Nonwoven fabric

Abstract

To provide a nonwoven fabric capable of achieving a thickness-retaining property of the nonwoven fabric and soft elasticity when being touched at micro load such as being stroked by a palm of a hand or a fingertip.SOLUTION: A nonwoven fabric has an uneven structure having a plurality of convex parts and bottom parts disposed between the convex parts adjacent to each other and is provided with a fiber fused part. Each of the plurality of convex parts has an apex and wall parts to support the apex. Fibers in the wall part are vertically oriented. Constituent fibers of the uneven structure include a splittable conjugate fiber constituted by continuously disposing two or more types of resins having different melting points as constituents of the fiber in a longer direction of the fiber and alternately disposing the resins along a circumferential direction of the fiber so that the resins can be separated away. The resins alternately disposed along the circumferential direction of the splittable conjugate fiber include a first heat fusible resin and a second heat fusible resin having higher melting point than the first heat fusible resin. A first fiber fused part is disposed at a fiber intersection between the first heat fusible resin and other fiber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to nonwoven fabrics. [Background technology]

[0002] Nonwoven fabrics come in a variety of structures. For example, Patent Document 1 describes a nonwoven fabric used as a surface sheet for an absorbent article, which has a plurality of ridges and a bottom portion, with openings provided in the bottom portion. Patent Document 2 describes a nonwoven fabric as a surface sheet for an absorbent article, comprising napped fibers in which some of the constituent fibers have free ends. The same document also describes a nonwoven fabric having a recess including a joint between two fiber sheets and a protrusion surrounded by the recess, in which the napped fibers are arranged between the fiber sheets in the protrusion. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-467 [Patent Document 2] Japanese Patent Publication No. 2013-27686 [Overview of the project] [Problems that the invention aims to solve]

[0004] The nonwoven fabrics described in Patent Documents 1 and 2 above have cushioning properties due to their respective uneven structures. Furthermore, in the nonwoven fabric described in Patent Document 1, the thickness retention is enhanced by the orientation of the fibers in the wall region to be substantially perpendicular to the bottom. As a result, the nonwoven fabric has a reassuring texture due to its thickness. However, in addition to the above-mentioned thickness retention in the non-woven fabric, the softness with elasticity when touched is also required to be further improved as one of the characteristics of the fiber structure of the non-woven fabric. For example, the soft elasticity during contact with a minute load such as stroking with the palm or fingertips brings about a plump touch feeling of the non-woven fabric, leading to further improvement in the texture. In recent years, achieving both retention of the thickness of the non-woven fabric and improvement in the soft elasticity during the above-mentioned minute load has been more strongly demanded from the perspective of improving the texture of the non-woven fabric. In this regard, in conventional non-woven fabrics, when the thickness retention is high, there is a limit to further enhancing the elasticity when touched, and there is room for improvement from the perspective of further improving the cushioning property.

[0005] In view of the above points, the present invention relates to a non-woven fabric that enables both retention of the thickness of the non-woven fabric and soft elasticity during contact with a minute load such as stroking with the palm or fingertips.

Means for Solving the Problems

[0006] The present invention provides a non-woven fabric having an uneven structure including a plurality of convex portions and a bottom portion provided between adjacent convex portions, and including a fiber fusion portion, wherein each of the plurality of convex portions includes a top portion and a wall portion supporting the top portion, the fibers of the wall portion are vertically oriented, and the constituent fibers of the uneven structure include split-type composite fibers in which two or more types of resins having different melting points are continuously arranged in the longitudinal direction of the fibers as constituent components of the fibers and the respective resins are alternately arranged along the circumferential direction of the fibers, and the resins alternately arranged along the circumferential direction of the split-type composite fibers include a first heat-fusing resin and a second heat-fusing resin having a higher melting point than the first heat-fusing resin, and the fiber fusion portion is arranged at the fiber intersection between the first heat-fusing resin and other fibers.

Effects of the Invention

[0007] The non-woven fabric of the present invention realizes both retention of the thickness of the non-woven fabric and soft elasticity during contact with a minute load such as stroking with the palm or fingertips.

Brief Description of the Drawings

[0008] [Figure 1] It is a cross-sectional view schematically showing a preferred embodiment of the nonwoven fabric according to the present invention. [Figure 2] It is an enlarged perspective view schematically showing an embodiment of a split-type composite fiber in an undivided state. [Figure 3] (A) and (B) are plan views schematically showing a fiber fusion part including split-type composite fibers, and (C) is a plan view schematically showing a fiber fusion part between other fibers than split-type composite fibers. [Figure 4] It is a drawing substitute photograph showing an example of an alternating arrangement of the first resin and the second resin in the circumferential direction in the cross section of the split-type composite fiber. [Figure 5] (A) is a plan view schematically showing a fiber fusion part between conventional thermoplastic fibers (core-sheath composite fibers) other than split-type composite fibers when forming a wall part, and (B) is a drawing substitute photograph thereof. [Figure 6] (A) is a plan view schematically showing a fiber fusion part (fiber intersection fusion part) including split-type composite fibers in the wall part of the nonwoven fabric of the present embodiment, and (B) is a drawing substitute photograph thereof. [Figure 7] It is a plan view schematically showing a state in which the split-type composite fiber has a split part and a non-split part. [Figure 8] (A) to (D) are cross-sectional views schematically showing modes of the presence states of the respective resins in the split part of the split-type composite fiber. [Figure 9] (A) to (C) are cross-sectional views schematically showing modes of the presence states of the respective resins in the non-split part of the split-type composite fiber. [Figure 10] It is a partially cutaway perspective view schematically showing a specific example of the nonwoven fabric shown in FIG. 1. [Figure 11] It is a cross-sectional view taken along line R1-R1 of the nonwoven fabric shown in FIG. 10. [Figure 12] It is a cross-sectional view taken along line R2-R2 of the nonwoven fabric shown in FIG. 10. [Figure 13] It is a cross-sectional view taken along line R3-R3 of the nonwoven fabric shown in FIG. 10. [Figure 14]This is a schematic process diagram illustrating a part of a preferred manufacturing method for the nonwoven fabric of this embodiment, where (A) shows the step of placing the fiber web on the male support material, (B) shows the step of pressing down on the fiber web with the female support material to shape it and treating it with hot air using a first hot air, and (C) shows the step of removing the female support material from the shaped fiber web and treating it with hot air using a second hot air. [Figure 15] This is a plan view of the male support member. [Figure 16] This is a plan view of the female support material. [Figure 17] This is a plan view showing the male support material and female support material combined. [Modes for carrying out the invention]

[0009] A preferred embodiment of the nonwoven fabric according to the present invention will be described below with reference to the drawings. The nonwoven fabric 10 in this embodiment is a so-called thermal bond nonwoven fabric having fiber fusion portions at the intersections of fibers. For example, an air-through nonwoven fabric is one in which the fiber fusion portions are formed by an air-through method.

[0010] As shown in Figure 1, the nonwoven fabric 10 of this embodiment has a front side 10T and a back side 10B. The nonwoven fabric 10 has a plurality of protrusions 1 projecting from one side 10T and a bottom portion 2 provided between adjacent protrusions 1, 1. As a result, the nonwoven fabric 10 has an uneven structure in the thickness direction Z. The protrusions 1 are three-dimensional fiber layers erected in the thickness direction Z of the nonwoven fabric 10 and are located higher on one side 10T than the bottom portion 2. The bottom portion 2 is a fiber layer at the bottom of a recess in the other side 10B between the protrusions 1, 1 and forms the outer surface of the other side 10B. Each of the plurality of protrusions 1 includes a top portion 1A and a wall portion 1B that supports the top portion 1A.

[0011] The outer shape of one side 10T of the top portion 1A and the other side 10B of the bottom portion 2 may be flat or curved. One side 10T of the top portion 1A is preferably a dome-shaped curved surface from the viewpoint of making the feel softer when it is the skin-contacting surface that comes into contact with the wearer's skin. The other side 10B of the bottom portion 2 is preferably a flat surface from the viewpoint of increasing stability as a base that supports the thickness of the nonwoven fabric 10, and from the viewpoint of improving fixation with the absorbent when the nonwoven fabric 10 is used as a surface sheet and improving the transfer of excretory fluid.

[0012] The fibers of the wall portion 1B of the protrusion 1 are oriented longitudinally with respect to the bottom portion 2. This means that the fibers of the wall portion 1B are oriented longitudinally with respect to the planar direction of the nonwoven fabric 10. Planar orientation of the nonwoven fabric 10, as used here, means the direction along the plane (e.g., a flat base) that is in contact with the surface of the other side 10B of the nonwoven fabric 10 (bottom portion 2). This longitudinal orientation of the fibers increases the thickness-direction support of the wall portion 1B with respect to the top portion 1A and bottom portion 2, allowing for softer load absorption and making it easier to maintain the thickness of the protrusion 1 of the nonwoven fabric 10 even under load. It also improves the thickness recovery of the protrusion 1 when the load is removed. As a result, the nonwoven fabric 10 has improved thickness retention and feels resilient. Furthermore, when the nonwoven fabric 10 is used as a component on the skin side of an absorbent article, such as a surface sheet, the effect of fluid permeation of bodily fluids is more easily sustained even under load, and fluid return from the absorbent to the skin side (wet back) is suppressed.

[0013] The longitudinal orientation of the fibers in the wall portion 1B means that there are many fibers along the thickness direction Z of the nonwoven fabric 10, and that the longitudinal orientation rate obtained by the measurement method described later is 60% or more. From the viewpoint of further enhancing the above effect, 60% or more is more preferable, and 63% or more is even more preferable. Furthermore, there is no particular upper limit to the longitudinal orientation rate, but from the viewpoint of creating intersections between fibers to form fusion points and creating a columnar structure that can withstand force, 90% or less is preferable, 85% or less is more preferable, and 80% or less is even more preferable.

