Nonwoven fabric for liquid-permeable sheet of absorbent article, absorbent article including said nonwoven fabric, and method for producing said nonwoven fabric

Abstract

The present disclosure addresses the problem of providing a nonwoven fabric which, when used as a liquid-permeable sheet of an absorbent article for absorbing menstrual blood, is less likely to be colored red due to menstrual blood and has an excellent property of hiding transferred menstrual blood inside the absorbent article.　Provided is a nonwoven fabric 1 which is for a liquid-permeable sheet of an absorbent article for absorbing menstrual blood and which comprises a heat-shrunken fiber layer 3 that includes heat-shrunken fibers 5 obtained by thermally shrinking heat-shrinkable hydrophobic fibers, said nonwoven fabric 1 being characterized in that: in the heat-shrunken fiber layer 3, the heat-shrunken fibers 5 extend in a first direction D1 and in a second direction D2; the heat-shrunken fiber layer 3 includes a plurality of hydrophilic regions 7 and a hydrophobic region 9; the plurality of hydrophilic regions 7 continuously or intermittently extend in a direction along the first direction D1 and are spaced apart from each other in the second direction D2; in each of the plurality of hydrophilic regions 7, hydrophilic fibers 13 penetrate the heat-shrunken fibers 5 from a first surface S1 to a second surface S2 in a thickness direction T; and in the heat-shrunken fiber layer 3, the heat-shrunken fibers 5 are disposed on the first surface S1.

Description

Nonwoven fabric for liquid-permeable sheet of absorbent article, absorbent article including said nonwoven fabric, and method for manufacturing said nonwoven fabric

[0001] The present disclosure relates to a nonwoven fabric for use as a liquid-permeable sheet in an absorbent article, an absorbent article including the nonwoven fabric as a liquid-permeable sheet, and a method for manufacturing the nonwoven fabric.

[0002] Nonwoven fabrics for use as liquid-permeable sheets in absorbent articles have been studied. For example, Patent Document 1 discloses an absorbent article including a topsheet, a backsheet, and an absorbent core disposed between the topsheet and the backsheet, wherein the topsheet has a first side and a second side, the first side facing the body, and the second side being in fluid communication with the absorbent core, and the topsheet further comprises: a. a first relatively hydrophobic component and a second relatively hydrophilic component; b. the relatively hydrophilic component extends through the relatively hydrophobic component and is disposed on both sides of the topsheet; and c. when tested by a jet acquisition and rewet test method, the absorbent article exhibits a rewet value of less than about 94 mg and a fluid acquisition rate of at least about 0.10 ml / s. Patent Document 1 aims to improve topsheets for disposable absorbent articles, which can provide a high jet acquisition rate and also provide improved dryness.

[0003] WO 2004 / 058118

[0004] Patent Document 1 does not disclose a nonwoven fabric for a liquid-permeable sheet of an absorbent article that absorbs menstrual blood, according to the present disclosure. Therefore, an object of the present disclosure is to provide a nonwoven fabric that, when used as a liquid-permeable sheet of an absorbent article that absorbs menstrual blood, is resistant to red discoloration by menstrual blood and has excellent concealment properties for menstrual blood that has migrated into the absorbent article.

[0005] The present inventors have discovered a nonwoven fabric for a liquid-permeable sheet of an absorbent article for absorbing menstrual blood, comprising a heat-shrunk fiber layer containing heat-shrunk fibers formed by heat-shrunk of hydrophobic heat-shrinkable fibers, and having a first direction, a second direction, and a thickness direction that are perpendicular to each other, wherein the heat-shrunk fiber layer has a first side and a second side, and in the heat-shrunk fiber layer, the heat-shrunk fibers extend in the first direction and the second direction, the heat-shrunk fiber layer comprises a plurality of hydrophilic regions and hydrophobic regions, the plurality of hydrophilic regions extend continuously or intermittently in the first direction and are spaced apart in the second direction, and in each of the plurality of hydrophilic regions, the hydrophilic fibers penetrate the heat-shrunk fibers in the thickness direction from the first side to the second side, and the heat-shrunk fibers are arranged on the first side of the heat-shrunk fiber layer.

[0006] When used as a liquid-permeable sheet in an absorbent article for absorbing menstrual blood, the nonwoven fabric according to the present disclosure is resistant to red discoloration by menstrual blood and has excellent concealing properties for menstrual blood that has migrated into the absorbent article.

[0007] FIG. 1 is a diagram illustrating a nonwoven fabric 1 according to the first embodiment. FIG. 2 is a diagram illustrating a manufacturing apparatus 101 for manufacturing a nonwoven fabric 1 according to the first embodiment. FIG. 3 is a diagram illustrating an example. FIG. 4 is a diagram illustrating an example. FIG. 5 is a diagram illustrating an example. FIG. 6 is a diagram illustrating an example. FIG. 7 is a diagram illustrating an example. FIG. 8 is a diagram illustrating an example. FIG. 9 is a diagram illustrating an example. FIG. 10 is a diagram illustrating an example. FIG. 11 is a diagram illustrating an example.

[0008] Specifically, the present disclosure relates to the following aspects: [Aspect 1A] A nonwoven fabric for a liquid-permeable sheet of an absorbent article for absorbing menstrual blood, comprising a heat-shrunk fiber layer containing heat-shrunk fibers formed by heat-shrunk of hydrophobic heat-shrinkable fibers, and having a first direction, a second direction, and a thickness direction that are perpendicular to each other, wherein the heat-shrunk fiber layer has a first side and a second side, the heat-shrunk fibers extend in the first direction and the second direction in the heat-shrunk fiber layer, the heat-shrunk fiber layer comprises a plurality of hydrophilic regions and hydrophobic regions, the hydrophilic regions extend continuously or intermittently in the first direction and are spaced apart in the second direction, and in each of the hydrophilic regions, the hydrophilic fibers penetrate the heat-shrunk fiber in the thickness direction from the first side to the second side, and the heat-shrunk fibers are arranged on the first side of the heat-shrunk fiber layer.

[0009] The nonwoven fabric has predetermined hydrophobic and hydrophilic regions. Therefore, when the nonwoven fabric is used as a liquid-permeable sheet in an absorbent article that absorbs menstrual blood, with the first surface of the nonwoven fabric forming the skin-contacting surface of the liquid-permeable sheet (hereinafter, sometimes simply referred to as "when the nonwoven fabric is used in an absorbent article"), menstrual blood that reaches the first surface of the nonwoven fabric is unlikely to remain in the hydrophobic regions containing hydrophobic crimped fibers or to penetrate into the hydrophobic regions, and is likely to migrate into the absorbent article through the hydrophilic regions that penetrate through the thickness from the first surface to the second surface. Therefore, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric is unlikely to be stained red by menstrual blood.

[0010] After menstrual blood has migrated into the absorbent article, at least the first surface of the hydrophobic region of the nonwoven fabric contains crimped fibers, making it difficult for visible light to pass through, and thus making it difficult for the menstrual blood that has migrated into the absorbent article to be visually recognized. Furthermore, because the hydrophobic region of the nonwoven fabric contains hydrophobic crimped fibers, it is difficult for the menstrual blood that has migrated into the absorbent article to physically pass through (rewetback is unlikely to occur).

[0011] Furthermore, since the post-heat-shrinkage fibers extend in the first and second directions in the hydrophilic regions as well, when the nonwoven fabric is used in an absorbent article, the hydrophilic regions are less likely to open even when a force such as body pressure is applied, making it difficult to see menstrual blood held by the hydrophilic fibers and absorbed inside the absorbent article from the outside of the absorbent article. As a result, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric is less likely to be stained red by menstrual blood and has excellent ability to conceal menstrual blood that has migrated inside the absorbent article.

