Sheet member and disposable absorbent article

Abstract

Provided are: a sheet member having a nonwoven fabric layer (25a) having a plurality of non-heat-fusible fibers (25as), wherein the average fiber length of the non-heat-fusible fibers (25as) is 5 mm or more, and the standard deviation of the fiber length of the non-heat-fusible fibers is 5.5 or less; and a disposable absorbent article provided with the sheet member.

Description

Sheet material and disposable absorbent article

[0001] This invention relates to a sheet member and a disposable absorbent article.

[0002] The sheet material used in absorbent articles is a material that comes into contact with the wearer's skin and absorbs excrement, sweat, etc. For example, Patent Document 1 discloses a disposable diaper equipped with a sweat-absorbing sheet. In the diaper of Patent Document 1, the sweat-absorbing sheet is provided to come into contact with the wearer's waist in order to absorb the wearer's sweat.

[0003] Japanese Patent Publication No. 2001-327534

[0004] In sheet materials such as the sweat-absorbing sheet described in Patent Document 1, variations in the density of the fibers constituting the sheet material could lead to localized decreases in moisture absorption, uneven thickness, and localized increases or decreases in rigidity.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to reduce the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member.

[0006] The main invention for achieving the above objective is a sheet member having a nonwoven fabric layer having a plurality of non-heat-fusible fibers, wherein the average fiber length of the non-heat-fusible fibers is 5 mm or more, and the standard deviation of the fiber lengths of the non-heat-fusible fibers is 5.5 or less. Other features of the present invention will be made clear by this specification and the accompanying drawings.

[0007] According to the present invention, it is possible to provide a sheet member that reduces the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member.

[0008] Figure 1 is a schematic perspective view of diaper 1 from the ventral side. Figure 2 is a schematic plan view of diaper 1 in an unfolded and extended state, as seen from the wearer's skin side. Figure 3 is a schematic cross-sectional view along A-A in Figure 2. Figure 4 is a schematic cross-sectional view of the sheet portion 25. Figure 5A is an enlarged photograph of the sheet portion 25 as seen from the skin side. Figure 5B is an enlarged schematic view of a part of Figure 5A. Figure 6A is data showing the distribution of fiber lengths of skin-side fibers constituting the nonwoven fabric layer 25a (skin-side layer 25a) in this embodiment, and Figure 6B is data showing the distribution of fiber lengths of skin-side fibers in the sheet member of the comparative example. Figure 7A is a graph showing the fiber length distribution of Figure 6A (this embodiment), and Figure 7B is a graph showing the fiber length distribution of Figure 6B (comparative example). This is modification 1 of the arrangement of the sheet portion 25 of the present invention. This is modification 2 of the arrangement of the sheet portion 25 of the present invention. This is modification 3 of the arrangement of the sheet portion 25 of the present invention. This is modification 4 of the arrangement of the sheet portion 25 of the present invention.

[0009] The following matters will become clear from the description in this specification and the accompanying drawings: (Aspect 1) A sheet member characterized by having a nonwoven fabric layer having a plurality of non-heat-fusible fibers, wherein the average fiber length of the non-heat-fusible fibers is 5 mm or more, and the standard deviation of the fiber lengths of the non-heat-fusible fibers is 5.5 or less.

[0010] According to the sheet member of Embodiment 1, since the average fiber length of the non-heat-fusible fibers constituting the nonwoven fabric layer is 5 mm or more, the risk of non-heat-fusible fibers falling off the sheet member can be reduced compared to when the average fiber length is shorter than 5 mm. Furthermore, since the standard deviation of the fiber length of the non-heat-fusible fibers is 5.5 or less, it is easier to reduce the variation in the density of non-heat-fusible fibers in the sheet member compared to when the standard deviation of the fiber length of the non-heat-fusible fibers is greater than 5.5. As a result, the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member can be reduced.

[0011] (Aspect 2) The sheet member according to aspect 1, characterized in that, among the plurality of non-heat-fusible fibers, the non-heat-fusible fibers having a fiber length of less than 20.6 mm account for 90% by weight or more of the plurality of non-heat-fusible fibers.

[0012] According to the sheet member of embodiment 2, it is possible to make the density of non-heat-fusible fibers in the sheet member more uniform than when non-heat-fusible fibers with a fiber length of 20.6 mm or more account for more than 10% by weight of the multiple non-heat-fusible fibers. Therefore, it is possible to further reduce the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member.

[0013] (Aspect 3) The sheet member according to aspect 1 or 2, characterized in that, among the plurality of non-heat-fusible fibers, the non-heat-fusible fibers having a fiber length of 12 mm or less account for 50% by weight or more of the plurality of non-heat-fusible fibers.

[0014] According to the sheet member of embodiment 3, it is possible to make the density of non-heat-fusible fibers in the sheet member more uniform than when non-heat-fusible fibers with a fiber length of 12 mm or more account for more than 50% by weight of the multiple non-heat-fusible fibers. Therefore, it is possible to reduce the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member.

[0015] (Aspect 4) The sheet member according to any of aspects 1 to 3, characterized in that the plurality of non-heat-fusible fibers does not include any non-heat-fusible fibers with a fiber length of 35 mm or more.

[0016] According to the sheet member of embodiment 4, it is easier to make the density of non-heat-fusible fibers in the sheet member uniform compared to the case where the non-heat-fusible fibers have a fiber length of 35 mm or more. Therefore, it is easier to reduce the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member.

[0017] (Aspect 5) The sheet member is one of the sheet members of aspects 1 to 4, characterized in that no adhesive is provided on the sheet member.

[0018] According to the sheet member of embodiment 5, by forming the sheet member without using an adhesive, it is possible to suppress the hardening of the sheet member caused by the presence of an adhesive, while also reducing the risk that the adhesive may hinder the absorption of moisture.

[0019] (Aspect 6) The sheet member of aspect 5, characterized in that the non-heat-fusible fibers are intertwined with each other.

[0020] According to the sheet member of embodiment 6, the fibers become intertwined with each other, making it easier to form voids between the fibers. This reduces the risk of the sheet member becoming hard, while further reducing the risk of moisture absorption being hindered.

[0021] (Aspect 7) A sheet member according to any of aspects 1 to 6, characterized in that it does not have portions in which the non-heat-fusible fibers are fused together.

[0022] According to the sheet member of embodiment 7, by not having portions where non-heat-fusible fibers are fused together, the risk of the sheet member becoming hard is reduced, while the risk of moisture absorption being hindered by portions where non-heat-fusible fibers are fused together is also reduced.

