Synthetic fibers for the outer layer of absorbent materials and absorbent materials that include synthetic fibers as an outer layer.

Abstract

The purpose of the present disclosure is to provide a non-woven fabric for an outer covering sheet of an absorbent article, which is not prone to inducing a feeling of mustiness between an absorbent article and clothing on the part of a user. This non-woven fabric comprises the following configuration. In this non-woven fabric (13) for an outer covering sheet (6) of an absorbent article (1), said absorbent article comprising a liquid-impermeable sheet (5) which is moisture-permeable: the non-woven fabric (13) has a thickness direction (T), a planar direction (P), a first face (15), and a second face (17); the non-woven fabric (13) includes thermoplastic resin fibers (19), and cellulosic fibers (21), at least a portion whereof configures a plurality of fiber masses (23); the non-woven fabric (13) further comprises a plurality of spaces (27) which are adjacent to first regions (25) of each of the plurality of fiber masses (23), said first regions (25) facing the first face (15); and each of the plurality of fiber masses (23) is not bonded to the thermoplastic resin fibers (19).

Description

Nonwoven fabric for the outer wrapper sheet of an absorbent article, and an absorbent article including the nonwoven fabric as the outer wrapper sheet The present disclosure relates to a nonwoven fabric for the outer wrapper sheet of an absorbent article, and an absorbent article including the nonwoven fabric as the outer wrapper sheet. In absorbent articles such as disposable diapers and sanitary napkins, in order to obtain a sense of security with natural materials, etc., nonwoven fabrics containing cotton, which is a natural fiber, have been studied as materials constituting the absorbent article. As such a nonwoven fabric, for example, Patent Document 1 describes a nonwoven fabric including hydrophobic fibers and hydrophilic fibers shorter than the hydrophobic fibers, wherein the hydrophobic fibers are heat-fused to each other, and at least a part of the hydrophilic fibers forms an aggregate and is dispersed in the sheet, and at least a part of the hydrophilic fibers of the aggregate is fused to the surface of the hydrophobic fibers, and an absorbent article including the surface layer is described. Japanese Patent Application Laid-Open No. 2002-651 The surface layer described in Patent Document 1 is intended to provide an absorbent article that allows a large amount of liquid to easily permeate into the absorbent layer, and is also likely to retain a small amount of liquid within the surface layer, making it difficult to give a moist feeling to the wearer's skin and having a good wearing feeling. It is an invention mainly focusing on the retention of liquid, and in Comparative Example 1, there is no description regarding using the above surface layer as the outer wrapper sheet. An object of the present disclosure is to provide a nonwoven fabric for the outer wrapper sheet of an absorbent article that discharges moisture from a liquid-impermeable sheet and confines the moisture within the outer wrapper sheet, so that the wearer is less likely to feel stuffiness between the absorbent article and the clothing. The present inventors have found a nonwoven fabric for the outer wrapper sheet of an absorbent article provided with a liquid-impermeable sheet having moisture permeability, the nonwoven fabric having a thickness direction, a planar direction, a first surface, and a second surface, the nonwoven fabric including thermoplastic resin fibers and cellulose-based fibers, at least a part of which forms a plurality of fiber masses, the nonwoven fabric having a plurality of voids adjacent to a first region of each of the plurality of fiber masses facing the first surface, and each of the plurality of fiber masses not being joined to the thermoplastic resin fibers. The nonwoven fabric for the outer wrapper sheet of the absorbent article according to the present disclosure allows moisture to be discharged from the liquid-impermeable sheet and confines the moisture within the outer wrapper sheet, making it difficult for the wearer to feel stuffiness between the absorbent article and the clothing. FIG. 1 is a front-side development view of an absorbent article 1 including a nonwoven fabric according to the first embodiment as an outer wrapper sheet 6. FIG. 2 is a back-side development view of the absorbent article 1 including the nonwoven fabric according to the first embodiment as the outer wrapper sheet 6. FIG. 3 is a partial end view at the III-III end face of FIG. 1. FIG. 4 is a partial enlarged view of the outer wrapper sheet 6 in FIG. 3. FIG. 5 is a diagram for explaining a nonwoven fabric 13 according to another embodiment (second embodiment) of the present disclosure. FIG. 6 is a perspective view of a shaped nonwoven fabric 113 according to the third embodiment. FIG. 7 is a plan view of the shaped nonwoven fabric 113. FIG. 8 is a cross-sectional view at the VIII-VIII cross section of FIG. 7. FIG. 9 is a cross-sectional view at the IX-IX cross section of FIG. 7. FIG. 10 is a cross-sectional view at the X-X cross section of FIG. 7. FIG. 11 is an image of the nonwoven fabric No. 1 manufactured in Production Example 1 taken by a three-dimensional measurement X-ray CT apparatus. [Definition] ・ “Outer surface” and “inner surface” In this specification, “outer surface” and “inner surface” are terms used for a single member, and respectively mean a surface far from the wearer's skin and a surface close to the wearer's skin with reference to the time of wearing. ・Regarding the “joining” of fiber masses and thermoplastic resin fibers In this specification, the terms “joining” and “joined” regarding fiber masses and thermoplastic resin fibers mean “fusion bonding” and “fusion bonded”. Therefore, “each of the plurality of fiber masses is not joined to the thermoplastic resin fibers” means “each of the plurality of fiber masses is not fusion bonded to the thermoplastic resin fibers”. Therefore, the entanglement (entangled) between the cellulosic fibers constituting the fiber mass and the thermoplastic resin fibers and / or cellulosic fibers constituting the matrix is not included in the above “joining (joined)”, and the nonwoven fabric of the present disclosure may include the entanglement between the cellulosic fibers constituting the fiber mass and the thermoplastic resin fibers and / or cellulosic fibers constituting the matrix. Note that in the above entanglement, the cellulose fibers constituting the fiber mass enter the matrix without fusing with the thermoplastic resin fibers and / or cellulose fibers constituting the matrix, or the thermoplastic resin fibers and / or cellulose fibers constituting the matrix enter the fiber mass without fusing with the cellulose fibers constituting the fiber mass, and the like. ・Regarding the "joining" of thermoplastic resin fibers to each other In this specification, the terms "joining" and "being joined" with respect to thermoplastic resin fibers mean "fusing" and "being fused", similar to the cases of the fiber mass and thermoplastic resin fibers. The present disclosure relates to the following aspects. [Aspect 1] A nonwoven fabric for an outer sheet of an absorbent article including a liquid-impermeable sheet having moisture permeability, wherein the nonwoven fabric has a thickness direction, a planar direction, a first surface, and a second surface, the nonwoven fabric includes thermoplastic resin fibers and cellulose fibers, at least a part of which constitutes a plurality of fiber masses, the nonwoven fabric includes a plurality of voids adjacent to a first region facing the first surface of each of the plurality of fiber masses, each of the plurality of fiber masses is not joined to the thermoplastic resin fibers, the nonwoven fabric. Since the nonwoven fabric includes a fiber mass of cellulose fibers and voids adjacent to the first region of the fiber mass, under non-pressure, moisture released from the absorbent body, passing through the liquid-impermeable sheet having moisture permeability, and about to be discharged to the outside of the absorbent article is concentratedly (spottily) absorbed and held by the fiber mass through the voids. Therefore, in the planar direction of the nonwoven fabric, the area of the portion holding moisture can be reduced (made spotty). Accordingly, while allowing the moisture released from the absorbent body to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. Also, even under pressure such as body pressure, since the voids are preferentially compressed more than the fiber mass, the fiber mass is released from the absorber, passes through the liquid-impermeable