Nonwoven fabric for absorbent articles and method for manufacturing the nonwoven fabric

Abstract

To provide a nonwoven fabric for absorbent article that can suppress delamination and is excellent in liquid permeability and liquid repellency.SOLUTION: A nonwoven fabric for absorbent article 16 has a first fiber layer 26 and a second fiber layer 28 in order in a thickness direction T. The first fiber layer 26 has a first surface 22 and is formed of thermally fusible fibers. The second fiber layer 28 includes water-absorbing fibers and thermally fusible fibers. A portion of the thermally fusible fibers of the first fiber layer 26 enters into the second fiber layer 28 and fuses with a portion of the thermally fusible fibers of the second fiber layer 28. The water-absorbing fibers of the second fiber layer 28 are not exposed to the first surface 22.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a nonwoven fabric for absorbent articles and a method for manufacturing the nonwoven fabric.

Background Art

[0002] As a nonwoven fabric for absorbent articles, for example, Patent Document 1 discloses a composite nonwoven fabric in which a cotton web and a synthetic short fiber web containing heat-adhesive short fibers are laminated, and the constituent fibers of the cotton web, the constituent fibers of the cotton web and the synthetic short fiber web, and the constituent fibers of the synthetic short fiber web are three-dimensionally entangled and integrated, and the intersections of the fibers are heat-bonded by the fusion of the heat-adhesive component.

[0003] Further, Patent Document 2 discloses a nonwoven fabric for absorbent articles including a first fiber layer and a second fiber layer located on one main surface of the first fiber layer, the first fiber layer including first core-sheath composite fibers, the second fiber layer including second core-sheath composite fibers and cellulose-based fibers, the fineness of the first core-sheath composite fibers being smaller than the fineness of the second core-sheath composite fibers, the fineness of the first core-sheath composite fibers being 1.0 to 2.8 dtex, the fineness of the second core-sheath composite fibers being 1.7 to 5.6 dtex, the fineness of the cellulose-based fibers being 1.2 to 6.0 dtex, and the second fiber layer containing cellulose-based fibers at a ratio of 5% by mass to 40% by mass based on the total mass of the second fiber layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The nonwoven fabric of Patent Document 1 is formed by subjecting a laminated web to high-pressure fluid treatment, thereby three-dimensionally entangling and integrating the constituent fibers of the cotton web with each other, the constituent fibers of the cotton and the synthetic staple fiber web with each other, and the constituent fibers of the synthetic staple fiber web with each other. Since the web of the nonwoven fabric receives a large force in the thickness direction by the high-pressure fluid, the bulkiness is reduced. When the nonwoven fabric is used as the surface sheet of an absorbent article, the liquid hardly permeates in the thickness direction due to the low bulkiness, and the liquid permeability is poor.

[0006] Patent Document 2 describes that it is preferable to join the first fiber layer and the second fiber layer by the air-through method (hot air penetration heat treatment method) because it is easy to obtain a nonwoven fabric with good texture. However, there is a problem that since there are few contact points between the fibers of the first fiber layer and the second fiber layer, there are few fused portions, and the first fiber layer and the second fiber layer are likely to peel off from each other. The more the cellulose-based fibers contained in the second fiber layer, the fewer the fused portions between the first fiber layer and the second fiber layer, and thus the easier it is to peel off between the first fiber layer and the second fiber layer.

[0007] An object of the present invention is to provide a nonwoven fabric for an absorbent article that can suppress interlayer peeling and has excellent liquid permeability, and a method for manufacturing the nonwoven fabric for an absorbent article.

Means for Solving the Problems

[0008] The present invention is a nonwoven fabric for an absorbent article having a first fiber layer and a second fiber layer in order in the thickness direction, wherein the first fiber layer has a first surface and is made of heat-fusible fibers, and the second fiber layer contains water-absorbent fibers and heat-fusible fibers. A part of the heat-fusible fibers of the first fiber layer penetrates into the second fiber layer and is fused with a part of the heat-fusible fibers of the second fiber layer, and the water-absorbent fibers of the second fiber layer are not exposed on the first surface.

[0009] The present invention provides a method for manufacturing a non-woven fabric for absorbent articles, which includes: a first step of injecting gas from the side of a first fiber web made of heat-fusible fibers, which is stacked in the thickness direction in order, onto a second fiber web containing water-absorbent fibers and heat-fusible fibers; and a second step of melting the surfaces of the heat-fusible fibers of the first fiber web and the heat-fusible fibers of the second fiber web and fusing the heat-fusible fibers to each other. In the first step, the gas is injected under the condition that the amount of movement of the heat-fusible fibers of the first fiber web in the thickness direction is larger than the amount of movement in the width direction perpendicular to the machine direction.

Advantages of the Invention

[0010] The non-woven fabric for absorbent articles according to the present invention can suppress delamination between layers and is excellent in liquid permeability. The method for manufacturing a non-woven fabric for absorbent articles according to the present invention can suppress delamination between layers and obtain a non-woven fabric excellent in liquid permeability.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0012] Embodiments of the present invention relate to the following aspects.

[0013] [Aspect 1] A non-woven fabric for absorbent articles comprising a first fiber layer and a second fiber layer in order in the thickness direction, The first fiber layer has a first surface and is made of heat-fusible fibers, The second fiber layer includes water-absorbent fibers and heat-fusible fibers, A part of the heat-fusible fibers of the first fiber layer penetrates into the second fiber layer and is fused with a part of the heat-fusible fibers of the second fiber layer, and the water-absorbent fibers of the second fiber layer are not exposed on the first surface. Non-woven fabric. In the non-woven fabric, a part of the heat-fusible fibers of the first fiber layer and a part of the heat-fusible fibers of the second fiber layer are fused together. That is, a part of the heat-fusible fibers of the first fiber layer penetrates into the second fiber layer, contacts a part of the heat-fusible fibers contained in the second fiber layer, and is fused. Therefore, since the first fiber layer and the second fiber layer are firmly joined in the non-woven fabric, delamination between the first fiber layer and the second fiber layer can be suppressed. The water-absorbent fibers of the second fiber layer are held in the second fiber layer by a part of the heat-fusible fibers of the first fiber layer and a part of the heat-fusible fibers of the second fiber layer that are fused to each other. Since the water-absorbent fibers of the second fiber layer are not exposed on the first surface, they are difficult to fall off from the first surface. Therefore, the non-woven fabric suppresses the shedding of the fibers of the second fiber layer.

