JP7754683B2 - Nonwoven fabric and its manufacturing method - Google Patents

Description

The present invention relates to a nonwoven fabric and a method for producing the same.

Conventionally, nonwoven fabrics have been provided with various types of uneven shapes, and manufacturing methods for providing such uneven shapes have been developed.
For example, Patent Document 1 describes a technique for forming a composite sheet by joining a first sheet and a second sheet made of a nonwoven fabric containing a resin material while shaping them by meshing concave and convex rolls together with heating. In the composite sheet obtained by this technique, the second sheet has a protrusion only in the center of the region corresponding to the curved portion of the first sheet, and the periphery is surrounded by a flat portion.

Patent documents 2 and 3 describe a technique for forming irregularities in an unfused web by blowing hot air onto it. In the nonwoven fabric obtained in this way, fiber orientation in the thickness direction is achieved in the irregularly shaped portions of the unfused web.

Patent Document 4 describes a technique in which a nonwoven fabric is laminated on an unfused web that has been shaped into unevenness by the meshing of uneven rolls, and then the unevenness is further shaped. The three-dimensionally shaped nonwoven fabric obtained by this technique has a two-layer structure with a closed hollow structure in which the inside of the convex portion of the surface fiber layer is hollow and a back fiber layer is laminated on the back side of the surface fiber layer.
Patent Document 5 describes a method for producing a nonwoven fabric by pressing a pressing section into an unfused fibrous web on a textured support to form the shaped web, and then laminating another unfused fibrous web on top of the pressed section. The resulting nonwoven fabric has a textured structure with varying heights.

Patent Document 6 describes a technique in which a nonwoven fabric made by heat-sealing thermoplastic resin fibers together is preheated, and then unevenly shaped using a pair of upper and lower stretching rolls that rotate while meshing with each other.
Patent Document 7 describes a technique in which a nonwoven fabric obtained by hot air treatment using an air-through method is subjected to uneven shaping, a laminated sheet having a lower layer containing heat-shrinkable fibers and an upper layer containing non-heat-shrinkable fibers is laminated, and hot air treatment for heat shrinkage is performed. In the sheet obtained in this way, the upper layer of the laminated sheet is raised by heat shrinkage of the heat-shrinkable fibers in the lower layer, forming solid interiors of the ridges, compared to the ridges of the unevenly shaped nonwoven fabric.

Japanese Patent Application Laid-Open No. 2019-063581 JP 2016-089289 A JP 2014-012913 A Japanese Patent Application Laid-Open No. 2021-037057 Japanese Patent Application Laid-Open No. 2019-112747 JP 2016-220986 A JP 2017-038838 A

In the sheet having a concave-convex structure described in Patent Document 1, the protrusions of the second sheet are not bonded to the curved portions (convex portions) of the first sheet, and further, the fiber components oriented in the thickness direction that contribute to crush resistance are small because they are only contained in the first sheet, which makes the space between the two sheets prone to crushing.
The nonwoven fabrics described in Patent Documents 2 and 3 have fiber orientation in the thickness direction by blowing hot air onto an unfused web to form an uneven shape. However, from the viewpoint of further improving cushioning properties and thickness retention, there is room for improvement in the fiber orientation. In addition, unfused fibers are easily displaced by the blowing of hot air during the manufacturing process, and there is room for improvement in order to maintain a sufficient thickness of the fiber layer of the shaped nonwoven fabric.
The nonwoven fabrics described in Patent Documents 4 and 5 have portions in which the unfused web is formed into a concave and convex shape by mechanical pressing, and by controlling the pressing amount in these portions, it is possible to obtain a higher fiber orientation and a thicker fiber layer than with a method using hot air blowing. On the other hand, in the nonwoven fabrics described in Patent Documents 4 and 5, there is room for improvement in the fiber structure between the upper and lower layers of the convex portions, from the viewpoint of further improving the thickness retention under pressure use. There is no particular mention of this point in Patent Documents 6 and 7.

In light of the above, the present invention relates to a nonwoven fabric that is soft and has good cushioning properties, yet has a bulky and thick fiber structure, can maintain its thickness when used under pressure, and is resistant to crushing.

The present invention provides a nonwoven fabric in which two or more fiber layers are laminated in the thickness direction, wherein a first fiber layer on one side has convex portions and concave portions, and a second fiber layer adjacent to the first fiber layer on the other side in the thickness direction has convex portions that extend into the convex portions of the first fiber layer on the other side, and at least interlayer fiber intersection fusion portions are included at the interface between the wall portions of the convex portions of the first fiber layer and the wall portions of the convex portions of the second fiber layer, the wall portions of the convex portions of the first fiber layer have a wall fiber orientation degree of 0.70 or more and 0.99 or less, and the ratio of the wall fiber orientation degree of the convex portions of the first fiber layer to the wall fiber orientation degree of the convex portions of the second fiber layer (former/latter) is 1.1 or more and 1.5 or less.

The present invention also provides a method for producing a nonwoven fabric, comprising: a first shaping step in which a first unfused web consisting of an aggregate containing fibers is shaped by engaging a support having convex or concave portions with a first pushing member having a pushing portion capable of engaging with the support; and a second shaping step in which a second unfused web is layered on the shaped first unfused web on the support, and shaped from the second unfused web side by engaging a second pushing member having a pushing portion capable of engaging with the support, wherein the ratio of the amount of engagement of the first pushing member with the support to the amount of engagement of the second pushing member with the support (former/latter) is 1.2 or greater; and during or after the second shaping step, a heat treatment step is performed in which the fibers are fused with a heated fluid, or embossed or fused.

The nonwoven fabric of the present invention is soft and has good cushioning properties, yet has a bulky and thick fiber structure that can maintain its thickness even when used under pressure and is resistant to crushing. Furthermore, the nonwoven fabric of the present invention can be suitably produced according to the manufacturing method for the nonwoven fabric of the present invention.

1 is a cross-sectional view schematically illustrating a preferred embodiment of the nonwoven fabric of the present invention. FIG. 1 is a cross-sectional view schematically showing another preferred embodiment of the nonwoven fabric of the present invention. FIG. 2 is a partially enlarged view of a cross section of the nonwoven fabric shown in FIG. 1. FIG. 10 is an explanatory diagram showing measurement positions of the wall fiber orientation degree. FIG. 1 is a cross-sectional view schematically showing various area ratios in the nonwoven fabric of the present invention. 1A and 1B are explanatory diagrams schematically illustrating two-stage interlocking shaping in the method for producing a nonwoven fabric of the present invention. FIG. 7 is a cross-sectional view schematically showing the stacked state of the first unfused web and the second unfused web after the two-stage meshing and shaping shown in FIG. 6, together with the convex portion of the support and the pushing portion of the pushing member. 10A and 10B are plan views showing different patterns in which the push-in portion of the first push-in member and the push-in portion of the second push-in member engage with each other in the planar direction of the support body. 9 is a cross-sectional view showing the relationship between the support body shown in FIG. 8 and the pushing portion of the first pushing member and the pushing portion of the second pushing member. 1 is a schematic diagram showing an example (Specific Example 1) of a preferred manufacturing apparatus used in the method for manufacturing a nonwoven fabric of the present invention. FIG. 2 is a schematic diagram showing another example (Specific Example 2) of a preferred manufacturing apparatus used in the method for manufacturing a nonwoven fabric of the present invention. Photographs (A) to (G) are drawings showing the state of the fiber layer observed when measuring the "total thickness under a load of 0.5 gf/ ^cm2 " of each of the nonwoven fabric samples of Examples 1 to 4 and Comparative Examples 1 to 3.

A preferred embodiment of the nonwoven fabric according to the present invention will be described below with reference to the drawings.
The nonwoven fabric of the present invention has two or more fiber layers laminated in the thickness direction, and has at least a two-layer structure such as nonwoven fabric 10 and nonwoven fabric 20 shown in Figures 1 and 2. Note that nonwoven fabric 20 shown in Figure 2 differs from the nonwoven fabric shown in Figure 1 only in that it has embossed portions 6 at the bottoms of the recesses, but the other fiber structures are the same. The matters detailed below regarding nonwoven fabric 10 shown in Figure 1 also apply to nonwoven fabric 20 shown in Figure 2.

The nonwoven fabric 10 of the embodiment shown in FIG. 1 has a first fiber layer 1 on one side 10A and a second fiber layer 2 adjacent to the first fiber layer 1 on the other side 10B in the thickness direction. The other side 10B refers to the side of the first fiber layer 1 opposite the one side 10A. The one side 10A and the other side 10B are also referred to as the front side 10A and the back side 10B. The front side 10A and the back side 10B refer to the front and back sides of the nonwoven fabric 10, as well as the front and back sides of each fiber layer. The front side 10A of the nonwoven fabric 10 can also be the side that comes into contact with the skin (skin-facing side).
1 is a laminate of two layers, a first fiber layer 1 and a second fiber layer 2, but is not limited thereto and may be a laminate of three or more layers. For example, another fiber layer may be laminated on the back side 10B of the second fiber layer 2 or on the front side 10A of the first fiber layer 1.

In the nonwoven fabric 10 of this embodiment, the first fiber layer 1 has protrusions 14 and recesses 15. The second fiber layer 2 has protrusions 24 that extend into the other surface 10B of the protrusions 14 of the first fiber layer 1. More specifically, the back surface 10B of the protrusions 14 of the first fiber layer 1 has a recessed shape toward the surface 10A, and the protrusions 24 of the second fiber layer 2 extend into these recesses. Both the protrusions 14 and the protrusions 24 have an arch shape with the back surface 10B recessed toward the surface 10A. The protrusions 14 and the protrusions 24 overlap in the thickness direction to form the arch-shaped protrusions 4 of the nonwoven fabric 10.
In the nonwoven fabric 10 of this embodiment, the recesses 15 of the first fiber layer 1 are arranged to overlap the recesses 25 of the second fiber layer 2 in the thickness direction. This forms the recesses 5 of the nonwoven fabric 10.
In the nonwoven fabric 10, the first fiber layer 1 and the second fiber layer 2 are overlapped in the thickness direction, forming convex portions 4 and concave portions 5, which are alternately arranged in the planar direction. The nonwoven fabric 10 as a whole has a structure in which the apparent thickness of the entire nonwoven fabric 10 is increased by having a convex-concave structure on the top and bottom connecting the front side 10A and the back side 10B of the laminated fiber layers 1 and 2. As long as the nonwoven fabric 10 has such a convex-concave structure, the first fiber layer 1 and the second fiber layer 2 may include intermediate ridges (e.g., intermediate height portions connecting convex portions) in addition to the convex portions and concave portions described above.

Such nonwoven fabric 10 has two thicknesses: actual thickness and total thickness.
The "actual thickness" refers to the shortest distance between each point on the front side 10A and the back side 10B of each fiber layer, and refers to the thickness of the layer area filled with fibers in each fiber layer. The direction of the line connecting the shortest distance is not necessarily perpendicular to the planar direction of the nonwoven fabric 10. This can also be said to be the thickness of each shaped fiber layer along a direction perpendicular to the extension direction V. Figure 1 shows the actual thickness D1 of the first fiber layer 1 and the actual thickness D2 of the second fiber layer 2.
The "total thickness", also referred to as apparent thickness, refers to the thickness between the front and back surfaces of the nonwoven fabric 10 measured by sandwiching the nonwoven fabric 10 between flat plates. The "total thickness" is understood as the thickness between the flat plates and includes both the thickness of the entire nonwoven fabric 10 and the thickness of each of the fiber layers 1 and 2. Figure 1 shows the total thickness T0 of the nonwoven fabric 10 in the initial state before pressing, the total thickness T1 of the first fiber layer 1, and the total thickness T2 of the second fiber layer 2.
The "total thickness" in the initial state before pressing is measured with a flat plate and a load of 0.5 gf/ ^cm2 applied to the surface side 10A. The "0.5 gf/ ^cm2 load" refers to a load sufficient to suppress fuzzing on the surface of the nonwoven fabric, and is a light load (a light load that is not sufficient to compress the thickness of the nonwoven fabric) necessary to properly measure the total thickness of the nonwoven fabric 10. An example of a 0.5 gf/ ^cm2 load (0.05 kPa load) is a circular plate with a diameter of 2.5 cm and a mass of 2.45 g used as the flat plate.

