Nonwoven fabric for absorbent articles

Abstract

To provide a nonwoven fabric for absorbent article capable of achieving high liquid permeability to excreted liquids having different properties from low viscosity to high viscosity.SOLUTION: A nonwoven fabric 10 has a first fiber layer M1 and a second fiber layer M2 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 1 and a plurality of bottom parts 2 disposed between adjacent convex parts. A first aperture 31 penetrating in the thickness direction is disposed on each of the plurality of bottom parts. A plurality of second apertures 32 are disposed on the second fiber layer. The nonwoven fabric includes a plurality of vertical open holes 5 at which the first aperture and the second aperture penetrate in the thickness direction. The vertical open hole is located at a region sandwiched between concave parts in a plane direction of the nonwoven fabric, and the second aperture constituting the vertical open hole exists across the first aperture and convex parts of the first fiber layer in the nonwoven fabric for absorbent article.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Nonwoven fabrics are used in a variety of applications, such as as components for absorbent products like diapers and sanitary napkins, and various types with diverse structures have been developed. For example, Patent Document 1 describes a nonwoven fabric having an uneven structure as a surface sheet for an absorbent article. The nonwoven fabric described in Patent Document 2 has a structure in which a flat fiber layer is laminated on the recessed side of an uneven fiber layer. Patent Document 3 describes a nonwoven fabric as a surface sheet for an absorbent article, in which an upper layer with an uneven structure and a flat lower layer are laminated, and both layers have through holes. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-467 [Patent Document 2] Japanese Patent Publication No. 2019-44293 [Patent Document 3] Japanese Patent Publication No. 2021-112421 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The aforementioned uneven structure enhances the cushioning properties of the nonwoven fabric. In addition, if the nonwoven fabric is used, for example, as a surface sheet that comes into contact with the wearer's skin in an absorbent product, the uneven structure can help to move the excretory fluid in the thickness direction, keeping it away from the wearer's skin and reducing residual fluid. However, the excretory fluids absorbed by absorbent articles actually have various properties, particularly various viscosities, and their behaviors in absorbent articles differ depending on the viscosity. For example, the lower the viscosity, the higher the mobility of the excretory fluid and the easier it is to spread wet in the planar direction. The higher the viscosity, the lower the mobility of the excretory fluid and the easier it is to remain on the surface. In recent years, in absorbent articles, from the viewpoint of reducing the adhesion of excretory fluid to the skin and enhancing the dryness of the surface, it is required to exhibit excellent liquid absorbency that can respond to excretory fluids of various viscosities and quickly transfer them to the absorber. In this regard, there is room for further improvement in the nonwoven fabric used as a constituent member of absorbent articles.

[0005] In view of the above points, the present invention relates to a nonwoven fabric for absorbent articles that can achieve high liquid permeability for excretory fluids having different properties from low viscosity to high viscosity.

Means for Solving the Problems

[0006] The present invention is a nonwoven fabric having a first fiber layer and a second fiber layer laminated in the thickness direction, each fiber layer including fiber fusion portions at intersections of fibers. The first fiber layer has a concavo-convex structure including a plurality of convex portions and a plurality of bottom portions provided between adjacent convex portions. Each of the plurality of convex portions includes a top portion and a wall portion supporting the top portion. Each of the plurality of bottom portions is provided with a first opening portion penetrating in the thickness direction. The second fiber layer is provided on the side of the first fiber layer where the bottom portion is located. In the second fiber layer, a plurality of second opening portions penetrating in the thickness direction are intermittently arranged in the planar direction of the nonwoven fabric. The nonwoven fabric includes a plurality of concave portions in which the second fiber layer is laminated in the thickness direction with respect to the first opening portion, and a plurality of vertical through-hole portions in which the first opening portion and the second opening portion penetrate in the thickness direction. The vertical through-hole portions are in a region sandwiched by the concave portions in the planar direction of the nonwoven fabric, and the second opening portions constituting the vertical through-hole portions exist across the first opening portion and the convex portion of the first fiber layer. A nonwoven fabric for absorbent articles is provided.

[0007] Further, the present invention places a first fiber web on a support having a concavo-convex shape with a plurality of protrusions and recesses between the protrusions, and along the recesses, the first fiber web is pushed in by a pushing portion of a pushing member to be shaped, and openings are formed at locations corresponding to the protrusions, thereby forming a concavo-convex perforated fiber web having an opening surface on the side opposite to the support. A pushing step; after removing the pushing member from the support, blowing a first hot air onto the concavo-convex perforated fiber web to fuse the fibers to obtain a concavo-convex perforated non-woven fabric; blowing a second hot air onto a second fiber web to fuse the fibers to form openings penetrating in the thickness direction at intervals in the planar direction to obtain a flat perforated non-woven fabric; laminating the flat perforated non-woven fabric on the opening surface side of the concavo-convex perforated non-woven fabric; and a thermal fusion step of blowing a third hot air to fuse the fibers of the concavo-convex perforated non-woven fabric and the flat perforated non-woven fabric, and provides a method for manufacturing a non-woven fabric having these steps.

Advantages of the Invention

[0008] The non-woven fabric for absorbent articles of the present invention can achieve high liquid permeability with respect to excretory fluids having different properties from low viscosity to high viscosity. Further, according to the method for manufacturing the non-woven fabric for absorbent articles of the present invention, the above-mentioned non-woven fabric for absorbent articles of the present invention can be preferably manufactured.

Brief Description of the Drawings

[0009] [Figure 1] It is a cross-sectional view schematically showing a preferred embodiment of the non-woven fabric for absorbent articles according to the present invention. [Figure 2] It is a plan view schematically showing a specific example of the non-woven fabric for absorbent articles of the present embodiment from one surface side. [Figure 3] (A) is a cross-sectional view taken along line R1-R1 of the non-woven fabric for absorbent articles shown in FIG. 2, and (B) is a cross-sectional view taken along line R2-R2 of the non-woven fabric for absorbent articles shown in FIG. 2. [Figure 4] (A) is a cross-sectional view taken along line R3-R3 of the non-woven fabric for absorbent articles shown in FIG. 2, and (B) is a cross-sectional view taken along line R4-R4 of the non-woven fabric for absorbent articles shown in FIG. 2. [Figure 5] It is a cross-sectional view taken along line R5-R5 of the non-woven fabric for absorbent articles shown in FIG. 2. [Figure 6] This is a schematic diagram illustrating a preferred embodiment of the method for manufacturing a nonwoven fabric for absorbent articles according to the present invention, where (A) shows a pressing step, (B) shows a step of obtaining an uneven perforated nonwoven fabric with a first hot air, (C) shows a step of laminating a flat perforated nonwoven fabric onto an uneven perforated nonwoven fabric, and (D) shows a step of integrating the uneven perforated nonwoven fabric and the flat perforated nonwoven fabric with a third hot air. [Figure 7] This is a plan view of the support structure. [Figure 8] This is a plan view of the push-in component. [Figure 9] This is a plan view showing the support and the pressing member combined. [Modes for carrying out the invention]

[0010] 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 the nonwoven fabric. The nonwoven fabric 10 of this embodiment is a so-called thermal bond nonwoven fabric having fiber fusion portions at the intersections of fibers. For example, an air-through nonwoven fabric is formed by an air-through method to create the fiber fusion portions. 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 and are described later, contain thermoplastic fibers as their constituent fibers and are nonwoven fabrics that have the fiber fusion portions formed. The first fiber layer M1 and the second fiber layer M2 are integrated by the fiber fusion portions at the intersections of their respective fibers.

[0011] As shown in Figure 1, 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. The nonwoven fabric 10 has a front side 10T and a back side 10B, with the first fiber layer M1 on one side 10T and the second fiber layer M2 on the other side 10B. In the nonwoven fabric 10, for example, one side 10T can be used as the usable side. When the nonwoven fabric 10 is used as a component on the skin side of an absorbent article, for example, as a surface sheet, one side 10T can be the skin side. In this case, the first fiber layer M1 is also called the upper layer and the second fiber layer M2 is also called the lower layer. Note that the above-mentioned one side 10T and the other side 10B refer to the front and back sides of the entire nonwoven fabric 10, as well as the front and back sides of the first fiber layer M1 and the second fiber layer M2, respectively. Furthermore, the thickness direction Z of the nonwoven fabric 10 also refers to the thickness directions Z of the first fiber layer M1 and the second fiber layer M2, respectively.

[0012] The first fiber layer M1 has a plurality of protrusions 1 projecting from one side 10T and a plurality of bottoms 2 provided between adjacent protrusions 1, 1. As a result, the first fiber layer M1 has an uneven structure in the thickness direction Z. The protrusions 1 are three-dimensional fiber layers erected in the thickness direction Z of the first fiber layer M1 and are located higher on one side 10T than the bottoms 2. Each of the plurality of protrusions 1 comprises a top 1A and a wall 1B that supports the top 1A.

[0013] The outer shape of one side 10T of the top portion 1A may be a flat surface or a curved surface. From the viewpoint of making the tactile feel softer when it is the surface that comes into contact with the wearer's skin, it is preferable that one side 10T of the top portion 1A is a dome-shaped or arched curved surface.

[0014] The fibers of the wall portion 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 referred to here means the direction along the plane (for example, a flat base) that is in contact with the surface of the other side 10B of the nonwoven fabric 10 (second fiber layer M2). This longitudinal orientation of the fibers increases the support force of the wall portion 1B in the thickness direction Z relative to the top portion 1A and the second fiber layer M2, making it easier to maintain the thickness of the convex portion 1 of the nonwoven fabric 10 even under load. As a result, the nonwoven fabric 10, including the first fiber layer M1 and the second fiber layer M2, retains its thickness well, and combined with the elasticity of the fiber structure of the fiber layers, it provides excellent cushioning. In other words, the nonwoven fabric 10 has excellent softness against the skin. Furthermore, when the nonwoven fabric 10 is used as a component on the skin side of an absorbent article, such as a surface sheet, the effect of liquid permeation of bodily fluids is more easily sustained even under load, and liquid return from the absorbent to the skin side (wet back) is suppressed.