[0023] (Aspect 8) The non-heat-fusible fiber is a cotton fiber and has a different substance from the cotton fiber, and the substance is 1 mm in thickness when viewed in the thickness direction. ２ The sheet member is characterized by having the above size, as described in any of embodiments 1 to 7.

[0024] According to the sheet member of embodiment 8, the user can more easily recognize the presence of the sheet member by visually confirming that a substance different from the cotton fibers is included in the cotton fibers.

[0025] (Aspect 9) The sheet member according to aspect 8, characterized in that the basis weight of the substance in the entire sheet member is smaller than the basis weight of the cotton fibers.

[0026] According to the sheet member of embodiment 9, by making the basis weight of the material such as seed husks smaller than that of the cotton fibers, it is possible to give the user the impression that the sheet member is made of natural materials while reducing the risk of reduced moisture absorption by the cotton fibers.

[0027] (Aspect 10) A sheet member according to any one of aspects 1 to 9, characterized in that in a layer having at least one outer surface when the sheet member is divided into three equal parts in the thickness direction, the non-heat-fusible fibers account for 90% by weight or more of the fibers constituting the sheet member.

[0028] According to the sheet member of embodiment 10, it is easier to reduce the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member on at least one surface in the thickness direction.

[0029] (Aspect 11) The sheet member according to any one of aspects 1 to 10, characterized in that the nonwoven fabric layer is a layer that can come into contact with the user's skin, and in the thickness direction, it has another layer provided on the non-skin side of the nonwoven fabric layer, the non-heat-fusible fibers are cotton fibers, 90% by weight or more of the fibers constituting the nonwoven fabric layer are a plurality of cotton fibers, and 90% by weight or more of the fibers constituting the other layer are a plurality of heat-fusible fibers.

[0030] According to the sheet member of embodiment 11, the nonwoven fabric layer on the skin side of the sheet member can easily absorb moisture such as sweat from the wearer, and the absorbed moisture can be easily moved to other layers on the non-skin side and evaporated. Therefore, it is possible to suppress stuffiness and discomfort to the wearer when the sheet member comes into contact with the wearer's skin.

[0031] (Aspect 12) The sheet member according to aspect 11, characterized in that the average fiber length of the cotton fibers is shorter than the average fiber length of the heat-fusible fibers, and the cotton fibers are entangled with the heat-fusible fibers.

[0032] According to the sheet member of embodiment 12, since the cotton fibers with a short average fiber length are covered from the non-skin side by the heat-fusible fibers with a long average fiber length, it is easier to suppress the cotton fibers from falling out to the outside (non-skin side) of the sheet member. Therefore, it is easier to maintain a uniform density of non-heat-fusible fibers in the skin-side layer of the sheet member, and the risk of a decrease in water absorption, uneven thickness, changes in rigidity, etc. can be reduced.

[0033] (Aspect 13) The sheet member according to aspect 11 or 12, characterized in that the value obtained by dividing the total weight of the cotton fibers by the weight of the sheet member is smaller than the value obtained by dividing the total weight of the heat-fusible fibers by the weight of the sheet member.

[0034] According to the sheet member of embodiment 13, it is possible to make it easier for cotton fibers with a small mass percentage to absorb moisture, while making it easier for the absorbed moisture to evaporate from the heat-fused fibers with a large mass percentage. Therefore, moisture evaporation can be improved compared to when the value obtained by dividing the total weight of the cotton fibers by the weight of the sheet member is greater than the value obtained by dividing the total weight of the heat-fused fibers by the weight of the sheet member.

[0035] (Aspect 14) A sheet member according to any of aspects 11 to 13, characterized in that the thickness of the nonwoven fabric layer is greater than the thickness of the other layers.

[0036] According to the sheet member of embodiment 14, the feel against the skin can be made softer than when the thickness of the nonwoven fabric layer on the skin-facing side that comes into contact with the wearer's skin is thinner than the thickness of the other layers. In addition, it is possible to make it easier for the cotton fibers on the skin side to absorb moisture while also improving moisture evaporation.

[0037] (Aspect 15) The sheet material has a basis weight of 30 g / m². ２ The sheet member is one of embodiments 11 to 14, characterized by the following:

[0038] According to the sheet member of embodiment 15, the sheet member tends to become harder as the basis weight of the sheet member increases, and the basis weight is 30 g / m². ２ By setting the basis weight to 30 g / m², the basis weight will be 30 g / m². ２The sheet member can be made softer than when the value is larger.

[0039] (Aspect 16) The sheet member according to any one of Aspects 11 to 15, wherein a standard deviation of fiber lengths of the heat-fusible fibers is smaller than a standard deviation of fiber lengths of the cotton fibers.

[0040] According to the sheet member of Aspect 16, while reducing variation in the density of cotton fibers in the nonwoven fabric layer, it is possible to further reduce variation in the density of heat-fusible fibers in other layers. Therefore, over the entire sheet member, it is easy to reduce the risk of partial reduction in the amount of absorbed moisture, uneven thickness of the sheet member, and partial changes in rigidity of the sheet member.

[0041] (Aspect 17) The sheet member according to any one of Aspects 11 to 16, wherein the sheet member has a machine direction and a cross direction orthogonal to the thickness direction, the nonwoven fabric layer has a predetermined basis weight portion including the cotton fibers at a predetermined basis weight, and a low basis weight portion having a lower basis weight of the cotton fibers than the predetermined basis weight portion, when viewed in the thickness direction, the sheet member has a portion where the predetermined basis weight portion overlaps the other layer and a portion where the low basis weight portion overlaps the other layer, the predetermined basis weight portions and the low basis weight portions are alternately arranged in the machine direction, the predetermined basis weight portions and the low basis weight portions are alternately arranged in the cross direction, a length of the low basis weight portion in the machine direction is shorter than an average fiber length of the cotton fibers, and a length of the low basis weight portion in the cross direction is shorter than the average fiber length of the cotton fibers.

[0042] According to the sheet member of Aspect 17, when viewed in the thickness direction, the portion where the predetermined basis weight portion overlaps the other layer absorbs moisture such as sweat from the wearer's skin, and the absorbed moisture is likely to be promoted to transpire from the low basis weight portion, and furthermore, the movement of moisture from the low basis weight portion to the non-skin-side layer (the other layer) is easily promoted. Therefore, the risk of the skin-side layer continuing to retain excessive moisture can be reduced, and the risk of occurrence of stuffiness, rough skin, and the like can be reduced. Further, since the predetermined basis weight portions and the low basis weight portions are alternately arranged in the machine direction and the cross direction, discomfort and adverse effects on the wearer's skin can be reduced over a wide range of the sheet member.

[0043] (Aspect 18) A disposable absorbent article characterized by comprising a sheet member as described in any of aspects 1 to 17.

