Nonwoven fabric for absorbent article

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

[0002] Nonwoven fabrics are used in a variety of applications, such as components of absorbent articles such as diapers and sanitary napkins, and nonwoven fabrics having a variety of structures have been developed. For example, Patent Document 1 describes a nonwoven fabric having a concave-convex structure as a top sheet of an absorbent article. Patent Document 2 describes a nonwoven fabric having a structure in which a flat fiber layer is laminated on the concave side of a concave-convex fiber layer. Patent Document 3 describes a nonwoven fabric having a concave-convex upper layer and a flat lower layer laminated together as a top sheet of an absorbent article, with through holes in both layers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-467 A [Patent Document 2] JP 2019-44293 A [Patent Document 3] Patent Publication No. 2021-112421 Summary of the Invention [Problem to be solved by the invention]

[0004] The uneven structure as described above has the effect of enhancing the cushioning properties of the nonwoven fabric. In addition, when the nonwoven fabric is used as, for example, a top sheet of an absorbent article that comes into contact with the skin of a wearer, the excreted liquid can be easily moved in the thickness direction along the uneven structure, and the excreted liquid can be easily moved away from the skin of the wearer, thereby reducing residual liquid. However, excreted liquid absorbed by absorbent articles actually has various properties, particularly various viscosities, and its behavior in the absorbent article differs depending on the viscosity. For example, the lower the viscosity, the higher the mobility of the excreted liquid, and the easier it is to wet and spread in the planar direction. The higher the viscosity, the lower the mobility of the excreted liquid, and the easier it is to remain on the surface. In recent years, from the viewpoint of reducing the adhesion of excreted liquid to the skin and increasing the dryness of the surface, absorbent articles are required to exhibit excellent liquid absorption properties that can quickly transfer excreted liquid of various viscosities to the absorbent body. In this respect, there is room for further improvement in nonwoven fabrics used as components of absorbent articles.

[0005] In view of the above, the present invention relates to a nonwoven fabric for absorbent articles that can achieve high liquid permeability to excreted liquids with different properties, from low to high viscosity. [Means for solving the problem]

[0006] The present invention relates to a nonwoven fabric having a first fiber layer and a second fiber layer laminated in a thickness direction, each fiber layer including a fiber fusion portion at an intersection between fibers, the first fiber layer having an uneven structure including a plurality of protruding portions and a plurality of bottom portions provided between adjacent protruding portions, each of the plurality of protruding portions having an apex and a wall portion supporting the apex, each of the plurality of bottom portions having a first opening portion penetrating through in the thickness direction, the second fiber layer being provided on the side of the first fiber layer where the bottom portion is located, the second fiber layer having a plurality of protruding portions and a plurality of bottom portions provided between adjacent protruding portions, the first fiber layer having an uneven structure including a plurality of protruding portions and a plurality of bottom portions provided between adjacent protruding portions, each of the plurality of protruding portions having an apex and a wall portion supporting the apex, each of the plurality of bottom portions having a first opening portion penetrating through in the thickness direction, the nonwoven fabric includes a concave portion in which the second fiber layer is laminated in the thickness direction relative to the first opening, and a plurality of vertical through-hole portions in which the first openings and the second openings penetrate in the thickness direction, the vertical through-hole portions being located in an area sandwiched between the concave portions in the planar direction of the nonwoven fabric, and the second openings constituting the vertical through-hole portions are present across the first openings and the convex portions of the first fiber layer.

[0007] The present invention also provides a method for producing a porous fiber web by a pressing step of placing a first fiber web on a support having an uneven shape with a plurality of protrusions and recesses between the protrusions, pressing the first fiber web by a pressing part of a pressing member along the recesses to form a porous fiber web having an open surface on the opposite side to the support, and removing the pressing member from the support and then blowing a first hot air stream onto the porous fiber web. The present invention provides a method for producing a nonwoven fabric, comprising the steps of: a step of fusing fibers together to obtain an irregularly perforated nonwoven fabric; a step of blowing a second hot air onto a second fiber web to fuse the fibers together and form apertures penetrating in the thickness direction at intervals in the planar direction to obtain a flat perforated nonwoven fabric; a step of laminating the flat perforated nonwoven fabric on the aperture side of the irregularly perforated nonwoven fabric; and a heat fusing step of blowing a third hot air to fuse the fibers of the irregularly perforated nonwoven fabric and the flat perforated nonwoven fabric together. Effect of the Invention

[0008] The nonwoven fabric for absorbent articles of the present invention can realize high liquid permeability to excreted liquids having different properties, from low to high viscosity. Moreover, the manufacturing method of the nonwoven fabric for absorbent articles of the present invention can suitably manufacture the nonwoven fabric for absorbent articles of the present invention. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a schematic diagram of a preferred embodiment of a nonwoven fabric for absorbent articles according to the present invention. [Diagram 2] 1 is a plan view showing a specific example of a nonwoven fabric for absorbent articles according to the present embodiment, viewed from one side. [Diagram 3] 3A is a cross-sectional view taken along line R1-R1 of the nonwoven fabric for absorbent articles shown in FIG. 2, and FIG. 3B is a cross-sectional view taken along line R2-R2 of the nonwoven fabric for absorbent articles shown in FIG. [Figure 4] 3A is a cross-sectional view taken along line R3-R3 of the nonwoven fabric for absorbent articles shown in FIG. 2, and FIG. 3B is a cross-sectional view taken along line R4-R4 of the nonwoven fabric for absorbent articles shown in FIG. [Diagram 5] 3 is a cross-sectional view taken along the line R5-R5 of the nonwoven fabric for absorbent articles shown in FIG. 2. [Figure 6] FIG. 1 is an explanatory diagram showing a schematic diagram of a preferred embodiment of the method for manufacturing a nonwoven fabric for absorbent articles according to the present invention, in which (A) shows a pushing process, (B) shows a process for obtaining an unevenly apertured nonwoven fabric by a first hot air stream, (C) shows a process for laminating a flat apertured nonwoven fabric to an unevenly apertured nonwoven fabric, and (D) shows a process for integrating the unevenly apertured nonwoven fabric and the flat apertured nonwoven fabric by a third hot air stream. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 13 is a plan view showing a state in which the support body and the push-in member are combined. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 a nonwoven fabric. The nonwoven fabric 10 of this embodiment is a so-called thermal bonded nonwoven fabric having fiber fusion parts at the intersections of the fibers. For example, an air-through nonwoven fabric in which the fiber fusion parts are formed by an air-through method can be mentioned. Therefore, the nonwoven fabric 10 contains thermoplastic fibers as its constituent fibers. That is, the first fiber layer M1 and the second fiber layer M2, which constitute the nonwoven fabric 10, described below, contain thermoplastic fibers as their constituent fibers, and are nonwoven fabrics in which the fiber fusion parts are formed. The first fiber layer M1 and the second fiber layer M2 are integrated by the fiber fusion parts at the intersections of the fibers of each other.

[0011] The nonwoven fabric 10 of this embodiment has a first fiber layer M1 and a second fiber layer M2 laminated in the thickness direction Z as shown in FIG. 1. The nonwoven fabric 10 has a front and back surface, i.e., one side 10T and the other side 10B, with the first fiber layer M1 arranged on the one side 10T and the second fiber layer M2 arranged on the other side 10B. In the nonwoven fabric 10, for example, the one side 10T can be used as the surface. When the nonwoven fabric 10 is used as a member on the skin side of the absorbent body of an absorbent article, for example, as a top sheet, the one side 10T can be used as the skin side. In this case, the first fiber layer M1 is also referred to as the upper layer, and the second fiber layer M2 is also referred to as the lower layer. The one side 10T and the other side 10B refer to the front and back surfaces of the entire nonwoven fabric 10, and also refer to the front and back surfaces of the first fiber layer M1 and the second fiber layer M2. The thickness direction Z of the nonwoven fabric 10 also means the thickness direction Z of each of the first fiber layer M1 and the second fiber layer M2.

[0012] The first fiber layer M1 has a plurality of protruding portions 1 protruding toward one surface side 10T and a plurality of bottom portions 2 provided between adjacent protruding portions 1, 1. This gives the first fiber layer M1 an uneven structure in the thickness direction Z. The protruding portions 1 are three-dimensional fiber layers standing in the thickness direction Z of the first fiber layer M1, and are located higher on the one surface side 10T than the bottom portions 2. Each of the plurality of protruding portions 1 has an apex 1A and a wall portion 1B supporting the apex 1A.