[0014] (Method for measuring the longitudinal orientation ratio of fibers in wall section 1B) As shown in Figure 1, measurements are taken on wall section 1B using the following procedure. Specifically, the fiber layer cross-section of the wall portion 1B, defined in the thickness direction cross-section of the nonwoven fabric 10 including the convex portion 1 and the bottom portion 2, is observed by magnifying it 50 times with a SEM. A square line with sides of 50 μm is drawn on the observed image as a reference line. Each side of the square (reference line) is defined as a side perpendicular to the thickness direction and the plane direction, respectively, in the cross-section of the nonwoven fabric 10. The total number of fibers passing through the reference line formed by each side of the square is counted. Fibers passing through the square reference line perpendicular to the plane direction of the nonwoven fabric are defined as "transverse fiber count," and fibers passing through the square reference line perpendicular to the thickness direction of the nonwoven fabric 10 are defined as "longitudinal fiber count." The longitudinal orientation rate is calculated as (longitudinal fiber count) / (transverse fiber count + longitudinal fiber count) × 100 = longitudinal orientation rate (%). These are measured at three points, and the average is taken as the longitudinal orientation rate value. The planar direction in the cross-section of the nonwoven fabric 10 corresponds to the straight line L connecting the lower surfaces of adjacent bottom portions 2 (i.e., the straight line L tangent to the surface of the other side 10B of the nonwoven fabric 10), as shown in Figure 1. The thickness direction corresponds to the direction perpendicular to the straight line L.

[0015] In the cross-section of the nonwoven fabric 10 in the thickness direction, including the convex portion 1 and the bottom portion 2, the fiber layer of the wall portion 1B can be demarcated by drawing a boundary line with the fiber layers of the top portion 1A and the bottom portion 2 in the following manner. Specifically, a nonwoven fabric having a cross-section in the thickness direction including a top portion 1A and a bottom portion 2 is placed on the base of a microscope VHX6000 (product name, manufactured by Keyence Corporation) with the bottom portion 2 (the other side 10B) facing downwards. Next, a flat plate (for example, a flat acrylic plate) is placed on the top portion 1A side (the other side 10T) of the nonwoven fabric and a load of 0.05 kPa is applied. In this state, the cross-section in the thickness direction is observed at 20x magnification using the microscope, and the fiber layer in the part in contact with the base is designated as the bottom portion 2, the fiber layer in the part in contact with the flat plate as the top portion 1A, and the fiber layer in the part connecting the end of the top portion 1A and the end of the bottom portion 2 as the wall portion 1B. In identifying the wall portion 1B, the thicknesses of the top portion 1A and the bottom portion 2 in the area where the wall portion 1B is absent are defined as the thicknesses of the ends of the top portion 1A and the ends of the bottom portion 2, respectively, and the portion excluding these thicknesses is defined as the wall portion 1B.

[0016] In addition, the constituent fibers of the above-mentioned uneven structure include segmented composite fibers. A "segmented composite fiber" refers to a fiber in which two or more types of resins with different melting points are continuously arranged as constituent components of the fiber in the longitudinal direction (fiber length direction), and each resin is arranged alternately along the circumferential direction of the fiber, and the resins are configured to be separable from each other. Of the two or more types of resins, some of the resins are first heat-fusible resins that form the fiber fusion portion, and the remaining resins are second heat-fusible resins with a higher melting point than the first heat-fusible resins. The term "separable" means that in a cross-section along the direction perpendicular to the fiber length direction of the segmented composite fiber, each resin component is divided into multiple parts, and by applying heat and / or external force to the fiber, the resins can be separated from each other. By arranging resin components with different melting points alternately along the circumferential direction of the fiber, adjacent resins are less likely to fuse together and are more likely to separate.

[0017] The following explanation will use a split-type composite fiber as an example, in which the first and second heat-fusible resins are composed of two types of resins (components) with different melting points: a first resin and a second resin with a higher melting point than the first resin. However, in the nonwoven fabric of the present invention, the split-type composite fiber may contain three or more types of resins with different melting points. In any case, some of the resins are the first heat-fusible resins that form the fiber fusion portions, and the remaining resins are the second heat-fusible resins with a higher melting point.

[0018] The segmented composite fiber 5 shown in Figure 2 includes a first resin 51 and a second resin 52, which have two different melting points. The first resin 51 is a heat-fusible resin (e.g., polyethylene resin) capable of forming fiber fusion portions. The second resin 52 is a heat-fusible resin (e.g., polyethylene terephthalate resin) with a higher melting point (lower thermal fusion properties) than the first resin 51 and capable of maintaining the fiber shape. The first resin 51 and the second resin 52 are arranged continuously in the longitudinal direction (fiber length direction) of the segmented composite fiber 5 and alternately along the circumferential direction W of the fiber. In the cross-section of the fiber, the first resin 51 and the second resin 52 form multiple arc-shaped portions along the circumferential direction W, and are arranged radially from the center of the cross-section toward the outer circumference. In Figure 2, the outer surface of the segmented composite fiber 5 is formed by four arc-shaped portions made of the first resin 51 and four arc-shaped portions made of the second resin 52. Note that in Figure 2, a pattern is shown on the second resin 52 to illustrate the arrangement of the first resin 51 and the second resin 52, but this does not represent the actual presence of such a pattern.

[0019] Thus, the segmented composite fiber 5 contains a first resin (first heat-fusible resin) 51 and a second resin (second heat-fusible resin) 52 having a higher melting point than the first resin, arranged alternately along the circumferential direction W. That is, the first resin 51 and the second resin 52 are arranged alternately along the circumferential direction W. In Figure 2, the cross-section of the segmented composite fiber 5 is shown as a perfect circle, but it is not limited to this and may be a non-circular shape. Examples of non-circular shapes include geometric shapes such as ellipses, triangles, squares, pentagons, and hexagons, or other convex polygons or regular polygons. When the segmented composite fiber 5 has segmented and non-segmented parts, as described later, the shape of the cross-section of the segmented composite fiber 5 described above refers to the shape of the non-segmented part.

[0020] As described above, the nonwoven fabric 10 has fiber fusion portions 7 at the intersections of fibers. The fiber fusion portions 7 include fiber fusion portions (also called fiber intersection fusion portions) 71 located at the fiber intersections between the first resin 51, which is a heat-fusible resin of the divided composite fiber 5, and other fibers (other divided composite fibers 5 or other types of fibers 8) (Figures 3(A) and (B)). Among the four arc-shaped portions of the first resin 51, the first resin 51 located at the fiber intersection 6 melts, thereby forming the fiber intersection fusion portion 71 with other fibers (other divided composite fibers 5 or other types of fibers 8).

[0021] The fiber intersections 6 that form the fiber intersection fusion portion 71 include fiber intersections 61 between split-type composite fibers 5 and fiber intersections 62 between split-type composite fibers 5 and other types of fibers (for example, thermoplastic fibers such as core-sheath type thermoplastic fibers) 8 (Figure 3(A), (B)). In addition, the fiber fusion portion 7 of the nonwoven fabric 10 may or may not include fiber fusion portions 72 at fiber intersections 81 between other types of fibers 8 different from the split-type composite fibers 5 (Figure 3(C)).

[0022] The fiber intersection fusion portions 71 and 72 are dispersed three-dimensionally within the fiber structure of the nonwoven fabric 10. In the fiber intersection fusion portions 71 and 72, the resin constituting the fibers melts due to heat and pressure, or the boundary between each fiber at the intersection of the fibers becomes unclear.

[0023] (Method for checking the fiber fusion joint 7) First, the nonwoven fabric to be measured is frozen with liquid nitrogen to fix the state of the fibers. Next, the frozen nonwoven fabric is cut using a razor blade or the like so that the cross-sections of the constituent fibers are formed, and a measurement sample is prepared. Subsequently, the cross-section of the measurement sample is observed using a microscope or SEM at any magnification sufficient to recognize the cross-sections of the constituent fibers and measure the dimensions of the fiber cross-sections. By observing the presence or absence of the molten state described above, the presence or absence of fiber fusion portions 7 can be determined. In this case, the magnification can be, for example, 100 times. This observation method is also applied to the observation methods in other measurement methods described herein.

[0024] Fiber 8 is a conventional thermoplastic fiber, different from the segmented composite fiber 5, and more than half of the outer circumference of the cross-section of fiber 8 is composed of heat-fusible resin. Examples include core-sheath composite fibers or side-by-side composite fibers, which are composite fibers other than the segmented composite fiber 5, and which are composed of two types of thermoplastic resins with different shrinkage rates. The shape of the cross-section of fiber 8 can be any of the various geometric shapes described above. In contrast, the segmented composite fiber 5 has a first resin (first heat-fusible resin) 51 and a second resin (second heat-fusible resin) 52 arranged alternately in the circumferential direction W, resulting in a smaller exposed area of ​​the first heat-fusible resin on the outer surface of the fiber compared to the conventional fiber 8. Therefore, the segmented composite fiber 5 has a structure in which the fusion area at the fiber intersection fusion portion 71 (Figures 3(A) and (B)) with other fibers is reduced compared to the fusion area at the fiber fusion portion 72 (Figure 3(C)) between conventional fibers 8. This difference in fusion area is particularly noticeable in the wall portion 1B where the fibers are vertically oriented.

[0025] The first resin 51 is a thermoplastic resin that forms the fiber intersection fusion portion 71, and from the viewpoint of improving the fusion properties and increasing the strength of the nonwoven fabric 10, it is preferably a thermoplastic resin with a melting point of 160°C or lower, and more preferably a thermoplastic resin with a melting point of 140°C or lower. Furthermore, the second resin 52 is preferably a thermoplastic resin, more preferably a thermoplastic resin with a melting point exceeding 140°C, even more preferably a thermoplastic resin having a melting point 10°C or higher than the melting point of the first resin, and even more preferably a thermoplastic resin having a melting point 20°C or higher than the melting point of the first resin.

[0026] In Figure 2, the number of divisions (number of arc-shaped portions) of the alternatingly arranged first resin 51 and second resin 52 is set to a total of 8 divisions. However, the number of resin divisions in the cross-section of the segmented composite fibers contained in the nonwoven fabric 10 is not limited to this. From the viewpoint of reducing the area of ​​the fiber intersection fusion portion 71, the number of divisions is preferably 4 or more, and more preferably 8 or more. Furthermore, from the viewpoint of maintaining a nonwoven fabric strength that can withstand practical use, the number of divisions is preferably 48 or less, more preferably 32 or less, and even more preferably 16 or less.

[0027] (Method for measuring the number of divisions in segmented composite fiber 5) The number of resin segments in the cross-section of the segmented composite fiber 5 can be measured by the following method. First, a measurement sample is prepared using the same method as described above (method for confirming the fiber fusion portion 7). Next, the cross-section of the measurement sample is observed using a microscope or SEM at any magnification sufficient to recognize the cross-sections of the constituent fibers and measure the dimensions of the fiber cross-sections (see, for example, Figure 4). The number of resin segments in the cross-section is measured visually. In this case, the magnification can be, for example, 100 times. If the divided composite fiber 5 has divided portions where the resins described later are completely separated and undivided portions where they are not completely separated, the observation should be performed on the undivided portions.