[0015] The longitudinal orientation of the fibers in the wall portion 1B means that there are many fibers along the thickness direction Z of the first fiber layer M1, and that the longitudinal orientation rate obtained by the measurement method described later is 60% or more. From the viewpoint of further enhancing the above effect, 61% or more is preferable, and 62% or more is more preferable. Furthermore, there is no particular upper limit to the longitudinal orientation rate, but from the viewpoint of creating intersections between oriented fibers to form fusion points and creating a columnar structure that can withstand force, 90% or less is preferable, 85% or less is more preferable, and 80% or less is even more preferable.

[0016] (Method for measuring the longitudinal orientation ratio of fibers in wall section 1B) As shown in Figure 1, measurements are taken on wall section 1B using the following procedure. Specifically, the fiber layer cross-section of the wall portion 1B defined in the thickness direction cross-section of the nonwoven fabric 10, including the convex portion 1 and bottom portion 2 of the first fiber layer M1 and the second fiber layer M2, is observed at 35x magnification using a scanning electron microscope (SEM). A square line with sides of 500 μm is drawn on the observed image as a reference line. Each side of the square (reference line) is defined as a side perpendicular to the thickness direction and the plane direction, respectively, in the cross-section of the nonwoven fabric 10. The total number of fibers passing through the reference line formed by each side of the square is counted. Fibers passing through the square reference line perpendicular to the plane direction of the nonwoven fabric 10 are defined as "transverse fiber count," and fibers passing through the square reference line perpendicular to the thickness direction of the nonwoven fabric 10 are defined as "longitudinal fiber count." The longitudinal orientation rate is calculated as (longitudinal fiber count) / (transverse fiber count + longitudinal fiber count) × 100 = longitudinal orientation rate (%). These are measured at 10 points 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 the straight line L tangent to the surface of the other side 10B of the second fiber layer M2, as shown in Figure 1. The thickness direction Z corresponds to the direction perpendicular to the straight line L.

[0017] In the cross-section of the nonwoven fabric 10 in the thickness direction Z, including the convex portion 1 and the bottom portion 2 of the first fiber layer M1 described above, the fiber layer of the wall portion 1B can be partitioned by the following method. Specifically, a nonwoven fabric 10 having a cross-section in the thickness direction Z including the top portion 1A and wall portion 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 (the other side 10B) facing downwards. Then, a flat plate (for example, a flat acrylic plate) is placed on the top portion 1A side (the other side 10T) of the nonwoven fabric 10 and a pressure of 4.9 mN / cm is applied. 2A load is applied. In this state, the cross-section in the thickness direction Z is observed at 20x magnification using the microscope, and the fiber layer of the first fiber layer M1 that is in contact with the flat plate is defined as the top portion 1A. The portion connecting the end of the top portion 1A and the surface of one side 10T of the second fiber layer M2 is defined as the wall portion 1B. When determining the boundary between the top portion 1A and the wall portion 1B, the thickness of the top portion 1A in the portion without the wall portion 1B is defined as the thickness of the end of the top portion 1A, and the portion excluding that thickness is defined as the wall portion 1B. Furthermore, the wall portion 1B has an end (also called the base portion 1D) on the other side 10B, and the bottom portion 2 refers to the region provided between adjacent protrusions 1, 1, including the base portion 1D.

[0018] The bottom portion 2 of the first fiber layer M1 is located at the bottom (including the base portion 1D) of a recess (including the base portion 1D) that is recessed on the other side 10B between the protrusions 1, 1, and is adjacent to the second fiber layer M2. Each of these multiple bottom portions 2 has a first opening portion 31 that penetrates in the thickness direction Z. The penetration in the first opening portion 31 here means that, when focusing on the first fiber layer M1, the portion of the first fiber layer M1 that does not contain constituent fibers penetrates both sides of the first fiber layer M1 in the thickness direction Z.

[0019] The first opening 31, unlike the fine pores formed between the fibers, is a pore intentionally formed by processing the first fiber layer M1, and has a much larger pore area than the fine pores formed between the fibers. In Figure 1, the entire bottom 2 except for the base 1D is shown as the opening 3, but the size of the first opening 31 can be appropriately selected according to the width of the bottom 2, etc. For example, in the first fiber layer M1, instead of making the entire bottom 2 except for the base 1D the opening 3, there may be a fiber layer extending from the base 1D around the first opening 31. At least 1.0 mm 2 It is preferable to have the above-mentioned pore area. The size of the first opening 31 can be measured using the aforementioned microscope. Specifically, the area of ​​each first opening 31 is measured at 10 locations using the microscope, and the average value of these measurements is taken as the pore area of ​​each opening.

[0020] The planar shape of the first opening 31 can be various from the viewpoint of improving liquid permeability, and examples include circular, elliptical, rectangular, and rhombus shapes.

[0021] The first opening 31 is located in the region sandwiched between the adjacent protrusions 1 and their walls 1B. This allows the nonwoven fabric 10 to be used as a surface sheet, for example, on the skin side of an absorbent article, so that the excretory liquid received from one side 10T can be directly lowered along the walls 1B to the first opening 31 and quickly permeated to the absorbent below. The outer periphery of the first opening 31 may be formed by the lower end of the wall portion 1B, and the constituent fibers of the first fiber layer M1 (constituent fibers of the bottom portion 2) may be arranged between the lower end of the wall portion 1B and the outer periphery of the first opening 31. When there are constituent fibers of the first fiber layer M1 between the lower end of the wall portion 1B and the outer peripheral edge of the first opening portion 31 (when the first opening portion 31 is part of the bottom portion 2 and constituent fibers of the first fiber layer are present in the bottom portion 2), it is preferable from the viewpoint of liquid permeability that the planar separation distance between the lower end of the wall portion 1B and the outer peripheral edge of the first opening portion 31 be 0.5 mm or less. Note that when constituent fibers of the first fiber layer M1 are present in the bottom portion 2 in this manner, the constituent fibers of the first fiber layer M1 are not considered to be part of the wall portion 1B.

[0022] The second fiber layer M2 is located on the side of the first fiber layer M1 where the bottom is located. Multiple second openings 32 that penetrate in the thickness direction Z are intermittently arranged in the planar direction of the nonwoven fabric 10 in the second fiber layer M2. The second openings 32, like the first openings 31, are holes intentionally formed by processing the second fiber layer M2, and have a hole area that is much larger than the diameter of the fine holes formed between the fibers. Furthermore, the penetration in the second openings 32 means that, when focusing on the second fiber layer M2, the portion of the second fiber layer M2 where no constituent fibers are arranged penetrates both sides of the second fiber layer M2 in the thickness direction Z. The planar shape of the second opening 32 can be various from the viewpoint of improving liquid permeability, and examples include circular, elliptical, rectangular, and rhombus shapes. Unlike the first fiber layer M1, the second fiber layer M2 preferably has a flat surface. It is preferable that at least the other side 10B is a flat surface, and it is more preferable that both sides are flat surfaces. In this case, a flat surface means that, except for the openings and their edges, it is not processed to create irregularities.

[0023] The nonwoven fabric 10, in the laminated structure of the first fiber layer M1 and the second fiber layer M2 described above, has multiple concave portions 4 in which the first opening portion 31 and the second fiber layer M2 are laminated in the thickness direction Z, and multiple upper and lower through-hole portions 5 through which the first opening portion 31 and the second opening portion 32 penetrate in the thickness direction Z. As described above, the first opening portion 31 that constitutes these concave portions 4 and upper and lower through-hole portions 5 is located at the bottom portion 2. That is, the concave portions 4 and upper and lower through-hole portions 5 are located at the bottom portion 2 between the convex portions 1 in the first fiber layer M1. The upper and lower through-holes 5 are located in the region sandwiched between the concave portions 4 in the planar direction X of the nonwoven fabric 10 (for example, regions J1 and J2 shown in Figure 1). In this arrangement, the upper and lower through-holes 5 and the concave portions 4 are in close proximity, but are separated by the convex portions 1 and their walls 1B in the first fiber layer M1. Therefore, the nonwoven fabric 10 has a structure that makes it easier for wastewater to move from one side 10T to the other side 10B rather than diffusing in the planar direction X. Because the concave portions 4 and the upper and lower through-holes 5 are in close proximity and coexist via the convex portions 1, the concave portions 4 and the upper and lower through-holes 5 can work together to improve the liquid permeability of the nonwoven fabric 10 in the thickness direction Z. Therefore, when the nonwoven fabric 10 receives excrement on one side 10T, the excrement is allowed to descend from the top 1A of the convex portion 1 along the wall portion 1B, suppressing liquid diffusion in the planar direction X. This effect is enhanced by the longitudinal orientation of the fibers in the wall portion 1B. At this time, the concave portion 4 and the upper and lower through-hole portions 5 have the following effects on the descended excrement. Specifically, the concave portion 4 can quickly draw low-viscosity excrement (or its components; for example, thin menstrual blood, urine) to the other side 10B through the capillary force of the constituent fibers of the second fiber layer M2. In the upper and lower through-hole portions 5, in addition to the low-viscosity excrement mentioned above, high-viscosity excrement (or its components; for example, thick menstrual blood, loose stool) can be directly and quickly permeated to the other side 10B. The combination of the concave portion 4 and the upper and lower through-hole portions 5 allows for the rapid permeation and absorption of any excrement, from low-viscosity to high-viscosity, or even in a mixed state. For example, it can rapidly permeate and absorb both urine and loose stool simultaneously. Note that "low viscosity" refers to 5 cp or less, and "high viscosity" refers to 10 cp or more. Furthermore, as mentioned above, in the concave portion 4, the first opening portion 31 of the first fiber layer M1 is covered with the constituent fibers of the second fiber layer M2. Because the upper and lower through-hole portions 5 are arranged in the region sandwiched by the concave portion 4, the capillary force of the constituent fibers of the second fiber layer M2 can extend not only to the concave portion 4 but also to the upper and lower through-hole portions 5. As a result, the permeation rate (liquid absorption rate) of liquids of various viscosities in the nonwoven fabric 10 can be increased compared to when the upper and lower through-hole portions 5 are arranged alone, and liquid diffusion on one side 10T can be further suppressed. In addition, due to the action of the aforementioned capillary force, the suppression force against the return of excretory liquid that has permeated to the other side 10B to the one side 10T is increased.

