Nonwoven fabric for absorbent articles

Abstract

Provided is a nonwoven fabric for absorbent articles which has good cushioning properties, excellent body pressure dispersion properties, and excellent liquid flow prevention properties. [Solution] A nonwoven fabric 10 for absorbent articles has a first fiber layer M1 and a second fiber layer M2 laminated in the thickness direction and includes fiber fusion parts at the intersections of the fibers, in which the first fiber layer has an uneven structure with a plurality of protruding parts 1 and a bottom part 2 provided between adjacent protruding parts, and each of the plurality of protruding parts has an apex 1A and a wall part 1B supporting the apex, and the bottom part has an opening part 3 penetrating through in the thickness direction, and a second fiber layer is provided on the side where the bottom part of the first fiber layer is located, and the second fiber layer has, on the side facing the first fiber layer, raised parts 5 that extend from the opening parts of the first fiber layer into areas partitioned by the wall parts, and the basis weight of the nonwoven fabric for absorbent articles is 40 g / m 2 More than 120g / m 2 The following is the result.

Description

[Technical field]

[0001] The present invention relates to nonwoven fabrics 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 come in a variety of structures. For example, Patent Document 1 describes a nonwoven fabric having a concave-convex structure with a plurality of ridges and a bottom with holes at the bottom as a top sheet of an absorbent article. Patent Document 2 describes a nonwoven fabric having a first nonwoven fabric layer and a second nonwoven fabric layer laminated together. The first nonwoven fabric layer has a concave-convex structure, and the second nonwoven fabric layer has a substantially flat shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-467 A [Patent Document 2] JP 2019-44293 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a nonwoven fabric having openings at the bottom of its uneven structure is used as a topsheet of an absorbent article, the unevenness provides cushioning, and the presence of the openings can enhance the liquid absorbency of the absorbent article. On the other hand, the excreted liquid absorbed by the absorbent article has various viscosities, and the behavior of the absorbent article differs depending on the viscosity. For example, low-viscosity liquid such as urine has high mobility and tends to wet and spread in a planar direction. High-viscosity liquid such as loose stool and menstrual blood has relatively low mobility but tends to remain on the surface, so it wets and spreads to a certain extent. This wet spreading increases the chances of the liquid adhering to the skin. In response to this, in recent years, in absorbent articles, from the viewpoint of reducing the adhesion of the liquid to the skin and suppressing skin troubles, it is required to quickly draw in liquids of various viscosities to prevent the liquid flow such as the wet spreading. Regarding the liquid flow prevention property, it is possible to increase the area of ​​the openings in the nonwoven fabric or increase the porosity (hereinafter, these are collectively referred to as the expanded arrangement of the openings). However, simply expanding the openings alone increases the voids in the nonwoven fabric, which is limited in terms of the cushioning properties and body pressure dispersion properties of the nonwoven fabric. In addition, if the openings are expanded too much, it is likely that liquid will return to the surface of the nonwoven fabric, which may actually increase the adhesion of liquid to the skin. In this way, the improvement in the liquid flow prevention property achieved by expanding the arrangement of the open holes is in a trade-off relationship with the cushioning properties, body pressure dispersion properties and liquid backflow prevention properties of the nonwoven fabric, and there is room for improvement.

[0005] In view of the above, the present invention relates to a nonwoven fabric for absorbent articles that has good cushioning properties, excellent body pressure dispersion properties, and excellent liquid flow prevention properties. [Means for solving the problem]

[0006] The present invention relates to a nonwoven fabric for absorbent articles, which has a first fiber layer and a second fiber layer laminated in the thickness direction and includes fiber fusion portions at the intersections between fibers, the first fiber layer has an uneven structure with a plurality of protruding portions and a bottom portion provided between adjacent protruding portions, each of the plurality of protruding portions has an apex and a wall portion supporting the apex, and the bottom portion has an opening portion penetrating through in the thickness direction, the second fiber layer is provided on the side of the first fiber layer on which the bottom portion is located, and the second fiber layer has a raised portion on the side facing the first fiber layer that extends from the opening portion of the first fiber layer into an area partitioned by the wall portion, and the basis weight of the nonwoven fabric for absorbent articles is 40 g / m 2 More than 120g / m 2 The nonwoven fabric for absorbent articles has a strength of 4.9 mN / cm or less. 2 The thickness under load is 5 mm or more and 15 mm or less, and the opening area of ​​the opening is 20 mm 2 More than 35mm 2 The present invention provides a nonwoven fabric for absorbent articles, wherein the opening rate of the openings in the nonwoven fabric for absorbent articles is 15% or more and 30% or less. Effect of the Invention

[0007] The nonwoven fabric for absorbent articles of the present invention has good cushioning properties, excellent body pressure dispersion properties, and excellent liquid flow prevention properties. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a schematic diagram of a preferred embodiment of a nonwoven fabric for absorbent articles according to the present invention. [Diagram 2] 1 is a plan view showing an example of an arrangement of apertures in a nonwoven fabric for absorbent articles according to the present invention, and showing a measurement area for the aperture ratio in the example. [Diagram 3] 1 is a plan view showing a specific example of a nonwoven fabric for absorbent articles according to the present embodiment, viewed from one side. [Figure 4] 4 is a cross-sectional view taken along the line R1-R1 of the nonwoven fabric for absorbent articles shown in FIG. 3. [Diagram 5] 4 is a cross-sectional view taken along the line R2-R2 of the nonwoven fabric for absorbent articles shown in FIG. 3. [Figure 6] 4 is a cross-sectional view taken along the line R3-R3 of the nonwoven fabric for absorbent articles shown in FIG. 3. FIG. [Figure 7] 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 porous nonwoven fabric by a first hot air, (C) shows a process for laminating a second fibrous web onto the porous nonwoven fabric, and (D) shows a process for integrating the porous nonwoven fabric and the second fibrous web by a second hot air, thereby forming the second fibrous web into a nonwoven fabric. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. 13 is a plan view showing a state in which the support body and the push-in member are combined. [Figure 11] 1(A) to 1(C) are photographs of the nonwoven fabric sample of Example 1. [Figure 12] 12 is a drawing-substitute photograph showing an enlarged cross section in the thickness direction of the nonwoven fabric sample of FIG. 11(C). [Figure 13] 1 is a drawing-substitute photograph showing a nonwoven fabric sample of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A preferred embodiment of the nonwoven fabric for absorbent articles according to the present invention will be described below with reference to the drawings. In this specification, the nonwoven fabric for absorbent articles may be simply referred to as nonwoven fabric. The nonwoven fabric 10 of this embodiment is a 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 together by the fiber fusion parts at the intersections of the fibers of each other.

[0010] The nonwoven fabric 10 of this embodiment has a first fiber layer M1 and a second fiber layer M2 laminated in the thickness direction 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 closer to the skin than 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. The planar direction 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 corresponds to a direction Z perpendicular to the straight line L.

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

[0012] The outer shape of one surface side 10T of top 1A may be a flat surface or a curved surface. From the viewpoint of making it easier to recognize the depth of the unevenness and making the shadows around openings 3 in bottom 2, which will be described later, more clear, it is preferable that one surface side 10T of top 1A is a flat surface.

[0013] An end portion (also referred to as a root portion 1D) of the other surface side 10B of the wall portion 1B abuts against the second fiber layer M2. In a contact region 4 between the wall portion 1B and the second fiber layer M2, the root portion 1D of the wall portion 1B is embedded in and integrated (fixed) with the second fiber layer M2. From the viewpoints of increasing the bonding strength and maintaining the uneven shape of the first fiber layer M1, it is preferable that the root portion 1D of the wall portion 1B and the second fiber layer M2 are integrated by a fused fiber portion at an intersection between the constituent fibers of the root portion 1D of the wall portion 1B and the constituent fibers of the second fiber layer M2.

[0014] 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 having a cross section in the thickness direction 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 (the 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, and a pressure of 4.9 mN / cm is applied. 2 A load of 1000 MPa is applied to the cross section in the thickness direction Z. In this state, the cross section in the thickness direction Z is observed at 20 times by the microscope, and the fiber layer in the first fiber layer M1 that is in contact with the flat plate is designated as a top portion 1A. The portion connecting the end of the top portion 1A and the surface of one surface side 10T of the second fiber layer M2 is designated as a wall portion 1B. In specifying the boundary between top 1A and wall 1B, the thickness of top 1A in the portion where wall 1B does not exist is defined as the thickness of the end portion of top 1A, and the portion excluding this thickness is defined as wall 1B.