[0012] [Aspect 1B] A nonwoven fabric for a liquid-permeable sheet of an absorbent article for absorbing liquid, comprising a heat-shrunk fiber layer containing heat-shrunk fibers formed by heat-shrunk of hydrophobic heat-shrinkable fibers, and having a first direction, a second direction, and a thickness direction that are perpendicular to one another, wherein the heat-shrunk fiber layer has a first side and a second side, the heat-shrunk fibers extend in the first direction and the second direction in the heat-shrunk fiber layer, the heat-shrunk fiber layer comprises a plurality of hydrophilic regions and hydrophobic regions, the hydrophilic regions extend continuously or intermittently in the first direction and are spaced apart in the second direction, and in each of the hydrophilic regions, the hydrophilic fibers penetrate the heat-shrunk fibers in the thickness direction from the first side to the second side, and the heat-shrunk fibers are arranged on the first side in the heat-shrunk fiber layer.

[0013] For the same reasons as in Aspect 1A, when the nonwoven fabric is used in an absorbent article that absorbs liquid, the nonwoven fabric is resistant to discoloration by the liquid and has excellent concealing properties for the liquid that has migrated into the absorbent article. Note that the "absorbent article that absorbs liquid" is referred to as a "liquid-absorbing absorbent article."

[0014] Examples of the liquid include body fluids such as menstrual blood, blood (e.g., plasma, blood cells), vaginal discharge, breast milk, urine, nasal discharge, and saliva. The liquid-absorbing absorbent article is not particularly limited as long as it has an absorbent core. Examples of the liquid-absorbing absorbent article include absorbent articles for women, such as sanitary napkins, sanitary shorts, tampons, bedsore pads, adhesive bandages, food packaging sheets, panty liners, breast pads, disposable diapers, incontinence pads, urine absorption sheets, disposable pants, and masks.

[0015] The disclosures in this specification can be applied not only to absorbent articles that absorb menstrual blood but also to the above-mentioned liquid-absorbing absorbent articles. In such cases, the terms "absorbent article" and "menstrual blood" can be read as "liquid-absorbing absorbent article" and "liquid," respectively, and the terms "red" and "reddish" can be read as "the color of the liquid" and "the color of the liquid," respectively.

[0016] [Aspect 2] The nonwoven fabric according to Aspect 1A or 1B, wherein in at least some of the hydrophilic regions, a one-side hydrophobic region, which is the hydrophobic region located on one side of the hydrophilic regions in the second direction, and a second-side hydrophobic region, which is the hydrophobic region located on the other side of the hydrophilic regions in the second direction, are connected by the heat-shrunk fibers that are continuously arranged between the one-side hydrophobic region and the second-side hydrophobic region.

[0017] In the nonwoven fabric, at least some of the hydrophilic regions are connected by heat-shrunk fibers that are continuously arranged from one hydrophobic region to the other hydrophobic region, so when the nonwoven fabric is used in an absorbent article, the hydrophilic regions are less likely to open even when a force such as body pressure is applied, making it difficult to see menstrual blood held by the hydrophilic fibers and absorbed into the absorbent article from the outside of the absorbent article. As a result, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent ability to conceal menstrual blood that has migrated into the absorbent article.

[0018] [Aspect 3] The nonwoven fabric according to Aspect 1A, 1B, or 2, wherein the heat-shrunk fibers are arranged from the first surface to the second surface in the thickness direction in the hydrophobic region.

[0019] In the hydrophobic region of the nonwoven fabric, the heat-shrunk fibers are arranged in the thickness direction from the first surface to the second surface. Therefore, when the nonwoven fabric is used in an absorbent article, the hydrophobic region makes it difficult for visible light to pass through, making it difficult to visually recognize menstrual blood that has migrated into the absorbent article. Furthermore, because the hydrophobic region of the nonwoven fabric contains hydrophobic crimped fibers, it is difficult for menstrual blood that has migrated into the absorbent article to physically pass through (rewetback is unlikely to occur).

[0020] [Aspect 4] The nonwoven fabric according to Aspect 1A, 1B, 2, or 3, further comprising a hydrophilic fiber layer containing hydrophilic fibers and bonded to the second surface of the heat-shrunk fiber layer.

[0021] The nonwoven fabric further includes a predetermined hydrophilic fiber layer containing hydrophilic fibers. Therefore, when the nonwoven fabric is used in an absorbent article, the hydrophilic fiber layer can diffuse menstrual blood that has permeated the nonwoven fabric (liquid-permeable sheet) in the planar direction and easily transfer it to a member adjacent to the menstrual blood retention member (e.g., absorbent body) that retains the menstrual blood. As a result, menstrual blood is easily transferred to a member adjacent to the menstrual blood retention member while diffusing it from the excretory opening contact region in the first and second directions, and ultimately the redness of the menstrual blood retention member is less likely to become darker in parts. Therefore, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties.

[0022] Aspect 5: The nonwoven fabric according to Aspect 4, wherein the hydrophilic fiber layer has a plurality of protrusions protruding from the second surface of the heat-shrunk fiber layer in the thickness direction and extending in the first direction, and at least some of the protrusions are arranged so as to overlap the hydrophobic regions in a plan view of the nonwoven fabric in the thickness direction.

[0023] In the nonwoven fabric, the hydrophilic fiber layer has a predetermined number of protrusions. Therefore, when the nonwoven fabric is used in an absorbent article, menstrual blood that passes through the hydrophilic region and penetrates the nonwoven fabric in the thickness direction is easily transferred via the protrusions to a component adjacent to the menstrual blood retention component side. Furthermore, the protrusions that are arranged to overlap with the hydrophobic region easily transfer menstrual blood to a region of the component adjacent to the menstrual blood retention component that overlaps with the hydrophobic region in the thickness direction. As a result, the redness of the menstrual blood retention component is less likely to become darker in parts. Therefore, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties.

[0024] [Aspect 6] The nonwoven fabric according to Aspect 5, wherein at least some of the plurality of protrusions are arranged so as to further overlap some of the plurality of hydrophilic regions when viewed in a plan view in the thickness direction of the nonwoven fabric.

[0025] In the nonwoven fabric, at least some of the protrusions are arranged so as to overlap portions of the hydrophilic regions when viewed from above in the thickness direction of the nonwoven fabric. Therefore, when the nonwoven fabric is used in an absorbent article, menstrual blood that has passed through the nonwoven fabric through the hydrophilic regions is more likely to migrate via the protrusions to regions of the member adjacent to the menstrual blood retention member that overlap with the hydrophobic regions in the thickness direction. As a result, the redness of the menstrual blood retention member is less likely to become darker in parts. Therefore, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties.

[0026] [Aspect 7] The nonwoven fabric according to any one of Aspects 1A, 1B, and 2 to 6, wherein the plurality of hydrophilic regions are arranged at a pitch in the second direction of 0.3 to 2.0 mm.

[0027] The nonwoven fabric has a plurality of hydrophilic regions arranged at a predetermined pitch. Therefore, when the nonwoven fabric is used in an absorbent article, menstrual blood is easily transferred through the hydrophilic regions to a member adjacent to the menstrual blood retention member, and menstrual blood is less likely to remain on the first surface of the hydrophobic region. As a result, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties.

[0028] [Aspect 8] The nonwoven fabric according to any one of Aspects 1A, 1B, and 2 to 7, wherein the nonwoven fabric is a spunlace nonwoven fabric. Because the nonwoven fabric is a spunlace nonwoven fabric, it is easier to ensure the thickness of the nonwoven fabric compared to nonwoven fabrics with compressed portions. As a result, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties. Furthermore, the nonwoven fabric has excellent texture.

[0029] [Aspect 9] The nonwoven fabric according to any one of Aspects 1A, 1B, and 2 to 8, wherein the nonwoven fabric does not have a heat-fused portion where the fibers are heat-fused after the heat shrinkage.

[0030] Since the nonwoven fabric does not have a predetermined heat-sealed portion, it is easier to ensure the thickness of the nonwoven fabric compared to a nonwoven fabric that has a heat-sealed portion. As a result, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties. In addition, the nonwoven fabric has excellent texture.

[0031] [Aspect 10] The nonwoven fabric according to any one of Aspects 1A, 1B, and 2 to 9, wherein the hydrophilic fibers are cellulosic fibers.

[0032] In the nonwoven fabric, since the hydrophilic fibers are cellulosic fibers, when the nonwoven fabric is used in an absorbent article, menstrual blood is easily drawn into the absorbent article through the multiple hydrophilic regions, which makes it difficult for menstrual blood to remain on the first surface of the hydrophobic regions, and ultimately, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties.

