Non-woven fabric for absorbent article and method for producing non-woven fabric

Abstract

Provided is a non-woven fabric for an absorbent article, said non-woven fabric being capable of suppressing interlayer peeling and having excellent liquid permeability and liquid discharge properties. A non-woven fabric (16) for an absorbent article is provided with, in order in the thickness direction (T), a first fiber layer (26) that has a first surface (22) and is formed from heat-fusible fibers, and a second fiber layer (28) that contains water-absorbent fibers and heat-fusible fibers, a part of the heat-fusible fibers of the first fiber layer (26) entering the second fiber layer (28), and the heat-fusible fibers of the second fiber layer (28) entering the first surface (22). The second fiber layer (28) is welded to a portion of the second fiber layer (28) by means of the heat-fusible fibers, and the water-absorbent fibers of the second fiber layer (28) are not exposed on the first surface (22).

Description

Technical Field

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

[0002] As a nonwoven fabric for absorbent articles, for example, a composite nonwoven fabric is disclosed in Patent Document 1, which is characterized in that it is formed by stacking a cotton web and a synthetic staple fiber web containing thermally adhesive staple fibers, and the constituent fibers of the cotton web, the constituent fibers of the cotton and synthetic staple fiber web, and the constituent fibers of the synthetic staple fiber web are three-dimensionally interwoven and integrated with each other, and the intersections of the fibers are thermally bonded by welding of the thermal adhesive component.

[0003] In addition, patent document 2 discloses a nonwoven fabric for absorbent articles, which includes a first fiber layer and a second fiber layer located on a main surface of the first fiber layer, the first fiber layer contains a first core-sheath type composite fiber, the second fiber layer contains a second core-sheath type composite fiber and cellulose fibers, the fineness of the first core-sheath type composite fiber is smaller than the fineness of the second core-sheath type composite fiber, the fineness of the first core-sheath type composite fiber is 1.0 dtex to 2.8 dtex, the fineness of the second core-sheath type composite fiber is 1.7 dtex to 5.6 dtex, the fineness of the cellulose fiber is 1.2 dtex to 6.0 dtex, and the second fiber layer contains cellulose fibers in a proportion of 5 mass % to 40 mass % based on the total mass of the second fiber layer.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 11-229256

[0007] Patent Document 2: Japanese Patent Application Publication No. 2020-171688 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The nonwoven fabric of Patent Document 1 is subjected to high-pressure fluid treatment on the stacked webs, so that the constituent fibers of the cotton web, the constituent fibers of the cotton and synthetic staple fiber webs, and the constituent fibers of the synthetic staple fiber webs are three-dimensionally interwoven and integrated. Since the web is subjected to a large force in the thickness direction due to the high-pressure fluid, the bulkiness of the nonwoven fabric is reduced. When the nonwoven fabric is used as a surface sheet of an absorbent article, it is difficult for liquid to pass through in the thickness direction, and the liquid permeability is poor.

[0010] Patent Document 2 states that: In order to easily obtain a nonwoven fabric with a good touch, it is preferred to join the first fiber layer and the second fiber layer by a hot air method (hot air through heat treatment method), but there is a problem that since the fibers of the first fiber layer and the second fiber layer have fewer contact points with each other, there are fewer welded parts, and it is easy to peel between the first fiber layer and the second fiber layer. The more cellulose fibers the second fiber layer contains, the fewer welded parts there are in the first fiber layer and the second fiber layer, and therefore it is easier to peel between the first fiber layer and the second fiber layer.

[0011] An object of the present invention is to provide a nonwoven fabric for an absorbent article which can suppress interlayer delamination and has excellent liquid permeability, and a method for producing a nonwoven fabric for an absorbent article.

[0012] Solutions for solving problems

[0013] The present invention is a nonwoven fabric for absorbent articles, which comprises a first fiber layer and a second fiber layer in sequence in the thickness direction, wherein the first fiber layer has a first surface and is formed of heat-fusible fibers, and the second fiber layer contains absorbent fibers and heat-fusible fibers, a portion of the heat-fusible fibers in the first fiber layer enters the second fiber layer and is fused to a portion of the heat-fusible fibers in the second fiber layer, and the absorbent fibers in the second fiber layer are not exposed on the first surface.

[0014] The present invention is a method for manufacturing a nonwoven fabric for absorbent articles, wherein the method for manufacturing a nonwoven fabric for absorbent articles comprises the following steps: a first step, in which gas is sprayed from the side of a first fiber web formed of heat-fusible fibers to the first fiber web and a second fiber web including absorbent fibers and heat-fusible fibers that are overlapped in sequence in the thickness direction; and a second step, in which the surfaces of the heat-fusible fibers of the first fiber web and the surfaces of the heat-fusible fibers of the second fiber web are melted to weld the heat-fusible fibers to each other, and in the first step, the gas is sprayed under the condition that the amount of movement of the heat-fusible fibers of the first fiber web in the thickness direction is greater than the amount of movement in the width direction orthogonal to the machine direction.

[0015] Effects of the Invention

[0016] The nonwoven fabric for absorbent articles according to the present invention can suppress interlayer delamination and has excellent liquid permeability. The method for producing a nonwoven fabric for absorbent articles according to the present invention can obtain a nonwoven fabric that can suppress interlayer delamination and has excellent liquid permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a figure which shows schematically the absorbent article which concerns on embodiment.

[0018] Figure 2 is a schematic representation of the Figure 1 End view of the cross section taken along line II-II.

[0019] Figure 3 It is a partial enlarged cross-sectional view of the surface piece.

[0020] Figure 4 It is a schematic diagram which shows the manufacturing process of the nonwoven fabric of this embodiment.

[0021] Figure 5 This is a partially enlarged cross-sectional view schematically showing a nonwoven fabric according to a modified example.

[0022] Figure 6 This is a microscope photograph of a cross section of the nonwoven fabric of Example 1.

[0023] Figure 7 This is a microscope photograph of a cross section of the nonwoven fabric of Comparative Example 1.

[0024] Figure 8 This is a microscope photograph of a cross section of the nonwoven fabric of Comparative Example 2.

[0025] Fig. 9 This is a microscope photograph of a cross section of the nonwoven fabric of Reference Example 1. DETAILED DESCRIPTION

[0026] The embodiments of the present invention relate to the following aspects.

[0027] [Method 1]

[0028] A nonwoven fabric for an absorbent article, comprising a first fiber layer and a second fiber layer in this order in the thickness direction, wherein:

[0029] The first fiber layer has a first surface and is formed of heat-fusible fibers.

[0030] The second fiber layer includes water-absorbent fibers and thermally fusible fibers.

[0031] A portion of the heat-fusible fibers in the first fiber layer enters the second fiber layer and is fused to a portion of the heat-fusible fibers in the second fiber layer, and the water-absorbent fibers in the second fiber layer are not exposed on the first surface.