[0015] The bottom 2 of the first fiber layer M1 refers to a region including the bottom of a recess (inter-protrusion recess 2U) recessed between the protrusions 1, 1 on the other surface 10B and an end (root 1D) of the wall 1B on the other surface 10B. This bottom 2 has an opening 3 penetrating in the thickness direction Z. In the example shown in FIG. 1, the entire bottom 2 except for the root 1D is the opening 3, and in this case, the root 1D of the wall 1B is the bottom 2. The penetration in the opening 3 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.

[0016] The openings 3 are holes formed by processing the first fiber layer M1, and have a hole area that is much 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 openings 3, but the size of the openings 3 can be appropriately selected depending on the width of the bottom 2, etc. For example, in the first fiber layer M1, the entire bottom 2 except for the base 1D may not be the openings 3, and a fiber layer extending from the base 1D may be present around the openings 3. The openings 3 are at least 20 mm 2 It is preferable that the opening area is equal to or more than this. The size of the opening 3 can be measured using the above-mentioned microscope. Specifically, the area of ​​the opening 3 is measured at 10 points using the microscope, and the average value of these is regarded as the opening area of ​​each opening.

[0017] The planar shape of the openings 3 may be various from the viewpoint of enhancing liquid permeability, and examples thereof include a circle, an ellipse, and a rectangle.

[0018] The second fiber layer M2 is disposed on the side where the bottom of the first fiber layer M1 is located, and has a raised portion 5 on the surface facing the first fiber layer M1, which extends from the opening 3 of the first fiber layer M1 into the region defined by the wall portion 1B. That is, the raised portion 5 is located on one surface side 10T of the base portion 1D of the wall portion 1B in the contact region 4, and is in the space between the protrusions 1, 1 of the first fiber layer M1 and sandwiched by the wall portion 1B. On the other hand, the second fiber layer M2 in the contact region 4 adjacent to the raised portion 5 forms a recessed portion 6 due to being bitten into by the wall portion 1B.

[0019] Since the protrusions 5 of the second fiber layer M2 extend from the openings 3 toward the first fiber layer M1, the liquid received on the one side 10T of the first fiber layer M1 is drawn in more quickly, improving the absorption speed. More specifically, the protrusions 5 are located in recesses (inter-protrusion recesses 2U) recessed on the other side 10B between the protrusions 1, 1 of the first fiber layer M1. The recesses physically block the flow of the liquid in the planar direction, regardless of the viscosity of the liquid, so that more liquid can be dropped into the recesses. The protrusions 5 located there reliably capture the liquid, and the protrusions 5 cooperate with the openings 3 to quickly draw the liquid from the first fiber layer M1 to the second fiber layer M2. In this way, the liquid flow (wet spread) prevention on the surface of the one side 10T of the nonwoven fabric 10 (first fiber layer M1) is improved. Furthermore, the amount and area of ​​remaining liquid on the surface of one side 10T of nonwoven fabric 10 are also reduced, resulting in less adhesion of the liquid to the skin and preventing skin troubles. In order to make the above-mentioned action more effective, it is preferable that the surface of the protuberance 5 has fuzz that extends further to the one surface side 10T. Furthermore, the presence of the raised portions 5 prevents the wall portions 1B from collapsing sideways due to external pressure, thereby making it possible to provide the nonwoven fabric 10 with both superior cushioning properties and liquid permeability.

[0020] The fact that the first fiber layer M1 (i.e., the base portion 1D of the wall portion 1B) and the second fiber layer M2 are integrated by fusion of their fibers significantly contributes to the rapid absorption of liquid from the first fiber layer M1 to the second fiber layer M2 through the aforementioned openings 3 and protrusions 5. That is, the fibers in the first fiber layer M1 and the second fiber layer M2 are integrated while maintaining their fibrous state and intertwining, and therefore, unlike those bonded with an adhesive such as a hot melt type adhesive, a three-dimensional mesh structure of the fibers at the interface between the two layers is maintained, allowing liquid to be absorbed without delay through the spaces in the mesh.

[0021] Furthermore, the nonwoven fabric 10 has the following fiber configuration: (1) The basis weight of the nonwoven fabric 10 is 40 g / m 2 More than 120g / m 2 The following is the result. (2) Nonwoven fabric 10: 4.9 mN / cm 2 The thickness under load is 5 mm or more and 15 mm or less. (3) The opening area of ​​the opening 3 is 20 mm 2 More than 35mm 2 The following is the result. (4) The aperture ratio of the apertures 3 in the nonwoven fabric 10 is 15% or more and 30% or less.

[0022] The above (3) suppresses liquid backflow (liquid backflow from the other surface side 10B to the one surface side 10T of the nonwoven fabric 10) while increasing the open area of ​​each opening 3. This increases the area in the planar direction of each entering protrusion 5 (area when viewed from the one surface side 10T). The above (4) suppresses the liquid return while increasing the arrangement frequency of the apertures 3 in a plan view from one surface side 10T of the nonwoven fabric 10. This increases the arrangement frequency of the protruding protrusions 5. The above (3) and (4) increase the open area and open area ratio within the range that suppresses liquid backflow in the nonwoven fabric 10, thereby improving the rapid liquid absorption and liquid flow prevention properties of the nonwoven fabric 10. In particular, the rapid liquid absorption and liquid flow prevention properties are significantly improved for highly viscous liquids, such as loose stools and menstrual blood.

[0023] The configurations relating to the openings 3 in (3) and (4) can be well formed under the conditions of (1) and (2) above, and can be stably maintained. That is, the basis weight in (1) above allows the individual openings 3 to be well formed even if they are large, and tearing or the like is unlikely to occur. The thickness in (2) above expands the allowable range of the openings 3 that can be formed while taking into consideration the prevention of liquid return, making the openings 3 in (3) and (4) above possible.

[0024] The nonwoven fabric 10 has the above-mentioned fiber structure and the above-mentioned uneven structure under the fiber structure, thereby providing a soft, thick structure. This gives the nonwoven fabric 10 good cushioning properties and excellent body pressure dispersion. As a result, the body pressure of the body that touches the nonwoven fabric 10 is dispersed without being concentrated in one place, and the body feels soft and as if it is being gently wrapped by the deformation of the nonwoven fabric 10. Furthermore, when the nonwoven fabric 10 is used as a member closer to the skin than the absorbent body in an absorbent article, such as a top sheet, the cushioning and body pressure dispersion properties described above are more effective. That is, when the absorbent article receives drainage and the absorbent body absorbs the liquid, the absorbent body becomes hard. For example, the pulp fibers become hard by absorbing liquid and clumping together. However, by arranging the nonwoven fabric 10 as a member closer to the skin than the absorbent body, the hardness of the absorbent body after absorbing liquid is less likely to be transmitted to the wearer's body (buttocks, etc.) due to the cushioning and body pressure dispersion properties described above, and the comfortable feel is easily maintained even after urination.

[0025] As described above, the nonwoven fabric 10 has good cushioning properties, excellent body pressure dispersion properties, and excellent liquid flow prevention properties.

[0026] The basis weight of the nonwoven fabric 10 is set to 45 g / m from the viewpoint of making the above-mentioned effect more effective and improving the texture of the nonwoven fabric. 2 More than 50 g / m is preferable. 2 More preferably, 55 g / m 2 More preferably, 60 g / m 2 More preferably, 80 g / m 2 The above is even more preferable. In addition, the basis weight of the nonwoven fabric 10 is preferably 150 g / m2 so as not to impede the comfortable feel of the wearer.2 Less than 130 g / m 2 Less than 120 g / m is more preferable. 2 The following is even more preferred:

[0027] Nonwoven fabric 10: 4.9mN / cm 2 (0.05gf / cm 2 ) The thickness under load is preferably 6 mm or more, more preferably 7 mm or more, even more preferably 8 mm or more, and even more preferably 9 mm or more, from the viewpoint of making the above-mentioned action more effective. 2 The thickness under load is preferably 14 mm or less, more preferably 13 mm or less, and even more preferably 12 mm or less, from the viewpoint of not impeding the comfortable feel of the wearer. The above 4.9mN / cm 2 The load is the load that simulates fluffing on the surface of the nonwoven fabric. The thickness is 4.9 mN / cm 2 The measurement can be performed under load using a laser displacement meter or the like.