[0013] The outer shape of one surface side 10T of the top portion 1A may be a flat surface or a curved surface. From the viewpoint of making the touch softer when it is used as the skin contact surface that comes into contact with the skin of the wearer, it is preferable that one surface side 10T of the top portion 1A is a dome-shaped or arch-shaped curved surface.

[0014] The fibers of the wall 1B are preferably oriented longitudinally with respect to the planar direction of the other side 10B of the nonwoven fabric 10 (second fiber layer M2). The planar direction of the nonwoven fabric 10 here means the direction along a plane (such as a flat base) that contacts the surface of the other side 10B of the nonwoven fabric 10 (second fiber layer M2). The longitudinal orientation of the fibers enhances the support force of the wall portion 1B in the thickness direction Z relative to the top portion 1A and the second fiber layer M2, and makes it easier for the thickness of the protruding portion 1 of the nonwoven fabric 10 to be maintained even under load. As a result, the nonwoven fabric 10 including the first fiber layer M1 and the second fiber layer M2 is more likely to retain its thickness, and, together with the elasticity due to the fiber structure of the fiber layers, has excellent cushioning properties. That is, the nonwoven fabric 10 has excellent softness when touching the skin. In addition, when the nonwoven fabric 10 is used as a member on the skin side of the absorbent body in an absorbent article, such as a top sheet, the action of permeation of bodily fluids is more likely to be sustained even under load, and liquid return (wetback) from the absorbent body to the skin side is suppressed.

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

[0016] (Method of measuring longitudinal orientation rate of fibers in wall portion 1B) As shown in FIG. 1, the wall portion 1B is measured in the following procedure. That is, the fiber layer cross section of the wall portion 1B defined in the cross section in the thickness direction of the nonwoven fabric 10, including the convex portion 1, the bottom portion 2, and the second fiber layer M2 of the first fiber layer M1, is observed at 35 times magnification with a scanning electron microscope (SEM). A square line with a side of 500 μm is added to the observed image as a reference line. Each side (reference line) of the square is defined as a side perpendicular to the thickness direction and the planar direction in the cross section of the nonwoven fabric 10. The total number of fibers passing through the reference line consisting of each side of the square is counted. The fibers passing through the square reference line perpendicular to the planar direction of the nonwoven fabric 10 are defined as the "number of horizontal fibers", and the fibers passing through the square reference line perpendicular to the thickness direction of the nonwoven fabric 10 are defined as the "number of vertical fibers". The longitudinal orientation rate is calculated as (number of vertical fibers) / (number of horizontal fibers+number of vertical fibers)×100=longitudinal orientation rate (%). Ten points are measured for each, and the average is taken as the value of the longitudinal orientation rate. The planar direction in the cross section of the nonwoven fabric 10 corresponds to a straight line L tangent to the surface of the other side 10B of the second fiber layer M2 shown in Fig. 1. The thickness direction Z corresponds to a direction perpendicular to the straight line L.

[0017] In the above-mentioned cross section in the thickness direction Z of the nonwoven fabric 10, including the protrusions 1 and the bottoms 2 of the first fiber layer M1, the fiber layer of the wall portion 1B can be divided by the following method. That is, a nonwoven fabric 10 having a cross section in the thickness direction Z including the top 1A and wall 1B of the first fiber layer M1 and the second fiber layer M2 is placed on the base of a microscope VHX6000 (product name, manufactured by Keyence Corporation) with the second fiber layer M2 (other surface side 10B) facing down. Next, a flat plate (e.g., a flat acrylic plate) is placed on the top 1A side (one surface side 10T) of the nonwoven fabric 10, and a pressure of 4.9 mN / cm is applied. 2A load of 10 ...

[0018] The bottom portion 2 of the first fiber layer M1 is located at the bottom (including the base portion 1D) of a recess recessed into the other surface side 10B between the protrusions 1, 1, and is adjacent to the second fiber layer M2. Each of the multiple bottom portions 2 has a first opening 31 penetrating in the thickness direction Z. The penetration of the first opening 31 here means that, when focusing on the first fiber layer M1, a portion of the first fiber layer M1 where no constituent fibers are arranged penetrates both sides of the first fiber layer M1 in the thickness direction Z.

[0019] Unlike the fine holes formed between the fibers, the first openings 31 are holes intentionally formed by processing the first fiber layer M1, and have a hole area far larger than the fine holes formed between the fibers. In FIG. 1, the entire bottom 2 except for the base 1D is shown as the opening 3, but the size of the first openings 31 can be appropriately selected depending on the width of the bottom 2, etc. For example, in the first fiber layer M1, instead of the entire bottom 2 except for the base 1D being the opening 3, a fiber layer extending from the base 1D may be present around the first openings 31. At least 1.0 mm 2 It is preferable that the first opening 31 has a hole area of ​​at least 10 mm. The size of the first opening 31 can be measured using the above-mentioned microscope. Specifically, the area of ​​each of the first openings 31 is measured at 10 points using the microscope, and the average value of the areas is regarded as the hole area of ​​each opening.

[0020] The planar shape of the first open pores 31 may be various in terms of enhancing liquid permeability, and examples thereof include a circle, an ellipse, a rectangle, and a diamond.

[0021] The first openings 31 are located in an area sandwiched between the walls 1B of adjacent protrusions 1. As a result, when the nonwoven fabric 10 is used as a member on the skin side of the absorbent body in an absorbent article, such as a topsheet, excreted liquid received from one surface side 10T can flow directly down to the first openings 31 along the walls 1B and be rapidly permeated into the absorbent body underneath. The first opening 31 may have its outer peripheral edge formed by the lower end of the wall 1B, or the constituent fibers of the first fiber layer M1 (constituent fibers of the bottom 2) may be arranged between the lower end of the wall 1B and the outer peripheral edge of the first opening 31. When the constituent fibers of the first fiber layer M1 are present between the lower end of the wall portion 1B and the outer peripheral edge of the first openings 31 (when the first openings 31 are in part of the bottom portion 2 and the constituent fibers of the first fiber layer are present in the bottom portion 2), the distance in the planar direction between the lower end of the wall portion 1B and the outer peripheral edge of the first openings 31 is preferably 0.5 mm or less from the viewpoint of the above-mentioned liquid permeability. Note that when the 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 disposed on the side where the bottom of the first fiber layer M1 is located. The second fiber layer M2 has a plurality of second openings 32 penetrating in the thickness direction Z and arranged intermittently in the planar direction of the nonwoven fabric 10. 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 far larger than the diameter of the minute holes formed between the fibers. The penetration of the second openings 32 means that, when focusing on the second fiber layer M2, a 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 second open pores 32 may have various planar shapes from the viewpoint of improving liquid permeability, and examples of such shapes include a circle, an ellipse, a rectangle, and a diamond. The second fiber layer M2 preferably has a flat surface, unlike the first fiber layer M1. It is preferable that at least the other surface 10B is a flat surface, and it is more preferable that both surfaces are flat. In this case, the flat surface means that the surface is not textured except for the openings and their edges.

[0023] In the laminated structure of the first fiber layer M1 and the second fiber layer M2 described above, the nonwoven fabric 10 has a plurality of recessed portions 4 in which the first openings 31 and the second fiber layer M2 are laminated in the thickness direction Z, and a plurality of vertical through holes 5 in which the first openings 31 and the second openings 32 penetrate in the thickness direction Z. The first openings 31 constituting the recessed portions 4 and the vertical through holes 5 are located at the bottom 2 as described above. In other words, the recessed portions 4 and the vertical through holes 5 are located at the bottom 2 between the protruding portions 1 in the first fiber layer M1. The vertical through-holes 5 are located in a region sandwiched between the recesses 4 in the planar direction X of the nonwoven fabric 10 (for example, regions J1 and J2 shown in FIG. 1). In this arrangement, the vertical through-holes 5 and the recesses 4 are adjacent to each other but are separated by the protrusions 1 and their walls 1B in the first fiber layer M1. Therefore, the nonwoven fabric 10 has a structure that makes it easier for excreted liquid to move from one surface side 10T to the other surface side 10B rather than diffusing it in the planar direction X. The recesses 4 and the vertical through-holes 5 are adjacent to each other through the protrusions 1 and are mixed together, so that the recesses 4 and the vertical through-holes 5 can cooperate to improve the liquid permeability in the thickness direction Z of the nonwoven fabric 10. Therefore, when excreted liquid is received on one surface side 10T of the nonwoven fabric 10, the excreted liquid is lowered from the top 1A of the protrusion 1 along the wall 1B to suppress liquid diffusion in the planar direction X. This action is strengthened by the vertical orientation of the fibers of the wall 1B. At this time, the recessed portion 4 and the vertical through-hole portion 5 act on the lowered excreted liquid as follows. That is, the recessed portion 4 can quickly draw low-viscosity excreted liquid (or its components; for example, thin menstrual blood, urine) to the other surface side 10B by the capillary force of the constituent fibers of the second fiber layer M2. The vertical through-hole portion 5 can quickly permeate high-viscosity excreted liquid (or its components; for example, thick menstrual blood, loose stool) directly to the other surface side 10B in addition to the above-mentioned low-viscosity excreted liquid. The mixture of such recessed portions 4 and vertical through-hole portions 5 allows excreted liquids ranging from low to high viscosity to be quickly permeated and absorbed even in a mixed state. For example, it can simultaneously and rapidly permeate and absorb urine and loose stool. Note that the above low viscosity means 5 cp or less, and high viscosity means 10 cp or more. Furthermore, as described above, in the recessed portion 4, the first openings 31 of the first fiber layer M1 are covered with the constituent fibers of the second fiber layer M2. By arranging the vertical through-holes 5 in the region sandwiched between the recessed portions 4, the capillary force of the constituent fibers of the second fiber layer M2 can extend not only to the recessed portion 4 but also to the vertical through-holes 5. This increases the liquid permeation speed (liquid absorption speed) of various viscosities in the nonwoven fabric 10 and further suppresses liquid diffusion on the one surface side 10T compared to when the vertical through-holes 5 are arranged alone. In addition, the above-mentioned capillary force enhances the suppression of the excreted liquid that has once permeated and is on the other surface side 10B from returning to the one surface side 10T.

