Nonwoven fabric for absorbent article

Abstract

To provide a nonwoven fabric for absorbent article, which can achieve liquid permeability capable of dealing with high viscous fluid such as menstrual blood and loose stool.SOLUTION: A nonwoven fabric has one surface side and the other surface side opposite to the one surface side, has two directions in which a vertical direction and a horizontal direction are orthogonal to each other when viewed in a plan view from the one surface side, and includes fiber fused parts at intersection parts between fibers. The nonwoven fabric has a plurality of apexes disposed zigzag along the two directions in plan view from the one surface side, saddle parts that connect between adjacent apexes along a direction intersecting with the two directions, and bottom parts at positions recessed to the other surface side between the adjacent apexes and saddle parts. A wall part continuing in a thickness direction is disposed between the apex and the bottom part and between the saddle part and the bottom part. An aperture penetrating in the thickness direction is disposed on the bottom part. An average fiber orientation degree in the vertical direction is higher at the apex part compared to the saddle part when viewed in plan view from the one surface side of the nonwoven fabric for absorbent article.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a nonwoven fabric for absorbent articles.

Background Art

[0002] Nonwoven fabrics are used in various applications such as components of absorbent articles such as diapers and sanitary napkins. For example, nonwoven fabrics used as the surface sheet of absorbent articles have various structures. For example, Patent Document 1 describes a nonwoven fabric having a concavo-convex structure with a plurality of ridge portions and a bottom portion, and having openings arranged in the bottom portion, as the surface sheet of an absorbent article. Patent Document 2 describes a nonwoven fabric in which a first nonwoven fabric layer and a second nonwoven fabric layer are laminated. The first nonwoven fabric layer has a concavo-convex structure, and the second nonwoven fabric layer has a substantially flat shape. Patent Document 3 describes a nonwoven fabric in which a thinning and melt stabilization portion is formed by a patterned calendar roll, and then the nonwoven fabric is stretched in the CD direction by a gradually increasing elongation roll, and the thinning and melt stabilization portion is ruptured to form holes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the nonwoven fabrics described in Patent Documents 1 and 2, there is no description of partially changing the fiber orientation in the planar direction. Further, in the nonwoven fabric described in Patent Document 3, it has a substantially flat structure by a calendar roll, and furthermore, since the uneven positions of the incremental elongation roller and the positions of the holes do not necessarily coincide, it is difficult to provide an opening at the bottom of the nonwoven fabric.

[0005] When a nonwoven fabric having an opening at the bottom of the concavo-convex structure is used as the surface sheet of an absorbent article, the liquid absorbency of the absorbent article can be enhanced by the presence of the opening. The liquids absorbed by absorbent articles include those with various properties. Among them, highly viscous body fluids such as menstrual blood and soft stools have lower fluidity than urine, and depending on the amount of liquid, the action of the opening may not be sufficient. Further improvement in liquid permeability is desired so as to be able to cope well with such highly viscous body fluids.

[0006] In view of the above points, the present invention relates to a nonwoven fabric for absorbent articles capable of realizing liquid permeability that can also cope with highly viscous body fluids such as menstrual blood and soft stools.

Means for Solving the Problems

[0007] The present invention provides a nonwoven fabric having one surface side and the other surface side opposite to the one surface side, having two directions in which the longitudinal direction and the lateral direction are orthogonal to each other when viewed in plan from the one surface side, and including fiber fusion parts at the intersection parts of the fibers. When viewed in plan from the one surface side, the nonwoven fabric has a plurality of tops arranged in a staggered manner along the two directions, a saddle part connecting between adjacent tops along a direction intersecting the two directions, and a bottom part located in a recessed position on the other surface side between the adjacent tops and the saddle part. Between the top and the bottom and between the saddle part and the bottom, wall parts continuous in the thickness direction are arranged, and in the bottom, opening parts penetrating in the thickness direction are arranged. When viewed in plan from the one surface side, the average fiber orientation degree in the longitudinal direction of the top is higher than that of the saddle part. The present invention provides a nonwoven fabric for absorbent articles.

[0008] Further, the present invention places an unfused fiber web on a support having a concavo-convex shape with a plurality of protrusions and recesses between the protrusions, and along the recesses, the fiber web is pushed in by a pushing portion of a pushing member to be shaped, and openings are formed at positions corresponding to the protrusions to form a concavo-convex perforated fiber web. A pushing step, after removing the pushing member from the support, blowing a first hot air onto the concavo-convex perforated fiber web to fuse the fibers to obtain a concavo-convex perforated nonwoven fabric, a step of stretching the concavo-convex perforated nonwoven fabric in a direction orthogonal to one direction, and a second step of blowing a second hot air onto the stretched concavo-convex perforated nonwoven fabric to fuse the fibers to obtain a stretched concavo-convex perforated nonwoven fabric. A method for manufacturing a nonwoven fabric for absorbent articles is provided.

Advantages of the Invention

[0009] The nonwoven fabric for absorbent articles of the present invention can achieve a liquid permeability that can also handle highly viscous body fluids such as menstrual blood and soft feces. According to the method for manufacturing the nonwoven fabric for absorbent articles of the present invention, the above nonwoven fabric for absorbent articles of the present invention can be preferably manufactured.

Brief Description of the Drawings

[0010]

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Embodiments for Carrying Out the Invention

[0011] A preferred embodiment of the nonwoven fabric for absorbent articles according to the present invention will be described below with reference to the drawings. In this specification, the nonwoven fabric for absorbent articles may sometimes be simply referred to as a nonwoven fabric. The nonwoven fabric 10 of this embodiment is a nonwoven fabric having fiber fusion parts at the crossing parts of the fibers. For example, an air-through nonwoven fabric in which the fiber fusion parts are formed by the air-through method can be mentioned. Therefore, the nonwoven fabric 10 contains thermoplastic fibers in the constituent fibers.

[0012] As shown in FIGS. 1 to 4, such a nonwoven fabric 10 of the present embodiment has front and back surfaces on one surface side 10T and the other surface side 10B. In the nonwoven fabric 10, it is preferable to use one surface side 10T as the use surface from the viewpoints of improving the texture and the dryness of the skin after liquid absorption. For example, when the nonwoven fabric 10 is used as the surface sheet of an absorbent article, one surface side 10T can be the skin side.

[0013] As shown in FIG. 1, when viewed from one surface side 10T in plan view, the nonwoven fabric 10 has two directions in which the longitudinal direction Y and the lateral direction X are orthogonal to each other, and includes fiber fusion parts at the intersections of the fibers as described above. When viewed from one surface side 10T in plan view, the nonwoven fabric 10 has a plurality of tops 1 arranged in a staggered pattern along the longitudinal direction Y and the lateral direction X, which are the two directions, and a saddle part 5 that connects adjacent tops 1, 1 along a direction J that intersects the longitudinal direction Y and the lateral direction X, which are the two directions, at an arbitrary angle. Further, the nonwoven fabric 10 has a bottom part 2 at a position recessed in the other surface side 10B between the adjacent tops 1, 1 and between the saddle parts 5, 5. Thereby, the nonwoven fabric 10 has a concavo-convex structure in the thickness direction. A wall part 15 continuous in the thickness direction is arranged between the top part 1 and the bottom part 2 and between the saddle part 5 and the bottom part 2, and an opening part 3 penetrating in the thickness direction is arranged in the bottom part 2. It is preferable that all of the bottom part 2 has the opening part 3, but from the viewpoint of allowing high-viscosity body fluid to permeate quickly, the opening part 3 preferably has 5% to 100% per number with respect to the bottom part 2, and more preferably 15% to 100%.

[0014] The wall part 15 is composed of a fiber layer continuous in the thickness direction as described above, and the fiber layer can be partitioned by the following method in the cross section in the thickness direction Z of the nonwoven fabric 10. That is, a nonwoven fabric 10 having a cross-section in the thickness direction including a top portion 1 or a saddle portion 5, a wall portion 15, and a bottom portion 2 is placed on the pedestal of a microscope VHX6000 (trade name, manufactured by Keyence Corporation) with one surface side 10T facing upward. The size of the nonwoven fabric 10 to be observed is such that the top portion 1 includes three pitches in both the longitudinal and transverse directions. The cross-sectional positions of the nonwoven fabric 10 are each cut at their respective positions with sharp scissors or the like as shown in FIGS. 2 to 4. Next, a flat plate (for example, a transparent flat acrylic plate) is placed on the nonwoven fabric and a load of 0.5 gf / cm 2 is applied. In this state, the cross-section in the thickness direction Z described above is observed with the microscope at a magnification of 20 times, and a portion extending from one surface side 10T to the other surface side 10B of the nonwoven fabric is defined as the wall portion 15. Of this wall portion 15, an end portion on one surface side 10T is defined as a starting end portion 15A, and an end portion on the other surface side 10B is defined as an extending end portion 15D.

