention typically comprises a top sheet, a back sheet, and a liquid-retentive absorbent interposed between the two sheets. In the absorbent article, the nonwoven fabric of the present invention can be suitably used as the top sheet that contacts the wearer's skin. EXAMPLES

[0077] The present invention will be described in more detail below based on examples, but the present invention is not limited thereto. In the examples, "parts" and "%" are all based on mass unless otherwise specified. "←" means that the value is the same as the value in the left column.

[0078] Example 1 Based on the production method shown in FIG. 8, the nonwoven fabric shown in FIGS. 3 to 7 was produced under the following conditions, and this was used as a nonwoven fabric sample of Example 1. The first fiber web 100 is made of thermoplastic fibers having a fineness of 1.3 dtex (fiber diameter 13 μm) and a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) and a basis weight of 30 g / m 2 The fiber web was obtained as follows. The second fiber web 103 is a 40 g / m2 web made of thermoplastic fibers having a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) with a fineness of 2.4 dtex (fiber diameter 17 μm) and cotton fibers (manufactured by Marusan Sangyo Co., Ltd.) with a fineness of 3.0 dtex (fiber diameter 14 μm). 2 The proportion of the thermoplastic fibers 61 to the total number of fibers in the second fiber web 103 was 90%, and the proportion of the water-absorbent fibers 62 to the total number of fibers in the second fiber web 103 was 10%. The MD pitch of the protrusions 121 of the support 120 in plan view was 5 mm, the CD pitch was 5 mm, and the protrusion height was 12.0 mm. The CD pitch of the pushing portion 131 of the pushing member 130 was 5.0 mm, and the pushing portion height was 5.0 mm. The first hot air W1 had a temperature of 160° C. and a wind speed of 20 m / sec. The second hot air W2 had a temperature of 160° C. and a wind speed of 2.0 m / sec.

[0079] The nonwoven fabric sample of Example 1 produced had a first fiber layer M1 and a second fiber layer M2, and had an intrusive mixed layer 5 of the second fiber layer M2 penetrating into the hollows 11C and 15C of the vertical ridges 11 and horizontal ridges 15, which were the convex parts of the first fiber layer M1. The ratio (H2 / H1) of the thickness H2 of the intrusive mixed layer 5 to the thickness H1 of the first fiber layer M1 (thickness of the convex part 1) was 0.33. The nonwoven fabric sample of Example 1 had a compressive strength of 4.9 mN / cm 2 (0.05gf / cm 2 ) The thickness under load was as shown in Table 1.

[0080] Example 2 A nonwoven fabric sample of Example 2 was prepared in the same manner as Example 1, except that the content ratio of the thermoplastic fibers and the water-absorbent fibers in the total number of fibers in the second fibrous web 103 was set to 50% each.

[0081] Example 3 A nonwoven fabric sample of Example 3 was prepared in the same manner as in Example 2, except that the fineness of the thermoplastic fibers constituting the second fibrous web 103 was set to 7.8 dtex (fiber diameter: 33 μm).

[0082] Example 4 As shown in FIG. 2, a nonwoven fabric sample of Example 4 was prepared in the same manner as in Example 2, except that open holes 3 were formed in the bottom portion 2 of the first fiber layer M1.

[0083] Comparative Example 1 A nonwoven fabric sample of Comparative Example 1 was prepared in the same manner as in Example 1, except that the second fibrous web 103 did not contain cotton fibers (water-absorbent fibers).

[0084] Comparative Example 2 A nonwoven fabric sample of Comparative Example 1 was prepared in the same manner as in Example 3, except that the second fibrous web 103 did not contain cotton fibers (water-absorbent fibers).

[0085] Comparative Example 3 The first fibrous web 100 and the second fibrous web 103 used in Example 3 were laminated together, and the laminated web was fixed to the same support 120 as in Example 1, and the same heat treatment as in Example 1 was carried out without performing a pressing operation, to obtain a concave-convex nonwoven fabric having no hollow portions. This concave-convex nonwoven fabric was used as a nonwoven fabric sample for Comparative Example 3.