[0014] When the non-woven fabric is used as the surface sheet of an absorbent article and the first surface is the skin-facing surface, the body fluid supplied to the skin-facing surface moves from the skin-facing surface into the interior of the first fiber layer. When the second surface is the skin-facing surface, the body fluid supplied to the skin-facing surface moves from the skin-facing surface into the interior of the second fiber layer. Since the non-woven fabric includes a first fiber layer made of heat-fusible fibers and a second fiber layer including water-absorbent fibers and heat-fusible fibers, it has a high bulk and excellent liquid permeability. As a result, the non-woven fabric can suppress delamination between the first fiber layer and the second fiber layer and has excellent liquid permeability.

[0015] [Aspect 2] The nonwoven fabric according to Aspect 1, wherein the first fiber layer has no recesses recessed in the thickness direction on the first surface. If recesses recessed in the thickness direction were formed on the first surface, the bulk of that portion would be low, resulting in a decrease in liquid permeability. On the other hand, since the nonwoven fabric of the present invention has no recesses recessed in the thickness direction on the first surface, the accumulation of body fluid at specific locations is suppressed. Therefore, the nonwoven fabric is excellent in liquid permeability.

[0016] [Aspect 3] The nonwoven fabric according to Aspect 1 or 2, further comprising a third fiber layer made of heat-fusible fibers on the side of the second fiber layer opposite to the first fiber layer. In the nonwoven fabric, the surface of the third fiber layer disposed on the side of the second fiber layer opposite to the first fiber layer, opposite to the second fiber layer, becomes the second surface. The second fiber layer is covered by the third fiber layer, suppressing the exposure of the water-absorbing fibers from the second surface. Therefore, the nonwoven fabric suppresses the shedding of the water-absorbing fibers.

[0017] [Aspect 4] The nonwoven fabric according to Aspect 3, wherein a further part of the heat-fusible fibers of a part of the first fiber layer that has entered the second fiber layer penetrates the second fiber layer, enters the third fiber layer, and fuses with a part of the heat-fusible fibers of the third fiber layer.

[0018] In the nonwoven fabric, a further part of a part of the heat-fusible fibers of the first fiber layer is fused with a part of the heat-fusible fibers of the third fiber layer. That is, a part of the heat-fusible fibers of the first fiber layer has entered the second fiber layer, and a further part of it penetrates the second fiber layer, enters the third fiber layer, and fuses with a part of the heat-fusible fibers of the third fiber layer. Therefore, in addition to between the first fiber layer and the second fiber layer, the nonwoven fabric has the space between the second fiber layer and the third fiber layer firmly joined, so that delamination between layers can be suppressed. The water-absorbent fibers of the second fiber layer are held within the second fiber layer by some of the heat-fusible fibers of the first fiber layer that are fused to each other, some of the heat-fusible fibers of the second fiber layer, and some of the heat-fusible fibers of the first fiber layer that penetrate the second fiber layer and some of the heat-fusible fibers of the third fiber layer. Therefore, the non-woven fabric further suppresses the shedding of the fibers of the second fiber layer.

[0019] [Aspect 5] The non-woven fabric according to Aspect 4, wherein a part of the heat-fusible fibers of the second fiber layer penetrates into the third fiber layer and is fused with a further part of the fusible fibers of the first fiber layer and a part of the heat-fusible fibers of the third fiber layer.

[0020] A part of the heat-fusible fibers of the second fiber layer has penetrated into the third fiber layer and is fused with a part of the heat-fusible fibers of the third fiber layer in the third fiber layer. Further, it is fused with a further part of the heat-fusible fibers of the first fiber layer that penetrates the second fiber layer and enters the third fiber layer. Therefore, since the non-woven fabric has a stronger bond between the second fiber layer and the third fiber layer, delamination between layers can be further suppressed. The water-absorbent fibers of the second fiber layer are held within the second fiber layer by some of the heat-fusible fibers of the second fiber layer that are fused to each other and some of the heat-fusible fibers of the third fiber layer, and some of the heat-fusible fibers of the first fiber layer that penetrate the second fiber layer and some of the heat-fusible fibers of the second fiber layer. Therefore, the non-woven fabric further suppresses the shedding of the fibers of the second fiber layer.

[0021] [Aspect 6] The non-woven fabric according to any one of Aspects 1 to 5, wherein the first surface of the first fiber layer is the skin-facing surface. When the nonwoven fabric is used as the surface sheet of the absorbent article and the first surface is the skin-facing surface, the body fluid supplied to the skin-facing surface migrates from the skin-facing surface into the interior of the first fiber layer. Since the water-absorbing fibers are not exposed on the skin-facing surface, it is difficult for the body fluid to remain on the skin-facing surface. The body fluid that has migrated into the interior of the first fiber layer further migrates in the thickness direction and reaches the interface between the first fiber layer and the second fiber layer. The body fluid smoothly migrates to the second fiber layer because a part of the heat-fusible fibers of the first fiber layer penetrates into the second fiber layer. The body fluid that has migrated to the second fiber layer is absorbed by the water-absorbing fibers contained in the second fiber layer. When the nonwoven fabric is used as the surface sheet of the absorbent article, the body fluid absorbed by the water-absorbing fibers is absorbed by the absorber disposed on the non-skin side. In this way, the nonwoven fabric smoothly migrates the body fluid supplied to the skin-facing surface from the first fiber layer to the second fiber layer and absorbs it with the water-absorbing fibers of the second fiber layer, so it has excellent liquid drainage properties.

[0022] [Aspect 7] The nonwoven fabric according to Aspect 6, wherein the basis weight of the second fiber layer is uniform in the plane direction. Since the basis weight of the second fiber layer is uniform in the plane direction, the body fluid supplied to the skin-facing surface and migrating in the thickness direction is uniformly absorbed regardless of the position in the plane direction. Therefore, the nonwoven fabric can obtain excellent liquid drainage properties regardless of the position in the plane direction.

[0023] [Aspect 8] The nonwoven fabric according to Aspect 6 or 7, wherein the second fiber layer contains 40% by mass or more and 70% by mass or less of the water-absorbing fibers. Since the nonwoven fabric contains 40% by mass or more and 70% by mass or less of the water-absorbing fibers in the second fiber layer, the body fluid discharged from the wearer is more reliably absorbed by the water-absorbing fibers. Therefore, the nonwoven fabric has excellent liquid drainage properties when body fluid is repeatedly supplied.

[0024] [Aspect 9] A first step of injecting gas from the first fiber web side to a first fiber web made of heat-fusible fibers and a second fiber web containing water-absorbing fibers and heat-fusible fibers, which are stacked in order in the thickness direction; A second step of melting the surfaces of the heat-fusible fibers of the first fiber web and the heat-fusible fibers of the second fiber web to fuse the heat-fusible fibers together; The first step is a method for manufacturing a nonwoven fabric for absorbent articles, in which the gas is injected under the condition that the amount of movement of the heat-fusible fibers of the first fiber web in the thickness direction is larger than the amount of movement in the width direction orthogonal to the machine direction.