[0024] In addition, in the nonwoven fabric 10, the second openings 32 constituting the vertical through-holes 5 are present across the first openings 31 and the convex portion 1 of the first fiber layer M1. That is, at the position of the vertical through-holes 5, the opening of the other surface side 10B is larger than the opening of the liquid intake on the one surface side 10T. This makes it easier for the excreted liquid that permeates from the one surface side 10 through the vertical through-holes 5 to diffuse on the other surface side 10B, thereby increasing the liquid permeation rate in the nonwoven fabric 10 and suppressing liquid diffusion and liquid residue on the one surface side 10T. This is particularly effective in improving the liquid permeation rate for high-viscosity excreted liquid that tends to remain in one place. Furthermore, the second openings 32 constituting the vertical through-holes 5 extend beyond the position of the vertical through-holes 5 in the planar direction of the other surface side 10B to a position overlapping with the convex portion 1. Therefore, the second openings 32 easily draw in liquid from the concave portion 4 adjacent to the convex portion 1 at the extension destination. Therefore, even if there is high-viscosity excreted liquid in the recessed portion 4, it can easily migrate to the second openings 32. Even if the amount of low-viscosity excreted liquid drawn into the recessed portion 4 becomes excessive, it can easily migrate from the constituent fibers of the second fiber layer M2 constituting the recessed portion 4 to the adjacent second openings 32. In this way, the liquid can be accommodated between the second openings 32 and the constituent fibers of the second fiber layer M2 on the other surface side 10B of the nonwoven fabric 10. This allows the nonwoven fabric 10 to quickly permeate excreted liquids of a wider variety of viscosities by increasing the liquid permeation speed.

[0025] From the viewpoint of the above-mentioned action, in the planar direction X of the nonwoven fabric, the vertical through-hole portion 5 is preferably located in a region surrounded on its front, rear, left and right sides by the concave portions 4. More specifically, it is preferable that the front, rear, left and right sides of the vertical through-hole portion 5 are surrounded by the convex portions 1, and the convex portions are further surrounded by the concave portions 4. In addition, in the region sandwiched between the recessed portions 4, there may be one vertical through-hole portion 5 (for example, region J1 shown in FIG. 1) or multiple vertical through-hole portions 5 (for example, region J2 shown in FIG. 1). When multiple vertical through-hole portions 5 are present, it is preferable that a convex portion 1 is interposed between adjacent vertical through-hole portions 5, 5, as in region J2 shown in FIG. 1. The vertical through-hole portion 5 may be smaller than or the same as the hole area of ​​the first opening portion 31, and from the viewpoint of absorbing high-viscosity discharged liquid, it is preferable that the hole area of ​​the vertical through-hole portion 5 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 member on the skin side of the absorbent body in an absorbent article, such as a top sheet, the nonwoven fabric 10 can achieve high liquid permeability to a variety of excreted liquids with different properties, from low to high viscosity, regardless of the viscosity of the excreted liquid. Furthermore, the nonwoven fabric 10 has excellent cushioning properties due to the protrusions 1 supported by the walls 1B, in which the fibers are preferably oriented vertically, on one surface side 10T, and has a comfortable thickness and excellent softness against the skin. In addition, the presence of the vertical through-holes 5 in the area sandwiched between the recesses 4 increases the visibility of the open structure, and the high liquid absorbency can be strongly appealed to consumers.

[0027] The area ratio of the vertical through holes 5 in the area of ​​the entire nonwoven fabric 10 viewed in a plane is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more, from the viewpoint of enhancing the above-mentioned liquid permeability. The area ratio is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less, from the viewpoint of suppressing liquid return. The area of ​​the vertical through holes 5 can be measured using the above-mentioned microscope. In this measurement, the nonwoven fabric 10 is first cut into a size of 50 mm x 50 mm, and the total area of ​​the vertical through holes 5 in that region is measured. Then, the area ratio of the vertical through holes 5 in the area of ​​the entire nonwoven fabric 10 viewed in a plane is calculated using the following formula. Area ratio (%) of the vertical through holes 5 in the area of ​​the entire nonwoven fabric 10 viewed in a plane=(total area of ​​the vertical through holes 5) / (50×50)×100 The plan view of the entire nonwoven fabric 10 is taken from one surface side 10T.

[0028] The area ratio of the recessed portions 4 to the area of ​​the entire nonwoven fabric 10 viewed in a plan view is preferably 3% or more, more preferably 4% or more, and even more preferably 5% or more, from the viewpoint of enhancing the above-mentioned liquid permeability. Moreover, the area ratio is preferably 35% or less, more preferably 30% or less, and even more preferably 25% or less, from the viewpoint of suppressing liquid return. The area of ​​the recessed portions 4 can be measured by the same method as that for the area of ​​the above-mentioned vertical through-holes 5.

[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, and can further increase the permeability of excreted liquid (especially low-viscosity excreted liquid) through the recessed portion 4. In addition, the second fiber layer M2 has an increased attraction force for excreted liquid (especially high-viscosity excreted liquid) that has permeated through the vertical through-hole portion 5, making it easier to diffuse the excreted liquid on the other surface side 10B. From this viewpoint, the ratio (E2 / E1) of the fiber diameter (E2) of the fiber constituting the second fiber layer M2 to the fiber diameter (E1) of the fiber constituting 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. 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 of the above ratio (E2 / E1), the fiber diameter (E2) of the fibers constituting the second fiber layer M2 is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, from the viewpoint of enhancing the capillary force. The fiber diameter (E2) of the fibers constituting 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 lower layer. In addition, within the range satisfying 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 above fiber diameter means the average fiber diameter of the constituent fibers in the second fiber layer M2 and the first fiber layer M1.

[0030] (Method of measuring average fiber diameter of fibers constituting 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 part to be measured (for example, the first fiber layer M1) is frozen under no load using cold spray or liquid nitrogen to fix the structure, and then cut in the thickness direction using a cutter blade to expose the cross section of the measurement part. The cross section is observed under magnification using a scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.), and the magnification is adjusted to a value (100 to 500 times) at which the fiber cross section can be measured. Five observation photographs are taken in this state to obtain a cross-sectional observation photograph. Next, the central portion in the thickness direction of each of the first fiber layer M1 and the second fiber layer M2 is set as the measurement position, and the fiber diameters of 30 fibers per photograph are measured, and the arithmetic average value is the average fiber diameter of the present invention. When the fibers are non-circular, the line segment that connects two points on the periphery in the cross section and has the maximum across length of the cross section is set as the long axis, and the line segment that is perpendicular to the long axis and has the maximum length is set as the short axis, and the lengths of the long axis and the short axis are measured by analyzing and calculating them using image analysis software or the like, and the arithmetic average value of the long axis length and the short axis length of one fiber is set as the fiber diameter of each fiber, and the arithmetic average value of the fiber diameters of 30 fibers is set as the average fiber diameter of the fibers of the present invention. When the nonwoven fabric to be measured is incorporated in a sanitary product such as an absorbent article, the sanitary product is sprayed with cold spray to solidify the hot melt adhesive, and then the nonwoven fabric to be measured is carefully peeled off. This method is common to other measurements in this specification.