[0024] In addition, the nonwoven fabric 10 has a second opening 32 that constitutes the upper and lower through-holes 5, which spans the first opening 31 and the protrusion 1 of the first fiber layer M1. That is, at the location of the upper and lower through-holes 5, the opening on the other side 10B is larger than the opening for liquid intake on one side 10T. This makes it easier for the waste liquid that permeates from one side 10 through the upper and lower through-holes 5 to diffuse on the other side 10B, thereby increasing the liquid permeation rate in the nonwoven fabric 10 and suppressing liquid diffusion and residue on one side 10T. This is particularly effective in improving the liquid permeation rate for high-viscosity waste liquid that tends to remain in one place. Furthermore, the second opening 32 that constitutes the upper and lower through-holes 5 extends in the planar direction of the other side 10B beyond the location of the upper and lower through-holes 5 to a position that overlaps with the protrusion 1. Therefore, at the extension point, the second opening 32 can easily draw in liquid from the concave portion 4 adjacent to the protrusion 1. Therefore, even if there is a high-viscosity waste liquid in the concave portion 4, it is easily transferred to the second opening portion 32. Also, even if the amount of low-viscosity waste liquid drawn in by the concave portion 4 becomes excessive, it is easily transferred from the constituent fibers of the second fiber layer M2 that constitutes the concave portion 4 to the adjacent second opening portion 32. In this way, on the other side 10B of the nonwoven fabric 10, it is possible to transfer liquid between the second opening portion 32 and the constituent fibers of the second fiber layer M2. As a result, the nonwoven fabric 10 can rapidly permeate waste liquids of a wider variety of viscosities by increasing the liquid permeation rate.

[0025] From the viewpoint of the above-mentioned effects, in the planar direction X of the nonwoven fabric, it is preferable that the upper and lower through-holes 5 are located in a region surrounded by concave portions 4 on all sides (front, back, left, and right). More specifically, it is preferable that the upper and lower through-holes 5 are surrounded by convex portions 1 on all sides (front, back, left, and right), and further surrounded by concave portions 4. Furthermore, in the region sandwiched between the concave portions 4, there may be one upper and lower through-hole portion 5 (for example, region J1 shown in Figure 1), or there may be multiple (for example, region J2 shown in Figure 1). If there are multiple, it is preferable that a convex portion 1 is interposed between adjacent upper and lower through-hole portions 5, 5, as shown in region J2 in Figure 1. The upper and lower through-hole portions 5 may be smaller than or the same as the hole area of ​​the first opening portion 31, but from the viewpoint of absorbing high-viscosity discharge liquid, it is preferable that the hole area is the same as or close to that of the first opening portion 31.

[0026] When such a nonwoven fabric 10 is used as a component on the skin-facing side of an absorbent article, such as a surface sheet, the nonwoven fabric 10 can achieve high liquid permeability to a variety of excretory fluids with different properties ranging from low to high viscosity, regardless of the viscosity of the excretory fluid. Furthermore, on one side 10T, the nonwoven fabric 10 has excellent cushioning properties due to the convex portion 1 supported by the wall portion 1B in which the fibers are preferably oriented vertically, providing a reassuring thickness and excellent softness against the skin. In addition, the presence of upper and lower through-holes 5 in the region sandwiched between the concave portions 4 enhances the visibility of the perforation structure, allowing for a strong appeal to consumers regarding the high liquid absorbency.

[0027] Furthermore, the area ratio of the upper and lower through-holes 5 to the total area of ​​the nonwoven fabric 10 viewed from above is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more, from the viewpoint of enhancing the liquid permeability effect mentioned above. Also, from the viewpoint of suppressing liquid backflow, the area ratio is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less. The area of ​​the upper and lower through-holes 5 can be measured using the microscope mentioned above. For this measurement, first, the nonwoven fabric 10 is cut to a size of 50 mm x 50 mm, and the total area of ​​the upper and lower through-holes 5 in that area is measured. Then, the area ratio of the upper and lower through-holes 5 to the total area of ​​the nonwoven fabric 10 viewed from above is calculated using the following formula. The area ratio (%) of the upper and lower through-holes 5 in relation to the total area of ​​the nonwoven fabric 10 when viewed in plan view = (Total area of ​​upper and lower through-holes 5) / (50 × 50) × 100 Note that the plan view of the entire nonwoven fabric 10 is a plan view from one side 10T.

[0028] From the viewpoint of enhancing the liquid permeability effect, the area ratio of the concave portion 4 to the total area of ​​the nonwoven fabric 10 viewed in plan is preferably 3% or more, more preferably 4% or more, and even more preferably 5% or more. Furthermore, from the viewpoint of suppressing liquid backflow, the area ratio is preferably 35% or less, more preferably 30% or less, and even more preferably 25% or less. The area of ​​the concave portion 4 can be measured in the same manner as the area of ​​the upper and lower through-hole portions 5 described above.

[0029] In the nonwoven fabric 10, it is preferable that the fiber diameter (E2) of the constituent fibers of the second fiber layer M2 is smaller than the fiber diameter (E1) of the constituent fibers of the first fiber layer M1. This increases the difference in capillary force between the second fiber layer M2 and the first fiber layer M1, thereby improving the permeability of wastewater (especially low-viscosity wastewater) through the concave portion 4. In addition, the pulling force of the second fiber layer M2 towards wastewater (especially high-viscosity wastewater) that has permeated through the upper and lower through-hole portions 5 increases, making it easier to diffuse on the other side 10B. From this viewpoint, the ratio (E2 / E1) of the fiber diameter (E2) of the constituent fibers of the second fiber layer M2 to the fiber diameter (E1) of the constituent fibers of the first fiber layer M1 is preferably 1.0 or less, more preferably 0.98 or less, and even more preferably 0.95 or less. Furthermore, from the viewpoint of absorption rate, the ratio (E2 / E1) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. Furthermore, within the range that satisfies the above ratio (E2 / E1), the fiber diameter (E2) of the constituent fibers of 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 increasing capillary force. The fiber diameter (E2) of the constituent fibers of the second fiber layer M2 is preferably 3 μm or more, more preferably 4 μm or more, and even more preferably 5 μm or more, from the viewpoint of diffusion to the layer below. Furthermore, within the range that satisfies the above ratio (E2 / E1), the fiber diameter (E1) of the constituent fibers of the first fiber layer M1 is preferably 5 μm or more, more preferably 6 μm or more, and even more preferably 7 μm or more, from the viewpoint of diffusion from M1 to M2. From the viewpoint of skin feel, the fiber diameter (E1) of the constituent fibers of the first fiber layer M1 is preferably 80 μm or less, more preferably 70 μm or less, and even more preferably 60 μm or less. The fiber diameter mentioned above refers to the average fiber diameter of the constituent fibers in the second fiber layer M2 and the first fiber layer M1.

[0030] (Method for measuring the average fiber diameter of constituent fibers in the second fiber layer M2 and the first fiber layer M1) The fiber diameter can be measured by observing the cross-section of the fiber layer using the following method. The area to be measured (e.g., the first fiber layer M1) is frozen in an unloaded state using a cold spray or liquid nitrogen to fix its structure, and then the cross-section of the measurement area is exposed by cutting it in the thickness direction with a cutter blade. The cross-section is observed under magnification using a scanning electron microscope (JEOL Ltd. JCM-5100), and the magnification is adjusted to a level (100-500x) that allows for measurement of the fiber cross-section. Five observation photographs are taken in this state to obtain cross-sectional observation images. Next, the measurement position is set at the center of the thickness direction of the first fiber layer M1 and the second fiber layer M2, and the fiber diameter of 30 fibers per photograph is measured, and the arithmetic mean of these measurements is taken as the average fiber diameter of the present invention. If the fiber is not perfectly circular, the major axis is defined as the line segment connecting two points on the periphery of the cross-section and having the longest span of the cross-section, and the minor axis is defined as the line segment having the longest length perpendicular to the major axis. The lengths of the major axis and minor axis of each fiber are then analyzed and calculated using image analysis software, etc., to measure the lengths of the major axis and minor axis of each fiber. The arithmetic mean of the major axis length and minor axis length of a single fiber is taken as the fiber diameter of each fiber, and the arithmetic mean of 30 of these fiber diameters is taken as the average fiber diameter of the fibers in the present invention. If the nonwoven fabric to be measured is incorporated into a sanitary product such as an absorbent article, spray the sanitary product with a cold spray to solidify the hot melt adhesive, and then carefully peel off the nonwoven fabric to be measured. This method is common to other measurements specified herein.

[0031] In the nonwoven fabric 10, from the same viewpoint as the above fiber diameter, it is preferable that the fiber density (F2) of the second fiber layer M2 is higher than the fiber density (F1) of the first fiber layer M1. The ratio (F2 / F1) of the fiber density (F2) of the second fiber layer M2 to the fiber density (F1) of the first fiber layer M1 is preferably 1.0 or more, more preferably 0.98 or more, and still more preferably 0.95 or more. Also, from the viewpoint of increasing the absorption rate, the ratio (F2 / F1) is preferably 5 or less, more preferably 4 or less, and still more preferably 3 or less. Furthermore, within the range satisfying the above ratio (F2 / F1), from the viewpoint of increasing the capillary force, the fiber density (F2) of the second fiber layer M2 is preferably 10 fibers / mm 2 or more, more preferably 12 fibers / mm 2 or more, and still more preferably 15 fibers / mm 2 or more. From the viewpoint of increasing the absorption rate, the fiber density (F2) of the second fiber layer M2 is preferably 100 fibers / mm 2 or less, more preferably 80 fibers / mm 2 or less, and still more preferably 60 fibers / mm 2 or less. Also, within the range satisfying the above ratio (F2 / F1), from the viewpoint of enhancing the liquid diffusibility to the second fiber layer M2, the fiber density (F1) of the first fiber layer M1 is preferably 80 fibers / mm 2 or less, more preferably 60 fibers / mm 2 or less, and still more preferably 50 fibers / m 2 or less. From the viewpoint of making the texture feel better, the fiber density (F1) of the first fiber layer M1 is preferably 5 fibers / mm 2 or more, more preferably 8 fibers / mm 2 or more, and still more preferably 10 fibers / mm 2 or more. Note that the above fiber density means the average fiber density of the constituent fibers in the second fiber layer M2 and the first fiber layer M1.