[0025] In the first step of injecting gas from the first fiber web side into the first fiber web made of heat-fusible fibers and the second fiber web containing water-absorbent fibers and heat-fusible fibers that are stacked in the thickness direction, since the gas is injected under the condition that the amount of movement of the heat-fusible fibers of the first fiber web in the thickness direction is larger than the amount of movement in the width direction orthogonal to the machine direction, the nonwoven fabric according to Embodiment 1 can be formed. That is, the present manufacturing method is a nonwoven fabric for absorbent articles having a first fiber layer and a second fiber layer in order in the thickness direction. The first fiber layer is made of heat-fusible fibers and has a first surface. The second fiber layer contains water-absorbent fibers and heat-fusible fibers. A part of the heat-fusible fibers of the first fiber layer penetrates into the second fiber layer and is fused with the heat-fusible fibers of the second fiber layer, and the water-absorbent fibers of the second fiber layer are not exposed on the first surface, and a nonwoven fabric can be formed.

[0026] Hereinafter, the nonwoven fabric for absorbent articles according to the embodiment will be described in detail with reference to the drawings.

[0027] (Configuration of Absorbent Article) FIG. 1 is a diagram schematically showing an absorbent article 10 according to the embodiment, FIG. 2 is an end view schematically showing a cross section along line II-II of FIG. 1, and FIG. 3 is a partially enlarged cross-sectional view of the surface sheet.

[0028] The absorbent article 10 shown in Fig. 1 is a sanitary napkin, having a longitudinal direction L, a width direction W, and a thickness direction T that are orthogonal to each other, and including a main body portion 12 extending in the longitudinal direction L and a pair of flap portions 14 extending on both sides in the width direction W substantially at the center in the longitudinal direction L. Since the longitudinal direction L, the width direction W, and the thickness direction T of the absorbent article 10 are the same as those of each material described later, hereinafter, the longitudinal direction L, the width direction W, and the thickness direction T are commonly used for the absorbent article 10 and each of its materials. The "skin-facing side" and the "non-skin-facing side" respectively mean the side closer to and farther from the wearer's skin surface in the thickness direction T when the absorbent article 10 is worn by the wearer of the absorbent article 10, and are commonly used for each material of the absorbent article 10. In this specification, the "skin-facing surface" and the "non-skin-facing surface" of the absorbent article 10 and each material constituting the absorbent article 10 (for example, the top sheet, the absorbent body, the back sheet, etc.) may be simply referred to as the "skin-facing surface" and the "non-skin-facing surface", respectively.

[0029] As shown in FIG. 2, the absorbent article 10 includes a topsheet 16, an absorber 18, and a backsheet 20 in this order from the skin-facing side in the thickness direction T. The topsheet 16 is a liquid-permeable sheet located on the skin-facing side of the wearer. The absorber 18 is a liquid-absorbent and liquid-retaining material located between the topsheet 16 and the backsheet 20. Examples of the material constituting the absorber 18 include pulp fibers, synthetic fibers, and absorbent polymers. The backsheet 20 is a liquid-impermeable sheet located on the non-skin-facing side of the wearer. Examples of the backsheet 20 include any liquid-impermeable sheet such as a liquid-impermeable nonwoven fabric, a synthetic resin film, a composite sheet thereof, an SMS nonwoven fabric, etc. An exterior sheet (not shown) that reinforces the backsheet 20 and improves the touch may be laminated on the non-skin-facing side of the backsheet 20. Examples of the exterior sheet include any water-repellent sheet such as the same material as the backsheet 20, a water-repellent nonwoven fabric, a synthetic resin film, a composite sheet thereof, etc. The absorber 18, the topsheet 16, and the backsheet 20 are joined by an adhesive, respectively. As the adhesive for joining between the topsheet 16, the absorber 18, and the backsheet 20, a known material generally used in the absorbent article 10, for example, a thermoplastic adhesive, can be used.

[0030] (Topsheet) Hereinafter, the topsheet 16 will be described with reference to FIG. 3. The topsheet 16 is made of a nonwoven fabric according to this embodiment. The topsheet 16 has a longitudinal direction L, a width direction W, and a thickness direction T, and has a first surface 22 on one surface and a second surface 24 on the side opposite to the first surface 22. The first surface 22 and the second surface 24 intersect the thickness direction T, respectively. The first surface 22 and the second surface 24 according to this embodiment are each substantially flat. One direction in the thickness direction T is defined as upward, and the other direction is defined as downward.

[0031] The surface sheet 16 includes a first fiber layer 26 and a second fiber layer 28 in the above order in the thickness direction T. The first fiber layer 26 is made of heat-fusible fibers and has a first surface 22 that becomes the skin-facing surface of the surface sheet 16 (liquid-permeable sheet). The type of non-woven fabric of the surface sheet 16 is not particularly limited as long as it is a non-woven fabric that can be used for absorbent articles, but a thermal bond non-woven fabric in which heat-fusible fibers are fused together is preferred, and an air-through non-woven fabric is more preferred. The thickness of the surface sheet 16 is, for example, 0.5 to 3.0 mm.

[0032] The basis weight of the first fiber layer 26 is generally uniform in the plane direction, and is, for example, 6 to 200 g / m 2 is mentioned. The heat-fusible fibers contained in the first fiber layer 26 are fibers made of a thermoplastic resin, for example, olefin resins such as polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), etc.; polyester resins such as polyethylene terephthalate (PET), polylactic acid (PLA), etc.; known resins such as polyamide resins such as 6-nylon, etc. These resins may be used alone or in combination of two or more kinds. The structure of the fibers made of such a thermoplastic resin is not particularly limited, and examples include core-sheath type fibers such as PET / PE, side-by-side type fibers, island / seafoam type fibers, etc.; hollow type fibers; and fibers with irregular cross-sectional shapes such as flat, Y-shaped, C-shaped, etc. Fibers having these structures may be used alone or in combination of two or more kinds. The fineness of the heat-fusible fibers is, for example, 1 to 20 dtex.

[0033] The second fiber layer 28 includes water-absorbent fibers and heat-fusible fibers and has a second surface 24 that becomes the non-skin-facing surface of the surface sheet 16. The second fiber layer 28 preferably contains 40% to 60% by mass of water-absorbent fibers. The water-absorbent fibers are not exposed from the first surface 22.

[0034] The basis weight of the second fiber layer 28 is generally uniform in the plane direction, and is, for example, 6 to 200 g / m 2include. The water-absorbing fibers contained in the second fiber layer 28 include, for example, natural cellulose fibers such as pulp, cotton, and hemp; regenerated cellulose fibers such as rayon, lyocell, and cupro, etc. These cellulose fibers may be used alone or in combination of two or more kinds. Examples of the fineness of the water-absorbing fibers include 0.5 to 5.0 dtex.