[0032] In the nonwoven fabric, a portion of the heat-fusible fibers of the first fiber layer and a portion of the heat-fusible fibers of the second fiber layer are fused to each other. That is, a portion of the heat-fusible fibers of the first fiber layer enters the second fiber layer, contacts and fuses with a portion of the heat-fusible fibers included in the second fiber layer. Therefore, in the nonwoven fabric, the first fiber layer and the second fiber layer are firmly bonded, so that interlayer delamination between the first fiber layer and the second fiber layer can be suppressed.

[0033] The water-absorbent fibers of the second fiber layer are held in the second fiber layer by the heat-fusible fibers of the first fiber layer and 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 not easily detached from the first surface. Therefore, in the nonwoven fabric, the fibers of the second fiber layer can be prevented from detaching.

[0034] When the nonwoven fabric is used as a surface sheet of an absorbent article and the first surface is used as the skin-facing surface, the body fluid supplied to the skin-facing surface is transferred from the skin-facing surface to the inside of the first fiber layer. In addition, when the second surface is used as the skin-facing surface, the body fluid supplied to the skin-facing surface is transferred from the skin-facing surface to the inside of the second fiber layer. Since the nonwoven fabric includes the first fiber layer formed of thermally fusible fibers and the second fiber layer including water-absorbent fibers and thermally fusible fibers, it has high bulkiness and excellent liquid permeability.

[0035] As a result, in the nonwoven fabric, interlayer delamination between the first fiber layer and the second fiber layer can be suppressed, and the nonwoven fabric has excellent liquid permeability.

[0036] [Method 2]

[0037] The nonwoven fabric according to aspect 1, wherein the first fiber layer does not have a recessed portion recessed in the thickness direction formed on the first surface.

[0038] If a concave portion depressed in the thickness direction is formed on the first surface, the bulkiness of this portion is low, so the liquid permeability decreases.

[0039] In contrast, the nonwoven fabric of the present invention does not have a recessed portion depressed in the thickness direction formed on the first surface, thereby preventing body fluid from accumulating in a specific location. Therefore, the nonwoven fabric has excellent liquid permeability.

[0040] [Method 3]

[0041] The nonwoven fabric according to aspect 1 or 2, further comprising a third fiber layer formed of thermally fusible fibers on the side of the second fiber layer opposite to the first fiber layer.

[0042] 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 is the second surface. The second fiber layer is covered by the third fiber layer, and the water-absorbent fibers are prevented from being exposed from the second surface. Therefore, in the nonwoven fabric, the water-absorbent fibers can be prevented from being detached.

[0043] [Method 4]

[0044] The nonwoven fabric according to the third aspect, wherein another part of the heat-fusible fibers of the first fiber layer that enter the second fiber layer penetrates the second fiber layer, enters the third fiber layer, and is fused to the heat-fusible fibers of the third fiber layer.

[0045] In the nonwoven fabric, another part of the heat-fusible fibers of a part of the first fiber layer is fused to another part of the heat-fusible fibers of a part of the third fiber layer. That is, another part of the heat-fusible fibers of a part of the first fiber layer enters the second fiber layer, and another part of the heat-fusible fibers of a part of the first fiber layer penetrates the second fiber layer, enters the third fiber layer, and is fused to another part of the heat-fusible fibers of the third fiber layer. Therefore, in the nonwoven fabric, in addition to the first fiber layer and the second fiber layer being firmly bonded, the second fiber layer and the third fiber layer are also firmly bonded, so that interlayer delamination can be suppressed.

[0046] The water-absorbent fibers of the second fiber layer are held in the second fiber layer by a portion of the heat-fusible fibers of the first fiber layer and a portion of the heat-fusible fibers of the second fiber layer that are fused to each other, and another portion of the heat-fusible fibers of the first fiber layer that penetrate the second fiber layer and a portion of the heat-fusible fibers of the third fiber layer. Therefore, in the nonwoven fabric, the fibers of the second fiber layer can be further prevented from falling off.

[0047] [Method 5]

[0048] The nonwoven fabric according to aspect 4, wherein a part of the heat-fusible fibers in the second fiber layer enters the third fiber layer and is fused to another part of the heat-fusible fibers in the first fiber layer and a part of the heat-fusible fibers in the third fiber layer.

[0049] A portion of the heat-fusible fibers of the second fiber layer enters the third fiber layer, is fused to a portion of the heat-fusible fibers of the third fiber layer in the third fiber layer, and is further fused to another portion of the heat-fusible fibers of the first fiber layer that penetrate the second fiber layer and enter the third fiber layer. Therefore, in the nonwoven fabric, the second fiber layer and the third fiber layer are more firmly bonded, and interlayer delamination can be further suppressed.

[0050] The water-absorbent fibers of the second fiber layer are held in the second fiber layer by a portion of the heat-fusible fibers of the second fiber layer and a portion of the heat-fusible fibers of the third fiber layer being fused to each other, and another portion of the heat-fusible fibers of the first fiber layer penetrating the second fiber layer and a portion of the heat-fusible fibers of the second fiber layer. Therefore, in the nonwoven fabric, the fibers of the second fiber layer can be further prevented from falling off.

[0051] [Method 6]

[0052] The nonwoven fabric according to any one of aspects 1 to 5, wherein the first surface of the first fiber layer is a skin-facing surface.

[0053] When the nonwoven fabric is used as a surface sheet of an absorbent article and the first surface is used as the skin-opposing surface, the body fluid supplied to the skin-opposing surface is transferred from the skin-opposing surface to the inside of the first fiber layer. Since the absorbent fibers are not exposed on the skin-opposing surface, the body fluid is not easy to remain on the skin-opposing surface. The body fluid transferred to the inside of the first fiber layer is further transferred in the thickness direction and reaches the interface between the first fiber layer and the second fiber layer. The body fluid enters the second fiber layer through a part of the heat-fusible fibers of the first fiber layer and smoothly transfers to the second fiber layer. The body fluid transferred to the second fiber layer is absorbed by the absorbent fibers contained in the second fiber layer. When the nonwoven fabric is used as a surface sheet of an absorbent article, the body fluid absorbed by the absorbent fibers is absorbed by the absorbent body arranged on the non-skin side. In this way, in the nonwoven fabric, the body fluid supplied to the skin-opposing surface is smoothly transferred from the first fiber layer to the second fiber layer and absorbed by the absorbent fibers of the second fiber layer, so the drainage is excellent.

[0054] [Method 7]

[0055] The nonwoven fabric according to aspect 6, wherein the basis weight of the second fiber layer is uniform in the plane direction.

[0056] Since the weight per unit area of ​​the second fiber layer is uniform in the surface direction, the body fluid supplied to the skin-opposite surface and transferred in the thickness direction is uniformly absorbed regardless of the position in the surface direction. Therefore, in the nonwoven fabric, excellent liquid discharge can be obtained regardless of the position in the surface direction.