[0031] In the nonwoven fabric 10, from the same viewpoint as the fiber diameter described above, 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 even more preferably 0.95 or more. From the viewpoint of increasing the absorption rate, the ratio (F2 / F1) is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. Furthermore, within the range where the above ratio (F2 / F1) is satisfied, the fiber density (F2) of the second fiber layer M2 is set to 10 fibers / mm 2 More than 12 strands / mm is preferable. 2 More preferably, 15 lines / mm 2 From the viewpoint of increasing the absorption rate, the fiber density (F2) of the second fiber layer M2 is preferably 100 fibers / mm 2 Less than 80 strands / mm is preferable. 2 Less than 60 lines / mm is more preferable. 2 The following is even more preferred: In addition, in order to improve the liquid diffusibility into the second fiber layer M2, the fiber density (F1) of the first fiber layer M1 is set to 80 fibers / mm 2 Less than 60 strands / mm is preferable. 2 Less than 50 fibers / m is more preferable. 2 The fiber density (F1) of the first fiber layer M1 is more preferably 5 fibers / mm 2 More than 8 fibers / mm is preferable. 2 More preferably, 10 fibers / mm 2 The above is more preferable. 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] (Method of Measuring Average Fiber Density of Second Fiber Layer M2 and First Fiber Layer M1) The average fiber density can be measured by the following method by observing the cross section of the first fiber layer M1 or the second fiber layer M2. The first fiber layer M1 is cut in the thickness direction so as to pass between the wall portions 1B in FIG. 1, and the second fiber layer M2 is cut at a location other than the second opening portion 32. The cut surface is magnified and observed using a scanning electron microscope (JCM-6000Plus (product name) manufactured by JEOL Ltd.), and the number of cut fiber cross sections within a certain area of ​​the cut surface is counted. The magnification for the magnified observation is adjusted to a magnification (30x or more and 100x or less) that allows the measurement of approximately 30 to 60 fiber cross sections. Next, a 1mm 2 This is converted into the number of fiber cross sections per unit, and the fiber density (fibers / mm 2 The first fiber layer M1 is measured at three locations on each of 1A and 1B, for a total of six locations, and the second fiber layer M2 is measured at three random locations, and this is taken as the average fiber density of the sample.

[0033] In the nonwoven fabric 10, the second openings 32 have a larger hole area and / or hole pitch than the first openings 31. This makes it easier for the vertical through-holes 5 to be randomly arranged on one surface 10T of the nonwoven fabric 10. For example, the second openings 32 may partially overlap the first openings 31, or the second openings 32 may overlap the convex portion 1 and the multiple first openings 31 surrounding it (for example, the region J2 shown in FIG. 1), and the vertical through-holes 5 are randomly arranged on one surface 10T of the nonwoven fabric 10. In addition, the hole area of ​​the vertical through-holes 5 through which the second openings 32 and the first openings 31 penetrate in the thickness direction tends to be random due to variations in the degree of overlap between the second openings 32 and the convex portion 1. As a result, the vertical through-holes 5 can be dispersed in the planar direction of the nonwoven fabric 10, thereby further improving the liquid permeability to excreted liquids with various properties ranging from low viscosity to high viscosity.

[0034] From the above viewpoints, the ratio (Q2 / Q1) of the hole area (Q2) of the second hole portion 32 to the hole area (Q1) of the first hole portion 31 is preferably not less than 3, more preferably not less than 4, and even more preferably not less than 5. Moreover, from the viewpoint of increasing the absorption rate of low-viscosity excretory fluid, the ratio (Q2 / Q1) is preferably not more than 60, more preferably not more than 50, and even more preferably not more than 40. Furthermore, within the range where the above ratio (Q2 / Q1) is satisfied, the hole area (Q2) of the second opening 32 is 20 mm 2 More than 25mm is preferable. 2 More preferably, 30 mm or more 2 The aperture area (Q2) of the second opening 32 is preferably 300 mm 2 Less than 250mm is preferable 2 Less than 200mm is preferable. 2 The following is even more preferred: In addition, within the range where the above ratio (Q2 / Q1) is satisfied, the hole area (Q1) of the first opening 31 is 15 mm 2 Less than 12mm is preferable 2 Less than 10mm is preferable. 2 From the viewpoint of increasing the absorption rate of high-viscosity excretory liquid, the hole area (Q1) of the first opening 31 is preferably 1 mm 2 More than 1.5mm is preferable. 2 More preferably, 2 mm or more 2 The above is more preferable. As described above, the hole area (Q2) of the second opening 32 and the hole area (Q1) of the first opening 31 are measured at five locations using a microscope and are shown as the average value.

[0035] The above-mentioned hole pitch refers to the pitch along the direction in which the peaks 1 and bottoms 2 in the first fiber layer M1 are alternately arranged. The pitch also refers to the distance along the direction from the end of one hole at the position where the hole width is largest to the same position of another adjacent hole in the arrangement of the holes along the direction. When there are multiple directions in which the peaks 1 and bottoms 2 are alternately arranged, it is preferable that the second hole 32 has a larger hole pitch than the first hole 31 in at least one of the directions (for example, the direction X shown in FIG. 1).

[0036] From the same viewpoint as the hole area, the ratio (P2 / P1) of the hole pitch (P2) of the second hole sections 32 to the hole pitch (P1) of the first hole sections 31 is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 3.0 or more. From the viewpoint of the collection rate of the 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 satisfying the above ratio (P2 / P1), the opening pitch (P2) of the second openings 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 speed of high-viscosity excretory liquid, the opening pitch (P2) of the second openings 32 is preferably 25 mm or less, more preferably 23 mm or less, and even more preferably 20 mm or less. In addition, within the range satisfying the above ratio (P2 / P1), the opening pitch (P1) of the first openings 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 opening pitch (P1) of the first openings 31 is preferably 1.0 mm or more, more preferably 1.5 mm or more, and even more preferably 2.0 mm or more.

[0037] (Method of measuring the hole pitch of the first hole portion 31 and the second hole portion 32) For example, observation is performed at a magnification of 20 times using a microscope VHX-6000 (product name) manufactured by Keyence Corporation, and the distance along the aforementioned direction is measured from the end of the position where the hole width of one hole is the widest to the same position of another adjacent hole in the arrangement of the hole portions using the length measuring function. However, if the pitch is too large to fit within the angle of view of the microscope, the measurement is performed visually using a metal ruler.

[0038] The basis weight of the nonwoven fabric 10 is set to 20 g / m2 in order to improve cushioning and texture. 2 More than 25 g / m is preferable. 2 More preferably, 30 g / m 2 The weight per unit area of ​​the nonwoven fabric 10 is preferably 150 g / m2 or more from the viewpoint of improving the appearance when the product is worn. 2 Less than 90 g / m 2 Less than 80 g / m is more preferable.2 The following is even more preferred:

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

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

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

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

[0043] 1, the wall 1B extends linearly between the top 1A and the second fiber layer M2, and the entire wall 1B is provided perpendicular to the second fiber layer M2. However, this is not limited thereto, and the wall 1B may include a portion extending in a curved or wavy manner between the top 1A and the second fiber layer M2. In this case, the angle θ is specified by taking the line connecting the boundary point between the top 1A and the wall 1B and the boundary point between the bottom 2 (or the second fiber layer M2) and the wall 1B as the center line M. Although it is preferable that all of the walls 1B extend perpendicular to the second fiber layer M2, some of the walls 1B may not extend perpendicular to the plane of the other surface 10B of the second fiber layer M2. In the latter case, the number of perpendicular walls 1B is preferably 60% or more of the walls 1B in all of the protrusions 1, from the viewpoint of making the above-mentioned action of the nonwoven fabric 10 more effective.

[0044] In addition, it is preferable that the first fiber layer M1 has a hollow space 1C between the second fiber layer M2 and the inside of the protrusion 1. The hollow space 1C is a space that is not substantially filled with the fibers of the nonwoven fabric 10. Specifically, the hollow space 1C has a fiber density of 10 fibers / mm2 or less, which is determined by the method described later. 2 This means that the fiber density in the hollow portions 1C is less than that in the other surface side 10B. The lower the fiber density in the hollow portions 1C, the better. In the first fiber layer M1, the hollow portions 1C of the projections 1 are open to the side of the second fiber layer M2 on the other surface side 10B.