[0015] On one surface side 10T, the top portion 1 and the saddle portion 5 are composed of the fiber layer of the nonwoven fabric 10 excluding the fiber layer of the starting end portion 15A of the wall portion 15 and constitute the surface of one surface side 10T. On the other surface side 10B, the bottom portion 2 is a portion including the fiber layer of the extending end portion 15D of the wall portion 15. The extending end portion 15D of the wall portion 15 forms the outer peripheral edge of the bottom portion 2. In other words, the bottom portion 2 is surrounded by the extending end portion 15D. An opening portion 3 is disposed in a region surrounded by the extending end portion 15D which is the outer peripheral edge thereof.

[0016] In the example shown in FIG. 1, when viewed from one surface side 10T in plan view, the top portion 1 is located at the center of a region surrounded by the starting end portions 15A of the wall portions 15 extending from four adjacent bottom portions 2, and is a region that draws an ellipse so as to be in contact with the starting end portions 15A of the respective wall portions 15. A region surrounded by two top portions 1 and the starting end portions 15A of two wall portions 15 becomes the saddle portion 5. In FIG. 1, for the purpose of understanding the regions and the arrangement of the top portion 1 and the saddle portion 5, these are shown with pattern patterns arranged, but this does not mean that these pattern patterns exist in the actual nonwoven fabric 10.

[0017] Also, in the example of the cross-section of the nonwoven fabric 10 shown in FIGS. 2 to 4, the wall portion 15 inclines in the thickness direction in a mortar shape and extends to the bottom portion 2 located on the other surface side 10B of the nonwoven fabric 10. As a result, the opening area of the opening portion 3 partitioned by the extending end portion 15D of the wall portion 15 at the bottom portion 2 on the other surface side 10B is smaller than the opening area partitioned by the starting end portion 15A of the wall portion 15 on the one surface side 10T. By inclining the wall portion 15 in a mortar shape in the thickness direction in this way, when the nonwoven fabric 10 absorbs liquid, the opening area on the one surface side 10T becomes large, so that the liquid easily enters, and after the liquid is absorbed, the opening area viewed from the other surface side 10B becomes small, so that the liquid hardly returns, which is preferable.

[0018] The "staggered" arrangement of the top portions 1 means that on one surface side 10T, between rows in which a plurality of top portions 1 are arranged in a row while being spaced apart from each other, at a position between the top portions 1 in one row, the top portion 1 in another adjacent row corresponds to it, and the pitch is shifted. The extending direction of this row, the direction in which the rows are arranged side by side, the interval between the top portions 1, 1, and the degree of pitch shift can be appropriately set within the plane of the one surface side 10T of the nonwoven fabric 10.

[0019] The "longitudinal direction Y and transverse direction X", which are two directions orthogonal to each other, are determined by the arrangement of the top portions 1 forming the above-mentioned staggered arrangement, and can be appropriately set according to the purpose of the nonwoven fabric 10. Typically, when the nonwoven fabric 10 is incorporated into a product, it is preferable that the planar shape of the nonwoven fabric 10 on the product is square, and the longitudinal direction X and the transverse direction X are defined based on its four sides. When the square is rectangular, the direction along the long side among the four sides can be the longitudinal direction Y, and the direction along the short side can be the transverse direction X. When the square is square, the direction along any one of the four sides can be the longitudinal direction Y, and the direction along the other side orthogonal to this can be the transverse direction X. Further, the vertical direction Y and the horizontal direction X are preferably the directions of the nonwoven fabric 10 along the machine flow direction (Machine Direction; MD) and the width direction (Cross Drection; CD) orthogonal to the machine flow direction in the manufacturing process of the nonwoven fabric 10, respectively. In FIG. 1, the direction along the machine flow direction MD in the nonwoven fabric 10 is described as the vertical direction Y, and the direction along the width direction CD orthogonal to the machine flow direction is described as the width direction X. When the nonwoven fabric 10 is used as a component such as a surface sheet in an absorbent article, it is preferable that the vertical direction Y is the longitudinal direction of the absorbent article, and the horizontal direction X orthogonal to the vertical direction Y is the width direction of the absorbent article.

[0020] In the nonwoven fabric 10 shown in FIG. 1, on one surface side 10T, a plurality of rows 17 of the tops 1 arranged at equal intervals along the vertical direction Y are arranged in parallel while being spaced apart at equal intervals in the horizontal direction X. The adjacent rows 17A and 17B of the tops 1 are arranged such that the arrangement pitch of the tops 1 in the other row 17B is shifted by a half pitch with respect to the arrangement pitch of the tops 1 in one row 17A. A plurality of combinations of the rows 17A and 17B of the tops 1 are arranged in the horizontal direction X. As a result, there are a plurality of rows 17 of the tops 1 along the vertical direction Y, and a plurality of rows 18 of the tops 1 along the horizontal direction 18 orthogonal to the row 17. Also for the row 18, a plurality of combinations of the rows 18A and 18B in which the arrangement pitch of the tops 1 is shifted by a half pitch are arranged in the vertical direction Y. One pitch is, for example, the distance in the X direction (pitch in the X direction) between the rows 17A (or between the rows 17B) or the distance in the Y direction (pitch in the Y direction) between the rows 18A (or between the rows 18B). The row 18 penetrates the region between the tops 1 in the row 17. That is, the tops 1 in the row 17 along the vertical direction Y and the tops 1 in the row 18 along the horizontal direction X are not arranged side by side in the horizontal direction X. As a result, the region between the tops 1 in the row 17 along the vertical direction Y and the region between the tops 1 in the row 18 along the horizontal direction X overlap, and share the aforementioned bottom 2. As a result, in each row 17 and each row 18, the tops 1 and the bottoms 2 are alternately arranged. In this way, when viewed in plan from one surface side 10T, the tops 1 are arranged in a staggered pattern along two directions, the vertical direction Y and the horizontal direction X. In the example shown in FIG. 1, due to this staggered arrangement, a plurality of tops 1 are arranged at the intersections of an oblique lattice pattern with respect to the vertical direction Y and the horizontal direction X within the plane of one surface side 10T of the nonwoven fabric 10 (hereinafter, this arrangement is also referred to as an oblique lattice arrangement).

[0021] Furthermore, as described above, when viewed in plan from one surface side 10T, the saddle portions 5 are arranged to connect between adjacent tops 1, 1 along a direction J (hereinafter also referred to as an oblique direction) that intersects the two directions (vertical direction Y and horizontal direction X). The oblique direction J is determined by the arrangement of the rows of tops 1 forming the above-described staggered pattern and can be appropriately set according to the purpose of the nonwoven fabric 10.

[0022] In the nonwoven fabric 10 shown in FIG. 1, the oblique direction J is a direction that intersects the vertical direction Y and the horizontal direction X at an arbitrary angle, and is the directions J1, J2 along the lines drawn by connecting the tops 1 forming the above-described oblique lattice arrangement. The saddle portions 5 connect adjacent tops 1, 1 to form a continuous fiber layer along the oblique direction J (J1, J2). The continuous fiber layer composed of the tops 1 and the saddle portions 5 is arranged in the above-described oblique lattice pattern on one surface side 10T.

[0023] In the arrangement of the above-described tops 1 and saddle portions 5, the bottom 2 is arranged in a region surrounded by a plurality of adjacent tops 1 and saddle portions 5 (four tops 1 and four saddle portions 5 in FIG. 1) arranged along the oblique directions J1 and J2. In other words, as described above, the bottom 2 can also be said to be arranged at a position where the regions between adjacent tops 1, 1 in the column 17 along the vertical direction Y and the regions between adjacent tops 1, 1 in the column 18 along the horizontal direction X overlap. As a result, the bottom 2 is in a region surrounded by the wall portion 15, and in this region, it exists at a position recessed on the other surface side 10B. The above-described opening 3 is arranged at the bottom 2, and when viewed in plan from one surface side 10T, the tops 1 and the opening 3 are alternately arranged in the column 17 of the tops 1 along the vertical direction Y, and the tops 1 and the opening 3 are alternately arranged in the column 18 of the tops 1 along the horizontal direction X.

[0024] "Through - penetration in the thickness direction" in the opening 3 arranged at the bottom 2 means that the portion where the constituent fibers of the fiber layer are not arranged penetrates both surfaces of the non - woven fabric 10 in the thickness direction Z. When the non - woven fabric is viewed in plan, it is assumed that it penetrates a portion of 0.5 mm square or more without fibers. Thereby, the liquid - permeability in the thickness direction Z of the non - woven fabric 10 is enhanced.