[0035] The heat-fusible fibers contained in the second fiber layer 28 can be selected from the heat-fusible fibers exemplified in the first fiber layer 26, and may be the same as or different from the heat-fusible fibers of the first fiber layer 26. Examples of the fineness of the thermoplastic resin fibers contained in the second fiber layer 28 include 1 to 20 dtex. The fiber diameter of the heat-fusible fibers contained in the second fiber layer 28 may be the same as or different from the fiber diameter of the heat-fusible fibers contained in the first fiber layer 26.

[0036] The surface sheet 16 may further include a third fiber layer 30 made of heat-fusible fibers on the second surface 24 side. That is, the surface sheet 16 may include the first fiber layer 26, the second fiber layer 28, and the third fiber layer 30 in this order in the thickness direction T. The third fiber layer 30 may use the same material as the first fiber layer 26. The basis weight of the third fiber layer 30 is generally uniform in the plane direction, for example, 6 to 200 g / m 2 include. The third fiber layer 30 can have the same configuration as the first fiber layer 26. The third fiber layer 30 is in contact with the second fiber layer 28 on the surface facing the skin. When the surface sheet 16 includes the third fiber layer 30, the surface on the non-skin-facing side of the third fiber layer 30 becomes the second surface 24, which is the non-skin-facing surface of the surface sheet 16.

[0037] The boundaries between the first fiber layer 26 and the second fiber layer 28, and between the second fiber layer 28 and the third fiber layer 30 can be defined by the presence or absence of water-absorbent fibers. That is, in the cross-section of the surface sheet 16, the upper end in the thickness direction T where the water-absorbent fibers are present can be defined as the boundary between the first fiber layer 26 and the second fiber layer 28, the side where the water-absorbent fibers are present can be the second fiber layer 28, and the side where the water-absorbent fibers are absent can be the first fiber layer 26. Similarly, in the cross-section of the surface sheet 16, the lower end in the thickness direction T where the water-absorbent fibers are present can be defined as the boundary between the second fiber layer 28 and the third fiber layer 30, the side where the water-absorbent fibers are present can be the second fiber layer 28, and the side where the water-absorbent fibers are absent can be the third fiber layer 30. The boundaries between the first fiber layer 26 and the second fiber layer 28, and between the second fiber layer 28 and the third fiber layer 30 defined in this way are linear in FIG. 3, but the present invention is not limited to this, and may be slightly undulating in the thickness direction T. The water-absorbent fibers can be visually recognized by dyeing them by the method described later.

[0038] The thickness of the first fiber layer 26, that is, the height from the boundary between the first fiber layer 26 and the second fiber layer 28 to the first surface 22, can be, for example, 0.3 to 2.0 mm. The skin-facing surface (the first surface 22 of the non-woven fabric) of the first fiber layer 26 is not formed with recesses that are recessed in the thickness direction T. The recesses in this specification refer to those intentionally formed by bending or moving fibers, such as by gear processing or jetting an air jet, and do not include undulations naturally formed by the arrangement of fibers that are merely laminated. At the height from the boundary between the first fiber layer 26 and the second fiber layer 28 to the first surface 22, the minimum height is preferably 50% or more of the maximum height, and more preferably 70% to 95% or less. The thickness of the second fiber layer 28, that is, the height from the boundary between the first fiber layer 26 and the second fiber layer 28 to the boundary between the second fiber layer 28 and the third fiber layer 30, can be, for example, 0.2 to 1.0 mm. The thickness of the third fiber layer 30, that is, the height from the boundary between the second fiber layer 28 and the third fiber layer 30 to the second surface 24, can be, for example, 0.2 to 0.5 mm.

[0039] A part of the heat-fusible fibers of the first fiber layer 26 is fused with a part of the heat-fusible fibers of the second fiber layer 28 within the second fiber layer 28. That is, a part of the heat-fusible fibers of the first fiber layer 26 bends toward the second fiber layer 28 side in the thickness direction T, enters the second fiber layer 28, contacts a part of the heat-fusible fibers contained in the second fiber layer 28, and is fused.

[0040] A further part of the part of the heat-fusible fibers of the first fiber layer 26 that has entered the second fiber layer 28 is fused with a part of the heat-fusible fibers of the third fiber layer 30 within the third fiber layer 30. That is, a part of the heat-fusible fibers of the first fiber layer 26 bends toward the second fiber layer 28 side in the thickness direction T, enters the second fiber layer 28, and a further part of it penetrates the second fiber layer 28, enters the third fiber layer 30, contacts a part of the heat-fusible fibers of the third fiber layer 30, and is fused.

[0041] A part of the heat-fusible fibers of the second fiber layer 28 is fused with a part of the heat-fusible fibers of the third fiber layer 30 within the third fiber layer 30. That is, a part of the heat-fusible fibers of the second fiber layer 28 bends toward the third fiber layer 30 side in the thickness direction T, enters the third fiber layer 30, contacts a part of the heat-fusible fibers contained in the third fiber layer 30, and is fused.

[0042] (Manufacturing method) Hereinafter, the manufacturing method of the surface sheet 16 will be described with reference to FIG. 4. FIG. 4 is a schematic diagram showing the manufacturing process of the surface sheet 16 including the first fiber layer 26 and the second fiber layer 28. The surface sheet 16 is produced through a first step, a second step, a third step, and a fourth step. In FIG. 4, MD indicates the machine direction (conveying direction).

[0043] In the first step, heat-fusible fibers and water-absorbent fibers are supplied to the first carding machine 32 to form the second fiber web 34. In the second step, heat-fusible fibers are supplied to the second carding machine 36 to form the first fiber web 38. The first fiber web 38 is stacked on the second fiber web 34 to obtain a laminated web 40. The laminated web 40 is conveyed to the third step.

[0044] In the third step, first, the laminated web 40 is placed on the circumferential surface of the suction drum 42. The suction drum 42 has a fixed inner cylinder 44 and an outer cylinder 46 that is concentric with the inner cylinder 44 and has air permeability and rotates in the machine direction MD. The suction drum pressure measured by a pressure gauge for the pressure inside the suction drum is appropriately selected according to the basis weight of each fiber web and the flow rates of the first air and the second air described later. For example, it is preferably 5 - 9 kPa, and more preferably 5 - 8 kPa. The laminated web 40 is placed on the circumferential surface of the outer cylinder 46 and is conveyed in the machine direction MD at a predetermined speed, for example, a speed of 100 m / min, together with the outer cylinder 46. The inner cylinder 44 has a suction region 48. Above the suction region 48, a first manifold 50 having a plurality of nozzles arranged in the cross direction CD orthogonal to the machine direction MD and a second manifold 52 arranged in parallel with the first manifold 50 and having a plurality of nozzles arranged in the cross direction CD are provided. The nozzles have a predetermined opening diameter, for example, a diameter of 1 mm. The first manifold 50 injects first air composed of, for example, heated gas at 200°C toward the laminated web 40. The flow rate of the first air injected from the first manifold 50 is, for example, 3 - 5 m 3 / min. Subsequently, the second manifold 52 injects second air composed of, for example, heated gas at 200°C toward the laminated web 40. The flow rate of the second air injected from the second manifold 52 is, for example, 3 - 5 m 3 / min.