[0057] [Method 8]

[0058] 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-absorbent fiber.

[0059] Since the nonwoven fabric contains 40% to 70% by mass of absorbent fibers in the second fiber layer, the absorbent fibers more reliably absorb body fluids discharged from the wearer. Therefore, the nonwoven fabric has excellent liquid discharge properties when repeatedly supplied with body fluids.

[0060] [Method 9]

[0061] A method for producing a nonwoven fabric for an absorbent article, wherein:

[0062] The method for manufacturing the nonwoven fabric for the absorbent article comprises the following steps:

[0063] a first step of jetting gas from a first fiber web formed of thermally fusible fibers toward the first fiber web and a second fiber web including water-absorbent fibers and thermally fusible fibers sequentially stacked in a thickness direction; and

[0064] a second step in which the surfaces of the heat-bonding fibers of the first fiber web and the surfaces of the heat-bonding fibers of the second fiber web are melted to fuse the heat-bonding fibers to each other;

[0065] In the first step, the gas is ejected under the condition that the amount of movement of the thermally fusible fibers in the first fiber web in the thickness direction is larger than the amount of movement in the width direction orthogonal to the machine direction.

[0066] In the first step of jetting gas from the first fiber web formed of heat-fusible fibers to the first fiber web and the second fiber web containing absorbent fibers and heat-fusible fibers which overlap in the thickness direction, the gas is jetted under the condition that the amount of movement of the heat-fusible fibers in the thickness direction of the first fiber web is greater than the amount of movement in the width direction orthogonal to the machine direction, so that the nonwoven fabric of the embodiment 1 can be formed. That is, the present manufacturing method can form a nonwoven fabric, which is a nonwoven fabric for absorbent articles, and has a first fiber layer and a second fiber layer in order in the thickness direction, wherein the first fiber layer is formed of heat-fusible fibers and has a first surface, the second fiber layer contains absorbent fibers and heat-fusible fibers, a part of the heat-fusible fibers of the first fiber layer enters the second fiber layer and is fused to the heat-fusible fibers of the second fiber layer, and the absorbent fibers of the second fiber layer are not exposed on the first surface.

[0067] Hereinafter, the nonwoven fabric for absorbent articles according to the embodiment will be described in detail with reference to the drawings.

[0068] (Structure of absorbent article)

[0069] Figure 1 1 is a diagram schematically showing an absorbent article 10 according to an embodiment. Figure 2 is a schematic representation of the Figure 1 A cross-sectional view of the cross section of line II-II, Figure 3 It is a partial enlarged cross-sectional view of the surface piece.

[0070] Figure 1 The absorbent article 10 shown 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 includes a main body 12 extending along the longitudinal direction L and a pair of wing portions 14 extending from the approximate center in the longitudinal direction L to both sides in the width direction W. Since the longitudinal direction L, the width direction W, and the thickness direction T of the absorbent article 10 coincide with the longitudinal direction L, the width direction W, and the thickness direction T of each component described later, the longitudinal direction L, the width direction W, and the thickness direction T are commonly used for the absorbent article 10 and its components hereinafter. The "skin-opposing surface side" refers to a side that is relatively close to the skin surface of the wearer in the thickness direction T when the absorbent article 10 is worn by the wearer of the absorbent article 10, and the "non-skin-opposing surface side" refers to a side that is relatively far from the skin surface of the wearer in the thickness direction T when the absorbent article 10 is worn by the wearer of the absorbent article 10, and the "skin-opposing surface side" and the "non-skin-opposing surface side" are commonly used for each component of the absorbent article 10. In this specification, there is a situation where the "surface on the skin-opposing side" of the absorbent article 10 and each component constituting the absorbent article 10 (such as the surface sheet, absorbent body, back sheet, etc.) is referred to as the "skin-opposing side", and their "surface on the non-skin-opposing side" is referred to as the "non-skin-opposing side".

[0071] like Figure 2 As shown, the absorbent article 10 has a surface sheet 16, an absorbent body 18 and a back sheet 20 in order from the skin-opposite side in the thickness direction T. The surface sheet 16 is a liquid-permeable sheet located on the skin-opposite side of the wearer. The absorbent body 18 is a liquid-absorbent and liquid-retaining component located between the surface sheet 16 and the back sheet 20. As materials constituting the absorbent body 18, pulp fibers, synthetic fibers, absorbent polymers, etc. can be cited. The back sheet 20 is a liquid-impermeable sheet located on the non-skin-opposite side of the wearer. As the back sheet 20, for example, any liquid-impermeable sheet such as a liquid-impermeable nonwoven fabric, a synthetic resin film, their composite sheets, and an SMS nonwoven fabric can be cited. An outer sheet (not shown) that strengthens the back sheet 20 and improves the feel can also be stacked on the non-skin-opposite side of the back sheet 20. As an outer sheet, any waterproof sheet such as a component identical to the back sheet 20, a waterproof nonwoven fabric, a synthetic resin film, their composite sheets, etc. can be cited. The absorber 18, the top sheet 16, and the back sheet 20 are bonded together with adhesives. As the adhesives for bonding the top sheet 16, the absorber 18, and the back sheet 20, known materials commonly used in absorbent articles 10, such as thermoplastic adhesives, can be used.

[0072] (Surface Sheet)

[0073] Below, refer to Figure 3 The surface sheet 16 is described. The surface sheet 16 is formed by the nonwoven fabric of the present embodiment. The surface sheet 16 has a length direction L, a width direction W, and a thickness direction T, and has a first surface 22 on one side and a second surface 24 on the opposite side of the first surface 22. The first surface 22 and the second surface 24 intersect with the thickness direction T, respectively. The first surface 22 and the second surface 24 of the present embodiment are respectively substantially flat. One direction in the thickness direction T is set to face upward, and the other direction is set to face downward.

[0074] The surface sheet 16 is provided with a first fiber layer 26 and a second fiber layer 28 in sequence along the thickness direction T. The first fiber layer 26 is formed of heat-fusible fibers and has a first surface 22 that is the skin-opposite surface of the surface sheet 16 (liquid-permeable sheet). The type of nonwoven fabric of the surface sheet 16 is not particularly limited as long as it can be used as an absorbent article, but it is preferably a thermally bonded nonwoven fabric in which heat-fusible fibers are fused to each other, and more preferably a hot air nonwoven fabric. The thickness of the surface sheet 16 can be, for example, 0.5 mm to 3.0 mm.