sheet having moisture permeability, and moisture that is about to be discharged to the outside of the absorbent article is absorbed and held intensively (spotwise) through the remaining voids. Therefore, in the planar direction of the nonwoven fabric, the area of the portion that holds moisture can be reduced (made spotwise). Accordingly, even under pressure, while allowing the moisture released from the absorber to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. From the above, the nonwoven fabric makes it difficult for moisture, which is a gas, to be discharged from the absorber to the outside of the absorbent article both under non-pressure and under pressure, and can prevent moisture from accumulating in the region between the absorbent article and the wearer's clothing, that is, outside the absorbent article and inside the wearer's clothing, making it difficult for the wearer to feel stuffy. The nonwoven fabric can absorb and hold the liquid when the fiber mass of the cellulosic fiber is released from the absorber and there is a liquid that is about to be discharged to the outside of the absorbent article through the liquid-impermeable sheet having moisture permeability under non-pressure. Also, when the outside air temperature is low, moisture that has passed through the liquid-impermeable sheet having high moisture permeability may condense on the outer surface of the liquid-impermeable sheet to generate condensed water, but the fiber mass of the cellulosic fiber can absorb and hold the liquid. The fiber mass is not joined to the thermoplastic resin fiber, and since the fiber mass can mainly move in the thickness direction (toward the first surface) within the voids, it is difficult for the fiber mass to maintain a state of contacting the thermoplastic resin fiber for a long time, and the liquid held by the fiber mass is less likely to move to the outer surface of the nonwoven fabric (the outer surface of the outer sheet) through the thermoplastic resin fiber. Therefore, the nonwoven fabric makes it difficult for the wearer to feel a wet feeling on the outer surface of the outer sheet. In addition, in the nonwoven fabric, under pressure, the voids are preferentially compressed rather than the fiber masses, so the fiber masses are difficult to be crushed, and the liquid held by the fiber masses is difficult to be extruded outside the fiber masses. Further, since the fiber masses are not joined to the thermoplastic resin fibers, the liquid extruded from the fiber masses is difficult to move to the outer surface of the nonwoven fabric (the outer surface of the outer packaging sheet) through the thermoplastic resin fibers. Therefore, the nonwoven fabric makes it difficult for the liquid to move to the outer surface of the outer packaging sheet under non-pressure and pressure, and it is difficult for the wearer to feel a wet feeling on the outer surface of the absorbent article. [Aspect 2] The nonwoven fabric according to Aspect 1, comprising a matrix containing at least the thermoplastic resin fibers and the plurality of fiber masses dispersed in the matrix. In the nonwoven fabric, the fiber masses dispersed in the matrix containing the thermoplastic resin fibers can efficiently absorb and hold the moisture that permeates the nonwoven fabric and is about to be discharged from the absorber to the inside of the absorbent article through the voids, and the moisture released from the absorber is discharged through the liquid-impermeable sheet having moisture permeability while reducing the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric. [Aspect 3] The nonwoven fabric according to Aspect 1 or 2, wherein the outer edge of the voids in the planar direction is located outside the outer edge of the fiber masses in the planar direction. In the nonwoven fabric, the outer edge of the voids is outside the outer edge of the fiber masses, and the fiber masses can absorb and hold the moisture that is released from the absorber through the voids from the entire first region and is about to be discharged to the outside of the absorbent article through the liquid-impermeable sheet having moisture permeability. Therefore, while allowing the moisture released from the absorber to be discharged through the liquid-impermeable sheet having moisture permeability, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. Further, in the nonwoven fabric, since the outer edge of the void portion is outside the outer edge of the fiber mass, the fiber mass can easily move in the void portion in the thickness direction (toward the first surface), and in both pressurized and non-pressurized states, the liquid held by the fiber mass is less likely to move through the thermoplastic resin fibers to the outer surface of the nonwoven fabric (the outer surface of the exterior sheet). [Aspect 4] The nonwoven fabric according to any one of Aspects 1 to 3, further comprising a void portion adjacent to a second region facing the second surface of at least a part of the plurality of fiber masses. Since the nonwoven fabric further includes a void portion adjacent to the second region facing the second surface of at least a part of the plurality of fiber masses, under non-pressurized conditions, the fiber mass is released from the absorber through the void portion from its first and second regions, and can absorb and hold moisture that attempts to pass through the liquid-impermeable sheet having moisture permeability and be discharged to the outside of the absorbent article. Therefore, while allowing the moisture released from the absorber to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. Further, in the nonwoven fabric, although the void portions adjacent to the first and second regions of the fiber mass are preferentially compressed more than the fiber mass under pressure, they are likely to retain their voids. Therefore, the nonwoven fabric can absorb and hold moisture that is released from the absorber, passes through the liquid-impermeable sheet having moisture permeability, and attempts to be discharged to the outside of the absorbent article, through the void portions that are more likely to remain. Therefore, while allowing the moisture released from the absorber to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. Further, in the nonwoven fabric, since it further includes a void portion adjacent to the second region facing the second surface of at least a part of the plurality of fiber masses, the fiber mass can easily move in the void portion in the thickness direction (toward the first and second surfaces), and in both pressurized and non-pressurized states, the liquid held by the fiber mass is less likely to move through the thermoplastic resin fibers to the outer surface of the nonwoven fabric (the outer surface of the exterior sheet). [Aspect 5] The nonwoven fabric according to any one of Aspects 1 to 4, in which the above thermoplastic resin fibers are joined together. In the above nonwoven fabric, since the thermoplastic resins constituting the matrix of the nonwoven fabric are joined together, the voids formed between the matrix and the fiber mass of the cellulosic fibers are likely to retain their shape, and the above-described effects are more likely to be exhibited. [Aspect 6] The nonwoven fabric according to any one of Aspects 1 to 5, wherein the nonwoven fabric contains the cellulosic fibers at a ratio of 3 to 35% by mass. Since the above nonwoven fabric contains cellulosic fibers at a predetermined ratio, the fiber mass of the cellulosic fibers is released from the absorber, passes through the liquid-impermeable sheet having moisture permeability, and the moisture that is about to be discharged to the outside of the absorbent article is concentrated (spottily) absorbed and retained through the voids, and in the plane direction of the nonwoven fabric, the area of the portion that retains moisture can be reduced (made spotty). Therefore, while allowing the moisture released from the absorber to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. [Aspect 7] The nonwoven fabric according to any one of Aspects 1 to 6, wherein the cellulosic fibers have an average fiber length shorter than that of the thermoplastic resin fibers. In the above nonwoven fabric, since the cellulosic fibers have a fiber length shorter than that of the thermoplastic resin fibers, in the nonwoven fabric, the fiber mass of the cellulosic fibers is separated from the matrix of the thermoplastic resin fibers and is likely to exist in a dispersed state in the matrix, and the above-described effects are more likely to be exhibited. [Aspect 8] The nonwoven fabric according to any one of Aspects 1 to 7, wherein the cellulosic fibers contain organic cotton. In the above nonwoven fabric, since the