Nonwoven

Abstract

To provide a nonwoven fabric that can maintain thickness so that it is hardly crushed while having soft and pleasant cushioning property.SOLUTION: A nonwoven fabric 10 has thermoplastic fibers, a fusion point between the fibers that is disposed at a fiber intersection, a first surface side 1A, and a second surface side 1B that is an opposite surface side to the first surface side. The nonwoven fabric has outer surface fiber layers on the first surface side and the second surface side in which fibers are oriented in a plane direction, and a plurality of connection portions 3 that are disposed between an outer surface fiber layer 1 on the first surface side and the outer surface fiber layer 2 on the second surface side and have fibers oriented in a thickness direction of the nonwoven fabric. The nonwoven fabric has an uneven structure in which convex portions 4 each consisting of the outer surface fiber layer on the first surface side and the connection portion and concave portions 5 each between the convex portions are alternately disposed on the first surface side. The outer surface fiber layer on the second surface side is a bottom of the concave portion. A fiber assembly layer 6 is disposed in the inside on the second surface side of the convex portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to nonwoven fabrics. [Background technology]

[0002] Nonwoven fabrics are often used in absorbent articles such as sanitary napkins and diapers. Techniques for imparting various functions to nonwoven fabrics are known.

[0003] Patent Documents 1 to 3 describe nonwoven fabrics having an uneven structure with a plurality of solid protrusions arranged on one side from the viewpoint of cushioning properties that allow easy recovery after compression. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-12913 A [Patent Document 2] JP 2006-115974 A [Patent Document 3] JP 2008-161526 A Summary of the Invention [Problem to be solved by the invention]

[0005] A nonwoven fabric having the above-mentioned uneven structure is excellent in terms of softness. On the other hand, nonwoven fabrics with a concave-convex structure are easily crushed when pressure is applied. In particular, when the nonwoven fabric is used as a top sheet of an absorbent article, the concave-convex structure is crushed when the wearer's body pressure is applied, and the distance between the wearer's skin and the absorbent body under the nonwoven fabric is reduced. This makes it easy for liquid to return, and there is room for improvement in terms of preventing liquid from remaining on the skin surface.

[0006] In view of the above, the present invention relates to a nonwoven fabric that is soft and has good cushioning properties, while being able to maintain its thickness and being resistant to crushing. [Means for solving the problem]

[0007] The present invention relates to a nonwoven fabric having thermoplastic fibers, fusion points between the fibers being arranged at fiber intersections, and having a first side and a second side which is the opposite side to the first side, the nonwoven fabric having outer surface fiber layers on the first side and the second side, in which the fibers are oriented in a planar direction, and a plurality of connecting portions disposed between the outer surface fiber layer on the first side and the outer surface fiber layer on the second side, the connecting portions being arranged in which the fibers are oriented in a thickness direction of the nonwoven fabric, the first side having an uneven structure in which convex portions formed of the outer surface fiber layer on the first side and the connecting portions and concave portions between the convex portions are alternately arranged, and the second side having a concave-convex structure in which the convex portions are formed of the outer surface fiber layer on the first side and the connecting portions and concave portions between the convex portions are alternately arranged, the outer surface fiber layer on the first surface side forms the bottom of the recess, a fiber assembly layer is disposed inside the second surface side of the protrusion, the apparent thickness of the nonwoven fabric is 2 mm or more and 5 mm or less when a load of 0.05 kPa is applied from the first surface side using a horizontal plate, the proportion of the contact area between the horizontal plate and the nonwoven fabric under a pressure of 2 kPa to the total surface area of ​​the nonwoven fabric on the first surface side is 55% or less, and the proportion of the contact area between the horizontal plate and the nonwoven fabric under a pressure of 2 kPa to the total surface area of ​​the nonwoven fabric on the second surface side is 55% or more.

[0008] The present invention also provides a method for producing a nonwoven fabric, comprising the steps of: placing a fibrous web on a support having a plurality of convex portions, concave portions arranged between a plurality of the convex portions, and openings arranged at the bottoms of the concave portions, the concave portions extending in a first direction, and the plurality of the convex portions arranged at a distance in a second direction intersecting the first direction; and pressing the fibrous web along the concave portions extending in the first direction by a pressing portion of a pressing member to form an uneven fibrous web; supplying a new fibrous web on top of the uneven fibrous web; pressing the entirety over the new fibrous web with a net; and blowing hot air through the net to fuse the fibers in the uneven fibrous web and the new fibrous web to each other. Furthermore, the present invention provides a method for producing a nonwoven fabric, comprising: a pushing step of placing a fibrous web on a support having a plurality of convex portions, concave portions arranged between a plurality of the convex portions, and openings arranged at the bottoms of the concave portions, the concave portions extending in a first direction, and the plurality of the convex portions being arranged at a distance in a second direction intersecting the first direction, and pushing the fibrous web along the concave portions extending in the first direction by a pushing part of a pushing member to form a concave-convex fibrous web; a first heat fusion step of blowing hot air from above the concave-convex fibrous web to fuse fibers in the concave-convex fibrous web together; and a second heat fusion step of covering the heat-fused nonwoven fabric on a new fibrous web, and blowing new hot air to integrate the new fibrous web and the heat-fused nonwoven fabric by heat fusion. Effect of the Invention

[0009] The nonwoven fabric of the present invention is soft and has good cushioning properties, while being able to maintain its thickness and being difficult to collapse. Furthermore, when the nonwoven fabric of the present invention is used as a surface material for absorbent articles, it not only has a good feel due to its difficulty in collapsing its thickness, but also suppresses liquid returning to the skin. Furthermore, the nonwoven fabric of the present invention can be suitably produced according to the manufacturing method of the nonwoven fabric of the present invention. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1A is a cross-sectional view showing a schematic diagram of a preferred embodiment of the nonwoven fabric according to the present invention, and FIG. 1B is a cross-sectional view showing a modified example of FIG. [Diagram 2] 1(A) to 1(C) are cross-sectional views showing modified examples of the protrusion in FIG. [Diagram 3] FIG. 1 is a partially sectional perspective view that illustrates a preferred embodiment (specific example 1) of the uneven structure in a nonwoven fabric according to the present invention. [Figure 4] FIG. 2 is a partially sectional perspective view that illustrates a schematic diagram of another preferred embodiment (Specific Example 2) of the uneven structure in the nonwoven fabric according to the present invention. [Diagram 5]FIG. 2 is a partially sectional perspective view that illustrates a schematic diagram of another preferred embodiment (Specific Example 3) of the uneven structure in the nonwoven fabric according to the present invention. [Figure 6] FIG. 2 is a partially sectional perspective view that illustrates a schematic diagram of another preferred embodiment (Specific Example 4) of the uneven structure in the nonwoven fabric according to the present invention. [Figure 7] FIG. 1 is an explanatory diagram showing a schematic diagram of a preferred embodiment (first embodiment) of the method for producing a nonwoven fabric according to the present invention, in which (A) shows the pushing process, (B) shows the process of supplying a new fiber web, and (C) shows the heat fusion process. [Figure 8] FIG. 1 is an explanatory diagram showing a schematic diagram of another preferred embodiment (second embodiment) of the method for producing a nonwoven fabric according to the present invention, in which (A) shows the pushing step, (B) shows the step of supplying a new fiber web, and (C) shows the second heat fusion step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A preferred embodiment of the nonwoven fabric according to the present invention will now be described. The nonwoven fabric of the present invention has thermoplastic fibers and has fusion points between fibers at fiber intersections. The fusion points are the parts where the fibers are bonded to each other at the contact points between the intersecting fibers by fusion of the thermoplastic resin component of the fibers themselves. More specifically, the fusion points are formed by melting the surfaces of the thermoplastic fibers, for example, by heat treatment during the manufacturing process of the nonwoven fabric, and fusing the fibers together. Examples of the nonwoven fabric of the present invention include thermal bonded nonwoven fabrics, and more specifically, air-through nonwoven fabrics (nonwoven fabrics in which the fusion points are formed by hot air treatment. Short fibers of 60 mm or less are mainly used.) and spunbonded nonwoven fabrics (nonwoven fabrics in which a resin in a molten state is spun into a nonwoven fabric as it is, and the fusion points are formed by embossing. Long fibers of 100 mm or more are mainly used.) are included. In particular, air-through nonwoven fabrics are preferable from the viewpoint of ensuring the feel and the height of the unevenness.

[0012] The nonwoven fabric of the present invention has a first surface side and a second surface side opposite to the first surface side. The first surface side and the second surface side are the front and back surfaces of the nonwoven fabric, and are the surface furthest from the horizontal surface in the vertical direction relative to the horizontal surface when the nonwoven fabric is placed on the horizontal surface. The first surface side is the surface side that receives pressure during use, and refers to the surface side to be used. The first surface side is the surface side on which the uneven structure is arranged, and the surface side on which the convex portion with the fiber assembly layer arranged therein protrudes. When the nonwoven fabric of the present invention is used as a member such as a top sheet in an absorbent article, the first surface side is the skin side facing the skin, and the second surface side is the non-skin side. The skin side and the non-skin side are defined as indicating a relative positional relationship even when they do not directly contact the skin of the user, etc.

[0013] The nonwoven fabric of the present invention has outer fibrous layers on the first and second sides, in which the fibers are oriented in a planar direction. The outer fibrous layers form the outermost surfaces of the nonwoven fabric on each of the first and second sides, and have flat portions. In addition, the nonwoven fabric of the present invention has a plurality of connecting portions disposed between the outer fibrous layer on the first side and the outer fibrous layer on the second side, in which the fibers are oriented in the thickness direction of the nonwoven fabric. The nonwoven fabric of the present invention is bulky and thick because the connecting parts connect and support the outer fibrous layers on the first and second sides. The thickness referred to here does not refer to the local thickness of the outer fibrous layers or the connecting parts alone, but refers to the apparent thickness between the front and back surfaces of the entire nonwoven fabric in its shaped form (the apparent thickness will be described later).