[0075] The basis weight of the first fiber layer 26 is substantially uniform in the surface direction, and can be, for example, 6 g / m 2 ~200g / m 2 . The heat-fusible fibers included in the first fiber layer 26 include: fibers formed of thermoplastic resins, such as olefin resins such as polyethylene (PE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA); polyester resins such as polyethylene terephthalate (PET) and polylactic acid (PLA); well-known resins such as polyamide resins such as nylon 6, and these resins can be used alone or in combination of two or more resins. The structure of the fibers formed of such thermoplastic resins is not particularly limited, and examples thereof include: composite fibers such as core-sheath fibers of PET / PE, parallel fibers, and island-type fibers; hollow fibers; flat, Y-shaped, C-shaped, and other special-shaped cross-section fibers, and the fibers having these structures can be used alone or in combination of two or more fibers. As the fineness of the heat-fusible fibers, for example, 1 dtex to 20 dtex can be cited.

[0076] The second fiber layer 28 includes absorbent fibers and heat-bondable fibers and has a second surface 24 that is the non-skin facing surface of the top sheet 16. The second fiber layer 28 preferably includes 40 to 60% by mass of absorbent fibers.

[0077] The weight per unit area of ​​the second fiber layer 28 is substantially uniform in the surface direction, and can be, for example, 6 g / m 2 ~200g / m 2The absorbent fibers included 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 cuprammonium, etc. These cellulose fibers may be used alone or in combination of two or more. The fineness of the absorbent fibers may be, for example, 0.5 dtex to 5.0 dtex.

[0078] The heat-fusible fibers included 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. The fineness of the thermoplastic resin fibers included in the second fiber layer 28 may be, for example, 1 dtex to 20 dtex. The fiber diameter of the heat-fusible fibers included in the second fiber layer 28 may be the same as or different from the fiber diameter of the heat-fusible fibers included in the first fiber layer 26.

[0079] The surface sheet 16 may also include a third fiber layer 30 formed of heat-fusible fibers on the second surface 24 side. That is, the surface sheet 16 may include a first fiber layer 26, a second fiber layer 28, and a third fiber layer 30 in the thickness direction T. The third fiber layer 30 may also use the same material as the first fiber layer 26. The weight per unit area of ​​the third fiber layer 30 is approximately uniform in the surface direction, and for example, 6 g / m 2 ~200g / m 2 The third fiber layer 30 can be configured to have the same structure as the first fiber layer 26. The surface of the third fiber layer 30 on the skin-facing side is in contact with the second fiber layer 28. When the top sheet 16 includes the third fiber layer 30, the surface of the third fiber layer 30 on the non-skin-facing side becomes the non-skin-facing side of the top sheet 16, i.e., the second surface 24.

[0080] The boundary between the first fiber layer 26 and the second fiber layer 28 and the boundary between the second fiber layer 28 and the third fiber layer 30 can be defined by the presence or absence of absorbent fibers. That is, in the cross section of the surface sheet 16, the upper end in the thickness direction T where the absorbent fibers exist is set as the boundary between the first fiber layer 26 and the second fiber layer 28, the side where the absorbent fibers exist is set as the second fiber layer 28, and the side where the absorbent fibers do not exist is set as 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 absorbent fibers exist is set as the boundary between the second fiber layer 28 and the third fiber layer 30, the side where the absorbent fibers exist is set as the second fiber layer 28, and the side where the absorbent fibers do not exist is set as the third fiber layer 30. The boundary between the first fiber layer 26 and the second fiber layer 28 and the boundary between the second fiber layer 28 and the third fiber layer 30 defined in this way are Figure 3The fiber is linear in shape, but the present invention is not limited thereto, and may have slight undulations in the thickness direction T. The water-absorbent fiber is dyed by a method described later so as to be visually recognizable.

[0081] The thickness of the first fiber layer 26, i.e., 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 mm to 2.0 mm. The skin-facing surface of the first fiber layer 26 (the first surface 22 of the nonwoven fabric) does not form a recessed portion that is recessed in the thickness direction T. The recess in this specification refers to a recess that is intentionally formed by bending or moving the fibers by performing gear processing, spraying air jets, etc., and does not include undulations that are naturally formed by simply arranging the stacked fibers. In 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 of the maximum height. The thickness of the second fiber layer 28, i.e., 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 mm 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 mm to 0.5 mm.

[0082] A portion of the heat-fusible fibers of the first fiber layer 26 are fused to a portion of the heat-fusible fibers of the second fiber layer 28 in the second fiber layer 28. That is, a portion of the heat-fusible fibers of the first fiber layer 26 are bent toward the second fiber layer 28 in the thickness direction T, enter the second fiber layer 28, and come into contact with and fuse to a portion of the heat-fusible fibers included in the second fiber layer 28.

[0083] Another part of the heat-fusible fibers of the first fiber layer 26 that enter the second fiber layer 28 is fused to another part of the heat-fusible fibers of the third fiber layer 30 in the third fiber layer 30. That is, another part of the heat-fusible fibers of the first fiber layer 26 bends toward the second fiber layer 28 in the thickness direction T and enters the second fiber layer 28, and another part of the heat-fusible fibers penetrates the second fiber layer 28, enters the third fiber layer 30, and contacts and fuses with another part of the heat-fusible fibers of the third fiber layer 30.

[0084] A portion of the heat-fusible fibers of the second fiber layer 28 are fused to a portion of the heat-fusible fibers of the third fiber layer 30 in the third fiber layer 30. That is, a portion of the heat-fusible fibers of the second fiber layer 28 are bent toward the third fiber layer 30 in the thickness direction T, enter the third fiber layer 30, and come into contact with and fuse to a portion of the heat-fusible fibers included in the third fiber layer 30.

[0085] (Manufacturing method)

[0086] Below, refer to Figure 4 A method for manufacturing the top sheet 16 will be described. Figure 4 2 is a schematic diagram showing a manufacturing process of the top sheet 16 having the first fiber layer 26 and the second fiber layer 28. The top sheet 16 is manufactured through the first step, the second step, the third step, and the fourth step. Figure 4 Here, MD refers to the machine direction (conveying direction).

[0087] In the first step, the heat-fusible fibers and the water-absorbent fibers are supplied to the first carding machine 32 to form the second fiber web 34. In the second step, the heat-fusible fibers are supplied to the second carding machine 36 to form the first fiber web 38. The first fiber web 38 is superimposed on the second fiber web 34 to obtain a laminated web 40. The laminated web 40 is conveyed to the third step.