cellulosic fibers contain organic cotton, users are likely to feel at ease. Also, in the above nonwoven fabric, since the cellulosic fibers contain organic cotton, the cellulosic fibers are likely to have a fiber length shorter than that of the thermoplastic resin fibers, and the above nonwoven fabric is more likely to exhibit the above-described effects. [Aspect 9] The nonwoven fabric according to any one of Aspects 1 to 8, wherein the cellulose fiber contains Hillsum cotton. In the nonwoven fabric, since the cellulose fiber contains Hillsum cotton, it is easy for the user to feel at ease. Further, in the nonwoven fabric, since the cellulose fiber contains Hillsum cotton, the cellulose fiber is likely to have a fiber length shorter than that of the thermoplastic resin fiber, and the nonwoven fabric is likely to exhibit the above-described effects. [Aspect 10] The nonwoven fabric according to any one of Aspects 1 to 9, having a multilayer structure including a clothing side layer having a clothing contact surface, and the nonwoven fabric including the plurality of fiber masses in a layer other than the clothing side layer. In the nonwoven fabric, since the fiber masses are present in a layer other than the clothing side layer of the nonwoven fabric, the fiber masses of the cellulose fiber are less likely to fall off during use. Further, in the nonwoven fabric, since the fiber masses are present in a layer other than the clothing side layer of the nonwoven fabric, the liquid absorbed and held by the fiber masses of the cellulose fiber is less likely to come into contact with the wearer, and the wearer is less likely to feel discomfort. [Aspect 11] The nonwoven fabric according to any one of Aspects 1 to 10, comprising a plurality of protruding portions protruding from the first surface toward the second surface and a plurality of recessed portions recessed from the second surface toward the first surface, and each of the plurality of protruding portions overlapping with each of the plurality of recessed portions in the thickness direction. Since the nonwoven fabric has a plurality of recessed portions that are recessed on the second surface, when used as an outer sheet, a separation region is formed between the recessed portions on the second surface and the liquid-impermeable sheet. Therefore, moisture that is released from the absorber, permeates through the liquid-impermeable sheet having moisture permeability, and is about to be discharged to the outside of the absorbent article is absorbed and retained by the cellulose-based fibers of the nonwoven fabric, particularly the fiber mass thereof, and the voids adjacent to the fiber mass, and in the separation region in order to retain the moisture in a moist state (that is, to make the voids and the separation region in a high-humidity state). A state similar to vapor-liquid equilibrium is formed between the moisture (gas phase) in the separation region and the liquid (liquid phase) absorbed and retained by the absorber, and further release of moisture from the absorber is suppressed. Therefore, it becomes difficult for the wearer to feel stuffiness in the region outside the absorbent article and inside the clothing. [Aspect 12] Each of the plurality of protruding portions constitutes a ridge portion extending in one direction. The nonwoven fabric includes a plurality of groove portions having groove bottoms between the adjacent ridge portions. Each of the plurality of groove portions is a plurality of recessed portions that are recessed in the direction from the first surface to the second surface and are intermittently arranged in the one direction at the groove bottom, and each of them has a bottom. The nonwoven fabric according to Aspect 11. When the nonwoven fabric is used as an outer sheet, a separation region can be formed between the outer sheet and the liquid-impermeable sheet. Specifically, when the nonwoven fabric is used as a liquid-permeable sheet, a separation region can be formed between the recessed portion of the outer sheet and the absorber. Further, even when the nonwoven fabric is temporarily crushed under pressure and the separation region is temporarily crushed accordingly, the shape of the nonwoven fabric easily returns to its original state and the separation region easily restores under non-pressure. Therefore, the nonwoven fabric makes it more difficult for the wearer to feel stuffiness in the region outside the absorbent article and inside the clothing over a long period of time than the nonwoven fabric of Aspect 11. [Aspect 13] An absorbent article including a liquid-permeable sheet, a liquid-impermeable sheet, an absorber, and an outer sheet in that order. The outer packaging sheet is the nonwoven fabric according to any one of Aspects 1 to 12. The absorbent article. The absorbent article has the above-described effects. [Aspect 14] The absorbent article according to Aspect 12, wherein the second surface of the nonwoven fabric constitutes the outer surface of the outer packaging sheet. In the absorbent article, since the first surface of the nonwoven fabric constitutes the inner surface of the outer packaging sheet, the void portion is arranged on the first surface side of the fiber mass, that is, on the side of the liquid-impermeable sheet. Therefore, under both pressurized and non-pressurized conditions, the fiber mass is released from the absorbent body, passes through the liquid-impermeable sheet having moisture permeability, and the moisture that tends to be discharged to the outside of the absorbent article can be concentrated (spotwise) absorbed and retained through the void portion existing on the liquid-impermeable sheet side. While allowing the moisture released from the absorbent body to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. [Aspect 15] The absorbent article according to Aspect 13 or 14, wherein the liquid-permeable sheet is the nonwoven fabric according to any one of Aspects 1 to 12. In the absorbent article, since the liquid-permeable sheet and the outer packaging sheet are the above-described nonwoven fabrics, it is difficult to discharge the moisture discharged from the absorbent body not only to the outside of the absorbent article but also to the inside of the absorbent article, and the wearer is less likely to feel stuffiness in both the region outside the absorbent article and inside the clothing and the region inside the absorbent article. The nonwoven fabric for the outer packaging sheet of the absorbent article of the present disclosure will be described in detail below. For the sake of explanation, the nonwoven fabric will be described in a state where it is used as the outer packaging sheet of the absorbent article. FIG. 1 is a developed view of an absorbent article 1 including a nonwoven fabric according to one embodiment (first embodiment) of the present disclosure as an outer wrapper sheet 6, specifically, a tape-type disposable diaper. FIG. 2 is a rear view of the absorbent article 1 including the nonwoven fabric according to the first embodiment as the outer wrapper sheet 6. FIG. 3 is a partial end view at the III-III end face of FIG. 1. FIG. 4 is a partial enlarged view in the vicinity of the outer wrapper sheet 6 of FIG. 3. Note that FIG. 4 is a diagram for schematically explaining the relationship between the thermoplastic resin fibers 19, the fiber mass 23 of the cellulose-based fibers 21, the void portion 27, etc. in the outer wrapper sheet 6 (nonwoven fabric 13), and is not intended to be construed as limiting the present disclosure. In the first embodiment, the absorbent article 1 includes a liquid-permeable sheet 3, a liquid-impermeable sheet 5, an absorber 7, and an outer wrapper sheet 6 in this order. The absorbent article 1 has a longitudinal direction L and a width direction W. In the first embodiment, as shown in FIG. 1, the absorbent article 1 includes a pair of leak barriers 201 including an elastic member 203, a fixing portion 205 for fixing the leak barrier 201 to the liquid-permeable sheet 3, an elastic member 207, a tape fastener 209, etc. Since these are known in the art, the description thereof is omitted. In the first embodiment, the outer wrapper sheet 6 includes a skin side surface 9 located on the wearer's skin side and a clothing contact surface 11 that is the surface on the opposite side of the skin side surface 9 and contacts the wearer's clothing. Note that the skin side surface 9 of the outer wrapper sheet 6 is joined to the liquid-impermeable sheet 5. As shown in FIG. 4, the nonwoven fabric 13 constituting the outer wrapper sheet 6 has a thickness direction T, a plane direction P, a first surface 15, and a second surface 17. The first surface 15 forms the skin side surface 9 of the outer wrapper sheet 6, and the