[0045] (Method of measuring fiber density) The fiber density can be measured by observing the cross section of the nonwoven fabric 10 and using the following method. The nonwoven fabric 10 is cut in the thickness direction so as to pass through the area to be measured (for example, between the wall portions 1B). A scanning electron microscope (JCM-6000Plus (product name) manufactured by JEOL Ltd.) is used to observe the cut surface including the hollow portion 1C under magnification, and the number of cut fiber cross sections within a certain area of ​​the cut surface including the hollow portion 1C is counted. The magnification for the magnified observation is adjusted to a magnification (30x or more and 100x or less) that allows the measurement of approximately 30 to 60 fiber cross sections. Next, a 1mm 2 This is converted into the number of fibers per unit, and the fiber density (fibers / mm 2 The results of the measurements at three locations shall be averaged to determine the fiber density of the sample.

[0046] The hollow portion 1C inside the protrusion 1 further improves the soft feel of the protrusion 1, further enhances the cushioning properties described above, and further improves the feel of the nonwoven fabric 10. Furthermore, when the nonwoven fabric 10 is used as a member on the skin side of the absorbent body, such as a top sheet of an absorbent article, the presence of the hollow portion 1C cuts off the liquid return path from the absorbent body, improving the prevention of liquid return. In addition, the hollow portion 1C also serves as a primary storage space in the event of excessive excretion, further improving the liquid permeability of the nonwoven fabric 10 and further reducing the amount of liquid remaining on one surface side 10T.

[0047] Next, a specific example (nonwoven fabric 20) of the nonwoven fabric 10 shown in Fig. 1 will be described with reference to Figs. 2 to 5. The nonwoven fabric 20 has the configuration described above for the nonwoven fabric 10. Note that the nonwoven fabric 20 shown in Fig. 2 is shown from one surface side 20T on which the first fiber layer M1 is disposed, and the outline of the second openings 32 of the underlying second fiber layer M2 is shown by a dashed line. The vertical through-holes 5 are shown filled in black to clearly distinguish them from the recessed portions 4 and to make it easier to understand their positional relationship. 2 to 5, in plan view from one surface side 20T, the first fiber layer M1 has a plurality of ribs 11 extending in one direction Y as the above-mentioned protrusions 1 and arranged at a distance from each other in a direction X intersecting the one direction Y. Inside the ribs 11, a hollow portion 11C is provided between the ribs 11 and the second fiber layer M2. The one direction Y and the direction X intersecting the one direction Y can be appropriately set according to the purpose on one surface side 20T of the nonwoven fabric 20. For example, the one direction Y and the direction X intersecting the one direction Y are preferably perpendicular to each other. When the nonwoven fabric 20 is used as a member on the skin side of an absorbent body, such as a topsheet in an absorbent article, it is preferable that the one direction Y is the longitudinal direction of the absorbent article, and the direction X intersecting the one direction Y is the width direction of the absorbent article.

[0048] The ridges 11 have the same height in the extension direction. The "same height" means that the height measured using a microscope VHX900 (product name, manufactured by Keyence Corporation) is within a range of 0.8 to 1.2 times the average measurement value.

[0049] Each of the ridges 11 includes a crest 11A and a wall 11B supporting the crest 11A. The crest 11A is a fiber layer that contacts the wearer's skin in an absorbent article, and the wall 11B is a fiber layer that connects the crest 11A and the second fiber layer M2 in the thickness direction. That is, when the nonwoven fabric 20 is applied to an absorbent article, the one surface side 20T becomes the skin side, and the other surface side 20B becomes the non-skin side. As described above, it is preferable that the fibers of the wall 11B are vertically oriented. In addition, the wall 11B extends perpendicular to the second fiber layer M2, and vertically connects the crest 11A and the bottom 12 in which the first openings 31 are arranged. The longitudinal orientation ratio, which indicates the longitudinal orientation of the fibers in this wall portion 11B, can be measured based on the above-mentioned method (method for measuring the longitudinal orientation ratio of fibers in wall portion 1B) in a cross section perpendicular to the extension direction of the ridge portion 11 (a thickness direction cross section at the position of line R1-R1 or line R2-R2 along direction X intersecting with direction Y in FIG. 2), as shown in Figures 3(A) and (B). 3(A) and 3(B), the angle θ indicating the "perpendicularity" of the wall portion 11B means the interior angle between the center line M of the width of the fiber layer of the wall portion 11B and a straight line L tangent to the surface of the other side 20B of the nonwoven fabric 20 (the second fiber layer M2) in a cross section perpendicular to the extending direction of the rib portion 11 (a thickness direction cross section at the position of the line R1-R1 or R2-R2 along the direction X intersecting with the one direction Y in FIG. 2). This angle θ can be obtained by observing a micrograph of the cross section along the line R1-R1 or R2-R2 obtained by the microscope described above.

[0050] The nonwoven fabric 20 has, as the above-mentioned convex portion 1 in the first fiber layer M1, the above-mentioned ridge portion 11 and the saddle portion 15 connecting the adjacent ridge portions 11, 11. The saddle portion 15, like the ridge portion 11, protrudes from the second fiber layer M2 to one surface side 20T of the nonwoven fabric 20, and is a three-dimensional fiber layer erected in the thickness direction of the nonwoven fabric 20. More specifically, the saddle portion 15 has a crest 15A on one surface side 20T and a wall portion 15B supporting the crest 15A. The fibers of the wall portion 15B are preferably vertically oriented as described above. In addition, the wall portion 15B extends perpendicular to the second fiber layer M2. The above-mentioned "perpendicular" has the same meaning as the "perpendicular" defined in the above-mentioned ridge portion 11. The longitudinal orientation rate indicating the longitudinal orientation of wall portion 15B in saddle portion 15 and the "vertical" of wall portion 11B can be measured in a cross section perpendicular to the extension direction of saddle portion 15 (thickness cross section at the position of line R3-R3 or line R4-R4 along one direction Y in FIG. 2) as shown in Figures 4(A) and (B) in the same manner as the measurement method described above for wall portion 11B.

[0051] The above structure makes it difficult for the ridges 11 connected by the saddle portion 15 to approach each other, and prevents the ridges 11 from falling in one direction due to an external force such as pressure. That is, the saddle portion 15 supports the ridges 11 from the side, improving the shape retention of the ridges 11. This makes it easier for the ridges 11 to maintain their thickness under load. For example, when the nonwoven fabric 20 is incorporated into an absorbent article as a top sheet or the like, even if there is body pressure from the wearer when wearing the absorbent article, the distance between the top portion 11A and the absorbent body on the other surface side (non-skin contact surface side) 20B is easily maintained, making it even harder for liquid to return to the one surface side (skin contact surface side) 20T. Furthermore, the presence of the saddle portion 15 acts to block excreted liquid between the ridges 11, 11, enhancing the ability to prevent liquid from flowing on one surface side (skin contact surface) 20T of the nonwoven fabric 20.

[0052] In a plan view from one surface side 20T of the nonwoven fabric 20, the saddle portion 15 extends in a direction X intersecting with the direction Y in which the rib portion 11 extends. The direction X in which the saddle portion 15 extends can be various directions as long as it connects adjacent ribs 11, and is preferably a direction perpendicular to the direction Y in which the rib portion 11 extends. For example, it is preferable that the direction Y in which the rib portion 11 extends is the longitudinal direction of the absorbent article, and the direction X in which the saddle portion 15 extends and intersects with the direction Y is the width direction of the absorbent article. Hereinafter, the direction Y and the direction X perpendicular to the direction Y are also referred to as the extension direction Y of the rib portion 11 and the extension direction X of the saddle portion 15. In addition, the planar shape of each saddle portion 15 as viewed from one surface side 20T is not limited to a rectangle as shown in Fig. 2, and may be various shapes. For example, the planar shape of the saddle portion 15 as viewed from one surface side 20T may be such that the width increases toward the ridge portion 11.

[0053] The saddle portions 15 are arranged in a plurality of band regions 16 extending parallel to the ribs 11 between the ribs 11, 11 in a plan view of one surface side 20T of the nonwoven fabric 20. In each band region 16, a plurality of saddle portions 15 are arranged at intervals along the extension direction Y of the ribs 11 running in parallel. The first opening 31 of the bottom portion 12 is located at the portion where the saddle portions 15 are spaced apart. That is, in each band region 16, the saddle portions 15 and the first opening 31 are alternately arranged. As a result, the first opening 31 is surrounded by the wall portion 11B of the rib portion 11 and the wall portion 15B of the saddle portion 15. More specifically, the region surrounded by the plurality of ribs 11 and the plurality of saddle portions 15, which are three-dimensional fiber layers erected in the thickness direction, is a box-shaped or cylindrical recess, and the first opening 31 is arranged at the bottom of the recess. 2, in a plan view from one surface side 20T of nonwoven fabric 20, ridge portions 11 and saddle portions 15 are arranged in a lattice pattern, and first openings 31 are arranged in a square pattern dotted within the lattice pattern. Note that the planar arrangement of first openings 31 is not limited to this square pattern, and various other arrangements are possible as long as the above-mentioned effect can be achieved.