(Method for measuring the total thickness of a nonwoven fabric under a load of 0.5 gf/ ^cm2 )
The nonwoven fabric to be measured is cut into 10 cm x 10 cm pieces to prepare a measurement sample. Using a laser thickness meter (Omron Corporation, High-Precision Displacement Sensor ZS-LD80 (product name)), a 0.5 gf/ ^cm² load (0.05 kPa load) is applied to the first surface side of the measurement sample using a flat plate, and the thickness is measured in this state. Measurements are taken at three locations, and the average value is taken as the total thickness of the nonwoven fabric to be measured.
If the nonwoven fabric to be measured is incorporated into a product, the adhesive strength of the adhesive or the like is weakened by a cooling means such as a cold spray, and the nonwoven fabric is removed from the product before the above measurement is performed. This method of removing the nonwoven fabric is also applicable to other measurements in this specification.
If it is not possible to take out a nonwoven fabric measuring 10 cm x 10 cm, take out a piece as large as possible.
The total thickness under a high load (50 gf/cm ² load) described below can be measured by changing the load from 0.5 gf/cm ² to 50 gf/cm ² (5 kPa) in the above measurement method.

The thickness direction Z of the nonwoven fabric 10 is the direction of the thickness indicated by the "total thickness" and is a direction perpendicular to the planar direction N when the nonwoven fabric 10 is viewed in plan view. This is also referred to as the direction perpendicularly connecting the flat plate in contact with the top of the convex portion 4 and the flat plate in contact with the back surface of the bottom of the concave portion 5.
The extending direction V of the fiber layers is the direction in which the fiber layers are continuous as layers, and is the direction connecting the tops of the convex portions and the bottoms of the concave portions along the fiber layers. This means the direction rising at an angle with respect to the planar direction N.

The overlapping of the protrusions 14 of the first fiber layer 1 and the protrusions 24 of the second fiber layer 2 in the thickness direction includes at least interlayer fusion fiber intersections P, where fibers between the layers are bonded, at the interface between the wall portions 12 of the protrusions 14 of the first fiber layer 1 and the wall portions 22 of the protrusions 24 of the second fiber layer 2. In a cross section of the nonwoven fabric 10 in the thickness direction Z under a load of 0.5 gf/ ^cm² , as shown in Figure 3, the length in the thickness direction Z between the highest point E1 on the back side 10B of the protrusions 14 of the first fiber layer 1 and the lowest point E4 on the front side 10A of the recesses 25 of the second fiber layer 2 is defined as F. The length in the thickness direction Z of the interface between the layers at which interlayer fusion fiber intersections P, where fibers are bonded, exists is defined as G (the length in the thickness direction between points E5 and E4). These values are determined by a method similar to the method for measuring the void ratio (area ratio of voids 3), which will be described later.

The "wall portion" is a fiber layer portion that is specified as follows when the nonwoven fabric 10 is viewed along the vertical direction (thickness direction Z) connecting the flat plates described above under a load of 0.5 gf/ ^cm2 .
3 , the fiber layer portions within the range of lengths H1 and H2 in the thickness direction Z between the lowest points E3 and E4 on the front side 10A of each recess 15 and 25 and the highest points E1 and E2 on the back side 10B of each protrusion 14 and 24 are referred to as "wall portions." According to the above criteria, the wall portions 12 in the protrusions 14 of the first fiber layer 1 and the wall portions 22 in the protrusions 24 of the second fiber layer 2 are specified. In other words, the portion I where the lengths H1 and H2 in the thickness direction Z overlap includes at least a part or all of the interlayer fiber intersection fusion-bonded portions P, which are present at the interface between the wall portions 12 in the protrusions 14 of the first fiber layer 1 and the wall portions 22 in the protrusions 24 of the second fiber layer 2 and where the fibers of the respective layers are bonded to each other.

As shown in Figure 3, the first fiber layer 1 on the surface side 10A of the wall portion 12, as divided by the above criteria, is referred to as the top portion 11, and the first fiber layer 1 on the back side 10B of the wall portion 12 is referred to as the bottom portion 13. The bottom portion 13 includes a fiber layer disposed at the bottom of the recess 15 of the first fiber layer 1. Similarly, the second fiber layer 2 on the surface side 10A of the wall portion 22, as divided by the above criteria, is referred to as the top portion 21, and the second fiber layer 2 on the back side 10B of the wall portion 22 is referred to as the bottom portion 23. The bottom portion 23 includes a fiber layer disposed at the bottom of the recess 25 of the second fiber layer 2.

The "interlayer fiber intersection fused portion P" refers to a portion where fibers are thermally fused at their intersections by a fluid (hot air, steam, etc.). Such interlayer fiber intersection fused portions are formed when the first fiber layer 1 and the second fiber layer 2 contain thermoplastic fibers, and the thermoplastic fibers present at the interface between the layers are melted and bonded by the fluid. Note that in the first fiber layer 1 or the second fiber layer 2, the fiber intersection fused portions within the layer are referred to as "intralayer fiber intersection fused portions Q."

The interlayer fused fiber intersections P are included in the interface between the wall portions 12 of the convex portions 14 of the first fiber layer 1 and the wall portions 22 of the convex portions 24 of the second fiber layer 2. This firmly bonds and fixes the walls 12 and 22 together, and when the convex portions 4 of the nonwoven fabric 10 are deformed by pressure, they interfere with and support each other, making them less likely to collapse. That is, the pressure resistance of the convex portions 4 of the nonwoven fabric 10 is enhanced by the interlayer fused fiber intersections P. For the above reasons, the ratio (former/latter) of the length G in the thickness direction Z of the interface between each layer at which the interlayer fused fiber intersections P, where the fibers are bonded, exist to the length F in the thickness direction Z between the highest point E1 on the back surface of the convex portions 14 of the first fiber layer 1 and the lowest point E4 on the front surface of the concave portions 25 of the second fiber layer 2 is preferably 0.2 or more and 0.9 or less, more preferably 0.4 or more and 0.8 or less.
In the nonwoven fabric 10 shown in FIG. 1, the interfaces between the bottoms 13 of the first fiber layer 1 and 23 of the second fiber layer 2, which form the bottoms of the recesses 5, also contain fused fiber intersection points P between the layers, further enhancing the aforementioned pressure resistance.

Additionally, the wall fiber orientation degree in the walls 12 of the protrusions 14 of the first fiber layer 1 is 0.70 or more and 0.99 or less. This wall fiber orientation degree is a value measured by a method described below on a cross section of the protrusion in the thickness direction Z. A higher wall fiber orientation degree obtained by this measurement method indicates that more fibers are aligned in the extension direction V toward the tops 11 of the walls 12 (see FIG. 4 ).
By setting the wall fiber orientation degree to 0.7 or higher, the wall portions 12 connecting the tops 11 and bottoms 13 of the projections 14 have high pressure resistance against pressure from the tops 11. This improves the thickness and shape retention of the projections 4 of the nonwoven fabric 10. Furthermore, when the wall fiber orientation degree is 1, the fibers are aligned in one direction, reducing the probability of fiber intersections. In other words, the density of fiber fusion points is reduced. A high wall fiber orientation degree aligns the fibers in the extension direction V, increasing the stiffness component due to the fibers themselves in the extension direction V. However, conversely, the reduced probability of fiber intersections reduces the density of the fused heat-intersection points in each layer. In contrast, in this embodiment, in order to increase the overall rigidity of the nonwoven fabric, the wall fiber orientation degree in the wall portions 12 is set to 0.99 or less, thereby increasing the orientation of the fibers in the extension direction V and the probability of fiber intersections, thereby favorably increasing the density per unit volume of the fused heat-intersection points in each layer. This provides the wall portion 12 with high deformability and high rigidity when the protrusions 14 are compressed. The protrusions 14 of the first fiber layer 1 supported by the wall portion 12 are soft to the touch and have good thickness and shape retention, without becoming too hard. That is, the protrusions 14 of the first fiber layer 1 have a firm presence and a stable thickness, while still providing a soft feel due to the arched shape of the fiber network structure.
From this viewpoint, the wall fiber orientation degree of the walls 12 of the convex portions 14 of the first fiber layer 1 is preferably 0.73 or more, more preferably 0.75 or more, and even more preferably 0.78 or more. The wall fiber orientation degree of the walls 12 of the convex portions 14 of the first fiber layer 1 is preferably 0.95 or less, more preferably 0.90 or less, and even more preferably 0.81 or less.

In addition, the ratio of the wall fiber orientation degree of the convex portions 14 of the first fiber layer 1 to the wall fiber orientation degree of the convex portions 24 of the second fiber layer 2 (former/latter) is 1.1 or more and 1.5 or less. This means that the fibers of the walls 12 of the convex portions 14 of the first fiber layer 1 are more aligned in the wall extension direction V than the walls 22 of the convex portions 24 of the second fiber layer 2. When the ratio to the wall fiber orientation degree is 1.1 or more, the first fiber layer 1 deforms softly with a low load in the initial deformation when compressed. Furthermore, when the ratio to the wall fiber orientation degree is 1.5 or less, the second fiber layer 2 is compressed with high rigidity and rebounds when pressed. In other words, the convex portions 14 of the first fiber layer 1 have improved softness and thickness shape retention, while the convex portions 24 of the second fiber layer 2 have a relatively diverse fiber orientation direction and thus have thickness recovery ability. The convex portions 24 of the second fiber layer 2 conform to the shape of the convex portions 14 of the first fiber layer 1, supporting them from the inside while providing elasticity, and thus functioning as a cushion for the convex portions 4 (convex portions 14 + convex portions 24). In particular, when the wall fiber orientation ratio is 1.1 or more, the hardness of the nonwoven fabric 10 can be reduced, thereby enhancing the soft cushioning properties. Furthermore, when the wall fiber orientation ratio is 1.5 or less, the thickness of the nonwoven fabric 10 can be easily maintained and it is less likely to be crushed.
In this respect, the ratio is preferably equal to or greater than 1.2 and is preferably equal to or less than 1.4.

The nonwoven fabric 10 has the above-described fiber structure, which allows the fiber layers to have soft deformability while easily maintaining a thickness shape under pressure. Furthermore, during the production of the nonwoven fabric 10, the first fiber layer 1 is shaped by the intermeshing described below. This shaping prevents excessive compressive force from being applied to the unfused web, prevents the fiber density within each layer from being excessively high, and forms a mesh structure with fibers appropriately spaced apart. The nonwoven fabric 10 has such a mesh structure on the surface side 10A, which allows it to be bulky and thick. That is, the nonwoven fabric 10 has a bulky and thick fiber structure while having soft and good cushioning properties, and the thickness can be maintained under pressure and is resistant to crushing.
In addition, as described above, the first fiber layer 1 of the nonwoven fabric 10 is prone to deformation even with a weak force. Therefore, the second fiber layer 2 maintains the irregularities of the nonwoven fabric 10, while the first fiber layer 1 absorbs the irregularities by its deformation, thereby reducing the uneven feeling when touching the front side 10A of the nonwoven fabric 10 and simultaneously improving the smoothness when stroking the surface of the convex portions 14. This allows the nonwoven fabric 10 to combine thickness shape retention and smoothness in an irregular structure, which have traditionally been difficult to achieve.