second surface 17 forms the clothing contact surface 11 of the outer wrapper sheet 6. Note that FIG. 4 is shown with the vertical direction reversed from FIG. 3 for the purpose of explanation, that is, the outer wrapper sheet 6 is shown on the upper side and the liquid-impermeable sheet 5 is shown on the lower side. The nonwoven fabric 13 includes thermoplastic resin fibers 19 and cellulosic fibers 21. The cellulosic fibers 21 form a plurality of fiber masses 23, and the plurality of fiber masses 23 are arranged at intervals in the matrix of the thermoplastic resin fibers 19, that is, the plurality of fiber masses 23 are dispersed in the matrix of the thermoplastic resin fibers 19. The nonwoven fabric 13 also includes a plurality of void portions 27 adjacent to a first region 25 of each of the plurality of fiber masses 23 facing the first surface 15. Specifically, in the fiber mass 23, the cellulosic fibers 21 constituting the fiber mass 23 are not joined to the thermoplastic resin fibers 19 constituting the matrix. As shown in FIG. 4, in the nonwoven fabric 13, the outer edge EE1 of the void portion 27 in the planar direction P exists outside the outer edge EE2 of the fiber mass 23 in the planar direction P. By doing so, the fiber mass 23 can absorb and hold the moisture that is released from the absorber 7 through the void portion 27 from the entire first region 25, permeates through the liquid-impermeable sheet 5 having moisture permeability, and is about to be discharged to the outside of the absorbent article 1. Therefore, while allowing the moisture released from the absorber 7 to permeate through the liquid-impermeable sheet 5 having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article 1 through the nonwoven fabric 13 can be reduced. Further, in the nonwoven fabric 13, since the outer edge EE1 of the void portion 27 is outside the outer edge EE2 of the fiber mass 23, the fiber mass 23 can easily move in the thickness direction T (toward the first surface 15) within the void portion 27. In both pressurized and non-pressurized states, the liquid held by the fiber mass 23 is less likely to move through the thermoplastic resin fibers 19 to the outer surface of the nonwoven fabric 13 (the outer surface of the outer wrapper sheet 6). FIG. 5 is a diagram for explaining the nonwoven fabric 13 according to another embodiment (second embodiment) of the present disclosure, and is an end view corresponding to FIG. 4. It should be noted that FIG. 5 is also a diagram for schematically explaining the relationship between the thermoplastic resin fibers 19, the fiber masses 23 of the cellulosic fibers 21, the void portions 27, etc., and is not intended to be construed as limiting the present disclosure. The nonwoven fabric 13 according to the second embodiment further includes a void portion 27 adjacent to a second region 26 of each of the plurality of fiber masses 23 facing the second surface 17 of the nonwoven fabric 13. Specifically, in each individual fiber mass 23, the void portion 27 adjacent to the first region 25 and the void portion 27 adjacent to the second region 26 are connected. Since the other portions are the same as the nonwoven fabric according to the first embodiment, the description thereof is omitted. In the first and second embodiments, the nonwoven fabric 13 has a single-layer structure. However, the nonwoven fabric of the present disclosure can have a multilayer structure, for example, a two-layer structure including a clothing-side layer having a clothing contact surface and a skin-side layer disposed closer to the skin side than the clothing-side layer, or a three-layer structure including a clothing-side layer having a clothing contact surface, a skin-side layer disposed closer to the skin side than the clothing-side layer, and an intermediate layer therebetween. Examples of such nonwoven fabrics include those in which the nonwoven fabric itself has a multilayer structure and those in which the web before forming the nonwoven fabric has a multilayer structure. In such an embodiment, it is preferable that the fiber masses of the cellulosic fibers are not included in the clothing-side layer but are included in layers other than the clothing-side layer. Specifically, when the nonwoven fabric of the present disclosure has a two-layer structure of a clothing-side layer and a skin-side layer, the fiber masses of the cellulosic fibers are preferably not included in the clothing-side layer but are included in the skin-side layer. When the nonwoven fabric of the present disclosure has a three-layer structure of a clothing-side layer, an intermediate layer, and a skin-side layer, the fiber masses of the cellulosic fibers are preferably not included in the clothing-side layer but are included in the intermediate layer and / or the skin-side layer. This is from the viewpoint of the difficulty of the fiber masses detaching from the nonwoven fabric. In addition, since the liquid absorbed and held by the fiber masses of the cellulosic fibers is less likely to come into contact with the wearer on the outer surface of the absorber, it is less likely for the wearer to perceive a wet state and less likely to cause discomfort to the wearer. Furthermore, since the clothing-side layer of the nonwoven fabric of the present disclosure does not contain cellulosic fibers, it is possible to prevent a decrease in the feel of the skin and flexibility due to cellulosic fibers, for example, cotton, and the nonwoven fabric of the present disclosure can have excellent feel of the skin and flexibility. In the first and second embodiments, the nonwoven fabric 13 is a flat nonwoven fabric in which both the first surface 15 and the second surface 17 are flat. However, the nonwoven fabric of the present disclosure may be a shaped nonwoven fabric having a shaped structure. As an embodiment in which the nonwoven fabric of the present disclosure is a shaped nonwoven fabric having a shaped structure, the nonwoven fabric includes a plurality of protruding portions protruding from the first surface to the second surface (protruding on the second surface), and a plurality of recessed portions recessed from the second surface to the first surface (recessed on the first surface), and each of the plurality of protruding portions and each of the plurality of recessed portions overlap in the thickness direction of the nonwoven fabric. By doing so, when a liquid-impermeable sheet is disposed on the second surface side (when the second surface of the shaped nonwoven fabric is joined to the liquid-impermeable sheet), the recessed portion can form the above-described separation region with the absorber. 6 to 10 are diagrams for explaining a shaped nonwoven fabric 113 according to another embodiment (third embodiment) of the present disclosure, and an absorbent article 101 including the shaped nonwoven fabric 113 as an outer wrapper sheet 106. Specifically, FIG. 6 is a perspective view of a shaped nonwoven fabric 113 according to the third embodiment. FIG. 7 is a plan view of the shaped nonwoven fabric 113. FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 7. FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 7. FIG. 10 is a cross-sectional view taken along line X-X of FIG. 7. 6 and 7 show the shaped nonwoven fabric 113, and FIGS. 8 to 10 show the absorbent article 101. FIGS. 8 to 10 are shown with the outer wrapper sheet 106 on the upper side. The shaped nonwoven fabric 113 has a three-layer structure including a clothing-side layer 113a having a clothing contact surface, a skin-side layer 113c, and an intermediate layer 113b between the clothing-side layer 113a and the skin-side layer 113c. The clothing-side layer 113a is formed of thermoplastic resin fibers, and each of the intermediate layer 113b and the skin-side layer 113c includes thermoplastic resin fibers and cellulose-based fibers, at least a part of which constitutes a plurality of fiber masses. The shaped nonwoven fabric 113 has a first surface 115 that constitutes a surface on the liquid-impermeable sheet 105 side and a second surface 117 that constitutes a clothing contact surface in the absorbent article 101. In the shaped nonwoven fabric 113, each of the plurality of protruding portions protrudes from the first surface 115 toward the second surface 117, in one direction D Oextends to form the ridge portion 129. The shaped nonwoven fabric 113 includes a plurality of recessed portions 130 that are recessed in the direction from the second surface 117 to the first surface 115 along the ridge portion 129. Each of the plurality of ridge portions 129 and the plurality of recessed portions 130 overlap in the thickness direction T of the shaped nonwoven fabric 113. The shaped nonwoven fabric 113 has a one-way D O orthogonal to the