[0028] In order to make the above-mentioned action more effective, the opening area of ​​the opening 3 is set to 21 mm 2 More than 23mm is preferable. 2 More preferably, 25 mm or more 2 The above is more preferable. From the viewpoint of suppressing liquid return, the opening area of ​​the opening 3 is 33 mm 2 Less than 31mm is preferred 2 Less than 29mm is more preferable 2 The following is even more preferred:

[0029] From the viewpoint of making the above-mentioned action more effective, the aperture ratio of the openings 3 is preferably 18% or more, and more preferably 20% or more. From the viewpoint of suppressing liquid return, the aperture ratio of the openings 3 is preferably 28% or less, more preferably 26% or less, and even more preferably 24% or less.

[0030] The aperture ratio of the apertures 3 can be measured using a microscope, similar to the aperture area described above. One surface 10T of the nonwoven fabric 10 is viewed in plan view using a microscope, and the arrangement of the apertures 3 confirmed is identified by specifying two directions constituting the arrangement, for example, the longitudinal direction of the nonwoven fabric 10 and the width direction perpendicular thereto. In the arrangement, the center points of the apertures 3, 3 adjacent to each other in one direction (for example, the longitudinal direction) are connected in the one direction, and the center points of the apertures 3, 3 adjacent to each other in the other direction (for example, the width direction) are connected in the other direction to specify the arrangement region of the apertures 5. The ratio of the aperture area of ​​the apertures 5 to the region is calculated. This calculation is performed at 10 points, and the average is taken as the aperture ratio (rounded off to the nearest whole number).

[0031] For example, in the example shown in FIG. 2 The vertically elongated apertures 3 (=9m×3m) are arranged at equal intervals in the longitudinal direction Y and the width direction X. The arrangement J1 along the longitudinal direction Y and the adjacent arrangement J2 along the longitudinal direction Y are shifted in the longitudinal direction Y so that the arrangement positions of the apertures 3 do not coincide. Therefore, the aperture 3A in the arrangement J1 is adjacent in the width direction X to the aperture 3C in the arrangement J3. That is, in the example shown in FIG. 2, the distance between the center points of the aperture 3A in the arrangement J1 and the aperture 3C in the arrangement J3 is the pitch in the width direction X of this arrangement, and the pitch is 15 mm. The distance between the center points of the apertures 3A and 3B adjacent in the longitudinal direction Y of the arrangement J1 is the pitch in the longitudinal direction Y of this arrangement, and the pitch is 16.1 mm. In FIG. 2, a line segment L1 is drawn connecting the center points of adjacent apertures 3A and 3B in the longitudinal direction Y in array J1. Similarly, a line segment L2 is drawn connecting the center points of adjacent apertures 3C and 3D in array J3 in the longitudinal direction Y. Next, a line segment L3 is drawn connecting the center points of apertures 3A in array J1 and aperture 3C in array J3. Similarly, a line segment L4 is drawn connecting the center points of apertures 3B in array J1 and aperture 3D in array J3. The area surrounded by lines L1 to L4 is the measurement area. This measurement area is 241.5 mm 2(=15 mm×16.1 mm) The measurement region includes central aperture 3E and one-quarter of each of apertures 3A to 3D. From this, the aperture ratio is calculated as 22% using the following formula. Open area rate (%) ={opening area (9mm×3mm)×2 / (15×16.1)}×100

[0032] The raised portion 5 is visible from the first fiber layer M1 side because it enters the first fiber layer M1 at the position of the opening 3 penetrating the first fiber layer M1 in the thickness direction Z. Therefore, when the nonwoven fabric 10 is viewed from the first fiber layer M1 side (one surface side 10T), the convex portion 1 of the first fiber layer M1 and the raised portion 5 of the second fiber layer M2 are visually recognized as being adjacent to each other. At this time, the shadow around the opening 3 at the bottom 2 of the first fiber layer M1 is emphasized by the presence of a valley formed by the base portion 1D of the wall portion 1B constituting the convex portion 1 and the bottom portion 7 of the raised portion 5 extending to the base portion 1D. When the fibers of the wall portion 1B are longitudinally oriented, the raised portion 5 is made of a fiber layer having a fiber orientation different from that of the wall portion 1B, and a dividing line is formed in which the degree of fiber orientation changes discontinuously between the two portions, which further emphasizes this shadow. Because the protrusions 5 are visible from the side of the first fiber layer M1, consumers of an absorbent article having the nonwoven fabric 10 as a topsheet can visually see that the nonwoven fabric has clear openings. As a result, consumers can be assured that the absorbent article has excellent liquid absorbency and can use the article with peace of mind. 1, the entire bottom 2 except for the base 1D is the opening 3, and the bottom 7 of the protuberance 5 is directly connected to the base 1D of the wall 1B. However, this is not limiting, and a fiber layer may be present around the opening 3 in the inter-protrusion recess 2U of the first fiber layer M1. In this case, the bottom 7 of the protuberance 5 of the second fiber layer M2 extends to the base 1D of the wall 1B via the fiber layer around the opening 3 in the inter-protrusion recess 2U, forming the valley and the dividing line.

[0033] From the viewpoint of enhancing the effect of highlighting the shadow between the root portion 1D of the wall portion 1B and the protuberance 5, it is preferable that the surface side of the second fiber layer M2 facing the first fiber layer M1 is a continuous fiber layer extending in the planar direction. In this way, the surface side of the second fiber layer M2 facing the first fiber layer M1 is a continuous fiber layer extending in the planar direction, so that the above-mentioned shadow portion becomes more noticeable as a different portion in the continuous fiber layer. In addition, when the fibers of the wall portion 1B of the first fiber layer M1 are oriented vertically, a dividing line where the fiber orientation changes discontinuously between the first fiber layer M1 and the second fiber layer M2 is formed, and the shadow is enhanced.

[0034] From a similar viewpoint, it is preferable that the bottom 7 extending downward from the raised portion of the protuberance 5 is connected to the contact region 4 between the wall portion 1B of the first fiber layer M1 and the second fiber layer M2. By connecting the bottom 7 to the contact region 4 in this manner, a valley is formed by the base portion 1D of the wall portion 1B and the bottom 7, and the shadow around the opening 3 at the bottom 2 of the first fiber layer M1 is further emphasized.

[0035] From the viewpoint of making the above-mentioned emphasis on shadows more clear, it is preferred that in the contact region 4 of the first fiber layer M1 between the wall portion 1B and the second fiber layer M2, the fibers of the second fiber layer M2 are oriented in the planar direction, and the fibers on the surface of the skirt portion 7 of the protuberance 5 have a fiber orientation different from that of the fibers of the wall portion 1B. By having the fibers on the surface of the skirt portion 7 have a fiber orientation different from that of the fibers of the wall portion 1B in this way, a dividing line is formed where the fiber orientation on the surface of the skirt portion 7 and the fiber orientation of the wall portion 1B change discontinuously, thereby emphasizing the shadows. The fibers on the surface of the base 7 of the raised portion 5 refer to the fibers in the portion that starts to rise from the base 1D of the wall portion 1B in the contact region 4. For example, the fibers on the surface of the raised portion 5 in a range of 2 mm in the planar direction from the base 1D toward the base 7. Specifically, the fiber orientation on the surface of the bottom 7 is a longitudinal orientation rate of less than 45%. A longitudinal orientation rate of less than 45% means that the fibers are oriented in a planar direction, and the longitudinal orientation rate is different from that of the fibers in the wall 1B, making the above-mentioned shadow clearer. Here, the fibers on the surface of the bottom 7 having a fiber orientation different from that of the fibers in the wall 1B means that the difference in longitudinal orientation rate between the two is 15% or more. From the viewpoint of further enhancing the above-mentioned effect, a ratio of 20% or more is preferable, and 30% or more is more preferable.

[0036] (Method of measuring the longitudinal orientation rate of fibers on the surface of the hem portion 7) As shown in FIG. 1, measurements are performed on the bottom hem 7 in the following procedure. That is, a cross section of the fiber layer including the protrusions 1 of the first fiber layer M1 and the bottom 7 defined in the cross section of the nonwoven fabric 10 in the thickness direction, including the second fiber layer M2, is observed with a scanning electron microscope (SEM) at a magnification of 35 to 100 times. A square line with a side of 500 μm is drawn on the observed image as a reference line. At this time, the line is drawn so that the fibers of the bottom 7 are included in the entire area of ​​the square. Each side (reference line) of the square is defined as a side perpendicular to the thickness direction and the planar direction of the cross section of the nonwoven fabric 10. The total number of fibers passing through the reference lines 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 follows: (number of longitudinal fibers) / (number of transverse fibers+number of longitudinal fibers)×100=longitudinal orientation rate (%). Ten measurements are taken, and the average is used as the longitudinal orientation rate value.