(Method for measuring wall fiber orientation degree and wall fiber orientation angle)
The wall fiber orientation degree of the convex portions 14 of the first fiber layer 1, the wall fiber orientation degree of the convex portions 24 of the second fiber layer 2, and the wall orientation angle described below can be measured by the following method.
(1) The sample is cut in an arbitrary planar direction using sharp scissors. The cutting position is set so that it passes through the top of the convex portion 4 on the sample and the center of the concave portion 5 adjacent to the convex portion 4. When the sample is cut in a direction parallel to the CD direction, the cross section is taken in the CD direction. When the sample is cut in the MD direction or diagonal direction, the cross section is taken in the respective direction. Note that MD is the machine direction in the manufacturing process of the nonwoven fabric, and CD is the direction perpendicular to the MD (cross direction).
(2) The sample is cut into a rectangle so that each side contains at least five convex portions, thereby preparing a cross-sectional sample. The target concave/convex portion is observed at a position at least one convex portion inside the cut position of the corner of the sample. If the target nonwoven fabric is bonded to another layer, it is observed while still bonded to the other layer.
(3) Place the cross-sectional sample on a flat plate with the convex surface (front side) facing up, and place another flat plate on top of the cross-sectional sample so that the pressure is 0.5 gf/ ^cm² . Place the cross-sectional sample so that its cross section coincides with the end faces of both flat plates.
(4) Next, the cross section of the cross-sectional sample is observed from the side. Using a microscope, the observation magnification is 100x to 400x, quick composition (depth up, quick composition & 3D) is performed, the sample is moved from the back to the front, observation is performed, and an image is taken. As an example of the microscope, a VHX-6000 (product name) manufactured by Keyence Corporation is used.
(5) Using the image obtained by observation, the following measurements are carried out.
In the wall of the convex portion to be observed in the image, a square E is marked at a midpoint L1 in the direction of the actual thickness of each fiber layer (a direction perpendicular to the extending direction V of each fiber layer in the wall) S, and at midpoints (M1, M2) along lengths H1, H2 in the thickness direction Z between the lowest points E3, E4 on the front side 10A of each concave portion 15, 25 and the highest points E1, E2 on the back side 10B of each convex portion 14, 24 (see Figures 3 and 4). The size of the square E is smaller than the actual thickness and is large enough to accommodate five or more fibers. The size of the square E may differ between the first fiber layer 1 and the second fiber layer 2. The square E is tilted so that one side is parallel to the extending direction V of each fiber layer (a direction perpendicular to the actual thickness).
The fibers within square E are traced to extract the fibers that cross from one side to the other. At this time, fibers that cross only one side and are broken along the way are excluded.
A/(A+B) is calculated from the number A (total of two sides) of fibers intersecting the side EA of the square E, which is perpendicular to the extension direction V of the fiber layer, and the number B (total of two sides) of fibers intersecting the side EB of the square E, which is parallel to the extension direction V of the fiber layer. This value is the wall fiber orientation degree of the convex portion of each fiber layer. A higher wall fiber orientation degree means that the fibers are more oriented in the extension direction V of the fiber layer.
The direction perpendicular to the plane of the nonwoven fabric (the direction of the entire thickness) is set to 90 degrees, and the plane direction is set to 0 degrees, and the inclination angle of the side EB of the square E that is parallel to the extending direction V of the fiber layer is calculated. This value is the orientation angle of the fiber layer in the wall portion (hereinafter also referred to as the wall portion fiber orientation angle).
Each value is the average value of five points using different sample sides.
(6) The boundary between the laminated first fiber layer 1 and second fiber layer 2 can be identified by differences in layer structure, such as differences in fiber diameter, fiber orientation, fiber cross-sectional shape, voids between layers, fiber density, number of fibers per unit area, and basis weight.
(7) The total thickness of each fiber layer is calculated as follows. First, the boundaries on the front and back sides of each fiber layer are determined based on the difference described above. For example, when using the number of fibers, the boundary at the interface between fiber layers (or spaces) where the number of fibers in each fiber layer is half that of the center of the fiber layer is drawn as an outline. As the resolution, a square grid is drawn where one pitch is 1/50 of the total thickness of the nonwoven fabric, and the number of fibers within each square is counted. The boundary is determined by smoothing and connecting the squares where the number of fibers is more than half and less than half the average number of fibers in the center of each fiber layer. Note that if there are any locations within the fiber layer where the number of fibers is less than half, they are excluded from the boundary line. The region formed between the boundary between the first fiber layer 1 and the second fiber layer 2 is defined as the void region 3.
Next, two straight lines are determined on the sample surface side of the upper and lower flat plates of the sample in the cross section of the sample. The average distance between these two straight lines in the thickness direction of the nonwoven fabric is determined, and this is defined as the total thickness T0 of the nonwoven fabric 10.

The nonwoven fabric 10 of this embodiment having the above-described fiber structure can only be obtained by the manufacturing method described below, and cannot be obtained by conventional uneven shaping techniques. In particular, conventional hot air pressing cannot achieve a wall fiber orientation degree as high as that of the wall portions 12 of the convex portions 14 of the first fiber layer 1. Furthermore, the above-described wall fiber orientation ratio is difficult to achieve by conventional methods of stretching and shaping two layers after laminating them, or by shaping the two layers with the same intermeshing amount. Furthermore, if the second fiber layer 2 is simply laminated without shaping, the wall orientation ratio will exceed 1.6, and the nonwoven fabric 10 of this embodiment cannot be obtained.
The above-described wall orientation ratio in the nonwoven fabric 10 of this embodiment is obtained by mechanically pressing the web with different intermeshing amounts with specific differences in the manufacturing method described below. The difference in intermeshing amounts results in a difference in the stretch ratio relative to the unfused web to be processed. The higher the stretch ratio, the more irregular the unfused web becomes, resulting in a higher fiber orientation degree in the wall portion. Furthermore, in this shaping process using mechanical intermeshing, in addition to the difference in stretch ratio, differences in the amount of return of the fiber structure after shaping due to intermeshing occur between the unfused webs. That is, a higher stretch ratio tends to result in a smaller amount of return of the fiber structure after shaping. Therefore, the second unfused web 200 that becomes the second fiber layer 2 follows the first unfused web 100 that becomes the first fiber layer 1, but this return results in a lower fiber orientation degree. Taking these relationships into consideration, the above-described wall orientation ratio in the nonwoven fabric 10 of this embodiment can be imparted by mechanically pressing the web with different intermeshing amounts with specific differences in the manufacturing method described below.

The total thickness (T0) of the nonwoven fabric 10 in its initial state before compression (under a load of 0.5 gf/ ^cm2 ) is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more, from the viewpoint of increasing the amount of deformation due to pressure and providing a softer feel. Furthermore, the total thickness (T0) of the nonwoven fabric 10 under a load of 0.5 gf/ ^cm2 is preferably 15 mm or less, more preferably 10 mm or less, and even more preferably 6 mm or less, from the viewpoint of preventing the tendency for the nonwoven fabric 10 to be easily crushed when pressed, because if the total thickness is too high, the basis weight of each fiber layer will be low and the nonwoven fabric 10 will be easily crushed when pressed.

Furthermore, the nonwoven fabric 10, having the first fiber layer 1 and the second fiber layer 2, is more likely to maintain a thicker total thickness (TM) under a high load (50 gf/ ^cm² ) that is expected during use. This prevents the nonwoven fabric 10 from collapsing even under a high load, and it feels like it has less plastic deformation (sagging). This, combined with the total thickness (T0) in the initial state before compression (0.5 gf/ ^cm² ), gives the fabric a sense of stable thickness and cushioning, resulting in an excellent texture.
From this viewpoint, the total thickness (TM) of nonwoven fabric 10 under a high load (under a load of 50 gf/cm ² ) is preferably equal to or greater than 0.5 mm, more preferably equal to or greater than 0.7 mm, and even more preferably equal to or greater than 1.0 mm.
Furthermore, the total thickness (TM) of nonwoven fabric 10 under a high load (50 gf/ ^cm2 load) is preferably smaller than the total thickness (T0) in the initial state before pressing (0.5 gf/ ^cm2 load), in order to increase the amount of deformation due to pressure (T0-TM) and provide a softer feel. From this viewpoint, the total thickness (TM) is preferably 10 mm or less, more preferably 6 mm or less, and even more preferably 3 mm or less.

In the nonwoven fabric 10 of this embodiment, it is preferable that within the protrusions 4 having the specific structure related to the wall fiber orientation degree, an appropriate amount of voids 3 are present between the first fiber layer 1 and the second fiber layer 2. The voids 3 referred to here are areas with an extremely small amount of fiber compared to the first fiber layer 1 and the second fiber layer 2, and can be defined as regions where the fiber density of the voids 3 is 10% or less when the lower fiber density of the protrusions (and further the central portion in the thickness direction) of each fiber layer is taken as 100%, and are preferably spaces free of fibers.
This forms a primary storage space for bodily fluids and the like within the protrusions 4. For example, when the nonwoven fabric 10 is used as a topsheet that comes into contact with the skin in an absorbent article, the absorbency of the absorbent article can be improved and the dryness of the skin surface can be improved. Furthermore, when the voids 3 are present at an appropriate size, the nonwoven fabric 10 is soft under low loads in the early stages of deformation (for example, a load range of 0.5 gf/ ^cm2 to 10 gf/ ^cm2 ), but is less likely to be crushed under high loads (for example, a load range of ¹⁰ gf/ ^cm2 to 50 gf/cm2) due to the contribution of the underlying second fiber layer 2.
From the above viewpoints, in a cross section in the thickness direction along a line including the center of a convex portion (the top of a convex portion) and the center of a concave portion adjacent to the convex portion, obtained by the method for measuring void ratio described below, the void ratio (area ratio of voids 3) between the first fiber layer 1 and the second fiber layer 2 is preferably 4% or more, more preferably 6% or more, and even more preferably 8% or more, from the viewpoint of increasing the deformability of the nonwoven fabric 10 under pressure and making it feel softer. Furthermore, from the viewpoint of making the entire thickness of the nonwoven fabric 10 less likely to collapse under high load, the void ratio is preferably 13% or less, more preferably 10% or less. Note that, if the nonwoven fabric 10 has the aforementioned intermediate rib portions, it is preferable that no voids 3 are present in the intermediate rib portions.

The above void ratio can be appropriately set by controlling the amount of meshing in the manufacturing process described below. That is, from the perspective of having an appropriate amount of void space 3 between the first fiber layer 1 and the second fiber layer 2, it is preferable that the nonwoven fabric 10 have the above-mentioned ratio of the wall fiber orientation degree in the convex portions 14 of the first fiber layer 1 to the wall fiber orientation degree in the convex portions 24 of the second fiber layer 2.

(Method for measuring void ratio)
(1) The nonwoven fabric to be measured is cut with scissors or the like to obtain a sample. If the nonwoven fabric is bonded to other members (for example, if it is incorporated as a component of an absorbent article), the sample is taken while still bonded to the other members. The nonwoven fabric is placed in an unloaded state with the convex part facing up, and stored at a temperature of 23±2°C and a humidity of 65±5% RH for 48 to 72 hours.
(2) The sample is prepared into a rectangular shape with a size of 5 times the convex pitch (on the side of cut line 1) × 5 times the convex pitch. In this case, when viewed in plan, one side of the nonwoven fabric is cut in the thickness direction (cut line 1) with sharp scissors or the like, along a line that includes the center of the convex to be observed (the top of the convex) and the center of the concave adjacent to the convex. The direction of cut line 1 can be the MD direction, CD direction, or a diagonal direction. The cross section of cut line 1 is colored with a marker or the like.
(3) Observe the cross section of the unevenness from the cross section sample along the cut line 1. Place the cross section sample on a flat plate with the convex portion 4 facing up, and place a weight on top of it so that the load is 0.5 gf/ ^cm2 . At this time, the position of the sample cross section and the edge face of each plate are aligned.
(4) The cross section of the sample is observed from the side using a microscope (for example, VHX-6000 (product name) manufactured by Keyence Corporation). Three convex portions 4 and four concave portions 5 located in the center of the sample along the cut line 1 are observed at a magnification of 50 to 300 times.
(5) Using the observed image, the boundaries of the first fiber layer 1 and the second fiber layer 2 are drawn using the colored portions as a guide. If it is difficult to distinguish between the fiber layers, the boundaries are determined by the method described above in (Method for measuring the wall fiber orientation degree and wall fiber orientation angle).
(6) In the observed image, the boundaries of each fiber layer are filled in black, and the remaining areas are white. Image analysis software (for example, Image-Pro Plus (version: 6.2.0.424)) is used to determine the area A (observation range) between the upper and lower flat plates (plates) within the width of the observed image (for example, the area defined by the two-dot chain line frame indicated by symbol A in the cross section shown in Figure 5). The resolution of the image analysis software is set to 300 pixels/inch, and the size of the observed image is adjusted so that area A is 100,000 to ^200,000 pixels2.
(7) In the cross-sectional region having the area A, the areas of the void 3 formed between the rear boundary line of the first fiber layer 1 and the front boundary line of the second fiber layer 2, the gap 18 formed between the first fiber layer 1, the second fiber layer 2, the front boundary line of the first fiber layer 1 and the upper plate, and the gap 28 formed between the rear boundary line of the second fiber layer 2 and the stage are similarly determined (see, for example, FIG. 5).
(8) The void ratio (area ratio of voids 3) is calculated as follows: Area of voids 3/Area A x 100 (%). The area ratios of the gaps 18, the first fiber layer 1, the second fiber layer 2, and the gaps 28 are calculated in the same manner.
(9) Each value is the average value of five points using different sample sides.