[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 in the extending direction Y of the rib portion 11. In adjacent rows of the second openings 32, the second openings 32 are shifted in the extending direction X of the saddle portion 15 so that they do not overlap with each other in the extending direction Y of the rib portion 11. That is, the second openings 32 are arranged in a staggered manner in the planar direction of the second fiber layer M2. The planar arrangement of the second openings 32 is not limited to this staggered arrangement, and various arrangements can be used as long as they can achieve the above-mentioned effect.

[0055] As shown in FIG. 2, each second opening 32 is arranged so as not to completely overlap with the first opening 31 or to include the first opening 31 in the alternately arranged region of the first opening 31 and the convex portion 1. Some of the second openings 32 constituting the vertical through-holes 5 exist across the first opening 31 and the ridge portion 11 and the saddle portion 15 which are the convex portion 1. As a result, a plurality of vertical through-holes 5 through which the first openings 31 and the second openings 32 penetrate in the thickness direction, and a plurality of concave portions 4 in which the first openings 31 and the second fiber layer M2 are laminated in the thickness direction are arranged, and the vertical through-holes 5 are arranged within the region surrounded by the concave portions 4. As a result, the above-mentioned action shown for the nonwoven fabric 20 can be widely expressed on the plane of the nonwoven fabric.

[0056] Furthermore, with the above-mentioned arrangement, the number of vertical through-holes 5 per unit area is smaller than that of the recessed portions 4, so that liquid backflow can be more effectively suppressed. Furthermore, in the nonwoven fabric 20, the second openings 32 have a larger hole area and hole pitch than the first openings 31. The hole area and arrangement positions of the vertical through holes 5 through which the second openings 32 and the first openings 31 penetrate in the thickness direction are random in the plane of the nonwoven fabric 20. Therefore, the overlapping areas of the second openings 32 and the first openings 31, the ridges 11, and the saddles 15 are formed to differ for each second opening 32, and the arrangement of the vertical through holes 5 becomes more random. This allows the above-mentioned action to be exerted more widely and effectively in the plane of the nonwoven fabric 20.

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

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

[0059] In addition, it is more preferable that the saddle portion 15 has a hollow portion 15C as shown in Fig. 4 (A) and (B) from the viewpoint of increasing the liquid absorbency of the nonwoven fabric 20 and the resulting dryness of the surface when the nonwoven fabric 20 is used as a top sheet of an absorbent article, and from the viewpoint of further promoting drainage of liquid to the other surface side 20B. The definition and measurement method of this hollow portion 15C are the same as those of the hollow portion 11C in the ridge portion 11. This increases the liquid absorbency of the nonwoven fabric 20, promotes the diffusion of excreted liquid on the other surface side 20B, and further suppresses liquid retention on the one surface side 20T. As a result, the amount of liquid remaining in the nonwoven fabric 20 is further reduced, making it possible to further reduce the amount of liquid adhering to the skin.

[0060] Furthermore, as shown in the cross section in the extending direction of the saddle portion 15 in Fig. 5 (thickness direction cross section at the position of the R5-R5 line along the direction X intersecting with the one direction Y in Fig. 2), it is preferable that the hollow portion 15C of the saddle portion 15 is connected to 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 surface side 20B of the second fiber layer M2, thereby improving the liquid absorbency of the absorbent fiber of the second fiber layer M2. In addition, the breathability between the hollow portion 15C and the hollow portion 11C is improved, and stuffiness can be suppressed.

[0061] Next, a preferred embodiment of a method for producing the nonwoven fabric 20 will be described with reference to Figures 6 to 9. The production method described below can also be applied to a method for producing the nonwoven fabric 10. The manufacturing method of this embodiment includes 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 process in which a first fiber web 100 is placed on a support 120 having an uneven shape having a plurality of protrusions 121 and recesses 125 between the protrusions 121, 121, and the first fiber web 100 is pressed along the recesses 125 by a pressing portion 131 of a pressing member 130 to form a shape, and holes are opened at the locations corresponding to the protrusions, thereby forming an uneven open-hole fiber web 101 having an open surface on the opposite side to the support. (II) A step of removing the pushing member from the support, and then blowing a first hot air W1 onto the porous fibrous web 101 to fuse the fibers together to obtain a porous nonwoven fabric 102. (III) A step of blowing a second hot air stream onto the second fiber web 103 to fuse the fibers together and form apertures penetrating the second fiber web 103 in the thickness direction and spaced apart in the planar direction to obtain a flat apertured nonwoven fabric 104. (IV) A step of laminating the flat porous nonwoven fabric 104 on the porous surface side of the uneven porous nonwoven fabric 102. (V) A heat fusion step in which the fibers of the uneven porous nonwoven fabric 102 and the flat porous nonwoven fabric 104 are fused together by blowing a third hot air W3.

[0062] The first fibrous web 100 is a precursor of the first fibrous layer M1 in the nonwoven fabric 20 and contains thermoplastic fibers. The second fibrous web is a precursor of the second fibrous layer M2 in the nonwoven fabric 20 and contains thermoplastic fibers. The "fiber web" of the first fiber web 100 and the second fiber web 103 refers to a fiber assembly in which constituent fibers including thermoplastic fibers are not fused and fixed but are gently entangled, and which does not have the shape retention of a sheet by itself. In other words, it is a fiber assembly before being made into a nonwoven fabric. Therefore, the mobility between fibers in the fiber web is high, and the first fiber web 100 is highly deformable in the pushing process. Such first fiber web 100 and second fiber web 103 are each supplied from a carding machine (not shown) to a predetermined thickness.

[0063] In step (I), as shown in FIG. 6(A), the first fiber web 100 on the support 120 is directly pressed with mechanical pressure using a pressing member 130. This forms an uneven perforated fiber web 101 that will become the first fiber layer M1 in the nonwoven fabric 20. This type of shaping results in stronger fiber orientation and perpendicular orientation to the nonwoven fabric plane compared to pressing with non-mechanical pressure such as wind. Furthermore, it is not necessary to apply a large pressing force to increase the unevenness height difference formed on the first fiber web 100, and the first fiber web 100 can be shaped softly. Furthermore, fiber disorder can be suppressed to improve shaping properties.

[0064] The support 120 has a drum shape as shown in Fig. 6, for example, and has protrusions 121 as shown in Fig. 6(A) on the drum peripheral surface. On the drum peripheral surface of the support 120, a plurality of protrusions 121 are arranged at intervals in one direction (first direction D1) and a direction perpendicular thereto (second direction D2), as shown in Fig. 7, for example. A plurality of protrusions 121 are arranged in the first direction D1 to form a plurality of protrusion rows 121A, which are arranged at a distance from each other in the second direction D2. The protrusions 121 have peaks 122 at their tips. The peaks 122 form the first apertures 31 in the bottom portion 12 of the first fiber layer M1. The planar shape of the projection 121 as viewed from the spire 122 side is not limited to a rectangle as shown in Fig. 7, but may be various shapes, such as a circle, an ellipse, or a diamond. The recess 125 has a first recess 125A extending in the first direction D1 between the projection rows 121A, 121A, and a second recess 125C located between the projections 121, 121 in the projection row 121A. The second recess 125C is connected to the adjacent first recess 125A, and extends intermittently in the second direction D2 via the first recess 125A.

[0065] In the support 120, a plurality of protrusions 121 are arranged corresponding to positions where the first openings 31 are to be formed in the bottom portion 12 of the first fiber layer M1 of the nonwoven fabric 20. A second recess 125C between the protrusions 121, 121 in the protrusion row 121A is located at a position where the saddle portion 15 of the first fiber layer M1 of the nonwoven fabric 20 is formed. In other words, the protrusion row 121A is located at a position that becomes the band region 16 between the ribs 11, 11 in the first fiber layer M1 of the nonwoven fabric 20. The first recess 125A is located at a position that becomes the rib portion 11 in the first fiber layer M1 of the nonwoven fabric 20. The bottom of each recess 125 has a structure that allows hot air to pass through, and for example, has a plurality of holes (not shown).

[0066] The pushing member 130 is in the form of a roll as shown in Fig. 6, for example, and has a pushing portion 131 as shown in Fig. 6(A) on the roll peripheral surface. On the roll peripheral surface of the pushing member 130, a plurality of pushing portions 131 continuing in the first direction D1 are arranged at intervals in the second direction D2 as shown in Fig. 8, for example. Between the pushing portions 131, 131, a recess 132 continuing in the first direction D1 is formed. The pushing portion 131 of the pushing member 130 corresponds to the first recess 125A of the support body 120. The recess 132 of the pushing member 130 corresponds to the protrusion row 121A of the support body 120. The bottom of the recess 132 of the pushing member 130 has a structure that allows hot air to pass through, and for example, a plurality of holes (not shown) are provided therein.