[0088] In the third step, the stacked web 40 is first placed on the circumference of the suction drum 42. The suction drum 42 has an inner drum 44 in a fixed state and an outer drum 46 with air permeability that rotates in the machine direction MD and is concentric with the inner drum 44. The suction drum pressure obtained by measuring the pressure in the suction drum with a pressure gauge can be appropriately selected according to the unit area weight of each fiber web, the flow rate of the first air and the flow rate of the second air described later, but is preferably 5 kPa to 9 kPa, and more preferably 5 kPa to 8 kPa. The stacked web 40 is placed on the circumference of the outer drum 46 and is conveyed in the machine direction MD at a predetermined speed, for example, 100 m / min, together with the outer drum 46. The inner drum 44 has a suction area 48. Above the suction area 48, there are provided: a first manifold 50 having a plurality of nozzles arranged in a 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. The nozzle has a predetermined opening diameter, for example, 1 mm. The first manifold 50 sprays the first air formed by, for example, heated gas at 200° C. toward the laminated web 40. The flow rate of the first air sprayed from the first manifold 50 is, for example, 3 m / s. 3 / min~5m 3 Next, the second manifold 52 sprays the second air formed of, for example, 200° C. heated gas toward the laminated web 40. The flow rate of the second air sprayed from the second manifold 52 is, for example, 3 m / min. 3 / min~5m 3 / min.

[0089] By sequentially spraying the first air and the second air onto the laminated web 40, the heat-fusible fibers of the first fiber web 38 located directly below the first manifold 50 and the second manifold 52 are moved. The flow rate of the first air and the second air is 3 m / s. 3 / min~5m 3 / min, so that the movement amount of the heat-fusible fibers of the first fiber web 38 in the thickness direction T is larger than the movement amount in the width direction W (cross direction CD). In other words, the first air and the second air are sprayed under the condition that the movement amount in the thickness direction T is larger than the movement amount 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 side in the thickness direction T and enters the second fiber web 34.

[0090] By spraying the first air and the second air under the above-mentioned predetermined conditions, the surface of the first fiber web 38 moves less in the width direction W and moves in a pressed manner in the thickness direction T, so that the entire surface structure can be smoother with fewer bumps. Therefore, the first fiber layer 26 based on the first fiber web can be arranged on the skin side to form the surface sheet 16.

[0091] In the fourth step, the laminated web 40 passes through the dryer 54. The dryer 54 blows heated air at a temperature of, for example, 120° C. to 150° C., which can melt the surface of the heat-fusible fibers, to the laminated web 40. The heat-fusible fibers of the laminated web 40 are fused to each other. As described above, a part of the heat-fusible fibers of the first fiber web 38 enters the second fiber web 34, and thus are fused to a part of the heat-fusible fibers contained in the second fiber web 34 in the second fiber web 34.

[0092] The laminated web 40 conveyed from the dryer 54 is cooled to room temperature to obtain the top sheet 16 that can be used as an absorbent article. Since the top sheet (nonwoven fabric) 16 obtained as described above is a hot air nonwoven fabric, it has excellent bulkiness.

[0093] The top sheet 16 having the third fiber layer 30 is formed by supplying heat-fusible fibers to a carding machine (not shown) before the first step to form a third fiber web, on which the second fiber web 34 formed in the first step is overlapped, and further overlapped with the first fiber web 38 formed in the second step, thereby forming a laminated web. By subjecting the laminated web to the third and fourth steps, the top sheet 16 having the first fiber layer 26, the second fiber layer 28, and the third fiber layer 30 is obtained.

[0094] (Function and Effect)

[0095] The absorbent article 10 is worn by placing the surface sheet 16 on the side opposite to the skin of the wearer. The body fluid discharged from the wearer is supplied to the surface sheet 16. The body fluid is transferred from the first surface 22 to the first fiber layer 26 in the thickness direction T. The body fluid is further introduced into the interior from the first fiber layer 26 by the absorbent fibers of the second fiber layer 28, and a part of it is absorbed by the absorbent fibers. The body fluid introduced and absorbed by the absorbent fibers is absorbed by the surface sheet 16 and the absorbent body 18 arranged on the non-skin side.

[0096] The surface sheet 16 is a surface sheet for an absorbent article, and comprises a first fiber layer 26 and a second fiber layer 28 in sequence in the thickness direction T, wherein the first fiber layer 26 has a skin-opposing surface and is formed of heat-fusible fibers, and the second fiber layer 28 comprises absorbent fibers and heat-fusible fibers, a portion of the heat-fusible fibers of the first fiber layer 26 enters the second fiber layer 28 and is fused with a portion of the heat-fusible fibers of the second fiber layer 28, and the absorbent fibers of the second fiber layer 28 are not exposed on the skin-opposing surface.

[0097] In the top sheet 16, a portion of the heat-fusible fibers of the first fiber layer 26 and a portion of the heat-fusible fibers of the second fiber layer 28 are fused to each other. That is, a portion of the heat-fusible fibers of the first fiber layer 26 are bent toward the second fiber layer 28 in the thickness direction T, enter the second fiber layer 28, and contact and fuse with a portion of the heat-fusible fibers included in the second fiber layer 28. Therefore, in the top sheet 16, the first fiber layer 26 and the second fiber layer 28 are firmly bonded, so that interlayer delamination between the first fiber layer 26 and the second fiber layer 28 can be suppressed.

[0098] The absorbent fibers of the second fiber layer 28 are held in the second fiber layer 28 by the mutually fused heat-bonded fibers of part of the first fiber layer 26 and part of the second fiber layer 28. Therefore, the fibers of the second fiber layer 28 can be prevented from falling out in the top sheet 16.

[0099] The body fluid supplied to the skin-opposite surface is transferred from the skin-opposite surface to the inside of the first fiber layer 26 by the heat-fusible fiber of the first fiber layer 26, so the body fluid is not easy to remain on the skin-opposite surface of the surface sheet 16. Therefore, the surface sheet 16 has excellent liquid permeability. The surface sheet 16 is a hot air nonwoven fabric. Therefore, the surface sheet 16 has excellent bulkiness and thus excellent liquid permeability.

[0100] Since the absorbent fibers are not exposed on the skin-opposite side, the body fluid transferred to the inside of the first fiber layer 26 is further transferred in the thickness direction T and reaches the interface between the first fiber layer 26 and the second fiber layer 28. The body fluid enters the second fiber layer 28 through a part of the heat-fusible fibers of the first fiber layer 26 and is smoothly transferred to the second fiber layer 28. The body fluid transferred to the second fiber layer 28 is absorbed by the absorbent fibers included in the second fiber layer 28. The body fluid absorbed by the absorbent fibers is absorbed by the absorbent body 18 disposed on the non-skin side. In this way, the surface sheet 16 has excellent liquid discharge properties because the body fluid supplied to the skin-opposite side is smoothly transferred from the first fiber layer 26 to the second fiber layer 28 and absorbed by the absorbent fibers of the second fiber layer 28.

[0101] As a result, in the top sheet 16 , interlayer delamination between the first fiber layer 26 and the second fiber layer 28 can be suppressed, and the liquid permeability and liquid discharge properties are excellent.

[0102] In this specification, liquid permeability is evaluated by the time it takes for body fluid to penetrate the surface sheet 16 from the skin-opposing surface, and liquid drainage is evaluated by the time it takes for body fluid to drain from the skin-opposing surface to the non-skin-opposing surface and disappear from the surface sheet 16.