[0044] According to the absorbent article of embodiment 18, the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member can be reduced, thereby reducing the risk of reduced absorbency and reduced feel of the disposable absorbent article.

[0045] (Aspect 19) The sheet member according to aspects 1 to 17, characterized in that the substance is at least one of a leaf, a seed husk, or a stem.

[0046] According to the sheet material of embodiment 19, when a user sees a substance such as a seed husk, it is easier to give the impression that the sheet material is made of natural materials. This makes it easier to evoke an image of being gentle on the skin and the environment, and safe.

[0047] (Aspect 20) The nonwoven fabric layer has a substance different from the cotton fibers, and the substance is 1 mm thick when viewed in the thickness direction. ２ The sheet member according to embodiments 1 to 17 is characterized by having the above size and the other layers not having the above substance.

[0048] According to the sheet member of embodiment 20, foreign matter is visible on one side in the thickness direction (skin side), while it is not visible on the other side in the thickness direction (non-skin side). Therefore, the user can easily recognize at a glance which side in the thickness direction has the nonwoven fabric layer.

[0049] ===Embodiment=== In the following description of the sheet member for absorbent articles according to this embodiment, an adult pant-type disposable diaper 1 (hereinafter also simply referred to as "diaper 1") will be used as an example of an absorbent article, and a sweat-absorbing sheet (sheet portion 25, 35) for the waist portion 20, 30 of diaper 1 will be used as an example of a sheet member. However, the absorbent article according to this embodiment is not limited to the above, and can also be applied to, for example, pant-type disposable diapers for infants, shorts-type sanitary napkins, tape-type disposable diapers, etc. Furthermore, the sheet member can be any member that can come into contact with the skin side of each absorbent article, regardless of whether it is a sweat-absorbing sheet.

[0050] <Basic Structure of the Pants-Type Disposable Diaper 1> Figure 1 is a schematic perspective view of diaper 1 as seen from the ventral side. Figure 2 is a schematic plan view of diaper 1 in its unfolded and extended state as seen from the wearer's skin side. Figure 3 is a schematic cross-sectional view of A-A in Figure 2.

[0051] The "unfolded state" of diaper 1 refers to the state in which the diaper 1, in the pant-type state shown in Figure 1, is unfastened by releasing the side joints SS (described later) on both sides in the left-right direction, thereby separating the ventral waist portion 20 (described later) and the dorsal waist portion 30 (described later), and opening the diaper 1 vertically, thereby unfolding the diaper 1 onto a flat surface. The "stretched state" of diaper 1 refers to the state in which the product (diaper 1) is stretched without wrinkles, specifically, the state in which the dimensions of each component constituting the diaper 1 (for example, the absorbent body 10 and the ventral waist portion 20, etc.) are stretched to match or be close to the dimensions of the individual component.

[0052] Diaper 1, in its pant-type state when worn as shown in Figure 1, has intersecting vertical, horizontal, and front-to-back directions, and has a waist opening BH and a pair of leg openings LH. In the vertical direction, the waist opening BH side is the upper side, and the side that is the wearer's crotch side is the lower side. In the front-to-back direction, the side that is the wearer's abdominal side is the front side, and the side that is the wearer's back side is the back side. Furthermore, in the unfolded and extended state shown in Figure 2, diaper 1 has three mutually orthogonal directions: a longitudinal direction, a horizontal direction, and a thickness direction (the direction that penetrates the paper in Figure 2). The longitudinal direction is along the aforementioned vertical direction. One side of the longitudinal direction corresponds to the abdominal side (front side), and the other side corresponds to the back side (back side). Furthermore, as shown in Figure 3, diaper 1 has a thickness direction in which the materials are layered, and in the thickness direction, the side that comes into contact with the wearer is the skin side, and the opposite side is the non-skin side.

[0053] Diaper 1 comprises an absorbent body 10 and an outer casing 18. The outer casing 18 has a pair of waist sections 20 and 30 and a crotch section 40 located between the wearer's legs. The outer casing 18 is attached to the non-skin side of the absorbent body 10 with an adhesive or the like. Of the pair of waist sections 20 and 30, the one located on the wearer's ventral (front) side is also called the ventral waist section 20, and the one located on the dorsal (rear) side is also called the dorsal waist section 30. The ventral waist section 20 and the dorsal waist section 30 are joined on both sides in the left-right direction by a pair of side joints SS. Examples of joining methods using the side joints SS include heat welding, ultrasonic welding, and joining with adhesive.

[0054] As shown in Figure 3, the absorbent body 10 includes an absorbent core (absorbent material) 11, a liquid-permeable top sheet 12 positioned on the skin side of the absorbent core 11, a liquid-impermeable back sheet 13 positioned on the non-skin side of the absorbent core 11, and an outer sheet 14. The absorbent core 11 can be any material that absorbs and retains excretory fluid, and examples include liquid-absorbent materials such as pulp fibers or superabsorbent polymers (SAP) molded into a predetermined shape. The absorbent core 11 may also be covered with a liquid-permeable sheet such as tissue paper or nonwoven fabric. The top sheet 12 is formed from a nonwoven fabric such as air-through nonwoven fabric or spunbond nonwoven fabric. The back sheet 13 is a liquid-impermeable and breathable film such as polyethylene or polypropylene. The outer sheet 14 is formed from a nonwoven fabric equivalent to that of the top sheet 12.

[0055] As shown in Figure 2, multiple leg-circumference elastic members 15 (e.g., elastic threads) that expand and contract along the longitudinal direction of the absorbent body 10 are provided on both sides of the absorbent body 10 in the left-right direction. Furthermore, a leak-proof wall portion that can stand upright on the skin side may be provided by, for example, providing an elastic member that expands and contracts in the longitudinal direction inward from the leg-circumference elastic members 15 in the left-right direction.

[0056] As shown in Figures 2 and 3, the outer casing 18 has an inner layer sheet 21, a ventral outer layer sheet 22 (outer layer sheet), and a dorsal outer layer sheet 32 ​​(outer layer sheet).

[0057] The inner layer sheet 21 is positioned from the ventral waist area 20 through the crotch area 40 to the dorsal waist area 30 (Figure 3). The width (length in the left-right direction) of the inner layer sheet 21 in the ventral waist area 20 and the dorsal waist area 30 is greater than the width (length in the left-right direction) of the inner layer sheet 21 in the crotch area 40 (Figure 2). As the inner layer sheet 21, air-through nonwoven fabric, spunbond nonwoven fabric, SMS nonwoven fabric (spunbond-meltblown-spunbond nonwoven fabric), waterproof film, etc. can be used.