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

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

[0069] In step (I), the protrusions 121 of the support 120 are inserted into the recesses 132 of the pushing member 130. The pushing parts 131 of the pushing member 130 are inserted into the first recesses 125A of the support 120 (FIGS. 6(A) and 9). This pushing between the support 120 (FIG. 7) and the pushing member 130 (FIG. 8) can favorably form the uneven shape of the first fiber layer M1. The first fiber web 100 is pressed into the first recess 125A of the support 120 by the pressing portion 131 of the pressing member 130 to form a shape. This portion becomes the rib portion 11 in the first fiber layer M1 of the nonwoven fabric 20. At this time, between the protrusion 121 of the support 120 and the pressing portion 131 of the pressing member 130, the fibers of the first fiber web 100 are shaped into a vertically standing shape along the thickness direction. The shaped fibers are not fused and have high mobility, so they are oriented in the thickness direction. This portion becomes the wall portion 11B of the rib portion 11 in the first fiber layer M1 of the nonwoven fabric 20. Meanwhile, at the positions of the protrusions 121 of the support 120, the fibers of the first fibrous web 100 are pushed up to the bottom of the recesses 132 of the pushing member 130 and opened. This portion becomes the first open portion 31 of the bottom portion 12 of the first fiber layer M1 of the nonwoven fabric 20. The second recess 125C between the protrusions 121, 121 in the protrusion row 121A of the support 120 corresponds to the recess 132 of the pushing member 130, so the pushing part 131 does not enter. However, the pushing force of the pushing parts 131, 131 of the pushing member 130 acts on both sides of the fibers of the first fiber web 100 in the second recess 125C of the protrusion row 121A. Due to this action, the fibers of the first fiber web 100 in the second recess 125C are stretched in the second direction D2 by the pushing parts 131, 131 on both sides and pushed in the thickness direction, so that the fibers are shaped in the thickness direction and the fiber orientation changes. This part becomes the saddle part 15 in the first fiber layer M1 of the nonwoven fabric 20. The saddle part 15 has an apex 15A and a wall part 15B, and the wall part 15B is similar to the wall part 11B of the ridge part 11.

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

[0071] Next, in step (II), after removing the pushing member 130 from the support 120, a first hot air W1 is blown onto the porous fiber web 101 to fuse the fibers together to obtain a porous nonwoven fabric 102 (FIG. 6(B)). This porous nonwoven fabric 102 becomes the first fiber layer M1 of the nonwoven fabric 20. For example, after removing the pushing member 130 from the support 120, the support 120 rotates while holding the porous fiber web 101, and after passing through the meshing portion between the support 120 and the pushing member 130, the first hot air W1 is blown onto the porous fiber web 101 at the position of the hot air blowing section 140 in FIG. 6(B), in the above step (II). The support 120 preferably 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 capable of melting the thermoplastic fibers constituting the porous fibrous web 101 and forming fused fiber portions at the intersections of the fibers. Considering typical fiber materials used in this type of product, the temperature is preferably 0°C to 70°C higher than the melting point of the thermoplastic fibers constituting the porous fibrous web 101, and more preferably 5°C to 50°C higher. From the viewpoint of effective fusion, the wind speed of the first hot air W1 is preferably 2 m / s or more, and more preferably 3 m / s or more. Also, from the viewpoint of making the device scale compact, the wind speed of the first hot air W1 is preferably 100 m / s or less, and more preferably 80 m / s or less.

[0073] Next, in step (III), a second hot air is blown onto the second fiber web 103 to fuse the fibers together, and apertures penetrating in the thickness direction are formed at intervals in the planar direction to obtain a flat apertured nonwoven fabric 104 (not shown). This flat apertured 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 range as that of the first hot air W1. The apertures in the flat apertured nonwoven fabric 104 are formed by a method such as a rotary die cutter. It is preferable that the apertures in the flat apertured nonwoven fabric 104 have a larger hole area and / or aperture pitch than the apertures in the uneven apertured nonwoven fabric 102.

[0074] Next, in step (IV), flat apertured nonwoven fabric 104 is laminated on the aperture side of unevenly apertured nonwoven fabric 102 (FIG. 6(C)). For example, unevenly apertured nonwoven fabric 102 formed by blowing first hot air W1 is separated from the drum circumferential surface of support 120 and transported downstream on a belt conveyer with the side on which first apertures 31 are formed by protrusions 121 facing up, and flat apertured nonwoven fabric 104 is joined and laminated on the aperture side.

[0075] Next, in step (V), a third hot air W3 is blown in the fusion furnace 170 to fuse the fibers of the unevenly perforated nonwoven fabric 102 and the flat perforated nonwoven fabric 104 together (FIG. 6(D)). As a result, fused fiber parts are formed at the intersections between the fibers of the unevenly perforated nonwoven fabric 102 and the flat perforated nonwoven fabric 104, and the fabrics are integrated to obtain the nonwoven fabric 20. At this time, as shown in Figure 6 (D), it is preferable to place the uneven porous nonwoven fabric 102 side down on the net 180 and blow the third hot air W3 from the flat porous nonwoven fabric 104 side, thereby suppressing fuzz on one surface side 20T.

[0076] Taking into consideration the typical fiber materials used in this type of product, the temperature of the third hot air W3 is preferably 0°C to 70°C higher than the melting point of the thermoplastic fibers that make up the unevenly porous nonwoven fabric 102 and the flat porous nonwoven fabric 104, and more preferably 5°C to 50°C higher. 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 better fusing the unevenly porous nonwoven fabric 102 and the flat porous nonwoven fabric 104. Moreover, 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 collapse due to the hot air.

[0077] In the above manufacturing method, the push-in member 130 is not limited to one having push-in portions 131 continuous in the first direction D1 as shown in Fig. 8. For example, the push-in portions 131 may be formed in a lattice shape, with square-shaped recesses 132 between the lattice-shaped push-in portions 131. In this case, the height of the saddle portion 15 to be formed becomes higher, and the unevenness becomes more distinct.

[0078] In the manufacturing method of the nonwoven fabric of this embodiment, it is preferable to have a cooling step after blowing the first hot air W1. For example, as shown in FIG. 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 porous nonwoven fabric 102 obtained by blowing the first hot air W1 is aligned along the outer periphery of the drum of the support 120. This makes it possible to keep the support 120 at a certain temperature or lower, and to peel off the obtained nonwoven fabric while maintaining its shape. As a result, the shape of the walls 11B and 15B of the first fiber layer M1 is well maintained in the manufactured nonwoven fabric 20, and good cushioning properties, liquid absorbency, and the resulting dryness of the surface can be improved.

[0079] The thermoplastic fibers constituting the nonwoven fabric of the present invention can be any fibers commonly used as materials 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. Composite fibers may have, for example, a core-sheath structure or a side-by-side structure. When using composite fibers containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air blown onto the fiber web in the manufacturing process is preferably equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component. More preferably, the temperature is equal to or higher than the melting point of the low melting point component and 10°C lower than the melting point of the high melting point component, and even more preferably, the temperature is 5°C or higher than the melting point of the low melting point component and 20°C or lower than the melting point of the high melting point component. In terms of elasticity, the more the core of the core-sheath structure composite fibers have, the higher the elasticity. Therefore, it is preferable that the core component is larger in terms of cross-sectional area ratio. A specific example of a composite fiber having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component is a composite fiber having a core-sheath structure in which the sheath is a polyethylene resin (hereinafter also referred to as PE) and the core is a polyethylene terephthalate resin (hereinafter also referred to as PET). Furthermore, in composite fibers with a core-sheath structure, when the resin component of the sheath has a lower glass transition point than the resin component of the core (hereinafter referred to as a low-glass transition point resin component; for example, the resin component of the core is PET and the resin component of the sheath is PE), the thickness recovery of the nonwoven fabric can be further improved by reducing the mass ratio of the low-glass transition point resin component.

[0080] The nonwoven fabric of the present invention can be used in various applications. For example, it can be used as a component of various absorbent articles. The various absorbent articles broadly include articles used to absorb liquids discharged from the body, such as diapers for adults and infants, sanitary napkins, panty liners, and urine pads.