[0025] The shape of the bottom 2 when the non - woven fabric 10 is viewed in plan can take any shape such as an ellipse, a diamond shape, a diamond shape with rounded corners, a triangle, etc., due to the protrusion shape of the support used in the manufacturing method described later. It is preferable to use an ellipse or a diamond shape with rounded corners in terms of good appearance.

[0026] The opening 3 is a hole formed by processing the fiber layer of the non - woven fabric 10, different from the fine pore diameters formed between the fibers, and has a pore area much larger than the fine pore diameters formed between the fibers. In FIGS. 1 - 4, it is shown that the entire bottom 2 except for the extended end portion 15D is the opening 3, but the size of the opening 3 can be appropriately selected according to the width of the bottom 2, etc. At least 1.0 mm 2 It is preferable to have the above - mentioned pore area. The size of the opening 3 can be measured by placing the non - woven fabric 10 on black cardboard using the above - mentioned microscope. The "opening area" indicating the size of the opening 3 is, when observed by projection from one surface side 10T of the non - woven fabric 10, the contour of the boundary portion where the number of fibers is 20 fibers / mm 2 or less is drawn, and the area surrounded by the contour is taken as the opening area. The "average opening area" is calculated by cutting the non - woven fabric into a 10 cm square and dividing the sum of the opening areas of all the observed opening portions by the number of the opened openings 3. In addition, when another non - woven fabric is laminated on the non - woven fabric 10, if it is joined by hot melt, it is peeled off using a cold spray, etc. Also, if it is heat - sealed and joined, the non - woven fabric 10 is peeled off while pulling at an appropriate angle so as to minimize the damage. In addition, the "average aperture area ratio" is calculated by dividing the total aperture area of all observed apertures on the non-woven fabric placed on the aforementioned black base paper by the area of the non-woven fabric. The "average aperture area of the one surface side 10T" partitioned by the start end portion 15A of the wall portion 15 on the one surface side 10T is measured as the area inside the aperture side of the inflection point of the start end portion 15A when observed in the same manner as the measurement of the "aperture area" described above. Also, the "average aperture area of the other surface side 10B" of the aperture portion 3 partitioned by the extension end portion 15D of the wall portion 15 at the bottom portion 2 of the other surface side 10B is measured as the area from the aperture portion side end portion of the extension end portion 15D to the inside of the aperture side when projected and observed from the other surface side 10B in the same manner. The "average aperture area ratio of the one surface side 10T" and the "average aperture area ratio of the other surface side 10B" are also obtained in the same manner as the above-mentioned "average aperture area ratio".

[0027] From the viewpoint of enhancing the liquid permeability effect, the area of the aperture portion 3 is preferably 1.0 mm 2 or more, more preferably 1.5 mm 2 or more, and still more preferably 2.0 mm 2 or more. Also, from the viewpoint of suppressing liquid return, the area of the aperture portion 3 is preferably 50 mm 2 or less, more preferably 40 mm 2 or less, still more preferably 30 mm 2 or less, and even more preferably 20 mm 2 or less, still more preferably 10 mm 2 or less, and even more preferably 6 mm 2 or less.

[0028] When the non-woven fabric 10 is viewed in plan view, the shape of the aperture portion 3 located inside the bottom portion 2 can be various endless shapes from the viewpoint of enhancing liquid permeability, and examples include a circular shape, an elliptical shape, a rectangular shape, etc. It is preferably similar to the bottom portion 2, and from the reason of enhancing liquid permeability, it is preferably an elliptical shape or a diamond shape with rounded corners. In the example shown below, the aperture portion 3 is shown as having an elliptical planar shape, but it is not limited thereto.

[0029] The outer shape of one surface side 10T of the top part 1 and the saddle part 5 may be a flat surface or a curved surface. From the viewpoint of enhancing the pressure resistance of the thickness against the pressing by the top part 1 and the saddle part 5 while giving a soft touch to the skin by the fiber layer, it is preferable that one surface side 10T of the top part 1 and the saddle part 5 is a flat surface.

[0030] In addition, when viewed in plan from one surface side 10T, the top part 1 has a higher average fiber orientation degree in the longitudinal direction Y than the saddle part 5. Thereby, when liquid reception occurs on one surface side 10T of the nonwoven fabric 10, the liquid absorbed by the top part 1 first diffuses in the longitudinal direction Y, and then diffuses along the fiber orientation to the saddle part 5, and more liquid descends along the wall part 15 to the bottom part 2 and can be quickly drained from the opening part 3 to the other surface side 10B. In particular, in the nonwoven fabric 10, even if the liquid is a highly viscous body fluid with low fluidity such as menstrual blood or soft feces, the highly viscous body fluid can be strongly drawn around the opening part 3, and the liquid permeability can be enhanced in cooperation with the wall part 15 and the opening part 3. That is, the nonwoven fabric 10 can realize a liquid permeability capable of coping with highly viscous body fluids such as menstrual blood and soft feces. The orientation degree ratio of the top part 1 to the saddle part 5 (average fiber orientation degree in the longitudinal direction Y of the top part 1 / average fiber orientation degree in the longitudinal direction of the saddle part 5) is 1.05 times or more and 1.8 times or less, more preferably 1.2 times or more and 1.5 times or less, from the viewpoint of enhancing the diffusibility of the liquid in the top part 1 and enhancing the diffusibility of the liquid in the saddle part 5. It is preferable that the fibers of the top part 1 are oriented in the longitudinal direction Y, and it is preferable that the fibers of the saddle part 5 are oriented in the diagonal direction (J direction). For this reason, the average fiber orientation degree in the longitudinal direction Y of the top part 1 is preferably 1.0 or more and 1.6 or less, and more preferably 1.1 or more and 1.4 or less. For the same reason, the average fiber orientation degree in the longitudinal direction Y of the saddle part 5 is preferably 0.7 or more and 1.0 or less, and more preferably 0.8 or more and 0.95 or less. Thereby, from the viewpoint of making the diffusibility of the above liquid more reliable, it is preferable that the fibers of the saddle part 5 are oriented along the diagonal direction (J direction) which is a direction intersecting the two directions (longitudinal direction Y and transverse direction X) (for example, arrow F in FIG. 1).

[0031] Generally, it is not easy to partially change the fiber orientation degree in the plane direction, but it has become possible to control it by the manufacturing method according to the present invention described later. As a result, for the first time, the configuration of the average fiber orientation degree in the longitudinal direction Y of the above-mentioned top portion 1 and saddle portion 5 has been realized. In the manufacturing method according to the nonwoven fabric of the present invention described later, the following two features are provided to perform the stretching step, enabling the configuration of the average fiber orientation degree in the longitudinal direction Y described above. The first point is that the fusion point of the fibers is not a surface like an emboss as seen in spunbond, but a fusion point is formed at the intersection of the fibers as seen in air-through or resin bond, so that the fibers can be stretched without relatively destroying the fusion point (high deformability). The second point is that since the opening portion 3 is not formed by cutting the fibers but by separating the fibers, the wall portion 15 forms the outer edge of the opening portion 3, making it difficult for the nonwoven fabric to be destroyed during stretching, and it is easy to obtain a nonwoven fabric that is uniformly stretched and has uniform opening sizes. On the other hand, conventionally, there are some nonwoven fabrics with openings without stretching, such as spunlace nonwoven fabrics. However, since the nonwoven fabric is formed by entanglement of the fibers and there is no fusion point of the fibers, when stretched, slippage between the fibers occurs and it is difficult to uniformly stretch and deform. That is, it is difficult to partially change the fiber orientation. However, in the manufacturing method according to the nonwoven fabric of the present invention described later, as described above, during stretching, the shape of the opening is deformed and the fibers around the opening are rearranged. At this time, the fibers in the saddle portion 5 are oriented in an oblique direction along the opening edge (in the J direction in FIG. 1 when viewed in plan), and since the top portion 1 has the opening portions 3 on both sides in the stretching direction, it is difficult for an elongation force to be applied to the top portion 1 and it is difficult to be deformed by elongation. As a result, the fiber orientation of the top portion 1 is likely to be maintained in the longitudinal direction Y. As described above, the configuration of the average fiber orientation degree of the above-mentioned top portion 1 and saddle portion 5 is realized. At this time, it is preferable to increase the area of the top portion 1 because the fiber orientation of the top portion 1 is more likely to be maintained in the longitudinal direction Y.