[0033] [Aspect 11] The nonwoven fabric according to any one of Aspects 1A, 1B, and 2 to 10, wherein the nonwoven fabric has a thickness of 0.3 to 2.5 mm. Because the nonwoven fabric has a predetermined thickness, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties.

[0034] [Aspect 12] An absorbent article comprising, as a liquid-permeable sheet, the nonwoven fabric according to any one of Aspects 1A, 1B, and 2 to 11. The absorbent article is resistant to red discoloration by menstrual blood and has excellent concealing properties for menstrual blood that has migrated into the absorbent article.

[0035] Aspect 13 is a method for producing the nonwoven fabric according to any one of Aspects 1A, 1B, and 2 to 11, comprising: a preparation step of preparing a laminated web in which a hydrophilic fiber sheet containing the hydrophilic fibers is laminated on a heat-shrinkable fiber web containing the heat-shrinkable fibers; a water-jet processing step of water-jetting the laminated web from the hydrophilic fiber sheet side; and a nonwoven fabric forming step of heating the water-jet-treated laminated web to heat-shrink the heat-shrinkable fibers and form the heat-shrunk fibers, thereby forming the nonwoven fabric.

[0036] The above-described manufacturing method allows the nonwoven fabric according to the first aspect to be easily manufactured.

[0037] [Aspect 14] The method according to Aspect 13, wherein the hydrophilic fibrous sheet has a wet strength of 2.0 N / 25 mm or less in any direction. In this production method, the hydrophilic fibrous sheet has the predetermined wet strength, and therefore the nonwoven fabric according to Aspect 1 can be easily produced.

[0038] [Aspect 15] The method according to aspect 13 or 14, wherein the hydrophilic fibrous sheet is a web, nonwoven fabric, or tissue paper containing the hydrophilic fibers.

[0039] In the above-described manufacturing method, the hydrophilic fiber sheet is made of a predetermined material, and therefore the nonwoven fabric according to the first aspect can be easily manufactured.

[0040] Aspect 16: The method according to any one of Aspects 13 to 15, wherein in the water jet treatment step, while transporting the laminate web in the transport direction, a water jet device having a plurality of nozzles with an inner diameter of 0.03 to 0.17 mm arranged at a pitch of 0.3 to 2.0 mm in a direction perpendicular to the transport direction is disposed so that the distance between the plurality of nozzles and the laminate web is 10 to 60 mm, and water is sprayed from the plurality of nozzles onto the laminate web at a water pressure of 1 to 15 MPa, thereby water jet treating the laminate web.

[0041] In the above-described manufacturing method, the laminated web is subjected to water jet processing under predetermined conditions, and therefore the nonwoven fabric according to Aspect 1 can be easily manufactured.

[0042] [Aspect 17] The method according to any one of Aspects 13 to 16, wherein in the nonwoven fabric forming step, the heat-shrinkable fiber is heat-shrunk to form the nonwoven fabric having a thickness greater than that of the water-jet treated laminate web.

[0043] In the above-mentioned production method, a nonwoven fabric having a predetermined thickness is formed by heat-shrinking the heat-shrinkable fiber, and the formed nonwoven fabric has excellent hiding power and is soft to the touch.

[0044] The nonwoven fabric for a liquid-permeable sheet of an absorbent article that absorbs menstrual blood, the absorbent article that includes the nonwoven fabric as a liquid-permeable sheet, and a method for manufacturing the nonwoven fabric according to the present disclosure will be described in detail below. The absorbent article will also be described in the section on the nonwoven fabric.

[0045] The nonwoven fabric according to the present disclosure is a nonwoven fabric for a liquid-permeable sheet of an absorbent article that absorbs menstrual blood. In this specification, the "nonwoven fabric for a liquid-permeable sheet of an absorbent article that absorbs menstrual blood" may be simply referred to as the "nonwoven fabric."

[0046] [Nonwoven Fabric] Fig. 1 is a diagram illustrating a nonwoven fabric 1 according to one embodiment of the present disclosure (hereinafter referred to as "first embodiment"). Specifically, Fig. 1 is a perspective view of the nonwoven fabric 1 according to the first embodiment. The nonwoven fabric 1 is a nonwoven fabric for a liquid-permeable sheet of an absorbent article that absorbs menstrual blood. The nonwoven fabric 1 has a first direction D1, a second direction D2, and a thickness direction T that are perpendicular to each other. The nonwoven fabric 1 includes a heat-shrunk fiber layer 3 containing heat-shrunk fibers 5 formed by heat-shrunk hydrophobic heat-shrinkable fibers. Specifically, the heat-shrinkable fibers are latently crimpable fibers, and the heat-shrunk fibers 5 are crimped latently crimpable fibers.

[0047] The heat-shrunk fiber layer 3 has a first surface S1 that forms a skin contact surface when used in a liquid-permeable sheet, and a second surface S2 opposite to the first surface S1. In the heat-shrunk fiber layer 3, the heat-shrunk fibers 5 extend in a first direction D1 and a second direction D2 while crimping.

[0048] The heat-shrunk fiber layer 3 is partitioned into a plurality of hydrophilic regions 7 and a plurality of hydrophobic regions 9. The hydrophilic regions 7 extend continuously parallel to the first direction D1 and are spaced apart at a predetermined pitch P in the second direction D2. In each of the hydrophilic regions 7, the hydrophilic fibers 13 penetrate the heat-shrunk fiber 5 in the thickness direction T from the first surface S1 to the second surface S2. The hydrophilic fibers 13 are cellulosic fibers, specifically rayon fibers. In each of the heat-shrunk fiber layers 3, the heat-shrunk fiber 5 is arranged in the thickness direction T from the first surface S1 to the second surface S2.

[0049] In Fig. 1, the hydrophilic fibers 13 are shown thicker than the heat-shrunk fibers 5 to facilitate understanding of the invention, but this does not mean the relationship between the actual fiber diameters of the hydrophilic fibers 13 and the heat-shrunk fibers 5. The same applies to the fiber lengths of the hydrophilic fibers 13 and the heat-shrunk fibers 5. In Fig. 1, the heat-shrunk fibers 5 are shown spirally, but this does not represent the actual crimp state, orientation, etc. of the heat-shrunk fibers.

[0050] Since the nonwoven fabric 1 has a plurality of hydrophilic regions 7 and a plurality of hydrophobic regions 9, when the nonwoven fabric 1 is used in an absorbent article, the nonwoven fabric 1 is less likely to be stained red by menstrual blood and has excellent concealing properties for menstrual blood that has migrated into the absorbent article.

[0051] In each of the plurality of hydrophilic regions 7, a one-side hydrophobic region 9a, which is the hydrophobic region 9 present on one side of the hydrophilic region 7 in the second direction D2, and an other-side hydrophobic region 9b, which is the hydrophobic region 9 present on the other side of the second direction D2, are connected by the continuous heat-shrunk fibers 5. In other words, each of the plurality of hydrophilic regions 7 extends parallel to the first direction D1 and does not have a fracture surface that penetrates in the thickness direction T and breaks the heat-shrunk fibers 5. As a result, when the nonwoven fabric 1 is used in an absorbent article, even when a force such as body pressure is applied, the plurality of hydrophilic regions 7 are unlikely to open, and menstrual blood held by the hydrophilic fibers and menstrual blood absorbed inside the absorbent article is unlikely to be visible from the outside of the absorbent article.

[0052] The nonwoven fabric 1 further includes a hydrophilic fiber layer 11 containing hydrophilic fibers 13 and bonded to the second surface S2 of the heat-shrunk fiber layer 3. Specifically, the hydrophilic fiber layer 11 is composed of hydrophilic fibers 13 and includes a plurality of protrusions 15 that protrude in the thickness direction T from the second surface S2 of the heat-shrunk fiber layer 3 in the direction opposite to the heat-shrunk fiber layer 3 and extend parallel to the first direction D1. In a plan view of the nonwoven fabric 1 in the thickness direction T, each of the plurality of protrusions 15 is arranged so as to overlap a hydrophobic region 9 and two hydrophilic regions 7 adjacent to the hydrophobic region 9 in the second direction D2. This makes it easier for menstrual blood that has permeated the nonwoven fabric 1 in the thickness direction T through the hydrophilic regions 7 to migrate via the protrusions 15 to regions of a member adjacent to the menstrual blood retention member that overlap with the hydrophobic regions 9 in the thickness direction T.