[0014] The nonwoven fabric of the present invention has an uneven structure on the first surface side, in which convex portions each consisting of the outer fiber layer on the first surface side and the connecting portions and concave portions between the convex portions are alternately arranged. The outer fiber layer on the second surface side forms the bottom of the concave portions. A fiber assembly layer is arranged inside the convex portions on the second surface side. The fiber assembly layer contains thermoplastic fibers, and fusion points between fibers are arranged at fiber intersections.

[0015] The uneven structure of the nonwoven fabric of the present invention can take various forms, for example, as shown in Figures 1(A) and (B). Fig. 1(A) shows a nonwoven fabric 10 having an outer fibrous layer 1 on a first surface side 1A and an outer fibrous layer 2 on a second surface side 1B, and connecting parts 3 connecting the outer fibrous layers 1 and 2. In the nonwoven fabric 10, an uneven structure is arranged on the first surface side 1A, which is composed of protruding parts 4 formed by the outer fibrous layer 1 and the connecting parts 3, and recessed parts 5 between the protruding parts 4, 4. The recessed parts 5 are box-shaped space portions that are open to the first surface side, with the outer fibrous layer 2 as their bottom (recess bottom) and the connecting parts 3 as their wall surfaces. A fiber assembly layer 6 is disposed inside the second surface side 1B of the protrusions 4. The protrusions 4 have a columnar protruding structure having a flat top portion made of the outer surface fiber layer 1 on the first surface side 1A and a wall surface made of the connecting portion 3. That is, the connecting portion 3 in the nonwoven fabric 10 connects the outer surface fiber layers 1 and 2 so as to be perpendicular thereto, and thus the protrusions 4 have a rectangular cross section. In the nonwoven fabric 10, the fiber assembly layer 6 is filled from the second surface side of the top portion of the protrusions 4 to the same depth position as the outer surface fiber layer 2 on the second surface side 1B. That is, the protrusions 4 have a solid structure, and the second surface side of the nonwoven fabric 10 is made flat by the outer surface fiber layer 2 and the fiber assembly layer 6. In Fig. 1(A), the fiber assembly layer 6 is disposed inside the second side 1B of the projections 4 and further extends to the second side 1B of the recesses 5, and the flat outer surface fiber layer 2 on the second side 1B is shown as having a two-layer structure. However, the present invention is not limited to this form, and the fiber assembly layer 6 may remain inside the second side 1B of the projections 4 and not extend to the second side 1B of the recesses 5. In this case, the outer surface fiber layer 2 forming the bottom of the recesses 5 has a single-layer structure extending continuously from the connecting parts 3 (not shown).

[0016] Fig. 1(B) shows a modified example of the nonwoven fabric 10 shown in Fig. 1(A). In the nonwoven fabric 20 shown in Fig. 1(B), the connecting portion 3 and the connecting portions between the outer surface fiber layers 1 and 2 have a curved shape.

[0017] 2(A) to 2(C) show modified examples of the protrusions 4 in the nonwoven fabric 10 of Fig. 1(A). This modified example also applies to Fig. 1(B). 2(A) has a space 7 between the fiber assembly layer 6 and the outer fiber layer 1 (top of the protrusion) on the first surface side 1A of the protrusion 4A. As a result, when the skin touches the protrusion 4A, the space 7 provides a soft cushioning effect until the top of the protrusion 4A hits the fiber assembly layer 6, and the orientation of the fibers in the thickness direction of the connecting parts 3 and the fiber assembly layer 6 make the thickness of the protrusion 4A less likely to be crushed. 2(B) has a recess 61 in the fiber assembly 6 on the second side. Therefore, the nonwoven fabric 10 has an uneven structure on the second side 1B, which is formed by the outer fiber layer 2 and the recess 61 in the fiber assembly layer 6. As a result, the nonwoven fabric 10 has a mechanism on the second side 1B that absorbs and disperses the pressing force applied from the first side 1A, and in addition to being difficult to crush in thickness as described above, it has an even softer cushioning property. In the convex portion 4C shown in Fig. 2(C), the fiber assembly layer 6 has a protruding portion 62 that protrudes further toward the second side 1B from the surface position of the outer fiber layer 2 on the second side 1B. Therefore, the nonwoven fabric 10 has an uneven structure on the second side 1B due to the outer fiber layer 2 and the protruding portion 62 of the fiber assembly layer 6. This allows the nonwoven fabric 10 to achieve the same effect as the case of having the convex portion 4B in Fig. 2(B). In addition, when the nonwoven fabric 10 is used as a topsheet of an absorbent article, the presence of the fiber assembly layer 6 creates a space capable of retaining bodily fluids between the outer fiber layer 2 on the second side 1B and a member such as an absorbent body thereunder, thereby enhancing the function of absorbing bodily fluids in the concave portion 5 on the first side 1A.

[0018] In the nonwoven fabric 10, some of the protrusions 4 may have the form of any one of the protrusions 4A to 4C shown in Figures 2(A) to (C), or all of the protrusions 4 may have the form of any one of the protrusions 4A to 4C shown in Figures 2(A) to (C). In addition, the protrusions shown in Figures 2(A) to (C) may be mixed in one piece of nonwoven fabric.

[0019] In the outer surface fiber layers on the first and second sides, "fibers are oriented in a planar direction" means that the longitudinal orientation rate of the fibers is less than 45% as measured by the measurement method described below. By making the longitudinal orientation rate of the fibers less than 45%, the fibers are sufficiently aligned in the planar direction, and a flat shape can be maintained. From the viewpoint of maintaining the shape and strength of the nonwoven fabric, the outer surface fiber layers oriented in the planar direction preferably have a longitudinal orientation rate of the fibers of 0% or more, and more preferably 30% or more. In addition, it is preferable that the longitudinal orientation rate of the fibers of the outer surface fiber layers on the first and second sides is less than 40% because it is easy to contact with a flat surface like a normal flat nonwoven fabric, and it is more preferable that it is 38% or less, and even more preferable that it is 37% or less. The fiber assembly layer preferably has the same longitudinal orientation rate as that of the outer fiber layer.

[0020] In the connecting portion, "fibers are oriented in the thickness direction of the nonwoven fabric" means that the longitudinal orientation rate of the fibers is 60% or more, as measured by the measurement method described below. When the connecting portion has a longitudinal orientation rate of the fibers in this range, it can be said that the connecting portion is arranged vertically in the thickness direction of the nonwoven fabric of the present invention. The connecting portion has a longitudinal orientation rate of the fibers of 60% or more and has partial fusion between the fibers, so that the connecting portion stands up like a pillar. From the viewpoint of imparting soft and good cushioning properties to the nonwoven fabric, the longitudinal orientation rate of the fibers in the connecting portion is preferably 63% or more, more preferably 65% ​​or more, and even more preferably 68% or more. There is no particular upper limit, but from the viewpoint of forming fusion points by creating intersections between the fibers and forming columns between the fibers to form a structure that can withstand force, the longitudinal orientation rate is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less.

[0021] The outer fiber layers on the first and second sides and the connecting portion are each classified as a region in which the longitudinal orientation rate of the fibers is within the above range. The connecting portion is seamlessly connected to the outer fiber layers on the first and second sides at the end, and therefore, in that portion, fibers oriented in the planar direction and fibers oriented in the thickness direction are mixed. In addition, in the portion in which fibers oriented in the planar direction and fibers oriented in the thickness direction are mixed, it is preferable that the longitudinal orientation rate of the fibers shows an oblique orientation of 45% to 60%, and it is more preferable that the longitudinal orientation rate of the fibers gradually changes from 45% to a sufficient longitudinal orientation rate of 60% or less.

[0022] The fiber assembly layer disposed inside the second surface side of the protrusion is classified as not satisfying the requirement for the longitudinal orientation rate of the fibers in the connecting portion. The fiber assembly layer is classified as a layer having a different fiber density from the outer surface fiber layer on the first surface side. The fiber assembly layer preferably has a fiber density of 70% or less of the outer surface fiber layer on the first surface side. In addition, it is preferable that the fiber assembly layer and the outer surface fiber layer and connecting portion on the first surface side have a difference in the number of fusion points between fibers, fiber density, and fineness that can be visually determined.

[0023] (Method of measuring the longitudinal orientation rate of fibers in the outer fiber layers on the first and second sides and in the connecting parts) The longitudinal orientation ratios of the fibers in the outer fiber layers 1 on the first and second sides and in the connecting portions can be measured based on the following (1) and (2). (1) Preparation of the cross section of the nonwoven fabric A cross section (longitudinal cross section) of the nonwoven fabric passing through the outer fiber layers on the first and second sides is prepared in a thickness direction at a position perpendicular to the direction in which the connecting parts extend in the planar direction and passing through the center of the extending length. Alternatively, a cross section (longitudinal cross section) of the nonwoven fabric passing through the outer fiber layers on the first and second sides is prepared in a thickness direction at a position passing through the center of the recess. Note that the above cross section is cut from the nonwoven fabric to be measured, measuring 5 mm x 5 mm or more in plan view. (2) Measurement of the longitudinal orientation rate of the fibers in the outer fiber layers on the first and second sides and in the connecting parts In the cross section of the nonwoven fabric, the cross sections of the outer fiber layer on the first surface side and the outer fiber layer on the second surface side and the connecting portion are observed at 35 times magnification using an SEM (JCM-6000Plus manufactured by JEOL Ltd.). A square line of 0.5 mm x 0.5 mm is created as a reference line on the observed image. Each side of the square (reference line) is perpendicular to the thickness direction and the planar direction in the cross section of the nonwoven fabric. The square is disposed in a position close to the outer surface of the first surface side in the outer fiber layer and the connecting portion on the first surface side. The square is also disposed in a position close to the outer surface of the second surface side in the outer fiber layer on the second surface side. The total number of fibers passing through the reference line formed by each side of the square is counted. The fibers passing through the reference line of the square perpendicular to the planar direction of the nonwoven fabric are defined as the "number of horizontal fibers," and the fibers passing through the reference line of the square perpendicular to the thickness direction of the nonwoven fabric are defined as the "number of vertical fibers." The longitudinal orientation rate is calculated as (number of vertical fibers) / (number of horizontal fibers + number of vertical fibers) x 100 = longitudinal orientation rate (%). These are measured at four points each, and the average is taken as the longitudinal orientation rate value. The outer fiber layer and connecting parts are each cut out and measured.