[0037] The ratio (H2 / H1) of the thickness H2 of the raised portion 5 to the thickness H1 of the first fiber layer M1 is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.15 or more, from the viewpoint of further enhancing the rapid liquid absorption and liquid flow prevention properties, and from the viewpoint of further enhancing the shadows. From the viewpoint of maintaining liquid permeability through the openings 3, the ratio (H2 / H1) of the thickness H2 of the protrusions 5 to the thickness H1 of the first fiber layer M1 is preferably 0.9 or less, more preferably 0.8 or less, and even more preferably 0.7 or less. The thickness H1 of the first fiber layer M1 refers to the height from the surface of one side 10T of the top portion 1A to the boundary with the second fiber layer M2 at the base portion 1D of the wall portion 1B in the contact region 4. 2 With this load applied, the process can be carried out in the same manner as in the above-mentioned method for dividing the fiber layer of the wall portion 1B.

[0038] The fiber diameter of the fibers in the second fiber layer M2 is preferably smaller than that of the fibers in the first fiber layer M1 when priority is given to the ability to absorb highly viscous body fluids or loose stools, and is preferably larger than that of the fibers in the first fiber layer M1 when priority is given to the ability to absorb urine. In either case, by having a certain degree of difference between the fiber diameters of the fibers in the first fiber layer M1 and the fibers in the second fiber layer M2, the protrusions 5 are exposed from the openings 3 in the first fiber layer M1, and the ability to quickly absorb liquid from the openings 3 can be improved. From this viewpoint, the absolute value of the difference between the fiber diameter (D1) of the fibers in the first fiber layer M1 and the fiber diameter (D2) of the fibers in the second fiber layer M2 (|D1-D2|) is preferably 1 μm or more, more preferably 1.5 μm or more, and even more preferably 2 μm or more. From the viewpoint of improving the clarity of the openings and the liquid drawing ability, the difference (|D1-D2|) is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, even more preferably 15 μm or less, even more preferably 10 μm or less, and even more preferably 7 μm or less.

[0039] When the ability to absorb highly viscous body fluids or loose stools is important, the fiber diameter of the fibers in the second fiber layer M2 is preferably smaller than that of the fibers in the first fiber layer M1. From the above viewpoints, the fiber diameter (D2) of the fibers in the second fiber layer M2 is preferably 8 μm or more, more preferably 10 μm or more, even more preferably 12 μm or more, and preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 16 μm or less. The fineness (D1) of the fibers in the first fiber layer M1 is preferably 12 μm or more, more preferably 14 μm or more, even more preferably 16 μm or more, and preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. When urine absorption is important, the fiber diameter of the fibers in the second fiber layer M2 is preferably larger than that of the fibers in the first fiber layer M1. From the above viewpoints, the fiber diameter (D2) of the fibers in the second fiber layer M2 is preferably 12 μm or more, more preferably 14 μm or more, even more preferably 16 μm or more, and preferably 40 μm or less, more preferably 35 μm or less, and even more preferably 30 μm or less. The fineness (D1) of the fibers in the first fiber layer M1 is preferably 8 μm or more, more preferably 10 μm or more, even more preferably 12 μm or more, and preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 16 μm or less. The above fiber diameter means the average fiber diameter in each fiber layer.

[0040] (Method of measuring average fiber diameter in each fiber layer) 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 magnified and observed using a scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.) and adjusted to a magnification (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 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 not perfectly circular, the line segment that connects two points on the periphery in the cross section and has the maximum diameter in the cross section is defined as the long axis, and the line segment that is perpendicular to the long axis and has the maximum length is defined as the short axis. The lengths of the long and short axes of each fiber are then measured by analyzing and calculating them using image analysis software or the like, and the arithmetic mean value of the long axis length and the short axis length of a single fiber is defined as the fiber diameter of each fiber, and the arithmetic mean value of the fiber diameters of 30 fibers is defined as the average fiber diameter of the fibers in this 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.

[0041] It is preferable that the nonwoven fabric 10 contains zinc oxide. This can impart antibacterial properties to the nonwoven fabric 10, and keep the body that comes into contact with it clean. In this regard, zinc oxide is generally known to have the effect of making fibers water-repellent. However, as described above, the nonwoven fabric 10 has a unique uneven structure that provides structural properties such as rapid liquid absorption and liquid flow prevention, so even if zinc oxide makes the fibers water-repellent, the effect is small, and it is possible for the nonwoven fabric 10 to coexist with zinc oxide. From the viewpoint of making the antibacterial action more effective, zinc oxide is preferably present in at least the first fiber layer M1, and is preferably present in both the first fiber layer M1 and the second fiber layer M2. Moreover, from the viewpoint of maintaining the antibacterial action for a longer period, zinc oxide is preferably contained in the fiber and used as a zinc oxide-containing fiber.

[0042] Next, a more preferred embodiment of the uneven structure described above in the nonwoven fabric 10 of this embodiment will be described.

[0043] The fibers of the wall 1B of the first fiber layer M1 are preferably oriented vertically with respect to the plane of the other surface 10B of the nonwoven fabric 10 (the second fiber layer M2). This vertical orientation of the fibers increases the support force of the wall 1B in the thickness direction with respect to the top 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 in combination with the elasticity due to the fiber structure of the fiber layer, it further enhances the cushioning and body pressure dispersion. That is, the soft feel of the nonwoven fabric 10 becomes even better. 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 effects of rapid liquid absorption and liquid flow prevention are more likely to be maintained even under load, and liquid return (wetback) from the absorbent body to the skin side is suppressed. The three-dimensional shape of the wall portion 1B acting in this way can be well maintained by being integrated with the second fiber layer M2 with high strength by the above-mentioned fused fiber portion. Moreover, since this integration utilizes the bonded state at the intersections of the fibers by the fused fiber portion, there is no need to collapse the lower portion of the wall portion 1B to ensure a bonding surface as in the case of bonding with a conventional hot melt adhesive. This allows the wall portion 1B to maintain a sufficient height.

[0044] The longitudinal orientation of the fibers in the wall portion 1B means that many of the 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 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.

[0045] (Method of measuring longitudinal orientation rate of fibers in wall portion 1B) As shown in FIG. 1, the wall portion 1B is measured in the following procedure. That is, the fiber layer cross section of the wall portion 1B defined in the cross section in the thickness direction of the nonwoven fabric 10, including the convex portion 1 of the first fiber layer M1 and the second fiber layer M2, is observed at 35 times magnification with a scanning electron microscope (SEM). A square line with a side of 500 μm is added to the observed image as a reference line. Each side (reference line) of the square is defined as a side perpendicular to the thickness direction and the planar direction in the cross section of the nonwoven fabric 10. The total number of fibers passing through the reference line consisting of each side of the square is counted. The fibers passing through the square reference line perpendicular to the planar direction of the nonwoven fabric 10 are defined as the "number of horizontal fibers", and the fibers passing through the square reference line perpendicular to the thickness direction of the nonwoven fabric 10 are defined as the "number of vertical fibers". The longitudinal orientation rate is calculated as (number of vertical fibers) / (number of horizontal fibers+number of vertical fibers)×100=longitudinal orientation rate (%). 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 Figure 1. The thickness direction corresponds to a direction Z perpendicular to the straight line L.

[0046] The wall 1B of the first fiber layer M1 preferably has a shape extending perpendicular to the plane of the other surface 10B of the nonwoven fabric 10 (second fiber layer M2). The wall 1B having a perpendicular wall surface further enhances the above-mentioned liquid flow prevention property. In addition, the valley between the protuberance 5 at the base 1D of the wall 1B becomes narrower, and the shadow becomes stronger. Also, the shadow can be recognized as being raised from the vertical wall 1B. This further improves the visibility of the opening 3. Furthermore, the vertical wall 1B vertically connects the top 1A and the second fiber layer M2, further enhancing the above-mentioned shadow. It also strengthens the aforementioned effect of the longitudinal orientation of the fibers. That is, the soft fiber layer of the top 1A tends to remain supported by the elastic fiber layer of the wall 1B. The thickness of the fiber layer of the protrusion 1 is felt through this top 1A, and a softer touch is easily obtained. More specifically, this soft touch is felt as a gentle and reassuring thickness under light pressure that is just enough to touch, and is felt as a resilient and soft thickness that is unlikely to wear out even when the protrusion 1 deforms under further pressure. Such excellent cushioning properties further improve the feel of the skin due to the aforementioned uneven structure.