other direction D A A plurality of groove portions 131 are provided between two adjacent ridge portions 129 adjacent to each other, each having a groove bottom portion 133. Each of the plurality of groove portions 131 has, at the groove bottom portion 133, a plurality of recessed portions 135 that are intermittently arranged in the one-way D o and are recessed in the direction from the second surface to the first surface, each having a bottom portion 137. Each of the plurality of recessed portions 135 is composed of a bottom portion 137 and a peripheral wall portion 139 that connects the groove bottom portion 133 and the bottom portion 137. The peripheral wall portion 139 is partitioned into a pair of first peripheral wall portions 141 arranged along the one-way D O and a pair of second peripheral wall portions 142 arranged along the other direction D A The pair of first peripheral wall portions 141 arranged along the one-way D Each of the pair of first peripheral wall portions 141 arranged along the one-way D O is provided with a hole portion 143 that penetrates from the first surface 115 to the second surface 117. In each of the plurality of recessed portions 135, the bottom portion 137 has the highest fiber density in the shaped nonwoven fabric 113. By doing so, for example, when the outside air temperature is low, moisture that has permeated through the liquid-impermeable sheet 105 having high moisture permeability may condense on the outer surface of the liquid-impermeable sheet 105 to form condensed water. However, the condensed water is captured by the bottom portion 137 having a high fiber density, and the condensed water remains at the bottom portion 137 of the outer packaging sheet 106 (shaped nonwoven fabric 113), making it difficult to be discharged to the outside of the absorbent article. The exterior sheet 106 (the shaped nonwoven fabric 113) has a separation region 145 between it and the liquid-impermeable sheet 105. Specifically, the exterior sheet 106 (the shaped nonwoven fabric 113) has a separation region 145 between the recessed portion 130 and the absorber 107. Therefore, when the liquid absorbed and held by the absorber 107 is discharged from the absorber 107 as moisture due to evaporation or the like, permeates through the liquid-impermeable sheet 105 having moisture permeability, and enters the exterior sheet 106, the cellulose-based fibers (not shown) contained in the intermediate layer 113b and the skin-side layer 113c of the exterior sheet 106 (the shaped nonwoven fabric 113) absorb and hold the moisture, and to retain the moisture in the separation region 145 in a moist state (that is, to make the separation region 145 in a high-humidity state), a state similar to vapor-liquid equilibrium is formed between the moisture (gas phase) in the separation region 145 and the liquid (liquid phase) absorbed and held by the absorber 107. While allowing the moisture to be discharged by permeating through the liquid-impermeable sheet 105 having moisture permeability from the absorber 107, the moisture is prevented from being discharged outside the exterior sheet 106, and it is possible to prevent the moisture from accumulating in the region outside the absorbent article 101 and inside the wearer's clothing. Therefore, the wearer is less likely to feel stuffy. In the exterior sheet 106 (the shaped nonwoven fabric 113), the recessed portion 130 is not joined to the liquid-impermeable sheet 105, and the portion of the groove portion 131 on the first surface 115 side is joined to the liquid-impermeable sheet 105 by an adhesive (not shown). Further, in the shaped nonwoven fabric 113, the portion of the groove bottom portion 133 of the groove portion 131 on the first surface 115 side is joined to the liquid-impermeable sheet 105 by an adhesive (not shown). The exterior sheet 106 (the shaped nonwoven fabric 113) has a curved shape protruding toward the second surface 117 side at the ridge portion 129, and has a curved shape protruding toward the first surface 115 side at the groove portion 131. That is, the shaped nonwoven fabric has a substantially corrugated cross section in which the unevenness is alternately repeated in the other direction D A in which the unevenness is alternately repeated in the other direction D. In an embodiment where the nonwoven fabric of the present disclosure is a shaped nonwoven fabric, the shaping structure may be provided not only in the overlapping region that overlaps with the absorber in the thickness direction of the absorbent article but also in the non-overlapping region that does not overlap with the absorber in the thickness direction of the absorbent article. By doing so, the moisture released from the side edges of the absorber can be confined in the separation region between the liquid-impermeable sheet and the shaped nonwoven fabric. In the other direction D of the ridge portion 129 A The pitch in is preferably 0.25 to 5.0 mm, more preferably 0.5 to 3.0 mm, and even more preferably 0.75 to 2.0 mm. If the pitch is less than 0.25 mm, the shaping structure of the shaped nonwoven fabric is too fine, and the contact area between the shaped nonwoven fabric and the wearer's skin cannot be significantly reduced, and the feel of the shaped nonwoven fabric may deteriorate. If the pitch exceeds 5.0 mm, it becomes difficult to obtain a soft feel utilizing the shaping structure. The height from the groove bottom portion 133 of the groove portion 131 to the top portion of the ridge portion 129 (the height in the thickness direction T of the nonwoven fabric) is preferably 0.25 to 5.0 mm, more preferably 0.5 to 3.0 mm, and even more preferably 0.75 to 2.0 mm. If the height is less than 0.25 mm, the protrusion of the ridge portion is small, and it becomes difficult to obtain a soft feel utilizing the shaping structure. If the height exceeds 5.0 mm, the protrusion of the ridge portion is large, and it becomes difficult to obtain a soft feel. The depth of the recess 135, that is, the distance from the groove bottom portion 133 of the groove portion 131 to the bottom portion 137 of the recess 135 is preferably 0.05 to 2.0 mm, more preferably 0.075 to 1.5 mm, and even more preferably 0.1 to 1.0 mm. If the distance is less than 0.05 mm, it becomes difficult to ensure the rigidity of the bottom portion 137, and the strength in the thickness direction of the nonwoven fabric tends to be insufficient. On the other hand, if the distance exceeds 2.0 mm, the strength in the thickness direction of the shaped nonwoven fabric tends to be insufficient. According to the third embodiment, the shaped nonwoven fabric 113 has a specific shaping structure, that is, a structure including a plurality of ridges 129, a plurality of groove portions 131 having groove bottoms 133, and a plurality of recesses 135 intermittently arranged on each groove bottom 133. Therefore, it is possible to buffer the force in the thickness direction T of the shaped nonwoven fabric 113 applied from the second surface 117 side of the shaped nonwoven fabric 113. Even when a force is applied in the thickness direction T and the shaping structure is temporarily crushed, when the force is removed, the shaping structure is likely to be restored. Further, according to the third embodiment, the shaped nonwoven fabric 113 has a specific shaping structure and can buffer the force in the thickness direction T of the shaped nonwoven fabric 113 applied from the second surface 117 side of the shaped nonwoven fabric 113. Therefore, even if the shaped nonwoven fabric 113 contains cellulose fibers, for example, cotton, sufficient flexibility can be ensured. The shaped nonwoven fabric according to the third embodiment can be manufactured according to the methods described in Japanese Patent No. 5829326, Japanese Patent No. 5829327, Japanese Patent No. 5829349, etc. In the nonwoven fabric of the present disclosure, the thermoplastic resin fiber is not particularly limited as long as it is a fiber made of a thermoplastic resin. Examples of the thermoplastic resin include 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); polyamide resins such as 6-nylon; and any combination thereof. The thermoplastic resin fiber can be hydrophilic or hydrophobic and may be hydrophilized with a hydrophilizing agent. The fineness of the thermoplastic resin fiber is not particularly limited. However, from the viewpoints of the strength, flexibility, texture, liquid permeability, etc. of the nonwoven fabric, it is generally in the range of 1.1 to 8.8 dtex, preferably 1.5 to 4.6 dtex. The average fiber length of the thermoplastic resin fiber is not particularly limited. However, from the viewpoints of the strength, flexibility, liquid permeability, etc. of the nonwoven fabric, it is usually in the range of 20 to 