[0024] The nonwoven fabric of the present invention has the above-mentioned fiber orientation and uneven structure, and is smooth to the touch, soft elasticity, and is difficult to collapse in thickness. Specifically, the presence of fibers oriented in the planar direction of the outer fiber layer on the first surface side can give a smooth feeling to the skin and disperse pressure. The connecting parts support the outer fiber layer like pillars because the fibers are oriented in the thickness direction of the nonwoven fabric. In addition, the fiber assembly layer supports the outer fiber layer and the connecting parts from the inside and acts to maintain the shape of the convex parts. Furthermore, the fiber assembly layer imparts soft elasticity to the convex parts due to the elasticity of the fibers. In this way, the nonwoven fabric of the present invention has a smooth touch, soft elasticity, and is difficult to collapse in thickness.

[0025] When the nonwoven fabric of the present invention is used as a skin-facing member (a member located on the skin-facing side of the absorbent body that holds liquid) of an absorbent article, such as a top sheet, the concave-convex structure on the first surface side quickly absorbs body fluids in the concaves, and while the fibers have soft and good cushioning properties, the presence of the convex parts that are difficult to crush prevents the skin from touching the liquid absorption path of the concave parts. In addition, the planar orientation of the fibers of the outer surface fiber layer on the first surface side, which forms the outer surface of the convex parts, and the thickness direction of the fibers of the connecting parts provide body fluid induction that directs body fluids toward the concave parts, thereby improving the body fluid concentration in the concave parts. In this way, the place where body fluid enters (concave parts) and the place where the skin comes into contact (convex parts) can be separated under load due to body pressure, so body fluids are unlikely to remain on the skin. In addition, the thickness of the convex parts that are difficult to crush keeps the absorbent body under the top sheet at a distance from the skin, thereby preventing body fluids from returning to the skin from the absorbent body.

[0026] The nonwoven fabric of the present invention has an apparent thickness of 2 mm or more and 5 mm or less under a load of 0.05 kPa. Here, the "apparent thickness" means the vertical distance between a horizontal plane and an imaginary plane (horizontal plate) that is in contact with the outermost part of the side of the nonwoven fabric opposite to the side that is in contact with the horizontal plane when the nonwoven fabric is placed on the horizontal plane (hereinafter, the vertical direction to the horizontal plane may be simply referred to as the "vertical direction"). For example, when the nonwoven fabric of the present invention has an uneven shape on both sides, the apparent thickness is the vertical distance between the position of the apex of the convexity on the first side and the position of the apex of the convexity on the second side. The "apparent thickness" means the thickness when a load of 0.05 kPa is applied from the first surface side using a horizontal plate. Specifically, it can be measured by the following method. Here, the "load of 0.05 kPa" means a load that suppresses fuzzing on the surface of the nonwoven fabric, and is a light load (a light load that is not a compressive force that would crush the thickness of the nonwoven fabric) necessary to properly measure the apparent thickness of the nonwoven fabric. The load of 0.05 kPa is applied to the nonwoven fabric by placing a horizontal plate, for example, a circular plate with a diameter of 2.5 cm and a mass of 2.45 g, on the first surface side of the nonwoven fabric.

[0027] (Method for measuring the apparent thickness of nonwoven fabric under a load of 0.05 kPa) The nonwoven fabric to be measured is cut into 10 cm x 10 cm pieces to prepare a measurement sample. Using a laser thickness gauge (high-precision displacement sensor ZS-LD80 (product name) manufactured by Omron Corporation. All laser thickness gauges used in this specification are of this type), a load of 0.05 kPa is applied to the first surface side of the measurement sample using a horizontal plate, and the thickness is measured in this state. Measurements are taken at three locations, and the average value is regarded as the apparent thickness of the nonwoven fabric to be measured. In addition, when 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 and the above measurement is performed. This method of removing the nonwoven fabric is similarly applied to other measurements in this specification. If it is not possible to take out a piece of nonwoven fabric measuring 10 cm x 10 cm, take out as large a piece as possible.

[0028] The nonwoven fabric of the present invention has an apparent thickness of 2 mm or more under a load of 0.05 kPa, which makes it soft and provides high cushioning properties, and an apparent thickness of 5 mm or less makes it less prone to being crushed. From this viewpoint, the apparent thickness is preferably equal to or greater than 2.2 mm, and more preferably equal to or greater than 2.5 mm. From the same viewpoint, the apparent thickness is preferably equal to or less than 4.8 mm, and more preferably equal to or less than 4.5 mm.

[0029] In addition, in the nonwoven fabric of the present invention, the contact area between the horizontal plate and the nonwoven fabric accounts for 55% or less of the surface area of ​​the nonwoven fabric on the first side. This contact area can be measured by the following method, applying a pressure of 2 kPa. The "surface area of ​​the nonwoven fabric" means the area of ​​the outline of the nonwoven fabric obtained by observing the surface of the nonwoven fabric to be measured from above. Therefore, the area of ​​the part along the undulations of the uneven structure is ignored. The contact area of ​​the first surface side being 55% or less means that the concave portions have a sufficient area for absorbing bodily fluids, and at the same time, the convex portions are prevented from collapsing under a pressure of 2 kPa. This allows the nonwoven fabric of the present invention to have softness and good cushioning properties, while easily maintaining its thickness and being resistant to collapsing. Note that the pressure of 2 kPa is intended to simulate the pressure exerted on the back of a diaper when a young baby (0 years 1 month to 0 years 4 months) wearing the diaper is lying on its back and using the nonwoven fabric of the present invention as the top sheet of the diaper. From the viewpoint of improving breathability, the contact area on the first surface side is preferably 53% or less, and more preferably 50% or less. Also, from the viewpoint of reducing localized stress on the skin, the contact area on the first surface side is preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more.

[0030] (Method of measuring contact area) (1) Cut a measurement sample measuring 70 mm x 70 mm from the nonwoven fabric. (2) Place the measurement sample with the measurement surface facing up. (3) Using a high-precision shape measurement system KS-1100 (product name, manufactured by Keyence Corporation), a laser beam is irradiated onto the measurement surface to measure the surface shape (the height and depth of the thickness that rises and falls along the surface direction of the measurement surface) of the measurement surface in a no-load state (natural state without load) and an image is captured. 2 The measurement pitch is 20 μm × 20 μm, and the moving speed is 10 cm / sec. More specifically, the measurement range is 4 cm 2 The area is divided into sections of 20 μm x 20 μm, and the thickness of each section is measured. (4) Next, a transparent acrylic plate with a mass of 70 g is placed on the measurement surface of the measurement sample, and a weight with a mass of 950 g is further placed on the acrylic plate. Under this condition, a pressure of 2 kPa is applied, and the surface shape of the measurement surface is measured and an image is captured in the same manner as in (3) above. (5) The images captured in (3) and (4) above are analyzed using a shape analysis application called KS-Analyzer (product name, manufactured by Keyence Corporation). Specifically, the area where the thickness changes from the no-load state to the application of a pressure of 2 kPa (minimum measurable scale: 0.1 μm) is extracted and binarized to obtain a surface image of that area. (6) The surface image of the part where the thickness has changed obtained in (3) above is imported and processed using image processing software NewQube (Ver. 4.22, product name, manufactured by Nexus Co., Ltd.), and its area (number of sections of 20 μm × 20 μm units) is measured. This area corresponds to the area of ​​the part that comes into contact with the skin when the nonwoven fabric of the measurement sample is pressurized at 2 kPa, i.e., the contact area. (7) The measured area was divided by the area of ​​the measurement sample (total number of sections: 251,001 sections = 501 × 501)) and expressed as a percentage to calculate the “contact area rate” of the measurement surface of the nonwoven fabric to be measured.

[0031] Furthermore, in the nonwoven fabric of the present invention, the contact area between the horizontal plate and the nonwoven fabric accounts for 55% or more of the surface area of ​​the nonwoven fabric on the second side. This contact area can be measured under the same conditions and by the same method as for the contact area on the first side. The contact area of ​​the second surface side being 55% or more means that this is a preferable contact area for obtaining sufficient bonding strength when bonding to other members. Furthermore, when used as a top sheet of an absorbent article, it is expected to provide sufficient strength and adhesion when bonding to a sublayer or absorbent body. As a result, the nonwoven fabric of the present invention also has high absorption performance. The contact area on the second surface side may be 100% or less, and from the viewpoint of obtaining sufficient bonding strength when bonding to another member, is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more.

[0032] In the nonwoven fabric of the present invention, the fineness of the fiber assembly layer disposed inside the second surface side of the protrusions is preferably greater than the fineness of the connecting portion. This improves the feel of the outer surface of the protrusions, and the presence of the thick fibers inside increases the elasticity of the protrusions. Furthermore, when the nonwoven fabric of the present invention is used as a top sheet of an absorbent article, it further improves the permeability of body fluids into the inside of the protrusions. This allows body fluids that may remain while moving along the surface of the protrusions to the recesses to permeate into the inside of the protrusions, making it even less likely that body fluids will remain on the skin.