[0045] Due to the sequential injection of the first air and the second air, the heat - fusible fibers of the first fiber web 38 located directly below the first manifold 50 and the second manifold 52 move in the laminated web 40. When the flow rates of the first air and the second air are 3 - 5 m 3By being / min, the heat-fusible fibers of the first fiber web 38 have a greater amount of movement in the thickness direction T than in the width direction W (cross direction CD). In other words, the first air and the second air are jetted under the condition that the amount of movement in the thickness direction T is greater than the amount of movement in the cross direction CD (width direction W) orthogonal to the machine direction MD. As a result, the heat-fusible fibers of the first fiber web 38 hardly move in the width direction W, and a part of them bends toward the second fiber web 34 in the thickness direction T and enters the second fiber web 34.

[0046] The surface of the first fiber web 38 moves with little movement in the width direction W and is pressed in the thickness direction T by jetting the first air and the second air under the above-described predetermined conditions, so that an overall surface structure with less unevenness and smoother can be obtained. Therefore, the first fiber layer 26 based on the first fiber web can be disposed on the skin side to form the surface sheet 16.

[0047] In the fourth step, the laminated web 40 passes through the dryer 54. The dryer 54 blows hot air, which can melt the surface of the heat-fusible fibers, for example, at a temperature of 120°C to 150°C, onto the laminated web 40. The heat-fusible fibers of the laminated web 40 are fused to each other. As described above, since a part of the heat-fusible fibers of the first fiber web 38 has entered the second fiber web 34, in the second fiber web 34, it is welded to a part of the heat-fusible fibers contained in the second fiber web 34.

[0048] By cooling the laminated web 40 conveyed from the dryer 54 to room temperature, a surface sheet 16 that can be used for absorbent articles is obtained. Since the surface sheet (nonwoven fabric) 16 obtained as described above is an air-through nonwoven fabric, it has excellent bulkiness.

[0049] The surface sheet 16 provided with the third fiber layer 30 supplies heat-fusible fibers to a carding machine (not shown) prior to the first step to form a third fiber web, overlays the second fiber web 34 formed in the first step on the third fiber web, and further overlays the first fiber web 38 formed in the second step to form a laminated web. By subjecting the laminated web to the third step and the fourth step, a surface sheet 16 provided with the first fiber layer 26, the second fiber layer 28, and the third fiber layer 30 is obtained.

[0050] (Function and Effect) The absorbent article 10 is worn with the surface sheet 16 disposed on the side facing the wearer's skin. Body fluids discharged from the wearer are supplied to the surface sheet 16. The body fluids migrate in the thickness direction T from the first surface 22 to the first fiber layer 26. The body fluids are drawn deeper into the second fiber layer 28 by the water-absorbent fibers of the first fiber layer 26, and a part of the body fluids is absorbed by the water-absorbent fibers. The body fluids drawn and absorbed by the water-absorbent fibers are absorbed by the absorber 18 disposed on the non-skin side of the surface sheet 16.

[0051] The surface sheet 16 is for an absorbent article that includes the first fiber layer 26 and the second fiber layer 28 in order in the thickness direction T. The first fiber layer 26 has a skin-facing surface and is made of heat-fusible fibers. The second fiber layer 28 includes water-absorbent fibers and heat-fusible fibers. A part of the heat-fusible fibers of the first fiber layer 26 penetrates into the second fiber layer 28 and is fused with a part of the heat-fusible fibers of the second fiber layer 28. The water-absorbent fibers of the second fiber layer 28 are not exposed on the skin-facing surface.

[0052] A part of the heat-fusible fibers of the first fiber layer 26 and a part of the heat-fusible fibers of the second fiber layer 28 of the surface sheet 16 are fused together. That is, a part of the heat-fusible fibers of the first fiber layer 26 bends toward the second fiber layer 28 side in the thickness direction T, penetrates into the second fiber layer 28, contacts, and fuses with a part of the heat-fusible fibers included in the second fiber layer 28. Therefore, since the first fiber layer 26 and the second fiber layer 28 of the surface sheet 16 are firmly joined, delamination between the first fiber layer 26 and the second fiber layer 28 can be suppressed.

[0053] The water-absorbent fibers of the second fiber layer 28 are held within the second fiber layer 28 by a part of the heat-fusible fibers of the first fiber layer 26 that are fused to each other and a part of the heat-fusible fibers of the second fiber layer 28. Therefore, the surface sheet 16 is prevented from having the fibers of the second fiber layer 28 come off.

[0054] Since the body fluid supplied to the skin-facing surface migrates from the skin-facing surface into the first fiber layer 26 by the heat-fusible fibers of the first fiber layer 26, it is difficult for the body fluid to remain on the skin-facing surface of the surface sheet 16. Therefore, the surface sheet 16 is excellent in liquid permeability. The surface sheet 16 is an air-through nonwoven fabric. For this reason, the surface sheet 16 is excellent in bulkiness and thus excellent in liquid permeability.

[0055] Since the water-absorbent fibers are not exposed on the skin-facing surface for the body fluid that has migrated into the first fiber layer 26, the body fluid further migrates in the thickness direction T and reaches the interface between the first fiber layer 26 and the second fiber layer 28. The body fluid smoothly migrates to the second fiber layer 28 because a part of the heat-fusible fibers of the first fiber layer 26 has entered the second fiber layer 28. The body fluid that has migrated to the second fiber layer 28 is absorbed by the water-absorbent fibers contained in the second fiber layer 28. The body fluid absorbed by the water-absorbent fibers is absorbed by the absorber 18 disposed on the non-skin side. In this way, the surface sheet 16 smoothly transfers the body fluid supplied to the skin-facing surface from the first fiber layer 26 to the second fiber layer 28 and absorbs it with the water-absorbent fibers of the second fiber layer 28, so it is excellent in liquid drainage property.

[0056] As a result, the surface sheet 16 can suppress delamination between the first fiber layer 26 and the second fiber layer 28 and is excellent in liquid permeability and liquid drainage property.

[0057] In this specification, liquid permeability is evaluated by the time it takes for body fluid to completely penetrate into the surface sheet 16 from the skin-facing surface, and liquid drainage property is evaluated by the time it takes for body fluid to drain from the skin-facing surface to the non-skin-facing surface and disappear from within the surface sheet 16.