[0047] The "perpendicular" 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 of the nonwoven fabric 10. The angle θ means the intersection angle between the plane of the other side 10B of the nonwoven fabric 10 and the extension line of the wall 1B. Specifically, as shown in FIG. 1, in a cross section in the thickness direction including the convex portion 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). This angle θ can be obtained by observing a micrograph of the cross section obtained by the above-mentioned microscope.

[0048] 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 determined by taking the line connecting the boundary point between the top 1A and the wall 1B and the boundary point between 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 viewpoints of further emphasizing the above-mentioned shadows in the nonwoven fabric 10 and making the above-mentioned effect of the longitudinal orientation of the fibers more effective.

[0049] In addition, it is preferable that the first fiber layer M1 has hollow regions 1C on the other surface side 10B of the protrusions 1. The hollow regions 1C are spaces that are not substantially filled with the fibers of the nonwoven fabric 10. Specifically, the hollow regions 1C have a fiber density of 10 fibers / mm 2 or less, as determined by the method described below. 2 The lower the fiber density in the hollow region 1C, the better. Furthermore, it is preferable from the viewpoint of improving liquid permeability that the raised portions 5A of the second fiber layer M2 also penetrate into the hollow regions 1C of the first fiber layer M1.

[0050] (Method of measuring fiber density) The fiber density can be measured by observing the cross section of the nonwoven fabric 10 using the following method. The nonwoven fabric 10 is cut in the thickness direction so as to pass through the area to be measured (for example, between the wall portions 1B). 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 (100x to 500x) that allows the measurement of approximately 2 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 results of the measurements at five locations shall be averaged to determine the fiber density of the sample.

[0051] The hollow region 1C on the other surface side 10B of the projections 1 further improves the soft feel of the projections 1, further enhances the cushioning properties described above, and further improves the feel of the nonwoven fabric 10 against the skin. When the nonwoven fabric 10 is used as a top sheet of an absorbent article, the presence of the hollow region 1C cuts off the liquid return path from the absorbent body, further improving the prevention of liquid return. In addition, the hollow region 1C also serves as a primary storage space in the event of excessive excretion, and can reduce the amount of liquid remaining on the skin contact side of the top sheet.

[0052] Next, a specific example (nonwoven fabric 20) of the nonwoven fabric 10 shown in Fig. 1 will be described with reference to Fig. 3 to Fig. 6. The nonwoven fabric 20 has the configuration described above for the nonwoven fabric 10. 3 to 6, in plan view from one surface side 20T, the nonwoven fabric 20 has a plurality of ribs 11 extending in one direction Y as the protrusions 1 of the first fiber layer M1 and arranged at a distance from each other in a direction X intersecting the one direction Y. The other surface side 20B of the ribs 11 is formed as a hollow region 11C. 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 component 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.

[0053] 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.

[0054] Each of the ridges 11 includes a crest 11A and a wall 11B supporting the crest 11A. The crest 11A is a fiber layer that contacts the wearer's skin in an absorbent article, and the wall 11B is a fiber layer that connects the crest 11A and the second fiber layer M2 in the thickness direction. That is, when the nonwoven fabric 20 is applied to an absorbent article, the one surface side 20T becomes the skin contact surface side, and the other surface side 20B becomes the non-skin contact surface side. As described above, it is preferable that the fibers of the wall 11B are vertically oriented. In addition, it is preferable that the shape of the wall extends perpendicular to the second fiber layer M2, and vertically connects the crest 11A and the bottom 12 where the openings 3 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 rib portion 11 (a thickness direction cross section at the position of line R1-R1 along the width direction X in FIG. 3), as shown in FIG. 4. Furthermore, the "vertical" of wall 11B refers to the interior angle between center line M of the width of the fiber layer of wall 11B and straight line L tangent to the surface of the other side 20B of nonwoven fabric 20 (second fiber layer M2) in a cross section perpendicular to the extending direction of rib 11 (thickness direction cross section at line R1-R1 along direction X intersecting with direction Y in FIG. 3), as shown in Fig. 4. This angle θ can be determined by observing a micrograph of the cross section along line R1-R1 obtained with the above-mentioned microscope.

[0055] 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 preferably 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 15B can be measured in a cross section perpendicular to the extension direction of saddle portion 15 (thickness direction cross section at the position of line R2-R2 along one direction Y in FIG. 3) as shown in FIG. 5, in the same manner as the measurement method described above for wall portion 11B.

[0056] 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, even if there is body pressure from the wearer when wearing the absorbent article, the distance between the top portion 11A and the absorbent body side of the other surface side (non-skin contact surface side) 20B is easily maintained, making it even harder for liquid to return to the one surface side (skin contact surface side) 20T. Furthermore, the presence of the saddle portion 15 acts to block excreted liquid between the ridges 11, 11, enhancing the ability to prevent liquid from flowing on one surface side (skin contact surface) 20T of the nonwoven fabric 20.

[0057] In a plan view from one surface side 20T of the nonwoven fabric 20, the saddle portion 15 extends in a direction X intersecting with the direction Y in which the rib portion 11 extends. The direction X in which the saddle portion 15 extends can be various directions as long as it connects adjacent ribs 11, and is preferably a direction perpendicular to the direction Y in which the rib portion 11 extends. For example, it is preferable that the direction Y in which the rib portion 11 extends is the longitudinal direction of the absorbent article, and the direction X in which the saddle portion 15 extends and intersects with the direction Y is the width direction of the absorbent article. Hereinafter, the direction Y and the direction X perpendicular to the direction Y are also referred to as the extension direction Y of the rib portion 11 and the extension direction X of the saddle portion 15. In addition, the planar shape of each saddle portion 15 as viewed from one surface side 20T is not limited to a rectangle as shown in Fig. 3, and may be various shapes. For example, the planar shape of the saddle portion 15 as viewed from one surface side 20T may be such that the width increases toward the ridge portion 11.

[0058] The saddle portions 15 are arranged in a plurality of band regions 16 extending parallel to the ribs 11 between the ribs 11, 11 in a plan view of one surface side 20T of the nonwoven fabric 20. In each band region 16, a plurality of saddle portions 15 are arranged at intervals along the extension direction Y of the ribs 11 running in parallel. The above-mentioned openings 3 of the bottom portion 12 are located in the spaced apart portions of the saddle portions 15, and the raised portions 5 enter into them. That is, in each band region 16, the saddle portions 15, the openings 3, and the raised portions 5 are arranged alternately. As a result, the openings 3 and the raised portions 5 are surrounded and partitioned by the wall portions 11B of the ribs 11 and the wall portions 15B of the saddle portions 15. More specifically, the area surrounded by a plurality of ridges 11 and a plurality of saddles 15, which are three-dimensional fiber layers arranged in the thickness direction, is a box-shaped or cylindrical recess, with an opening 3 arranged at the bottom 12 and a protrusion 5 penetrating therein.

[0059] 3 to 6, in a plan view from one surface 20T of the nonwoven fabric 20, the ridges 11 and saddles 15 are arranged in a lattice pattern, and the openings 3 of the bottom 12 are arranged in a square pattern scattered within the lattice. The raised portions 5 of the second fiber layer M2 enter the lattice-shaped recessed spaces partitioned by the walls 11B and 15B from the openings 3 surrounded by the ridges 11 and saddles 15. Since the raised portions 5 of the second fiber layer M2 are surrounded by the walls 11B and 15B in a lattice pattern in this manner, the rapid liquid drawing ability and the liquid flow prevention ability described above are further enhanced, which is preferable. In addition, the four walls 11B and 15B surrounding the raised portion 5 have contact areas 4 with the second fiber layer M2, and valleys between the base portions 1D of the walls 11B and 15B and the bottom portions 7 of the raised portion 5 and the shadows caused by these valleys are formed on all four sides, so that the contours of the raised portion 5 and the openings 3 can be more clearly seen.

[0060] 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 5 and 6. This reduces the contact area with the skin on one surface side 20T of the nonwoven fabric 20, maintaining a pleasant feel against the skin, and increasing breathability to further prevent stuffiness between the surface and the skin. The difference (H3-H4) between the thickness direction height H3 of the rib portion 11 and the thickness direction height H4 of the saddle portion 15 is preferably 0.5 mm or more and 7 mm or less in order to improve the above-mentioned action. The thickness direction height H3 of the rib portion 11 is the thickness direction distance from 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 H4 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.