[0033] From the viewpoint of the above-mentioned action, the difference (R1-R2) between the fineness (R1) of the fiber assembly layer disposed inside the second surface side of the protrusion and the fineness (R2) of the connecting portion is preferably 1.0 dtex or more, more preferably 1.5 dtex or more, and even more preferably 2.0 dtex or more. From the viewpoint of touch and softness, the difference (R1-R2) between the fineness (R1) of the fiber assembly layer disposed inside the second surface side of the protrusion and the fineness (R2) of the connecting portion is preferably 4.0 dtex or less, more preferably 3.5 dtex or less, and even more preferably 3.0 dtex or less.

[0034] Under the above requirement of the difference (R1-R2), the fiber assembly layer disposed inside the second surface side of the protrusion has a fineness (R1) of preferably 1.8 dtex or more, more preferably 1.9 dtex or more, and even more preferably 2.0 dtex or more. The fiber assembly layer disposed inside the second surface side of the protrusion has a fineness (R1) of preferably 6.0 dtex or less, more preferably 5.8 dtex or less, and even more preferably 5.5 dtex or less. Under the above requirement of the difference (R1-R2), the fineness (R2) of the connecting portion is preferably 1.0 dtex or more, more preferably 1.1 dtex or more, and even more preferably 1.3 dtex or more. The fineness (R2) of the connecting portion is preferably 3.5 dtex or less, more preferably 3.2 dtex or less, and even more preferably 3.0 dtex or less.

[0035] In the nonwoven fabric of the present invention, the fiber density (M1) of the outer fiber layer on the first side of the convex portion (top of the convex portion) is preferably lower than the fiber density (M2) of the outer fiber layer on the second side of the concave portion (bottom of the concave portion). This can simultaneously improve the soft feel of the top of the convex portion and the shape retention of the concave-convex structure due to the high fiber density at the bottom of the concave portion. In addition, when the nonwoven fabric of the present invention is used as a skin-facing member (a member located on the skin-facing side of the absorbent body that absorbs and retains liquid) such as a top sheet or sublayer of an absorbent article, the high fiber density in the concave portion increases the ability of the concave portion to draw in bodily fluids, making it even more difficult for bodily fluids to remain on the skin. In addition, the cushioning property of the skin-facing side of the absorbent article is improved. As a result, the above-mentioned improvement in the feel on the skin and the prevention of bodily fluids remaining can be improved at the same time, and the comfort of the absorbent article can be improved. Furthermore, when the nonwoven fabric of the present invention is used as a top sheet of an absorbent article, the surface area of ​​the nonwoven fabric with the skin is reduced due to its uneven structure that is not easily crushed while still having a soft and good cushioning property, and this state is easily maintained while the nonwoven fabric is worn. This also improves breathability, further improving the comfort of the absorbent article.

[0036] From the viewpoint of the above-mentioned action, the difference (M2-M1) between the fiber density (M2) of the outer surface fiber layer on the second side of the recess (bottom of the recess) and the fiber density (M1) of the outer surface fiber layer on the first side of the protrusion (top of the protrusion) is 80 fibers / mm 2 More than 90 fibers / mm is preferable. 2 More preferably, 100 fibers / mm 2 From the viewpoint of maintaining the thickness and making it difficult to be crushed, the difference (M2-M1) between the fiber density (M2) of the outer surface fiber layer on the second side of the recess (bottom of the recess) and the fiber density (M1) of the outer surface fiber layer on the first side of the protrusion (top of the protrusion) is 250 fibers / mm 2 Less than 220 lines / mm is preferable. 2 Less than 200 lines / mm is more preferable. 2 The following is even more preferred:

[0037] Under the above requirement of the difference (M2-M1), the fiber density (M1) of the outer surface fiber layer (top of the convex portion) on the first surface side of the convex portion is 20 fibers / mm 2More than 30 fibers / mm is preferable. 2 More preferably, 40 fibers / mm 2 The fiber density (M1) of the outer fiber layer on the first surface side of the protrusion (top of the protrusion) is preferably 120 fibers / mm 2 Less than 110 threads / mm is preferable. 2 Less than 100 fibers / mm is more preferable. 2 The following is even more preferred: Under the above requirement of the difference (M2-M1), the fiber density (M2) of the outer fiber layer on the second side of the recess (bottom of the recess) is 120 fibers / mm 2 More than 135 lines / mm is preferable. 2 More preferably, 150 lines / mm 2 The fiber density (M2) of the outer fiber layer on the second surface side of the recess (bottom of the recess) is preferably 300 fibers / mm 2 Less than 275 lines / mm is preferable. 2 Less than 250 lines / mm is more preferable. 2 The following is even more preferred:

[0038] (Method of measuring fiber density of outer fiber layer on first side of convex portion (top of convex portion) and fiber density of outer fiber layer on second side of concave portion (bottom of concave portion)) The fiber density of the outer fiber layer on the first side of the convex portion is within 1 mm 2 The fiber density of the outer fiber layer on the second side of the recess can be calculated by counting the number of fibers per mm 2 It can be calculated by counting the number of fibers per unit area. Specifically, the nonwoven fabric is cut in the thickness direction so as to pass through the tops of the convex parts and the bottoms of the concave parts to be measured. A scanning electron microscope (SEM) is used to enlarge and observe the cut surface, and the number of cut fiber cross sections within a certain area of ​​the cut surface is counted. The magnification for the magnified observation is adjusted to a value (150x or more and 500x or less) that allows the measurement of approximately 30 to 60 fiber cross sections. Next, 2 This is converted into the number of fiber cross sections per unit, and the fiber density (fibers / mm 2) The measurement results at the three locations are averaged to determine the fiber density of the sample. Note that various types of devices can be used as the scanning electron microscope (SEM). For example, JCM-6000Plus (product name) manufactured by JEOL Ltd. can be used.

[0039] The fiber density (M3) of the fiber assembly layer inside the second surface side of the protrusion is set to 40 fibers / mm 2 More than 45 threads / mm is preferable. 2 More preferably, 50 fibers / mm 2 The fiber density (M3) of the fiber assembly layer inside the second surface side of the protrusion is preferably 150 fibers / mm 2 Less than 135 lines / mm is preferable. 2 Less than 120 lines / mm is more preferable. 2 The following is even more preferred: The fiber density (M3) of the internal fiber assembly layer on the second side of the convex portion can be measured by the same method as described above (method of measuring the fiber density of the outer fiber layer on the first side of the convex portion (top of the convex portion) and the fiber density of the outer fiber layer on the second side of the concave portion (bottom of the concave portion)).

[0040] The basis weight of the nonwoven fabric of the present invention is 23 g / m from the viewpoint of maintaining softness and good cushioning properties. 2 More than 24 g / m is preferable. 2 More preferably, 25 g / m 2 From the viewpoint of improving liquid permeability, the basis weight of the nonwoven fabric of the present invention is preferably 40 g / m 2 Less than 38 g / m is preferred 2 Less than 36 g / m is more preferable. 2 The following is even more preferred:

[0041] In the nonwoven fabric of the present invention, various patterns of the uneven structure can be used as long as they do not violate the above-mentioned requirement of the contact area on the first surface side. For example, there are the following nonwoven fabrics 60 (Specific Example 1), 70 (Specific Example 2), 80 (Specific Example 3), and 90 (Specific Example 4). In the nonwoven fabrics having these uneven structures, the above-mentioned requirements can be appropriately incorporated. Specific examples of these concave-convex structures will be described below.

[0042] As shown in FIG. 3, the nonwoven fabric 60 (specific example 1) has a first outer fiber layer 61A extending in the Y direction on the first surface side 1A and arranged at intervals in the X direction intersecting the Y direction. It further has a second outer fiber layer 61B connecting the first outer fiber layers 61A, 61A and extending in the X direction. A first connecting portion 63A extending perpendicularly to the thickness direction is connected to an end of the first outer fiber layer 61A. This forms a first convex portion 64A that protrudes to the first surface side 1A and has a length in the Y direction. In the first convex portion 64A, the first connecting portion 63A extends in the Y direction and forms a wall surface facing the X direction. In addition, a second connecting portion 63B extending perpendicularly to the thickness direction is connected to an end of the second outer fiber layer 61B. This forms a second convex portion 64B that protrudes to the first surface side 1A and has a length in the X direction. In the second protrusion 64B, the second connecting portion 63B extends in the X direction and forms a wall surface facing the Y direction. The first protrusion 64A and the second protrusion 64B both have a rectangular cross section and have a columnar three-dimensional protrusion structure. The X direction and the Y direction can be any direction on the plane of the nonwoven fabric 60. In particular, it is preferable that the Y direction is the longitudinal direction of the nonwoven fabric 60, and the X direction is the transverse direction perpendicular to the longitudinal direction of the nonwoven fabric 60. It is preferable that the longitudinal direction and the transverse direction are the machine direction (MD) and the cross direction (CD) perpendicular to the machine direction during the production of the nonwoven fabric 60. The matters related to the X direction and the Y direction also apply to the following specific examples.