[0028] For example, thermoplastic resins can be used in combination as the constituent resin of the segmented composite fiber 5. Specifically, two or more different resins can be used as the constituent resin of the segmented composite fiber, such as polyolefin resins like polyethylene (hereinafter also referred to as PE) and polypropylene (hereinafter also referred to as PP); polyester resins like polyethylene terephthalate (hereinafter also referred to as PET); polyamide resins like nylon 6 and nylon 66; vinyl resins like polyvinyl chloride and polystyrene; acrylic resins like polyacrylic acid and polymethyl methacrylate; and copolymers thereof.

[0029] Examples of combinations of the first resin 51 (first thermoplastic resin) and the second resin 52 (second thermoplastic resin), which have different melting points, include polyethylene / polypropylene, polyethylene / polyethylene terephthalate, polypropylene / polyethylene terephthalate, polyethylene / nylon 6, polypropylene / nylon 6, and nylon 6 / polyethylene terephthalate, which can be expressed as "first resin / second resin". However, the combination of constituent resins is not particularly limited as long as the effects of the present invention are achieved.

[0030] Of these, the first resin 51 is preferably polyethylene, and more preferably high-density polyethylene, from the viewpoint of melting at a relatively low temperature and bonding the fibers well. The second resin 52 is preferably polyethylene terephthalate or polypropylene, from the viewpoint of being less prone to deformation even after heat bonding treatment and obtaining a plump, highly flexible nonwoven fabric. Furthermore, polyethylene terephthalate is more preferably used from the viewpoint of having a high elastic modulus of the resin itself, which can further increase the flexibility of the nonwoven fabric.

[0031] The melting point of the resin can be calculated from the DSC curve measured in accordance with JIS K7121 (1987). In detail, the melting point of a resin can be measured using a differential scanning calorimetry meter (Hitachi High-Tech Science Corporation, DSC7000x (product name)). First, a finely shredded fiber sample (1 mg) is subjected to thermal analysis at a heating rate of 10°C / min to measure the melting peak temperature of each resin. The melting point is defined as the melting peak temperature during the first heating. If the melting point cannot be clearly measured by this method, the resin is defined as a "resin without a melting point." In the case of a resin without a melting point, the softening point is used as the melting point.

[0032] In this way, in the nonwoven fabric 10, the heat-fusible resin exposed on the outer surface of the segmented composite fiber 5 is limited to the first resin 51, so the fusion area at the fiber intersection fusion portion 71 is reduced. As the fusion area is reduced, the area in which the constituent fibers are constrained at the fiber intersection 6 is suppressed. As a result, in the three-dimensional network structure of fibers formed by the fiber fusion portion 7, the mobility of the constituent fibers starting from the fiber intersection fusion portion 71 is increased. Consequently, the nonwoven fabric 10, while being resistant to thickness collapse due to the longitudinal orientation of the fibers in the wall portion 1B as described above, possesses a gentle elasticity starting from the fiber intersection fusion portion 71 of the fibers due to the reduction in the fusion area. In particular, in the wall portion 1B, the longitudinal orientation makes it easier for the fibers to come into contact with each other over a surface, and the segmented composite fibers 5 have a high effect in reducing the area of ​​fusion. That is, in the case of conventional thermoplastic fibers (for example, core-sheath type thermoplastic fibers), the entire outer circumference of the fiber is covered with heat-sealable resin, and the fibers 8 in the wall portion 1B are fused together over a surface along the longitudinal direction of the fiber, as shown in Figures 5(A) and (B), forming a surface fiber fusion portion 72. In contrast, in the nonwoven fabric 10 of this embodiment, the segmented composite fibers 5 form fiber intersection fusion portions 71 in a part of the first resin 51 in the circumferential direction. Therefore, even if the fibers are longitudinally oriented in the wall portion 1B, the area of ​​fusion is reduced (Figures 6(A) and (B)). As a result, the wall portion 1B has a structure that simultaneously possesses resistance to crushing in thickness due to the longitudinal orientation of the fibers, and gentle mobility and elasticity between fibers due to the reduction in the area of ​​fusion between longitudinally oriented fibers. As a result, the nonwoven fabric 10 of this embodiment achieves both the ability to maintain the thickness of the nonwoven fabric and soft elasticity when subjected to minute loads such as those applied by stroking with the palm or fingertips. Consequently, the aforementioned elastic thickness of the nonwoven fabric 10 feels more flexible and plump, possessing excellent cushioning properties while maintaining high thickness retention.

[0033] In the present invention, the compression characteristics under the above-mentioned minute load are values measured by the following method and are defined as characteristic values representing the cushioning feeling. It has been found that the compression characteristic value under the minute load has a correlation with the cushioning feeling. The higher the (compression) characteristic value under the minute load, the easier it is to be crushed with a small load (the part touched with a finger or the like is likely to be indented), and it can represent the goodness of the feeling of experiencing the cushioning feeling of a human.

[0034] (Measurement method of compression characteristic value under minute load) The measurement is carried out under the environment of 22°C and 65% RH. For the measurement of the data used for calculating the compression characteristic value under the minute load, KES FB3-AUTO-A (trade name) manufactured by Kato Tech Co., Ltd. was used. Cut three pieces of the non-woven fabric to be measured into 20 cm × 20 cm to prepare measurement samples. Next, place one of the measurement samples on the test bench with the surface facing up. Next, compress it between steel plates having a circular plane with an area of 2 cm 2 . The compression speed is 20 μm / sec, and the maximum compression load is 9.80 cN / cm 2 (10.0 gf / cm 2 ), and the recovery process is also measured at the same speed. At this time, the displacement amount between the steel plates is set as x (mm), the load is set as y (cN / cm 2 ), and the position of the point where the load is detected is set as x = 0, and measurement is carried out in the compression direction. The value of x increases as it is compressed. The compression characteristic value under the minute load is calculated by extracting the amount of deformation of the thickness under the minute load from the measured data (x, y). Specifically, in the first time not in the recovery process, the data of the load between 0.29 cN / cm 2 (0.30 gf / cm 2 ) and 0.98 cN / cm 2 (1.00 gf / cm 2 ) and the amount of deformation at that time are extracted, an approximate straight line for the relationship between x and y is obtained by the least squares method, and the slope at that time is taken as the above-mentioned characteristic value (unit (cN / cm 2 ) / mm). Measure three places with one measurement sample. Perform a total of nine measurements on three samples. Calculate the characteristic value for each of the nine places, and take the average value of them as the compression characteristic value of the non-woven fabric under the minute load. When measuring nonwoven fabrics, if the nonwoven fabric to be measured is used as a component of an absorbent article and is joined to other components by adhesive or fusion, it is preferable to remove the joints with other components before removing the nonwoven fabric from the absorbent article, rather than forcibly peeling it off. Methods for removing such joints include, for example, applying a solvent, blowing hot air with a dryer, or spraying with a cold spray (for example, a commercially available product from Nichiban Co., Ltd.). In particular, from the viewpoint of avoiding deterioration of the nonwoven fabric to be measured as much as possible, it is preferable to spray a cold spray on the joints between the nonwoven fabric to be measured and other components before peeling off the nonwoven fabric to be measured. This method of removing nonwoven fabrics is also applied to other measurements in this specification.

[0035] In the nonwoven fabric 10, the compression characteristic value under the above minute load is set to 1.7 (cN / cm²) from the viewpoint of enhancing flexibility and soft elasticity when in contact with a minute load. 2 Preferably 2.0 (cN / cm²) / mm or more, and 2.0 (cN / cm²) 2 ) / mm or more is more preferable, and 2.2(cN / cm 2 A value of ) / mm or more is even more preferable. Furthermore, there is no particular upper limit to the compression characteristic value at the above minute load, but from the viewpoint of maintaining a smooth texture, 10(cN / cm) is preferable. 2 Preferably 8 (cN / cm) / mm or less. 2 ) / mm or less is more preferable, and 5(cN / cm 2 A value of ) / mm or less is even more preferable.

[0036] In the nonwoven fabric 10, the proportion of fiber fusion portions 7 (fiber intersection fusion portions 71) containing segmented composite fibers 5 within the fiber fusion portions 7 included in the wall portion 1B is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. This further enhances the aforementioned gentle mobility and elasticity between fibers. Furthermore, among the fiber fusion portions 7 included in the wall portion 1B, the proportion of fiber fusion portions 7 (fiber intersection fusion portions 71) containing segmented composite fibers 5 is preferably 98% or less, more preferably 95% or less, and even more preferably 90% or less, from the viewpoint of increasing the strength of the nonwoven fabric.

[0037] (Method for measuring the number ratio of fiber fusion sections 7 (fiber intersection fusion sections 71) containing segmented composite fibers 5 within the fiber fusion sections 7 included in the wall section 1B) (1) First, the nonwoven fabric to be measured is frozen with liquid nitrogen to fix the state of the fibers. Next, a sample for measurement is prepared by cutting perpendicular to the thickness direction Z using a razor blade or the like so that a cross-section of the center of the wall portion 1B in the thickness direction Z is formed. (2) The cross-section of the measurement sample is imaged using an electron microscope (JCM-6000Plus (product name), manufactured by JEOL Ltd.) under the following imaging conditions. (Imaging conditions) Magnification: 300x Shooting direction: The cross-section of the central part of wall section 1B in the thickness direction Z is photographed from one side 10T. (3) Visually count the fused areas containing segmented composite fibers (Figure 3 (A) and (B)) and the fused areas between other types of fibers different from segmented composite fibers (Figure 3 (C)) from the cross-sectional images. The number of fused areas to be counted should be 160 or more (since there is a limit to the number of fused areas that can be counted from a single image, use many images to count so that the total is 160 or more). The proportion of fused sections containing segmented composite fibers to the total number of fused sections counted is calculated and used as the proportion of fiber fused sections 7 (fiber intersection fused sections 71) containing segmented composite fibers 5 within the fiber fused sections 7 included in wall section 1B.

[0038] It is preferable that the proportion of segmented composite fibers 5 among the constituent fibers of the wall portion 1B is 15% or more. This increases the proportion of fiber intersection fused portions 71 in the fiber fused portions 7, thereby further enhancing the aforementioned gentle mobility and elasticity between fibers. From this viewpoint, the proportion of segmented composite fibers 5 among the total number of constituent fibers of the wall surface 1B is more preferably 20% or more, even more preferably 30% or more, and even more preferably 40% or more. Similarly, from the same viewpoint, it is preferable to have 95% or less, and more preferably 90% or less. Furthermore, it is preferable that the ratio of the number of divided composite fibers 5 to the total number of constituent fibers of the nonwoven fabric 10 is within the above range.