[0061] (Method of measuring the difference between the height H3 of the ridge portion 11 in the thickness direction and the height H4 of the saddle portion 15 in the thickness direction) As shown in FIG. 5, a thickness direction cross section (thickness direction cross section at the position of line R2-R2 in FIG. 3) 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 fabric is placed on a horizontal table so that the surface of the other side 20B of the second fiber layer M2 abuts against the horizontal table. The height H3 from the horizontal table to one side 20T of the crest 11A of the ridge portion 11 and the height H4 from the horizontal table to one side 20T of the crest 15A of the saddle portion 15 are measured. The height difference (H3-H4) is calculated from these measured values. The above-mentioned microscope can be used to measure the height from the horizontal table.

[0062] In addition, it is more preferable that the saddle portion 15 has a hollow region 15C as shown in FIG. 5 from the viewpoint of further promoting drainage of liquid to the other surface side 20B of the nonwoven fabric 20 when the nonwoven fabric 20 is used as a top sheet of an absorbent article. The definition and measurement method of this hollow region 15C are the same as those of the hollow region 11C in the ridge portion 11. It is preferable that the hollow region 15C of the saddle portion 15 communicates with the hollow region 11C of the ridge portion 11. This promotes the diffusion of excreted liquid on the other surface side 20B of the nonwoven fabric 20, 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.

[0063] Next, a preferred embodiment of a method for producing the nonwoven fabric 20 will be described with reference to Figures 7 to 10. The production method described below can also be applied to the production method for the nonwoven fabric 10. As shown in FIG. 7, the manufacturing method of this embodiment includes the following four steps (hereinafter, each step may be referred to as step (I), step (II), step (III), and step (IV)). (I) A pressing process in which a first fiber web 100 is placed on a support 120 having an uneven shape with a plurality of protrusions 121 and recesses 125 between the protrusions 121, 121, and the first fiber web 100 is pressed along the recesses 125 by a pressing portion 131 of a pressing member 130 to form a shape, and holes are opened at the locations corresponding to the protrusions 121, thereby forming an uneven open-hole fiber web 101 having an open surface on the opposite side to the support 120. (II) A step of removing the pushing member 130 from the support 120, and then blowing a first hot air W1 onto the porous fibrous web 101 to fuse the fibers together to obtain the porous nonwoven fabric 102. (III) A step of supplying the second fiber web 103 and laminating it onto the open-pore side of the unevenly perforated nonwoven fabric 102. (IV) A heat-sealing step of blowing a second hot air W2 to fuse the fibers of the porous nonwoven fabric 102 and the second fibrous web 103 together and to fuse the fibers in the second fibrous web 103 together.

[0064] The first fibrous web 100 is a precursor of the first fibrous layer M1 in the nonwoven fabric 20 and contains thermoplastic fibers. The second fibrous web 103 is a precursor of the second fibrous layer M2 in the nonwoven fabric 20 and contains 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 loosely entangled, and which does not have the shape retention of a sheet by itself. In other words, it is a fiber assembly before being made into a nonwoven fabric. Therefore, the mobility between fibers in the fiber web is high, and the deformation of the fiber web in the pushing process is high. Such first fiber web 100 and second fiber web 103 are each supplied from a carding machine (not shown) to a predetermined thickness.

[0065] In step (I), as shown in FIG. 7(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 a 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.

[0066] The support 120 is drum-shaped as shown in Fig. 7, for example, and has protrusions 121 as shown in Fig. 7(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. 8, for example. A plurality of protrusion rows 121A, each of which is formed by arranging a plurality of protrusions 121 in the first direction D1, are arranged at a distance from each other in the second direction D2. The protrusions 121 have peaks 122 at their tips. The peaks 122 form the openings 3 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. 8, 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 protrusion rows 121A, 121A, and a second recess 125C located between the protrusions 121, 121 in the protrusion row 121A. The second recess 125C is connected to the adjacent first recess 125A and extends intermittently in the second direction D2 via the first recess 125A.

[0067] In the support 120, a plurality of protrusions 121 are arranged corresponding to positions where the openings 3 are to be formed in the bottom portion 12 of the first fiber layer M1 of the nonwoven fabric 20. The second recesses 125C between the protrusions 121, 121 in the protrusion row 121A are located at positions where the saddle portions 15 of the first fiber layer M1 of the nonwoven fabric 20 are formed. In other words, the protrusion row 121A is located at a position that will become the band regions 16 between the ribs 11, 11 in the first fiber layer M1 of the nonwoven fabric 20. The first recesses 125A are located at a position that will become the ribs 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).

[0068] The pushing member 130 is in the form of a roll as shown in Fig. 7, for example, and has a pushing portion 131 as shown in Fig. 7(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. 9, 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.

[0069] 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 .

[0070] 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.

[0071] In step (I), the protrusions 121 of the support 120 are inserted into the recesses 132 of the pushing member 130. The pushing portions 131 of the pushing member 130 are inserted into the first recesses 125A of the support 120 (FIGS. 7(A) and 10). This pushing between the support 120 (FIG. 8) and the pushing member 130 (FIG. 9) 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 open portion 3 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 portion 131 does not enter. However, the pushing force of the pushing portions 131, 131 of the pushing member 130 acts on both sides of the fibers of the first fiber web 100 in the second recess 125C of the protrusion row 121A. Due to this action, the fibers of the first fiber web 100 in the second recess 125C are stretched in the second direction D2 by the pushing portions 131, 131 on both sides and pushed in the thickness direction, so that the fibers are shaped in the thickness direction and the fiber orientation changes. This portion becomes the saddle portion 15 in the first fiber layer M1 of the nonwoven fabric 20. The saddle portion 15 has an apex 15A and a wall portion 15B, and the wall portion 15B is similar to the wall portion 11B of the ridge portion 11.

[0072] 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.

[0073] Next, in step (II), after removing the pushing member 130 from the support 120, a first hot air W1 is blown onto the porous fibrous web 101 to fuse the fibers together to obtain a porous nonwoven fabric 102 (FIG. 7(B)). This porous nonwoven fabric 102 becomes the first fiber layer M1 of the nonwoven fabric 20. For example, the porous fibrous web 101 is rotated while being held on the support 120, and after passing through the meshing portion between the support 120 and the pushing member 130, the first hot air W1 is blown onto the porous fibrous web 101 at the position of the hot air blowing section 140 in FIG. 7(B). The support 120 preferably has a hot air suction section 141 at a position facing the hot air blowing section 140 inside the drum.

[0074] 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 1 m / s or more, and more preferably 2 m / s or more. Also, from the viewpoint of making the device scale compact, the wind speed of the first hot air W1 is preferably 100 m / s or less, and more preferably 80 m / s or less.

[0075] Next, in step (III), the second fibrous web 103 is supplied and laminated onto the open-hole side of the porous nonwoven fabric 102 (FIG. 7(C)). For example, the porous nonwoven fabric 102 formed by blowing the first hot air W1 is separated from the drum circumferential surface of the support 120 and transported downstream on a belt conveyer with the side on which the open holes 3 are formed by the protrusions 121 facing up, and the second fibrous web 103 is joined to the open-hole side and laminated.

[0076] Next, in step (IV), a second hot air W2 is blown in a fusion furnace 170 to fuse the fibers of the porous nonwoven fabric 102 and the second fibrous web 103 together and to fuse the fibers in the second fibrous web 103 together (FIG. 7(D)). This integrates the porous nonwoven fabric 102 and the second fibrous web 103 and also turns the second fibrous web 103 into a nonwoven fabric. This nonwoven fabric of the second fibrous web 103 becomes the second fiber layer M2 of the nonwoven fabric 20. At this time, as shown in Fig. 7(D), the porous nonwoven fabric 102 is placed on the net 180 with the side facing down, and the second hot air W2 is blown onto the second fiber web 103, so that the second fiber web 103 is pressed in. The pressed second fiber web 103 enters the openings 3 of the porous nonwoven fabric 102 into the regions partitioned by the walls 11B and 15B, and the protuberances 5 are formed. At the same time, the walls 11B and 15B of the porous nonwoven fabric 102 are integrated with the second fiber web 103 in the contact regions with the second fiber web 103, forming fiber fusion parts at the intersections between the fibers. The walls 11B and 15B are also pressed into the second fiber web 103. This biting is caused by the second hot air W2, and is performed while the shapes of the walls 11B and 15B are maintained. Moreover, due to the blowing process of the second hot air W2, the shapes (heights) of the walls 11B and 15B are easily maintained, and while the shapes (heights) are maintained, the walls 11B and 15B are closely and integrally attached to the second fiber web 103. In this manner, the second fiber layer M2 (the nonwoven product of the second fiber web 103) is closely attached to the entire surfaces (walls 11B, 15B, and apertures 3) of the uneven porous nonwoven fabric 102 (first fiber layer M1) and integrated therewith, thereby obtaining the nonwoven fabric 20 described above.