When the nonwoven fabric 10 of this embodiment has a total thickness of 0.5 mm or more under a high load (50 gf/ ^cm² ) and an appropriate void area ratio of 4% to 13%, the convex portions 4 deform with gentle force under a low load (e.g., 10 gf/ ^cm² ). On the other hand, under a high load, the void portions 3 collapse, and the second fiber layer 2 compensates for the second fiber layer 1, making the entire convex portions 4 less likely to collapse. That is, the nonwoven fabric 10 can further maintain its thickness and become less likely to collapse under pressure. As a result, due to the above-described deformation behavior, the nonwoven fabric 10 is soft at the initial stage of compression, and then the second fiber layer 2 compensates for the first fiber layer 1 to make it less likely to collapse, resulting in an excellent texture. Furthermore, due to the difference in the wall fiber orientation between the first fiber layer 1 and the second fiber layer 2, the nonwoven fabric 10 exhibits softness and good cushioning properties with thickness recovery after compression.

With regard to the void ratio (area ratio of voids 3) measured by the above-mentioned (method for measuring void ratio), it is preferable that the value of "void ratio (area ratio of voids 3) / (total area ratio of gaps 18, voids 3, and gaps 28)" be 0.08 or more and 0.20 or less. This ensures that when the convex portions 4 of the nonwoven fabric 10 are crushed under a high load, the voids 3 are crushed first, and at this time, the second fiber layer 2 compensates for the first fiber layer 1, making the entire convex portions 4 even more resistant to crushing. A value of 0.08 or more is preferable because it ensures that a portion can be deformed by a soft force in the section from the start of pressure application until the voids 3 disappear. Furthermore, a value of 0.20 or less is preferable because it ensures that the rigidity of the first fiber layer 1 is not too low, resulting in a cushioning effect that provides a sense of security.
From this viewpoint, the value of "void ratio (area ratio of void portion 3)/(total area ratio of gap 18, void portion 3 and gap 28)" is more preferably 0.10 or more.
Furthermore, the value of "void ratio (area ratio of void portion 3)/(total area ratio of gap 18, void portion 3 and gap 28)" is more preferably 0.16 or less.

Furthermore, the nonwoven fabric 10 of this embodiment undergoes a manufacturing method described below that imparts a unique structure related to the wall fiber orientation degree, thereby increasing the thickness of the fiber layer itself in the thickness direction (total thickness direction). That is, the area ratio of the fiber layer in the thickness direction cross section of the uneven structure is increased, and the area ratios of the gaps 18, gaps 28, and voids 3 described above are suitably reduced. As a result, the nonwoven fabric 10 becomes bulky and thick in the areas where the fibers are present, further improving cushioning properties and thickness retention.
The area ratio of the fiber layers is expressed as "area ratio of the first fiber layer 1 + area ratio of the second fiber layer 2," measured by the above-mentioned (method for measuring void ratio). If the basis weight and total thickness T0 of the entire nonwoven fabric are the same, a larger value of this area ratio indicates a flatter shape with fewer irregularities and a lower bulk density of each fiber layer. A lower bulk density indicates a higher bulk. Conversely, a smaller value indicates a higher irregularity and a higher bulk density of each fiber layer. In other words, the larger the "area ratio of the first fiber layer 1 + area ratio of the second fiber layer 2," the bulkier the nonwoven fabric 10 will be in the regions occupied by the fibers, while still having an irregular structure.
The larger the "area ratio of the first fiber layer 1 + the area ratio of the second fiber layer 2," the bulkier the nonwoven fabric 10, and adjusting the "area ratio of the first fiber layer 1 + the area ratio of the second fiber layer 2" within a specific range improves cushioning properties. From this perspective, the "area ratio of the first fiber layer 1 + the area ratio of the second fiber layer 2" is preferably 36% or more, and more preferably 40% or more.
Furthermore, the "area ratio of the first fiber layer 1 + the area ratio of the second fiber layer 2" is preferably 60% or less, and more preferably 50% or less, from the viewpoint of making the laminate of the first fiber layer 1 and the second fiber layer 2 have a high bulk density in the area occupied by the fibers despite having an uneven structure, and from the viewpoint of making it difficult to crush.

In the nonwoven fabric 10 of this embodiment, the ratio of the fiber density at the tops of the protrusions 24 of the second fiber layer 2 to the fiber density at the tops of the protrusions 14 of the first fiber layer 1 (the former/the latter) is preferably 0.8 or more, more preferably 1.0 or more, from the viewpoints of improving the soft feel on the surface side 10A and enhancing liquid absorbency through the difference in density. This allows the interfiber distance in the first fiber layer 1 to be increased without changing the fiber diameter, thereby improving liquid permeability. Therefore, it is not necessary to increase the fiber diameter to achieve a coarse/dense fiber, and the interfiber feel can be improved. This is because, in the manufacturing method described below, a higher draw ratio due to intermeshing increases the interfiber distance and decreases the fiber density. That is, the intermeshing amount with the first unfused web 100 forming the first fiber layer 1 is greater than the intermeshing amount with the second unfused web 200 forming the second fiber layer 2, resulting in a higher draw ratio. As a result, the interfiber distance and fiber density of the resulting first fiber layer 1 are longer than those of the second fiber layer 2.
The ratio is preferably 1.8 or less, more preferably 1.5 or less, from the viewpoint of preventing the first fiber layer 1 from becoming too sparse and suppressing the generation of fluff on the surface side 10A.

(Method for measuring fiber density)
Using a scanning electron microscope (SEM), the sample is subjected to the minimum necessary amount of gold sputter deposition at a magnification of 100 to 700 times.
In the cross section prepared by the above (method for measuring void ratio), the number of cut fiber ends is counted at the center of the actual thickness of each layer and at the convex portion of each fiber layer. The measurement range is a square with one side measuring 50% to 80% of the actual thickness of each layer. The fiber cross section is divided by the area of the square to determine the fiber density (fibers/ ^mm2 ).
Each value is the average value of five points using different sample sides.

In the nonwoven fabric 10 of this embodiment, the wall fiber orientation angle of the convex portions 14 of the first fiber layer 1 is preferably larger than the wall fiber orientation angle of the convex portions 24 of the second fiber layer 2. This makes the uneven structure of the nonwoven fabric 10 even more resistant to collapse in the portions where the fibers rise from the bottom of the concave portions 5 to the top of the convex portions 4.
From this viewpoint, the difference between the wall fiber orientation angle of the convex portions 14 of the first fiber layer 1 and the wall fiber orientation angle of the convex portions 24 of the second fiber layer 2 (the former - the latter) is preferably 0 degrees or more, more preferably 12 degrees or more, and even more preferably 25 degrees or more. Having a suitable difference facilitates the provision of an appropriate amount of the voids 3. Furthermore, by increasing this difference, the gaps 28 on the back surface side 10B of the second fiber layer 2 can be reduced. This reduces the compression energy in the nonwoven fabric 10, making the nonwoven fabric 10 softer and less likely to feel stiff.
The difference between the wall fiber orientation angle of the convex portions 14 of the first fiber layer 1 and the wall fiber orientation angle of the convex portions 24 of the second fiber layer 2 (the former minus the latter) is preferably 50 degrees or less, more preferably 45 degrees or less, and even more preferably 40 degrees or less. By reducing this difference, the aforementioned voids 3 can be formed with an appropriate size, thereby reducing the gaps 18 on the surface side 10A of the first fiber layer 1. Furthermore, the number of interlayer fiber intersection fusion-bonded portions P at the boundary between the first fiber layer 1 and the second fiber layer 2 is also increased. As a result, the compression energy of the nonwoven fabric 10 does not become too small in the low load range from 0.5 gf/ ^cm² to 10 gf/ ^cm² , and the nonwoven fabric 10 has an appropriate hardness.
The wall fiber orientation angle is measured by the above-mentioned (Method of measuring wall fiber orientation degree and wall fiber orientation angle).

In the nonwoven fabric 10 of this embodiment, from the viewpoints of achieving bulkiness and thickness, of being resistant to crushing in the thickness direction, of having voids 3 of an appropriate size interposed therebetween, and of having softness and good cushioning properties, it is preferable that the basis weights of the first fiber layer 1 and the second fiber layer 2 be within the following ranges, respectively.
The basis weight of the first fiber layer 1 is preferably 5 g/m ^{or more} , more preferably 10 g/m ^{or more} , and even more preferably 15 g/m ^{or more} . The basis weight of the first fiber layer 1 is preferably 50 g/m ^{or less} , more preferably 40 g/m ^{or less} , and even more preferably 30 g/m or ^less .
The weight of the second fiber layer 2 is preferably 5 g/m or ^more , more preferably 7 g/m or ^more , and even more preferably 10 g/m or ^more . The weight of the second fiber layer 2 is preferably 45 g/m ^{or less} , more preferably 35 g/m or ^less , and even more preferably 25 g/m or ^less .

(Method for measuring basis weight of each fiber layer)
The area of the sample (the area of the sample when viewed in plan) is measured in advance, and each fiber layer is peeled off to measure the mass of each fiber layer. The mass is then divided by the area of the sample to determine the basis weight of each fiber layer.

By virtue of the structure described above, the nonwoven fabric 10 of this embodiment has the excellent friction, roughness, and compression properties described below.

[Friction characteristics]
The nonwoven fabric 10 has a moderate friction, which allows it to feel comfortable to the touch. From this viewpoint, the mean coefficient of friction (MIU) is preferably 0.1 or more, and more preferably 0.2 or more. This allows it to have a soft fibrous feel, rather than a smooth film-like feel. Furthermore, from the viewpoint of not feeling like the fabric is sticking to the skin and not damaging the skin, the mean coefficient of friction (MIU) is preferably 0.5 or less, and more preferably 0.4 or less.

Nonwoven fabric 10 can be perceived as having a pleasant feel when it has an appropriate level of smoothness. When the mean coefficient of friction (MIU) is within the appropriate range and the mean deviation of the coefficient of surface friction (MMD) is small, it tends to be perceived as being appropriately smooth. From this perspective, the mean deviation of the coefficient of surface friction (MMD) is preferably 0.001 or more, and more preferably 0.002 or more. Furthermore, the lower the friction, the less likely it is to get caught on an uneven surface, and the smaller the fluctuation in the coefficient of friction, making it feel smoother. From this perspective, the mean deviation of the coefficient of surface friction (MMD) is preferably 0.01 or less, and more preferably 0.008 or less.

(Method for measuring frictional characteristics)
The mean coefficient of friction (MIU) and the mean deviation of the surface friction coefficient (MMD) can be measured by the following method. That is, using an automatic surface tester (KES FB4-AUTO-A manufactured by Kato Tech Co., Ltd.), a probe using a steel piano wire with a diameter of 0.5 mm is used to measure the friction force when the probe is moved back and forth over a length of 30 mm with a probe area of 1 cm ² , a load of 50 gf/cm ² , and a speed of 1 mm/s. The analysis distance is set to 20 mm by cutting data from both ends. The surface friction coefficient is determined as MIU, and the mean deviation of the surface friction coefficient is determined as MMD. The measurement surface is such that the probe faces the surface, and the measurement directions are the X and Y directions, and the measured values are averaged. The initial sample tension is 10 gf/cm. Each measurement value is calculated by measuring five points on the sheet and averaging the results.

[Roughness characteristics]
The nonwoven fabric 10 has a moderate surface roughness at the peaks 11 of the convex portions 14 on the front side 10A, which allows the user to feel the unevenness when touched by hand, thereby providing a soft feel to the fibers of the nonwoven fabric. From this perspective, the surface roughness mean deviation (SMD) is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more. Furthermore, the smaller the surface roughness, the more gentle the contact with the skin can be maintained. From this perspective, the surface roughness mean deviation (SMD) is preferably 4 μm or less, more preferably 3.5 μm or less, and even more preferably 3.0 μm or less.

(Method of measuring roughness characteristics)
The surface roughness mean deviation (SMD) can be measured by the following method. That is, using the above-mentioned automatic surface testing machine, a 5 mm wide probe made of a single steel piano wire with a diameter of 0.5 mm is used to measure the roughness when it is moved back and forth over a length of 30 mm under conditions of a load of 10 gf/cm ² and a speed of 1 mm/s. As with the friction characteristics, the mean deviation of surface roughness within the analysis distance is determined as SMD. The measurement surface is such that the probe faces the surface, and the measurement directions are the X and Y directions, and the measured values are averaged. The initial sample tension is 10 gf/cm. Each measurement value is the average of measurements taken at five points on the sheet.