[0032] (Measurement method for the average fiber density of the second fiber layer M2 and the first fiber layer M1) The average fiber density can be measured by observing the cross-section of the first fiber layer M1 or the second fiber layer M2 using the following method. The first fiber layer M1 is cut in the thickness direction so as to pass through the wall portion 1B in Figure 1, and the second fiber layer M2 is cut in a location other than the second opening portion 32. The cross-section is magnified and observed using a scanning electron microscope (JEOL Ltd. JCM-6000Plus (product name)), and the number of cut fiber cross-sections within a certain area of ​​the cross-section is counted. The magnification of the observation is adjusted to a magnification (30x to 100x) that allows for the measurement of approximately 30 to 60 fiber cross-sections. Next, 1 mm 2 Convert this to the number of fiber cross-sections per unit area, and use this as the fiber density (fibers / mm²). 2 The first fiber layer M1 is calculated by averaging the measurement results from 3 locations each in 1A and 1B (a total of 6 locations), and the second fiber layer M2 is calculated by averaging the measurement results from 3 random locations to obtain the average fiber density of the sample.

[0033] In the nonwoven fabric 10, the second opening 32 has a larger hole area and / or hole pitch than the first opening 31. As a result, the arrangement of the upper and lower through-holes 5 tends to be random on one side 10T of the nonwoven fabric 10. For example, some second openings 32 partially overlap with the first openings 31, while others overlap across a protrusion 1 and multiple first openings 31 surrounding it (for example, region J2 shown in Figure 1). This results in a random arrangement of the upper and lower through-holes 5 on one side 10T of the nonwoven fabric 10. Furthermore, variations in the degree of overlap between the second openings 32 and the protrusions 1 also tend to result in random hole areas in the upper and lower through-holes 5 through which the second openings 32 and the first openings 31 penetrate in the thickness direction. As a result, the upper and lower through-holes 5 are dispersed in the planar direction of the nonwoven fabric 10, making it possible to further improve liquid permeability to excretory fluids with various properties ranging from low viscosity to high viscosity.

[0034] From the above viewpoint, the ratio (Q2 / Q1) of the pore area (Q1) of the second opening 32 to the pore area (Q2) of the first opening 31 is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. Furthermore, from the viewpoint of increasing the absorption rate of low-viscosity excretory fluid, the ratio (Q2 / Q1) is preferably 60 or less, more preferably 50 or less, and even more preferably 40 or less. Furthermore, within the range that satisfies the above ratio (Q2 / Q1), the hole area (Q2) of the second opening 32 is 20 mm 2 The above is preferable, 25 mm 2 The above is more preferable, 30 mm 2 The above is even more preferable. The pore area (Q2) of the second opening 32 is 300 mm² from the viewpoint of increasing the absorption rate of low-viscosity wastewater. 2 The following is preferable: 250 mm 2 The following is more preferable: 200 mm 2 The following is even more preferable. Furthermore, within the range that satisfies the above ratio (Q2 / Q1), the hole area (Q1) of the first opening 31 is 15 mm 2 The following is preferable: 12 mm 2 The following is more preferable: 10 mm 2 The following is even more preferable: The pore area (Q1) of the first opening 31 is 1 mm² from the viewpoint of increasing the absorption rate of high-viscosity wastewater. 2 The above is preferable, 1.5 mm 2 The above is more preferable, 2 mm 2 The above is even more preferable. The hole area (Q2) of the second opening 32 and the hole area (Q1) of the first opening 31 are shown as the average value obtained by measuring at five locations using a microscope, as described above.

[0035] The aforementioned hole pitch refers to the pitch along the direction in which the convex portions 1 and bottom portions 2 are alternately arranged in the first fiber layer M1. The pitch also refers to the distance along the aforementioned direction from the end of the position with the largest hole width in one hole to the same position in an adjacent hole in the arrangement of holes along the aforementioned direction. If there are multiple directions in which the convex portions 1 and bottom portions 2 are alternately arranged, it is preferable that in at least one of these directions, the hole pitch of the second hole portion 32 is larger than that of the first hole portion 31 (for example, direction X shown in Figure 1).

[0036] From a viewpoint similar to that of pore area, the ratio (P2 / P1) of the opening pitch (P1) of the first opening 31 to the opening pitch (P2) of the second opening 32 is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 3.0 or more. Furthermore, from the viewpoint of the collection rate of low-viscosity discharged liquid, the ratio (P2 / P1) is preferably 10 or less, more preferably 8 or less, and even more preferably 5 or less. Furthermore, within the range that satisfies the above ratio (P2 / P1), the opening pitch (P2) of the second opening portion 32 is preferably 5 mm or more, more preferably 6 mm or more, and even more preferably 7 mm or more. From the viewpoint of increasing the absorption rate of high-viscosity waste liquid, the opening pitch (P2) of the second opening portion 32 is preferably 25 mm or less, more preferably 23 mm or less, and even more preferably 20 mm or less. Furthermore, within the range that satisfies the above ratio (P2 / P1), the hole pitch (P1) of the first opening portion 31 is preferably 15 mm or less, more preferably 12 mm or less, and even more preferably 10 mm or less. From the viewpoint of improving the appearance, the hole pitch (P1) of the first opening portion 31 is preferably 1.0 mmw or more, more preferably 1.5 mm or more, and even more preferably 2.0 mm or more.

[0037] (Method for measuring the opening pitch of the first opening 31 and the second opening 32) For example, using a KEYENCE VHX-6000 microscope (product name), observe at 20x magnification and use the length-measuring function to measure the distance along the aforementioned direction from the edge of the widest point of one opening to the same point in an adjacent opening in the arrangement of openings. However, if the pitch is large and does not fit within the microscope's field of view, measure visually using a metal ruler.

[0038] The basis weight of nonwoven fabric 10 is set at 20g / m² to improve cushioning and feel against the skin. 2 The above is preferable, 25 g / m 2 The above is more preferable: 30 g / m 2 The above is even more preferable. Furthermore, the basis weight of the nonwoven fabric 10 should be 150 g / m² from the viewpoint of improving the appearance when attached to the product. 2 The following is preferable: 90 g / m 2 The following is more preferable: 80g / m2 The following is even more preferable.

[0039] Nonwoven fabric 10: 4.9 mN / cm 2 (0.05 gf / cm 2 The thickness under load is preferably 1.0 mm or more, more preferably 1.2 mm or more, and even more preferably 1.5 mm or more, from the viewpoint of improving cushioning and feel. This thickness is 4.9 mN / cm 2 Measurements can be taken using a laser displacement meter or similar device under load. The above value is 4.9 mN / cm. 2 The load is calculated based on the assumption of fuzzing on the surface of the nonwoven fabric. For nonwoven fabric 10, the load is 4.9 mN / cm². 2 By keeping the thickness under load within the above range, the liquid return prevention performance is enhanced, making it less likely for the wearer's skin to get wet. Furthermore, the nonwoven fabric 10 has a load of 4.9 mN / cm². 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 hindering the wearer's comfortable use.

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

[0041] Preferably, the wall portion 1B of the first fiber layer M1 has a shape that extends perpendicularly to the direction along the plane of the other side 10B of the nonwoven fabric 10 (second fiber layer M2). As a result, the vertical wall portion 1B vertically connects the top portion 1A and the second fiber layer M2, and the soft fiber layer of the top portion 1A tends to remain supported by the elastic fiber layer of the wall portion 1B. This effect is enhanced by the longitudinal orientation of the fibers in the wall portion 1B. As a result, the thickness of the fiber layer of the convex portion 1 is felt through the top portion 1A, and the aforementioned cushioning effect is further enhanced. This makes it easier to obtain a softer tactile sensation. More specifically, this soft tactile sensation is felt as a gentle, reassuring thickness under light pressure, and under further pressure, the convex portion 1 deforms but does not easily sag, and is felt as an elastic, soft thickness. Due to this excellent cushioning effect, the texture of the uneven structure described above becomes even better. In addition, if the fibers of the wall portion 1B are longitudinally oriented, the effect of promoting liquid descent along those fibers is further enhanced, resulting in superior liquid absorption.

[0042] The "perpendicularity" of the wall portion 1B means not only 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 Figure 1 is exactly 90°, but also that it is between 60° and 120°. Being within this range, the wall portion 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 refers to the angle of intersection between the plane tangent to the surface of the other side 10B of the nonwoven fabric 10 and the extension line of the wall portion 1B. Specifically, as shown in Figure 1, in a cross-section in the thickness direction Z including the convex portion 1, the center line M of the width of the fiber layer of the wall portion 1B is used, and the straight line L tangent to the surface of the other side 10B of the nonwoven fabric 10 (second fiber layer M2) is used. This angle θ can be determined by observing the microscopic image of the cross-section obtained by the aforementioned microscope.

[0043] In the example shown in Figure 1, the wall portion 1B extends linearly between the top portion 1A and the second fiber layer M2, and the entire wall portion 1B is erected perpendicular to the second fiber layer M2. However, the configuration is not limited to this, and the wall portion 1B may include a portion that extends in a curved or wavy manner between the top portion 1A and the second fiber layer M2. In this case, the center line M is defined as the line connecting the boundary point between the top portion 1A and the wall portion 1B and the boundary point between the bottom portion 2 (or the second fiber layer M2) and the wall portion 1B, and the angle θ is determined accordingly. Furthermore, it is preferable that all of the multiple wall portions 1B extend perpendicularly to the second fiber layer M2, but some of the wall portions 1B may not extend perpendicularly to the plane of the other side 10B of the second fiber layer M2. In the latter case, from the viewpoint of making the aforementioned effects in the nonwoven fabric 10 even more effective, it is preferable that the number of perpendicular wall portions 1B be 60% or more of the wall portions 1B in the entire set of multiple protrusions 1.

[0044] In addition, it is preferable that in the first fiber layer M1, a hollow portion 1C is provided between the protrusion 1 and the second fiber layer M2. The hollow portion 1C is a space that is not substantially filled with fibers of the nonwoven fabric 10. Specifically, the fiber density determined by the method described later is 10 fibers / mm². 2 This means it is less than [a certain value]. A smaller fiber density in the hollow portion 1C is preferable. In the first fiber layer M1, the hollow portion 1C of the convex portion 1 opens to the second fiber layer M2 on the other side 10B.