[0058] As shown in Figures 2 and 3, the ventral outer layer sheet 22 is provided on the non-skin side of the inner layer sheet 21, and the ventral outer layer sheet 22 and the inner layer sheet 21 constitute the ventral torso portion 20. The outer end (upper end) of the ventral outer layer sheet 22 in the longitudinal direction is folded back towards the skin side. This folded portion 22r of the ventral outer layer sheet 22 encloses one end (outer end) of the inner layer sheet 21 in the longitudinal direction. Note that the outer end (upper end) of the ventral outer layer sheet 22 in the longitudinal direction may not be folded back.

[0059] Similarly, as shown in Figures 2 and 3, the back outer layer sheet 32 ​​is provided on the non-skin side of the inner layer sheet 21, and the back outer layer sheet 32 ​​and the inner layer sheet 21 constitute the back waist portion 30. The outer end (upper end) of the back outer layer sheet 32 ​​in the longitudinal direction is folded back towards the skin side. This folded portion 32r of the back outer layer sheet 32 ​​encloses the other end (outer end) of the inner layer sheet 21 in the longitudinal direction. Note that the outer end (upper end) of the back outer layer sheet 32 ​​in the longitudinal direction may not be folded back.

[0060] As the ventral outer layer sheet 22 and the dorsal outer layer sheet 32, air-through nonwoven fabric, spunbond nonwoven fabric, SMS nonwoven fabric (spunbond-meltblown-spunbond nonwoven fabric), etc., can be used.

[0061] The ventral waist section 20 and the dorsal waist section 30 each have waist elastic members 23 and 33 that are expandable and contractible in the left-right direction. The multiple waist elastic members 23 and 33 are arranged with vertical spacing between the inner layer sheet 21 and the ventral outer layer sheet 22, and between the inner layer sheet 21 and the dorsal outer layer sheet 32, and are fixed in an expanded state in the left-right direction (see Figures 2 and 3). Therefore, the ventral waist section 20 and the dorsal waist section 30 expand and contract in the left-right direction to fit the wearer's waist. Examples of waist elastic members 23 and 33 include thread-like elastic members such as elastic threads, and elongated stretchable sheets.

[0062] In this embodiment, a rear leg elastic member 34 is provided between the inner layer sheet 21 and the rear outer layer sheet 32 ​​in the dorsal body portion 30. The rear leg elastic member 34 may be, for example, a plurality of elastic threads or a stretchable strip-shaped elastic sheet. The rear leg elastic member 34 is joined and fixed in an extended state with an adhesive such as a hot melt adhesive.

[0063] Furthermore, in this embodiment, sheet portions 25 and 35 that easily absorb the wearer's sweat are provided in predetermined areas of the ventral waist portion 20 and the dorsal waist portion 30 that are closest to the skin (shaded areas in Figure 2). The sheet portions 25 and 35 are positioned closer to the skin than the absorbent body 10 (absorbent core 11), and are shorter in the vertical direction than the inner layer sheet 21, the ventral and dorsal outer layer sheets 22 and 32, etc., and are strip-shaped sheet members positioned to cover the longitudinal ends of the absorbent body 10. Details of the sheet portions 25 and 35 will be described later.

[0064] The basic configuration of diaper 1 has been described above, but the configuration of diaper 1 described above is just one example and is not limited thereto. For example, in this embodiment of diaper 1, the outer body 18 has three parts: an abdominal waist portion 20, a dorsal waist portion 30, and a crotch portion 40 connecting them, but it is not limited to this. For example, the abdominal waist portion 20 and the dorsal waist portion 30 may be made of separate members, and the non-skin side of the absorbent body 10 may be exposed in the crotch portion, or the outer body may be made of a single continuous member extending from the abdominal waist portion 20 to the dorsal waist portion 30.

[0065] <Regarding Sheet Sections 25 and 35> The specific configurations of sheet sections 25 and 35 according to this embodiment will be described below. In this embodiment, sheet section 25 provided on the ventral girth section 20 and sheet section 35 provided on the dorsal girth section 30 have substantially the same configuration. Therefore, in the following description, only sheet section 25 will be described as a representative of both sheet section 25 and sheet section 35, where common elements are included. For sheet section 35, specific descriptions will be omitted, with reference numerals for members etc. corresponding to sheet section 25 indicated in parentheses as needed.

[0066] Figure 4 is a schematic cross-sectional view of the sheet portion 25. Figure 5A is an enlarged view of the sheet portion 25 as seen from the skin side. Figure 5B is an enlarged schematic view of a part of Figure 5A. As described above, in this embodiment, the sheet portion 25 constitutes a part of the surface of the abdominal torso portion 20 that comes into contact with the wearer's skin (see Figure 3). As shown in Figure 4, the sheet portion 25 has a skin-side layer 25a that is positioned to come into contact with the wearer's skin, and a non-skin-side layer 25b that is located on the non-skin side in the thickness direction of the skin-side layer 25a.

[0067] The skin-side layer 25a is a nonwoven fabric layer with a base fiber made of non-heat-fusible fibers such as cotton fibers. Cotton fibers are soft, have a rounded fiber shape, and are highly absorbent. Therefore, by using cotton fibers as the base fiber of the skin-side layer 25a that comes into contact with the wearer's skin, it is possible to provide a comfortable feel against the wearer's skin and reduce irritation to the wearer's skin during wear. The term "base fiber" as used above means a material that accounts for more than 50% of the mass (weight %) of each layer (skin-side layer 25a, non-skin-side layer 25b).

[0068] As the base fibers for the non-skin-facing layer 25b, heat-fusible fibers such as polyester fibers, polypropylene fibers, polyethylene fibers, and polyurethane fibers, or composite fibers thereof, can be used. In the following, the base fibers of the skin-facing layer 25a will also be referred to as "skin-facing fibers," and the base fibers of the non-skin-facing layer 25b will also be referred to as "non-skin-facing fibers." Furthermore, the skin-facing layer 25a will also be referred to as "nonwoven fabric layer 25a," and the non-skin-facing layer 25b will also be referred to as "other layer 25b."

[0069] Furthermore, while the aforementioned fibers may be either those with a hydrophilic treatment applied to their surface or those without, it is preferable that at least the fiber on the skin side has hydrophilic properties.

[0070] Furthermore, in the sheet portion 25 (sheet member) of this embodiment, the skin-side fibers (cotton fibers) 25as, which are the base fibers of the skin-side layer 25a, have portions that are entangled with the non-skin-side fibers 25bs, which are the base fibers of the non-skin-side layer 25b (see Figure 4). As a method for integrating the skin-side layer 25a and the non-skin-side layer 25b by entanglement, a known water flow entanglement method, such as a water jet, can be used.