[Compression characteristics]
The greater the linearity (LC) of the compression characteristics of the protrusions 4, the more likely the nonwoven fabric 10 is to retain its thickness when pressed, and the more resilience it has when returned to its original shape when pressed with the skin of the hand, i.e., the more cushioning it feels. From this perspective, the linearity (LC) of the compression characteristics of the protrusions 4 is preferably 0.4 or more, and more preferably 0.5 or more. Furthermore, because people tend to feel that something is better when it initially deforms with a soft force and the resilience increases as the amount of compression increases, the linearity (LC) of the compression characteristics of the protrusions 4 is preferably 0.8 or less, and more preferably 0.7 or less.

When the compression energy (WC) of the protrusions 4 is neither too high nor too low, the nonwoven fabric 10 has an appropriate resistance to deformation when pressed by hand, resulting in a soft and fluffy texture. From this viewpoint, the compression energy (WC) of the protrusions 4 is preferably 3 gfcm/ ^cm2 or more, and more preferably 4.5 gfcm/ ^cm2 or more. Furthermore, from the viewpoint of suppressing repulsion force and maintaining an appropriate texture, the compression energy (WC) of the protrusions 4 is preferably 10 gfcm/ ^cm2 or less, and more preferably 8 gfcm/ ^cm2 or less.

Furthermore, if the recovery energy (WC') of the protrusions 4 of the nonwoven fabric 10 is large, the rebound properties when the fabric returns to its original shape when pressed with the skin of the hand, i.e., cushioning properties, become appropriate, resulting in an excellent texture. From this viewpoint, the recovery energy (WC') of the protrusions 4 is preferably 1.7 gfcm/ ^cm2 or more, and more preferably 2 gfcm/cm2 or ^more . Moreover, from the viewpoint of suppressing the resilience and maintaining an appropriate texture, the recovery energy (WC') of the protrusions 1 is preferably 10 gfcm/ ^cm2 or less, and more preferably 8 gfcm/ ^cm2 or less.

Then, the compression resilience RC (WC'/WC x 100) is calculated from the compression energy (WC) and the recovery energy (WC').
When the nonwoven fabric 10 has a large deformation amount, the larger the RC value, the smaller the hysteresis in the elastic stress between compression and recovery, the better the cushioning and the appropriate elasticity it feels. In other words, the nonwoven fabric 10 feels like it experiences less plastic deformation (sagging) when compressed. From this perspective, the RC value is preferably 42% or more, and more preferably 44% or more. Furthermore, the closer the RC value is to 100%, the better the elasticity. From this perspective, the RC value is preferably 100% or less, and more preferably 100%.

Furthermore, since the total thickness (T0) of the nonwoven fabric 10 in the initial state before pressing (under a load of 0.5 gf/ ^cm2 ) is within the above-mentioned range, it is possible to increase the amount of deformation when pressed, and the nonwoven fabric 10 can feel softer.

When the total thickness (TM) of the nonwoven fabric 10 under high load (under a pressure of 50 gf/ ^cm2 ) is within the above-mentioned range, it is less likely to collapse even under high load, and it can be felt that there is less plastic deformation (sagging).

The greater the thickness deformation (T0-TM), the softer the feel of the nonwoven fabric 10. From this perspective, the thickness deformation (T0-TM) is preferably 0.5 mm or more, more preferably 2.5 mm or more, and even more preferably 3.5 mm or more. There is no particular upper limit to the thickness deformation (T0-TM), but when the basis weight is 100 g/m2 or ^less , a smaller deformation prevents the distance between fibers from becoming too wide, and from the viewpoint of achieving excellent cushioning and strength, a smaller deformation is preferably 10 mm or less, more preferably 7 mm or less, and even more preferably 5 mm or less. The greater the deformation when a load is applied, the softer the feel.

(Method for measuring compression characteristics)
These compression properties can be measured by the following method. That is, using the above-mentioned automatic compression tester, a sheet is compressed with a measuring probe at a speed of 0.05 mm/s, with a measuring probe area of ² cm2, and within a compression load range of 0.5 gf/ ^cm2 to 50 gf/cm2. After applying the maximum load, the sheet is immediately moved in the recovery direction to measure the thickness and the load at that time. The thickness of the nonwoven fabric under ^a load of 0.5 gf/ ^cm2 is defined as TO, and the thickness of the nonwoven fabric under a load of 50 gf/ ^cm2 is defined as TM. The linearity of the compression properties is determined as LC, the compression energy as WC, the recovery energy as WC', the compression resilience as RC (WC'/WC x 100), and the deformation amount as "TO - TM." The measurement surface is such that the surface side faces the measuring probe. Each measurement value is calculated by measuring five points on the sheet and averaging the results.

[Preparing the measurement sample]
When preparing the nonwoven fabric 10 (sample) from the absorbent article for each of the above-mentioned measurements, if the nonwoven fabric 10 (sample) is adhered with a hot melt adhesive, the nonwoven fabric 10 (sample) is peeled off from the absorbent article using a cold spray or the like, in a manner that minimizes damage to the nonwoven fabric 10 (sample). Unless otherwise specified for each measurement, measurements are taken at randomly selected locations.

Next, we will explain a preferred embodiment of the nonwoven fabric manufacturing method of the present invention.

In the method for producing a nonwoven fabric of the present invention, various terms are defined as follows.
The "support" has a concave-convex shape, can engage with a pushing member, and temporarily holds the nonwoven fabric or unfused web. The convex and concave portions mentioned above refer to portions that have a relative height difference relative to the substrate. For example, a portion that protrudes higher than the substrate constituting the support is a convex portion. In this case, the portion of the substrate sandwiched between the convex portions can also be considered a concave portion. Furthermore, if the substrate constituting the support has a partially recessed portion, that portion becomes a concave portion. In this case, the portion of the substrate sandwiched between the concave portions can also be considered a convex portion. The support may be flexible, such as in the form of a conveyor or net, or non-flexible, such as in the form of a drum roll or plate. Various materials can be used for the support. Examples include resin, metal, carbon, and ceramic. A non-flexible embossing roll is preferred because it allows embossing heat fusion or embossing pressure bonding on the support.
The "pressing member" is a member having a concave-convex shape and capable of being pressed into (engaged with) the support. The pressing member may be flexible or inflexible, and examples thereof include a ring roll, a concave-convex roll, a net, a belt, a chain, a leaf spring (elastic plate-like body), and a movable load plate. Various materials can be used for the pressing member, and examples thereof include resin, metal, carbon, and ceramic.

"Interlocking" means that the concave portion of the support and the pushing portion of the pushing member are aligned, with the pushing portion fitting into the concave portion while leaving a gap large enough for the web to fit between the convex portion of the support and the pushing portion of the pushing member. In other words, the concave and convex shapes of the support and the pushing member are aligned so as to interlock. At this time, it is preferable that the support and the pushing member do not come into direct contact with each other, in order to reduce wear and deformation of the support and the pushing member.

The term "web" refers to a sheet-like fiber assembly including nonwoven fabrics and unfused webs. This web preferably contains thermoplastic fibers as constituent fibers.
The term "nonwoven fabric" refers to a sheet formed by forming a fiber assembly by thermal fusion, mechanical entanglement, or chemical bonding (adhesive, chemical bond, etc.). The nonwoven fabric of the present invention refers to a fabric having the above-mentioned interlayer fiber intersection fusion-bonded portions in its internal fiber structure.
The term "unfused web" refers to an aggregate of unfused fibers that can be fused by heat (hot air, steam, thermal embossing, ultrasonic embossing, etc.), and excludes nonwoven fabrics that have been mechanically entangled by methods such as hydroentanglement or needle punching before the fusion treatment step. More specifically, an unfused web is one that does not have the strength of a nonwoven fabric and has a maximum tensile strength of 100 cN/50 mm or less in the MD and CD directions. For example, this includes carded webs.

A "heat-fused" state means that the unfused web melts, causing the constituent fibers of the web in the heat-fused portion to lose their pre-fusion fibrous form. Having a fibrous form means that the ratio (former/latter) of the fiber length to the diameter (calculated as a perfect circle) calculated from the fiber's cross-sectional area is 300 times or more. For example, in a "heat-fused" state, at least a portion of the outer surface of the constituent fibers of the web melts, making the boundaries with the outer surfaces of other fibers indistinguishable, and the fiber form before the fusion process is lost. When the constituent fibers, such as composite fibers, are made of two or more resins, even if a specific resin does not melt and maintains its fibrous form, the other resins melt, making the boundaries between the outer surfaces of the constituent fibers indistinguishable, and the fiber form before the fusion process is lost. This can be confirmed by observing the cross section of the fused fiber portion using a scanning electron microscope (SEM).

"Embossed fusion" means that fibers are thermally fused together by external pressure and heat using an embossed or other uneven member. More specifically, it means that the resin of at least one fiber at the bonding interface between the fibers is melted by pressure and heat (due to intermolecular friction, self-heating due to compression, or external heating) and bonded to the other fiber.
"Embossed pressure bonding" means that fibers are pressure-bonded to each other by external pressure or heat using an embossing or other uneven member. More specifically, it means that one fiber adheres to another fiber without the resin being melted by heat or pressure.

The fibrous material constituting the web may be any ordinary fiber or heat-stretched fiber. From the viewpoint of fluffing and strength, the fibrous material is preferably continuous fiber, but is not limited thereto and may be long fiber or short fiber.
The continuous fibers are essentially continuous fibers, except for broken fibers at the end faces of the product member and broken fibers in some of the fuzzed portions, and are found in the spunbond method.
The long fibers have an effective fiber length (80 mm or more) and are found in the meltblown method.
Short fibers are fibers having a length of 77 mm or less, and are used in air-through nonwoven fabrics, spunlace nonwoven fabrics, and air-laid nonwoven fabrics.

Methods for supplying unfused webs include the spunbond method (before embossing, continuous fibers), electrospinning method (continuous fibers), spunmelt method (a method that combines hot air stretching and cold air stretching, long fibers), meltblown method (long fibers), carded method (short fibers), and airlaid method (short fibers). The spunbond and carded methods are particularly preferred, as they produce bulky, three-dimensionally shaped nonwoven fabrics. It is also possible to combine these supply methods.

The fiber material preferably contains thermoplastic fibers, such as polyolefin fibers, such as polyethylene (PE) fibers and polypropylene (PP) fibers, and fibers made solely from thermoplastic resins, such as polyethylene terephthalate (PET) and polyamide. Also, composite fibers with structures such as sheath-core and side-by-side can also be used. The use of composite fibers is preferred in the present invention. Examples of composite fibers include sheath-core fibers, in which a high-melting-point component is in the core and a low-melting-point component is in the sheath, and side-by-side fibers, in which the high-melting-point and low-melting-point components are arranged side by side. Preferred examples of such composite fibers include fibers with a sheath-core structure in which the sheath component is polyethylene or low-melting-point polypropylene. Representative examples of such sheath-core fibers include fibers with a PET (core) and PE (sheath), PP (core) and PE (sheath), and PP (core) and low-melting-point PP (sheath). More specifically, the constituent fibers preferably include polyolefin fibers, such as polyethylene fibers and polypropylene fibers, polyethylene composite fibers, and polypropylene composite fibers. Here, the composite composition of the polyethylene composite fiber is preferably polyethylene terephthalate and polyethylene, and the composite composition of the polypropylene composite fiber is preferably polyethylene terephthalate and low-melting-point polypropylene, more specifically, PET (core) and PE (sheath), or PET (core) and low-melting-point PP (sheath). Unless otherwise specified, the melting points of the resins used refer to those measured under atmospheric pressure (in a _N2 gas atmosphere).

These fibers can be used alone or in combination to form a web. The web may also contain fibers other than thermoplastic fibers, such as natural fibers like cotton and pulp, and recycled fibers like rayon and cupra. Therefore, it is preferable that the nonwoven fabric produced by the manufacturing method of the present invention contain the above-mentioned fibers.

The method for producing a nonwoven fabric of the present invention includes the following steps (hereinafter also referred to as step (I), step (II), and step (III)).
(I) A first shaping step in which a first unfused web consisting of an aggregate containing fibers is shaped by engaging a support having a convex or concave portion with a first pushing member having a pushing portion that can engage with the support.
(II) A second shaping step in which a second unfused web is laminated on the shaped first unfused web on the support, and the second unfused web is shaped from the second unfused web side by engaging with a second pushing member having a pushing portion that can engage with the support.
(III) A heat treatment step in the second shaping step or after the second shaping step, in which fibers are fused with a heated fluid, or embossed and pressed or embossed and fused.