[0039] (Method for measuring the proportion of split composite fibers among the constituent fibers of wall section 1B) (1) First, a measurement sample is prepared by the same method as in (1) above (Method for measuring the number ratio of fiber fusion parts 7 (fiber intersection fusion parts 71) that include divided composite fibers 5 among the fiber fusion parts 7 included in the wall part 1B). (2) The imaging is performed under the same conditions as in (2) above (Method for measuring the ratio of the number of fiber fusion parts 7 (fiber intersection fusion parts 71) that include segmented composite fibers 5 among the fiber fusion parts 7 included in the wall part 1B), except that the imaging magnification is changed from 300x to 500x. (3) Visually inspect all fibers whose cross-sections can be seen from the cross-sectional image, determine whether they are segmented composite fibers or other types of fibers, and count the number of each. The total number of fibers to be counted should be 80 or more (since there is a limit to the number of fibers that can be counted from one image, use many images to count so that the total is 80 or more). Calculate the ratio of segmented composite fibers to the total number of fibers counted, and use this as the ratio of segmented composite fibers 5 among the constituent fibers of wall section 1B.

[0040] In the wall section 1B, the inclusion of segmented composite fibers 5 reduces the fusion area of ​​the fiber fusion section 7. From the viewpoint of further enhancing the aforementioned gentle mobility and elasticity between fibers by reducing the fusion area, the fusion area of ​​the fiber fusion section 7 in the wall section 1B is set to 100 mm². 2 The following is preferable: 70mm 2 The following is more preferable: 50mm 2 The following is even more preferable. Furthermore, the fusion area of ​​the fiber fusion portion 7 in the wall portion 1B should be 1 mm from the viewpoint of increasing the strength of the nonwoven fabric. 2 The above is preferable, 3 mm 2 The above is more preferable, 5 mm 2 The above is even more preferable.

[0041] (Method for measuring the fusion area of ​​the fiber fusion portion 7 in the wall portion 1B) Ten rectangular samples are prepared by cutting out a rectangular area from the nonwoven fabric to be measured, measuring 4 mm vertically and 7 mm horizontally from wall 1B, along the entire thickness. The surface of each sample is imaged at 300x magnification using an electron microscope (JCM-6000Plus (product name), manufactured by JEOL Ltd.). In the electron microscope imaging described above, the focus is set on the outermost layer of fibers on the imaging surface of the measurement sample. For each measurement sample, 10 different locations are photographed, and a total of 30 electron microscope images are obtained for three measurement samples. A colorless, transparent sheet (e.g., an OHP sheet) is placed on the surface of the electron microscope images, and the electron microscope images are observed visually through the colorless, transparent sheet. If a fiber fusion area is present, the outline of the fiber fusion area is traced with a writing instrument such as a pen to mark it so that the fiber fusion area 7 and its surrounding area can be distinguished. Then, the area of ​​the fiber fusion area 7 in the electron microscope image is measured using commercially available image analysis software (product name "Image-Pro Plus 6.2J").

[0042] In the nonwoven fabric 10, it is preferable that the segmented composite fiber 5 includes segments 53 formed by completely separating at least one pair of adjacent resins, and unsegmented segments 54 where all adjacent resins are not completely separated (Figure 7). The segmented segments 53 and unsegmented segments 54 are arranged alternately along the longitudinal direction of the segmented composite fiber 5. Hereinafter, segments 5 having segmented segments 53 and unsegmented segments 54 are referred to as segmented segmented composite fiber 5, and segments without segmented segments 53 are referred to as unsegmented segmented composite fiber 5. Note that the unsegmented segments 54 are not included in the fiber fusion segments 7 of the present invention.

[0043] The divided portion 53 is preferably configured according to one of the following embodiments (i) to (v), as shown in Figures 8(A) to (D). These embodiments may be the same or different in each divided portion 53. (i) A configuration in which the first resin 51 and the second resin 52 adjacent to the first resin 51 are completely separated, and the resins 51 and 52 are not in contact with each other (see Figure 8(A)). (ii) A configuration in which a portion of the first resin 51 constituting the segmented composite fiber 5 peels off, etc., and is completely separated from the adjacent second resin 52 (see Figure 8(B)). (iii) A configuration in which a portion of the second resin 52 constituting the segmented composite fiber 5 peels off, etc., and is completely separated from the adjacent first resin 51 (see Figure 8(B)). (iv) When focusing on one first resin 51, it is completely separated from one adjacent second resin 52, but not completely separated from the other adjacent second resin 52, and a part of the constituent resin peels off, resulting in a state in which it is completely separated from the adjacent resin (see Figures 8(C) and (D)). (v) When focusing on one second resin 52, it is completely separated from one adjacent first resin 51, but not completely separated from the other adjacent first resin 51, and a part of the constituent resin peels off, resulting in a state in which it is completely separated from the adjacent resin (see Figures 8(C) and (D)). (vi) A configuration in which two or more of the above forms (i) to (v) are combined.

[0044] As a result, the divided portion 53 contains one or more subdivided fibers 55 having a fiber diameter smaller than the fiber diameter in the undivided portion 54 (see Figure 7). The subdivided fibers 55 consist of the first resin 51 and the second resin 52 that constitute the divided composite fiber 5. In embodiments (i) to (iii), subdivided fibers 55 consisting of the first resin 51 or the second resin 52 are formed. In embodiments (iv) and (v), subdivided fibers 55 are formed that include the first resin 51 and the second resin 52 and have a fiber diameter smaller than the undivided divided composite fiber 5. This embodiment also includes embodiments in which adjacent resins in the subdivided fibers 55 are not completely separated, as shown in Figures 8(B) to (D).

[0045] These subdivided fibers 55 become parts that enhance mobility within the three-dimensional network structure of the fibers formed by the fiber fusion portion 7. This further enhances the soft elasticity of the nonwoven fabric 10 when subjected to minute loads. It also contributes to the smooth feel of the nonwoven fabric surface and the plump, highly flexible nature of the nonwoven fabric 10.

[0046] On the other hand, the non-divided portion 54 is formed such that all the resins constituting the divided composite fiber 5 are not completely separated. Specifically, as shown in Figures 9(A) to (C), when focusing on one non-divided portion 54, the non-divided portion 54 is composed of one of the following embodiments (a) to (e). These embodiments may be the same or different in each non-divided portion 54. Note that resins that are partially separated in the non-divided portion 54 are not included in the subdivided fiber 55 in this invention. (a) A configuration in which the first resin 51 and the second resin 52 adjacent to the first resin 51 are in contact with each other and no gap is formed (see Figure 9(A)). (i) A configuration in which the first resin 51 and the second resin 52 adjacent to the first resin 51 are in contact with each other, but a portion of the first resin 51 is separated from the adjacent second resin 52, forming a gap S (see Figure 9(B)). (c) A configuration in which the first resin 51 and the second resin 52 adjacent to the first resin 51 are in contact with each other, but a portion of the second resin 52 is separated from the adjacent first resin 51, forming a void S (see Figure 9(B)). (e) The cross-sectional contour of the non-divided portion 54 is elliptical or otherwise non-circular, and adjacent resins 51 and 52 are in contact with each other, but adjacent resins 51 and 52 are partially separated to form a gap S (see Figure 9(C)). (e) A configuration in which two or more of the above forms (a) to (d) are mixed.

[0047] The undivided portions 54 include those having an isotropic cross-section as shown in Figure 9(A) and those having an anisotropic cross-section, such as when the fibers are flattened, as shown in Figure 9(C). Preferably, there are more undivided portions 54 with an anisotropic cross-section, such as when the fibers are flattened, than those with an isotropic cross-section. In either case, the fiber diameter of the undivided portions 54 is equal to or greater than the fiber diameter of the undivided divided composite fiber 5.

[0048] The non-divided portion 54 preferably has a void S formed by a partial separation between the resins 51 and 52, as shown in Figures 9(B) and (C). The void S is preferably formed along the fiber length direction. Such a void S can be formed, for example, in the manufacturing method described later, by appropriately adjusting the degree to which the female support material 130 is pressed into the male support material 120. It is preferable that such voids S are also formed in the undivided segmented composite fiber 5. When such voids S are included in the undivided portion 54 and the undivided divided composite fiber 5, the mobility of the fibers within the three-dimensional network structure of the nonwoven fabric 10 is further enhanced. This further enhances the aforementioned soft elasticity.

[0049] In the divided composite fiber 5 having divided portions 53 and non-divided portions 54 as described above, the aforementioned fiber intersection fusion portion 71 may be located in either the subdivided fibers 55 in the divided portion 53 or the non-divided portion 54. It is preferable that the fiber intersection fusion portion 71 be located in the subdivided fibers 55, as this further enhances the soft elasticity of the nonwoven fabric. Furthermore, it is possible to prevent fuzzing and shedding of fibers in the nonwoven fabric 10, thereby improving the feel of the nonwoven fabric 10. The presence or absence of fiber intersection fusion portions 71 in the divided composite fiber 5 can be determined by the same method as described above (method for confirming fiber fusion portions 7). Furthermore, by observing the divided composite fiber 5 in the divided state using the same method, areas where the resins are not completely separated can be identified as non-divided portions 54.

[0050] In the segmented composite fiber 5, the segmented portion 53 and the non-segmented portion 54 are arranged alternately along the longitudinal direction of the fiber. This structure allows for both a pleasant feel due to the subdivided fibers 55 present in the segmented portion 53 and flexibility due to the moderate resistance to external forces provided by the non-segmented portion 54. As a result, the nonwoven fabric 10 exhibits a smoother surface and a softer, more pliable flexibility compared to a nonwoven fabric composed solely of fine-diameter fibers.

[0051] In the segmented composite fiber 5, the ratio of segmented fibers having segmented portions 53 and non-segmented portions 54 is preferably 3% or more, more preferably 5% or more, and even more preferably 10% or more, as a ratio to the total number of segmented composite fibers 5 in the nonwoven fabric 10, from the viewpoint of achieving a good texture. Furthermore, from the viewpoint of obtaining sufficient nonwoven fabric strength, this ratio is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less.