[0071] Furthermore, the skin-side layer 25a has a predetermined basis weight portion 25aP with skin-side fibers 25as of a predetermined basis weight, and a low basis weight portion 25aL in which the basis weight of the skin-side fibers 25as is lower than that of the predetermined basis weight portion 25aP. As shown in Figures 4 and 5, when the sheet portion 25 (diaper 1) is viewed in the thickness direction, there is a portion where the predetermined basis weight portion 25aP and the non-skin-side layer 25b overlap, and a portion where the low basis weight portion 25aL and the non-skin-side layer 25b overlap. By having a portion where the predetermined basis weight portion 25aP and the non-skin-side layer 25b of the skin-side layer 25a overlap, when worn, the predetermined basis weight portion 25aP of the sheet portion 25 comes into contact with the wearer's skin, improving the water absorption and feel of the sheet portion 25 (diaper 1) when worn. On the other hand, having an overlapping portion between the low basis weight section 25aL and the non-skin layer 25b allows the overlapping portion between the predetermined basis weight section 25aP and the non-skin layer 25b to absorb moisture such as sweat from the wearer's skin when worn. This facilitates evaporation of the moisture absorbed by the predetermined basis weight section 25aP from the low basis weight section 25aL, where the basis weight of the skin-side fibers 25as is lower, and also facilitates the movement of moisture from the low basis weight section 25aL to the non-skin layer 25b.

[0072] The "low basis weight portion 25aL" is any portion where the basis weight of the skin-side fibers 25as is lower than that of the predetermined basis weight portion 25aP, and includes cases where skin-side fibers 25as are provided in the low basis weight portion 25aL and cases where skin-side fibers 25as are not provided. In either case, it is preferable that the low basis weight portion 25aL is a portion that is recessed on the non-skin side than the predetermined basis weight portion 25aP (see Figure 4). Because the low basis weight portion 25aL is recessed on the non-skin side than the predetermined basis weight portion 25aP, when worn, the predetermined basis weight portion 25aP of the skin-side layer 25a of the sheet portion 25 is a portion that is more likely to come into contact with the wearer's skin, improving the feel against the wearer's skin, while the low basis weight portion 25aL is a portion that is less likely to come into contact with the wearer's skin. Therefore, moisture such as sweat can be easily transferred to the non-skin layer 25b via the low basis weight portion 25aL where the skin-side fibers 25as are less numerous. Even when the skin-side layer 25a absorbs moisture such as sweat during wear, the portion of the skin-side layer 25a that comes into contact with the wearer's skin is reduced, thereby reducing the risk of the wearer feeling sticky on their skin even when the skin-side fibers 25as of the skin-side layer 25a absorb moisture.

[0073] In this embodiment, the low basis weight portion 25aL is a portion where there are almost no skin-side fibers 25as, and the basis weight of the skin-side fibers 25as is 0 (zero). Simply put, it is a portion where the skin-side layer 25a is missing in the thickness direction. Therefore, when the sheet portion 25 is viewed from the skin side, the non-skin-side layer 25b (non-skin-side fibers 25bs) can be seen through the low basis weight portion 25aL (see Figure 5A). Note that since the skin-side fibers 25as are soft fibers with some fluidity, a portion where the basis weight of the skin-side fibers 25as is 0 (zero) does not mean that there are absolutely no skin-side fibers 25as, but rather that there may be a portion in the low basis weight portion 25aL where a few skin-side fibers 25as are provided.

[0074] <Details of the composition of the skin-side fibers> As described above, in the sheet portion 25 of this embodiment, the skin-side layer 25a (nonwoven fabric layer 25a) is composed of non-heat-fusible fibers such as cotton fibers as the base fibers. In this embodiment, the non-heat-fusible fibers that make up the nonwoven fabric layer 25a have a shorter average fiber length and less variation in fiber length compared to conventional general non-heat-fusible fibers. The detailed composition of the base fibers (skin-side fibers 25as) of the nonwoven fabric layer 25a will be described below.

[0075] First, we will briefly explain the conventional method for manufacturing cotton fibers, which are a common non-heat-fusible fiber. When manufacturing cotton fibers, first, raw cotton is obtained. Next, foreign matter such as seeds, leaves, and stems contained in the raw cotton is removed, and degreasing and bleaching are performed to produce bleached cotton. Then, this bleached cotton is entangled with a water flow on a nonwoven fabric base to produce cotton material.

[0076] Normally, when manufacturing bleached cotton, a carding process is performed using a carding machine (not shown) equipped with a rotating body having multiple thorns on its circumferential surface to scrape and loosen the compressed raw cotton fibers while removing foreign matter. At this time, the short fiber scraps scraped off by the carding machine are also called "combed noil". In the sheet portion 25 of this embodiment, this combed noil can be used as the base fiber of the nonwoven fabric layer 25a. Of course, the nonwoven fabric layer 25a may also be composed of non-heat-fusible fibers other than combed noil.

[0077] Figure 6A shows data measuring the distribution of fiber lengths of skin-side fibers constituting the nonwoven fabric layer 25a (skin-side layer 25a) in this embodiment, and Figure 6B shows data measuring the distribution of fiber lengths of skin-side fibers in the sheet member of the comparative example. Furthermore, Figure 7A is a graph showing the fiber length distribution of Figure 6A (this embodiment), and Figure 7B is a graph showing the fiber length distribution of Figure 6B (comparative example). The sheet member of the comparative example has a skin-side layer and a non-skin-side layer, and is a sheet member (nonwoven fabric) that uses conventional non-heat-fusible fibers (cotton fibers, etc.) as the base fibers (skin-side fibers) of the skin-side layer. In other words, the sheet member of the comparative example differs from the sheet portion 25 (sheet member) of this embodiment in that it uses ordinary non-heat-fusible fibers (cotton fibers, etc.), which are different from combed noil, as the base fibers constituting the skin-side layer. Furthermore, the fiber length distribution data shown in Figures 6A and 6B can be obtained by measuring the fiber length based on the method using a fiber sorter as specified in "JIS L1019:2006 Cotton Fiber Testing Methods," section 7.2.

[0078] As shown in Figures 6 and 7, the average fiber length of the base fibers (non-heat-fusible fibers) constituting the nonwoven fabric layer 25a in the sheet portion 25 of this embodiment was 10.99 mm, and the standard deviation was 4.69. On the other hand, in the sheet member of the comparative example, the average fiber length of the base fibers (non-heat-fusible fibers) constituting the skin-side layer was 14.96 mm, and the standard deviation was 7.66. From this, it can be confirmed that the non-heat-fusible fibers, which are the base fibers of the nonwoven fabric layer 25a in this embodiment, have a shorter average fiber length and less variation in distribution than the non-heat-fusible fibers, which are the base fibers of the nonwoven fabric layer of the comparative example.