[0058] If the first surface of the first fiber layer is the skin-facing surface and a recess that is recessed in the thickness direction is formed on the skin-facing surface, the distance from the skin-facing surface to the water-absorbing fibers included in the second fiber layer is short for the recess. That is, since the water-absorbing fibers that have absorbed body fluid are present at a position close to the skin-facing surface, the body fluid supplied to the skin-facing surface does not migrate in the thickness direction and accumulates in the recess, so the liquid permeability decreases.

[0059] Since the surface sheet 16 of the present embodiment does not have a recess that is recessed in the thickness direction T on the skin-facing surface, the accumulation of body fluid at a specific location is suppressed. Therefore, the surface sheet 16 is excellent in liquid permeability.

[0060] The surface sheet 16 has a uniform basis weight of the second fiber layer 28 in the plane direction. Since the basis weight of the second fiber layer 28 is uniform in the plane direction, the body fluid supplied to the skin-facing surface and migrating in the thickness direction T is uniformly absorbed regardless of the position in the plane direction. Therefore, the surface sheet 16 can obtain excellent liquid drainage properties regardless of the position in the plane direction.

[0061] Since the surface sheet 16 contains 40 mass% or more and 70 mass% or less of water-absorbing fibers in the second fiber layer 28, the body fluid discharged from the wearer is more reliably absorbed by the water-absorbing fibers. Therefore, the surface sheet 16 is excellent in liquid drainage properties when body fluid is repeatedly supplied.

[0062] When the second fiber layer 28 is provided with a third fiber layer 30 made of heat-fusible fibers on the non-skin side, the second fiber layer 28 is covered by the third fiber layer 30, and the exposure of the water-absorbing fibers from the non-skin-facing surface is suppressed. Therefore, the surface sheet 16 suppresses the shedding of the water-absorbing fibers.

[0063] A part of the heat - fusible fibers of the first fiber layer 26 that has entered the second fiber layer 28 may further penetrate the second fiber layer 28, enter the third fiber layer 30, and fuse with a part of the heat - fusible fibers of the third fiber layer 30. That is, a part of the heat - fusible fibers of the first fiber layer 26 bends toward the second fiber layer 28 side in the thickness direction T, enters the second fiber layer 28, and further, a part of it penetrates the second fiber layer 28, enters the third fiber layer 30, and fuses with a part of the heat - fusible fibers of the third fiber layer 30. Therefore, the surface sheet 16 is firmly joined not only between the first fiber layer 26 and the second fiber layer 28 but also between the second fiber layer 28 and the third fiber layer 30, so that delamination can be suppressed.

[0064] The water - absorbent fibers of the second fiber layer 28 are held within the second fiber layer 28 by a part of the heat - fusible fibers of the first fiber layer 26 that are fused with each other and a part of the heat - fusible fibers of the second fiber layer 28, and by a further part of the heat - fusible fibers of the first fiber layer 26 that have penetrated the second fiber layer 28 and a part of the heat - fusible fibers of the third fiber layer 30. Therefore, the surface sheet 16 is further suppressed from having the fibers of the second fiber layer 28 come off.

[0065] A part of the heat - fusible fibers of the second fiber layer 28 may enter the third fiber layer 30 and fuse with a further part of the fusible fibers of the first fiber layer 26 and a part of the heat - fusible fibers of the third fiber layer 30. That is, a part of the heat - fusible fibers of the second fiber layer 28 bends toward the third fiber layer 30 side in the thickness direction T, enters the third fiber layer 30, and in the third fiber layer 30, fuses with a part of the heat - fusible fibers of the third fiber layer 30. Further, it fuses with a further part of the heat - fusible fibers of the first fiber layer 26 that have penetrated the second fiber layer 28 and entered the third fiber layer 30. Therefore, the surface sheet 16 has the second fiber layer 28 and the third fiber layer 30 more firmly joined, so that delamination can be more effectively suppressed.

[0066] The water-absorbent fibers of the second fiber layer 28 are held within the second fiber layer 28 by a part of the heat-fusible fibers of the second fiber layer 28 and a part of the heat-fusible fibers of the third fiber layer 30 that are fused to each other, and by a further part of the heat-fusible fibers of the first fiber layer 26 passing through the second fiber layer 28 and a part of the heat-fusible fibers of the second fiber layer 28 that are fused to each other. Therefore, the surface sheet 16 is further prevented from losing the fibers of the second fiber layer 28.

[0067] (Modification example) The present invention is not limited to the above-described embodiments and can be appropriately modified within the scope of the gist of the present invention. For example, the surface sheet 60 shown in FIG. 5 may have irregularities. That is, the surface sheet 60 has, on the first surface 22, a plurality of convex portions 62 that protrude in a direction from the second surface 24 toward the first surface 22 and are solid, and a plurality of concave portions 64 that are recessed in a direction from the first surface 22 toward the second surface 24. In this specification, "solid" means not having a space with a significantly lower fiber density than the surroundings that hinders the movement of liquid within the convex portion 62. When the difference in height between the highest portion with the highest height of the first surface 22 and the deepest portion with the lowest height of the first surface 22 is d, the portion protruding above the position at a height of d / 2 from the deepest portion can be referred to as the convex portion 62, and the portion recessed downward can be referred to as the concave portion 64. The surface sheet 60 having irregularities may be formed by further passing through a gear processing step after the fourth step in the above manufacturing method. The gear processing step sandwiches a non-woven fabric in which the first fiber layer 26, the second fiber layer 28, and the third fiber layer are joined between a pair of gear processing rolls and locally presses it, thereby forming a plurality of concave portions 64 and obtaining the surface sheet 60. Although not shown, the surface sheet 60 may be provided with squeezing portions. The squeezing portions are intermittently arranged along the longitudinal direction L in the concave portions 64. The squeezing portions may be arranged at equal intervals or non-equal intervals along the longitudinal direction L in the concave portions 64. In the concave portions 64 adjacent to each other in the width direction W, they may be at the same position or different positions in the longitudinal direction L. The squeezing portions are formed by sandwiching from above the first fiber layer 26 and below the third fiber layer 30 arranged with the second fiber layer 28 therebetween in the thickness direction T, and joining the first fiber layer 26, the second fiber layer 28, and the third fiber layer 30.

[0068] The type and use of the absorbent article 10 are not particularly limited. For example, hygiene products and sanitary products such as panty liners, disposable diapers (tape type, pants type), incontinence pads, and sweat-absorbing sheets can be mentioned. These may be targeted at humans or non-human animals such as pets. The liquid to be absorbed by the absorbent article 10 is not particularly limited, and examples include liquid excrement and body fluids of the wearer.