[0045] (Method for measuring fiber density) The fiber density can be measured by observing a cross-section of the nonwoven fabric 10 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 (JEOL Ltd. JCM-6000Plus (product name)) is used to magnify and observe the cut surface including the hollow portion 1C, and count the cross-sections of the cut fibers within a certain area of ​​the cut surface including the hollow portion 1C. The magnification of the observation is adjusted to a magnification (30x to 100x) that allows for the measurement of approximately 30 to 60 fiber cross-sections. Next, 1 mm 2 Convert this to the number of fibers per unit area, and this becomes the fiber density (fibers / mm²). 2 The fiber density of the sample is calculated by averaging the results from the three measurement locations.

[0046] The presence of the hollow portion 1C inside the protrusion 1 further enhances the soft tactile feel of the protrusion 1, increasing the aforementioned cushioning properties and resulting in a more pleasant feel of the nonwoven fabric 10 against the skin. Furthermore, when the nonwoven fabric 10 is used as a surface sheet for absorbent articles or other components on the skin-facing side rather than the absorbent material, the presence of the hollow portion 1C blocks the liquid return path from the absorbent material, thereby improving the ability to prevent liquid return. In addition, the hollow portion 1C also serves as a primary storage space in case of excessive excretion, further increasing the liquid permeability of the nonwoven fabric 10 and further reducing the amount of liquid remaining on one side 10T.

[0047] Next, a specific example of the nonwoven fabric 10 shown in Figure 1 (nonwoven fabric 20) will be described with reference to Figures 2 to 5. The nonwoven fabric 20 has the same configuration as described for the nonwoven fabric 10. Note that the nonwoven fabric 20 shown in Figure 2 is shown from one side 20T where the first fiber layer M1 is located, and the outline of the second opening 32 of the second fiber layer M2 below is shown with a dashed line. In addition, the upper and lower through holes 5 are shown in black to clearly distinguish them from the concave parts 4 and to make the arrangement relationship easier to understand. The nonwoven fabric 20 shown in Figures 2 to 5 has, in a plan view from one side 20T, a plurality of ridges 11 extending in one direction Y as the aforementioned protrusions 1 in the first fiber layer M1, and arranged apart from each other in a direction X that intersects with the one direction Y. Hollow portions 11C are arranged inside the ridges 11 between them and the second fiber layer M2. One direction Y and the direction X intersecting with direction Y can be appropriately set on one side 20T of the nonwoven fabric 20 according to the purpose. For example, it is preferable that one direction Y and the direction X intersecting with direction Y are orthogonal to each other. When the nonwoven fabric 20 is used as a surface sheet or other component in an absorbent article, on the skin side of the absorbent, it is preferable that one direction Y is the longitudinal direction of the absorbent article, and the direction X intersecting with direction Y is the width direction of the absorbent article.

[0048] Multiple ridges 11 have equal heights along the direction of extension. "Equal heights" means that the heights measured using a microscope VHX900 (product name, manufactured by Keyence Corporation) are within the range of 0.8 times to 1.2 times the average measured value.

[0049] Each of the multiple ridges 11 comprises a top portion 11A and a wall portion 11B that supports the top portion 11A. The top portion 11A is a fibrous layer that comes into contact with the wearer's skin in an absorbent article, and the wall portion 11B is a fibrous layer that connects the top portion 11A and the second fibrous layer M2 in the thickness direction. That is, when the nonwoven fabric 20 is applied to an absorbent article, one side 20T becomes the skin-facing side, and the other side 20B becomes the non-skin-facing side. It is preferable that the fibers of the wall portion 11B are oriented vertically as described above. Furthermore, the wall portion 11B extends perpendicularly to the second fibrous layer M2 and perpendicularly connects the top portion 11A and the bottom portion 12 where the first opening portion 31 is located. The longitudinal orientation ratio, which indicates the longitudinal orientation of the fibers in this wall portion 11B, can be measured in a cross section perpendicular to the direction in which the ridge portion 11 extends (a cross section in the thickness direction at the position of the R1-R1 line or R2-R2 line along the direction X intersecting the one direction Y in Figure 2), as shown in Figures 3(A) and (B), based on the method described above (method for measuring the longitudinal orientation ratio of fibers in wall portion 1B). Furthermore, the aforementioned angle θ indicating the "perpendicularity" of the wall portion 11B refers to the interior angle of the angle formed between the center line M of the width of the fiber layer of the wall portion 11B and the straight line L tangent to the surface of the other side 20B of the nonwoven fabric 20 (second fiber layer M2), in a cross section perpendicular to the direction in which the ridge portion 11 extends (a cross section in the thickness direction at the position of the R1-R1 line or R2-R2 line along the direction X intersecting the direction Y in Figure 2). This angle θ can be determined by observing a microscopic image of the R1-R1 line or R2-R2 line cross section obtained by the aforementioned microscope.

[0050] The nonwoven fabric 20 has, as the aforementioned protrusions 1 in the first fiber layer M1, saddle portions 15 that connect adjacent ridge portions 11, 11, together with the aforementioned ridge portions 11. The saddle portions 15, like the ridge portions 11, protrude from the second fiber layer M2 to one side 20T of the nonwoven fabric 20 and are three-dimensional fiber layers erected in the thickness direction of the nonwoven fabric 20. More specifically, the saddle portion 15 comprises a top portion 15A on one side 20T and a wall portion 15B that supports the top portion 15A. It is preferable that the fibers of the wall portion 15B are oriented vertically as described above. Furthermore, the wall portion 15B extends perpendicularly to the second fiber layer M2. The term "perpendicular" is synonymous with the term "perpendicular" as defined in the aforementioned ridge portions 11. The longitudinal orientation ratio indicating the longitudinal orientation of the wall portion 15B in the saddle portion 15 and the "perpendicularity" of the wall portion 11B can be measured in the same manner as the measurement method described above for the wall portion 11B, for a cross section perpendicular to the direction of extension of the saddle portion 15 (a cross section in the thickness direction at the position of the R3-R3 line or R4-R4 line along one direction Y in Figure 2), as shown in Figures 4(A) and (B).

[0051] The above structure makes it difficult for the ridges 11 connected by the saddle portion 15 to come into close proximity, and prevents the ridges 11 from collapsing in one direction due to external forces such as pressing. In other words, the saddle portion 15 supports the ridges 11 from the side, improving the shape retention of the ridges 11. As a result, the thickness of the ridges 11 is more easily retained under load. For example, when the nonwoven fabric 20 is incorporated into an absorbent article as a surface sheet, even with the wearer's body pressure when wearing the absorbent article, the distance between the top portion 11A and the absorbent material on the other side (non-skin contact side) 20B is easily maintained, and liquid backflow to the other side (skin contact side) 20T is further reduced. Furthermore, the presence of the saddle portion 15 creates a damming effect on the excretory fluid between the ridge portions 11, 11, thereby improving the fluid flow prevention on one side (skin contact side) 20T of the nonwoven fabric 20.

[0052] The saddle portion 15 extends in a direction X that intersects with the direction Y from which the ridge portion 11 extends, in a plan view from one side 20T of the nonwoven fabric 20. The direction X from which the saddle portion 15 extends can be various directions as long as it connects adjacent ridge portions 11, and it is preferable that it is a direction perpendicular to the direction Y from which the ridge portion 11 extends. For example, it is preferable that the direction Y from which the ridge portion 11 extends is the longitudinal direction of the absorbent article, and the direction X from which the saddle portion 15 extends, intersecting the aforementioned direction, is the width direction of the absorbent article. Hereinafter, the direction Y and the direction X perpendicular to the direction Y will also be referred to as the extension direction Y of the ridge portion 11 and the extension direction X of the saddle portion 15. Furthermore, the planar shape of each saddle portion 15, as viewed from one side 20T, is not limited to a rectangle as shown in Figure 2, but can be various. For example, the planar shape of the saddle portion 15, as viewed from one side 20T, may be such that its width increases towards the ridge portion 11.

[0053] The saddle portions 15 are arranged in a plurality of band regions 16 that extend parallel to the ridge portions 11, between the ridge portions 11, 11 in a plan view of one side 20T of the nonwoven fabric 20. In each band region 16, the plurality of saddle portions 15 are arranged at intervals along the extension direction Y of the parallel ridge portions 11. The first opening portion 31 of the bottom portion 12 is located in the spaced-out portion of the saddle portions 15. That is, in each band region 16, the saddle portions 15 and the first opening portion 31 are arranged alternately. As a result, the first opening portion 31 is surrounded by the wall portion 11B of the ridge portion 11 and the wall portion 15B of the saddle portion 15. More specifically, the region surrounded by the plurality of ridge portions 11 and the plurality of saddle portions 15, which are three-dimensional fiber layers erected in the thickness direction, is a box-shaped or cylindrical recess, and the first opening portion 31 is located at the bottom of the recess. In the example shown in Figure 2, in a plan view from one side 20T of the nonwoven fabric 20, the ridges 11 and saddles 15 are arranged in a grid pattern, and the first openings 31 are scattered within the grid pattern in a grid-like arrangement. Note that the planar arrangement of the first openings 31 is not limited to this grid pattern, and can be various as long as it can achieve the aforementioned effect.

[0054] In the nonwoven fabric 20, the second openings 32 of the second fiber layer M2 are arranged at intervals along the extending direction X of the saddle portion 15, and further, rows of the second openings 32 are arranged at intervals along the extending direction Y of the ridge portion 11. The second openings 32 are offset in the extending direction X of the saddle portion 15 so that adjacent rows of the second openings 32 do not overlap in the extending direction Y of the ridge portion 11. That is, in the planar direction of the second fiber male M2, the second openings 32 are arranged in a staggered pattern. Note that the planar arrangement of the second openings 32 is not limited to this staggered pattern, and can be various as long as it can achieve the aforementioned effect.