[0079] Normally, variations in the density of the fibers constituting a sheet member can lead to a partial decrease in the amount of moisture absorbed by the sheet member, uneven thickness, and partial increases or decreases in rigidity. In contrast, in this embodiment, the variation in the fiber length of the non-heat-fusible fibers constituting the nonwoven fabric layer 25a (skin-side layer 25a) in the sheet portion 25 (sheet member) is smaller compared to the variation in the fiber length of non-heat-fusible fibers in conventional sheet members. Referring to the data in Figure 6, specifically, if the standard deviation of the fiber length of the non-heat-fusible fibers is around 4.69, it becomes easier to reduce the risk of partial decreases in the amount of moisture absorbed by the sheet member, uneven thickness of the sheet member, and changes in the partial rigidity of the sheet member compared to conventional designs. Even if the magnitude of the standard deviation fluctuates by about ±10% due to errors during fiber length measurement, if the standard deviation of the fiber length of the non-heat-fusible fibers is 5.5 or less, the variation in fiber length will be smaller than when the standard deviation of the fiber length of the non-heat-fusible fibers is greater than 5.5, making it easier to suppress a decrease in absorption capacity, etc. In the nonwoven fabric layer 25a of this embodiment, the average fiber length of the fibers is shortened to reduce variation while preventing the fiber length from becoming excessively short. Specifically, by having an average fiber length of 5 mm or more for the non-heat-fusible fibers, the risk of the non-heat-fusible fibers falling off the sheet member can be reduced compared to when the average fiber length of the non-heat-fusible fibers is shorter than 5 mm. In addition, because the sheet member has non-heat-fusible fibers, even when heat is applied to the sheet member, it is less likely to form partially hardened areas due to fusion compared to when there are no non-heat-fusible fibers. As a result, it is easier to reduce the risk of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and changes in the partial rigidity of the sheet member.

[0080] According to "Hibiki, Teru. Characteristics of Cotton Fibers from a Practical Perspective. Journal of the Textile Institute. 2006, Vol. 62, No. 7, P-191," fiber length can be classified into the following five stages: short fibers (less than 20.6 mm), medium fibers (20.6 to 25.4 mm), medium-long fibers (26.2 to 27.8 mm), long fibers (28.6 to 34.1 mm), and extra-long fibers (34.9 mm or more).

[0081] In the comparative example sheet member, the proportion (by weight) of fibers with a fiber length of less than 20.6 mm, which are classified as short fibers, among the multiple non-heat-fusible fibers constituting the nonwoven fabric layer is approximately 76.3% (see Figure 6B). In contrast, in this embodiment, the proportion (by weight) of fibers with a fiber length of less than 20.6 mm, which are classified as short fibers, among the multiple non-heat-fusible fibers constituting the nonwoven fabric layer 25a of the sheet portion 25 is approximately 94.4% (see Figure 6A). In other words, in this embodiment, short fibers with an average fiber length of less than 20.6 mm account for at least 90% by weight of the multiple non-heat-fusible fibers. This also shows that the nonwoven fabric layer 25a of this embodiment contains more short fibers than conventional nonwoven fabrics. Therefore, in the sheet portion 25 (sheet member) of this embodiment, it is possible to make the density of non-heat-fusible fibers in the sheet member more uniform than when non-heat-fusible fibers with a fiber length of 20.6 mm or more account for more than 10% by weight of the multiple non-heat-fusible fibers. This makes it easier to reduce the risk of partial reductions in the amount of moisture absorbed by the sheet material, unevenness in the thickness of the sheet material, and partial changes in the rigidity of the sheet material.

[0082] Furthermore, focusing on non-heat-fusible fibers with a fiber length of 12 mm or less, in the comparative example sheet member, the proportion (by weight) of fibers with a fiber length of 12 mm or less is 45.6%, which is less than 50% of the total weight (see Figure 6B). In contrast, in the sheet portion 25 of this embodiment, the proportion (by weight) of fibers with a fiber length of 12 mm or less is 75% or more, which is significantly more than 50% (see Figure 6A). Thus, in the sheet portion 25 (sheet member), non-heat-fusible fibers with a fiber length of 12 mm or less account for 50% by weight or more of the multiple non-heat-fusible fibers, making it easier to make the density of non-heat-fusible fibers uniform compared to conventional sheet members where non-heat-fusible fibers with a fiber length of 12 mm or less account for less than 50% by weight. Therefore, it is possible to reduce the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member.

[0083] Furthermore, while the longest non-heat-fusible fiber in the comparative example's sheet member was 36 mm, the longest non-heat-fusible fiber in the sheet portion 25 (sheet member) of this embodiment was 34 mm (see Figures 6A and 6B). In other words, the sheet portion 25 (sheet member) of this embodiment did not have any non-heat-fusible fibers longer than 35 mm. Thus, with the sheet portion 25 (sheet member) of this embodiment, it is easier to make the density of non-heat-fusible fibers in the sheet member uniform compared to the case where there are multiple non-heat-fusible fibers with a fiber length of 35 mm or more. Therefore, it is easier to reduce the risk of partial reductions in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member.

[0084] Furthermore, as explained in Figure 4, the sheet portion 25 of this embodiment is formed by entangling multiple fibers with water flow. In other words, the sheet portion 25 (sheet member) is formed by entangling the fibers with each other without using an adhesive. With such a sheet member, it is possible to suppress the hardening of the sheet member caused by the presence of an adhesive, while also reducing the risk that the adhesive will hinder the absorption of moisture.

[0085] Furthermore, according to the sheet portion 25 (sheet member) of this embodiment, the intertwining of the fibers makes it easier to form numerous voids between the fibers (see Figure 4), thereby reducing the risk of the sheet member becoming hard and further reducing the risk of moisture absorption being hindered.

[0086] Furthermore, the sheet portion 25 (sheet member) of this embodiment is formed without non-heat-fusible fibers fusing together. With such a sheet member, the risk of the sheet member becoming hard is reduced because there are no portions where non-heat-fusible fibers are fused together, while also reducing the risk of moisture absorption being hindered by portions where non-heat-fusible fibers are fused together.