In the two-stage intermeshing shaping process of steps (I) and (II) described above, the ratio (former/latter) of the amount of intermeshing of the first pushing member with the support to the amount of intermeshing of the second pushing member with the support is 1.2 or greater. In other words, the amount of intermeshing of the first unfused web is greater than the amount of intermeshing of the second unfused web by 1.2 or more. The first unfused web becomes the first fiber layer in the nonwoven fabric of the present invention, and the second unfused web becomes the second fiber layer.

This two-stage meshing shaping process is, for example, a shaping process as shown in FIGS. 6(A) and 6(B).
6(A) shows the first shaping step of step (I). In this step, a first unfused web 100, which will become the first fiber layer 1, is supported on the convex portions 111 of a support 110, and the pushing portion 121 of a first pushing member 120A pushes the first unfused web 100, which is located in the concave portions 112 between the convex portions 111, with an engagement amount K1. This causes the pushed portion of the first unfused web 100 to be stretched and shaped into a convex shape toward the support. After the first pushing member 120A is peeled off the first unfused web 100, the shaped first unfused web 100 is held on the support 110. Methods for holding the support 110 include suction from the back side where the convex portion 111 is not present, increasing the surface roughness of the side surface of the convex portion 111 of the support 110, and decreasing the surface roughness of the side surface of the pressing portion 121 of the pressing member 120A. In Fig. 6(A) , the support 110 is positioned on the upper side, but the support 110 may be positioned on the lower side and the first pressing member 120A may be positioned on the upper side.
6(B) shows the second shaping step of step (II). In this step, a second unfused web 200, which will become the second fiber layer 2, is laminated on the shaped first unfused web 100. Next, the pressing portion 122 of the second pressing member 120B presses, from the side of the second unfused web 200, the laminate of the first unfused web 100 and the second unfused web 200 in the recessed portion 112 between the protruding portions 111, 111 of the support 110 with an engagement amount K2. This causes the pressed portion of the second unfused web 200 to be stretched and shaped into a convex shape toward the support. The second unfused web 200 is shaped based on the aforementioned engagement ratio. At this time, depending on the meshing amount K1, the meshing amount K2, and the thickness of the second unfused web 200, the top of the first unfused web 100 may be pressed into contact with the second unfused web 200, or may be shaped with a gap between them. In the former case, by setting the ratio (K1/K2) to the meshing amount to 1.2 or more, the top of the first unfused web 100 will not be pressed in excessively strongly by the second unfused web 200. As a result, the thickness of the first unfused web 100 is maintained without excessive shaping.

In steps (I) and (II), as shown in Figures 6(A) and (B), the first unfused web 100 and the second unfused web 200 are directly pressed into the fabric using mechanical pressure. This causes the unfused webs 100 and 200 to be shaped into irregularities that conform to the shape of the support 110. This results in a nonwoven fabric with stronger fiber orientation and a higher proportion of components oriented perpendicular to the plane of the nonwoven fabric, compared to when the webs are pressed into the fabric using nonmechanical pressure, such as wind. Furthermore, a large pressing force is not required to create a large difference in the height of the irregularities formed in the unfused webs 100 and 200, allowing the fiber webs to be shaped softly. Furthermore, fiber disorder can be suppressed, improving formability. By appropriately setting the pressing depth in steps (I) and (II), the wall fiber orientation degree and wall fiber orientation angle possessed by the nonwoven fabric of the present invention can be achieved. It is preferable that the recess 112 of the support 110 has an opening 113 for passing the heated fluid in step (III). Although a two-stage interlocking shaping process is shown in Figure 6, a three-stage interlocking shaping process may also be performed. In this case, the number of layers may be two, or the number of layers may be equal to the number of interlocking shaping processes.

As shown in FIG. 7 , the first unfused web 100 has a larger intermeshing amount (K1/K2≧1.2) than the second unfused web 200, resulting in a higher draw ratio and correspondingly larger wall fiber orientation and wall fiber orientation angle. Furthermore, due to the difference in intermeshing amount (K1/K2≧1.2), the draw ratio at the wall of the first unfused web 100 is higher than that of the second unfused web 200, resulting in shaping at different draw ratios. Therefore, the return amount B2 of the fiber structure of the second unfused web 200 after shaping is greater than the return amount B1 of the fiber structure of the first unfused web 100 after shaping (B1<B2). This makes it easier for the fiber structure of the second unfused web 200 to return to its original state after shaping, further reducing the wall fiber orientation and wall fiber orientation angle of the second unfused web 200.

After steps (I) and (II), in step (III), a heat treatment step, the laminate of the shaped first unfused web 100 and the second unfused web 200 is subjected to heat treatment on a support 110, thereby forming fiber intersection fusion P and producing the nonwoven fabric of the present invention.
The heat treatment step (III) may be performed not only once but also multiple times. For example, fiber fusion using a heated fluid may be performed multiple times, or the fiber thermal fusion using a heated fluid may be performed in combination with embossing or embossing.

The nonwoven fabric of the present invention can be suitably produced by the method for producing the nonwoven fabric of the present invention, which includes the above steps (I) to (III).
Specifically, the fiber orientation of the two unfused webs 100 and 200 can be suitably controlled. This control allows the nonwoven fabric of the present invention to be suitably formed with the aforementioned specific wall fiber orientation degree, specific wall fiber orientation angle, and various area ratios, including appropriate voids. In addition, by performing intermeshing shaping in two or more stages with different intermeshing amounts, the spacing between fibers in the unfused web can be increased, maintaining a large area filled with fibers, and forming a bulky structure. In this regard, the more the unfused webs 100 and 200 are stretched by intermeshing shaping, the greater the fiber orientation, but the longer the interfiber distance, the lower the fiber density, and the lower the fiber bulk density. Based on this, by controlling the intermeshing amount in two stages, suitable fiber orientation and bulk density (bulkiness) can be simultaneously achieved.
As a result, the nonwoven fabric of the present invention can be suitably produced, which has a bulky and thick fiber structure while being soft and having good cushioning properties, and which can maintain its thickness when used under pressure and is resistant to crushing.

In particular, by setting the meshing ratio to 1.2 or more, the nonwoven fabric of the present invention produced can be made to have high total thickness (TM) retention under high load (50 gf/ ^cm2 ) and to be resistant to crushing without deteriorating the texture. The reason for this is that by pressing in two stages at the above ratio, the thickness of the unfused web of each layer can be maintained in a thick state.
In the conventional case where two layers are stacked and pressed simultaneously, the first unfused web is pressed through the second unfused web, resulting in a shape compressed in the thickness direction. Furthermore, when two layers are simultaneously shaped in a single-stage intermeshing shaping process, shaping is performed without the formation of voids. In this case, the wall fiber orientation degree and wall fiber orientation angle of each layer are approximately the same, and the resulting nonwoven fabric tends to require high compression energy when pressed and to be hard to the touch.
In contrast, in the method for producing the nonwoven fabric of the present invention, by performing an interlocking shaping process in which the fibers are pressed in two stages at the above ratio, the shaping of the first fiber layer 1 and the second fiber layer 2 can be controlled independently, and the nonwoven fabric of the present invention can be preferably produced.

In this way, by setting the meshing ratio as described above, it is possible to impart the specific degree of fiber orientation as described above, and also to favorably maintain the overall thickness of the first unfused web during shaping.
From the above viewpoint, the meshing ratio is preferably 1.2 or more, and more preferably 1.5 or more. From the same viewpoint, the meshing ratio is preferably 5.0 or less, and more preferably 3.0 or less.

The amount of meshing may be appropriately set within the above range depending on the basis weight and thickness of the unfused web.
The basis weight and thickness of the unfused web are within the ranges normally used for this type of article and can be appropriately set depending on the purpose of the nonwoven fabric to be manufactured. For example, the basis weight may be within the range shown for the nonwoven fabric 10. Furthermore, it is practical to set the thickness of the unfused web in the intermeshed state for each layer to, for example, 1 mm or less.

The method for producing a nonwoven fabric of the present invention is not limited to laminating only two types of unfused webs 100 and 200. For example, a step of laminating another unfused web or nonwoven fabric after step (II) may be included. In this case, the heat treatment step (III) described above will be carried out after this. This provides the nonwoven fabric of the present invention with a flat lower layer, which prevents the nonwoven fabric from stretching in the width direction and crushing of convex portions when rolled up.

In the method for producing a nonwoven fabric of the present invention, it is preferable that the area of the top of the pushing portion 122 of the second pushing member 120B is larger than the area of the pushing portion 121 of the first pushing member 120A used in steps (I) and (II). For example, as shown in Figure 7, it is preferable that the area of the top of the pushing portion 122 of the second pushing member 120B is larger than the area of the top of the pushing portion 121 of the first pushing member 120A.
In this case, after shaping, the radius of curvature of the region of the second unfused web 200 pressed by the pressing section 122 is larger than the radius of curvature of the region of the first unfused web 100 pressed by the pressing section 121. Therefore, even after the pressing section 122 is peeled off, the shaped shape of the second unfused web 200 tends to be stable along the radius of curvature. Furthermore, the contact interface between the first unfused web 100 and the second unfused web 200 at the wall portion tends to be increased, and more interlayer fiber intersection fused portions P can be formed. In addition, because the area of the top of the pressing section 121 that presses the first unfused web 100 is limited to be smaller than the area of the top of the pressing section 122 that presses the second unfused web 200, the area of the first unfused web 100 that is not directly pressed by the pressing section 121 relatively increases. This makes the first unfused web 100 and the first fiber layer 1 relatively bulkier and thicker.

From the above viewpoint, the ratio (former/latter) of the area of the top of the pushing portion 122 of the second pushing member 120B to the area of the top of the pushing portion 121 of the first pushing member 120A is preferably 1.0 or more, more preferably 1.2 or more, and even more preferably 1.4 or more.
Furthermore, the ratio (former/latter) of the area of the top of the pushing portion 122 of the second pushing member 120B to the area of the top of the pushing portion 121 of the first pushing member 120A is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less, in order to ensure a sufficient gap between the support 110 and the top of the pushing portion 122 of the second pushing member 120B (to prevent contact or interference between the support and the pushing member).

Furthermore, in the nonwoven fabric manufacturing method of the present invention, in the planar direction of the laminate of the first unfused web 100 and the second unfused web 200, there may be an area where the pushing position of the pushing portion 121 of the first pushing member and the pushing position of the pushing portion 122 of the second pushing member do not overlap.
For example, in Fig. 8(A), on a plane where square convex portions 111 of a support are arranged in a grid pattern at equal intervals, the pushing portion 121 of the first pushing member is pushed into three locations into multiple concave portions running parallel between multiple rows of convex portions 111 arranged in one direction. In contrast, in Fig. 8(B), the pushing portion 122 of the second pushing member is pushed into one of these locations. As a result, as shown in Fig. 9, the shaping patterns of the first unfused web 100 and the second unfused web 200 are different, and the voids 3 formed between the first unfused web 100 and the second unfused web 200 can be made larger in some locations, creating softness. However, in this case, it is preferable that the area where the pushing positions of the pushing portion 121 of the first pushing member and the pushing position of the pushing portion 122 of the second pushing member overlap is 50% or more of the pushing area. In Figures 8(A) and (B), the intervening first unfused web 100 and second unfused web 200 are omitted to facilitate understanding of the relationship between the pushing portion 121 of the first pushing member and the pushing portion 122 of the second pushing member in the planar direction of the support body.

Next, specific examples (Specific Example 1 and Specific Example 2) of preferred manufacturing equipment for use in the above-mentioned method for manufacturing the nonwoven fabric of the present invention will be described with reference to the drawings.

10 shows a nonwoven fabric manufacturing apparatus 900 using a drum-shaped support 110 with an uneven peripheral surface as a support for two-stage meshing shaping. A first pushing member 120A and a second pushing member 120B are disposed on the peripheral surface of the support 110 so as to be capable of meshing with each other. The first pushing member 120A and the second pushing member 120B are roll-shaped.
First, the first unfused web 100 is fed between the support 110 and the first pushing member 120A, and the support 110 and the first pushing member 120A engage with each other to carry out the above-mentioned step (I).
Next, the second unfused web 200 is fed onto the uneven first unfused web 100 that is laid along the peripheral surface of the support 110, and the aforementioned step (II) is carried out by engaging the support 110 with the second pushing member 120B.