[0086] The following tests were carried out on each of the above examples and comparative examples, and the results are shown in Table 1 below. The following tests were carried out on diaper samples prepared using each nonwoven fabric sample. The diaper samples were prepared as follows. A commercially available baby diaper (product name "Meries Smooth Air Through S size", Kao Corporation, manufactured in 2020) was used with the top sheet removed to form an absorbent core, and nonwoven fabric cut to 100 x 250 mm from each nonwoven fabric sample of the Examples and Comparative Examples was laminated. The nonwoven fabric was laminated so that the second fiber layer side faced the absorbent core, and the periphery of the laminated nonwoven fabric was fixed to prepare a diaper for evaluation.

[0087] (1) Cushioning properties (compression characteristics under small loads) In the present invention, the compression characteristic under a small load is a value measured by the following method, and is defined as a characteristic value that represents the cushioning feeling. It has been found that this compression characteristic value under a small load correlates with the cushioning feeling. The higher the compression characteristic value (under a small load), the easier it is to be crushed by a small load (the easier it is to make a depression when touched by a finger, etc.), and it can represent the goodness of the human sense of cushioning. The measurements are carried out in an environment of 22°C and 65% RH. The data on which the compression characteristic values ​​under a small load are calculated is measured using a KES FB3-AUTO-A (product name) manufactured by Kato Tech Co., Ltd. The nonwoven fabric to be measured is cut into three pieces measuring 20 cm x 20 cm to prepare measurement samples. Next, one of the measurement samples is placed facing up on the test table. Next, a 2 cm2 area measurement sample is cut into three pieces measuring 20 cm x 20 cm. 2 The specimen is compressed between steel plates with circular flat surfaces. The compression speed is 20μm / sec, and the maximum compression load is 9.80cN / cm. 2 (10.0gf / cm 2 ), and the recovery process is also measured at the same speed. At this time, the displacement between the steel plates is x (mm), and the load is y (cN / cm 2 ) and the position of the point where the load is detected is set to x=0 and measured in the direction of compression. The value of x increases as the load is compressed. The compression characteristic value under a small load is calculated by extracting the amount of deformation in thickness under a small load from the measured data (x, y). Specifically, the first load, which is not in the recovery process, is 0.29 cN / cm 2 (0.30gf / cm 2 ) to 0.98cN / cm 2 (1.00gf / cm 2 The load and deformation data between x and y are extracted, and an approximation line is calculated for the relationship between x and y using the least squares method. The slope of the line is the characteristic value (unit: cN / cm 2 ) / mm). Measure three locations on one measurement sample. Measure a total of nine locations on three samples. Calculate the characteristic values ​​at each of the nine locations, and use the average value as the compression characteristic value of the nonwoven fabric under a small load. In measuring a nonwoven fabric, if the nonwoven fabric to be measured is used as a component of an absorbent article and is joined to other components by adhesives, fusion, or the like, it is preferable to remove the joints with the other components and then remove the nonwoven fabric from the absorbent article without forcibly peeling it off. Methods for removing such joints include, for example, applying a solvent, blowing hot air with a dryer, and spraying with a cold spray (for example, a commercially available product manufactured by Nichiban Co., Ltd.). In particular, from the viewpoint of minimizing deterioration of the nonwoven fabric to be measured, it is preferable to spray the joints between the nonwoven fabric to be measured and other components with a cold spray as described above, and then peel off the nonwoven fabric to be measured.

[0088] (2) Absorbency test (liquid absorption time) 13.6g / cm for nonwoven fabric 2 A pressure load of 1017 mm was evenly applied to the nonwoven fabric. 2 ) and injected artificial urine. 30g of artificial urine was injected three times every 10 minutes, and the time (seconds) until the entire amount was absorbed was measured. When artificial urine was no longer visible inside the cylinder, it was deemed that the entire amount was absorbed. The above procedure was repeated three times, and the average of the three times was taken as the liquid absorption time (seconds). The shorter the liquid absorption time, the easier it is for the liquid to penetrate inside. In other words, the liquid absorption ability is excellent.