[0043] In a plan view from the first surface side of the nonwoven fabric 60, as described above, two types of convex portions having different extending directions are arranged in a lattice pattern by intersecting with each other. A fiber assembly layer 66 is arranged inside the second surface side 1B of the convex portions arranged in a lattice pattern. The lattice pattern and the solid convex portions prevent not only crushing in the thickness direction but also collapse in the planar direction, making it easier to maintain the uneven shape. The area surrounded by the two types of protrusions is a recess 65 on the first side 1A. A rectangular outer fiber layer 62 on the second side 1B is disposed at the bottom of the recess 65. Two first connecting parts 63A and two second connecting parts 63B are vertically connected to four ends of the outer fiber layer 62 on the second side 1B. The recess 65 forms a box-shaped space open to the first side 1A, and a plurality of recesses 65 are scattered in the planar direction. In the recess 65, the box-shaped space is surrounded by four connecting parts, and the connecting parts are connected to each other at right angles, making it difficult for the recess 65 to be crushed by pressure. The fibers are oriented in the planar direction in the first outer fiber layer 61A and the second outer fiber layer 61B on the first side and the outer fiber layer 62 on the second side. In the first connecting portion 63A and the second connecting portion 63B, the directions in which the walls face (facing directions) are different, but the fibers are oriented in the thickness direction in both cases. This adds to the aforementioned lattice-like protruding structure, making the thickness less likely to collapse, and when used as a top sheet of an absorbent article, bodily fluids are even less likely to remain on the skin. Furthermore, in the nonwoven fabric 60, the first outer fiber layer 61A and the second outer fiber layer 61B, which have different extending directions on the first surface side 1A, preferably have different orientation directions in the planar direction of the fibers. It is more preferable that the fibers in the first outer fiber layer 61A are oriented in the extending direction (Y direction) and the fibers in the second outer fiber layer 61B are oriented in the extending direction (X direction). This makes it more difficult for the projections arranged in a lattice pattern to be crushed.

[0044] In the nonwoven fabric 70 (Specific Example 2), as shown in Fig. 4, four connecting parts (two first connecting parts 73A and two second connecting parts 73B) are connected perpendicularly to the thickness direction to four ends of the rectangular outer surface fiber layer 71 on the first surface side. This forms a columnar protrusion 74 protruding on the first surface side 1A. A plurality of columnar protrusions 74 are scattered in the planar direction. A fiber assembly layer 76 is disposed inside the columnar protrusions 74 on the second surface side 1B. Between the columnar protrusions 74, 74 is a recess 75 on the first surface side 1A. The outer surface fiber layer 72 on the second surface side 1B is disposed at the bottom of the recess 75. The aforementioned connecting portions (first connecting portion 73A and second connecting portion 73B) extending perpendicularly in the thickness direction are connected to the ends of the outer surface fiber layer 72 on the second surface side 1B. The fibers are oriented in the planar direction in the first outer fiber layer 71 on the first side and the outer fiber layer 72 on the second side. In the first connecting portion 73A and the second connecting portion 73B, although the directions in which the walls face (facing directions) are different, the fibers are oriented in the thickness direction in both cases. This makes the thickness less likely to collapse, and when used as a top sheet of an absorbent article, bodily fluids are less likely to remain on the skin and the breathability is excellent.

[0045] In the nonwoven fabric 80 (specific example 3), as shown in FIG. 5, on the first surface side 1A, a plurality of first convex portions 84A in the form of vertical ridges protruding from the first surface side 1A extend in the Y direction and are arranged at intervals in the X direction intersecting the Y direction. The first convex portions 84A in the form of vertical ridges are composed of a first outer surface fiber layer 81A extending in the Y direction of the first surface side 1A and a first connecting portion 83A connected to an end of the first outer surface fiber layer 81A and extending in the thickness direction. The connecting portion between the first connecting portion 83A and the first outer surface fiber layer 81A is curved. In the first convex portions 84A in the form of vertical ridges, the first connecting portion 83A extends in the Y direction and forms a wall surface facing the X direction. In addition, second convex portions 84B in the form of horizontal ridges protruding from the first surface side 1A and extending in the X direction are arranged to connect the first convex portions 84A in the form of vertical ridges. The second convex portion 84B is lower in the thickness direction than the first convex portion 84A, and has a shape in which the top portion is curved toward the second surface side 1B. This second convex portion 84B is composed of a second outer surface fiber layer 81B extending in the X direction of the first surface side 1A, and a second connecting portion 83B connecting to an end portion of the second outer surface fiber layer 81B and extending in the thickness direction. The connecting portion between the second connecting portion 83B and the second outer surface fiber layer 81B is curved. In the horizontal ridge-shaped second convex portion 84B, the second connecting portion 83B extends in the X direction and forms a wall surface facing the Y direction.

[0046] In a plan view from the first surface side of nonwoven fabric 80, the above-mentioned two types of ridge-like convex portions are arranged in a lattice pattern, similar to the above-mentioned nonwoven fabric 60. A fiber assembly layer 86 is arranged inside the second surface side 1B of the convex portions arranged in a lattice pattern. The lattice-like and solid convex portions prevent not only crushing in the thickness direction but also collapse in the planar direction, making it easier to maintain the shape. In the nonwoven fabric 80, similarly to the nonwoven fabric 60 described above, the portion surrounded by the above two types of convex portions is a concave portion 85 on the first surface side 1A. The outer surface fiber layer 82 on the second surface side 1B is disposed at the bottom of the concave portion 85. Two first connecting portions 83A and two second connecting portions 83B are connected in the thickness direction to four ends of the outer surface fiber layer 82 on the second surface side 1B. The connecting portions between the first connecting portions 83A and the second connecting portions 83B and the outer surface fiber layer 82 on the second surface side 1B are curved. The concave portions 85 form a pyramidal space portion open to the first surface side 1A, and are scattered in a plurality in the planar direction. In the concave portions 85, the pyramidal space portion is surrounded by four connecting portions, making it difficult to be crushed by pressure. The fibers are oriented in the planar direction in the first outer fiber layer 81A and the second outer fiber layer 81B on the first side and the outer fiber layer 82 on the second side. In the first connecting portion 83A and the second connecting portion 83B, the directions in which the walls face (facing directions) are different, but the fibers are oriented in the thickness direction in both cases. This adds to the aforementioned lattice-like protruding structure, making the thickness less likely to collapse, and when used as a top sheet of an absorbent article, bodily fluids are even less likely to remain on the skin. Furthermore, in the nonwoven fabric 80, the first outer fiber layer 81A and the second outer fiber layer 81B, which have different extending directions on the first surface side 1A, preferably have different orientation directions in the planar direction of the fibers. It is more preferable that the fibers in the first outer fiber layer 81A are oriented in the extending direction (Y direction) and the fibers in the second outer fiber layer 81B are oriented in the extending direction (X direction). This makes it more difficult for the projections arranged in a lattice pattern to be crushed.

[0047] In the nonwoven fabric 90 (specific example 4), as shown in FIG. 6, a plurality of streak-like protrusions 94 are arranged on the first surface side 1A, extending in the Y direction of the first surface side 1A and spaced apart in the X direction perpendicular to the Y direction. The streak-like protrusions 94 are composed of an outer surface fiber layer 91 extending in the Y direction on the first surface side and a connecting portion 93 connecting an end of the outer surface fiber layer 91 and extending in the thickness direction. The connecting portion between the connecting portion 93 and the outer surface fiber layer 91 is curved, and the streak-like protrusions 94 are ridge-like with rounded corners. The outer surface fiber layer 91 on the first surface side 1A has a ridge-like shape with a height in the thickness direction that gradually rises and falls along the Y direction. In addition, the streak-like protrusions 94 have a shape in which the width in the X direction gently undulates along the Y direction in a plan view (wide portions and narrow portions are alternately connected). A fiber assembly layer 96 is disposed inside the second surface side 1B of the streak-like protrusions 94. Furthermore, the nonwoven fabric 90 has streak-like recesses 95 on the first surface side 1A between the streak-like protrusions 94, 94. An outer surface fiber layer 92 on the second surface side 1B is disposed at the bottom of the recesses 95. A connecting portion 93 is connected to the outer surface fiber layer 92 on the second surface side 1B in the thickness direction. The connecting portion between the connecting portion 93 and the outer surface fiber layer 92 on the second surface side 1B is curved, with rounded corners. In the streaky convex portions 94 containing the fiber assembly layer 96 inside the second surface side 1B, the fibers are oriented in the planar direction in the outer fiber layer 91 on the first surface side and the outer fiber layer 92 on the second surface side. The fibers are oriented in the thickness direction in the connecting portions 93. This makes the thickness less likely to collapse, and when used as a topsheet for an absorbent article, bodily fluids are less likely to remain on the skin and the breathability is excellent.

[0048] Next, preferred embodiments (first embodiment and second embodiment) of the method for producing a nonwoven fabric of the present invention will be described. The manufacturing method of the first embodiment and the manufacturing method of the second embodiment differ in the position and timing of supplying the fiber web that forms the fiber assembly portion described above, but the basic steps of the pushing step for forming unevenness in nonwoven fabric manufacturing and the heat fusion step for forming nonwoven fabric are common. That is, in both embodiments, a fiber web in which the degree of freedom of fiber movement is higher than that of nonwoven fabric is used, and a pushing step for forming unevenness by pressing in a mechanical contact manner using a support and a pushing member, and a heat fusion step (nonwoven fabric forming step) by hot air treatment after forming unevenness are performed. The "fiber web" refers to a fiber assembly in which the constituent fibers are not fused and fixed but are loosely entangled, and which does not have the shape retention of a sheet by itself. In other words, it is a fiber assembly before being made into a nonwoven fabric. Therefore, the mobility between the fibers in the fiber web is high, and the fiber web is highly deformable in the pushing step.

[0049] First, a method for producing the nonwoven fabric of the first embodiment will be described. As shown in FIG. 7, the first embodiment includes the following four steps (hereinafter, each step may be referred to as step (A1), step (A2), step (A3), and step (A4)). (A1) A pressing process, comprising the steps of: (a) placing a fibrous web 100 on a support 110 having a plurality of convex portions 111, concave portions 112 arranged between the plurality of convex portions 111, and openings 113 arranged at the bottom of the concave portions 112, the concave portions 112 extending in a first direction, and the plurality of convex portions 111 arranged at a distance in a second direction intersecting the first direction; and (b) pressing and shaping the fibrous web 100 along the concave portions 112 extending in the first direction by a pressing portion 121 of a pressing member 120, thereby forming a concave-convex fibrous web 101. (A2) A step of supplying a new fiber web 102 onto the uneven fiber web 101. (A3) A process of pressing the entire new fiber web 102 with a net 130. (A4) A heat fusion step in which hot air W1 is blown from above the net 130 to fuse the fibers in the uneven fiber web 101 and the new fiber web 102 together.