[0052] (Method for measuring the ratio of the number of divided pieces having divided sections 53 and undivided sections 54) First, the nonwoven fabric to be measured is frozen with liquid nitrogen to fix the state of the fibers. A 4mm square area is cut from the top of the nonwoven fabric, extending across its entire thickness, to serve as the measurement sample. The focus is set on the outermost layer of fibers on the imaging surface of the measurement sample. Samples are taken from three different locations on the measurement sample and imaged at 500x magnification using an electron microscope (JCM-6000Plus (product name), manufactured by JEOL Ltd.), obtaining 10 electron microscope images from each location, for a total of 30 images. From the images, areas where the resins are not completely separated are identified visually as non-divided areas 54, and the number of fibers including non-divided areas 54 and the number of fibers excluding non-divided areas 54 (including divided fibers and normal fibers) are counted. The number of fibers to be counted should be 60 or more (since there is a limit to the number of fibers that can be counted from 30 images, many measurement samples are used to count so that the total is 60 or more).

[0053] From the viewpoint of obtaining a good texture for the nonwoven fabric, the fiber diameter of the undivided divided composite fiber 5 is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 18 μm or less. Furthermore, from the viewpoint of obtaining a high-quality web, the fiber diameter of the undivided divided composite fiber 5 is preferably 8 μm or more, more preferably 10 μm or more, and even more preferably 12 μm or more.

[0054] The subdivided fibers 55, made of the first resin 51 or the second resin 52, have a smaller fiber diameter than the undivided segmented composite fibers 5, and their cross-section is not perfectly circular. In particular, the subdivided fibers 55 made of the second resin 52 do not melt when the fiber intersection fusion portion 71 is formed, maintaining their fiber shape and having a constant fiber diameter. The fiber diameter of the subdivided fibers 55 made of the second resin 52 is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less, from the viewpoint of further enhancing the soft elasticity and other properties of the nonwoven fabric 10. Furthermore, the fiber diameter of the subdivided fibers 55 made of the second resin 52 is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more, from the viewpoint of obtaining sufficient nonwoven fabric strength.

[0055] It is preferable that the fiber diameter of the undivided portion 54 be within the same range as the fiber diameter of the undivided divided composite fiber 5.

[0056] Furthermore, if the nonwoven fabric 10 contains other fibers 8 in addition to the segmented composite fibers 5, the fiber diameter of the fibers 8 is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. Also, the fiber diameter of the fibers 8 is preferably 6 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more.

[0057] (Method for measuring fiber diameter) Three of these measurement samples are prepared by cutting out a rectangular area from the nonwoven fabric to be measured, measuring 4 mm vertically and 7 mm horizontally from wall 1B, along the entire thickness. The surface of each measurement sample is imaged at 1000x magnification using an electron microscope (JCM-6000Plus (product name), manufactured by JEOL Ltd.). In the electron microscope imaging described above, the focus is set on the outermost layer of fibers on the imaging surface of the measurement sample. For each measurement sample, 10 different locations are photographed, and a total of 30 electron microscope images are obtained for three measurement samples. Then, using the electron microscope observation software (JCM-6000Plus (product name) Ver. 1.6.) (using the software's length measurement command), all fibers whose fiber cross-sections can be seen are visually identified from the captured images, and segmented composite fibers and other fibers are visually distinguished, and the diameter of each fiber is measured. At least 30 fibers each of segmented composite fibers and other fibers are measured. The average fiber diameter of segmented composite fibers and other fibers is taken as the respective fiber diameter.

[0058] The nonwoven fabric 10 has improved thickness retention due to the above structure, and has a density of 4.9 mN / cm². 2 (0.05 gf / cm 2 The thickness under load is preferably 1.0 mm or more, more preferably 1.2 mm or more, and even more preferably 1.5 mm or more. This thickness corresponds to 4.9 mN / cm². 2 (0.05 gf / cm 2 ) It can be measured using a laser displacement meter or the like under load. (The above 4.9 mN / cm) 2 (0.05 gf / cm 2 The load is a load that assumes fuzzing of the nonwoven fabric surface. (4.9 mN / cm² for nonwoven fabric 10) 2 (0.05 gf / cm 2 ) By keeping the thickness under load within the above range, the liquid return prevention performance is enhanced, making it less likely for the wearer's skin to get wet. Furthermore, the nonwoven fabric 10 has a load of 4.9 mN / cm². 2 (0.05 gf / cm 2 The thickness under load is preferably 10 mm or less, more preferably 7 mm or less, and even more preferably 5 mm or less, from the viewpoint of not hindering the wearer's comfortable use.

[0059] The basis weight of nonwoven fabric 10 is 8 g / m², from the perspective of obtaining sufficient nonwoven fabric strength. 2 The above is preferable, 10 g / m 2The above is more preferable: 15 g / m 2 The above is even more preferable. Furthermore, the basis weight of the nonwoven fabric 10 should be 80 g / m², from the viewpoint of not hindering the wearer's comfortable feel. 2 The following is preferable: 50 g / m 2 The following is more preferable: 40g / m 2 The following is even more preferable.

[0060] Next, a more preferred embodiment of the aforementioned uneven structure in the nonwoven fabric 10 of this embodiment will be described.

[0061] In the nonwoven fabric 10, it is preferable that the wall portion 1B has a shape that extends perpendicularly to the bottom portion 2. This means that the wall portion 1B has a shape that extends perpendicularly to the planar direction of the nonwoven fabric 10. As a result, the wall portion 1B vertically connects the top portion 1A and the bottom portion 2, reinforcing the aforementioned effect due to the longitudinal orientation of the fibers. That is, the soft fiber layer of the top portion 1A is more likely to remain supported by the elastic fiber layer of the wall portion 1B. The thickness of the fiber layer of the convex portion 1 can be felt through this top portion 1A, making it easier to obtain a softer tactile sensation. More specifically, this soft tactile sensation is felt as a gentle, reassuring thickness under light pressure, and under further pressure, the convex portion 1 deforms but does not easily sag, and is felt as an elastic, soft thickness. Due to this excellent cushioning, the texture of the uneven structure described above is further improved.

[0062] The "perpendicularity" of the wall portion 1B means not only that the angle θ with respect to the plane of the other side 10B of the bottom portion 2 shown in Figure 1 is exactly 90°, but also that it is between 60° and 120°. Being within this range, the wall portion 1B has a shape that extends at an angle that is substantially recognized as 90° in the thickness direction of the nonwoven fabric 10. The angle θ refers to the intersection angle between the plane tangent to the surface of the other side 10B of the nonwoven fabric 10 and the wall portion 1B. Specifically, as shown in Figure 1, in a cross-section in the thickness direction including the convex portion 1 and the concave portion 2, it refers to the interior angle of the angle formed by the center line M of the width of the fiber layer of the wall portion 1B and the straight line L connecting the lower surfaces of adjacent bottom portions 2. This angle θ can be determined by observing a microscopic image of the cross-section obtained by the aforementioned microscope.

[0063] In the example shown in Figure 1, the wall portion 1B extends linearly between the top portion 1A and the bottom portion 2, and the entire wall portion 1B is erected perpendicular to the bottom portion 2. However, the configuration is not limited to this, and the wall portion 1B may include a portion that extends in a curved or wavy manner between the top portion 1A and the bottom portion 2. In this case, the center line M is defined as the line connecting the boundary point between the top portion 1A and the wall portion 1B and the boundary point between the bottom portion 2 and the wall portion 1B, and the angle θ is determined accordingly. Furthermore, while it is preferable that all of the multiple wall portions 1B extend perpendicularly to the bottom portion 2, some of the wall portions 1B may not extend perpendicularly to the bottom portion 2. In the latter case, from the viewpoint of further enhancing the effect of longitudinal orientation of fibers in the nonwoven fabric 10, it is preferable that the number of wall portions 1B that are perpendicular to the bottom portion 2 be 60% or more of the wall portions 1B in the entire set of multiple protrusions 1.

[0064] In addition, it is preferable that the nonwoven fabric 10 has a hollow region 1C on the other side 10B of the protrusion 1. The hollow region 1C is a space that is not substantially filled with fibers of the nonwoven fabric 10. Specifically, the fiber density determined by the method described later is 10 fibers / mm². 2 This means less than [a certain value]. A lower fiber density in the hollow region 1C is preferable.

[0065] (Method for measuring fiber density) The fiber density can be measured by observing a cross-section of the nonwoven fabric 10 using the following method. The nonwoven fabric 10 is cut in the thickness direction so as to pass through the area to be measured (for example, between wall sections 1B). The cut surface is magnified and observed using a scanning electron microscope (JEOL Ltd. JCM-6000Plus (product name)), and the number of cut fiber cross-sections within a certain area of ​​the cut surface is counted. The magnification is adjusted to a level (150x to 500x) that allows for the measurement of approximately 30 to 60 fiber cross-sections. Next, 1 mm 2 Convert this to the number of fiber cross-sections per unit area, and use this as the fiber density (fibers / mm²). 2 The fiber density of the sample is calculated by averaging the results from the three measurement locations.

[0066] The presence of the hollow region 1C on the other side 10B of the protrusion 1 further enhances the soft feel of the protrusion 1, increasing the aforementioned cushioning properties and resulting in a more pleasant feel of the nonwoven fabric 10. Furthermore, when the nonwoven fabric 10 is used as the surface sheet of an absorbent article, the presence of the hollow region 1C blocks the liquid return path from the absorbent material, thereby improving the ability to prevent liquid return. In addition, the hollow region 1C also serves as a primary storage space in the event of excessive excretion, further reducing the amount of liquid remaining on the skin-contacting side of the surface sheet.

[0067] Next, a specific example of the nonwoven fabric 10 shown in Figure 1 (nonwoven fabric 20) will be described with reference to Figures 10 to 13. The nonwoven fabric 20 has the same configuration as described above for the nonwoven fabric 10, and includes the aforementioned segmented composite fiber 5, and the heat-fusible resin (first resin 51) of the segmented composite fiber 5 includes fiber intersection fusion portions 71 with other fibers. The nonwoven fabric 20 shown in Figure 10 has, in a plan view from one side 20T, a plurality of ridges 11 extending in one direction Y as the aforementioned protrusions 1, and spaced apart from each other in a direction X that intersects with direction Y. The other side 20B of the ridges 11 is a hollow region 11C. One direction Y and the direction X intersecting with direction Y can be appropriately set on one side 20T of the nonwoven fabric 20 according to the purpose. For example, it is preferable that one direction Y and the direction X intersecting with direction Y are orthogonal to each other. When the nonwoven fabric 20 is used as a component such as a surface sheet in an absorbent article, it is preferable that one direction Y is the longitudinal direction of the absorbent article and the direction X intersecting with direction Y is the width direction of the absorbent article.