[0053] The nonwoven fabric according to the present disclosure is a nonwoven fabric for use as a liquid-permeable sheet in an absorbent article that absorbs menstrual blood. The absorbent article is not particularly limited as long as it is equipped with a menstrual blood retention member that absorbs menstrual blood, and examples include absorbent articles for women, such as sanitary napkins and sanitary shorts. Examples of the menstrual blood retention member include an absorbent body equipped with an absorbent core, an absorbent core, and a core wrap that covers the absorbent core. Examples of the liquid-permeable sheet include a liquid-permeable top sheet with a skin-contacting surface, a core wrap that covers the absorbent core, and a liquid-diffusion sheet (second sheet) that is disposed between the top sheet and the absorbent core. Examples of components adjacent to the menstrual blood retention member side of the liquid-permeable sheet include the menstrual blood retention member, the second sheet, and the core wrap.

[0054] The nonwoven fabric according to the present disclosure has a first direction, a second direction, and a thickness direction that are perpendicular to each other. Examples of the first direction and the second direction include the conveying direction during manufacturing and the orthogonal direction perpendicular to the conveying direction, respectively. In this specification, the direction including the first direction and the second direction may be referred to as the planar direction.

[0055] The nonwoven fabric according to the present disclosure includes a heat-shrunk fiber layer containing heat-shrunk fibers formed by heat-shrunk hydrophobic heat-shrinkable fibers. The heat-shrunk fiber layer has a first surface and a second surface extending in the planar direction. Examples of the heat-shrinkable fibers include fibers whose actual fiber length is shortened by heat treatment and fibers whose apparent fiber length is shortened by heat treatment (e.g., latently crimpable fibers whose apparent fiber length is shortened by crimping). Examples of the latently crimpable fibers include composite fibers containing two thermoplastic resins with different shrinkage rates, such as eccentric core-sheath composite fibers and side-by-side composite fibers.

[0056] Examples of the composite fibers include eccentric sheath-core composite fibers having a core made of polyethylene terephthalate resin and a sheath made of polyethylene resin; eccentric sheath-core composite fibers having a core made of polypropylene resin and a sheath made of polyethylene resin; eccentric sheath-core composite fibers having a core made of high-melting-point polypropylene resin and a sheath made of low-melting-point polypropylene resin; side-by-side composite fibers made of polyethylene terephthalate resin (PET) and low-melting-point polyethylene terephthalate resin; side-by-side composite fibers made of polyethylene terephthalate resin and polyethylene resin; and side-by-side composite fibers made of polypropylene resin and polyethylene resin.

[0057] The heat-shrinkable fibers preferably have an average fiber length of 20 mm or more, more preferably 30 mm or more. The heat-shrinkable fibers preferably have an average fiber length of 70 mm or less, more preferably 60 mm or less. This provides excellent formability for the nonwoven fabric according to the present disclosure.

[0058] The heat-shrinkable fiber preferably has a fineness of 0.5 dtex or more, more preferably 1.0 dtex or more. The heat-shrinkable fiber preferably has a fineness of 8.0 dtex or less, more preferably 7.0 dtex or less. This makes it easier to ensure a consistent thickness of the nonwoven fabric according to the present disclosure, resulting in an excellent feel on the skin and reduced rewetback. Furthermore, since a consistent number of heat-shrinkable fibers can be ensured, the nonwoven fabric has excellent hiding power.

[0059] In the heat-shrunk fiber layer of the nonwoven fabric according to the present disclosure, the heat-shrunk fibers extend in a first direction and a second direction. The heat-shrunk fiber layer includes a plurality of hydrophilic regions and a single or multiple hydrophobic regions. The heat-shrunk fiber layer may be partitioned into a plurality of hydrophilic regions and a single or multiple hydrophobic regions.

[0060] The hydrophilic regions extend continuously or intermittently in a planar direction parallel to the first direction and are spaced apart in a second direction. In the thickness direction, in each of the hydrophilic regions, a hydrophilic fiber penetrates the heat-shrunk fiber in the thickness direction from the first surface to the second surface. In the present disclosure, the "direction parallel to the first direction" means a direction that crosses the first direction at an angle of preferably less than 45°, more preferably 30° or less, even more preferably 20° or less, and even more preferably 5° or less.

[0061] The nonwoven fabric in which the heat-shrunk fiber layer comprises a plurality of hydrophilic regions and a single hydrophobic region may be one in which each of the plurality of hydrophilic regions extends intermittently in the first direction, in other words, a nonwoven fabric in which a single hydrophobic region includes a plurality of hydrophilic regions that extend intermittently in the first direction and are spaced apart in the first and second directions.

[0062] The nonwoven fabric in which the heat-shrunk fiber layer comprises a plurality of hydrophilic regions and a plurality of hydrophobic regions may have a plurality of hydrophilic regions each extending continuously in a first direction, a plurality of hydrophobic regions each extending continuously in the first direction, and the hydrophilic regions and the hydrophobic regions alternately arranged in a second direction.

[0063] The plurality of hydrophilic regions can be spaced apart in the second direction at a predetermined pitch. The predetermined pitch is preferably 0.3 mm or more, more preferably 0.5 mm or more, and even more preferably 0.7 mm or more. The predetermined pitch is preferably 2.0 mm or less, more preferably 1.7 mm or less, and even more preferably 1.5 mm or less. This makes it easier for menstrual blood to pass through the plurality of hydrophilic regions and migrate to a member adjacent to the menstrual blood retention member when the nonwoven fabric is used in an absorbent article, and makes it less likely for menstrual blood to remain on the first surface of the hydrophobic region.

[0064] The hydrophilic fibers may be those used in the art as hydrophilic fibers, such as absorbent fibers, cellulosic fibers, and non-absorbent fibers, such as synthetic fibers that have been hydrophilized. Examples of the cellulosic fibers include natural cellulose fibers, regenerated cellulose fibers, refined cellulose fibers, and semi-synthetic cellulose fibers. Examples of the natural cellulose fibers include plant fibers, such as pulp fibers, seed hair fibers (e.g., cotton fibers), bast fibers (e.g., hemp), vein fibers (e.g., Manila hemp), and fruit fibers (e.g., palm).

[0065] The pulp fibers include those known in the art, such as wood pulp fibers and non-wood pulp fibers. Examples of the wood pulp fibers include softwood pulp fibers and hardwood pulp fibers. Examples of the non-wood pulp fibers include straw pulp fibers, bagasse pulp fibers, reed pulp fibers, kenaf pulp fibers, mulberry pulp fibers, bamboo pulp fibers, hemp pulp fibers, and cotton pulp fibers (e.g., cotton linter fibers). The pulp fibers may be waste paper, recycled pulp fibers, etc.

[0066] The cotton fiber includes Hirsutum cotton fiber (e.g., upland cotton), Barbadense cotton fiber, Arboreum cotton fiber, and Helbaceum cotton fiber. The cotton fiber may also be organic cotton fiber or Pre-Organic Cotton (trademark) fiber. Organic cotton fiber refers to cotton certified by GOTS (Global Organic Textile Standard).

[0067] Examples of the regenerated cellulose fibers include rayon, for example, viscose rayon obtained from viscose, polynosic and modal, and cuprammonium rayon (also called "cupra") obtained from a cuprammonium salt solution of cellulose.

[0068] The purified cellulose fiber includes lyocell, specifically, a fiber obtained by dissolving pulp in an aqueous solution of N-methylmorpholine N-oxide to form a spinning dope (dope) and extruding the dope into a dilute solution of N-methylmorpholine N-oxide. The purified cellulose is commercially available, for example, under the trade name Tencel (trademark). The semi-synthetic fiber includes semi-synthetic cellulose, such as acetate fibers, e.g., triacetate and diacetate fibers.