[0055] As shown in Figure 2, each second opening 32 is positioned so as not to completely overlap with, or to encompass, the first opening 31 within the alternating arrangement region of the first opening 31 and the protrusion 1. Some of the second openings 32 constituting the upper and lower through-holes 5 span across the first opening 31, as well as the ridges 11 and saddles 15 which are the protrusions 1. As a result, multiple upper and lower through-holes 5 are arranged where the first opening 31 and the second opening 32 penetrate in the thickness direction, and multiple concave portions 4 are arranged where the first opening 31 and the second fiber layer M2 are laminated in the thickness direction, with the upper and lower through-holes 5 arranged within the region surrounded by the concave portions 4. This allows the aforementioned effects shown for the nonwoven fabric 20 to be widely expressed on the nonwoven fabric plane.

[0056] Furthermore, with the above arrangement, the number of upper and lower through-holes 5 per unit area is less than that of the concave portion 4, which can more effectively suppress liquid backflow. Furthermore, in the nonwoven fabric 20, the second opening 32 has a larger hole area and opening pitch than the first opening 31. The hole area and arrangement position of the upper and lower through-holes 5, through which the second opening 32 and the first opening 31 penetrate in the thickness direction, are random within the plane of the nonwoven fabric 20. As a result, the overlapping area of ​​the second opening 32, the first opening 31, the ridges 11, and the saddles 15 is formed to differ for each second opening 32, making the arrangement of the upper and lower through-holes 5 more random. This allows the aforementioned effects to be expressed more broadly and effectively within the plane of the nonwoven fabric 20.

[0057] Although the saddle portion 15 has a three-dimensional fiber structure similar to the ridge portion 11, it is preferable that it has a portion that is lower in height from the bottom portion 12 than the ridge portion 11, as shown in Figures 4(A) and (B) and Figure 5. This reduces the contact area with the skin on one side 20T of the nonwoven fabric 20, maintaining a pleasant feel against the skin, improving breathability, and further suppressing stuffiness between the fabric and the skin. The difference between the height H1 of the ridge portion 11 in the thickness direction and the height H2 of the saddle portion 15 in the thickness direction (H1-H2) is preferably 0.5 mm or more and 7 mm or less from the viewpoint of improving the above effect. The height H1 of the ridge portion 11 in the thickness direction is the distance in the thickness direction from the plane in contact with the surface of the other side 20B of the nonwoven fabric 20 (second fiber layer M2) to one side 20T of the top 11A of the ridge portion 11. The height H2 of the saddle portion 15 in the thickness direction is the distance in the thickness direction from the plane in contact with the surface of the other side 20B of the nonwoven fabric 20 (second fiber layer M2) to one side 20T of the lowest position of the top 15A of the saddle portion 15.

[0058] (Method for measuring the difference between the height H1 in the thickness direction of the ridge portion 11 and the height H2 in the thickness direction of the saddle portion 15) For the nonwoven fabric 20, as shown in Figures 4(A) and (B), a cross-section in the thickness direction along the extension direction of the band region 16 in which the saddle portions 15 are arranged, at the lowest position of the saddle portion 15 (the cross-section in the thickness direction at the positions of the R3-R3 line and R4-R4 line along one direction Y in Figure 2), is prepared and placed on a horizontal table so that the plane of the other side 20B of the second fiber layer M2 is in contact with it. The height H1 from the horizontal table to one side 20T of the top 11A of the ridge portion 11 and the height H2 from one side 20T of the top 15A of the saddle portion 15 are measured. From these measured values, the difference in height (H1-H2) is calculated. The aforementioned microscope can be used to measure the height from the horizontal table.

[0059] Furthermore, the saddle portion 15 is more preferably provided with a hollow portion 15C, as shown in Figures 4(A) and (B), from the viewpoint of improving the liquid absorbency of the nonwoven fabric 20 and the resulting surface dryness when the nonwoven fabric 20 is used as a surface sheet for an absorbent article, and from the viewpoint of further promoting drainage to the other side 20B. The definition and measurement method of this hollow portion 15C are the same as those for the hollow portion 11C in the ridge portion 11. This increases the liquid absorbency of the nonwoven fabric 20, promotes the diffusion of the drained liquid on the other side 20B, and further suppresses liquid retention on one side 20T. As a result, the amount of liquid remaining on the nonwoven fabric 20 is further reduced, and it becomes possible to further reduce the amount of liquid adhering to the skin.

[0060] Furthermore, as shown in Figure 5, in the cross-section of the saddle portion 15 in the direction of extension (the thickness direction cross-section at the position of the R5-R5 line along the direction X intersecting the direction Y in Figure 2), it is preferable that the hollow portion 15C of the saddle portion 15 is connected to and communicates with the hollow portion 11C of the ridge portion 11 at the intersection of the saddle portion 15 and the ridge portion 11. This allows liquid to flow vertically and horizontally between the hollow portion 15C and the hollow portion 11C on the other side 20B of the second fiber layer M2, thereby increasing the liquid absorption capacity of the absorbent fibers in the second fiber layer M2. In addition, the air permeability between the hollow portion 15C and the hollow portion 11C is increased, which helps to suppress stuffiness.

[0061] Next, preferred embodiments of the method for manufacturing the nonwoven fabric 20 will be described with reference to Figures 6 to 9. The manufacturing method described below can also be applied to the manufacturing method of the nonwoven fabric 10. The manufacturing method of this embodiment has the following five steps (hereinafter, each step may be referred to as step (I), step (II), step (III), step (IV), and step (V)). (I) A pressing step in which a first fiber web 100 is placed on a support 120 having an uneven shape with a plurality of protrusions 121 and recesses 125 between the protrusions 121, 121, and the first fiber web 100 is pressed along the recesses 125 by the pressing portion 131 of the pressing member 130 to shape it, and holes are made in the locations corresponding to the protrusions to form an uneven perforated fiber web 101 having an open surface on the side opposite to the support. (II) After removing the pressing member from the support, the first hot air W1 is blown onto the uneven perforated fiber web 101 to fuse the fibers together and obtain the uneven perforated nonwoven fabric 102. (III) A step of blowing a second hot air onto the second fiber web 103 to fuse the fibers together, thereby forming perforations that penetrate in the thickness direction at intervals in the planar direction, to obtain a flat perforated nonwoven fabric 104. (IV) A step of laminating the flat perforated nonwoven fabric 104 to the perforated side of the uneven perforated nonwoven fabric 102. (V) A heat fusion process in which a third hot air W3 is blown to fuse the fibers of the uneven perforated nonwoven fabric 102 and the flat perforated nonwoven fabric 104 together.

[0062] The first fiber web 100 described above is a precursor to the first fiber layer M1 in the nonwoven fabric 20 and contains thermoplastic fibers. The second fiber web is a precursor to the second fiber layer M2 in the nonwoven fabric 20 and contains thermoplastic fibers. The "fiber web" in the first fiber web 100 and the second fiber web 103 described above refers to a fiber aggregate in which constituent fibers, including thermoplastic fibers, are loosely intertwined without being fused and fixed, and which itself does not possess the shape-retaining properties of a sheet. In other words, it is a fiber aggregate before it is made into a nonwoven fabric. Therefore, the mobility between fibers in the fiber web is high, and the deformation of the first fiber web 100 in the pressing process is high. The first fiber web 100 and the second fiber web 103 are each supplied from a carding machine (not shown) to a predetermined thickness.

[0063] In step (I), as shown in Figure 6(A), the first fiber web 100 on the support 120 is directly pressed with mechanical pressure using the pressing member 130. This forms an uneven, perforated fiber web 101 that will become the first fiber layer M1 in the nonwoven fabric 20. Compared to pressing with non-mechanical pressure such as wind, this type of shaping allows for stronger fiber orientation and enables an orientation perpendicular to the nonwoven fabric plane. Furthermore, it does not require a very strong pressing force to create a large difference in the height of the unevenness formed on the first fiber web 100, allowing the first fiber web 100 to be shaped more easily. In addition, it can suppress fiber disorder and improve shapeability.

[0064] The support 120 is drum-shaped, for example, as shown in Figure 6, and has protrusions 121 on its drum surface, for example, as shown in Figure 6(A). On the drum surface of the support 120, for example, as shown in Figure 7, a plurality of protrusions 121 are arranged at intervals in one direction (first direction D1) and in a direction perpendicular to it (second direction D2). A plurality of rows of protrusions 121A, each consisting of multiple protrusions 121 arranged in the first direction D1, are arranged spaced apart from each other in the second direction D2. The protrusions 121 have a spire portion 122 at their tip. This spire portion 122 forms the first opening portion 31 at the bottom portion 12 of the first fiber layer M1. The planar shape of the spire portion 122 of the projection 121, as viewed from the side, is not limited to a rectangle as shown in Figure 7, but can take various forms. For example, it may be circular, elliptical, rhombus, or the like. The recess 125 has a first recess 125A extending in a first direction D1 between rows of protrusions 121A, 121A, and a second recess 125C located between protrusions 121, 121 in row of protrusions 121A. The second recess 125C is connected to the adjacent first recess 125A and extends intermittently in a second direction D2 via the first recess 125A.

[0065] In the support 120, multiple protrusions 121 are arranged corresponding to the positions where the first opening 31 of the bottom 12 of the first fiber layer M1 in the nonwoven fabric 20 is formed. The second recess 125C between the protrusions 121, 121 in the row of protrusions 121A is located where the saddle portion 15 of the first fiber layer M1 in the nonwoven fabric 20 is formed. That is, the row of protrusions 121A is located where the band region 16 between the ridges 11, 11 in the first fiber layer M1 of the nonwoven fabric 20 is formed. The first recess 125A is located where the ridges 11 of the first fiber layer M1 of the nonwoven fabric 20 are formed. The bottom of each recess 125 is designed to allow hot air to blow through, and for example, multiple holes are provided (not shown).

[0066] The pressing member 130 is, for example, a roll-shaped member as shown in Figure 6, and has pressing portions 131 on its circumferential surface, for example, as shown in Figure 6(A). On the circumferential surface of the pressing member 130, for example, as shown in Figure 8, multiple pressing portions 131 are arranged in a first direction D1 and spaced apart in a second direction D2. The spaces between the pressing portions 131 are recesses 132 that are continuous in the first direction D1. The pressing portion 131 of the pressing member 130 corresponds to the first recess 125A of the support 120. The recess 132 of the pressing member 130 corresponds to the row of protrusions 121A of the support 120. The bottom of the recess 132 of the push-in member 130 has a structure that allows hot air to blow through, and for example, multiple holes are provided (not shown).