[0050] In step (A1), as shown in FIG. 7(A), the fiber web is directly pressed by mechanical pressure. This causes the fiber web to be shaped into irregularities that conform to the shape of the support. In addition, compared to pressing with non-mechanical pressure such as wind, the fibers are strongly oriented, and an orientation perpendicular to the nonwoven fabric plane can be obtained. In addition, it is not necessary to apply a large pressing force to increase the height difference of the irregularities formed on the fiber web, and the fiber web can be shaped softly. In addition, fiber disorder can be suppressed to improve shaping properties. In this step (A1), the pressing depth can be appropriately set to form the apparent thickness of the nonwoven fabric of the present invention. Also, the arrangement of the protrusions 111 of the support 110 and the pressing parts 121 of the pressing member 120 can be appropriately set to provide the contact area of ​​the nonwoven fabric of the present invention.

[0051] The extending direction of the recesses 112 of the support 110 is preferably the machine flow direction (the rotation direction of the drum-shaped support 110). This allows the fiber web 100 pressed into the recesses 112 to form protrusions extending in the machine flow direction. Furthermore, it is preferable that the recesses 112 also extend in the width direction (the direction of the rotation axis of the drum shape) perpendicular to the machine flow direction. This allows the formation of lattice-shaped protrusions. Furthermore, it is preferable that the support 110 applies negative pressure from the circumferential surface to the inside. This allows the fiber web 100 and the uneven fiber web 101 aligned along the circumferential surface of the support 110 to be sucked, and the aligned state to be maintained better before moving to the next process.

[0052] In step (A2), a new fiber web 102 is supplied to the uneven fiber web 101 laid along the peripheral surface of the support 110. As a result, the new fiber web 102 fills the pressed-in portion of the uneven fiber web, as shown in Fig. 7(B), and the pressed-in portion is solidified.

[0053] The fineness of the fiber web 100 to be used here and to be shaped into irregularities is preferably the fineness (R2) of the above-mentioned connecting portion, and the fineness of the new fiber web 102 is preferably the fineness (R1) of the above-mentioned fiber assembly layer. The basis weight of the fiber web 100 to be formed with unevenness is set to 8 g / m from the viewpoint of maintaining the thickness and making it difficult to be crushed. 2 More than 9g / m is preferable. 2 More preferably, 10 g / m 2 The basis weight of the fiber web 100 having the irregularities is preferably 20 g / m2 or more from the viewpoint of improving the liquid permeability. 2 Less than 17 g / m is preferred. 2 Less than 15 g / m is more preferable. 2 The following is even more preferred: In addition, the basis weight of the new fiber web 102 is set to 10 g / m2 in order to maintain good cushioning properties. 2 More than 11g / m is preferable. 2 More preferably, 12 g / m 2 The basis weight of the new fiber web 102 is preferably 22 g / m2 or more from the viewpoint of improving the feel and cushioning. 2 Less than 21 g / m is preferred. 2 Less than 20 g / m is more preferable. 2 The following is even more preferred:

[0054] 7(C), on the peripheral surface of the support 110, the laminate 103 of the uneven fiber web 101 and the new fiber web 102 is pressed down by a net 130 from above the new fiber web 102. This makes it possible to prevent the fibers of the uneven fiber web 101 and the new fiber web 102 from scattering when hot air is blown in step (A4).

[0055] Next, in step (A4), as shown in Fig. 7(C), hot air W1 is blown from above the net 130 onto the laminate 103 arranged along the peripheral surface of the support 110 to fuse the fibers in the uneven fiber web 101 and the new fiber web 102 together. This step (A4) is performed at the position of the hot air blowing section 140. The support 110 preferably has a hot air suction section 141 at a position facing the hot air blowing section 140 inside the drum. This results in a nonwoven fabric 700 according to the present invention having a concave-convex structure in which fiber assemblies 6 are arranged inside the protrusions 4. At this time, by blowing hot air W1 at a high temperature and low speed, the new fiber web 10 can easily enter the concaves of the concave-convex fiber web 101 and the side onto which the hot air W1 is blown can be made flat. The nonwoven fabric 700 according to the present invention thus obtained has a low basis weight but is bulky and has solid protrusions 4.

[0056] 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. 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 maintaining good cushioning properties and thickness. Also, 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.

[0057] In the nonwoven fabric 700 according to the present invention obtained through the above-mentioned steps of the first embodiment, the side facing the support is the first side 1A having an uneven structure in which convex portions 4 consisting of an outer fiber layer 1 and connecting portions 3 and concave portions 5 between the convex portions 4, 4 are alternately arranged. The side onto which the hot air W1 is blown is the second side 1B on which the outer fiber layer 2 and the fiber assembly layer 6 are arranged. In the first embodiment, the surface onto which the hot air W1 is blown (the second surface side) is held down by the net 130, increasing the fiber density on that surface. This allows the fiber density of the outer fiber layer on the first surface side of the convex portions in the nonwoven fabric of the present invention to be lower than the fiber density of the outer fiber layer on the second surface side of the concave portions. The difference in fiber density can be appropriately set by the pressing force of the net 130, the wind speed of the hot air W1, etc.

[0058] Next, a method for producing the nonwoven fabric of the second embodiment will be described. As shown in FIG. 8, the second embodiment includes the following three steps (hereinafter, each step may be referred to as step (B1), step (B2), and step (B3)). (B1) A pressing process, in which a fiber web 100 is placed on a support 110 having a plurality of convex portions 111, concave portions 112 arranged between the plurality of convex portions 111, and openings 113 arranged at the bottom of the concave portions 112, the concave portions 112 extending in a first direction, and the plurality of convex portions 111 arranged at a distance in a second direction intersecting the first direction, and the fiber web 100 is pressed and shaped by a pressing portion 121 of a pressing member 120 along the concave portions 112 extending in the first direction, thereby forming a concave-convex fiber web 101. (B2) A first heat fusion step in which hot air W1 is blown onto the uneven fiber web 101 to fuse the fibers in the uneven fiber web 101 together. (B3) A second heat-sealing step in which the heat-sealed nonwoven fabric 104 is placed on top of a new fiber web 102, and new hot air W2 is blown thereon to integrate the new fiber web 102 and the heat-sealed nonwoven fabric 104 by heat sealing.

[0059] As shown in FIG. 8(A), the step (B1) is the same as the step (A1) in the above-described first embodiment. Step (B2) is a step of performing step (A4) in the above-described first embodiment in a state where a new fiber web 102 is not supplied. By this step (B2), the uneven fiber web 101 becomes a heat-fused nonwoven fabric (intermediate nonwoven fabric) 104 before a new fiber web 102 is supplied. At this time, the net 130 may or may not be present. The temperature and wind speed of the hot air W1 in the second embodiment may be the same as or different from those in the first embodiment. However, since the hot air W1 in the second embodiment is blown in a state where there is no new fiber web 102, it is preferable to set the temperature and wind speed of the hot air W1 as follows. That is, in the second embodiment, the temperature of the hot air W1 is preferably 135° C. or more, more preferably 140° C. or more, and even more preferably 145° C. or more, from the viewpoint of thermally fusing the thermoplastic fibers and stabilizing the shape of the nonwoven fabric. The temperature of the hot air W2 is preferably 185° C. or less, more preferably 180° C. or less, and even more preferably 175° C. or less, from the viewpoint of suppressing excessive thermal fusing 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 maintaining good cushioning properties and thickness, and 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.

[0060] Next, in step (B3), the heat-fused nonwoven fabric 104 is placed on the new fiber web 102 to form a laminate 205. As a result, as shown in Fig. 8(B) , the new fiber web 102 fills the parts of the heat-fused nonwoven fabric 104 that were supported by the protruding parts 111 of the support 110, and the new fiber web 102 is solidified. Furthermore, in step (B3), the laminate 205 is placed on the net 170 in the fusion furnace 160 with the new fiber web 102 side facing down, and new hot air W2 is blown onto it from above. This causes the new fiber web 102 and the heat-fused nonwoven fabric 104 to be integrated together, as shown in Fig. 8(C). This provides the nonwoven fabric 800 according to the present invention, which has a concavo-convex structure in which the fiber assembly parts 6 are arranged inside the convex parts 4.

[0061] The temperature of the hot air W2 is preferably 130° C. or higher, more preferably 133° C. or higher, and even more preferably 135° C. or higher, from the viewpoint of thermally fusing the thermoplastic fibers of the new fiber web 102 and integrating them with the nonwoven fabric 104 to stabilize the shape. Moreover, the temperature of the hot air W2 is preferably 170° C. or lower, more preferably 165° C. or lower, and even more preferably 160° C. or lower, from the viewpoint of suppressing excessive thermal fusing of the thermoplastic fibers and improving the softness of the nonwoven fabric. In addition, the wind speed of the hot air W2 is preferably 1.5 m / sec or less, more preferably 1.0 m / sec or less, and even more preferably 0.8 m / sec or less, from the viewpoint of maintaining good cushioning properties and thickness. Also, the wind speed of the hot air W2 is preferably 0.1 m / sec or more, more preferably 0.2 m / sec or more, and even more preferably 0.3 m / sec or more, from the viewpoint of thermally fusing the thermoplastic fibers of the new fiber web 102 and integrating them with the nonwoven fabric 104 to stabilize the shape.