[0069] The hydrophilically treated synthetic fibers include those commonly used in the art, such as those containing a single component, e.g., a single fiber, or those containing multiple components, e.g., a composite fiber. The synthetic fibers may also be biomass plastics, recycled materials, etc.

[0070] Examples of the above components include polyolefin-based polymers such as polyethylene and polypropylene; polyester-based polymers such as terephthalate-based polymers such as polyethylene terephthalate, polybutylene terephthalate, and polypentylene terephthalate; polyamide-based polymers such as nylon 6 and nylon 6,6; acrylic-based polymers; polyacrylonitrile-based polymers; and modified products thereof.

[0071] The synthetic fibers are preferably biodegradable, which makes the nonwoven fabric more biodegradable. Examples of components of the biodegradable synthetic fibers include polybutylene succinate, poly(hydroxybutyrate / hydroxyhexanoate), polycaprolactone, poly(caprolactone / butylene succinate), poly(butylene succinate / adipate), poly(butylene succinate / carbonate), poly(butylene adipate / terephthalate), polyethylene succinate, polylactic acid, polyhydroxybutyrate, polyglycolic acid, and cellulose acetate.

[0072] The hydrophilic fibers are preferably cellulosic fibers. When the nonwoven fabric is used in an absorbent article, menstrual blood is easily drawn into the absorbent article through the hydrophilic regions. As a result, menstrual blood is less likely to remain on the first surface of the hydrophobic region.

[0073] The hydrophilic fibers, excluding pulp fibers, preferably have an average fiber length of 20 mm or more, and more preferably 30 mm or more. The hydrophilic fibers also preferably have an average fiber length of 70 mm or less, and more preferably 60 mm or less. This provides excellent formability for the nonwoven fabric according to the present disclosure, and facilitates the migration of menstrual blood through the hydrophilic regions into the absorbent article. When the hydrophilic fibers are pulp fibers, for the same reasons, the hydrophilic fibers preferably have an average fiber length of 0.1 mm or more, and more preferably 1 mm or more, and the hydrophilic fibers preferably have an average fiber length of 5 mm or less, and more preferably 4 mm or less.

[0074] The hydrophilic fibers, excluding natural cellulose fibers, preferably have a fineness of 0.5 dtex or more, and more preferably 1.0 dtex or more. The hydrophilic fibers, excluding natural cellulose fibers, preferably have a fineness of 5.0 dtex or less, and more preferably 4.0 dtex or less. This allows menstrual blood to easily migrate through the hydrophilic regions into the absorbent article.

[0075] In this specification, the average fiber length of fibers including heat-shrinkable fibers and hydrophilic fibers (excluding pulp fibers) is measured in accordance with "A7.1.1 Method A (standard method) - measuring the length of individual fibers on a graduated glass plate" in "A7.1 Measurement of fiber length" of Annex A of JIS L 1015:2010. Note that this method is a test method equivalent to ISO 6989 published in 1981.

[0076] As used herein, the average fiber length of pulp fibers refers to the weight-weighted average fiber length, and refers to the L(w) value measured by Kajaani FiberLab fiber properties (off-line) manufactured by Metso Automation.

[0077] The heat-shrunk fiber layer preferably has the heat-shrunk fibers on at least a first surface, and the heat-shrunk fibers are preferably arranged from the first surface to the second surface in the thickness direction. When the nonwoven fabric is used in an absorbent article, the hydrophobic region makes it difficult for visible light to pass through, making it difficult to visually recognize menstrual blood that has migrated into the absorbent article. Furthermore, since the hydrophobic region of the nonwoven fabric contains hydrophobic crimped fibers, it becomes difficult for menstrual blood that has migrated into the absorbent article to physically pass through (rewetback is less likely to occur).

[0078] In the nonwoven fabric according to the present disclosure, preferably in at least some of the hydrophilic regions, and more preferably in all of the hydrophilic regions, a one-side hydrophobic region, which is a hydrophobic region located on one side of the hydrophilic regions in the second direction, and an other-side hydrophobic region, which is a hydrophobic region located on the other side of the hydrophilic regions in the second direction, are connected by heat-shrunk fibers continuously arranged between the one-side hydrophobic region and the other-side hydrophobic region. As a result, when the nonwoven fabric is used in an absorbent article, even when a force such as body pressure is applied, the hydrophilic region is less likely to open, and menstrual blood held by the hydrophilic fibers and menstrual blood absorbed into the absorbent article is less likely to be visible from the outside of the absorbent article.

[0079] The nonwoven fabric according to the present disclosure may be composed of only a single layer of heat-shrunk fiber layer in the thickness direction, or may be composed of two or more layers including a heat-shrunk fiber layer and an additional layer. When the nonwoven fabric according to the present disclosure is composed of two or more layers, the additional layer may be bonded to the second surface of the heat-shrunk fiber layer, i.e., the additional layer may not be bonded to the first surface of the heat-shrunk fiber layer. This allows the first surface of the heat-shrunk fiber layer to be used as the skin-contacting surface of the above-mentioned top sheet, for example, and the nonwoven fabric is less likely to be discolored red by menstrual blood and has excellent concealment properties for menstrual blood that has migrated into the absorbent article.

[0080] The bonding of the post-heat-shrunk fiber layer and the additional layer is not particularly limited, and examples thereof include bonding by entanglement of the fibers constituting the post-heat-shrunk fiber layer and the fibers constituting the additional layer, bonding due to the fibers constituting the post-heat-shrunk fiber layer and the fibers constituting the additional layer being continuous, bonding by fusion of the fibers constituting the post-heat-shrunk fiber layer and the fibers constituting the additional layer, bonding by adhesion of the post-heat-shrunk fiber layer and the additional layer, and any combination thereof.

[0081] The nonwoven fabric according to the present disclosure may further include, as the additional layer, a hydrophilic fiber layer containing hydrophilic fibers bonded to the second surface of the heat-shrunk fiber layer. When the nonwoven fabric is used in an absorbent article, the hydrophilic fiber layer can diffuse menstrual blood that has permeated the nonwoven fabric (liquid-permeable sheet) in the planar direction and facilitate the transfer of menstrual blood to a member adjacent to the menstrual blood retention member.

[0082] The hydrophilic fibers constituting the hydrophilic fiber layer may be the same as the hydrophilic fibers constituting the hydrophilic region, and the hydrophilic fibers constituting the hydrophilic fiber layer and the hydrophilic fibers constituting the hydrophilic region may be the same or different.

[0083] The hydrophilic fiber layer may extend in one or both of the first and second directions, and preferably extends in the first direction, thereby diffusing menstrual blood in the direction in which the hydrophilic fiber layer extends.

[0084] The hydrophilic fiber layer may have a plurality of protrusions protruding in the thickness direction from the second surface of the heat-shrunk fiber layer and extending in the first direction. Furthermore, preferably at least a portion of the plurality of protrusions, and more preferably all of the plurality of protrusions (each of the plurality of protrusions) are arranged so as to overlap the hydrophobic regions in a plan view of the nonwoven fabric in the thickness direction. This allows, when the nonwoven fabric is used in an absorbent article, menstrual blood that has passed through the hydrophilic regions in the thickness direction of the nonwoven fabric to be easily transferred via the protrusions to a member adjacent to the menstrual blood retention member side. Furthermore, the protrusions arranged so as to overlap the hydrophobic regions allow menstrual blood to be easily transferred to a region of the member adjacent to the menstrual blood retention member side that overlaps with the hydrophobic region in the thickness direction.

[0085] Furthermore, preferably at least a portion of the plurality of protrusions, and more preferably all of the plurality of protrusions (each of the plurality of protrusions), are arranged so as to overlap a portion of the plurality of hydrophilic regions in a plan view in the thickness direction of the nonwoven fabric, so that when the nonwoven fabric is used in an absorbent article, menstrual blood that has passed through the hydrophilic regions in the thickness direction of the nonwoven fabric is more likely to migrate via the protrusions to regions of the member adjacent to the menstrual blood retention member side that overlap with the hydrophobic regions in the thickness direction.