The convex or concave portions of the support 110 preferably extend in the machine flow direction (the direction of rotation of the drum shape). Furthermore, it is preferable that the convex or concave portions also extend in the width direction (the direction of the rotation axis of the drum shape), which is perpendicular to the machine flow direction. Furthermore, it is preferable that the support 110 applies negative pressure from the circumferential surface to the inside. This allows the first unfused web 100 and the second unfused web 200, which are laid along the circumferential surface of the support 110, to be sucked in, maintaining the laid-in state better before proceeding to the next process.

Next, while the unevenly textured laminate of the first unfused web 100 and second unfused web 200 is held on the peripheral surface of the support 110, hot air W1 is blown onto it at the hot air blowing section 140 to fuse the fibers using the heated fluid in the aforementioned step (III). This produces the nonwoven fabric 10 according to the present invention.

When blowing the hot air W1, it is preferable to hold down the entire laminate from the second unfused web 200 side with a net 130. This prevents fibers from scattering when the hot air W1 is blown. It is also preferable to have a hot air suction section 141 inside the drum of the support 110, at a position opposite the hot air blowing section 140.

The temperature of the hot air W1 is preferably 140° C. or higher, more preferably 145° C. or higher, and even more preferably 150° C. or higher, from the viewpoint of thermally fusing the thermoplastic fibers and stabilizing the shape of the nonwoven fabric. Moreover, the temperature of the hot air W1 is preferably 180° C. or lower, more preferably 175° C. or lower, and even more preferably 170° C. or lower, from the viewpoint of preventing excessive thermal fusion of the thermoplastic fibers and improving the softness of the nonwoven fabric.
In addition, the wind speed of the hot air W1 is preferably 15 m/sec or less, more preferably 12 m/sec or less, and even more preferably 10 m/sec or less, from the viewpoint of improving cushioning properties and enhancing the retention of the overall thickness of the nonwoven fabric 10. Furthermore, the wind speed of the hot air W1 is preferably 2 m/sec or more, more preferably 3 m/sec or more, and even more preferably 4 m/sec or more, from the viewpoint of thermally fusing the thermoplastic fibers and stabilizing the shape of the nonwoven fabric.

Furthermore, in the nonwoven fabric manufacturing apparatus 900 of Example 1, it is preferable to arrange a cooling section 150 having a cooling nozzle and a cooling suction section 151 inside the drum of the support 110 opposite each other at a position where the nonwoven fabric 10 obtained by blowing the hot air W1 is laid along the outer periphery of the drum of the support 110. As a result, as described above, the support 1 can be kept below a certain temperature, and the obtained nonwoven fabric can be peeled off while maintaining its shape, thereby maintaining good cushioning properties.

The above steps (I), (II), and (III) can be carried out under various conditions, etc. For example, the various conditions described in paragraphs [0010] to [0067] of the specification of JP-A-2019-112747 can be appropriately adopted.
Various configurations of the support 110 and the pressing members 120A and 120B used in steps (I) and (II) can be used. For example, the support shown in FIG. 2 in the above-mentioned document and the pressing members shown in FIGS. 3, 7, and 8 in the above-mentioned document can be used. The support shown in FIG. 2 is a drum-type support having convex portions, concave portions, and apertures on its circumferential surface. A plurality of convex portions are arranged on the circumferential surface of the support, spaced apart from each other in the rotational direction and the rotational axis direction. As a result, the concave portions extend at least in the rotational direction of the support. Furthermore, the concave portions also extend in the rotational axis direction. The pressing member shown in FIG. 3 has pressing portions that are inserted into the drum-type circumferential surface along the concave portions of the support. As a result, the pressing portions are arranged in a lattice pattern. The pressing portions are hollow, forming grid-like spaces. The pressing member shown in FIG. 8 is a belt-like member made by weaving string-like pressing portions into a lattice pattern. The pushing member shown in FIG. 9 is drum-shaped and is made up of a plurality of rings arranged in the direction of the rotation axis, with the rings forming a pushing portion that extends in the direction of rotation.

Furthermore, the nonwoven fabric manufacturing apparatus 900 of Example 1 may have a mechanism for laminating another unfused web or nonwoven fabric (web 300) after peeling the nonwoven fabric 10 from the peripheral surface of the support 110. In this case, it is preferable to have another mechanism for performing the above-mentioned step (III) after this.

The nonwoven fabric manufacturing apparatus 910 of Example 2 shown in Figure 11 includes a web supply section 102 that supplies an unfused web 100, a conveyor belt 104 that transports the unfused web 100 supplied from the web supply section 102, and a nip roller 106 that applies pressure to the first unfused web 100 transported by the conveyor belt 104. Downstream of these are a pair of rolls (support 110 and first pushing member 120A) that interlock and perform uneven shaping processing on the first unfused web 100, and a roll (second pushing member 120B) that merges the second unfused web 200 with the uneven first unfused web 100 on the peripheral surface of the support 110 and performs uneven shaping processing on the second unfused web 200. Further downstream, there is a point bonding means 130 that bonds some or all of the fibers at the bottom of the recesses in the laminate of the uneven first unfused web 100 and second unfused web 200 pulled by the support 110, and a cooling roll 114 that cools the fused areas (embossed areas) bonded by the point bonding means 130. Furthermore, downstream of the cooling roll 114, there is a heat flow section 118 that sprays heated fluid to bond the fiber intersections, i.e., to form a nonwoven fabric.

The web supply unit 102, conveyor belt 104, and nip roller 106 are configured to supply and transport the first unfused web 100 toward the support 110 and first pushing member 120A. The cooling roll 114 is configured to cool and transport the laminate of the first unfused web 100 and the second unfused web 200, on which the embossed portions 6 have been formed by the point joining means 130, downstream. While the conveyor belt 104, nip roller 106, and cooling roll 114 may not be used as needed, their inclusion is preferable for stable production. The web supply unit 102, conveyor belt 104, nip roller 106, and cooling roll 114 can employ a variety of commonly used configurations.

In the manufacturing apparatus 910 having the above configuration, the unfused web 100 is first supplied from the web supply unit 102 onto the conveyor belt 104. The unfused web 100 is then conveyed between the support 110 and the first pushing member 120A by the conveyor belt 104 while being pressed by the nip rollers 106. Here, the nip rollers 106 do not firmly bond the fibers together, but rather press the fibers together to a degree that allows the unfused web 100 to be conveyed. Most of the pressed portions tend to peel off due to the tensile force generated when the support 110 and the first pushing member 120A engage. This reduction in the number of pressed portions due to peeling is preferable because it increases the degree of freedom of the fibers and results in excellent texture. Furthermore, even if some of the pressed portions remain, these pressed portions are not fused portions, and therefore hardly cause any deterioration in texture due to snagging.

Furthermore, in the nonwoven fabric manufacturing apparatus 910 of Example 2, the web supply unit 102 is shown as supplying a single-layer unfused web 100, but this is not limited to this. For example, the web supply unit 102 may include two or more devices so as to be able to supply an unfused web 100 with a thickness of two or more layers. When the first unfused web 100 is supplied onto the conveyor belt 104 as a laminate of two or more layers, in the manufacturing apparatus 910, the support 110 and first pushing member 120A impart unevenness to the entire laminate.

In the nonwoven fabric manufacturing apparatus 910 of Example 2, the above-described steps (I) and (II) are carried out by engagement between the support 110 and the first pushing member 120A and the second pushing member 120B, as in the nonwoven fabric manufacturing apparatus 900 of Example 1. This results in a laminate of the unevenly textured first unfused web 100 and second unfused web 200.
The unevenly textured laminate of the first unfused web 100 and the second unfused web 200 is brought into close contact with the peripheral surface of the support 110 by frictional force, suction, or the like, and is then transported to the position of the point bonding means 130 by the rotation of the support 110 while maintaining the uneven shape. The fibers at the bottom of the recesses in the laminate are embossed or fused by the clamping between the point bonding means 130 and the protruding or recessed portions of the support 110. This forms the embossed portions 6 in a predetermined pattern. The laminate is then transferred to the cooling roll 114 and cooled, and is transported downstream on the second conveyor belt 117, where the fiber intersections are fused at the heat flow portion 118 (step (III)).
This makes it possible to suitably produce the nonwoven fabric of the present invention, which has a bulky and thick fiber structure that is soft and has good cushioning properties, and which can maintain its thickness when used under pressure and is resistant to crushing.

Furthermore, the nonwoven fabric manufacturing apparatus 910 of Example 2 may have a mechanism for merging and laminating the unevenly textured laminate of the first unfused web 100 and second unfused web 200 with another unfused web or nonwoven fabric (web 300). In this case, the embossed portion is formed by the point joining means 130 while the laminate and web 300 are laminated together.

The nonwoven fabric of the present invention can be used for various purposes.
For example, the nonwoven fabric of the present invention can be used in absorbent articles such as diapers, sanitary napkins, panty liners, and urine absorption pads. Absorbent articles typically have a liquid-permeable top sheet, a back sheet, and an absorbent body sandwiched between them. The nonwoven fabric of the present invention is particularly suitable for use as a top sheet. Further, the nonwoven fabric can also be used as a sheet in the gathered portion, an exterior sheet, or a sheet in the wing portion of an absorbent article.
The nonwoven fabric of the present invention can also be used as a sweat-absorbing sheet or as a component of an eye mask or mask.

The present invention will be explained in more detail below based on examples, but the present invention should not be construed as being limited thereto. In these examples, "parts" and "%" are all based on mass unless otherwise specified. In Table 1 below, "-" means that the item does not have a corresponding item or value, etc.

Example 1
As shown below, a first unfused web 100 and a second unfused web 200 were prepared.
Thermoplastic concentric composite staple fibers of a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) with a fineness of 1.1 dtex were used for the first unfused web 100. Thermoplastic concentric composite staple fibers of a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) with a fineness of 3.3 dtex were used for the second unfused web 200. Both fibers were coated with a hydrophilic oil agent.
A first unfused web 100 (basis weight 15 g/ ^m2 ) and a second unfused web 200 (basis weight 15 g/ ^m2 ) were formed using a carding machine. The first unfused web 100 was shaped by engaging the first pushing member and support as shown in Figure 6(A) to form a concave-convex shape. Thereafter, as shown in Figure 6(B), the second unfused web 200 was laminated on the previously shaped first unfused web 100, and the laminated web was shaped on the same support by engaging the second pushing member and support. The conditions were as shown in the table. The ratio (former/latter) of the area of the top of the pushing portion 122 of the second pushing member to the area of the top of the pushing portion 121 of the first pushing member was 1.0.
The interlocked laminate was placed on a support and hot air (temperature 160°C, air speed 4.3 m/s, air blowing time 1.5 seconds) was blown from the second unfused web side to perform a fiber intersection fusion treatment. The interlocked laminate was then peeled off from the support and then subjected to a hot air treatment on the backside (second fiber layer) side on a conveyor net at a hot air temperature of 136°C, air speed 1.5 m/s, and air blowing time 6 seconds to form fused fiber intersections. This produced a nonwoven fabric sample of Example 1.

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 meshing amounts of the first pushing member and the second pushing member were set as shown in Table 1.

Example 4
The second unfused web 200 was laminated on the shaped first unfused web 100, and the laminated webs were interlocked and shaped on the same support by the second pushing member and the support. A flat third unfused web 300 (basis weight 15 g/ ^m2 ) was then laminated on top of this. The third unfused web 300 was not interlocked and shaped, and hot air (temperature 160°C, wind speed 4.3 m/s, blowing time 1.5 seconds) was blown onto the third unfused web side of the laminate on the support to perform a fiber intersection fusion treatment. A nonwoven fabric sample of Example 4 was produced in the same manner as in Example 1, except for the above. The third unfused web 300 was made of thermoplastic concentric composite staple fibers with a core-sheath structure (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) having a fineness of 3.3 dtex.

(Comparative Example 1)
A nonwoven fabric sample of Comparative Example 1 was prepared in the same manner as in Example 1, except that the meshing amount between the first pushing member and the second pushing member was as shown in Table 1 and the meshing amount ratio was 1.1.

(Comparative Example 2)
A nonwoven fabric sample of Comparative Example 2 was prepared in the same manner as in Example 1, except that the second unfused web was not interlocked and shaped, but was laminated in a flat shape.