[0062] In the nonwoven fabric 800 according to the present invention obtained through the above-mentioned steps of the second embodiment, the side opposite to the side facing the support (the side into which the push-in portion 121 is pushed) becomes the first side 1A having an uneven structure in which convex portions 4 consisting of the outer surface fiber layer 1 and the connecting portions 3 and concave portions 5 between the convex portions 4, 4 are alternately arranged. In other words, the side onto which the hot air W1 and the hot air W2 are blown becomes the first side. The side onto which a new fiber web 102 is arranged and which faces the net 170 becomes the second side 1B on which the outer surface fiber layer 2 and the fiber assembly layer 6 are arranged. In the second embodiment, since the net 170 is pressed in step (B3), the fiber density is increased on that surface. At this time, the pressing force of the net 170 used in step (B3) is made larger than the pressing force of the net 130 used in step (B2), and the difference can be set appropriately. This allows the fiber density of the outer fiber layer on the first surface side of the convex portion to be lower than the fiber density of the outer fiber layer on the second surface side of the concave portion, and the difference can be set within a desired range.

[0063] In the first and second embodiments, it is preferable to have a cooling process after blowing the hot air W1. In the first embodiment, as shown in FIG. 7, it is preferable to arrange the cooling section 150 having a cooling nozzle and the cooling and suction section 151 inside the drum of the support 110 opposite each other at a position where the nonwoven fabric 700 according to the present invention obtained by blowing the hot air W1 is aligned along the outer periphery of the drum of the support 110. In the second embodiment, as shown in FIG. 8, it is preferable to arrange the cooling section 150 having a cooling nozzle and the cooling and suction section 151 inside the drum of the support 110 opposite each other at a position where the nonwoven fabric 104 after heat fusion obtained by blowing the hot air W1 is aligned along the outer periphery of the drum of the support 110. As a result, as described above, the support 1 can be kept at a certain temperature or lower, and the obtained nonwoven fabric can be peeled off while maintaining its shape, and good cushioning properties can be maintained.

[0064] In the first and second embodiments, the above-mentioned pressing step (step (A1), step (B1)) and the heat fusion step (step (A4), step (B2) and step (B3)) can be performed under various conditions, etc. For example, the various conditions, etc. described in paragraphs

[0010] to

[0067] of the specification of JP 2019-112747 A can be appropriately adopted. The support 110 and the pressing member 120 used in the pressing step can also be of various shapes. 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-shaped 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 rotation direction and the rotation axis direction. As a result, the concave portions extend at least in the rotation direction of the support. Furthermore, the concave portions also extend in the rotation axis direction. The pressing member shown in FIG. 3 has a pressing portion that is inserted along the concave portions of the support on the drum-shaped circumferential surface. As a result, the pressing portions are arranged in a lattice shape. The spaces between the pressing portions are hollow, forming square-shaped spaces. The pressing member shown in FIG. 7 is a belt-shaped member formed by weaving string-shaped pressing portions in a lattice shape. The pressing member shown in FIG. 8 is a drum-shaped member formed by combining a plurality of rings in the rotation axis direction, and the ring portion forms a pressing portion extending in the rotation direction.

[0065] In the manufacturing method of the first embodiment, the nonwoven fabric 60 (specific example 1) described above can be manufactured using the support of Fig. 2 in JP 2019-112747 A and the pushing member of Fig. 3 or 7 described in the same document. In addition, the nonwoven fabric 80 (specific example 3) described above can be manufactured by using the pushing member of Fig. 8 described in the above document. In the manufacturing method of the second embodiment, the nonwoven fabric 70 (Specific Example 2) described above can be manufactured using the support of Fig. 2 described in JP 2019-112747 A and the pushing member of Fig. 3 or 7 described in the same document. In addition, the nonwoven fabric 90 (Specific Example 4) described above can be manufactured by using the pushing member of Fig. 8 described in the above document.

[0066] Next, the thermoplastic fibers constituting the nonwoven fabric of the present invention will be described. The thermoplastic fibers may be any fibers that are commonly used as materials for nonwoven fabrics without any particular limitations. For example, they may be fibers made of a single resin component or composite fibers made of multiple resin components. Composite fibers may have, for example, a core-sheath structure or a side-by-side structure. When using composite fibers containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air blown onto the fiber web in the manufacturing process is preferably equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component. More preferably, the temperature is equal to or higher than the melting point of the low melting point component and 10°C lower than the melting point of the high melting point component, and even more preferably, the temperature is 5°C or higher than the melting point of the low melting point component and 20°C or lower than the melting point of the high melting point component. In terms of elasticity, the more the core of the core-sheath structure composite fibers have, the higher the elasticity. Therefore, it is preferable that the core component is larger in terms of cross-sectional area ratio. A specific example of a composite fiber having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component is a composite fiber having a core-sheath structure in which the sheath is a polyethylene resin (hereinafter also referred to as PE) and the core is a polyethylene terephthalate resin (hereinafter also referred to as PET). Furthermore, in composite fibers with a core-sheath structure, when the resin component of the sheath has a lower glass transition point than the resin component of the core (hereinafter referred to as a low-glass transition point resin component; for example, the resin component of the core is PET and the resin component of the sheath is PE), the thickness recovery of the nonwoven fabric can be further improved by reducing the mass ratio of the low-glass transition point resin component.

[0067] Such a 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 pads. Absorbent articles typically have a liquid-permeable top sheet, a back sheet, and an absorbent sandwiched between them. The nonwoven fabric of the present invention can be particularly suitably used as a top sheet. Furthermore, the nonwoven fabric can also be used as a sheet in the gather part, an exterior sheet, or a sheet in the wing part of an absorbent article. The nonwoven fabric of the present invention can also be used as a component of an eye mask or a mask. EXAMPLES

[0068] The present invention will be described in more detail below based on examples, but the present invention is not limited thereto. In the examples, "parts" and "%" are all based on mass unless otherwise specified.

[0069] Example 1 Based on the manufacturing method of the first embodiment described above, the nonwoven fabric shown in Fig. 5 was produced under the following conditions and used as nonwoven fabric sample S1 of Example 1. As shown in Fig. 5, the side with the vertical ridges and horizontal ridges was set as the first surface side. In the above production, the fiber web 100 used in the pushing step of step (A1) is a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) thermoplastic fiber with a fineness of 1.3 dtex and a basis weight of 15 g / m 2 The new fiber web 102 supplied in the step (A2) was a fiber web having a basis weight of 15 g / m2 using thermoplastic fibers of a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) having a fineness of 4.4 dtex. 2 The fiber web was obtained as follows. In the pressing step of step (A1), the fiber web 100 was fixed onto a breathable support 110 having a large number of protrusions. The MD pitch of the convex parts (protrusions) 111 of the support 110 in plan view was 5 mm, the CD pitch was 5 mm, and the protrusion height was 3.5 mm. The hole diameter of the holes 112 in the support 110 was 2 mm. Next, the shaped fiber web 100 and a new fiber web 102 were overlapped, and hot air W1 at a temperature of 160° C. and a wind speed of 3 m / sec was blown thereon to fuse the thermoplastic fibers together, thereby producing a nonwoven fabric sample S1.

[0070] Example 2 The fiber web 100 used in the pushing step of step (A1) has a fineness of 1.8 tex and a basis weight of 15 g / m 2 The new fiber web 102 provided in step (A2) has a fineness of 1.8 dtex and a basis weight of 15 g / m 2A nonwoven fabric sample S2 of Example 2 was produced in the same manner as in Example 1, except that:

[0071] Comparative Example 1 A nonwoven fabric sample of Example 1 described in JP 2019-44320 A (sample shown in Figure 1 of the same document) was prepared, and this was used as nonwoven fabric sample C1 of Comparative Example 1. At that time, shaping was performed by forming the fiber web into two layers, an upper layer and a lower layer. The upper layer was made of thermoplastic fiber with a fineness of 1.3 dtex and a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) with a basis weight of 10 g / m 2 The lower layer was a fiber web of 20 g / m2 using thermoplastic fibers of a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) with a fineness of 4.4 dtex. 2 A fiber web of 100 mm was used. The surface of the nonwoven fabric sample of Comparative Example 1 having the vertical ridges and horizontal ridges was the first surface side. The vertical ridges and horizontal ridges were hollow with no fiber assembly layer disposed inside the second surface side.

[0072] Comparative Example 2 A nonwoven fabric sample of Example 1 described in JP 2014-12913 A (sample shown in Figure 1 of the same document) was produced under the following conditions, and this was designated as nonwoven fabric sample C2 of Comparative Example 2. In this production, a core-sheath type thermoplastic fiber with a fineness of 1.8 dtex (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5: 5 (mass ratio), average fiber length 51 mm) and a core-sheath type thermoplastic fiber with a fineness of 4.4 dtex (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5: 5 (mass ratio), average fiber length 51 mm) were mixed so that the basis weight ratio was 1: 1, and a basis weight of 30 g / m was obtained. 2 The fiber web was fed from two carding machines to a shaping device so that the fiber web was shaped as described above. In this shaping device, the fiber web was fixed onto a support 110 having a large number of convex parts (protrusions) and having air permeability. The MD pitch of the convex parts (protrusions) 111 of this support 110 in plan view was 8 mm, the CD pitch was 5 mm, and the convex part (protrusion) height was 3.5 mm. The hole diameter of the hole 112 in the support 110 was 2.8 mm. Next, a first hot air (temperature 160°C, wind speed 50 m / sec) was blown onto the fiber web on the support 110 to shape it, and the fiber web was shaped along the convex portions (protrusions) 111 on the support 110, and the blowing was switched to a second hot air having a temperature of 135°C and a wind speed of 1 m / sec to fuse the fibers of each core-sheath structure.

[0073] For the nonwoven fabric samples of each of the above examples and comparative examples, the longitudinal orientation rate, apparent thickness, contact area ratio between the first side and the second side, and fiber density at the top of the convex portion and the bottom of the concave portion of the outer fiber layer and the connecting portion of the first side and the second side were measured. The results are shown in Table 1 below. The measurements were performed using the above-mentioned (method of measuring the longitudinal orientation rate of the fibers in the outer fiber layers on the first and second sides and in the connecting parts), (method of measuring the apparent thickness of the nonwoven fabric under a load of 0.05 kPa), (method of measuring the contact area), and (method of measuring the fiber density of the outer fiber layer on the first side of the convex part (top of the convex part) and the fiber density of the outer fiber layer on the second side of the concave part (bottom of the concave part)).