[0032] (Method for measuring the average fiber orientation degree in the longitudinal direction Y at the top portion 1 and the saddle portion 5) Cut the non-woven fabric sample into an arbitrary size with scissors or the like. When collecting the non-woven fabric from the absorbent article, for example, cut it out in a state where it is joined to other materials joined to the non-woven fabric. Examples of other materials include sublayers and base papers. Using a laser microscope (VK-X3100 (trade name) manufactured by KEYENCE), observe the non-woven fabric from the surface on one side in a plan view with a 10x lens. Place a slide glass on the non-woven fabric so that it becomes 0.5 g / cm 2 Set the sample so that the longitudinal direction of the non-woven fabric (or MD direction) coincides with the longitudinal direction of the observation photograph. The resolution is standard (1024×768), the measurement quality is high precision, the field of view is 1414×1060 μm, the pitch is 2 μm, and the laser light is selected for the measurement image. Take photos of the fibers from the surface on one side of the non-woven fabric (the lower surface of the slide glass) to a depth of 0.8 mm at each central position of the top 1 and the saddle 5. Take photos at 5 different locations each for the top 1 and the saddle 5. The top 1 and the saddle 5 are performed at the same observation magnification. Trim the obtained image into a square so that it becomes a multiple of 64 pixels (e.g., 512 pixels) using image software (such as Paint 3D), and save the image in bmp format. Using the fiber orientation calculation software FiberOri8s03 (provided by Professor Toshiharu Emma, Graduate School of Agricultural and Life Sciences, The University of Tokyo), obtain the Regression MA with Angle of 0 degrees and 90 degrees. The fiber orientation degree in the longitudinal direction is obtained by the following formula. Fiber orientation degree in the longitudinal direction = Regression MA(0 degrees) / Regression MA(90 degrees). The average value of each 5 points is taken as the average fiber orientation degree in the longitudinal direction Y. The higher the value of the average fiber orientation degree, the more the fibers are oriented in the longitudinal direction.

[0033] The non-woven fabric 10 preferably has the above-described average fiber orientation degree configuration on one surface side 10T, and as shown in FIG. 1, the fiber orientation directions of the top 1 and the saddle 5 meander like the arrow S. Thereby, the pressing force in the thickness direction Z is diffused and dispersed in the plane direction on one surface side 10T. As a result, the non-woven fabric 10 has even higher pressure resistance. Further, it is preferable that the shape of the continuous fiber layer in which the tops 1 and the saddles 5 are arranged alternately meanders like the arrow S. Thereby, even with respect to the pressing force in the planar direction (for example, the longitudinal direction X and the lateral direction Y), the pressing force is diffused and dispersed in the planar direction on one surface side 10T, further enhancing the pressure resistance described above.

[0034] From the viewpoint of further enhancing the liquid drawing property and pressure resistance described above, when viewed in plan from one surface side 10T, it is preferable that the periphery of the bottom portion 2 is surrounded by a plurality of tops 1 and a plurality of saddles 5. Since there are wall portions continuous in the thickness direction between the top portion 1 and the bottom portion 2 and between the saddle portion 5 and the bottom portion 2, liquid can be drawn in from all directions around the bottom portion 2.

[0035] In the nonwoven fabric 10, the angle θ of the wall portion 15 is preferably 60° or more and 120° or less, and more preferably 70° or more and 110° or less, from the viewpoint that the thickness of the entire nonwoven fabric becomes thick and the cushioning property is enhanced. Furthermore, the wall portion 15 preferably extends perpendicular to the planar direction of the nonwoven fabric 10. The planar direction of the nonwoven fabric 10 referred to here means the direction along a plane (for example, a flat pedestal) in contact with the surface of the other surface side 10B of the nonwoven fabric 10 (the same applies hereinafter). Thereby, the soft fiber layers of the tops 1 and the saddles 5 are likely to remain in a state of being vertically supported by the elastic fiber layer of the wall portion 15, and the pressure resistance of the nonwoven fabric 10 is further enhanced. In a state where the wall portion 15 vertically supports the tops 1 and the saddles 5, the thickness of the fiber layer of the nonwoven fabric 10 can be felt through the tops 1 and the saddles 5, and a plump tactile sensation is easily obtained. More specifically, a gentle and reassuring thickness is felt at the tops 1 and the saddles 5 under a light pressing force that can be touched, and even under further pressing, although the uneven structure of the nonwoven fabric 10 deforms, it is difficult to collapse and is felt as an elastic and soft thickness. Due to such excellent cushioning properties, the texture due to the uneven structure described above becomes even better. Furthermore, more liquid strongly drawn in around the opening portions 3 of the tops 1 and the saddles 5 is guided more rapidly to the opening portions 3 of the bottom portion 2 along the vertical wall portion 15 so as to fall. Thereby, the liquid permeability in the nonwoven fabric 10 described above is further enhanced.

[0036] The "vertical" of the wall portion 15 means that not only when the angle θ with respect to the plane of the other surface side 10B of the nonwoven fabric 10 shown in FIG. 5 is exactly 90°, but also when it is 80° or more and 100° or less. By being within this range, the wall portion 15 has a shape that extends at an angle that is substantially recognized as 90° in the thickness direction of the nonwoven fabric 10. The angle θ means the intersection angle between the plane of the other surface side 10B of the nonwoven fabric 10 and the extension line of the wall portion 15. Specifically, as shown in FIG. 5, in the cross section in the thickness direction including the top portion 1 or the saddle portion 5, it means the inner angle of the angle formed by the center line M of the width of the fiber layer of the wall portion 15 and the straight line L in contact with the surface of the other surface side 10B of the nonwoven fabric 10. This angle θ can be obtained by observing the micrograph of the cross section obtained by the aforementioned microscope.

[0037] In the example shown in FIG. 5, the wall portion 15 extends linearly in the cross section in the thickness direction Z of the nonwoven fabric 10, and the entire wall portion 15 stands perpendicular to the other surface side 10B of the nonwoven fabric 10. However, it is not limited to this, and the configuration may include a portion where the wall portion 15 extends in a curved or wavy shape in the thickness direction Z of the nonwoven fabric 10. In this case, a straight line connecting the boundary points between the top portion 1 and the saddle portion 5 and the wall portion 15, and the end portion (extended end portion 15D) of the other surface side 10B of the wall portion 15, and taking the center line M passing through the width center of the fiber layer of the boundary point and the extended end portion 15D as the extending direction of the wall portion 1B, and specifying the above angle θ. In addition, although it is preferable that all of the plurality of wall portions 15 extend perpendicular to the plane of the other surface side 10B, a part of the wall portions 15 may include those that do not extend perpendicular to the plane of the other surface side 10B. In the latter case, the number of the wall portions 15 that are perpendicular is preferably 60% or more and 100% or less of all the wall portions 15 from the viewpoint of further enhancing the pressure resistance of the nonwoven fabric 10.

[0038] In addition, it is preferable that there is a hollow region 1C on the other surface side 10B of the top portion 1 and the saddle portion 5. The hollow region 1C is a space that is substantially not filled with the fibers of the nonwoven fabric 10. The smaller the fiber density in the hollow region 1C, the better.

[0039] Since the hollow region 1C is on the other surface side 10B of the top portion 1 and the saddle portion 5, the soft touch feeling of the top portion 1 and the saddle portion 5 is further improved, the above-mentioned cushioning property is further enhanced, and the texture of the non-woven fabric 10 becomes even better. Further, when the non-woven fabric 10 is a member on the skin surface side rather than the absorber in the absorbent article, for example, a surface sheet, the presence of the hollow region 1C cuts off the liquid return path from the absorber, further enhancing the liquid return prevention property. In addition, the hollow region 1C also serves as a primary storage space when the excretion amount becomes excessive, and can reduce the amount of liquid remaining on the skin contact surface side of the surface sheet.

[0040] From the viewpoint of further enhancing the above effects, as shown in FIGS. 3 and 4, the hollow region 1C is preferably continuous along at least one direction in the plane direction of the non-woven fabric 10. This can be appropriately set according to the size and shape of the bottom portion 2 including the apertures 3, the interval between the bottom portions 2, and the like.