[0103] If the first surface of the first fiber layer is used as the skin-facing surface and a concave portion depressed in the thickness direction is formed on the skin-facing surface, the distance from the skin-facing surface to the water-absorbent fibers included in the second fiber layer is short at the concave portion. That is, at the concave portion, the water-absorbent fibers that have absorbed body fluids are present at positions close to the skin-facing surface, so the body fluids supplied to the skin-facing surface are not transferred in the thickness direction but accumulated in the concave portion, thereby reducing the liquid permeability.

[0104] The top sheet 16 of this embodiment does not have a recessed portion formed on the skin-facing surface in the thickness direction T, so that body fluids can be prevented from accumulating in a specific location. Therefore, the top sheet 16 has excellent liquid permeability.

[0105] In the top sheet 16, the weight per unit area of ​​the second fiber layer 28 is uniform in the surface direction. Since the weight per unit area of ​​the second fiber layer 28 is uniform in the surface direction, the body fluid supplied to the skin-opposing surface and transferred in the thickness direction T is uniformly absorbed regardless of the position in the surface direction. Therefore, in the top sheet 16, excellent liquid discharge properties can be obtained regardless of the position in the surface direction.

[0106] Since the top sheet 16 contains 40 mass % to 70 mass % of absorbent fibers in the second fiber layer 28, the absorbent fibers can more reliably absorb body fluids discharged from the wearer. Therefore, the top sheet 16 has excellent liquid discharge properties when body fluids are repeatedly supplied.

[0107] When the third fiber layer 30 formed of heat-bonding fibers is provided on the non-skin side of the second fiber layer 28, the second fiber layer 28 is covered by the third fiber layer 30, and the water-absorbent fibers are prevented from being exposed from the non-skin opposite side. Therefore, in the top sheet 16, the water-absorbent fibers can be prevented from being separated.

[0108] Alternatively, another portion of the heat-fusible fibers of the first fiber layer 26 that enter the second fiber layer 28 may penetrate the second fiber layer 28, enter the third fiber layer 30, and fuse with a portion of the heat-fusible fibers of the third fiber layer 30. That is, a portion of the heat-fusible fibers of the first fiber layer 26 bends toward the second fiber layer 28 in the thickness direction T and enters the second fiber layer 28, and another portion of the heat-fusible fibers of the portion penetrates the second fiber layer 28, enters the third fiber layer 30, and fuses with a portion of the heat-fusible fibers of the third fiber layer 30. Therefore, in the surface sheet 16, in addition to the first fiber layer 26 and the second fiber layer 28 being firmly bonded, the second fiber layer 28 and the third fiber layer 30 are also firmly bonded, so that interlayer delamination can be suppressed.

[0109] The water-absorbent fibers of the second fiber layer 28 are held in the second fiber layer 28 by the mutually fused heat-bonded fibers of a portion of the first fiber layer 26 and a portion of the second fiber layer 28, and by the heat-bonded fibers of another portion of the first fiber layer 26 that penetrates the second fiber layer 28 and a portion of the heat-bonded fibers of the third fiber layer 30. Therefore, in the surface sheet 16, the fibers of the second fiber layer 28 can be further prevented from being detached.

[0110] Alternatively, a portion of the heat-fusible fibers of the second fiber layer 28 may enter the third fiber layer 30 and be fused to another portion of the heat-fusible fibers of the first fiber layer 26 and a portion of the heat-fusible fibers of the third fiber layer 30. That is, a portion of the heat-fusible fibers of the second fiber layer 28 may be bent toward the third fiber layer 30 in the thickness direction T, enter the third fiber layer 30, be fused to a portion of the heat-fusible fibers of the third fiber layer 30 in the third fiber layer 30, and further be fused to another portion of the heat-fusible fibers of the first fiber layer 26 that penetrate the second fiber layer 28 and enter the third fiber layer 30. Therefore, in the surface sheet 16, the second fiber layer 28 and the third fiber layer 30 are more firmly bonded, so that interlayer delamination can be further suppressed.

[0111] The water-absorbent fibers of the second fiber layer 28 are held in the second fiber layer 28 by the mutually fused heat-fusible fibers of a portion of the second fiber layer 28 and a portion of the heat-fusible fibers of the third fiber layer 30, and by another portion of the heat-fusible fibers of the first fiber layer 26 that penetrate the second fiber layer 28 and a portion of the heat-fusible fibers of the second fiber layer 28. Therefore, in the surface sheet 16, the fibers of the second fiber layer 28 can be further prevented from falling off.

[0112] (Variation Example)

[0113] The present invention is not limited to the above-described embodiments, and can be modified appropriately within the scope of the gist of the present invention. Figure 5 The surface piece 60 shown can also have concavoconvex. That is, the surface piece 60 has solid multiple convex parts 62 and multiple concave parts 64 that are concave from the first face 22 to the direction of the first face 22 from the second face 24 on the first face 22. In this specification, "solid" refers to a space with a fiber density that is significantly lower than the surroundings that does not have the movement of the liquid in the convex part 62. When the height difference of the highest part of the height of the highest part of the first face 22 and the lowest height of the deepest part of the first face 22 is set to d, the part that can be protruded to the upper side by the position of the height of d / 2 than the distance from the deepest part is called a convex part 62 and the part that is concave to the lower side by the position of the height of d / 2 than the distance from the deepest part is called a concave part 64. The surface piece 60 with concavoconvex can be formed by further passing through a gear processing step after the 4th operation in the above-mentioned manufacturing method. In the gear processing step, a pair of gear processing rollers sandwiches and partially presses a nonwoven fabric formed by joining the first fiber layer 26 , the second fiber layer 28 , and the third fiber layer, thereby forming a plurality of recessed portions 64 and obtaining the top sheet 60 .

[0114] Although not shown, the surface sheet 60 may also include a compression portion. The compression portion is intermittently arranged at the recess 64 along the length direction L. The compression portion may be arranged at equal intervals or at unequal intervals at the recess 64 in the length direction L. The recesses 64 adjacent in the width direction W may be at the same position or at different positions in the length direction L. The compression portion is formed by sandwiching the first fiber layer 26 from above and the third fiber layer 30 arranged across the second fiber layer 28 in the thickness direction T, and the first fiber layer 26, the second fiber layer 28 and the third fiber layer 30 are joined.

[0115] There are no particular limitations on the type and purpose of the absorbent article 10, and examples thereof include sanitary products and physiological products such as sanitary pads, disposable diapers (belt type, panty type), incontinence pads, and sweat-absorbing sheets, and these products may be for humans or animals other than humans such as pets. There are no particular limitations on the liquid to be absorbed by the absorbent article 10, and examples thereof include liquid excrement and body fluids of the wearer.