[0077] Taking into consideration the typical fiber materials used in this type of product, the temperature of the second hot air W2 is preferably 0°C to 70°C higher than the melting point of the thermoplastic fibers that make up the unevenly perforated nonwoven fabric 102 and the second fiber web 103, and more preferably 5°C to 50°C higher. The wind speed of the second hot air W2 is preferably 0.3 m / s or more, and more preferably 0.4 m / s or more, from the viewpoint of fusing the fibers in the second fibrous web 103 and from the viewpoint of sufficiently fixing the porous nonwoven fabric 102 and the second fibrous web 103. Moreover, from the viewpoint of further increasing the softness of the nonwoven fabric 20, the wind speed of the second hot air W2 is preferably 50 m / s or less, and more preferably 30 m / s or less.

[0078] 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. 9. 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.

[0079] 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. 9, 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 unevenly 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 wall 11B and the wall 15B of the first fiber layer M1 can be well maintained in the manufactured nonwoven fabric 20. This makes it possible to improve the cushioning properties and body pressure dispersion properties, the liquid flow prevention properties, and the visibility of the apertures 3 and the protrusions 5 in the nonwoven fabric 10.

[0080] 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 restrictions. For example, they may be fibers made of a single resin component or composite fibers made of multiple resin components. Composite fibers may have, for example, a core-sheath structure or a side-by-side structure. When using composite fibers containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air blown onto the fiber web in the manufacturing process is preferably equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component. More preferably, the temperature is equal to or higher than the melting point of the low melting point component and 10°C lower than the melting point of the high melting point component, and even more preferably, the temperature is 5°C or higher than the melting point of the low melting point component and 20°C or lower than the melting point of the high melting point component. In terms of elasticity, the more the core of the core-sheath structure composite fibers have, the higher the elasticity. Therefore, it is preferable that the core component is larger in terms of cross-sectional area ratio. A specific example of a composite fiber having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component is a composite fiber having a core-sheath structure in which the sheath is a polyethylene resin (hereinafter also referred to as PE) and the core is a polyethylene terephthalate resin (hereinafter also referred to as PET). Furthermore, in composite fibers with a core-sheath structure, when the resin component of the sheath has a lower glass transition point than the resin component of the core (hereinafter referred to as a low-glass transition point resin component; for example, the resin component of the core is PET and the resin component of the sheath is PE), the thickness recovery of the nonwoven fabric can be further improved by reducing the mass ratio of the low-glass transition point resin component.

[0081] The nonwoven fabric of the present invention can be used for various purposes. For example, it can be used as a component of various absorbent articles. 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.

[0082] 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

[0083] 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 column to the left. "-" means that there is no value or the like corresponding to that item.

[0084] [Example 1] The nonwoven fabric shown in Figs. 3 to 6 was produced by carrying out the steps below based on the production method shown in Fig. 7, and this was used as the nonwoven fabric sample of Example 1 (see Figs. 11 and 12). Specifically, the production was carried out according to the following procedure. In Fig. 12, in order to understand the shape of the raised portion 5, the surface of the second nonwoven fabric layer M2 facing the first nonwoven fabric layer M1 is shown with a dashed line. First, a first fiber web 100 was produced using thermoplastic fibers of a core-sheath type (polyethylene terephthalate (PET) / polyethylene (PE)=5:5) having a fiber diameter of 17 μm. The thermoplastic fibers were subjected to a hydrophilization treatment. The first fiber web 100 was placed on a support 120, and a pushing member 130 was pushed into the support 120 from above the first fiber web 100 to perform a shaping treatment. A first hot air W1 was blown to perform a fusion treatment, and an unevenly perforated nonwoven fabric 102 (first fiber layer M1) was produced. The first hot air W1 had a temperature of 160° C. and a wind speed of 3.0 m / sec. The unevenly perforated nonwoven fabric 102 produced, i.e., the basis weight, the open area and the open area ratio of the open hole portion 3 of the first fiber layer M1, were as shown in Table 1. Next, a second fiber web 103 made of thermoplastic core-sheath type (polyethylene terephthalate (PET) / polyethylene (PE)=5:5) fibers having a fiber diameter of 14 μm was laminated on the porous surface side of the uneven porous nonwoven fabric 102, and a second hot air W2 was blown thereon for fusion treatment to produce a laminated nonwoven fabric, which was used as a nonwoven fabric sample of Example 1. The second hot air W2 had a temperature of 160° C. and a wind speed of 1.3 m / sec. The basis weight of the second fiber layer M2 obtained from the second fiber web 103 was as shown in Table 1. The nonwoven fabric sample of Example 1 produced had a basis weight of 105 g / m 2In the nonwoven fabric sample of Example 1, the fibers of the wall portion 11B and the wall portion 15B of the first fiber layer M1 were longitudinally oriented. The second fiber layer M2 had protrusions 5 extending from the openings 3 into the region defined by the walls 11B and 15B. Weight of the entire nonwoven fabric sample of Example 1: 4.9 mN / cm 2 The thickness under load was as shown in Table 1. The "weight per unit area" was determined by measuring the area and mass of the nonwoven fabric stored for 24 hours or more in an environment of 23±2°C and a relative humidity of 50±5%. The "thickness" was determined by measuring the area and mass of the nonwoven fabric sample with a thickness of 4.9 mN / cm 2 (0.05gf / cm 2 The thickness was measured with a thickness measuring device under a load of 100 mm. A laser displacement meter manufactured by Omron Corporation was used as the thickness measuring device. Measurements were taken at 10 points, and the average value was calculated to determine the thickness.

[0085] [Examples 2 and 3] Nonwoven fabric samples of Examples 2 and 3 were prepared in the same manner as in Example 1, except that the basis weight of the second fibrous layer M2 obtained from the second fibrous web was set as shown in Table 1.

[0086] [Comparative Example 1] The top sheet of the commercially available "Relief Powerful Urine Absorbing Pad Wide Night Use No. 5" (product name, manufactured by Kao Corporation, manufactured in 2024) was used as the nonwoven fabric sample of Comparative Example 1 (see FIG. 13). As shown in Table 1, it was a fiber sheet with only one layer and no open holes. The basis weight and tensile strength of the nonwoven fabric sample of Comparative Example 1 were 4.9 mN / cm 2 The thickness under load was as shown in Table 1.

[0087] <Preparation of test samples> The top sheet was removed from the commercially available urine pad, and the nonwoven fabric samples of Examples 1 to 3 were laminated as top sheets, and attached with a hot melt adhesive to prepare test samples. 2 At that time, each nonwoven fabric sample was laminated so that the second fiber layer surface M2 side faced the absorbent body side of the urine pad. For Comparative Example 1, the commercially available urine pad was used as it was as a test sample. The following tests were carried out on each test sample.

[0088] <1> Urine absorption performance test: Liquid return amount First, an artificial urine having the following composition was prepared. (Composition) Urea 1.940% by mass, sodium chloride 0.795% by mass, magnesium sulfate 0.110% by mass, calcium chloride 0.062% by mass, potassium sulfate 0.197% by mass, Red No. 2 (dye) 0.010% by mass, water (96.886% by mass) Next, each prepared test sample urine pad was attached to a rubber model equivalent to an adult body type, with the waist of the urine pad fitting the crotch and the buttocks flap on the back being in close contact with the model. Next, 150 g of the artificial urine was injected over 30 seconds through a tube (for urine) attached to the model. 10 minutes after the start of injection, 150 g was injected again over 30 seconds. 10 minutes after the start of the second injection, 150 g was injected again over 30 seconds, for a total of 450 g of artificial urine. The temperature of the test atmosphere was room temperature (20±5°C), and the temperature of the artificial urine was room temperature (20±5°C). Ten minutes after the completion of injection, 16 sheets of Advantec filter paper No. 4A (100mm x 100mm) were stacked (mass measurement W1) and placed at the center of the longitudinal direction of the urine pad. A pressure of 4.5kPa was applied through a 5mm thick, 100mm x 100mm acrylic plate, and the mass of the filter paper was measured after 2 minutes (W2), and the amount of liquid returning was calculated based on the following formula. Amount of liquid returned (g) = Mass of filter paper after pressure (W2) - Initial mass of filter paper (W1) The above procedure was carried out three times, and the average of the three measurements was taken as the amount of liquid returning (g) for each test sample. The smaller the amount of liquid returning, the less likely it was to cause liquid returning, and the higher the evaluation.