[0041] In the non-woven fabric 10, the heights in the thickness direction Z of the surfaces of the top portion 1 and the saddle portion 5 on the one surface side 10T with respect to the straight line L in contact with the surface of the other surface side 10B of the non-woven fabric 10 may be the same or different. When the top portion 1 is higher than the saddle portion 5, it is preferable in that the skin dryness is enhanced by reducing the area ratio of the surface in contact with the skin of the non-woven fabric. When the heights in the thickness direction of the top portion 1 and the saddle portion 5 on the one surface side 10T surface of the non-woven fabric 10 are the same, it is more preferable in that the area ratio of the surface in contact with the skin of the non-woven fabric 10 becomes appropriate and it becomes difficult to leave liquid on the skin. It is more preferable that the saddle portion 5 is thinner or has the same thickness as the top portion 1 in the thickness direction. In the former case, it is more preferable in terms of having appropriate stretchability, and in the latter case, it is more preferable in terms of having appropriate bending rigidity. Also, it is more preferable that the basis weight of the saddle portion 5 is lower or the same as that of the top portion 1. In the former case, it is preferable in that the number of fusing points decreases and it becomes easier to stretch as the basis weight decreases, and in the latter case, it is more preferable in that the number of fusing points becomes appropriate and it becomes difficult to collapse even when a weight or the like is applied. The "equal" height means that when measuring the height of the top part 1 and the saddle part 5 on the cross-section of the non-woven fabric (the thickness-direction cross-section cut along the line connecting the center of the top part 1 and the center of the saddle part 5) using a microscope VHX900 (trade name, manufactured by Keyence Corporation) under a load of 0.5 gf / cm 2 the difference in height is within the range of -0.3 mm or more and +0.3 mm or less with respect to the measurement average value. In this case, one surface side 10T of the non-woven fabric 10 is substantially aligned and made flush at the thickness H1 of the non-woven fabric 10 except for the bottom part 2. Furthermore, in the non-woven fabric 10, it is preferable that the heights in the thickness direction Z of the surface on the other surface side 10B of the non-woven fabric 10 with respect to the straight line L in contact with the surfaces of the top part 1 and the saddle part 5 are equal. This is more preferable in terms of having appropriate bending rigidity.

[0042] The basis weight of the non-woven fabric 10 is preferably 15 g / m 2 or more from the viewpoint of improving the texture of the non-woven fabric and further enhancing the pressure resistance, more preferably 30 g / m 2 or more, and even more preferably 40 g / m 2 or more. Also, the basis weight of the non-woven fabric 10 is preferably 100 g / m 2 or less, more preferably 90 g / m 2 or less, and even more preferably 85 g / m 2 or less from the viewpoint of not disturbing the comfortable feeling of use for the wearer.

[0043] The thickness H1 of the non-woven fabric 10 means the thickness under a load of 0.5 gf / cm 2 The above load of 0.5 gf / cm 2 is a load assuming the fluffing on the surface of the non-woven fabric and can be said to be in a substantially unloaded state. This thickness can be measured using a laser displacement meter or the like under a load of 0.5 gf / cm 2 The 0.5 gf / cm of the non-woven fabric 10 2 ​The thickness H1 under load is preferably 0.8 mm or more, more preferably 1 mm or more, and even more preferably 1.5 mm or more. When the thickness H1 of the nonwoven fabric 10 is within the above range, the liquid return prevention performance is enhanced, and the skin of the wearer is less likely to get wet. From the viewpoint of not disturbing the comfortable feeling of use of the wearer, the thickness H1 is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 7 mm or less.

[0044] The nonwoven fabric 10 preferably has a sublayer including a fiber fusion part on the other surface side 10B. Thereby, the joining of the surface material and the absorber is facilitated through the sublayer, and it is preferable in that it is possible to prevent the hot melt used for adhesion to the absorber from being exposed on the surface through the opening part. Examples of the form of the sublayer include an air-through nonwoven fabric or an embossed nonwoven fabric composed of a single layer or multiple layers.

[0045] Next, a preferred embodiment of the manufacturing method of the nonwoven fabric 10 will be described with reference to FIGS. 6 to 13. As shown in FIGS. 6(A) and (B), FIGS. 7(A) and (B), and FIG. 8, the manufacturing method of the present embodiment has the following four steps (hereinafter, each step may be referred to as step (I), step (II), step (III), and step (IV)). (I) A non-fused fiber web 100 is placed on a support 120 having an uneven shape with a plurality of protrusions 121 and recesses 125 between the protrusions 121, 121. Along the recess 125, the fiber web 100 is pushed in by the pushing part 131 of the pushing member 130 to be shaped, and openings are made at positions corresponding to the protrusions 121 to form an uneven perforated fiber web 101. Pushing step. (II) After removing the pushing member 130 from the support 120, a first hot air W1 is blown onto the uneven perforated fiber web 101 to fuse the fibers to obtain an uneven perforated nonwoven fabric 102. First fusing step. (III) A step of stretching the uneven perforated nonwoven fabric 102 in a direction orthogonal to one direction. (IV) A second fusing step of spraying a second hot air W2 onto the concavo-convex perforated nonwoven fabric 102A in the stretched state to fuse the fibers together to obtain a stretched concavo-convex perforated nonwoven fabric 103.

[0046] The above fiber web 100 contains thermoplastic fibers. The "fiber web" refers to an aggregate of fibers in which the constituent fibers containing thermoplastic fibers are gently entangled without being fused and fixed, and which does not have the shape-retaining property as a sheet by itself. That is, it is a fiber aggregate before being made into a nonwoven fabric. Therefore, the mobility between the fibers in the fiber web is high, and the deformability of the fiber web in the pushing-in step is high. Such a fiber web 100 is supplied from a carding machine (not shown) so as to have a predetermined thickness. The fiber web 100 may be a single layer or a laminate of multiple layers.

[0047] In step (I), as shown in Fig. 6(A), the fiber web 100 on the support 120 is directly pushed in with mechanical pressure using the pushing member 130. Thereby, a concavo-convex perforated fiber web 101 that becomes the nonwoven fabric 10 is formed. Such shaping can form a wall portion perpendicular to the nonwoven fabric plane as compared with the case of pushing in with a non-mechanical pressure such as wind. Also, in order to increase the concavo-convex height difference of the shaping of the fiber web 100, it is not necessary to increase the pushing force so much, and the fiber web 100 can be gently shaped. Also, the shaping property can be enhanced by suppressing the disturbance of the fibers.

[0048] The support 120 is, for example, drum-shaped and has protrusions 121 on the drum circumferential surface as shown in, for example, FIG. 6(A). On the drum circumferential surface of the support 120, as shown in, for example, FIG. 9, a plurality of protrusions 121 are arranged at intervals in one direction (the first direction D1) and a direction orthogonal thereto (the second direction D2). A plurality of protrusion rows 121A formed by arranging the plurality of protrusions 121 in the first direction D1 are arranged at intervals in the second direction D2. The protrusion 121 has a spire portion 122 at its tip. It is preferable that the tip (spire portion 122) of the protrusion 121 has a curvature radius of 0.5 mm or less in terms of facilitating the formation of the opening portion by further separating the fibers. The opening portion 3 at the bottom 2 of the nonwoven fabric 10 is formed by this spire portion 122. The planar shape of the spire portion 122 of the protrusion 121 as viewed from the side is not limited to a rectangle as shown in FIG. 9 and can be various. For example, as shown in FIGS. 10(A) to (E), it may be circular, elliptical, rhomboidal, polygonal such as triangular or hexagonal, and the like. The recess 125 has a first recess 125A extending in the first direction D1 between the protrusion rows 121A, 121A and a second recess 125C between the protrusions 121, 121 in the protrusion row 121A. The second recess 125C is connected to the adjacent first recess 125A. Also, the adjacent protrusion rows 121A, 12A adjacent to each other via the first recess 125A are arranged in a staggered manner such that the second recess 125C of the other protrusion row 121A corresponds to the second recess 125C between the second recesses 125C of one protrusion row 121A. Thereby, the second recesses 125C extend intermittently in the second direction D2 via the first recess 125A and the protrusion 121.

[0049] In the support 120, a plurality of protrusions 121 are arranged corresponding to the positions where the apertures 3 of the bottom portion 2 in the nonwoven fabric 10 are formed. The second recess 125C between the protrusions 121 in the protrusion row 121A is at the position where the horizontal ridge portion 91 in the concavo-convex apertured nonwoven fabric 102 obtained in the step (II) is shaped. The first recess 125A is at the position where the vertical ridge portion 95 in the concavo-convex apertured nonwoven fabric 102 obtained in the step (II) is shaped. Note that the horizontal ridge portion 91 becomes the top portion 1 on one surface side 10T of the nonwoven fabric 10 through the step (III). The vertical ridge portion 95 is deformed through the step (III), and the deformed portion becomes the saddle portion 5 on one surface side 10T of the nonwoven fabric 10. Details will be described later. The bottom of each recess 125 has a structure through which hot air blows through, for example, a plurality of holes are arranged (not shown).

[0050] The pushing member 130 is, for example, in a roll shape and has a pushing portion 131 as shown in FIG. 6(A) on the roll circumferential surface. On the roll circumferential surface of the pushing member 130, as shown in FIG. 11 for example, a plurality of pushing portions 131 continuous in the first direction D1 are arranged at intervals in the second direction D2. The space between the pushing portions 131 is a recess 132 continuous in the first direction D1. The pushing portion 131 of the pushing member 130 corresponds to the first recess 125A of the support 120. The recess 132 of the pushing member 130 corresponds to the protrusion row 121A of the support 120. The bottom of the recess 132 of the pushing member 130 has a structure through which hot air blows through, for example, a plurality of holes are arranged (not shown).