[0116] In the above embodiment, the first fiber layer is arranged on the skin side, but the present invention is not limited thereto. For example, the nonwoven fabric may be applied to the surface sheet by arranging the first fiber layer on the non-skin side and arranging the second fiber layer or the third fiber layer on the skin side. That is, the second side is the skin-opposite side. In this case, the nonwoven fabric has a high bulkiness and excellent liquid permeability because it has a first fiber layer formed of thermally fusible fibers and a second fiber layer containing absorbent fibers and thermally fusible fibers. The absorbent fibers of the second fiber layer are not exposed on the first side, so they are not easy to fall off from the first side.

[0117] (Measurement method)

[0118] <Weight per unit area, thickness, fiber density and fineness of the surface sheet>

[0119] The basis weight, thickness, fiber density and fineness of the surface sheet in the above-mentioned embodiment are measured by the following methods.

[0120] (1) Weight per unit area of ​​the surface sheet: A sample of a suitable size, such as 10 cm x 10 cm, is cut out from the surface sheet and placed in an atmosphere of 20°C and 65% humidity for 24 hours, and then the mass is measured. The measured mass is divided by the area of ​​the sample to calculate the weight per unit area of ​​the sample. The average value of the weight per unit area of ​​ten samples is taken as the weight per unit area of ​​the surface sheet.

[0121] (2) Thickness of the surface sheet: 15 cm 2 The thickness gauge of the probe (Model FS-60DS manufactured by Daiei Chemical Seiki Mfg. Co., Ltd.) is 3gf / cm 2 The thickness of the surface sheet was measured under a measurement load of 0.3 kPa. The thickness was measured at three locations on one sample, and the average value of the thickness at the three locations was taken as the thickness of the surface sheet.

[0122] (3) Fiber density of the top sheet: The fiber density of the top sheet is calculated by dividing the weight of the top sheet obtained by the above method by the thickness of the top sheet obtained by the above method.

[0123] (4) Fiber fineness: The fiber fineness is calculated by measuring the cross-sectional area of ​​the fiber by magnifying the cross-sectional shape of the fiber under a scanning electron microscope and calculating the cross-sectional area and the specific gravity of the fiber (i.e., the specific gravity of the constituent components of the fiber).

[0124] <Thickness of each part>

[0125] 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 fiber is dyed, and then the thickness of each part is measured. The dyeing of the hydrophilic fiber is carried out according to the following steps. (1) Prepare the surface sheet for measuring the thickness. (2) Add 1L of water to a pot and heat it to 60°C to 70°C. (3) Put the reagent KayastainQ (Japanese: カヤステインQ) (Sezen Co., Ltd.) into the pot of (2) and dissolve it. (4) Heat the pot to 80°C. (5) Put the surface sheet into the pot of (4) and leave it for 30 minutes. (5) Thereafter, rinse the surface sheet with running water. (6) Dry in an oven at 80°C for 1 hour. As a result of the above steps, the water-absorbent fiber (rayon) is dyed blue and the thermally fusible fiber (PET) is dyed yellow.

[0126] The thickness was measured according to the following steps. (1) The dyed surface sheet was cut into pieces with a length of 5 mm in the machine direction (MD) and 20 mm in the cross direction (CD) as a sample. (2) The sample was fixed to a jig using double-sided tape so that the CD cross section could be observed. (3) An enlarged photograph of the cross section was taken using a digital microscope VHX-7000 manufactured by Keyence Corporation, and the distance between two points of the plane was selected to measure the thickness of each part of the first fiber layer, the second fiber layer, and the third fiber layer of the surface sheet.

[0127] <Absorbent fiber content>

[0128] The content of the above-mentioned absorbent fiber in the second fiber layer can be obtained as follows. (1) After cutting a sample of the target area from a surface sheet that has been 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 absorbent fiber. (3) Wash the sample immersed in sulfuric acid with about 6 liters of water while sucking it onto a Buchner funnel, and then further wash it with about 1 liter of pure water. (4) After drying the washed sample at 105°C for 2 hours, measure the post-treatment mass (g) of the sample. (5) Calculate the mass (g) of the absorbent fiber in the sample by subtracting the post-treatment mass of the sample from the initial mass of the above-mentioned sample, and then obtain the content of the absorbent fiber by converting the obtained absorbent fiber content mass into a mass per unit area of ​​top view.

[0129] (Example)

[0130] A nonwoven fabric corresponding to the surface sheet corresponding to the above-mentioned embodiment was produced and evaluated. The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

[0131] (A) Sample

[0132] According to the above-mentioned manufacturing method, a nonwoven fabric of Example 1 having a first fiber layer, a second fiber layer, and a third fiber layer was prepared using a core-sheath fiber of PE / PET as a heat-fusible fiber and a fiber formed of rayon as a water-absorbent fiber. The flow rate of the first air and the flow rate of the second air in the third step were set to 5 m / s. 3 / min, and the suction roller pressure was set to 5.6 kPa. The temperature of the heated air in the fourth step was set to 136°C. The specific configuration is shown in Table 1.

[0133] As a comparative example, a nonwoven fabric of Comparative Example 2 was prepared in the same manner as in the above-described embodiment, except that the third and fourth steps in the above-described production method were not performed and the hydroentanglement method was used.

[0134] In addition, as a reference example, a nonwoven fabric of Reference Example 1 which is the same as that of the above embodiment was prepared except that the third step in the above manufacturing method was not performed. In addition, the flow rate of the first air and the flow rate of the second air in the third step in the above manufacturing method were set to 9 m / s by jetting. 3 The nonwoven fabric of Reference Example 2 was prepared by jetting air at a rate of 100 kPa / min and setting the suction drum pressure to 8.6 kPa. The nonwoven fabric of Reference Example 2 had a first fiber layer formed of core-sheath fibers of PE / PET and a second fiber layer of thermoplastic resin fibers including cotton as a water-absorbent fiber and core-sheath fibers of PE / PET, and had a concavo-convex structure on the first surface. A microscopic photograph of a cross section of the obtained nonwoven fabric is shown in FIG. Figure 6 to Figure 9 .

[0135] [Table 1]

[0136]

[0137] (B) Evaluation method

[0138] Various tests were performed according to the following procedures.

[0139] (Liquid permeability test and liquid drainage test)

[0140] (1) A sample cut into a size of 200 mm×100 mm and an acrylic plate having the same size as the sample and having a through hole of 40 mm×10 mm in the center were prepared.

[0141] (2) An acrylic plate was placed at the center of the surface of the sample on the first fiber layer side.

[0142] (3) Start the stopwatch while dropping 2 ml of horse blood using a micropipette.

[0143] (4) The time (permeation time) until the horse blood disappears from the sample and around the hole of the acrylic plate is measured.

[0144] (5) Continue to measure the time until the horse blood in the acrylic plate is drained away (drainage time).

[0145] (6) 30 seconds after the start of measurement, add 2 ml of horse blood for the second time (even if the first dose of horse blood has not been completely drained, the second measurement will be started).