[0086] Also, for the same reason, preferably at least a portion of the plurality of protrusions, and more preferably all of the plurality of protrusions (each of the plurality of protrusions), are arranged so as to overlap with a hydrophilic region adjacent to one side of the second direction and a hydrophilic region adjacent to the other side of the second direction when viewed in a plane from the thickness direction of the nonwoven fabric.

[0087] The nonwoven fabric according to the present disclosure can be a nonwoven fabric known in the art, such as a spunlace nonwoven fabric or a needle-punched nonwoven fabric. Preferably, the nonwoven fabric is a spunlace nonwoven fabric. This makes it easier to ensure the thickness of the nonwoven fabric compared to a nonwoven fabric with compressed portions.

[0088] The nonwoven fabric according to the present disclosure may have heat-sealed portions in which the heat-shrunk fibers are fused to other fibers, or may not have the heat-sealed portions, but it is preferable that the nonwoven fabric does not have the heat-sealed portions, which makes it easier to ensure the thickness of the nonwoven fabric compared to nonwoven fabrics that have heat-sealed portions.

[0089] The nonwoven fabric according to the present disclosure can contain the heat-shrunk fibers (heat-fusible fibers) and hydrophilic fibers in any mass ratio. The nonwoven fabric according to the present disclosure can contain the heat-shrunk fibers (heat-fusible fibers) and hydrophilic fibers in a mass ratio of preferably 40 to 90:10 to 60, more preferably 45 to 85:15 to 55, and even more preferably 50 to 80:20 to 50, relative to 100 parts by mass of the total of the heat-shrunk fibers and hydrophilic fibers. This makes it difficult for the nonwoven fabric to be discolored red by menstrual blood when used in an absorbent article, and also makes it easier to conceal menstrual blood that has migrated into the absorbent article.

[0090] The nonwoven fabric may have any thickness, but is preferably 0.3 mm or more, and more preferably 0.5 mm or more. The nonwoven fabric is also preferably 2.5 mm or less, and more preferably 2.0 mm or less. This allows the nonwoven fabric to have excellent menstrual blood concealment properties when used in absorbent articles.

[0091] In this specification, the thickness of the nonwoven fabric is measured using a thickness meter (for example, FS-60DS manufactured by Daiei Scientific Instruments Co., Ltd., measuring probe area 15 cm 2 ) to measure the area of ​​three different nonwoven fabrics (when using a thickness gauge FS-60DS, the area of ​​each part is 15 cm 2 ) at a constant pressure of 3 g / cm 2 A pressure is applied at a pressure of 100 psi, and the thickness at each site is measured 10 seconds after the pressure is applied. The same measurement is carried out for each of the 10 nonwoven fabrics, and the average value of the 30 measured values ​​in total is taken as the thickness of the nonwoven fabric.

[0092] The nonwoven fabric according to the present disclosure can have any basis weight, but preferably has a basis weight of 30 g / m 2 More preferably, 40 g / m 2 More preferably, 50 g / m 2The nonwoven fabric according to the present disclosure preferably has a basis weight of 200 g / m or more. 2 or less, more preferably 180 g / m 2 or less, and more preferably 150 g / m 2 The nonwoven fabric has the following basis weight: When used in an absorbent article, the nonwoven fabric has excellent menstrual blood concealment properties.

[0093] In the present disclosure, the basis weight of a nonwoven fabric is determined by measuring the mass of three test pieces (10 mm × 10 mm) cut out from the nonwoven fabric using a direct reading balance (for example, an electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.), and calculating the average mass of the three test pieces as the mass per unit area (g / m 2 ) means

[0094] In the nonwoven fabric according to the present disclosure, the heat shrinkage of the heat-shrunk fibers in the hydrophilic regions is preferably smaller than the heat shrinkage of the heat-shrunk fibers in the hydrophobic regions. Furthermore, the heat shrinkage of the heat-shrunk fibers in the second direction in the hydrophilic regions is preferably smaller than the heat shrinkage of the heat-shrunk fibers in the hydrophobic regions. This makes it easier for menstrual blood to migrate through the hydrophilic fibers into the absorbent article when the nonwoven fabric is used in an absorbent article, compared to when the heat shrinkage relationship is not satisfied. As a result, when the nonwoven fabric is used in an absorbent article, the nonwoven fabric is less likely to stain red and has excellent menstrual blood concealment properties.

[0095] In the nonwoven fabric according to the present disclosure, in the hydrophobic region, the heat shrinkage degree in the thickness direction of the heat-shrunk fiber and the heat shrinkage degree in the first and second directions can have any relationship, but for example, in at least a part of the hydrophobic region, the heat shrinkage degree in the thickness direction of the heat-shrunk fiber can be lower than the heat shrinkage degree in the first and second directions. As a result, when the nonwoven fabric is used in an absorbent article, the heat shrinkage degree in the thickness direction of the nonwoven fabric is relatively low compared to a case where the heat shrinkage degree is less directional, and the nonwoven fabric has excellent hiding power and feel. Note that, according to confirmation by the present inventors, when a nonwoven fabric does not have a hydrophilic region, i.e., when composed only of the heat-shrunk fiber, the heat shrinkage degree is less directional.

[0096] [Method for manufacturing nonwoven fabric] The method for manufacturing nonwoven fabric according to the present disclosure includes the following steps: - a preparation step of preparing a laminated web in which a hydrophilic fiber sheet containing the hydrophilic fibers is laminated on a heat-shrinkable fiber web containing the heat-shrinkable fibers (hereinafter may be referred to as the "preparation step") - a water jet treatment step of water jetting the laminated web from the hydrophilic fiber sheet side (hereinafter may be referred to as the "water jet treatment step") - a nonwoven fabric formation step of heating the water-jet-treated laminated web to heat-shrink the heat-shrinkable fibers and form the heat-shrunk fibers, thereby forming the nonwoven fabric (hereinafter may be referred to as the "nonwoven fabric formation step").

[0097] In the preparation step, a laminated web is prepared in which a hydrophilic fibrous sheet containing the hydrophilic fibers is laminated on a heat-shrinkable fibrous web containing the heat-shrinkable fibers. The hydrophilic fibrous sheet has a wet strength of preferably 2.0 N / 25 mm or less, more preferably 1.5 N / 25 mm or less, and even more preferably 1.0 N / 25 mm or less in any direction, particularly in both the conveying direction and the direction perpendicular to the conveying direction. This allows the nonwoven fabric according to the present disclosure to be easily formed. Note that there is no particular lower limit for the wet strength from the viewpoint of water jet treatment, but from the viewpoint of conveying the hydrophilic fibrous sheet, a lower limit of 0.3 N / 25 mm is an example.

[0098] In this specification, wet strength (N / 25 mm) is measured as follows: (1) A Tensilon tester is prepared in a constant temperature and humidity chamber at a temperature of 25±5°C and a humidity of 65±5% RH, and a sample is left standing for 24 hours. (2) A sample cut to a width of 25 mm and a length of 50 mm is impregnated with 50 μL of deionized water and left standing for 3 minutes to allow the deionized water to spread throughout the sample, forming a wet sample. (3) The wet sample is measured using the Tensilon tester with a chuck spacing of 30 mm and a tensile speed of 100 mm / min, and the tensile force (N) per 25 mm of width at break is defined as the wet strength (N / 25 mm). The wet strength is measured in accordance with JIS P 8135:1998 "Paper and paperboard -- Testing method for wet tensile strength" and JIS P 8113:2006 "Paper and paperboard -- Testing methods for tensile properties -- Part 2: Constant rate of extension method."

[0099] The hydrophilic fiber sheet may be a web, nonwoven fabric, or tissue paper containing hydrophilic fibers, which allows the nonwoven fabric according to the present disclosure to be easily formed.