[0068] Multiple ridges 11 have equivalent heights along the direction of extension. "Equivalent" height means that the height measured using a microscope VHX6000 (product name, manufactured by Keyence Corporation) is within the range of 0.8 times to 1.2 times the average measured value.

[0069] Each of the multiple ridges 11 comprises a top portion 11A and a wall portion 11B that supports the top portion 11A. The top portion 11A is a fibrous layer that comes into contact with the wearer's skin in an absorbent article, and the wall portion 11B is a fibrous layer that connects the top portion 11A and the bottom portion 12 in the thickness direction. That is, when the nonwoven fabric 20 is applied to an absorbent article, one side 20T becomes the skin-contacting side, and the other side 20B becomes the non-skin-contacting side. The fibers of the wall portion 11B are oriented vertically as described above. Furthermore, the shape of the wall portion extends perpendicularly to the bottom portion 12, connecting the top portion 11A and the bottom portion 12 perpendicularly. The longitudinal orientation ratio, which indicates the longitudinal orientation of these fibers, can be measured in a cross section perpendicular to the direction in which the ridge portion 11 extends (a cross section in the thickness direction at the position of the R1-R1 line along the direction X intersecting the one direction Y in Figure 10), as shown in Figure 11, based on the method for measuring the longitudinal orientation ratio of fibers in the wall portion 1B described above. Furthermore, the aforementioned angle θ indicating the "perpendicularity" of the wall portion 11B refers to the interior angle of the angle formed by the center line M of the width of the fiber layer of the wall portion 11B and the straight line L connecting the lower surfaces of adjacent bottom portions 12, in a cross section perpendicular to the direction in which the ridge portion 11 extends (a cross section in the thickness direction at the position of the R1-R1 line along the direction X intersecting the one direction Y in Figure 10). This angle θ can be determined by observing the microscopic image of the R1-R1 line cross section obtained by the aforementioned microscope.

[0070] The nonwoven fabric 20 has, as the aforementioned protrusions 1, saddle portions 15 that connect adjacent ridge portions 11, 11, together with the aforementioned ridge portions 11. The saddle portions 15, like the ridge portions 11, protrude from the bottom portion 12 to one side 20T of the nonwoven fabric 20 and are three-dimensional fiber layers erected in the thickness direction of the nonwoven fabric 20. More specifically, the saddle portion 15 comprises a top portion 15A on one side 20T and a wall portion 15B that supports the top portion 15A. The fibers of the wall portion 15B are oriented vertically as described above. The wall portion 15B is also connected to the aforementioned bottom portion 12 and extends perpendicularly to the bottom portion 12. The term "perpendicular" is synonymous with the term "perpendicular" as defined in the aforementioned ridge portions 11. The longitudinal orientation ratio and the "perpendicularity" of the wall portion 15B in the saddle portion 15 can be measured in the same manner as described above for the wall portion 11B, for a cross section perpendicular to the direction of extension of the saddle portion 15 (a cross section in the thickness direction at the position of the R2-R2 line along one direction Y in Figure 10), as shown in Figure 12.

[0071] The above structure makes it difficult for the ridges 11 connected by the saddle portion 15 to come into close proximity, and prevents the ridges 11 from collapsing in one direction due to external forces such as pressing. In other words, the saddle portion 15 supports the ridges 11 from the side, improving the shape retention of the ridges 11. As a result, the thickness of the ridges 11 is more easily retained under load. For example, when the nonwoven fabric 20 is incorporated into an absorbent article as a surface sheet, even with the wearer's body pressure when wearing the absorbent article, the distance between the top portion 11A and the absorbent side of the other side (non-skin contact side) 20B is easily maintained, and liquid backflow to the other side (skin contact side) 20T is further reduced. Furthermore, the presence of the saddle portion 15 creates a damming effect on the excretory fluid between the ridge portions 11, 11, thereby improving the fluid flow prevention on one side (skin contact side) 20T of the nonwoven fabric 20.

[0072] The saddle portion 15 extends in a direction X that intersects with the direction Y from which the ridge portion 11 extends, in a plan view from one side 20T of the nonwoven fabric 20. The direction X from which the saddle portion 15 extends can be various directions as long as it connects adjacent ridge portions 11, and it is preferable that it is a direction perpendicular to the direction Y from which the ridge portion 11 extends. For example, it is preferable that the direction Y from which the ridge portion 11 extends is the longitudinal direction of the absorbent article, and the direction X from which the saddle portion 15 extends, intersecting the aforementioned direction Y, is the width direction of the absorbent article. Hereinafter, the direction Y and the direction X perpendicular to the said direction Y will also be referred to as the extension direction Y of the ridge portion 11 and the extension direction X of the saddle portion 15.

[0073] The saddle portions 15 are arranged in a plan view of one side 20T of the nonwoven fabric 20, in a plurality of band regions 16 that extend parallel to the ridges 11 between the ridges 11. In each band region 16, a plurality of saddle portions 15 are arranged at intervals along the extension direction Y of the parallel ridges 11. The aforementioned bottom portions 12 are located in the portions where the saddle portions 15 are spaced apart. That is, in each band region 16, the saddle portions 15 and the bottom portions 12 (corresponding to bottom portion 2 in Figure 1) are arranged alternately. As a result, the bottom portions 12 are surrounded by the ridges 11 and the saddle portions 15. More specifically, the region surrounded by the plurality of ridges 11 and the plurality of saddle portions 15, which are three-dimensional fiber layers erected in the thickness direction, is a box-shaped or cylindrical recess, and the bottom portions 12 are located at the bottom of the recess. In the example shown in Figure 10, in a plan view from one side 20T of the nonwoven fabric 20, the ridges 11 and saddles 15 are arranged in a grid pattern, and the bottoms 12 are scattered within the grid pattern, forming a grid-like arrangement.

[0074] Although the saddle portion 15 has a three-dimensional fiber structure similar to the ridge portion 11, it is preferable that it has a portion that is lower in height from the bottom portion 12 than the ridge portion 11, as shown in Figures 12 and 13. This reduces the contact area with the skin on one side 20T of the nonwoven fabric 20, maintaining a pleasant feel against the skin, improving breathability, and further suppressing stuffiness between the fabric and the skin. The difference between the height H1 in the thickness direction of the ridge portion 11 and the height H2 in the thickness direction of the saddle portion 15 (H1-H2) is preferably 0.5 mm or more and 7 mm or less from the viewpoint of improving the above effect. The height H1 in the thickness direction of the ridge portion 11 is the distance in the thickness direction from the other side 20B of the bottom portion 12 to the one side 20T of the top portion 11A of the ridge portion 11. The height H2 in the thickness direction of the saddle portion 15 is the distance in the thickness direction from the other side 20B of the bottom portion 12 to the one side 20T of the lowest position of the top portion 15A of the saddle portion 15.

[0075] (Method for measuring the difference between the height in the thickness direction of the ridge portion 11 and the height in the thickness direction of the saddle portion 15) For the nonwoven fabric 20, as shown in Figure 12, a cross-section in the thickness direction along the extension direction of the band region 16 in which the saddle portions 15 are arranged is prepared at the lowest position of the saddle portion 15 (the cross-section in the thickness direction at the position of the R2-R2 line along one direction Y in Figure 10), and the cross-section is placed on a horizontal table so that the other side 10B of the bottom portion 12 is in contact with it. The height H1 from the horizontal table to one side 20T of the top portion 11A of the ridge portion 11 and the height H2 from one side 20T of the top portion 15A of the saddle portion 15 are measured. From these measured values, the difference in height (H1-H2) is calculated. The aforementioned microscope can be used to measure the height from the horizontal table in both cases.

[0076] Furthermore, the saddle portion 15 is more preferably equipped with a hollow region 15C, as shown in Figure 10, from the viewpoint of further promoting drainage of liquid to the other side 20B of the nonwoven fabric 20 when the nonwoven fabric 20 is used as a surface sheet for an absorbent article. The definition and measurement method of this hollow region 15C are the same as those for the hollow region 11C in the ridge portion 11. It is preferable that the hollow region 15C of the saddle portion 15 is in communication with the hollow region 11C of the ridge portion 11. This promotes the diffusion of the excreted liquid on the other side 20B of the nonwoven fabric 20, further suppressing liquid retention on one side 20T. As a result, the amount of liquid remaining on the nonwoven fabric 20 is further reduced, and it becomes possible to further reduce the amount of liquid adhering to the skin.

[0077] Next, preferred embodiments of the method for manufacturing the nonwoven fabric 20 will be described with reference to Figures 14 to 17. The manufacturing method described below can also be applied to the manufacturing method of the nonwoven fabric 10 that encompasses the nonwoven fabric 20. First, as shown in Figure 14(A), the fiber web 110, in which the fibers are not fused at their intersections before being made into a nonwoven fabric, is placed on the support male material 120. Next, as shown in Figures 14(B) and 17, the fiber web 110 is pressed and sandwiched with the support female material 130 to form the shape. The fiber web 110 includes split-type composite fibers 5 in an undivided state before the fiber fusion portion 7 is formed. This fiber web 110 is supplied from a carding machine (not shown) to a predetermined thickness.

[0078] An example of a male support member 120 is shown in Figure 15. In the male support member 120 shown in Figure 15, multiple protrusions 121 are arranged at intervals in one direction (first direction D1) and in a direction perpendicular to it (second direction D2). Multiple rows of protrusions 121A, each consisting of multiple protrusions 121 arranged in the first direction D1, are arranged spaced apart from each other in the second direction D2. The planar shape of the projection 121, as viewed from the top side, is not limited to a rectangle as shown in Figure 15, but can take various forms. For example, it may be circular, elliptical, rhombus, or the like. The recess 125 has a first recess 125A extending in a first direction D1 between rows of protrusions 121A, 121A, and a second recess 125C located between protrusions 121, 121 in row of protrusions 121A. The second recess 125C is connected to the adjacent first recess 125A and extends intermittently in a second direction D2 via the first recess 125A.

[0079] In the male support member 120, multiple protrusions 121 are arranged corresponding to the positions where the bottom portion 12 of the nonwoven fabric 20 is formed. The second recess 125C between the protrusions 121, 121 in the row of protrusions 121A is located where the saddle portion 15 of the nonwoven fabric 20 is formed. That is, the row of protrusions 121A is located where the band region 16 between the ridges 11, 11 in the nonwoven fabric 20. The first recess 125A is located where the ridges 11 in the first fiber layer M1 of the nonwoven fabric 20 are formed. The bottom of each recess 125 is designed to allow hot air to blow through, and for example, multiple holes are provided (not shown).