[0074] The following tests were carried out on each of the above examples and comparative examples, and the results are shown in Table 1 below. The following tests were performed on diaper samples prepared using each nonwoven fabric sample. The diaper samples were prepared as follows. That is, the top sheet was removed from a commercially available baby diaper (product name "Meries Sarasa Air Through M size", manufactured by Kao Corporation), and instead, nonwoven fabric test pieces cut to 100 mm x 250 mm from each of the above-mentioned nonwoven fabric samples were stacked and fixed around the periphery to obtain a baby diaper sample for evaluation. At this time, the first surface side of the nonwoven fabric test piece was placed facing up. (1) KES compression test (compressive deformation (mm) under a load of 0.15 to 2.5 kPa) In order to measure the amount of compression deformation, a KES compression tester (KES FB-3, manufactured by Kato Tech Co., Ltd.) was used, and the nonwoven fabric was evaluated for compression characteristics with a pressing load of up to 5 kPa in normal mode, except that the terminal speed was set to 0.1 mm / sec., and the amount of deformation from 0.15 to 2.5 kPa was extracted and used as the measured value. The higher the value, the more the nonwoven fabric sinks in response to the load applied by a person to touch it. The larger this value, the more the compression is felt and the more cushioning it has. More specifically, the larger this value, the more difficult it is to crush in the compression direction with a small load, which means that it has high shape retention and is also moderately elastic. Also, the larger the value, the more easily it is crushed under a load of 2.5 kPa, and the larger the value, the more it deforms when touched, making it easier to feel the cushioning. (2) Liquid return test An acrylic plate with a cylindrical injection port was placed on the top sheet, and a weight of 2 kg was placed on the acrylic plate on each of the back side and ventral side of the diaper to apply a load. The injection port provided on the acrylic plate was cylindrical (height 53 mm) with an inner diameter of 36 mm, and a through hole with an inner diameter of 36 mm was formed at 1 / 3 of the longitudinal position and at the center of the width direction of the acrylic plate, whose axis coincides with the center of the cylindrical injection port and communicates between the inside of the cylindrical injection port and the surface of the acrylic plate facing the top sheet. The acrylic plate was placed on the top sheet so that the central axis of the injection port was located approximately in the center of the diaper sample, and a total amount of 160 g of artificial urine was injected. The artificial urine was injected in four separate doses of 40 g at 10-minute intervals. Ten minutes after the fourth injection, the acrylic plate was removed, and 16 sheets of filter paper (Toyo Roshi Kaisha, No. 5C (φ100 mm)) were placed on top of the surface sheet with a side of 100 mm centered on the point where the artificial urine was injected, and a load of 3.5 kg was applied to an area of ​​100 mm × 100 mm to allow the filter paper to absorb the artificial urine. After 2 minutes, the load was removed and the mass (W2) of the filter paper that had absorbed the artificial urine was measured, and the difference (W2-W1) between this and the mass (W1) of the filter paper before absorption, which had been measured in advance, was calculated as the amount of liquid returning. The above procedure was carried out three times, and the average of the three measurements was taken as the amount of liquid returning (mg). The smaller the amount of liquid returning, the less likely it was to cause liquid returning, and the higher the evaluation.

[0075] [Table 1]

[0076] As shown in Table 1, the nonwoven fabric sample C2 of Comparative Example 2, which has a longitudinal orientation rate of less than 60% at the connecting portion, has a contact area ratio of 62% on the first side and 30% on the second side under a pressure of 2 kPa, whereas the nonwoven fabric samples S1 and S2 of Examples 1 and 2 have a contact area ratio of the first side that is 20% or more smaller and a contact area ratio of the second side that is 2.7 times or more larger, and the convex portions are less likely to be crushed. At the same time, the nonwoven fabric samples S1 and S2 of Examples 1 and 2 have a deformation amount value by the KES compression test that is more than twice as large as the nonwoven fabric sample C2 of Comparative Example 2. That is, the nonwoven fabric samples S1 and S2 of Examples 1 and 2 have a soft and good cushioning property, while having a moderate elasticity to maintain their thickness and are less likely to be crushed compared to the nonwoven fabric sample C2 of Comparative Example 2. In addition, the nonwoven fabric sample C1 of Comparative Example 1 had a contact area ratio on the second surface side of 45%, while the nonwoven fabric samples S1 and S2 of Examples 1 and 2 had a contact area ratio on the second surface side of 1.8 or more. As a result, the nonwoven fabric samples S1 and S2 of Examples 1 and 2 provided sufficient support for the base of the pressurized convex parts, especially the connecting parts having a high longitudinal orientation rate, and had a lower contact area ratio on the first surface side than the nonwoven fabric sample C1 of Comparative Example 1, and the shape retention of the convex parts was high. At the same time, the nonwoven fabric samples S1 and S2 of Examples 1 and 2 had a higher deformation amount value in the KES compression test than the nonwoven fabric sample C1 of Comparative Example 1. That is, the nonwoven fabric samples S1 and S2 of Examples 1 and 2 were soft and had good cushioning properties, while having moderate elasticity to maintain their thickness and were less likely to be crushed than the nonwoven fabric sample C1 of Comparative Example 1. Furthermore, the nonwoven fabric samples S1 and S2 of Examples 1 and 2 had a higher contact area ratio on the second surface side and a higher longitudinal orientation rate of the connecting portion than the nonwoven fabric samples C1 and C2 of Comparative Examples 1 and 2, and reduced the amount of liquid return by approximately 30% or more, demonstrating a high effect of preventing liquid return. [Explanation of symbols]

[0077] 1, 71, 91 Outer fiber layer on the first side 61A, 81A: First outer fiber layer on the first surface side 61B, 81B: Second outer fiber layer on the first surface side 2, 62, 72, 82, 92 Outer fiber layer on the second side 3, 93 connection part 63A, 73A, 83A 1st connection part 63B, 73B, 83B 2nd connection part 4, 4A, 4B, 4C, 74, 94 convex part 64A, 84A First protrusion 64B, 84B second convex part 5, 65, 75, 85, 95 recess 6, 66, 76, 86, 96 Fiber assembly 10, 60, 70, 80, 90 Nonwoven fabric 1A 1st side 1B 2nd side 110 Support 120 Push-in member 130, 170 Net 140 Hot air blowing section 160 Fusion Furnace

Claims

1. A nonwoven fabric having thermoplastic fibers, fusion points between the fibers being arranged at fiber intersections, and having a first surface side and a second surface side that is an opposite surface side to the first surface side, an outer surface fiber layer on the first surface side and the outer surface fiber layer on the second surface side, the fibers of which are oriented in a planar direction; and a plurality of connecting portions disposed between the outer surface fiber layer on the first surface side and the outer surface fiber layer on the second surface side, the fibers of which are oriented in a thickness direction of the nonwoven fabric; The first surface side has an uneven structure in which convex portions formed of the outer surface fiber layer and the connecting portions on the first surface side and concave portions between the convex portions are alternately arranged, and the outer surface fiber layer on the second surface side forms the bottom of the concave portions, A fiber assembly layer is disposed inside the second surface side of the protrusion, The nonwoven fabric has an apparent thickness of 2 mm or more and 5 mm or less when a load of 0.05 kPa is applied from the first surface side using a horizontal plate, A nonwoven fabric, wherein the proportion of the contact area between the horizontal plate and the nonwoven fabric under a pressure of 2 kPa to the total surface area of ​​the nonwoven fabric on the first side is 55% or less, and the proportion of the contact area between the horizontal plate and the nonwoven fabric under a pressure of 2 kPa to the total surface area of ​​the nonwoven fabric on the second side is 55% or more.

2. The nonwoven fabric according to claim 1 , wherein the fiber assembly layer has a fineness greater than that of the connecting portions.

3. 3. The nonwoven fabric according to claim 1, wherein the fiber density of the outer fiber layer on the first side of the protrusions is lower than the fiber density of the outer fiber layer on the second side of the recesses.

4. The nonwoven fabric according to any one of claims 1 to 3, wherein a space is provided between the fiber assembly layer and an outer fiber layer on the first surface side of the convex portion.

5. The nonwoven fabric according to any one of claims 1 to 4, wherein the longitudinal orientation rate of the fibers in the connecting portions is 60% or more.

6. a pressing step of placing a fiber web on a support having a plurality of protruding portions, recessed portions arranged between the plurality of protruding portions, and openings arranged at the bottoms of the recessed portions, the recessed portions extending in a first direction, and the plurality of protruding portions arranged at a distance in a second direction intersecting the first direction, and pressing and shaping the fiber web along the recessed portions extending in the first direction by a pressing portion of a pressing member to form a concave-convex fiber web; Supplying a new fiber web on the uneven fiber web; a step of pressing the entire new fiber web with a net; and a heat fusion step of blowing hot air from above the net to fuse the fibers in the uneven fiber web and the new fiber web together.

7. a pressing step of placing a fiber web on a support having a plurality of protruding portions, recessed portions arranged between the plurality of protruding portions, and openings arranged at the bottoms of the recessed portions, the recessed portions extending in a first direction, and the plurality of protruding portions arranged at a distance in a second direction intersecting the first direction, and pressing and shaping the fiber web along the recessed portions extending in the first direction by a pressing portion of a pressing member to form a concave-convex fiber web; a first heat fusion step of blowing hot air onto the uneven fiber web to fuse the fibers in the uneven fiber web together; A method for producing a nonwoven fabric, comprising: a second heat-sealing step of covering a new fiber web with the heat-sealed nonwoven fabric and blowing new hot air thereon to integrate the new fiber web and the heat-sealed nonwoven fabric by heat-sealing.

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