(Comparative Example 3)
The first unfused web and the second unfused web used in Example 1 were not subjected to mesh shaping, but instead were subjected to two-stage hot air shaping to produce a nonwoven fabric sample for Comparative Example 3. The two-stage hot air shaping was performed as follows. Specifically, the first unfused web 100 was placed on the support shown in FIG. 6(A), and hot air was blown from the web side at a temperature of 160°C, a wind speed of 6 m/s, and a blowing time of 0.2 seconds to perform hot air shaping and fiber intersection fusion treatment, resulting in a first fused web. The second unfused web 200 was then laminated on top of the first fused web. The laminate of the first fused web and the second unfused web 200 placed on the support was then subjected to hot air shaping and fiber intersection fusion treatment by blowing hot air from the second unfused web 200 side at a temperature of 160°C, a wind speed of 2 m/s, and a blowing time of 1.5 seconds. A nonwoven fabric sample of Comparative Example 3 was prepared in the same manner as in Example 1 except for the above.

The nonwoven fabric samples of each Example and Comparative Example were subjected to the following tests. The following tests (1) to (3) were performed based on the respective measurement methods described above.
(1) Wall fiber orientation degree, wall fiber orientation angle, and fiber density Measurements were made based on the above-mentioned (Method for measuring wall fiber orientation degree and wall fiber orientation angle) and (Method for measuring fiber density).
(2) Area ratio of the gaps 18, the first fiber layer 1, the voids 3, the second fiber layer 2, and the gaps 28: This was measured based on the above-mentioned (Method for measuring the void ratio).
(3) Frictional Properties, Roughness Properties, and Compression Properties Measurements were made based on the above-mentioned (Method for measuring frictional properties), (Method for measuring roughness properties), (Method for measuring compression properties), and (Method for measuring the total thickness of a nonwoven fabric under a load of 0.5 gf/ ^cm2 ).
(4) Texture Based on a sensory evaluation of a combination of factors such as cushioning, deformation when pressed by hand, and smoothness, the nonwoven fabric of Comparative Example 1 was given a score of 1, and the three-dimensionally shaped nonwoven fabric obtained by peeling the surface material from Kao Corporation's Merry's Tape-type diaper, size M (manufactured in Japan in 2019), was given a score of 3. The higher the score, the better the texture. Evaluation was performed on a 5-point scale, with three male and three female researchers performing the blind evaluation. The obtained values were rounded off to the nearest whole number.
In addition, the larger the deformation amount when pressed by hand, the softer it tends to feel. When the deformation amount is large, the greater the compression resilience (RC), the smaller the hysteresis in the elastic stress between compression and recovery, and the better the cushioning tends to feel. Furthermore, when the mean coefficient of friction (MIU) is in the above-mentioned appropriate range and the mean deviation value of the surface friction coefficient (MMD) is small, the smoothness tends to be felt as being moderate, and even if the surface is uneven, there is no catching, and the fluctuation of the friction coefficient is small, and the smoothness tends to be felt as being smooth.

The evaluation results are shown in Tables 1 and 2 below. The states of the fiber layers observed when measuring the "total thickness under a load of 0.5 gf/ ^cm2 " of the nonwoven fabric samples of Examples 1 to 4 were as shown in Figures 12(A) to 12(D). The states of the fibers of the fiber layers observed when measuring the "thickness under a load of 0.5 gf/ ^cm2 " of the nonwoven fabric samples of Comparative Examples 1 to 3 were as shown in Figures 12(E) to 12(G).

As shown in Tables 1 and 2, the nonwoven fabric samples of Examples 1 to 4 had a wall fiber orientation degree of the first fiber layer of 0.70 to 0.95, and a ratio of the wall fiber orientation degree of the first fiber layer to the wall fiber orientation degree of the second fiber layer of 1.1 to 1.5, and therefore had the thickness characteristics shown below.
That is, the nonwoven fabric samples of Examples 1 to 4 had higher WC' values (cushioning properties) indicated as compression properties than the nonwoven fabric samples of Comparative Examples 2 and 3, and their WC values (resistance to deformation) were neither too high nor too low compared to those of the nonwoven fabrics of Comparative Examples 1 to 3. The nonwoven fabric samples of Examples 1 to 4 also had sufficiently high RC values (elasticity). Therefore, the nonwoven fabric samples of Examples 1 to 4 were fluffy, soft, and had good cushioning properties compared to Comparative Examples 1 to 3.
Furthermore, the nonwoven fabric samples of Examples 1 to 4 had a "total thickness T0 under a load of 0.5 gf/ ^cm2 " (thickness in the initial state before pressing) that was thicker than the nonwoven fabric sample of Comparative Example 3. In addition, the nonwoven fabric samples of Examples 1 to 4 maintained a "total thickness TM under a load of 50 gf/ ^cm2 " (total thickness under high load) that was thicker than the nonwoven fabric samples of Comparative Examples 2 and 3. Therefore, the nonwoven fabric samples of Examples 1 to 4, while having the soft and good cushioning properties described above, were bulkier and thicker than the nonwoven fabric samples of Comparative Examples 1 to 3, and were able to maintain this thickness under pressure and were less likely to be crushed. Among them, the nonwoven fabric sample of Example 2 was thick and deformed significantly under low loads, and felt slightly softer than the nonwoven fabric sample of Example 1.

In addition, the nonwoven fabric samples of Examples 1 to 3 were soft at the beginning of compression, and then the second fiber layer 2 compensated for the first fiber layer 1's resistance to crushing, resulting in excellent feel (feel rating: 4 or 5). Among the nonwoven fabric samples of Examples 1 to 3, the nonwoven fabric sample of Example 1 had a high "wall fiber orientation angle of the first fiber layer minus the wall fiber orientation angle of the second fiber layer" in addition to the aforementioned sufficient "ratio of the wall fiber orientation degree of the first fiber layer to the wall fiber orientation degree of the second fiber layer." Therefore, the nonwoven fabric sample of Example 1 had a good balance of the area proportions of the gaps 18, the first fiber layer 1, the voids 3, the second fiber layer 2, and the gaps 28 in the cross section shown in Figure 5 , and had a higher "total thickness TM under a load of 50 gf/ ^cm² " compared to Examples 2 and 3, which had a higher "total thickness T0 under a load of 0.5 gf/ ^cm². " Therefore, the nonwoven fabric sample of Example 1 had the best feel among the nonwoven fabric samples of Examples 1 to 3 (feel rating: 5).
In contrast, the nonwoven fabric sample of Comparative Example 1 felt relatively hard because the difference in the degree of meshing between the two stages was small during the manufacturing process and the ratio of the wall fiber orientation degrees was too small. Furthermore, because no voids were formed, the WC value (resistance to deformation) was too high, and the sample felt somewhat harder than Example 1, resulting in a poor feel. The standard deviation MMD of the friction coefficient also had a relatively high value. When a nonwoven fabric has a hard, uneven shape, the convex portions of the nonwoven fabric have difficulty following the measuring probe, so this value tends to be high. Therefore, a high standard deviation MMD tends to indicate poor feel (feel evaluation 2).
Although the nonwoven fabric sample of Comparative Example 2 had a "total thickness under a load of 0.5 gf/ ^cm² ," it had excessive voids between the first and second fiber layers, and the lower second fiber layer was nearly flat, resulting in an excessively large ratio of wall fiber orientation degrees and prone to collapse without compensating for the collapse of the upper layer ("total thickness under a load of 50 gf/ ^cm² " was insufficient). Therefore, the nonwoven fabric sample of Comparative Example 2 was inferior to the nonwoven fabric samples of Examples 1 to 3 in all of the LC value (cushioning), WC value (resistance to deformation), and WC' value (cushioning). For these reasons, the nonwoven fabric sample of Comparative Example 2 had a poor feel (feeling evaluation 1).
The nonwoven fabric sample of Comparative Example 3 was shaped only by hot air blowing, which prevented it from being sufficiently stretched, resulting in a small amount of unevenness (the area ratio of the gaps 18 on the surface side 10A of the first fiber layer 1 was small), and the wall fiber orientation ratio was too low, resulting in a relatively stiff feel. Furthermore, due to the shaping, the "total thickness under a load of 0.5 gf/ ^cm2 " was relatively thin, resulting in a correspondingly small amount of deformation. For these reasons, the nonwoven fabric sample of Comparative Example 3 felt stiff and had a poor feel (feel evaluation 2).

As described above, the nonwoven fabrics of Examples 1 to 3 were soft and had good cushioning properties, while having a bulky and thick fiber structure that was able to maintain its thickness when used under pressure, was resistant to crushing, and also had an excellent texture.

1 First fiber layer 11 Top portion 12 Wall portion 13 Bottom portion 14 Convex portion 15 Concave portion 2 Second fiber layer 21 Top portion 22 Wall portion 23 Bottom portion 24 Convex portion 25 Concave portion 3 Void portion 4 Convex portion 5 Concave portion 6 Embossed portion 10 Nonwoven fabric T0 Total thickness of nonwoven fabric under no load T1 Total thickness of first fiber layer T2 Total thickness of second fiber layer D1 Actual thickness of first fiber layer D2 Actual thickness of second fiber layer M1 Mid-height position M2 of first fiber layer Mid-height position P of second fiber layer Interlayer fiber intersection fusion portion Q Intralayer fiber intersection fusion portion N Planar direction V Extension direction of fiber layer Z Thickness direction (direction of total thickness)
S: Direction of actual thickness E; Squares EA, EB; Side L1 of square; Intermediate positions 18, 28 in the direction of the actual thickness of each fiber layer; Gap 100: First unfused web 200; Second unfused web 110; Support 111: Convex portion 120A of support; First pushing member 121: Pushing portion 120B of first pushing member; Second pushing member 122: Pushing portion K1, K2 of second pushing member; Intermeshing amount B1, B2; Return amount 130; Net 140: Hot air blowing portion 141; Hot air suction portion 150; Cooling nozzle 151; Cooling suction portion 300; Web 900, 910; Manufacturing device W1; Hot air

Claims (10)

A nonwoven fabric in which two or more fiber layers are laminated in the thickness direction,
a first fiber layer on one surface side has convex portions and concave portions, and a second fiber layer adjacent to the first fiber layer on the other surface side in the thickness direction has convex portions extending into the convex portions of the first fiber layer on the other surface side,
at least an interlayer fiber intersection fusion-bonded portion is included at the interface between the wall portion of the convex portion of the first fiber layer and the wall portion of the convex portion of the second fiber layer,
a wall fiber orientation degree in the walls of the convex portions of the first fiber layer is 0.70 or more and 0.99 or less, and a ratio of the wall fiber orientation degree in the convex portions of the first fiber layer to the wall fiber orientation degree in the convex portions of the second fiber layer (the former/the latter) is 1.1 or more and 1.5 or less. The nonwoven fabric of claim 1, wherein the ratio of the fiber density at the top of the convex portions of the second fiber layer to the fiber density at the top of the convex portions of the first fiber layer (former/latter) is 0.8 or more and 1.8 or less. The nonwoven fabric according to claim 1 or 2, wherein the difference between the wall fiber orientation angle of the convex portions of the first fiber layer and the wall fiber orientation angle of the convex portions of the second fiber layer (the former - the latter) is 0 degrees or more and 50 degrees or less. a void is present between the first fiber layer and the second fiber layer,
The nonwoven fabric according to any one of claims 1 to 3, wherein the area ratio of the voids in a thickness direction cross section along the CD direction of the nonwoven fabric is 4% or more and 13% or less. The nonwoven fabric has a resistance of 50 gf/cm ² 5. The nonwoven fabric according to claim 4, having a total thickness under load of 0.5 mm or more. An absorbent article using the nonwoven fabric according to any one of claims 1 to 5 . a first shaping step of shaping a first unfused web made of an aggregate containing fibers by engaging a support having a convex portion or a concave portion with a first pushing member having a pushing portion that can be engaged with the support;
a second shaping step of laminating a second unfused web on the shaped first unfused web on the support, and shaping the second unfused web from the second unfused web side by engaging a second pushing member having a pushing portion capable of engaging with the support,
a ratio (former/latter) of an engagement amount of the first pushing member with the support to an engagement amount of the second pushing member with the support being 1.2 or more;
A method for producing a nonwoven fabric, comprising a step of fusing fibers with a heated fluid during or after the second shaping step. The method for producing a nonwoven fabric according to claim 7, wherein an embossing or embossing fusion step is carried out during or after the second shaping step, and then the fiber fusion step using the heated fluid is carried out. The method for producing a nonwoven fabric according to claim 7 or 8 , further comprising a step of laminating another unfused web or nonwoven fabric after the second shaping step. The method for producing a nonwoven fabric according to any one of claims 7 to 9 , wherein the pushing portion of the second pushing member has a larger top area than the pushing portion of the first pushing member.