[0080] As shown in Figure 16, the female support material 130 has multiple protrusions 131 that are continuous in the first direction D1 and are spaced apart in the second direction D2. The spaces between the protrusions 131 are recesses 132 that are continuous in the first direction D1. The projection 131 of the female support member 130 corresponds to the first recess 125A of the male support member 120. The recess 132 of the female support member 130 corresponds to the row of projections 121A of the male support member 120. The bottom of the recess 132 of the female support member 130 has a structure that allows hot air to blow through, and for example, multiple holes are arranged therein (not shown).

[0081] The height of the projection 131 of the female support member 130 is preferably 1 mm or longer in length so that it can be sufficiently inserted between the projections 121 of the male support member 120.

[0082] The first direction D1 and the second direction D2 in the male support material 120 and the female support material 130 are preferably the machine flow direction (MD) and the cross direction (CD) perpendicular to the machine flow direction in the manufacturing process. The machine flow direction and the cross direction in the manufacturing process are preferably corresponding to one direction Y and one direction X intersecting Y in the nonwoven fabric 20, and are preferably corresponding to the longitudinal direction and the cross direction in the absorbent article containing the nonwoven fabric 20. However, the first direction D1 and the second direction D2 are not limited to these.

[0083] In the manufacturing method of the nonwoven fabric 20 shown in Figure 14, the female support material 130 is pressed onto the male support material 120 from above the fiber web 110 placed on the male support material 120 (Figure 14(A)). At this time, the projection 121 of the male support material 120 is inserted into the recess 132 of the female support material 130. The projection 131 of the female support material 130 is inserted into the first recess 125A of the male support material 120 (Figures 14(B) and 17). At the position of the first recess 125A of the male support member 120, the fiber web 110 is pressed and shaped by the projection 131 of the female support member 130. This portion becomes the ridge portion 11 of the nonwoven fabric 20. At this time, the fibers of the fiber web 110 are shaped between the projection 121 of the male support member 120 and the projection 131 of the female support member 130 into a vertically upright shape along the thickness direction. Since the shaped fibers are highly mobile and not fused, they are oriented in the thickness direction. This portion becomes the wall portion 11B of the ridge portion 11 in the nonwoven fabric 20. Meanwhile, at the position of the projection 121 of the male support member 120, the fibers of the fiber web 110 are pushed up to the bottom of the recess 132 of the female support member 130. This portion becomes the bottom 12 of the nonwoven fabric 20. The bottom 12 is shaped to be connected perpendicularly to the aforementioned wall portion 11B. The female support material 130 does not fit into the second recess 125C between the protrusions 121, 121 in the row of protrusions 121A of the male support material 120 because the recess 132 of the female support material 130 corresponds to this recess 132. However, the protrusions 131, 131 of the female support material 130 exert a pressing force on the fibers of the fiber web 110 located in the second recess 125C of the row of protrusions 121A on both sides. Due to this action, the fibers of the fiber web 110 located in the second recess 125C are stretched in the second direction D2 by the protrusions 131, 131 on both sides, pushed in the thickness direction, shaped in the thickness direction, and the orientation of the fibers changes. This portion becomes the saddle portion 15 of the nonwoven fabric 20. The saddle portion 15 has a top portion 15A and a wall portion 15B, and the wall portion 15B is the same as the wall portion 11B of the ridge portion 11. By applying such an external force through pressing to the fiber web 110, the individual resins constituting the undivided divided composite fiber 5 can be separated to form the divided portion 53.

[0084] Next, as shown in Figure 14(B), with the female support material 130 inserted into the male support material 120, the first hot air W1 is blown onto the fiber web 110 from the side of the female support material 130. That is, the first hot air W1 is blown from the side that will become the other side 20B of the nonwoven fabric 20. As a result, the fiber web 110 is fused to the nonwoven fabric 20 to a degree that it can maintain the uneven shape of the nonwoven fabric 20. In the fiber web 110, the fibers are fused to each other very loosely.

[0085] The temperature of the first hot air W1 is set to a temperature at which the thermoplastic fibers can maintain their shape in the thickness direction and the planar direction. Preferably, the temperature is 0°C to 70°C higher than the melting point of the first resin 51 of the segmented composite fibers 5 contained in the fiber web 110, and more preferably 5°C to 50°C higher. From the viewpoint of effective fusion bonding, the wind speed of the first hot air W1 is preferably 2 m / s or more, and more preferably 3 m / s or more. Furthermore, from the viewpoint of making the apparatus compact, the wind speed of the first hot air W1 is preferably 100 m / s or less, and more preferably 80 m / s or less. In this way, the fiber web 110 is temporarily fused and held in an uneven shape.

[0086] The height of the projection 121 on the male support member 120 and the height of the projection 131 on the male support member 130 are appropriately determined depending on the apparent thickness of the nonwoven fabric 20 to be manufactured. For example, 2 mm or more is preferred, 3 mm or more is more preferred, 5 mm or more is even more preferred, 15 mm or less is preferred, 10 mm or less is more preferred, and 9 mm or less is even more preferred. Specifically, 2 mm to 15 mm is preferred, 3 mm to 10 mm is more preferred, and 5 mm to 9 mm is even more preferred.

[0087] Next, the female support material 130 is removed, and as shown in Figure 14(C), a second hot air W2 is blown onto the fiber web 110, which is shaped into an uneven surface, at a temperature that allows the first resin 51 of the segmented composite fibers 5 to fuse appropriately, thereby further fusing the fibers together. In this case as well, similar to the first hot air W1, the second hot air W2 is blown onto the fiber web 110 from the side that will become the other side 20B of the nonwoven fabric 20. The temperature of the second hot air W2 at this time is preferably 0°C to 70°C higher than the melting point of the first resin 51 of the segmented composite fibers 5 contained in the fiber web 110, and more preferably 5°C to 50°C higher. The wind speed of the second hot air W2 depends on the height of the protrusions 121 of the male support material 120, but is preferably 2 m / s or more, and more preferably 3 m / s or more. This ensures sufficient heat transfer to the fibers, causing them to fuse together and ensuring sufficient fixation of the uneven shape. Furthermore, the wind speed of the second hot air W2 is preferably 100 m / s or less, and more preferably 80 m / s or less. This suppresses excessive heat transfer to the fibers, resulting in a good texture for the nonwoven fabric 20. Furthermore, by reducing the surface roughness of the female support material 130, the first step of blowing hot air W1 can be omitted. By reducing the surface roughness, unfused fibers do not adhere to the surface, and the female support material can be removed during the second step of blowing hot air W2. In other words, after fabricating the web, the male and female support materials can be fitted together, the female material can be removed, and the web can be processed with the second hot air W2. This results in a simpler processing method.

[0088] In this manner, the fiber web 110 is shaped and fused to form a nonwoven fabric 20 having fiber intersection fused portions 71 with other fibers in the heat-fusible resin of the segmented composite fiber 5.

[0089] In the above-described method for manufacturing the nonwoven fabric 20, the support female material 130 that forms the fiber web 110 is not limited to having projections 131 continuous in the first direction D1, as shown in Figure 16. For example, the projections 131 may be arranged in a grid pattern, with square-shaped recesses 132 between the grid-like projections 131. In this case, the height of the formed saddle portion 15 becomes higher, and the unevenness becomes more pronounced.

[0090] The nonwoven fabric of the present invention can be used for a variety of purposes. For example, it can be used as a component of various absorbent articles. These various absorbent articles broadly include articles used to absorb bodily fluids, such as adult and infant diapers, sanitary napkins, panty liners, and incontinence pads. The nonwoven fabric of the present invention can also be used as a baby wipe, cleaning sheet, filter, or covering sheet for heating devices.

[0091] An absorbent article having the nonwoven fabric of the present invention typically comprises a surface sheet, a back sheet, and a liquid-retaining absorbent interposed between the two sheets. In the absorbent article, the nonwoven fabric of the present invention can be suitably used as a surface sheet that comes into contact with the wearer's skin. The nonwoven fabric of the present invention can also be used as a sublayer interposed between the surface sheet and the absorbent, or as a covering sheet (core wrap sheet) for the absorbent. In addition, the nonwoven fabric of the present invention can also be used as a surface sheet, gather, outer sheet, or wing of an absorbent article. [Examples]

[0092] The present invention will be described in more detail below based on examples, but the present invention is not to be limited thereto.

[0093] (Example 1) As the raw material fiber for the nonwoven fabric, a segmented composite fiber 5 with a perfectly circular cross-section and a fiber diameter of 14.7 μm was used. The segmented composite fiber 5 used as the raw material fiber was in an unsegmented state, before the formation of the heat-sealed portion. In this segmented composite fiber 5, a PE (melting point: 132°C) resin component, which is the first resin 51 (first heat-sealed resin), and a PET (melting point: 250°C) resin component, which is the second resin 52 (second heat-sealed resin), were continuously arranged in the longitudinal direction of the fiber, and each resin was arranged alternately along the circumferential direction W of the fiber, with each resin being able to be separated. Furthermore, in its cross-section, the segmented composite fiber 5 was divided into a total of 8 sections, with 4 sections each of PE and PET (number of sections: 8), and these resins were arranged radially.

[0094] First, the basis weight is 25.5 g / m². 2 A fiber web 110 consisting only of segmented composite fibers adjusted to achieve the above configuration was formed, and the nonwoven fabric sample of Example 1 shown in Figure 10 was prepared using the manufacturing method shown in Figure 14.

[0095] The male support member 120 used had projections 121 in the pattern shown in Figure 15. The projections 121 were prism-shaped with a height of 10 mm and were 2 mm x 2 mm squares when viewed from above. The pitch of the projections 121 was 5 mm in both the first direction D1 and the second direction D2. The female support material 130 was made of metal and had protrusions 131 in the pattern shown in Figure 16. The protrusions 131 were linear with a width of 2 mm and were arranged at a pitch of 5 mm. The projections 131 of the female support material 130 were pressed between the projections 121 of the male support material 120. The space for the fibers to enter when the female support material 130 was pressed into the male support material 120 was 1 mm on each side. However, the first hot air W1 spraying treatment was not performed when the female support member 130 shown in Figure 14(B) was inserted into the male support member 120, and the second hot air W2 spraying treatment was performed only when the female support member 130 shown in Figure 14(C) was removed from the male support member 120. The second hot air spraying treatment (W2) was performed under conditions of a temperature of 160°C, a wind speed of 1.5 m / s, and a spraying time of 1 s.