[0069] In the case of the above embodiment, the case where the first fiber layer is disposed on the skin side has been described, but the present invention is not limited thereto. For example, the non-woven fabric may be applied to the surface sheet by disposing the first fiber layer on the non-skin side and disposing the second fiber layer or the third fiber layer on the skin side. That is, the second surface is the skin-facing surface. In this case, the non-woven fabric includes a first fiber layer made of heat-fusible fibers and a second fiber layer including water-absorbent fibers and heat-fusible fibers, so it has a high bulk and excellent liquid permeability. Since the water-absorbent fibers of the second fiber layer are not exposed on the first surface, they are difficult to fall off from the first surface.

[0070] (Measurement method) (Grammage, thickness, fiber density, and fineness of the surface sheet) The grammage, thickness, fiber density, and fineness of the surface sheet in the above embodiment are measured by the following methods. (1) Grammage of the surface sheet: Cut out a sample from the surface sheet to a size that can be appropriately cut out, for example, a size of 10 cm × 10 cm, and measure the mass after leaving it in an atmosphere of 20 ° C and 65% humidity for 24 hours. Divide the measured mass by the area of the sample to calculate the grammage of the sample. The average value of the grammages of 10 samples is taken as the grammage of the surface sheet. (2) Thickness of the surface sheet: 15 cm 2 A thickness gauge (manufactured by Daiei Chemical Precision Instruments Co., Ltd., model FS-60DS) equipped with a measuring head is used to measure the thickness of the surface sheet under the condition of a measuring load of 3 gf / cm 2 (0.3 kPa). Measure the thickness at three locations with one sample, and take the average value of the thicknesses at the three locations as the thickness of the surface sheet. (3) Fiber density of the surface sheet: The fiber density of the surface sheet is calculated by dividing the weight of the surface sheet obtained by the above method by the thickness of the surface sheet obtained by the above method. (4) Fiber fineness: The fiber fineness is calculated from the cross-sectional area of the target fiber measured by magnifying and observing the cross-sectional shape of the fiber using a scanning electron microscope and the specific gravity of the fiber (i.e., the specific gravity of the constituent components of the fiber).

[0071] <Thickness of each part> The thickness of each part of the first fiber layer, the second fiber layer, and the third fiber layer of the surface sheet is measured by the following method. First, the hydrophilic fibers are dyed, and then the thickness of each part is measured. The dyeing of the hydrophilic fibers is performed according to the following procedure. (1) Prepare a surface sheet for which the thickness is to be measured. (2) Put 1 L of water in a pot and heat it to 60°C to 70°C. (3) Put the reagent Kayastain Q (manufactured by Kayaku Shikiso Co., Ltd.) into the pot in (2) and dissolve it. (4) Heat the pot to 80°C. (5) Put the surface sheet into the pot in (4) and leave it for 30 minutes. (5) Then, wash the surface sheet with running water. (6) Dry it in an oven at 80°C for 1 hour. As a result of the above procedure, the water-absorbing fibers (rayon) are dyed blue, and the heat-sealable fibers (PET) are dyed yellow. The thickness measurement is performed according to the following procedure. (1) Cut out a sample from the dyed surface sheet with a length of 5 mm in the machine direction (MD) and a length of 20 mm in the cross direction (CD). (2) Fix the sample to a jig with double-sided tape so that the CD cross-section can be observed. (3) Take a magnified photograph of the cross-section with a digital microscope VHX-7000 manufactured by Keyence Corporation, select the distance between two points for planar measurement, and measure the thickness of each part of the first fiber layer, the second fiber layer, and the third fiber layer of the surface sheet.

[0072] <Content of water-absorbing fibers> The content of the water-absorbent fiber in the second fiber layer can be obtained as follows. (1) After cutting out a sample of the target area from the surface sheet pre-dried at 105°C for 1 hour, measure the initial mass (g) of the sample. (2) Immerse the sample in 70% sulfuric acid for 1 hour to dissolve the water-absorbent fiber. (3) After washing the sample immersed in sulfuric acid with about 6 liters of water while sucking on a Buchner funnel, further wash it with about 1 liter of pure water. (4) After drying the washed sample at 105°C for 2 hours, measure the mass (g) of the sample after treatment. (5) By subtracting the mass of the sample after treatment from the initial mass of the sample, calculate the mass (g) of the water-absorbent fiber contained in the sample, and further, by converting the obtained mass of the water-absorbent fiber contained into the mass per unit planar view area, the content of the water-absorbent fiber can be obtained.

[0073] (Example) A non-woven fabric corresponding to the surface sheet corresponding to the above embodiment was produced and evaluated. The following examples are shown to explain the present invention, but the present invention is not limited to these examples.

[0074] (A) Sample According to the above manufacturing method, using a core-sheath type fiber of PE / PET as the heat-sealable fiber and a fiber formed of rayon as the water-absorbent fiber, a non-woven fabric according to Example 1 including a first fiber layer, a second fiber layer, and a third fiber layer was produced. The flow rates of the first air and the second air in the third step were 5 m 3 / min, and the suction drum pressure was 5.6 kPa. The temperature of the heated air in the fourth step was 136°C. The specific configuration is as shown in Table 1.

[0075] As a comparative example, a non-woven fabric of Comparative Example 2 was produced in the same manner as the above example except that the third step and the fourth step in the above manufacturing method were not performed and the water entanglement method was used.

[0076] Also, as a reference example, a nonwoven fabric of Reference Example 1 was produced in the same manner as in the above Example, except that the third step in the above manufacturing method was not performed. Further, it includes a first fiber layer made of PE / PET core-sheath type fibers, and a second fiber layer including cotton as a water-absorbing fiber and thermoplastic resin fibers of PE / PET core-sheath type fibers. The flow rates of the first air and the second air in the third step in the above manufacturing method were 9 m 3 / min, and an air jet was injected, and a nonwoven fabric of Reference Example 2 having a concavo-convex structure on the first surface was produced by setting the suction drum pressure to 8.6 kPa. The nonwoven fabric of Reference Example 1 was produced by going through the same steps as in the above Example, except that the concavo-convex structure was formed. Microscopic photographs of the cross-section of the obtained nonwoven fabric are shown in FIGS. 6 to 9.

[0077] [Table 1]

[0078] (B) Evaluation method Various tests were conducted according to the following procedure.

[0079] (Liquid permeability and liquid drainage test) (1) A sample cut out to a size of 200 mm × 100 mm and an acrylic plate of the same size as the sample and having a through hole of 40 mm × 10 mm in the center were prepared. (2) The acrylic plate was placed on the center of the surface of the sample on the first fiber layer side. (3) Using a micropipette, 2 ml of horse blood was dropped, and at the same time, a stopwatch was started. (4) The time (permeation time) until the horse blood disappeared from the sample and around the hole of the acrylic plate was measured. (5) Subsequently, the time (liquid drainage time) until the horse blood in the acrylic plate drained was measured. (6) 30 seconds after the start of the measurement, 2 ml of horse blood was dropped for the second time (the second measurement was started even if the first horse blood had not completely drained). (7) The measurements in (4) and (5) above were performed in order. (8) Remove the acrylic plate 60 seconds after the start of measurement, and place 10 filter papers (35 mm × 50 mm) whose weights have been measured in advance and a weight (35 mm × 50 mm, 525 g) on the place where the horse blood was dropped 90 seconds after the start of measurement. (9) Remove the weight 60 seconds later and measure the weight of the filter paper.