[0100] In the water jet treatment step, the laminated web is water jet treated from the hydrophilic fiber sheet side. The conditions for the water jet treatment are not particularly limited as long as the nonwoven fabric according to the present disclosure can be formed using a water jet device equipped with multiple nozzles. For example, the following conditions can be mentioned:

[0101] - Inner diameter of nozzle: preferably 0.03 mm or more, more preferably 0.05 mm or more; preferably 0.17 mm or less, more preferably 0.15 mm or less - Nozzle pitch (pitch in a direction perpendicular to the conveying direction): preferably 0.3 mm or more, more preferably 0.4 mm or more; preferably 2.0 mm or less, more preferably 1.5 mm or less - Distance between nozzle and laminated web: preferably 10 mm or more, more preferably 20 mm or more; preferably 60 mm or less, more preferably 50 mm or less - Nozzle water pressure: preferably 1 MPa or more, more preferably 2 MPa or more; preferably 15 MPa or less, more preferably 13 MPa or less

[0102] The water jet treatment is typically performed by placing the laminate web on a support. The support can be any support commonly used in the art, and examples include mesh-like support members. The mesh-like support member can be a plain-woven or twill-woven mesh of thin wire-like support members (e.g., resin wires, metal wires). The opening diameter of the mesh-like support member is preferably 0.2 mm or more, and more preferably 0.25 mm or more. The opening diameter of the mesh-like support member is preferably 0.6 mm or less, and more preferably 0.45 mm or less. This facilitates the formation of the nonwoven fabric according to the present disclosure.

[0103] In the nonwoven fabric forming step, the water-jet-treated laminated web is heated to heat-shrink the heat-shrinkable fibers to form the heat-shrunk fibers, thereby forming the nonwoven fabric. In the nonwoven fabric forming step, it is preferable that the heat-shrinkable fibers are heat-shrunk to form a nonwoven fabric that is thicker than the water-jet-treated laminated web. This allows the formed nonwoven fabric to have excellent hiding power and a soft feel.

[0104] In addition, if the hydrophilic fiber is made to penetrate the heat-shrinkable fiber under the water jet conditions in the water jet treatment step, and then the heat-shrinkable fiber is heat-shrunk in the nonwoven fabric formation step, the water-jet treated laminate web will be less likely to heat-shrink in the orthogonal direction. Therefore, if the conveying speed of the water-jet treated laminate web in the nonwoven fabric formation step is adjusted (specifically, the conveying speed of the nonwoven fabric after heating is made slower than the conveying speed of the water-jet treated laminate web before heating), the heat-shrinkable fiber (fiber after heat-shrinkage) will be more likely to gather in the thickness direction, and the nonwoven fabric will be thicker than the laminate web.

[0105] Fig. 2 is a diagram showing a manufacturing apparatus 101 used to manufacture the nonwoven fabric 1 according to the first embodiment. A method for manufacturing the nonwoven fabric 1 according to the first embodiment will be described with reference to Fig. 2. As shown in Fig. 2, the manufacturing apparatus 101 includes a first carding machine 107 that inputs heat-shrinkable fibers 103 from a feeder to form a heat-shrinkable fiber web 105, and a second carding machine 111 that inputs hydrophilic fibers 13 from a feeder to form a hydrophilic fiber sheet 109.

[0106] In the manufacturing apparatus 101, a hydrophilic fiber sheet 109 formed by a second carding machine 111 is laminated on a heat-shrinkable fiber web 105 formed by a first carding machine 107 to form a laminated web 113.

[0107] A conveyor belt 115 and a water jet device 121 are disposed downstream of the first carding machine 107 and the second carding machine 111. The water jet device 121 includes a first suction drum 123 and a second suction drum 125 that rotate about their axes to suck and hold the transported laminated web 113 against their outer circumferential surfaces, a plurality of nozzles 127 that spray water and are disposed outside the first suction drum 123 so as to sandwich the laminated web 113 therebetween, a conveyor belt 129, and a dewatering machine 131. The dewatering machine 131 includes a conveyor belt 131a and a plurality of suction boxes 131b.

[0108] The laminate web 113 is transported by a transport belt 115, and water is sprayed onto the laminate web 113 from multiple nozzles 127 to form a water-jet-treated laminate web 133. In the water-jet-treated laminate web 133, the hydrophilic fibers in the portions of the hydrophilic fiber sheet 109 where the water is sprayed penetrate into the heat-shrinkable fiber web 105, and these penetrated hydrophilic fibers will later form multiple hydrophilic regions 7. In the water-jet-treated laminate web 133, the hydrophilic fibers in the portions of the hydrophilic fiber sheet 109 where the water is not sprayed remain as they are, and these remaining portions will later form the protrusions 15 of the hydrophilic fiber layer 11. The sprayed water and moisture retained by the water-jet-treated laminate web 133 are recovered from the first suction drum 123, the second suction drum 125, and the multiple suction boxes 131b.

[0109] The manufacturing apparatus 101 is equipped with a heating device 141 downstream of the dehydrator 131. The water-jet-treated laminated web 133 is heated in the heating device 141 at a predetermined heat shrinkage temperature, causing the heat-shrinkable fibers to heat shrink, forming a nonwoven fabric 1, which is then wound up by a winder 151.

[0110] The present disclosure will be described below using examples, but the present disclosure is not limited to these examples. [Production Example 1] Nonwoven fabric No. 1 was produced using the production apparatus 101 shown in Figure 2. The conditions were as follows: Heat-shrinkable fiber 103: Potentially crimpable fiber (side-by-side composite fiber made of PET and low-melting-point PET, average fiber length: 51 mm, fineness: 2.2 dtex) Heat-shrinkable fiber web 105: Basis weight: 50 g / m 2 - Hydrophilic fiber 13: softwood pulp fiber - Hydrophilic fiber sheet 109: tissue (basis weight: 20 g / m 2 )

[0111] - Nozzle inner diameter: 0.10 mm - Nozzle pitch: 1.0 mm - Distance: 50 mm - Water pressure: 7 MPa - Heat shrink temperature: 140°C

[0112] The basis weight of Nonwoven Fabric No. 1 is 72.4 g / m 2The thickness was 1.76 mm. Figure 3 shows an image of the cross section of nonwoven fabric No. 1, whose hydrophilic fibers were dyed with a blue dye. Figure 4 shows an image of the second side of nonwoven fabric No. 1. In Figure 4, the hydrophilic fibers are not dyed. A simple absorbent body was placed on a liquid-impermeable sheet, and nonwoven fabric No. 1 was placed on top of that so that its first side was the skin-contacting surface, thereby forming simple absorbent article No. 1. The simple absorbent body had a basis weight of 400 g / m 2 An absorbent core made of softwood pulp fiber is coated with a hot melt adhesive. Basis weight: 14 g / m 2 The tissue was covered with a core wrap and an embossed portion was formed.

[0113] [Manufacturing Example 2] The hydrophilic fiber 13 was changed from "softwood pulp fiber" to "rayon fiber (average fiber length: 40 mm, fineness: 1.7 dtex)", and the hydrophilic fiber sheet 109 was changed from "tissue" to "rayon fiber web (basis weight: 20 g / m 2 Nonwoven fabric No. 2 and simple absorbent article No. 2 were produced in the same manner as in Production Example 1, except that the weight of the nonwoven fabric No. 2 was changed to "100g / m²." The basis weight of nonwoven fabric No. 2 was 85.3 g / m². 2 The thickness was 1.80 mm. Figure 5 shows an image of the cross section of nonwoven fabric No. 2, in which the hydrophilic fibers were colored with a blue dye.

[0114] Comparative Production Example 3 The hydrophilic fiber 13 was changed from "softwood pulp fiber" to "latently crimpable fiber (side-by-side composite fiber made of PET and low-melting point PET, average fiber length: 51 mm, fineness: 2.2 dtex)", and the hydrophilic fiber sheet 109 was changed from "tissue" to "heat-shrinkable fiber web 105 (basis weight: 20 g / m 2 Nonwoven fabric No. 3 and simple absorbent article No. 3 were produced in the same manner as in Production Example 1, except that the weight of the nonwoven fabric No. 3 was changed to "1.5 g / m²." The basis weight of nonwoven fabric No. 3 was 71.5 g / m². 2 and the thickness was 0.82 mm.