[0089] <2> Soft stool absorption performance test First, artificial loose stool was prepared as follows. The composition ratio of bentonite (Kanto Chemical Co., Ltd., product number: 04066-01, standard: Grade 1 deer) 20%, Poise 530 (Kao Corporation) 0.5%, Emulgen 130K (Kao Corporation) 1.5%, and ion-exchanged water 78% was mixed using a digital mixer and adjusted to a viscosity of 40 cP (tuning fork vibration viscometer: A&D Co., Ltd., SV-10). Next, the following tests were carried out for model absorption evaluation: pad absorption amount and loose stool spreading area, and flat surface absorption evaluation: loose stool return amount and loose stool spreading area. (2-1) Model absorption evaluation: Pad absorption amount The prepared test sample urine pad was placed on an acrylic model equivalent to an adult body type. <1> In addition, a commercially available tape-fastened diaper (product name "Relief Crotch Leakage Prevention Tape Fastener M Size", Kao Corporation, manufactured in 2024) was worn over the urine-absorbing pad. Next, 200 g of simulated loose stool was injected over 10 seconds through a tube (for loose stool) attached to the model. Five minutes after the start of injection, a Kimtowel was used to wipe off the stool remaining (floating) on ​​the surface of the top sheet of the urine pad, the stool that had leaked from the urine pad and transferred to the tape-fastened diaper, and the stool (free stool) adhering to the model. The mass of the urine pad was measured (W2), and the amount of return liquid was calculated based on the following formula. Pad absorption capacity (g) = mass of urine pad after injection of artificial soft stool (W2) - mass of urine pad before injection (W1) The above procedure was carried out three times, and the average of the three measurements was recorded as the pad absorption amount (g) of each test sample. The greater the pad absorption amount, the less liquid adheres to the skin and the less likely leakage occurs, and the higher the evaluation. (2-2) Model absorption evaluation: soft stool diffusion area The artificial loose stool was injected in the same manner as in (2-1) above, and 5 minutes after the start of injection, the area on the surface sheet where the artificial loose stool had spread was transferred to an OHP sheet, scanned, and imported into Image-Pro to determine the loose stool spreading area. The measurement was performed three times, and the average value was taken as the loose stool spreading area for each test sample. The smaller the loose stool spreading area, the higher the rapid liquid absorption and liquid flow prevention properties, indicating that the liquid is less likely to adhere to the skin, and the higher the evaluation. (2-3) Plane absorption evaluation: amount of soft stool returned The above-mentioned test sample urine pads were unfolded and spread out flat, and 10 g of simulated soft stool was injected into each urine pad at a position 160 mm behind the longitudinal center over 6 seconds. 30 seconds after the injection was completed, 16 sheets of Advantech filter paper No. 4A (100 mm x 100 mm) were stacked (mass measurement W1) at the injection position of the urine pad. A pressure of 4.5 kPa was applied through an acrylic plate 5 mm thick and 100 mm x 100 mm. The mass of the filter paper was measured after 2 minutes (W2), and the amount of feces returned was calculated based on the following formula. Amount of feces returned (g) = Mass of filter paper after pressure (W2) - Initial mass of filter paper (W1) The above procedure was carried out three times, and the average of the three measurements was taken as the amount of returned feces (g) for each test sample. The smaller the amount of returned feces, the less likely it was to cause fecal return, and the higher the evaluation. (2-4) Planar absorption evaluation: soft stool diffusion area The soft feces was injected in the same manner as in (2-3) above, and 30 seconds after the injection was completed, the area on the surface sheet where the soft feces had spread was transferred to an OHP sheet, scanned, and imported into Image-Pro to determine the soft feces spreading area. The measurement was performed three times, and the average value was taken as the soft feces spreading area for each test sample. The smaller the soft feces spreading area, the higher the rapid liquid absorption and flow prevention properties, and the less likely the liquid was to adhere to the skin, which resulted in a higher evaluation.

[0090] The results of each of the above tests are shown in Tables 1 and 2 below.

[0091] [Table 1]

[0092] [Table 2]

[0093] As shown in Table 1, the nonwoven fabric sample of Example 1 is compared with the nonwoven fabric sample of Comparative Example 1. <1> Urine absorption performance test and <2> The results of the soft stool absorption performance test were good, and the nonwoven fabric samples of Examples 2 and 3 were excellent in terms of rapid liquid absorption, liquid flow prevention, and liquid backflow prevention. As shown in Table 2, the nonwoven fabric samples of Examples 2 and 3 were superior to the nonwoven fabric sample of Comparative Example 1 in terms of <2> The results of the planar absorption evaluation in the soft stool absorption performance test were good, and the nonwoven fabric samples were excellent in terms of preventing liquid backflow. As a result, it was confirmed that the nonwoven fabric samples of Examples 1 to 3 can reduce adhesion of liquid to the skin and suppress skin troubles compared to the nonwoven fabric sample of Comparative Example 1. In addition, it was confirmed that the nonwoven fabric samples of Examples 1 to 3 have a larger basis weight and thickness and a unique uneven structure compared to the nonwoven fabric sample of Comparative Example 1, so that they have good cushioning properties and excellent body pressure dispersion properties. [Explanation of symbols]

[0094] M1 First fiber layer M2 2nd fiber layer 1 Convex part 1A Top 1B Wall section 1C hollow area 1D Base 2 bottom 3 Opening part 5 Protuberance 10, 20 Nonwoven fabric 10T, 20T One side 10B, 20B other side

Claims

1. A nonwoven fabric for absorbent articles, comprising a first fiber layer and a second fiber layer laminated in a thickness direction, and including fused fiber portions at intersections between the fibers, the first fiber layer has a concave-convex structure including a plurality of convex portions and a bottom portion provided between adjacent convex portions, each of the plurality of convex portions includes an apex portion and a wall portion supporting the apex portion, and an opening portion penetrating through the bottom portion in a thickness direction is provided, The second fiber layer is provided on the side of the first fiber layer where the bottom portion is located, the second fiber layer has, on a surface facing the first fiber layer, a raised portion extending from the opening of the first fiber layer into a region defined by the wall portion, The nonwoven fabric for absorbent articles has a basis weight of 40 g / m ２ 120g / m or more ２ is as follows: The nonwoven fabric for absorbent articles has a strength of 4.9 mN / cm ２ The thickness under load is 5 mm or more and 15 mm or less, The opening area of ​​the opening is 20 mm ２ 35mm or more ２ is as follows: The opening rate of the opening portion of the nonwoven fabric for absorbent articles is 15% or more and 30% or less. Nonwoven fabric for absorbent articles.

2. The nonwoven fabric for absorbent articles according to claim 1 , wherein the raised portion is visible from the side of the first fibrous layer.

3. 3. The nonwoven fabric for absorbent articles according to claim 1, wherein the second fibrous layer has a surface facing the first fibrous layer, the surface being a continuous fibrous layer extending in a planar direction.

4. 3. The nonwoven fabric for absorbent articles according to claim 1, further comprising a fiber fusion portion at an intersection between the fibers of the wall portion and the fibers of the second fiber layer in a contact region of the wall portion of the first fiber layer and the fibers of the second fiber layer.

5. 3. The nonwoven fabric for absorbent articles according to claim 1, wherein the bottom of the raised portion is connected to a contact area between the wall portion of the first fiber layer and the second fiber layer.

6. 3. The nonwoven fabric for absorbent articles according to claim 1 or 2, wherein in the contact region between the wall portion of the first fiber layer and the second fiber layer, the fibers of the second fiber layer are oriented in a planar direction, and the fibers on the surface of the bottom portion of the raised portion have a fiber orientation different from that of the fibers of the wall portion.

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

8. 3. The nonwoven fabric for absorbent articles according to claim 1 or 2, which contains zinc oxide.

9. An absorbent article comprising the nonwoven fabric for absorbent articles according to claim 1 or 2.

Images