100 mm, preferably 35 to 65 mm. Also, when the nonwoven fabric of the present disclosure has a multilayer structure, it is preferable that the fiber diameter of the thermoplastic resin fibers contained in the layer containing the cellulose-based fibers is smaller than the fiber diameter of the thermoplastic resin fibers in the layer not containing the cellulose-based fibers. The thermoplastic resin fibers with a small fiber diameter contained in the layer containing the cellulose-based fibers are likely to be entangled with the cellulose-based fibers in the layer containing the cellulose-based fibers and the thermoplastic resin fibers in the layer not containing the cellulose-based fibers, making it less likely for delamination within the layer, delamination between layers, etc. to occur due to the dissociation of the thermoplastic resin fibers and the cellulose-based fibers, and the nonwoven fabric can maintain excellent strength. In the nonwoven fabric of the present disclosure, the cellulose-based fibers are not particularly limited as long as they are fibers containing cellulose, and examples thereof include natural cellulose fibers, regenerated cellulose fibers, purified cellulose fibers, and semi-synthetic cellulose fibers. Examples of the natural cellulose fibers include plant fibers such as seed hair fibers (e.g., cotton), bast fibers (e.g., hemp), leaf vein fibers (e.g., Manila hemp), and fruit fibers (e.g., coconut). Examples of the cotton include Gossypium hirsutum (e.g., upland cotton), Gossypium barbadense, Gossypium arboreum, and Gossypium herbaceum. Also, the cotton can be organic cotton or pre-organic cotton (trademark). Organic cotton means cotton that has been certified by GOTS (Global Organic Textile Standard). Examples of the regenerated cellulose fibers include rayon, such as viscose rayon obtained from viscose, polynosic, and modal, and fibers such as cuprammonium rayon (also referred to as "cupra") obtained from a cuprammonium solution of cellulose. Examples of the purified cellulose fibers include lyocell. Specifically, it is obtained by dissolving pulp in an aqueous solution of N-methylmorpholine N-oxide to form a spinning dope and extruding it into a dilute solution of N-methylmorpholine N-oxide to form fibers. The above purified cellulose is commercially available, for example, as Tencel (trademark). Examples of the semi-synthetic fiber include semi-synthetic cellulose, such as acetate fibers, such as triacetate and diacetate fibers. In the nonwoven fabric of the present disclosure, the cellulose-based fiber preferably has an average fiber length shorter than that of the thermoplastic resin fiber. During the production of the nonwoven fabric, the fibrillation of the cellulose-based fiber is suppressed, and fiber lumps of the cellulose-based fiber are likely to be formed. As a result, in the nonwoven fabric, the fiber lumps of the cellulose-based fiber are likely to be present in a dispersed state in the matrix of the thermoplastic resin fiber. The cellulose-based fiber preferably has an average fiber length shorter than that of the thermoplastic resin fiber, more preferably has an average fiber length of 10 to 50 mm, and even more preferably has an average fiber length of 20 to 28 mm. When the cellulose-based fiber is cotton, cotton having an average fiber length of 20.6 to 25.4 mm is called medium fiber cotton, and cotton having an average fiber length of 26.2 to 27.8 mm is called medium long fiber cotton. The cellulose-based fiber is preferably a natural cellulose fiber, more preferably cotton, even more preferably cotton, and still more preferably Hillsum cotton. This is from the viewpoints of the sense of security provided by natural materials, liquid absorbency and retention, and the like. In the present disclosure, the average fiber length of the fiber is measured according to "A7.1 Measurement of fiber length" - "A7.1.1 Method A (standard method) Measuring the length of individual fibers on a graduated glass plate" in Appendix A of JIS L 1015: 2010. Note that the above method is a test method corresponding to ISO 6989 issued in 1981. The nonwoven fabric of the present disclosure contains cellulose-based fibers, preferably in an amount of 3 to 35% by mass, more preferably 3 to 20% by mass, and even more preferably 3 to 10% by mass. Fibrous masses of the cellulose-based fibers are released from the absorber, pass through the liquid-impermeable sheet having moisture permeability, and are likely to absorb and hold moisture to be discharged to the outside of the absorbent article in a concentrated (spot-like) manner through the voids, from the viewpoint of reducing the area of the portion that holds moisture (making it spot-like) in the plane direction of the nonwoven fabric. By doing so, while allowing the moisture released from the absorber to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. When the nonwoven fabric of the present disclosure is composed of thermoplastic resin fibers and cellulose-based fibers, the thermoplastic resin fibers and the cellulose-based fibers are preferably contained in a ratio of 65 to 97% by mass and 3 to 35% by mass, more preferably 80 to 97% by mass and 3 to 20% by mass, and even more preferably 90 to 97% by mass and 3 to 10% by mass. In addition, the nonwoven fabric of the present disclosure can contain a third fiber in addition to the thermoplastic resin fibers and the cellulose-based fibers. In the nonwoven fabric of the present disclosure, it is preferable to have joining points where the thermoplastic resin fibers are joined to each other in portions other than the fibrous masses of the cellulose-based fibers. Examples of the joining points include joining points by an adhesive and melting points of the thermoplastic resin fibers. Also, in the nonwoven fabric of the present disclosure, the cellulose-based fibers may be contained in portions other than the fibrous masses of the cellulose-based fibers, for example, in the matrix of the thermoplastic resin fibers. The nonwoven fabric of the present disclosure is a nonwoven fabric for an outer sheet of an absorbent article provided with a liquid-impermeable sheet having moisture permeability, and the liquid-impermeable sheet preferably has a moisture permeability of 1,500 to 4,500 g / m 2 / 24 h, more preferably 2,000 to 4,000 g / m 2 / 24 h, and even more preferably 2,500 to 3,800 g / m 2 / 24 h. This is from the viewpoint of the effects of the present disclosure. The above moisture permeability is the value measured in accordance with "Test Method for Moisture Permeability of Moisture-proof Packaging Materials (Cup Method)" of JIS Z 0208:1976, but it is different from JIS Z 0208:1976 in the following points. (i) The point of filling 20 g of water into the moisture permeation cup instead of calcium chloride (ii) The point of measuring the moisture permeability in a thermo-hygrostat at a temperature of 40 °C and a relative humidity of 60% (iii) The point of measuring the mass reduction (discharge amount) of 20 g of water instead of the mass increase of the cup after standing for 24 hours Examples of the above liquid-impermeable sheet include films such as polyolefin-based films, and non-woven fabrics such as spunbond or spunlace non-woven fabrics. When the liquid-impermeable sheet is a film, it preferably has moisture permeability, for example, it is a moisture-permeable film. Note that the above liquid-impermeable sheet preferably has no liquid permeability. The non-woven fabric of the present disclosure generally has a basis weight in the range of 10 to 100 g / m 2 , preferably 15 to 75 g / m 2 , and more preferably 20 to 50 g / m 2 from the viewpoint of the effects of the present disclosure. Further, the non-woven fabric of the present disclosure is not particularly limited, but usually has a thickness of 0.1 to 5.0 mm, preferably 0.5 to 3.0 mm, and more preferably 0.8 to 2.0 mm from the viewpoint of the effects of the present disclosure. Note that when the non-woven fabric of the present disclosure is a shaped non-woven fabric, the above thickness means the thickness of the non-woven fabric before shaping. In this specification, the thickness (mm) of the non-woven fabric is measured as follows. Prepare FS-60DS manufactured by Daiei Kagaku Seiki Co., Ltd. [measurement surface 44 mm (diameter), measurement pressure 3 g / cm 2 , and under standard conditions (temperature 23 ± 2 °C, relative humidity 50 ± 5%), press five different parts of the absorber, measure the thickness after 10 seconds of pressing at each part, and take the average value of the five measurement values as the thickness of the absorber. In the nonwoven fabric of the present disclosure, it is preferable that the fiber masses of the cellulosic fibers are dispersed within the