[0146] (7) Carry out the measurements of (4) and (5) above in sequence.

[0147] (8) The acrylic plate was removed 60 seconds after the start of measurement, and 90 seconds after the start of measurement, 10 filter papers (35 mm×50 mm) and a weight (35 mm×50 mm, 525 g) whose weights were measured in advance were placed on the site where the horse blood had dripped.

[0148] (9) After 60 seconds, remove the weight and measure the weight of the filter paper.

[0149] (10) The rewetting amount (g) was determined by subtracting the mass of the filter paper before placement from the mass of the filter paper after placement on the sample, and the ratio (%) to the amount of horse blood absorbed (2 ml ≒ 2 g) was determined.

[0150] (Fiber shedding test)

[0151] (1) After the membrane filter was dried in an oven at 90° C. for 1 hour, it was naturally cooled in a desiccator for 30 minutes.

[0152] (2) Prepare five samples cut into a size of 100 mm x 100 mm.

[0153] (3) Prepare five 300 ml beakers filled with 300 ml of tap water.

[0154] (4) A rotor was placed in the beaker and stirred using a magnetic stirrer.

[0155] (5) Fold the sample into an inverted cone shape with the smoother surface as the outer side.

[0156] (6) Gently drop the sample in (5) into the center of the water surface in the beaker and start a stopwatch when the sample touches the center of the water surface.

[0157] (7) After stirring for 10 minutes, take out the sample.

[0158] The operations (4) to (7) were performed for each sample.

[0159] (8) Measure the weight of the membrane filter of (1).

[0160] (9) Place the membrane filter on the suction bottle, put the funnel on it and secure it with a holder.

[0161] (10) Add ethanol from the funnel to wet the membrane filter and turn on the vacuum pump to suction.

[0162] (11) Add the stirred water in the beaker through the funnel and aspirate.

[0163] (12) When the stirred water in the beaker has been sucked out, first unplug the hose connected to the suction bottle and then turn off the vacuum pump.

[0164] (13) Remove the funnel and take out the membrane filter containing the accumulated fibers into a culture dish.

[0165] (14) Cover the culture dish with plastic wrap to allow air to enter, and write the time on the plastic wrap.

[0166] (15) The membrane filter of (14) was dried in an oven at 90°C for 1 hour and naturally cooled in a desiccator for 30 minutes, after which the weight was measured.

[0167] The operations (9) to (15) were performed for each sample.

[0168] (16) The average value of the measured weight (n = 5) was taken as the fiber shedding amount (mg / m 2 ).

[0169] (C) Evaluation results

[0170] As shown in Table 1, the nonwoven fabric of Example 1 obtained excellent results in terms of liquid permeability and liquid discharge in both the first and second times. In addition, it was confirmed that the nonwoven fabric of Example 1 was excellent in rewetting properties.

[0171] The nonwoven fabric of Comparative Example 1 was produced by the hydroentanglement method, so it had low bulkiness and poor liquid permeability, and it was considered that the liquid drainage was poor because the water-absorbent fibers were present on the surface.

[0172] In Reference Example 1, the liquid discharge and rewetting properties were inferior to those in Example 1, and the amount of fiber shedding was large. In the nonwoven fabric of Reference Example 1, it is believed that since the third step in the manufacturing method of the above embodiment was not performed, the liquid was not smoothly transferred from the first fiber layer to the second fiber layer. In addition, in the nonwoven fabric of Reference Example 1, it is believed that since the water-absorbent fibers were difficult to be retained in the second fiber layer, the amount of fiber shedding increased.

[0173] The nonwoven fabric of Reference Example 2 was considered to have poor liquid permeability and liquid discharge because the concavo-convex structure was formed on the first surface by injecting air jets, and liquid easily accumulated in the concave portions.

[0174] Description of Reference Numerals

[0175] 10. Absorbent article; 12. Main body; 14. Wing part; 16. Surface sheet (non-woven fabric); 18. Absorber; 20. Back sheet; 22. First side (skin-opposing side); 24. Second side (non-skin-opposing side); 40. Laminated net; 42. Suction roller; 44. Inner cylinder; 46. Outer cylinder; 48. Suction area; 54. Dryer; 60. Surface sheet; 62. Protrusion; 64. Concave portion; CD, cross direction; MD, machine direction; L, length direction; T, thickness direction; W, width direction.

Claims

1. A nonwoven fabric for an absorbent article, comprising a first fiber layer and a second fiber layer in this order in a thickness direction, wherein: The first fiber layer has a first surface and is formed of heat-fusible fibers. The second fiber layer comprises water-absorbent fibers and thermally fusible fibers. A portion of the heat-fusible fibers in the first fiber layer enters the second fiber layer and is fused to a portion of the heat-fusible fibers in the second fiber layer. The water-absorbent fibers of the second fiber layer are not exposed on the first surface.

2. The nonwoven fabric according to claim 1, wherein The first fiber layer has no recessed portion formed on the first surface that is recessed in the thickness direction.

3. The nonwoven fabric according to claim 1 or 2, wherein: A third fiber layer made of thermally fusible fibers is provided on the second fiber layer on the side opposite to the first fiber layer.

4. The nonwoven fabric according to claim 3, wherein: Another part of the heat-fusible fibers of the first fiber layer that have entered the second fiber layer penetrates the second fiber layer, enters the third fiber layer, and is fused to the heat-fusible fibers of the third fiber layer.

5. The nonwoven fabric according to claim 4, wherein: A part of the heat-bonding fibers in the second fiber layer enters the third fiber layer and is fused to another part of the heat-bonding fibers in the first fiber layer and a part of the heat-bonding fibers in the third fiber layer.

6. The nonwoven fabric according to any one of claims 1 to 5, wherein The first surface of the first fiber layer is a skin-facing surface.

7. The nonwoven fabric according to claim 6, wherein: The second fiber layer has a uniform basis weight in the surface direction.

8. The nonwoven fabric according to claim 6 or 7, wherein: The second fiber layer contains 40% by mass or more and 70% by mass or less of the water-absorbent fiber.

9. A method for producing a nonwoven fabric for an absorbent article, wherein: The method for manufacturing the nonwoven fabric for the absorbent article comprises the following steps: A first step in which a gas is ejected from a first fiber web formed of thermally fusible fibers toward the first fiber web and a second fiber web including water-absorbent fibers and thermally fusible fibers that are sequentially overlapped in a thickness direction; as well as a second step in which the surfaces of the heat-fusible fibers of the first fiber web and the surfaces of the heat-fusible fibers of the second fiber web are melted to fuse the heat-fusible fibers to each other; In the first step, the gas is ejected under the condition that the amount of movement of the thermally fusible fibers in the first fiber web in the thickness direction is larger than the amount of movement in the width direction orthogonal to the machine direction.

Images