[0067] The height of the push-in portion 131 of the push-in member 130 is preferably 1 mm or more in length so that it can be sufficiently inserted between the protrusions 121 of the support 120.

[0068] The first direction D1 and the second direction D2 in the support 120 and the pressing member 130 are preferably the machine flow direction (MD) and the cross direction (CD) perpendicular to the machine flow direction in the manufacturing process. The machine flow direction and the width direction in the manufacturing process preferably correspond to one direction Y and one direction X intersecting Y in the nonwoven fabric 20, and preferably correspond to the longitudinal direction and the width direction in the absorbent article containing the nonwoven fabric 20. However, the first direction D1 and the second direction D2 are not limited to these.

[0069] In step (I), the projection 121 of the support 120 is inserted into the recess 132 of the pressing member 130. The pressing portion 131 of the pressing member 130 is inserted into the first recess 125A of the support 120 (Figures 6(A) and 9). This pressing action between the support 120 (Figure 7) and the pressing member 130 (Figure 8) allows for the formation of the uneven shape of the first fiber layer M1. At the position of the first recess 125A of the support 120, the first fiber web 100 is pressed and shaped by the pressing portion 131 of the pressing member 130. This portion becomes the ridge portion 11 in the first fiber layer M1 of the nonwoven fabric 20. At this time, the fibers of the first fiber web 100 are shaped between the projection 121 of the support 120 and the pressing portion 131 of the pressing member 130 into a vertically upright shape along the thickness direction. Since the shaped fibers are highly mobile and not fused, they are oriented in the thickness direction. This portion becomes the wall portion 11B of the ridge portion 11 in the first fiber layer M1 of the nonwoven fabric 20. Meanwhile, at the position of the projection 121 of the support 120, the fibers of the first fiber web 100 are pushed up to the bottom of the recess 132 of the pushing member 130, creating an opening. This portion becomes the first opening 31 at the bottom 12 of the first fiber layer M1 of the nonwoven fabric 20. The second recess 125C between the protrusions 121, 121 in the row of protrusions 121A of the support 120 corresponds to the recess 132 of the pressing member 130, so the pressing portion 131 does not fit into it. However, the pressing force of the pressing portions 131, 131 of the pressing member 130 acts on the fibers of the first fiber web 100 in the second recess 125C of the row of protrusions 121A on both sides. 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 pressing portions 131, 131 on both sides, pressed in the thickness direction, shaped in the thickness direction, and the orientation of the fibers changes. This portion becomes the saddle portion 15 in the first fiber layer M1 of the nonwoven fabric 20. The saddle portion 15 has a top portion 15A and a wall portion 15B, and the wall portion 15B is the same as the wall portion 11B of the ridge portion 11.

[0070] The height of the projection 121 of the support 120 and the height of the pressing portion 131 of the pressing member 130 are appropriately determined depending on the thickness of the nonwoven fabric being manufactured. For example, 2 mm or more is preferred, 3 mm or more is more preferred, 5 mm or more is even more preferred, 15 mm or less is preferred, 10 mm or less is more preferred, and 9 mm or less is even more preferred. Specifically, 2 mm to 15 mm is preferred, 3 mm to 10 mm is more preferred, and 5 mm to 9 mm is even more preferred.

[0071] Next, in step (II), after removing the pressing member 130 from the support 120, a first hot air W1 is blown onto the uneven perforated fiber web 101 to fuse the fibers together and obtain an uneven perforated nonwoven fabric 102 (Figure 6(B)). This uneven perforated nonwoven fabric 102 becomes the first fiber layer M1 of the nonwoven fabric 20. For example, after removing the pressing member 130 from the support 120, the uneven perforated fiber web 101 is rotated while being held on the support 120, and after passing the interlocking point between the support 120 and the pressing member 130, the first hot air W1 is blown onto the uneven perforated fiber web 101 in Figure 6(B) at the position of the hot air blowing section 140, which is step (II) described above. Preferably, the support 120 has a hot air suction section 141 at a position facing the hot air blowing section 140 inside the drum.

[0072] The temperature of the first hot air W1 is set to a temperature that can melt the thermoplastic fibers constituting the uneven perforated fiber web 101 and form fiber fusion portions at the intersections of the fibers. Considering the general 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 perforated fiber web 101, and more preferably 5°C to 50°C higher. From the viewpoint of effective fusion bonding, the wind speed of the first hot air W1 is preferably 2 m / s or more, and more preferably 3 m / s or more. Furthermore, from the viewpoint of making the apparatus 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.

[0073] Next, in step (III), a second hot air is blown onto the second fiber web 103 to fuse the fibers together, forming perforations that penetrate in the thickness direction at intervals in the planar direction, thereby obtaining a flat perforated nonwoven fabric 104 (not shown). This flat perforated nonwoven fabric 104 becomes the second fiber layer M2 of the nonwoven fabric 20. The temperature and wind speed of the second hot air at this time can be appropriately set within the same temperature and wind speed range as the first hot air W1. The perforations in the flat perforated nonwoven fabric 104 are formed by a method such as a rotary die cutter. It is preferable that the perforation area and / or perforation pitch of the perforations in the flat perforated nonwoven fabric 104 be larger than that of the perforations in the uneven perforated nonwoven fabric 102.

[0074] Next, in step (IV), the flat perforated nonwoven fabric 104 is laminated on the perforated side of the uneven perforated nonwoven fabric 102 (Figure 6(C)). For example, the uneven perforated nonwoven fabric 102 formed by blowing the first hot air W1 is separated from the drum surface of the support 120, and is conveyed downstream by a belt conveyor with the side on which the first perforations 31 are formed by the protrusions 121 facing upwards, and the flat perforated nonwoven fabric 104 is added to the perforated side and laminated.

[0075] Next, in step (V), a third hot air W3 is blown into the fusion furnace 170 to fuse the fibers of the uneven-perforated nonwoven fabric 102 and the flat-perforated nonwoven fabric 104 together (Figure 6(D)). This forms fused fiber portions at the intersections of the fibers of the uneven-perforated nonwoven fabric 102 and the flat-perforated nonwoven fabric 104, integrating them to obtain the nonwoven fabric 20. In this case, as shown in Figure 6(D), it is preferable to place the nonwoven fabric 102 with the uneven perforated side facing down on the net 180 and blow the third hot air W3 from the flat perforated nonwoven fabric 104 side to suppress fluffing on one side 20T.

[0076] The temperature of the third hot air W3 is preferably 0°C to 70°C higher than the melting point of the thermoplastic fibers constituting the uneven perforated nonwoven fabric 102 and the flat perforated nonwoven fabric 104, and more preferably 5°C to 50°C higher, considering the general fiber materials used in this type of product. The wind speed of the third hot air W3 is preferably 0.3 m / s or more, and more preferably 0.5 m / s or more, from the viewpoint of achieving better fusion between the uneven perforated nonwoven fabric 102 and the flat perforated nonwoven fabric 104. Furthermore, the wind speed of the third hot air W3 is preferably 50 m / s or less, and more preferably 30 m / s or less, from the viewpoint of preventing crushing by the hot air.

[0077] In the above manufacturing method, the indentation member 130 is not limited to having an indentation portion 131 that is continuous in the first direction D1, as shown in Figure 8. For example, the indentation portion 131 may be arranged in a grid pattern, with square-shaped recesses 132 between the grid-like indentation portions 131. In this case, the height of the formed saddle portion 15 will be higher, and the unevenness will be more pronounced.

[0078] In the method for manufacturing nonwoven fabric according to this embodiment, it is preferable to have a cooling step after blowing the first hot air W1. For example, as shown in Figure 6, 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 120 opposite each other at a position where the uneven perforated nonwoven fabric 102 obtained by blowing the first hot air W1 is along the outer circumference of the drum of the support 120. This makes it possible to keep the support 120 below a certain temperature and to peel off the obtained nonwoven fabric while maintaining its shape. As a result, in the manufactured nonwoven fabric 20, the shape of the wall portions 11B and 15B of the first fiber layer M1 is well maintained, and good cushioning properties, as well as liquid absorption properties and the resulting surface dryness, can be improved.

[0079] The thermoplastic fibers constituting the nonwoven fabric of the present invention can be any material commonly used for nonwoven fabrics, without any particular limitations. For example, they may be fibers made of a single resin component or composite fibers made of multiple resin components. Examples of composite fibers include core-sheath structures and side-by-side structures. When using composite fibers containing low-melting-point and high-melting-point components as thermoplastic fibers (for example, core-sheath composite fibers where the sheath is made of a low-melting-point component and the core is made of a high-melting-point component), it is preferable that the temperature of the hot air blown onto the fiber web during the manufacturing process is above the melting point of the low-melting-point component and below the melting point of the high-melting-point component. More preferably, the temperature is above 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 more above the melting point of the low-melting-point component and 20°C or more below the melting point of the high-melting-point component. Furthermore, from the viewpoint of elasticity, among core-sheath composite fibers, the more core components there are, the higher the elasticity. Therefore, it is preferable that the core component has a larger cross-sectional area ratio. A specific example of a core-sheath composite fiber where the sheath is made of a low-melting-point component and the core is made of a high-melting-point component is a core-sheath composite fiber where the sheath is made of polyethylene resin (hereinafter also referred to as PE) and the core is made of polyethylene terephthalate resin (hereinafter also referred to as PET). Furthermore, in a core-sheath composite fiber, if the resin component of the sheath has a lower glass transition temperature than the resin component of the core (hereinafter referred to as the low-glass transition temperature resin component; for example, if the core resin component is PET and the sheath resin component is PE), the recovery of the thickness of the nonwoven fabric can be further improved by reducing the mass ratio of the low-glass transition temperature resin component.

[0080] The nonwoven fabric of the present invention can be used for various purposes. For example, it can be used as a component of various absorbent articles. These various absorbent articles broadly include articles used to absorb bodily fluids, such as adult and infant diapers, sanitary napkins, panty liners, and incontinence pads.