[0096] The nonwoven fabric sample obtained in Example 1 had one side 20T designated as the side facing the male support material 120 (the side opposite to the side to which hot air was blown). The basis weight and thickness (4.9 mN / cm²) of the prepared nonwoven fabric sample were as follows: 2 (0.05 gf / cm 2 The results under load were as shown in Table 1. In the nonwoven fabric sample, the fibers in the wall portion 11B were longitudinally oriented with the longitudinal orientation ratio shown in Table 1. Furthermore, in the wall portion 11B, fiber fusion portions (fiber intersection fusion portions) 7 were located at the fiber intersections with other fibers in the PE portion of the first resin 51 (first heat-fusible resin) of the split-type composite fiber 5. In the wall portion 11B, the number ratio of fiber fusion portions 7 including the split-type composite fiber 5, the fusion area of ​​the fiber fusion portions 7, and the number ratio of split-type composite fibers 5 were as shown in Table 1. These were measured using the respective measurement methods described above. Furthermore, the segmented composite fibers 5 contained in the nonwoven fabric sample included those in a segmented state having segmented portions 53 and unsegmented portions 54. In the segmented portion 53, the fiber diameter of the subdivided fibers 55, which consist of the PET resin component, the second resin 52 (second heat-fusible resin), was as shown in Table 1. In addition, the unsegmented portion 54 contained voids S.

[0097] (Examples 2-5) Nonwoven fabric samples for Examples 2 to 5 were prepared in the same manner as in Example 1, except that a fiber web was used which was a mixture of the segmented composite fiber 5 used in Example 1 and a core-sheath composite fiber (fiber diameter 11.7 μm, resin content ratio: core 48.8 mass%, sheath 51.2 mass%) in which the core was made of PET resin and the sheath was made of PE resin. The mixing ratio of segmented composite fiber 5 and core-sheath composite fiber was as shown in Table 1. The basis weight and thickness (4.9 mN / cm²) of each nonwoven fabric sample are shown below. 2 (0.05 gf / cm 2 The results under load were as shown in Table 1. In each nonwoven fabric sample, the fibers in the wall portion 11B were longitudinally oriented with the longitudinal orientation ratio shown in Table 1. Furthermore, in the wall portion 11B, fiber fusion portions (fiber intersection fusion portions) 7 were located at the fiber intersections with other fibers in the PE portion of the first resin 51 (first heat-fusible resin) of the split-type composite fiber 5. In the wall portion 1B, the number ratio of fiber fusion portions 7 including the split-type composite fiber 5, the fusion area of ​​the fiber fusion portions 7, and the number ratio of split-type composite fibers 5 were as shown in Table 1. These were measured using the measurement methods described above. Furthermore, the segmented composite fibers 5 contained in the nonwoven fabric sample included those in a segmented state having segmented portions 53 and unsegmented portions 54. In the segmented portion 53, the fiber diameter of the subdivided fibers 55, which consist of the PET resin component, the second resin 52 (second heat-fusible resin), was as shown in Table 1. In addition, the unsegmented portion 54 contained voids S.

[0098] (Comparative example) A comparative nonwoven fabric sample was prepared in the same manner as in Example 1, except that only the core-sheath composite fiber used in Example 2 was used, and no split-type composite fiber 5 was used. Basis weight and thickness (4.9 mN / cm²) of the nonwoven fabric sample. 2 (0.05 gf / cm 2 The results under load were as shown in Table 1. In the nonwoven fabric sample, the fibers in the wall portion 11B were longitudinally oriented with the longitudinal orientation ratio shown in Table 1. In the wall portion 11B, there were no fiber fusion portions 7 at the fiber intersections between the divided composite fibers 5 and other fibers, and the area ratio of the fiber fusion portions 7 was as shown in Table 1. These were measured using the measurement methods described above.

[0099] [Compressive deformation characteristics under small loads] The measurements were taken based on the aforementioned (method for measuring compression characteristics under minute loads).

[0100] [Cushioning evaluation] For each example and comparative example of nonwoven fabric samples, three panelists (adult men and women) were asked to evaluate the cushioning feel of the samples. This evaluation of texture was done on a scale of 5 points (highest rating: 5 points, lowest rating: 1 point). The results (average scores of the three panelists for texture) are shown in Table 1 below.

[0101] [Wet bag quantity] (1) Measurement conditions Evaluation samples: Nonwoven fabric samples of each example and comparative example prepared to 100 mm x 80 mm. Absorbent material: The absorbent material contained in Japanese-made "Merries M size" (manufactured by Kao Corporation) Evaluation solution: Artificial urine Artificial urine injection location: 155 mm from the front end of the absorbent material, and in the width direction, the center of the absorbent material. Injection amount: 40g x 4 times (injection interval 10min) Injection method: Inject using a metered pump (inject for 8 seconds at a setting of 5g / sec). Pre-pressurization: None Mangle pressurization: 1 pass-through (The evaluation sample was placed between two 3mm thick acrylic plates. The pressure was adjusted so that the scale read 0.2 (85mm) with the evaluation sample in place (the mangle was set with the movable spiral part open 70mm)). Pressurized weight: 1.5kg Pressure plate, acrylic sheet (70mm x 70mm x 3mm) Liquid-absorbing collagen film (70mm x 70mm) 10 sheets (2)Measurement method A 70mm x 70mm rectangle was drawn and marked with the artificial urine injection site on the absorbent material (using a pressure plate). The evaluation sample was cut to 70mm x 70mm, placed on the absorbent material so as to overlap with the drawn rectangle, and pressure was applied using a mangle. A tube for artificial urine infusion was placed 10 mm above the center point, and 40 g of artificial urine was injected. The tube was then left to stand for 10 minutes. This injection and standing process was repeated three times. After the final standing period, the mass was measured. Next, collagen films (10 sheets) were placed on the evaluation sample. A pressure plate and a weight (1.5 kg) were placed on top of the collagen films, and pressure was applied for 30 seconds. After 30 seconds, the weights and pressure plates were removed and the mass of the collagen film was measured. The difference between the mass of the collagen film after pressurization and the mass of the collagen film before pressurization was defined as the wet bag value.

[0102] [Table 1]

[0103] As shown in Table 1, the nonwoven fabric samples of each example had compression deformation characteristics values ​​at a minute load that were 1.3 times higher than those of the comparative example's nonwoven fabric samples, exhibiting a soft elasticity that easily deforms under small loads, and demonstrating superiority in terms of the cushioning sensation perceived by humans. In fact, the cushioning sensation evaluation values ​​for the nonwoven fabric samples of each example were 2.3 times higher than those of the comparative example's nonwoven fabric samples, and they were evaluated as having excellent cushioning sensation. At the same time, the nonwoven fabric samples of each example showed less wet backing compared to the nonwoven fabric samples of the comparative example. This is because the nonwoven fabric samples of each example maintained their thickness better than the nonwoven fabric samples of the comparative example, even under a heavy load of 1.5 kg. As described above, the nonwoven fabric samples in each embodiment were able to achieve both thickness retention and soft elasticity when subjected to minute loads such as those applied by stroking with the palm or fingertips, thereby reducing the amount of liquid that had to be wetted. [Explanation of symbols]

[0104] 1. Convex part 1A Top 1B Wall section 1C hollow area 2 bottom 5-part composite fiber 51. First resin (first heat-sealable resin) 52. Second resin (second heat-fusible resin) 53 Split part 54 Undivided part 55. Subdivided fibers 6 Fiber intersections 61 Fiber intersections between segmented composite fibers 62-part composite fibers and other types of fibers 7. Fiber fusion section 71 Fiber intersection fusion section (a fiber fusion section located at the fiber intersection of a split-type composite fiber, where the first resin, which is a heat-fusible resin, meets other fibers (other split-type composite fibers or other types of fibers)). 72 Fiber fusion section (at the fiber intersection of other types of fibers, other than split composite fibers) 8. Other types of fibers (other types of fibers different from split composite fibers) 81 Fiber intersections between other types of fibers, other than the split-type composite fiber 5 11 Ridge 11A Top 11B Wall section 11C Hollow area 12 Bottom 15. Saddle 15A top 15B Wall section 15C hollow area 16 band regions 10, 20 Nonwoven fabric 10T, 20T, one side 10B, 20B Other side W Circumferential direction

Claims

1. A nonwoven fabric having a bumpy structure with multiple protrusions and bottoms provided between adjacent protrusions, and having fiber fusion portions, Each of the aforementioned multiple protrusions comprises a top portion and a wall portion that supports the top portion, and the fibers of the wall portion are oriented longitudinally. The constituent fibers of the aforementioned uneven structure include a segmented composite fiber in which two or more resins with different melting points are continuously arranged in the longitudinal direction of the fiber as constituent components, and each resin is arranged alternately along the circumferential direction of the fiber, and the spaces between each resin are made separable. The aforementioned segmented composite fiber includes a fiber that alternately comprises segmented portions, where at least one pair of adjacent resins are completely separated, and non-segmented portions, where all adjacent resins are not completely separated, along the longitudinal direction of the fiber. A nonwoven fabric in which the resins arranged alternately along the circumferential direction of the divided composite fibers include a first heat-fusible resin and a second heat-fusible resin having a higher melting point than the first heat-fusible resin, and the fiber fusion portions are arranged at the fiber intersections between the first heat-fusible resin and other fibers.

2. The nonwoven fabric according to claim 1, wherein the proportion of fiber fused portions containing the divided composite fibers among the fiber fused portions included in the wall portion is 10% or more.

3. The nonwoven fabric according to claim 1, wherein the proportion of the number of divided composite fibers among the constituent fibers of the wall portion is 15% or more.

4. The nonwoven fabric according to claim 1, wherein the number of resin segments in the cross-section of the segmented composite fiber is 4 or more and 48 or less.

5. The nonwoven fabric according to claim 4, wherein the segmented composite fibers have voids formed by partial separation between each resin.

6. The nonwoven fabric according to claim 5, wherein the divided portion contains subdivided fibers made of the first heat-fusible resin or the second heat-fusible resin, and the fiber diameter of the subdivided fibers made of the second heat-fusible resin is 15 μm or less.

7. 4.9 mN / cm ２ (0.05gf / cm ２ The nonwoven fabric according to claim 1, wherein the thickness under load is 1.0 mm or more and 10.0 mm or less.

8. Basis weight 8 g / m² ２ 80g / m or more ２ The nonwoven fabric according to claim 1, which is as follows:

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

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