[0051] The height of the pushing portion 131 of the pushing member 130 preferably has a length of 1 mm or more so as to be sufficiently inserted between the protrusions 121 of the support 120.

[0052] The above-described first direction D1 and second direction D2 in the support 120 and the pushing member 130 are preferably the machine flow direction (MD) and the width direction (CD) orthogonal to the machine flow direction in the manufacturing process. The machine flow direction and the width direction in the manufacturing process preferably correspond to the longitudinal direction Y and the transverse direction X in the nonwoven fabric 10, and preferably correspond to the longitudinal direction and the width direction in the absorbent article including the nonwoven fabric 10 and the nonwoven fabric 10. However, the first direction D1 and the second direction D2 are not limited thereto.

[0053] In step (I), the protrusion 121 of the support 120 is inserted into the recess 132 of the pushing member 130. The pushing portion 131 of the pushing member 130 is inserted into the first recess 125A of the support 120 (FIGS. 6(A) and 12). By the pushing between the support 120 (such as FIGS. 9, 10(A) to (E)) and the pushing member 130 (FIG. 11), the uneven shape of the uneven opening fiber web 101, which is a precursor of the nonwoven fabric 10, can be preferably formed. At the position of the first recess 125A of the support 120, the fiber web 100 is pushed and shaped by the pushing portion 131 of the pushing member 130. This portion becomes the longitudinal ridge portion 95 in the uneven opening nonwoven fabric 102 (FIGS. 6(B) and 7(A)). At this time, between the protrusion 121 of the support 120 and the pushing portion 131 of the pushing member 130, the fibers of the fiber web 100 are shaped into a vertically standing shape along the thickness direction. This portion becomes the wall portion 15 that supports the longitudinal ridge portion 95 in the thickness direction. On the other hand, at the position of the protrusion 121 of the support 120, the fibers of the fiber web 100 are pushed up to the bottom of the recess 132 of the pushing member 130, and the fibers corresponding to the opening portion 3 are separated by the outer peripheral side of the opening portion 3 from the protrusion 121 of the support 120. Thereby, it is opened. This portion becomes the opening portion 3 at the bottom 2 in the uneven opening nonwoven fabric 102. The fibers of the fiber web 100 in the second recess 125C between the protrusions 121 in the protrusion row 121A of the support 120 are shaped in the thickness direction under the action of the pushing forces of the pushing portions 131, 131 of the pushing member 130 on both sides thereof. This portion becomes the horizontal ridge portion 91 in the concavo-convex perforated nonwoven fabric 102. Also, for the horizontal ridge portion 91, a wall portion 15 that supports it in the thickness direction is formed.

[0054] Note that the height of the protrusion 121 of the support 120 and the height of the pushing portion 131 of the pushing member 130 are appropriately determined according to the thickness of the nonwoven fabric to be manufactured, etc. For example, 2 mm or more is preferable, 3 mm or more is more preferable, 5 mm or more is still more preferable, and 15 mm or less is preferable, 10 mm or less is more preferable, 9 mm or less is still more preferable. Specifically, 2 mm or more and 15 mm or less is preferable, 3 mm or more and 10 mm or less is more preferable, 5 mm or more and 9 mm or less is still more preferable.

[0055] Next, in the first fusing step of step (II), after removing the pushing member 130 from the support 120, as shown in FIG. 6(B), the first hot air W1 is blown onto the concavo-convex perforated fiber web 101. The surface side in contact with the support 120 becomes one surface side 10T of the nonwoven fabric. By this blowing, the fibers in the concavo-convex perforated fiber web 101 are fused to form the concavo-convex perforated nonwoven fabric 102. As shown in FIG. 7(A), the concavo-convex perforated nonwoven fabric 102 includes a horizontal ridge portion 91 and a vertical ridge portion 95 on the surface side (one surface side 10T in the nonwoven fabric 10) pushed into the recess 125 of the support 120. In addition, it has a bottom portion 2 provided with an opening portion 3 on the surface side (one surface side 10B in the nonwoven fabric 10) located at the spire portion 122 of the protrusion 121 in the region between the horizontal ridge portions 91, 91. Note that the hot air treatment here performs fusion of the fibers to some extent so that the orientation direction of the fibers can be changed by the stretching treatment in the subsequent step (III).

[0056] The temperature of the first hot air W1 is set to be equal to or higher than the melting point of the constituent fibers of the concavo-convex perforated fiber web 101. Considering the general fiber materials used in this type of product, the temperature of the first hot air W1 is preferably 0°C or higher and 70°C or lower higher than the melting point of the constituent fibers (thermoplastic fibers) of the concavo-convex perforated fiber web 101, and more preferably 5°C or higher and 50°C or lower higher. From the viewpoint of achieving good nonwoven fabric formation, the wind speed of the first hot air W1 is preferably 0.2 m / s or higher, and more preferably 0.3 m / s or higher. Also, from the viewpoint of obtaining a softer nonwoven fabric, the wind speed of the first hot air W1 is preferably 50 m / s or lower, and more preferably 30 m / s or lower. From the viewpoint of forming a sufficient heat-sealed portion, the blowing time of the first hot air W1 is preferably 0.1 second or longer, more preferably 0.2 second or longer, and even more preferably 0.3 second or longer. Also, from the viewpoint of further enhancing the softness of the nonwoven fabric 10, the blowing time of the first hot air W1 is preferably 3 seconds or shorter, more preferably 2 seconds or shorter, and even more preferably 1 second or shorter.

[0057] In step (III), as shown in Fig. 7(B), the uneven perforated nonwoven fabric 102 obtained in step (II) is stretched in a direction orthogonal to one direction. The stretching direction can be determined as appropriate. For example, in the shape of the perforated portion of the nonwoven fabric before stretching, when the opening ratio (the maximum length in the MD direction (or longitudinal direction) of the perforated portion / the maximum length in the CD direction (or transverse direction) of the perforated portion) is greater than 1, stretching in the CD direction (or transverse direction) is preferable in that the perforated portion spreads due to stretching and a nonwoven fabric with a large opening area can be obtained. In this case, the opening ratio is preferably more than 1 and 15 or less, more preferably 1.5 or more and 10 or less. Further, when the opening ratio is 1 or less, stretching in the MD direction (or longitudinal direction) is preferable in that the perforated portion spreads due to stretching and a nonwoven fabric with a large opening area can be obtained. In this case, the opening ratio is preferably 0.06 or more and 1 or less, more preferably 0.1 or more and 0.6 or less. The stretching direction can be either the MD direction or the CD direction, or both, but is preferably a direction orthogonal to the extending direction of the longitudinal ridge portion 95 described above. That is, the stretching direction is preferably a direction orthogonal to the extending direction (first direction D1) of the first concave portion 125A in the support 120 and a direction orthogonal to the extending direction (first direction D1) of the concave portion 132 in the pushing member 130. In the uneven perforated nonwoven fabric 102 shown in Figs. 7(A) and 7(B), as an example, the extending direction of the longitudinal ridge portion 95 is shown as the MD direction, and it is stretched in the CD direction orthogonal thereto.

[0058] The stretching treatment in step (III) is preferably carried out under the following conditions. That is, it is preferable to perform heat setting by heat treatment by air-through while stretching in the MD direction or the CD direction, or both directions, by means of a device such as a tenter, so as to easily maintain the opening shape during stretching. Further, stretching may be performed in the MD direction at the outlet of the heat treatment net of the air-through device. In this case, the transverse direction of the nonwoven fabric may be the MD direction. When the stretching ratio is 1.1 times or more and 3 times or less, more preferably 1.2 times or more and 2 times or less, based on the original length, a nonwoven fabric with a preferably shaped opening portion can be obtained in terms of appearance. The temperature of the hot air WB in the heat treatment is preferably -30°C or higher and 40°C or lower, more preferably -25°C or higher and 35°C or lower, relative to the melting point of the constituent fibers (thermoplastic fibers). From the perspective of heat-setting the aperture shape, the wind speed of the hot air WB is preferably 0.3 m / s or higher, more preferably 0.4 m / s or higher. Also, from the perspective of preventing the thickness of the non-woven fabric from decreasing too much, the wind speed of the hot air WB is preferably 20 m / s or lower, more preferably 10 m / s or lower. From the perspective of heat-setting the aperture shape, the spraying time of the hot air WB is preferably 1 second or longer, more preferably 2 seconds or longer, and even more preferably 3 seconds or longer. Also, from the perspective of preventing the resin melted at the fusion point from concentrating too much, the spraying time of the first hot air W1 is preferably 30 seconds or shorter, more preferably 20 seconds or shorter, and even more preferably 10 seconds or shorter. After heat setting, it is preferable to cool the non-woven fabric in the stretched state so that the temperature is 50°C or lower than the temperature of the hot air WB. This is because the aperture shape during stretching is more likely to be maintained, resulting in a larger aperture area.