[0080] (10) Subtract the mass of the filter paper before placement from the mass of the filter paper after placement on the sample to obtain the rewet (g), and calculate the ratio (%) to the amount of horse blood absorbed (2 ml ≒ 2 g).

[0081] (Fiber shedding test) (1) Dry the membrane filter in an oven at 90 °C for 1 hour, and then let it cool in a desiccator for 30 minutes. (2) Prepare 5 samples cut into a size of 100 mm × 100 mm. (3) Prepare 5 300-ml beakers each containing 300 ml of tap water. (4) Place a rotor in the beaker and stir with a magnetic stirrer. (5) Fold the sample into an inverted conical shape with the smoother surface facing outwards. (6) Gently drop the sample in (5) into the center of the water surface in the beaker, and start the stopwatch when the sample touches the center of the water surface. (7) After stirring for 10 minutes, take out the sample. (4) to (7) are performed for each sample. (8) Measure the weight of the membrane filter in (1). (9) Place the membrane filter on the suction flask, place the funnel on it and fix it with a holder. (10) Pour ethanol into the funnel to wet the membrane filter, turn on the switch of the vacuum pump and suck. (11) Pour the water in the stirred beaker into the funnel and suck. (12) When the water in the stirred beaker can be sucked, first remove the hose connected to the suction flask and turn off the switch of the vacuum pump. (13) Remove the funnel and take out the membrane filter with fibers accumulated in a petri dish. Cover the petri dish with a wrap so that air can enter, and write the time on the wrap. (15) The membrane filter in (14) was dried in an oven at 90 °C for 1 hour, allowed to cool in a desiccator for 30 minutes, and then weighed. The operations in (9) to (15) were performed for each sample. (16) The average value of the measured weights (n = 5) was taken as the amount of fiber shedding (mg / m 2 ).

[0082] (C) Evaluation Results As shown in Table 1, for the nonwoven fabric according to Example 1, excellent results were obtained both for the first and second times in terms of liquid permeability and liquid drainage. Also, it was confirmed that the nonwoven fabric according to Example 1 is excellent in rewetting property.

[0083] The nonwoven fabric according to Comparative Example 1 is produced by the water entanglement method, so it has a low bulk density, resulting in poor liquid permeability, and since the water-absorbing fibers are present on the surface, it is considered that the liquid drainage property is poor.

[0084] In Reference Example 1, compared with Example 1, the liquid drainage property and rewetting property were inferior, and the amount of fiber shedding was large. The nonwoven fabric according to Reference Example 1 did not perform the third step in the manufacturing method of the above embodiment, so it is considered that the liquid could not smoothly transfer from the first fiber layer to the second fiber layer. Also, in the nonwoven fabric of Reference Example 1, since the water-absorbing fibers are difficult to be retained in the second fiber layer, it is considered that the amount of fiber shedding increased.

[0085] For the nonwoven fabric according to Reference Example 2, by jetting an air jet to form an uneven structure on the first surface, it is considered that the liquid easily accumulates in the concave portions, resulting in inferior liquid permeability and liquid drainage properties.

Explanation of Reference Signs

[0086] 10 Absorbent article 12 Body part 14 Flap part 16 Surface sheet (nonwoven fabric) 18 Absorbent body 20 Back sheet 22 First surface (muscle-facing surface) 24 Second surface (non-muscle-facing surface) 40 Laminated web 42 Suction drum 44 Inner cylinder 46 Outer cylinder 48 Suction area 54 Dryer 60 Surface sheet 62 Protrusion 64 Recess CD Crossing direction MD Machine direction L Longitudinal direction T Thickness direction W Width direction

Claims

1. A non-woven fabric for absorbent articles, comprising a first fiber layer and a second fiber layer in order in the thickness direction, wherein the first fiber layer has a first surface and is made of heat-fusible fibers, the second fiber layer contains water-absorbent fibers and heat-fusible fibers, a part of the heat-fusible fibers of the first fiber layer penetrates into the second fiber layer and is fused with a part of the heat-fusible fibers of the second fiber layer, the water-absorbent fibers of the second fiber layer are not exposed on the first surface, and the first fiber layer has no recess formed in the thickness direction on the first surface. A non-woven fabric.

2. The non-woven fabric according to claim 1, further comprising a third fiber layer made of heat-fusible fibers on the side of the second fiber layer opposite to the first fiber layer.

3. A further part of the heat-fusible fibers of the part of the first fiber layer that has penetrated into the second fiber layer penetrates through the second fiber layer, enters the third fiber layer, and is fused with a part of the heat-fusible fibers of the third fiber layer. The non-woven fabric according to claim 2.

4. A part of the heat-fusible fibers of the second fiber layer penetrates into the third fiber layer and is fused with a further part of the fusible fibers of the first fiber layer and a part of the heat-fusible fibers of the third fiber layer. The non-woven fabric according to claim 3.

5. The non-woven fabric according to claim 1, wherein the first surface of the first fiber layer is the skin-facing surface.

6. The non-woven fabric according to claim 5, wherein the basis weight of the second fiber layer is uniform in the plane direction.

7. The non-woven fabric according to claim 5, wherein the second fiber layer contains 40% by mass or more and 70% by mass or less of the water-absorbent fibers.

8. A first step of injecting gas from the first fiber web side to a first fiber web made of heat-fusible fibers and a second fiber web containing water-absorbent fibers and heat-fusible fibers, which are stacked in order in the thickness direction, and a second step of melting the surfaces of the heat-fusible fibers of the first fiber web and the heat-fusible fibers of the second fiber web and fusing the heat-fusible fibers together. The method for manufacturing a non-woven fabric for absorbent articles, wherein in the first step, the gas is injected from a plurality of nozzles arranged in the width direction at a flow rate of 3 to 5 m3 / min under the condition that the movement amount in the thickness direction is larger than the movement amount in the width direction orthogonal to the machine direction of the heat-fusible fibers of the first fiber web.

9. The method for manufacturing a nonwoven fabric for an absorbent article according to claim 8, wherein in the first step, a first fiber web and a second fiber web stacked in order in the thickness direction are placed on the peripheral surface of a suction drum having a suction drum pressure of 5 to 9 kPa, and the gas is injected.

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