[0089] (3) Absorbency test (liquid return test) 30 g of colored artificial urine (composition: urea 1.940% by mass, sodium chloride 0.795% by mass, magnesium sulfate 0.110% by mass, calcium chloride 0.062% by mass, potassium sulfate 0.197% by mass, Red No. 2 (dye) 0.010% by mass, water (approximately 96.88% by mass) was injected over a period of 10 seconds into a position 165 mm from the ventral edge in the longitudinal direction of this absorbent article and at the center in the width direction. 10 minutes after the start of injection, 30 g was injected again. This operation was repeated once more, and a total of 90 g of artificial urine was injected. The temperature of the test atmosphere was room temperature (20±5°C), and the temperature of the artificial urine used was room temperature (20±5°C). Ten minutes after the completion of the injection, ten sheets of Advantech filter paper No. 4A (100 mm x 100 mm, mass measurement W1) were stacked and placed on the nonwoven fabric with the injection point at the center. A pressure of 3.5 kPa was applied through a 5 mm thick, 100 mm x 100 mm acrylic plate, and the mass of the filter paper was measured after two minutes (W2), and the amount of liquid return was calculated according to the following formula (I). Liquid return amount (mg) = Mass of filter paper after pressure (W2) - Initial mass of filter paper (W1) The above procedure was carried out three times, and the average of the three measurements was taken as the amount of liquid returning (mg). The smaller the amount of liquid returning, the less likely it was to cause liquid returning, and the higher the evaluation.

[0090] [Table 1]

[0091] As shown in Table 1, the nonwoven fabric samples of each Example had higher compression deformation characteristics under a small load and showed excellent cushioning properties compared to the nonwoven fabric samples of each Comparative Example. At the same time, the nonwoven fabric samples of each Example had a shorter liquid absorption time compared to the nonwoven fabric sample of Comparative Example 3, which does not have a hollow portion, and the amount of liquid return was smaller than the nonwoven fabric samples of each Comparative Example. From the above, the nonwoven fabric samples of each Example simultaneously had excellent cushioning properties compared to each Comparative Example and a high surface dryness when absorbing liquid. [Explanation of symbols]

[0092] M1 First fiber layer M2 2nd fiber layer 1 Convex part 1A Top 1B Wall section 1C Hollow part 2 bottom 3 Opening part 5 Ingress mixed layer 10, 20 Nonwoven fabric 10T, 20T One side 10B, 20B other side

Claims

1. A non-woven fabric having a first fiber layer and a second fiber layer laminated in the thickness direction, each fiber layer including a fiber fusion part at the intersection of the fibers, The first fiber layer has an uneven structure including a plurality of convex portions and bottoms provided between adjacent convex portions. Each of the plurality of convex portions includes a top portion and a wall portion supporting the top portion, and has a hollow portion inside. The second fiber layer is provided on the side where the bottom of the first fiber layer is located. The second fiber layer includes thermoplastic fibers and water-absorbent fibers, and a mixed layer of thermoplastic fibers and water-absorbent fibers penetrates into the hollow portion of the first fiber layer. A non-woven fabric for absorbent articles.

2. The non-woven fabric for absorbent articles according to claim 1, wherein the ratio of the number of water-absorbent fibers in the constituent fibers of the second fiber layer is 10% or more and 50% or less.

3. The non-woven fabric for absorbent articles according to claim 1, wherein the fiber diameter of the thermoplastic fibers contained in the second fiber layer is larger than the fiber diameter of the water-absorbent fibers.

4. The non-woven fabric for absorbent articles according to claim 1, wherein the first fiber layer has an opening portion penetrating in the thickness direction at the bottom.

5. The basis weight is 20 g / m ２ or more and 100 g / m ２ or less. The non-woven fabric for absorbent articles according to claim 1.

6. The thickness under a load of 4.9 mN / cm ２ is 1.0 mm or more and 10 mm or less. The non-woven fabric for absorbent articles according to claim 1.

7. The non-woven fabric for absorbent articles according to claim 1, wherein the fibers of the wall portion are vertically oriented.

8. An absorbent article having the non-woven fabric for absorbent articles according to any one of claims 1 to 7.

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