nonwoven fabric, and it is more preferable that the nonwoven fabric of the present disclosure includes a matrix constituting the nonwoven fabric and fiber masses of cellulosic fibers dispersed in the matrix. Moisture released from the absorber and attempting to be discharged through the liquid-impermeable sheet having moisture permeability can be concentratedly (spottily) absorbed and held at the fiber masses of the cellulosic fibers, and in the plane direction of the nonwoven fabric, the area of the portion that absorbs and holds moisture can be reduced (made spotty). Therefore, while allowing the moisture released from the absorber to pass through the liquid-impermeable sheet having moisture permeability and be discharged, the amount of moisture discharged to the outside of the absorbent article through the nonwoven fabric can be reduced. Incidentally, the matrix can be composed of the fibers included in the nonwoven fabric of the present disclosure. For example, it can be composed of thermoplastic resin fibers and cellulosic fibers, and it is preferably composed of thermoplastic resin fibers. This is from the viewpoint of the effects of the present disclosure. The nonwoven fabric of the present disclosure, for example, a nonwoven fabric having a two-layer structure including a clothing-side layer having a clothing contact surface and a skin-side layer disposed closer to the skin side than the clothing-side layer, can be manufactured according to the following manufacturing method. Incidentally, the following manufacturing method is an example of the manufacturing method of the nonwoven fabric of the present disclosure, and the nonwoven fabric of the present disclosure can be manufactured by any method. (1) Prepare a nonwoven fabric manufacturing apparatus including a conveying belt capable of conveying a sheet-like member while adjusting its tension, and along the conveying belt, a first-stage carding device, a second-stage carding device, an air-through type heating device, a compressing device including a pair of anvil rolls, and a bulk recovery device (thickness recovery device) having a heating means, in that order. (2) Supply core-sheath type thermoplastic resin fibers and cellulosic fibers to the first-stage carding device, and form a first web on the conveying belt that can open the thermoplastic resin fibers and cellulosic fibers and form a skin-side layer. By making the average fiber length of the cellulosic fibers shorter than the average fiber length of the thermoplastic resin fibers, the opening of the cellulosic fibers can be suppressed, and fiber masses of the cellulosic fibers can be more likely to remain in the first web. (3) Supply the core-sheath type thermoplastic resin fiber and the cellulose-based fiber to the carding device of the second stage, open the thermoplastic resin fiber and the cellulose-based fiber, and form a second web that can form the clothing side layer on the first web of the conveyor belt, and stack them to form a stacked web. (4) Convey the stacked web to a heating device of the air-through type, heat the stacked web at a temperature higher than the melting point of the sheath portion of the core-sheath type thermoplastic resin fiber, and thermally fuse the thermoplastic resin fibers in the first web and the second web to form a nonwoven fabric to be processed. (5) Compress the nonwoven fabric to be processed in the thickness direction using a pair of anvil rolls of a compression device, compress the thickness of the nonwoven fabric to be processed to about 10 to 40% ( = 100 × thickness of the compressed nonwoven fabric / thickness of the nonwoven fabric to be processed), and compress the matrix mainly composed of thermoplastic resin fibers and the fiber mass of cellulose-based fibers to form a compressed nonwoven fabric. Note that the compressed nonwoven fabric may be further compressed by winding it around a roll. When winding around a roll, it is preferable to further compress the thickness of the compressed nonwoven fabric to 30 to 50%. (6) By strongly applying tension in the conveying direction to the compressed nonwoven fabric, cut the fused portion formed between the thermoplastic resin fiber and the fiber mass of cellulose-based fibers to form a nonwoven fabric in which the fused portion between the cellulose-based fiber and the fiber mass is cut. (7) Convey the nonwoven fabric in which the fused portion between the cellulose-based fiber and the fiber mass is cut to a bulk recovery device, heat the nonwoven fabric, and recover the thickness of the nonwoven fabric to, for example, 130 to 200% ( = 100 × thickness of the nonwoven fabric of the present disclosure / nonwoven fabric in which the fused portion between the cellulose-based fiber and the fiber mass is cut), thereby forming a void between the thermoplastic resin fiber with an easy-to-recover thickness and the fiber mass with a difficult-to-recover thickness to form the nonwoven fabric of the present disclosure. Note that when the nonwoven fabric of the present disclosure has a three-layer structure including a clothing side layer having a clothing contact surface, a skin side layer disposed on the skin side, and an intermediate layer therebetween, a third-stage carding device can be disposed between the second-stage carding device and the air-through type heating device. Note that the method for forming the web of each layer is not limited to the above method. For example, a wet method may be adopted. Further, the method for forming the nonwoven fabric is not limited to the above method. For example, a hydroentangling method or a needle punching method may be adopted. Further, after the step (7), a nonwoven fabric shaping step may be provided according to the methods described in Japanese Patent No. 5829326, Japanese Patent No. 5829327, Japanese Patent No. 5829349, etc. The nonwoven fabric of the present disclosure is suitable for use as an outer sheet of an absorbent article. The absorbent article is not particularly limited, and examples thereof include disposable diapers, urine pads, sanitary napkins, panty liners, and the like. Hereinafter, the present disclosure will be described with examples, but the present disclosure is not limited to these examples. [Production Example 1] <Manufacture of nonwoven fabric> Two types of PET / PE core-sheath composite fibers with different finenesses (composite fiber A: fineness 2.2 dtex, average fiber length 45 mm, composite fiber B: fineness 1.7 dtex, average fiber length 45 mm) and Hillsum cotton (average fiber length of about 27 mm) were supplied to the first-stage carding device, and these fibers were opened to form a first web (skin side layer, basis weight: 13 g / m 2 , basis weight of composite fiber A and composite fiber B: 10 g / m 2 , basis weight of Hillsum cotton: 3 g / m 2 ). A PET / PE core-sheath composite fiber (fineness 2.8 dtex, average fiber length 45 mm) as a thermoplastic resin fiber was supplied to the second-stage carding device, and the PET / PE core-sheath composite fiber was opened to form a second web (clothing side layer, basis weight: 20 g / m 2 ) on the first web to form a stacked web. The stacked web was conveyed to a heating device of the air-through type, and the PET / PE core-sheath composite fibers in each web and between the webs were heat-sealed in the heating device to obtain a nonwoven fabric No. 1 to be processed. The nonwoven fabric No. 1 to be processed was compressed in the thickness direction by a pair of anvil rolls, and its thickness was compressed to approximately 20%. Next, the nonwoven fabric No. 1 to be processed was tensioned in the plane direction and then heated to recover its thickness, thereby forming the nonwoven fabric No. 1. The nonwoven fabric No. 1 was scanned with a three-dimensional measurement X-ray CT device (TDM-1000-IS / SP manufactured by Yamato Scientific Co., Ltd.) to obtain a three-dimensional image near the fiber mass. The image is shown in FIG. 11. From FIG. 11, it can be seen that there is a void portion 27 adjacent to the fiber mass 23. <Manufacture of disposable diapers> Basis weight: 220 g / m 2 of pulp and a high absorbent polymer (SAP) with a basis weight of 156 g / m 2 were mixed to obtain an absorbent material, which was coated with a tissue having a basis weight of 10 g / m 2 to obtain an absorber. On one surface of the obtained absorber, as a liquid-permeable sheet, the nonwoven fabric No. 1 was joined so that the first surface (the wearing-side layer formed from the first web) was in contact with the absorber. On the other surface of the absorber, a moisture-permeable film with a basis weight of 15 g / m 2 (moisture permeability: about 3,000 g / m 2 / 24 h) was joined as a liquid-impermeable sheet, and the nonwoven fabric No. 1 was joined