[0059] Next, in the second fusion step of step (IV), the second hot air W2 is sprayed onto the concavo-convex aperture non-woven fabric 102A in the stretched state. As a result, further fusion of the fibers in the concavo-convex aperture non-woven fabric 102A in the stretched state is performed to form the stretched concavo-convex aperture non-woven fabric 103 (Figure 8). This concavo-convex aperture non-woven fabric 103 becomes the aforementioned non-woven fabric 10. At this time, it is preferable to spray the second hot air W2 from the other surface side 10B of the stretched concavo-convex aperture non-woven fabric 102A (the side opposite to the surface in contact with the support 120). Thereby, a non-woven fabric with reduced fuzz etc. on the surface in contact with the skin can be obtained. Also, the spraying of the second hot air W2 may be performed simultaneously, combining the aforementioned steps (III) and (IV).

[0060] The stretched concavo-convex perforated nonwoven fabric 103 is fusion-fixed by step (IV) in a state where the fibers are stretched along the stretching direction (MD direction or CD direction, or both directions) in step (III). In particular, the longitudinal ridge portion 95 around the perforated portion 3 extends in the stretching direction and deforms so as to face in a direction intersecting the MD direction and the CD direction between the transverse ridge portions 91, 91. As a result, the transverse ridge portion 91 becomes the top portion 1 in the nonwoven fabric 10, and the deformed portion of the longitudinal ridge portion 95 becomes the saddle portion 5 in the nonwoven fabric 10. The degree of the average fiber orientation in the longitudinal direction Y of the top portion 1 and the saddle portion 5 in the nonwoven fabric 10 (stretched concavo-convex perforated nonwoven fabric 103) is appropriately set according to the degree of stretching in step (III). Further, depending on the degree of stretching in step (III), the degree of meandering (for example, the arrow S in FIG. 1) of the shape of the continuous fiber layer in which the top portion 1 and the saddle portion 5 in the nonwoven fabric 10 are alternately arranged, and the presence or absence of a continuous shape in the planar direction of the hollow region 1C are appropriately set. Further, in order to make the wall portion 15 have a shape inclined in the thickness direction like a mortar as described above, it can be obtained by making the protruding shape of the support 120 a trapezoidal shape in which the cross-sectional area of the bottom is wider than the cross-sectional area of the top.

[0061] The temperature of the second hot air W2 is set to be equal to or higher than the melting point of the constituent fibers of the stretched concavo-convex perforated nonwoven fabric 102A. Considering a general fiber material used for this type of product, the temperature of the second hot air W2 is preferably 0°C or higher and 40°C or lower higher than the melting point of the constituent fibers (thermoplastic fibers) of the concavo-convex perforated fiber web 101, and more preferably 5°C or higher and 45°C or lower higher. From the viewpoint of good nonwoven fabric formation, the wind speed of the second hot air W2 is preferably 0.2 m / s or more, and more preferably 0.3 m / s or more. Further, from the viewpoint of making the nonwoven fabric 10 softer and forming the hollow region 1C well, the wind speed of the second hot air W2 is preferably 50 m / s or less, and more preferably 30 m / s or less. From the viewpoint of forming a sufficient heat-sealed portion, the spraying time of the second hot air W2 is preferably 0.1 second or more, more preferably 0.2 second or more, and still more preferably 0.3 second or more. Further, from the viewpoint of further enhancing the softness of the nonwoven fabric 10, the spraying time of the second hot air W2 is preferably 30 seconds or less, more preferably 25 seconds or less, and still more preferably 20 seconds or less.

[0062] By the method for manufacturing a nonwoven fabric of the present embodiment including the above-described steps (I), (II), (III), and (IV), the nonwoven fabric of the present invention can be suitably manufactured.

[0063] In the method for manufacturing a nonwoven fabric of the present embodiment, in the first fusing step of the above-described step (II), after removing the pushing member 130 from the support 120 and before spraying the first hot air W1, as shown in FIG. 13, it is preferable to have a shaping step of spraying air WA onto the concavo-convex perforated fiber web 101 on the support 120. By this spraying, fibers on the surface of the protrusion 121, for example, (i) fibers remaining at the top of the protrusion 121 and (ii) fibers shaped in the thickness direction along the wall surface of the protrusion 121 are pushed along the wall surface of the protrusion 121. Thereby, a wall portion 15 with increased fiber density and high strength is formed. Further, the fiber layers pushed into the first recess 125A and the second recess 125C of the support 120 in the step (I) are further pushed by the spraying of the air WA, and the pushing height positions thereof are aligned with each other. Thereby, the heights in the thickness direction of the horizontal ridges 91 and the vertical ridges 95 in the concavo-convex perforated nonwoven fabric 102 become equal. Furthermore, it is preferable in that the heights of the wall portions 15 are aligned and a nonwoven fabric with a large thickness H1 can be obtained.

[0064] The spraying of the air WA can be performed by commonly used means. For example, it can be performed using an air duster gun, a high-speed spraying nozzle, or the like.

[0065] From the perspective of better performing the above-described shaping, it is preferable to blow the air WA from directly above the concavo-convex perforated fiber web 101 shaped along the support 120. Specifically, the blowing angle of the air WA is preferably an angle of 90° ± 30° with 90° being directly above.

[0066] The temperature of the air WA is below the melting point of the constituent fibers of the concavo-convex perforated fiber web 101. Considering general fiber materials used for this type of product, the temperature of the air WA is preferably -115°C or higher and -0°C or lower, more preferably -65°C or higher and -5°C or lower, with respect to the melting point of the constituent fibers (thermoplastic fibers) of the concavo-convex perforated fiber web 101. It is preferably carried out at a temperature such that the fibers do not thermally fuse. From the perspective of increasing the density of the fibers to form a stronger wall portion 15, the wind speed of the air WA is preferably 2 m / s or higher, more preferably 3 m / s or higher, and even more preferably 4 m / s or higher. Also, from the perspective of not overly disturbing the concavo-convex perforated fiber web 101 on the support, the wind speed of the air WA is preferably 50 m / s or lower, more preferably 30 m / s or lower, and even more preferably 20 m / s or lower. From the perspective of making the height of the wall portion 15 uniform, the blowing time of the air WA is preferably 0.5 seconds or longer, more preferably 1 second or longer. Also, from the perspective of making the device more compact, the blowing time of the air WA is preferably 10 seconds or shorter, more preferably 5 seconds or shorter.

[0067] Note that in the above manufacturing method, the pushing member 130 is not limited to one having a pushing portion 131 continuous in the first direction D1 as shown in FIG. 11. For example, the pushing portion 131 may be in a lattice shape, and the spaces between the lattice-shaped pushing portions 131 may be box-shaped recesses 132. In this case, lattice-shaped convex portions are formed by the longitudinal ridges 95 and the transverse ridges 91 shaped in step (I), and the heights of the longitudinal ridges 95 and the transverse ridges 91 become higher, and the concavities and convexities become clearer. As a result, in the obtained nonwoven fabric 10, the heights of the top portions 1 and the saddle portions 5 become higher, and the concavities and convexities become clearer.

[0068] As the thermoplastic fibers constituting the nonwoven fabric of the present invention, those commonly used as materials for nonwoven fabrics can be adopted without particular limitation. For example, fibers composed of a single resin component or composite fibers composed of a plurality of resin components may be used. Examples of the composite fibers include a core-sheath structure, a side-by-side structure, and the like. When using a composite fiber containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, a composite fiber having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air sprayed onto the fiber web in the manufacturing process is preferably equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component. More preferably, it is a temperature that is equal to or higher than the melting point of the low melting point component and 10°C lower than the melting point of the high melting point component. Even more preferably, it is a temperature that is 5°C or more higher than the melting point of the low melting point component and 20°C or more lower than the melting point of the high melting point component. Also, from the viewpoint of elasticity, among the composite fibers having a core-sheath structure, the more the core, which is the high melting point component, the higher the elasticity. Therefore, it is preferable that the core component has a larger cross-sectional area ratio. Specific examples of the composite fiber having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component include a composite fiber having a core-sheath structure in which the sheath is a polyethylene resin (hereinafter also referred to as PE) and the core is a polyethylene terephthalate resin (hereinafter also referred to as PET). In addition, in the composite fiber having a core-sheath structure, when the resin component of the sheath has a lower glass transition point than the resin component of the core (hereinafter referred to as a low glass transition point resin component. For example, the resin component of the core is PET and the resin component of the sheath is PE), by reducing the mass ratio of the low glass transition point resin component, the thickness recovery of the nonwoven fabric can be further enhanced.