[0115] Comparative Production Example 4 An air-through nonwoven fabric (basis weight: 28 g / m) made of heat-fusible fibers (core: polyethylene terephthalate, sheath: polyethylene, average fiber length: 51 mm, fineness: 2.8 dtex) which is generally used as a liquid-permeable top sheet of an absorbent article was prepared. 2 ) was prepared and designated as nonwoven fabric No. 4. Furthermore, nonwoven fabric No. 4 was used to form simple absorbent article No. 4 in the same manner as in Production Example 1.

[0116] Comparative Production Example 5 Nonwoven fabric No. 5 and simple absorbent article No. 5 were produced in the same manner as Production Example 1, except that the heat-shrinkable fiber was not heat-shrunk. The basis weight of nonwoven fabric No. 5 was 66.6 g / m 2 The thickness was 1.09 mm. Figure 6 shows an image of the cross section of nonwoven fabric No. 5, in which the hydrophilic fibers were colored with a blue dye.

[0117] [Example 1] A menstrual blood absorption test was conducted on simple absorbent articles No. 1 to No. 5. The procedure for the absorption test was as follows. [Absorption Test] (1) Using a color difference meter, the initial color (L * a * b * (2) Prepare an acrylic plate measuring 200 mm x 100 mm (longitudinal x transverse) and having a 40 mm x 10 mm (longitudinal x transverse) hole in the center. (3) Place the acrylic plate on top of the simple absorbent article so that the center of the simple absorbent article and the center of the hole in the acrylic plate are aligned.

[0118] (4) 3 mL of horse blood (first time) is poured into the hole in the center of the acrylic plate. (5) 30 seconds after the 3 mL of horse blood (first time) is poured, 3 mL of horse blood (second time) is poured into the hole in the center of the acrylic plate. (6) 60 seconds after the 3 mL of horse blood (first time) is poured, the acrylic plate is removed from the simple absorbent article, and a post-test photograph of the simple absorbent article is taken, and the post-test color (L * a * b * (7) Measure the initial color (L * a * b * ) and post-test color (L * a * b* (8) 90 seconds after 3 mL of horse blood (first time) was added, 10 pieces of filter paper with the initial mass m0 (g) measured were placed on top of the 10 pieces of filter paper, and a 525 g weight (bottom size 50 mm x 35 mm) was placed on top of the 10 pieces of filter paper.

[0119] (9) One minute after placing the weight, the weight and filter paper are removed, and the post-test mass m1 (g) of 10 filter papers is measured. (10) The rewetting rate R (mass%) is calculated using the following formula: R (mass%) = 100 x (m1 - m0) / 6. For simplicity, horse blood was assumed to have a specific gravity of 1 g / mL. The color difference (ΔE) and rewetting rate of Simple Absorbency No. 1 to No. 5 are shown in Table 1, and photographs of Simple Absorbency No. 1 to No. 5 after absorbing horse blood are shown in Figures 7 to 11, respectively.

[0120]

[0121] It can be seen that nonwoven fabrics No. 1 and No. 2 have superior hiding power and are less prone to rewetback than nonwoven fabric No. 4.

[0122] REFERENCE SIGNS LIST 1 Nonwoven fabric 3 Heat-shrunk fiber layer 5 Heat-shrunk fiber 7 Hydrophilic region 9 Hydrophobic region 9a One-side hydrophobic region 9b Other-side hydrophobic region 11 Hydrophilic fiber layer 13 Hydrophilic fiber 15 Projection D1 First direction D2 Second direction T Thickness direction S1 First surface S2 Second surface P Pitch

Claims

1. A nonwoven fabric for a liquid-permeable sheet of an absorbent article that absorbs menstrual blood, comprising a heat-shrunk fiber layer containing heat-shrunk fibers having hydrophobicity, and having a first direction, a second direction, and a thickness direction that are orthogonal to each other, wherein the heat-shrunk fiber layer has a first surface and a second surface, in the heat-shrunk fiber layer, the heat-shrunk fibers extend in the first direction and the second direction, the heat-shrunk fiber layer includes a plurality of hydrophilic regions and a hydrophobic region, the plurality of hydrophilic regions extend continuously or intermittently in a direction along the first direction, are spaced apart in the second direction, and in each of the plurality of hydrophilic regions, hydrophilic fibers penetrate the heat-shrunk fibers in the thickness direction from the first surface to the second surface, and in the hydrophobic region, the heat-shrunk fibers are disposed on the first surface. A nonwoven fabric characterized by the above.

2. The nonwoven fabric according to claim 1, wherein in at least a part of the plurality of hydrophilic regions, one-side hydrophobic regions, which are the hydrophobic regions existing on one side in the second direction of the hydrophilic region, and the other-side hydrophobic regions, which are the hydrophobic regions existing on the other side in the second direction of the hydrophilic region, are connected by the heat-shrunk fibers continuously arranged between the one-side hydrophobic region and the other-side hydrophobic region.

3. The nonwoven fabric according to claim 1 or 2, wherein in the hydrophobic region, in the thickness direction, the heat-shrunk fibers are disposed from the first surface to the second surface.

4. The nonwoven fabric according to any one of claims 1 to 3, further comprising a hydrophilic fiber layer containing hydrophilic fibers, which is joined to the second surface of the heat-shrunk fiber layer.

5. The hydrophilic fiber layer includes a plurality of protruding portions that protrude in the thickness direction from the second surface of the heat-shrunk fiber layer and extend in a direction along the first direction. At least a part of the plurality of protruding portions is arranged so as to overlap the hydrophobic region in a plan view from the thickness direction of the nonwoven fabric. The nonwoven fabric according to claim 4.

6. The nonwoven fabric according to claim 5, wherein at least a part of the plurality of protruding portions is arranged so as to further overlap a part of the plurality of hydrophilic regions in a plan view from the thickness direction of the nonwoven fabric.

7. The nonwoven fabric according to any one of claims 1 to 6, wherein the plurality of hydrophilic regions are arranged so as to have a pitch in the second direction of 0.3 to 2.0 mm.

8. The nonwoven fabric according to any one of claims 1 to 7, wherein the nonwoven fabric is a spunlace nonwoven fabric.

9. The nonwoven fabric according to any one of claims 1 to 8, wherein the nonwoven fabric does not include a heat-sealed portion where the fibers are heat-sealed after heat shrinkage.

10. The nonwoven fabric according to any one of claims 1 to 9, wherein the hydrophilic fiber is a cellulose-based fiber.

11. The nonwoven fabric according to any one of claims 1 to 10, wherein the nonwoven fabric has a thickness of 0.3 to 2.5 mm.

12. An absorbent article comprising the nonwoven fabric according to any one of claims 1 to 11 as a liquid-permeable sheet.

13. A method for manufacturing the nonwoven fabric according to any one of claims 1 to 11, comprising: a preparation step of preparing a laminated web in which a hydrophilic fiber sheet containing the hydrophilic fibers is laminated on a heat-shrinkable fiber web containing the heat-shrinkable fibers; a water jet treatment step of subjecting the laminated web to water jet treatment from the hydrophilic fiber sheet side; and a nonwoven fabric forming step of heating the water jet-treated laminated web to heat-shrink the heat-shrinkable fibers to form the heat-shrunk fibers, thereby forming the nonwoven fabric.

14. The method according to claim 13, wherein the hydrophilic fiber sheet has a wet strength of 2.0 N / 25 mm or less in any direction.

15. The method according to claim 13 or 14, wherein the hydrophilic fiber sheet is a web, nonwoven fabric, or tissue paper containing the hydrophilic fibers.

16. In the water jet treatment step, while conveying the laminated web in the conveying direction, a water jet device in which a plurality of nozzles having an inner diameter of 0.03 to 0.17 mm are arranged at a pitch in the orthogonal direction orthogonal to the conveying direction of 0.3 to 2.0 mm is arranged such that the distance between the plurality of nozzles and the laminated web is 10 to 60 mm, and water is sprayed onto the laminated web from the plurality of nozzles at a water pressure of 1 to 15 MPa to subject the laminated web to water jet treatment. The method according to any one of claims 13 to 15.

17. The method according to any one of claims 13 to 16, wherein in the nonwoven fabric forming step, the nonwoven fabric having a thickness greater than that of the laminated web subjected to the water jet treatment is formed by thermally shrinking the heat-shrinkable fibers.

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