outside the moisture-permeable film as an outer packaging film to obtain a laminate. For these joints, a hot-melt type adhesive (coating amount: 3 g / m 2 ) was used. Then, the obtained laminate was cut into a predetermined shape of a disposable diaper to create the disposable diaper No. 1. [Production Example 2] The nonwoven fabric No. 1 manufactured in Production Example 1 was shaped according to the method described in Japanese Patent No. 5829326 to manufacture the nonwoven fabric No. 2. Next, except that the liquid-permeable sheet and the outer packaging film were changed from non-woven fabric No. 1 to non-woven fabric No. 2, disposable diaper No. 2 was manufactured in the same manner as in Production Example 1. Note that, as the liquid-permeable sheet, non-woven fabric No. 2 was joined such that the first surface (the layer on the clothing side formed from the first web) was in contact with the absorber, and as the outer packaging film, the first surface (the layer on the clothing side formed from the first web) was in contact with the liquid-impermeable sheet. [Comparative Production Example 1] The first web (basis weight: 10 g / m 2 ), except that it was formed from a mixture of two types of PET / PE core-sheath composite fibers having different finenesses (composite fiber A with a fineness of 2.2 dtex and an average fiber length of 45 mm, and composite fiber B with a fineness of 1.7 dtex and an average fiber length of 45 mm), non-woven fabric No. 3 was formed in the same manner as in Production Example 1. Also, except that the permeable sheet and the outer packaging film were changed from non-woven fabric No. 1 to non-woven fabric No. 3, disposable diaper No. 3 was manufactured in the same manner as in Production Example 1. [Examples 1 and 2, and Comparative Example 1] In disposable diapers No. 1 to No. 3, after absorbing artificial urine, the evaporation rate (% by mass) every predetermined time was evaluated. The results are shown in Table 1. [Measurement Method of Evaporation Rate] (1) In order to eliminate the influence of the ambient environment, the sample was left standing in a thermo-hygrostat at a temperature of 20°C and a humidity of 60% RH for 5 days (120 hours). (2) The sample was taken out from the thermo-hygrostat, and the initial mass of the sample: A0 (g) was measured. (3) On a test bench having a horizontal surface, the sample was spread out such that the liquid-permeable sheet was on the top surface, and a cylinder with an inner diameter of 60 mm was placed on the liquid-permeable sheet. (4) 80 mL of artificial urine was dropped into the cylinder in 10 seconds. Note that the artificial urine was prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride, and approximately 1 g of a dye (Blue No. 1) in 10 L of ion-exchanged water. After confirming that all the artificial urine in the cylinder has been absorbed by the sample, remove the cylinder from above the liquid-permeable sheet, and immediately measure the mass of the sample after absorbing the artificial urine: A1 (g). (6)Leave the sample after absorbing the artificial urine in a certain atmosphere, and measure the mass of the sample: W1, W3, W5, W8 and W at 1 hour, 3 hours, 5 hours, 8 hours and 21 hours after removing the cylinder from above the surface sheet in the above (5). 21 (g)respectively. (7)The evaporation rate of the sample at each elapsed time: E1, E3, E5, E8 and E 21 (mass%)is calculated by the following formula (1). E N (mass%)= 100×(A1 - W N ) / (A1 - A0) (In the formula, N is 1, 3, 5, 8 or 21.) As shown in Table 1, Disposable Diaper No. 1 and No. 2 had a lower evaporation rate after absorbing artificial urine compared to Disposable Diaper No. 3, and it was found that it was less likely to get wet or stuffy. In particular, Disposable Diaper No. 1 and No. 2 had a lower evaporation rate 8 hours and 21 hours after absorbing artificial urine, and it was found that it was less likely to get wet or stuffy over a long period of time. Also, when the liquid-permeable sheet was changed to a general air-through nonwoven fabric in the technical field in Disposable Diapers No. 1 to No. 3, a similar tendency of evaporation rate was obtained as the results obtained in Example 1, Example 2, and Comparative Example 1. 1 Absorbent article 3 Liquid-permeable sheet 5 Liquid-impermeable sheet 6 Outer packaging sheet 7 Absorbent body 9 Skin side 11 Wearing contact surface 13 Nonwoven fabric 15 First surface 17 Second surface 19 Thermoplastic resin fiber 21 Cellulose-based fiber 23 Fiber mass 25 First region 26 Second region 27 Void portion 101 Absorbent article 103 Liquid-permeable sheet 105 Liquid-impermeable sheet 106 Outer packaging sheet 107 Absorbent body 113 Shaped nonwoven fabric 113a Garment side layer 113b Intermediate layer 113c Skin side layer 115 First surface 117 Second surface 129 Ridge portion 130 Depression portion 131 Groove portion 133 Groove bottom 135 Concave portion 137 Bottom 139 Peripheral wall portion 141 First peripheral wall portion 142 Second peripheral wall portion 143 Hole portion 145 Spacing region 201 Leakage prevention wall 203 Elastic member 205 Fixing portion 207 Elastic member 209 Tape fastener T Thickness direction P Plane direction EE1, EE2 Outer edge D O One direction D A The other direction

Claims

Page 1 of 2 pages of Claims 1. Synthetic fibers for the outer layer of an absorbent material comprising an impermeable, vapor-permeable sheet where the synthetic fibers are oriented in thickness and planar directions and on the first and second surfaces; the synthetic fibers include thermoplastic resin fibers and cellulose fibers, of which at least part of them form a certain number of fiber masses; the synthetic fibers comprise a certain number of voids located in proportion to the first region of each of those fiber masses facing the first surface, and each of those fiber masses is not interconnected with thermoplastic resin fibers.

2. Synthetic fibers according to Claims 1 where the synthetic fibers comprise a matrix comprising at least thermoplastic resin fibers and a certain number of fiber masses distributed within that matrix.

3. Synthetic fibers according to Claims 1 or 2 where the outer boundary of the voids in the planar direction is located further than the outer boundary of the fiber masses in the planar direction. 4.Synthetic fibers under any of Reputations 1 to 3 whereby the synthetic fibers also contain voids in a second region facing the second surface of at least some of the fiber mass.

5. Synthetic fibers under any of Reputations 1 to 4 whereby thermoplastic resin fibers are bonded together.

6. Synthetic fibers under any of Reputations 1 to 5 whereby the synthetic fibers include cellulose fibers in a ratio of 3 to 35% by mass.

7. Synthetic fibers under any of Reputations 1 to 6 whereby the cellulose fibers have a shorter average fiber length than the thermoplastic resin fibers.

8. Synthetic fibers under any of Reputations 1 to 7 whereby the cellulose fibers include organic fibers.

9. Synthetic fibers under any of Reputations 1 to 8 whereby the cellulose fibers include hygroscopic fibers. 10.Synthetic fibers according to any of the claims 1 through 9 whereby the synthetic fiber has a multi-layered structure including the garment layer along with the fabric-contacting surface and the synthetic fiber consists of a certain mass of fibers in one layer in addition to the garment layer, page 2 of number 2, page 11. Synthetic fibers according to any of the claims 1 through 10 whereby the synthetic fiber consists of a certain number of ridges protruding in the direction from the first surface to the second surface and a certain number of indentations pressed in the direction from the second surface to the first surface, each of these ridges and each of these indentations overlap in the thickness direction.

12. Synthetic fibers according to the claim 11 whereby each of these ridges forms a ridge running in one direction, the synthetic fiber consists of a certain number of creases with the crease bottom between adjacent ridges and each of these creases consists of a certain number of small crevices pressed in the direction from the first surface to the second surface, which are arranged at intervals in one direction on the crease bottom, each of them having a bottom portion.13.An adsorbent comprising a permeable pad, an impermeable pad, an adsorbent body, and an outer pad, in that order, where the outer pad is a synthetic fiber as specified in any of Claims 1 through 12; 14. An adsorbent as specified in Claim 13 where the secondary surface of the synthetic fibers constitutes the outer surface of the outer pad; 15. An adsorbent as specified in Claims 13 or 14 where the permeable pad is a synthetic fiber as specified in any of Claims 1 through 11;