[0081] An absorbent article having the nonwoven fabric of the present invention typically comprises a surface sheet, a back sheet, and a liquid-retaining absorbent interposed between the two sheets. In the absorbent article, the nonwoven fabric of the present invention can be suitably used as the surface sheet that comes into contact with the wearer's skin. [Examples]

[0082] The present invention will be described in more detail below based on examples, but the present invention is not to be construed as being limited thereto. In these examples, "parts" and "%" are both based on mass unless otherwise specified. "←" means that it has the same value as the column on the left.

[0083] (Example 1) Based on the manufacturing method shown in Figure 6, the nonwoven fabrics shown in Figures 2 to 5 were prepared under the following conditions, and these were used as the nonwoven fabric samples for Example 1. The first fiber web 100 uses a core-sheath type thermoplastic fiber with a fineness of 1.8 dtex (fiber diameter 16 μm) and a composition of polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio), with a basis weight of 30 g / m². 2 The second fiber web 103 was made using a core-sheath type thermoplastic fiber with a fineness of 1.8 dtex (fiber diameter 16 μm) (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) and a basis weight of 20 g / m². 2 It was made into a fiber web. In the support 120, the MD pitch and CD pitch of the projection 121 including the spire 122 were set to 5 mm and 5 mm respectively in a plan view, and the projection height including the spire 122 was set to 3.5 mm. The planar shape of the projection 121 from the spire 122 side was rhombic. The CD pitch of the indentation portion 131 of the indentation member 130 was set to 5 mm and the height of the indentation portion was set to 5 mm. The temperature of the first hot air W1 was set to 160°C and the wind speed to 10 m / s. As a result, an uneven perforated nonwoven fabric 102 (first fiber layer M1) having the first perforation portion 31 with the pore area and planar shape shown in Table 1 was fabricated. The temperature of the second hot air applied to the second fiber web 103 was set to 160°C and the wind speed to 5 m / s. The holes in the flat perforated nonwoven fabric 104 were formed by punching with a die. As a result, a flat perforated nonwoven fabric 104 (second fiber layer M2) having the second perforated portion 32 with the hole area and planar shape shown in Table 1 was produced. The temperature of the third hot air W3 applied to the laminate of the uneven perforated nonwoven fabric 102 and the flat perforated nonwoven fabric 104 was set to 139°C and the wind speed to 1 m / s. This produced the nonwoven fabric sample of Example 1 having the shape shown in Figures 2 to 5.

[0084] The nonwoven fabric sample of Example 1 prepared contained multiple concave portions 4 in which the first opening portion 31 and the second fiber layer M2 were laminated in the thickness direction, and multiple upper and lower through-hole portions 5 through which the first opening portion 31 and the second opening portion 32 penetrated in the thickness direction. The upper and lower through-hole portions 5 were located in the region sandwiched between the concave portions 4 in the planar direction of the nonwoven fabric sample, and the second opening portions 32 constituting the upper and lower through-hole portions 5 spanned the first opening portion 31 and the convex portion 1 of the first fiber layer M1. The number of upper and lower through-hole portions 5 per unit area was less than that of the concave portions 4. As shown in Table 1, the second opening portions 32 had a larger pore area and pore pitch than the first opening portion 31. Also, the nonwoven fabric sample of Example 1 was 4.9 mN / cm 2 (0.05 gf / cm 2 The thickness under load was 6 mm.

[0085] (Example 2) The nonwoven fabric sample for Example 2 was prepared in the same manner as in Example 1, except that the fiber diameter of the constituent fibers of the second fiber web 103 was 1.3 dtex (fiber diameter 14 μm) and the basis weight were as shown in Table 1.

[0086] (Example 3) Except for the hole area and planar shape of the second opening 32 being as shown in Table 1, the nonwoven fabric sample for Example 3 was prepared in the same manner as in Example 1.

[0087] (Example 4) The nonwoven fabric sample for Example 4 was prepared in the same manner as in Example 1, except that the opening pitch of the second opening portion 32 was as shown in Table 1.

[0088] (Comparative Example 1) A nonwoven fabric sample for Comparative Example 1 was prepared in the same manner as in Example 1, except that the second fiber layer M1 was not used.

[0089] (Comparative Example 2) A nonwoven fabric sample for Comparative Example 2 was prepared in the same manner as in Example 1, except that no openings were formed in the second fiber layer M2.

[0090] The following tests were performed using nonwoven fabric samples from each example and comparative example. (1) Tests using horse blood (1-1) Horse blood We used horse blood fibrous material from Japan Biomaterials Center Co., Ltd., adjusted to 24 cP. (1-2) Absorption time test using horse blood 30 g / cm² from the top of one side of each nonwoven fabric sample 2 The load was applied evenly, and a cross-sectional area of ​​850 mm was placed approximately in the center of each nonwoven fabric sample. 2 They placed the tube against the body and injected simulated urine through it. Three grams of the solution were injected twice, at three-minute intervals, and the time (in seconds) until the entire amount was absorbed was measured. "Total absorption" was defined as the point when no more horse blood was detected inside the tube. This procedure was repeated three times, and the average of the two measurements was used as the liquid absorption time (in seconds). A shorter liquid absorption time indicates that the liquid penetrates easily into the interior, i.e., the liquid has superior absorption properties. (1-3) Fluid spread test using horse blood After measuring the absorption time as described above, the area of ​​horse blood spread on each nonwoven fabric sample was measured and defined as the horse blood spread area. (2) Test using simulated urine (2-1) Pseudo-urine The composition used was 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, and water (96.886% by mass), adjusted to 1.2 cp. (2-2) Absorption time test using simulated urine For each nonwoven fabric sample, apply 20 g / cm² from the top of one side. 2 The load was applied evenly, and a cross-sectional area of ​​1000 mm was placed approximately in the center of each nonwoven fabric sample. 2A tube was placed over the body, and simulated urine was injected through it. 40g was injected three times at 10-minute intervals, and the time (in seconds) until the entire amount was absorbed was measured. "Total absorption" was defined as the point when no artificial urine was observed inside the tube. This procedure was repeated three times, and the average of the three measurements was taken as the liquid absorption time (in seconds). A shorter liquid absorption time indicates that the liquid penetrates the body more easily, i.e., that the liquid draw-in ability is superior. (2-3) Fluid spread test using simulated urine After measuring the absorption time as described above, the area of ​​the simulated urine spread on each nonwoven fabric sample was measured and defined as the area of ​​simulated urine spread.

[0091] [Table 1]

[0092] As shown in Table 1, the nonwoven fabric samples of each example showed shorter absorption times and suppressed liquid spreading compared to the nonwoven fabric samples of each comparative example, for both horse blood and simulated urine of varying viscosities. In other words, the nonwoven fabric samples of each example achieved high liquid permeability to excretory fluids with different properties, ranging from low to high viscosity. [Explanation of Symbols]

[0093] M1 First fiber layer M2 2nd fiber layer 1. Convex part 1A Top 1B Wall section 1C Hollow part 2 bottom 31 First hole 32 2nd hole 4 Concave part 5 Upper and lower through holes 10, 20 Nonwoven fabric 10T, 20T, one side 10B, 20B Other side

Claims

1. A nonwoven fabric having a first fiber layer and a second fiber layer laminated in the thickness direction, and each fiber layer including fiber fusion portions at the intersections of the fibers, The first fiber layer has an uneven structure comprising a plurality of protrusions and a plurality of bottoms provided between adjacent protrusions, each of the plurality of protrusions comprising a top and a wall supporting the top, and each of the plurality of bottoms is provided with a first opening that penetrates in the thickness direction. The second fiber layer is located on the side of the first fiber layer where the bottom portion is located. The second fiber layer has a plurality of second openings that penetrate in the thickness direction, which are intermittently arranged in the planar direction of the nonwoven fabric. The nonwoven fabric for absorbent articles comprises a plurality of concave portions in which the second fiber layer is laminated in the thickness direction relative to the first opening portion, and a plurality of upper and lower through-hole portions through which the first opening portion and the second opening portion penetrate in the thickness direction, wherein the upper and lower through-hole portions are located in a region sandwiched between the concave portions in the planar direction of the nonwoven fabric, and the second opening portions constituting the upper and lower through-hole portions span across the first opening portion and the convex portion of the first fiber layer.

2. The nonwoven fabric for absorbent articles according to claim 1, wherein the fiber diameter of the constituent fibers of the second fiber layer is smaller than the fiber diameter of the constituent fibers of the first fiber layer.

3. The nonwoven fabric for absorbent articles according to claim 1, wherein the fiber density of the second fiber layer is higher than the fiber density of the first fiber layer.

4. The nonwoven fabric for absorbent articles according to claim 1, wherein the second opening has a larger pore area and / or pore pitch than the first opening.

5. The nonwoven fabric for absorbent articles according to claim 1, wherein a hollow portion is disposed between the second fiber layer and the protrusions of the first fiber layer.

6. Weight: 20 g / m ２ 150g / m or more ２ The nonwoven fabric for absorbent articles according to claim 1, which is as follows:

7. 4.9 mN / cm ２ The nonwoven fabric for absorbent articles according to claim 1, wherein the thickness under load is 1.0 mm or more and 10 mm or less.

8. The nonwoven fabric for absorbent articles according to claim 1, wherein the fibers of the wall portion are oriented longitudinally.

9. An absorbent article having a nonwoven fabric for absorbent articles as described in any one of claims 1 to 8.

10. A pressing step is performed in which a first fiber web is placed on a support having an uneven shape with multiple protrusions and recesses between the protrusions, and the first fiber web is pressed along the recesses by the pressing portion of a pressing member to shape it, and holes are made in the locations corresponding to the protrusions, forming an uneven, perforated fiber web having an open surface on the side opposite to the support, After removing the pressing member from the support, a first hot air is blown onto the uneven perforated fiber web to fuse the fibers together and obtain an uneven perforated nonwoven fabric. A step to obtain a flat perforated nonwoven fabric is obtained by blowing a second hot air onto a second fiber web to fuse the fibers together, thereby forming perforations that penetrate in the thickness direction at intervals in the planar direction, A step of laminating the flat perforated nonwoven fabric onto the perforated side of the uneven perforated nonwoven fabric, A method for manufacturing a nonwoven fabric for absorbent articles, comprising a heat fusion step of blowing a third hot air to fuse the fibers of the uneven perforated nonwoven fabric and the flat perforated nonwoven fabric together.

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