[0081] An absorbent article having the nonwoven fabric of the present invention typically comprises a top sheet, a back sheet, and a liquid-retentive absorbent interposed between the two sheets. In the absorbent article, the nonwoven fabric of the present invention can be suitably used as the top sheet that contacts the wearer's skin. EXAMPLES

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

[0083] Example 1 Based on the production method shown in FIG. 6, the nonwoven fabric shown in FIGS. 2 to 5 was produced under the following conditions, and this was used as a nonwoven fabric sample of Example 1. The first fiber web 100 is made of thermoplastic fibers having a fineness of 1.8 dtex (fiber diameter 16 μm) and a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) and a basis weight of 30 g / m 2 The second fiber web 103 was made of thermoplastic fibers having a fineness of 1.8 dtex (fiber diameter 16 μm) and a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) and a basis weight of 20 g / m 2 The fiber web was obtained as follows. In the support 120, the projections 121 including the spires 122 had an MD pitch of 5 mm and a CD pitch of 5 mm in plan view, and the projection height including the spires 122 was 3.5 mm. The planar shape of the projections 121 from the spire 122 side was a diamond. The CD pitch of the pushing portion 131 of the pushing member 130 was 5 mm, and the pushing portion height was 5 mm. The temperature of the first hot air W1 was 160°C, and the wind speed was 10 m / sec. In this way, an unevenly open nonwoven fabric 102 (first fiber layer M1) having first open holes 31 with the hole area and planar shape shown in Table 1 was produced. The temperature of the second hot air against the second fiber web 103 was 160°C, and the air speed was 5 m / sec. The apertures in the flat apertured nonwoven fabric 104 were formed by punching with a punching blade. In this way, a flat apertured nonwoven fabric 104 (second fiber layer M2) having the aperture area and planar shape of the second aperture portions 32 shown in Table 1 was produced. The temperature of the third hot air W3 blown onto the laminate of the unevenly apertured nonwoven fabric 102 and the flat apertured nonwoven fabric 104 was 139°C and the air speed was 1 m / sec. In this way, a nonwoven fabric sample of Example 1 having the shape shown in Figs. 2 to 5 was produced.

[0084] The nonwoven fabric sample of Example 1 produced included a plurality of recessed portions 4 in which the first openings 31 and the second fiber layer M2 were laminated in the thickness direction, and a plurality of vertical through-holes 5 in which the first openings 31 and the second openings 32 penetrated in the thickness direction. The vertical through-holes 5 were located in an area sandwiched between the recessed portions 4 in the planar direction of the nonwoven fabric sample, and the second openings 32 constituting the vertical through-holes 5 were present across the first openings 31 and the protruding portions 1 of the first fiber layer M1. The number of vertical through-holes 5 per unit area was smaller than that of the recessed portions 4. The second openings 32 had a larger hole area and opening pitch than the first openings 31, as shown in Table 1. In addition, the nonwoven fabric sample of Example 1 had a compressive strength of 4.9 mN / cm 2 (0.05gf / cm 2 ) The thickness under load was 6 mm.

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

[0086] Example 3 A nonwoven fabric sample of Example 3 was prepared in the same manner as in Example 1, except that the hole area and planar shape of the second open holes 32 were as shown in Table 1.

[0087] Example 4 A nonwoven fabric sample of Example 4 was produced in the same manner as in Example 1, except that the opening pitch of the second open holes 32 was set as shown in Table 1.

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

[0089] Comparative Example 2 A nonwoven fabric sample of 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 carried out using the nonwoven fabric samples of each of the Examples and Comparative Examples. (1) Test using horse blood (1-1) Horse blood Defibrinated horse blood manufactured by Japan Biomaterials Center Co., Ltd. was adjusted to 24 cP and used. (1-2) Absorption time test using horse blood For each nonwoven fabric sample, 30 g / cm2 was applied from the top of one side. 2 The load was evenly applied to the 850 mm cross-sectional area test piece placed approximately in the center of each nonwoven fabric sample. 2 A tube was placed in the hole and fake urine was injected through it. 3g was injected twice, three minutes apart, and the time (seconds) until the entire amount was absorbed was measured. When horse blood was no longer visible inside the tube, it was deemed that the entire amount had been absorbed. The above procedure was carried out three times, and the average of the two times was taken as the liquid absorption time (seconds). The shorter the liquid absorption time, the easier it was for the liquid to penetrate into the inside, i.e., it indicates excellent liquid absorption properties. (1-3) Liquid spreading test using horse blood After measuring the absorption time, the area of ​​the horse blood spread on each nonwoven fabric sample was measured and recorded as the horse blood spread area. (2) Test using artificial urine (2-1) Artificial Urine Composition: 1.940% by mass urea, 0.795% by mass sodium chloride, 0.110% by mass magnesium sulfate, 0.062% by mass calcium chloride, 0.197% by mass potassium sulfate, 0.010% by mass Red No. 2 (dye), water (96.886% by mass), adjusted to 1.2 cp. (2-2) Absorption time test using simulated urine For each nonwoven fabric sample, 20 g / cm2 was applied from the top of one side. 2 The load was evenly applied to a test piece with a cross-sectional area of ​​1000 mm2 placed approximately in the center of each nonwoven fabric sample. 2A cylinder was placed over the container and the artificial urine was poured in through it. 40g was poured in three times every 10 minutes, and the time (seconds) until the entire amount was absorbed was measured. When artificial urine could no longer be seen inside the cylinder, it was deemed that the entire amount was absorbed. The above procedure was carried out three times, and the average of the three times was taken as the liquid absorption time (seconds). The shorter the liquid absorption time, the easier it is for the liquid to penetrate into the interior, i.e., it indicates excellent liquid absorption properties. (2-3) Liquid spreading test using simulated urine After measuring the absorption time, the area of ​​the artificial urine spread on each nonwoven fabric sample was measured and defined as the artificial urine spread area.

[0091] [Table 1]

[0092] As shown in Table 1, the nonwoven fabric samples of each Example had a shorter absorption time and suppressed liquid spreading for both liquids of horse blood and artificial urine viscosity compared to the nonwoven fabric samples of each Comparative Example. In other words, the nonwoven fabric samples of each Example realized high liquid permeability for excreted liquids with different properties, 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, each fiber layer including a fiber fusion part at the intersection of fibers, The first fiber layer has a concavo-convex structure including a plurality of convex parts and a plurality of bottom parts provided between adjacent convex parts. Each of the plurality of convex parts includes a top part and a wall part supporting the top part. Each of the plurality of bottom parts is provided with a first opening part penetrating in the thickness direction, The second fiber layer is provided on the side where the bottom part of the first fiber layer is located, A plurality of second opening parts penetrating in the thickness direction are intermittently arranged in the plane direction of the nonwoven fabric in the second fiber layer, The nonwoven fabric includes a plurality of concave parts in which the second fiber layer is laminated in the thickness direction with respect to the first opening part, and a plurality of upper and lower through-hole parts in which the first opening part and the second opening part penetrate in the thickness direction, respectively. The upper and lower through-hole parts are in a region sandwiched by the concave parts in the plane direction of the nonwoven fabric, and the second opening parts constituting the upper and lower through-hole parts exist across the first opening part and the convex parts of the first fiber layer. A nonwoven fabric for absorbent articles.

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 part has a larger hole area and / or opening pitch than the first opening part.

5. The nonwoven fabric for absorbent articles according to claim 1, wherein a hollow part is arranged between the second fiber layer inside the convex part of the first fiber layer.

6. The basis weight is 20 g / m ２ or more and 150 g / m ２ or less. The nonwoven fabric for absorbent articles according to claim 1.

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 vertically oriented.

9. An absorbent article having the nonwoven fabric for absorbent articles according to any one of claims 1 to 8.

10. A pressing step of placing a first fiber web on a support having a concavo-convex shape including a plurality of protrusions and recesses between the protrusions, pressing the first fiber web along the recesses by a pressing portion of a pressing member to shape it, and opening holes at locations corresponding to the protrusions to form a concavo-convex perforated fiber web having a perforated surface on the side opposite to the support; After removing the pressing member from the support, a step of blowing a first hot air onto the concavo-convex perforated fiber web to fuse the fibers together to obtain a concavo-convex perforated nonwoven fabric; A step of blowing a second hot air onto a second fiber web to fuse the fibers together and forming perforations penetrating in the thickness direction at intervals in the plane direction to obtain a flat perforated nonwoven fabric; A step of laminating the flat perforated nonwoven fabric on the perforated surface side of the concavo-convex perforated nonwoven fabric; A heat fusion step of blowing a third hot air to fuse the fibers of the concavo-convex perforated nonwoven fabric and the flat perforated nonwoven fabric together, the method for manufacturing a nonwoven fabric for absorbent articles having these steps.

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