[0087] Furthermore, the nonwoven fabric layer 25a (skin-facing layer 25a) of the sheet portion 25 contains substances different from cotton fibers. While it has been explained that the nonwoven fabric layer 25a contains combed oil removed during the carding process, foreign matter such as seed hulls, leaves, and stems removed from the raw cotton along with the combed oil may also be mixed into the nonwoven fabric layer 25a. The size of these substances is approximately 1 mm. ２ In some cases, the above is the case. In this case, when viewed in the thickness direction, there is 1 mm on the surface of the sheet portion 25 (sheet member). ２ Multiple scattered objects of a certain size become more easily visible. Users can more easily recognize the presence of the sheet material by visually identifying the presence of substances such as seed husks and leaves in the non-heat-fused fibers (cotton fibers). Furthermore, substances such as seed husks removed from raw cotton during the carding process may retain their brownish color even after bleaching, in which case these substances become even more visible.

[0088] Furthermore, because the substance contained in the sheet portion 25 (sheet member) is at least one of leaves, seed husks, or stems, it is easier to give users who see the substance the impression that the sheet member is made of natural materials. This makes it easier to evoke an image of being gentle on the skin and safe for the environment.

[0089] Furthermore, it is preferable that the basis weight of the seed husks and other materials in the entire sheet portion 25 (sheet member) is smaller than the basis weight of the non-heat-fusible fibers (cotton fibers). If the basis weight of the seed husks and other materials is larger than that of the cotton fibers, the proportion of foreign matter contained in the sheet member will be larger and more noticeable, which may cause users to worry that the amount of moisture absorbed by the cotton fibers will decrease. In contrast, if the basis weight of the seed husks and other materials is smaller than that of the non-heat-fusible fibers (cotton fibers), it is possible to give users the impression that the sheet member is made of natural materials while reducing the risk of reduced moisture absorption by the cotton fibers.

[0090] Furthermore, when the sheet portion 25 (sheet member) is divided into three equal parts in the thickness direction, it is preferable that non-heat-fusible fibers (cotton fibers) account for 90% or more by weight of the fibers constituting the sheet portion 25 in at least one outer surface layer. For example, when the sheet portion 25 (sheet member) is divided into three equal parts in the thickness direction as shown in Figure 4, the layers are designated as the first layer TA1, the second layer TA2, and the third layer TA3 in order from the skin side to the non-skin side. In this case, the first layer TA1 is a layer that overlaps with the skin side layer 25a, and the third layer TA3 is a layer that overlaps with the non-skin side layer 25b. In this embodiment, the first layer TA1 facing the outside (skin side) in the thickness direction is a nonwoven fabric (nonwoven fabric layer 25a) containing non-heat-fusible fibers (cotton fibers), and 90% or more by weight of the fibers constituting the nonwoven fabric are non-heat-fusible fibers (cotton fibers).

[0091] With such a sheet portion 25 (sheet member), it becomes easier to reduce the risk of partial reduction in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial changes in the rigidity of the sheet member on at least one surface in the thickness direction (first layer TA1 in Figure 4). In addition, the sheet portion 25 (sheet member) may be configured such that a layer of heat-fusible fibers is arranged on the skin side in the thickness direction, and a layer of non-heat-fusible fibers (cotton fibers) is arranged on the non-skin side in the thickness direction. In this case, 90% or more by weight of the fibers constituting the third layer TA3 facing the outside (non-skin side) in the thickness direction will be non-heat-fusible fibers (cotton fibers), and it will be possible to obtain the same effects as in the above case depending on the application of the sheet member.

[0092] Furthermore, the sheet portion 25 (sheet member) of this embodiment has a skin-side layer 25a (nonwoven fabric layer 25a) which is a layer that can come into contact with the wearer's skin when wearing the diaper 1, and a non-skin-side layer 25b (other layer 25b) which is provided on the non-skin side of the skin-side layer 25a. More than 90% by weight of the fibers constituting the skin-side layer 25a (nonwoven fabric layer 25a) are multiple non-heat-fusible fibers (cotton fibers), while more than 90% by weight of the fibers constituting the non-skin-side layer 25b (other layer 25b) are multiple heat-fusible fibers.

[0093] Specifically, the skin-facing side of the sheet portion 25 (sheet member) is provided with a nonwoven fabric layer 25a mainly composed of cotton fibers with good liquid absorption, and the non-skin-facing side of the sheet portion 25 (sheet member) is provided with another layer 25b mainly composed of heat-fusible fibers with good liquid evaporation properties. With this configuration, the nonwoven fabric layer 25a on the skin-facing side of the sheet portion 25 (sheet member) can easily absorb moisture such as sweat from the wearer, and the absorbed moisture can be moved to the other layer 25b on the non-skin-facing side and evaporated easily. Therefore, it is possible to suppress stuffiness and discomfort to the wearer when the skin-facing side of the sheet portion 25 comes into contact with the wearer's skin.

[0094] In this configuration, it is preferable that the average fiber length of the non-heat-fusible fibers (cotton fibers) constituting the skin-side layer 25a (nonwoven fabric layer 25a) is shorter than the average fiber length of the heat-fusible fibers constituting the non-skin-side layer 25b (other layers 25b), and that the non-heat-fusible fibers (cotton fibers) and heat-fusible fibers are intertwined with each other. With such a configuration, in the sheet portion 25 (sheet member), the non-heat-fusible fibers (cotton fibers) with shorter average fiber lengths are covered from the non-skin side by the heat-fusible fibers with longer average fiber lengths. Therefore, it is easier to suppress the non-heat-fusible fibers (cotton fibers) from falling off to the outside (non-skin side) of the sheet member when wearing the diaper 1, etc. Furthermore, since the shedding of non-heat-fusible fibers is suppressed and the fiber density in the skin-side layer 25a of the sheet member is more easily maintained in a uniform state, it is easier to reduce the risk of a decrease in water absorption, uneven thickness, changes in rigidity, etc.

[0095] Furthermore, the skin-facing layer 25a (nonwoven fabric layer 25a) contains substances (foreign matter) different from the non-heat-fused fibers (cotton fibers) such as seed husks, leaves, and stems mentioned above, whereas the non-skin-facing layer 25b (other layers 25b) does not contain such substances. In other words, the non-skin-facing layer 25b (other layers 25b) is 1 mm thick when viewed in the thickness direction. ２It does not contain any material of a size greater than the specified size. In such a sheet material, foreign matter is easily visible on one side in the thickness direction (in this case, the skin side), while it is not easily visible on the other side in the thickness direction (the non-skin side). Therefore, the user can easily recognize at a glance which side in the thickness direction has a layer of nonwoven fabric made of non-heat-fusible fibers.