[0069] The nonwoven fabric of the present invention can be used for various applications. For example, it can be used as a constituent member of various absorbent articles. The various absorbent articles widely include articles used for absorbing liquids discharged from the body, such as adult and infant diapers, sanitary napkins, panty liners, urine collection pads, and the like.

[0070] The absorbent article having the nonwoven fabric of the present invention typically comprises a topsheet, a backsheet, and a liquid-retaining absorbent body interposed between both sheets. In the absorbent article, the nonwoven fabric of the present invention can be suitably used as the topsheet that contacts the wearer's skin.

Example

[0071] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not construed as being limited thereto.

[0072] [Example] Based on the manufacturing method shown in FIGS. 6(A) and (B), the following steps were carried out to produce the nonwoven fabric shown in FIG. 14, which was used as the nonwoven fabric sample of the example. First, a fiber web having a basis weight of 10 g / cm was made using thermoplastic fibers of core-sheath type (polyethylene terephthalate (PET) / polyethylene (PE)=5:5) with a fineness of 1.3 dtex as the upper layer on one surface side 10T. 2 On the fiber web, a fiber web having a basis weight of 20 g / cm was laminated using thermoplastic fibers of core-sheath type (polyethylene terephthalate (PET) / polyethylene (PE)=5:5) with a fineness of 4.4 dtex as the lower layer on the other surface side 10B to produce an unfused fiber web 100. Both thermoplastic fibers were subjected to hydrophilic oil agent treatment. 2 Next, the fiber web 100 was placed on the support 120, and the pressing member 130 was pressed into the support 120 from above the fiber web 100 to perform a shaping process to form a concavo-convex perforated fiber web 101 (step (I)). ​The pushing by the above-described pushing member 130 was performed as follows. In the support 120, the MD length of the protrusion 121 including the spire portion 122 in plan view was set to 9 mm, and the protrusion interval in the MD direction was set to 6 mm. Also, the CD length of the protrusion 121 was set to 3 mm, and the protrusion interval in the CD direction was set to 3 mm. The protrusion height including the spire portion 122 was set to 17 mm. The planar shape of the protrusion 121 from the spire portion 122 side was made square. The width of the pushing portion 131 of the pushing member 130 in the CD direction was set to 2 mm, the interval between the pushing members 130 in the CD direction was set to 6 mm, and the pushing amount by the pushing member 130 was set to 17 mm. Next, on the support 120, the first hot air W1 was blown from the other surface side 10B (the opposite side of the surface in contact with the support 120) toward the web to fuse the fibers together, thereby producing a concavo-convex perforated nonwoven fabric (Step (II)). The first hot air W1 had a temperature of 160°C, a wind speed of 3.0 m / s, and a blowing time of 3 seconds. In the same Step (II), after removing the pushing member 130 from the support 120 and before blowing the first hot air W1, air WA was blown from the other surface side 10B using an air duster gun directly above the concavo-convex perforated fiber web 101 on the support 120. The air WA had a temperature of 25°C, a wind speed of 30 m / s, and a blowing time of 10 seconds. Next, the concavo-convex perforated fiber web 102 was peeled off from the support 120, and in a state of being stretched 1.4 times in the CD direction, hot air WB was blown from the other surface side 10B toward the nonwoven fabric on the net to fuse the fibers together (Step (III)). The hot air WB had a temperature of 130°C, a wind speed of 2.0 m / s, and a blowing time of 3 seconds. Next, the concavo-convex perforated fiber web 102A was peeled off from the net, and the second hot air W2 was blown from the other surface side 10B toward the nonwoven fabric on the net to fuse the fibers together, thereby producing a stretched concavo-convex perforated nonwoven fabric 103 (Step (IV)). The second hot air W2 had a temperature of 140°C, a wind speed of 2.0 m / s, and a blowing time of 6 seconds. The obtained nonwoven fabric was stretched 1.35 times in the CD direction with respect to the CD direction pitch of the protrusions 121 of the support. This was used as the nonwoven fabric sample of the example (Fig. 14).

[0073] The produced nonwoven fabric sample of the example (elongated uneven perforated nonwoven fabric) had a wall portion 15 extending perpendicular to the plane direction of the nonwoven fabric sample, and the heights in the thickness direction of the top portion 1 and the saddle portion 5 on the surface of one surface side 10T were equal. Also, the average opening area when projected from one surface side 10T of the opening portion 3 was 28 mm 2 , the average opening area of one surface side 10T was 28.6 mm 2 , the average opening area of the other surface side 10B was 28 mm 2 , the average opening area ratio when projected from one surface side 10T was 24%, the average opening area ratio of one surface side 10T was 24.5%, the average opening area ratio of the other surface side 10B was 24%, the angle θ of the wall portion 15 was 90°, 0.5 gf / cm 2 The nonwoven fabric thickness under load was 3.4 mm, and the basis weight was 25 g / m 2 . The thickness of the top portion 1 was 2.0 mm, the thickness of the saddle portion 5 was 1.8 mm, the thickness of the wall portion 15 was 3.4 mm, the height of the hollow region 1C was 1.4 mm, and the thickness of the wall portion 15 in the plane direction was 1.5 mm. The average fiber orientation degree in the longitudinal direction Y (corresponding to the MD direction) of the top portion 1 and the saddle portion 5 was 1.24 for the top portion 1 and 0.905 for the saddle portion 5, and the orientation degree ratio of the top portion 1 to the saddle portion 5 (average fiber orientation degree in the longitudinal direction Y of the top portion 1 / average fiber orientation degree in the longitudinal direction Y of the saddle portion 5) was 1.37. From these, it was found that the top portion 1 was oriented in the longitudinal direction Y and the saddle portion 5 was oriented in the transverse direction X. The obtained nonwoven fabric sample of the example (elongated uneven perforated nonwoven fabric) had a large opening area of the opening portion and a large thickness, so it was possible to enhance the liquid permeability that can also cope with highly viscous body fluids such as menstrual blood and soft feces.

Explanation of symbols

[0074] 1 Top portion 2 Bottom portion 3 Opening portion 5 Saddle portion 15 Wall portion X, Y Two mutually perpendicular directions J Direction intersecting two mutually perpendicular directions

Claims

1. A nonwoven fabric having one surface side and another surface side opposite to the one surface side, in which a vertical direction and a horizontal direction are mutually perpendicular when viewed in a plan view from the one surface side, and including fiber fusion portions at intersections between fibers, When viewed in a plan view from the one surface side, the nonwoven fabric has a plurality of apexes arranged in a staggered pattern along the two directions, saddle portions connecting adjacent apexes along a direction intersecting the two directions, and a bottom portion located in a recessed position toward the other surface side between the adjacent apexes and saddle portions, a wall portion that is continuous in a thickness direction is disposed between the top portion and the bottom portion and between the saddle portion and the bottom portion; The bottom portion has an opening penetrating therethrough in a thickness direction, When viewed in a plane from the one surface side, the average fiber orientation degree in the longitudinal direction is higher in the peak portion than in the saddle portion.

2. The nonwoven fabric for absorbent articles according to claim 1 , wherein, when viewed from above from the one surface side, the bottom portion is surrounded by a plurality of peaks and a plurality of saddles.

3. The nonwoven fabric for absorbent articles according to claim 1 or 2, wherein the wall portion extends perpendicular to a planar direction of the nonwoven fabric.

4. The nonwoven fabric for absorbent articles according to any one of claims 1 to 3, wherein the heights of the peaks and the saddles in the thickness direction are equal to each other.

5. 0.5 gf / cm ２ The nonwoven fabric for absorbent articles according to any one of claims 1 to 4, which has a thickness under load of 0.8 mm or more and 10 mm or less.

6. The nonwoven fabric for absorbent articles according to any one of claims 1 to 5, further comprising a sublayer including the fused fiber portion on the other surface side.

7. a pressing step of placing an unfused fiber web on a support having an uneven shape with a plurality of protrusions and recesses between the protrusions, pressing the fiber web along the recesses with a pressing part of a pressing member to give it a shape, and opening holes at locations corresponding to the protrusions to form an uneven perforated fiber web; a first fusion step of blowing a first hot air stream onto the porous fiber web after removing the pushing member from the support to fuse the fibers together to obtain a porous nonwoven fabric; stretching the porous nonwoven fabric in a direction perpendicular to the one direction; a second fusion step of blowing a second hot air stream onto the stretched porous nonwoven fabric to fuse the fibers together to obtain a stretched porous nonwoven fabric; A method for producing a nonwoven fabric for absorbent articles comprising the steps of:

Images