[0096] Furthermore, in the sheet portion 25 (sheet member), it is preferable that the value obtained by dividing the total weight of non-heat-fusible fibers (cotton fibers) by the weight of the sheet member is smaller than the value obtained by dividing the total weight of heat-fusible fibers by the weight of the sheet member. In other words, it is preferable that the mass percentage of non-heat-fusible fibers (cotton fibers) in the sheet portion 25 (sheet member) is smaller than the mass percentage of heat-fusible fibers in the sheet portion 25 (sheet member). In such a sheet member, moisture can be easily absorbed by the non-heat-fusible fibers (cotton fibers) with a small mass percentage, while the absorbed moisture can be easily evaporated to the atmosphere from the heat-fusible fibers with a large mass percentage. Therefore, moisture evaporation can be improved compared to when the value obtained by dividing the total weight of cotton fibers by the weight of the sheet member is larger than the value obtained by dividing the total weight of heat-fusible fibers by the weight of the sheet member.

[0097] Furthermore, when the sheet portion 25 (sheet member) is in its natural state, it is preferable that the thickness of the skin-side layer 25a (nonwoven fabric layer 25a) is greater than the thickness of the non-skin-side layer 25b (other layers 25b). In Figure 4, the thickness of the skin-side layer 25a (nonwoven fabric layer 25a) is greater than the thickness of the non-skin-side layer 25b (other layers 25b). With such a configuration, the feel against the skin can be made softer than when the thickness of the nonwoven fabric layer 25a on the skin-side surface that comes into contact with the wearer's skin is thinner than the thickness of the other layers 25b. In addition, it is possible to make it easier for the cotton fibers on the skin side to absorb moisture while improving moisture evaporation.

[0098] In addition, for measuring the thickness of the nonwoven fabric layer 25a and the other layer 25b, after separating the respective layers, the thickness at a plurality of locations (for example, 10 locations) is measured for the cross-section in the thickness direction of each layer using a microscope or the like, the average value is obtained, and this value is used as the thickness of each layer. Alternatively, a cross-section in the thickness direction of the sheet portion 25 (sheet member) in a natural state may be photographed, and the average values of the thickness of the nonwoven fabric layer 25a and the thickness of the other layer 25b may be calculated by image analysis using a computer.

[0099] In addition, in the present embodiment, the basis weight of the sheet portion 25 (sheet member) is 30 g / m ２ or less is preferable. Generally, as the basis weight of the sheet member increases, the sheet member tends to become harder. In the present embodiment, by setting the basis weight of the sheet portion 25 (sheet member) to 30 g / m ２ or less, when the basis weight of the sheet member is 30 g / m ２ the sheet member can be made softer than when it is larger than the above value.

[0100] In addition, in the sheet portion 25 (sheet member), the standard deviation of the fiber length of the heat-fusible fibers may be smaller than the standard deviation of the fiber length of the non-heat-fusible fibers (cotton fibers). With such a sheet member, variation in the density of cotton fibers in the skin-side layer 25a (nonwoven fabric layer 25a) can be reduced, and variation in the density of heat-fusible fibers in the non-skin-side layer 25b (other layer 25b) can be further reduced. In this case, it is possible to easily reduce the risk that partial reduction in the amount of absorbed moisture, uneven thickness of the sheet member, and partial change in rigidity of the sheet member occur over the entire sheet member.

[0101] Furthermore, as explained in Figure 4, the skin-side layer 25a (nonwoven fabric layer 25a) of the sheet portion 25 (sheet member) is provided with a predetermined basis weight portion 25aP and a low basis weight portion 25aL, and when viewed in the thickness direction, both have portions that overlap with the non-skin-side layer 25b (other layers 25b). Then, as shown in Figures 5A and 5B, in the vertical direction (up and down direction of the diaper 1), the predetermined basis weight portion 25aP and the low basis weight portion 25aL are arranged alternately, and in the horizontal direction (left and right direction of the diaper 1), the predetermined basis weight portion 25aP and the low basis weight portion 25aL are arranged alternately. As a result, when worn, the portion where the predetermined basis weight portion 25aP and the non-skin layer 25b overlap in the thickness direction absorbs moisture such as sweat from the wearer's skin. This facilitates evaporation of the moisture absorbed by the predetermined basis weight portion 25aP from the low basis weight portion 25aL of the skin-side fibers 25as, and also facilitates the movement of moisture from the low basis weight portion 25aL to the non-skin layer 25b. Therefore, the risk of excessive moisture retention in the skin-side layer 25a is reduced, thereby reducing the risk of the diaper 1 becoming stuffy or causing adverse effects such as skin irritation. Furthermore, because the predetermined basis weight portion 25aP and the low basis weight portion 25aL are arranged alternately in the vertical direction, and the predetermined basis weight portion 25aP and the low basis weight portion 25aL are arranged alternately in the horizontal direction, discomfort and adverse effects on the wearer's skin from the diaper 1 can be reduced over a wide area of ​​the sheet portion 25.

[0102] Furthermore, it is preferable that the length of the low-basis-weight section 25aL in the vertical direction is shorter than the average fiber length of the non-heat-fusible fibers (cotton fibers), and the length of the low-basis-weight section 25aL in the horizontal direction is shorter than the average fiber length of the non-heat-fusible fibers (cotton fibers). In the sheet section 25 (sheet member) of this embodiment, the wider the low-basis-weight section 25aL, the more likely the non-heat-fusible fibers (cotton fibers) are to fall off the sheet member. Therefore, by making the length of the low-basis-weight section 25aL in the vertical direction and the length in the horizontal direction shorter than the average fiber length of the non-heat-fusible fibers (cotton fibers), the risk of cotton fibers falling off the sheet member can be reduced.

[0103] <Regarding the arrangement of the sheet portion 25 in diaper 1> Figures 8 to 11 show modified examples of the arrangement of the sheet member of the present invention. In each modified example, the sheet portion 25 is a sheet member having the above-described features.

[0104] (Modification 1) Figures 8A and 8B illustrate Modification 1 of the arrangement of the sheet portion 25 of the present invention. In Modification 1, no separate sheet member is provided as the sheet portion 25, and the folded portion 22r (32r) of the ventral outer layer sheet 22 (dorsal outer layer sheet 32) is made into the sheet portion 25 (35). In this Modification 1, at least the portion of the ventral outer layer sheet 22 (dorsal outer layer sheet 32) that becomes the sheet portion 25 (35) has a skin-side layer (cotton layer) 25a on the skin side and a non-skin-side layer 25b on the non-skin side in the thickness direction of the skin-side layer 25a. Furthermore, the sheet portion 25 (35), which is part of the ventral outer layer sheet 22 (dorsal outer layer sheet 32), and the inner layer sheet 21 (adjacent sheet member) adjacent to the sheet portion 25 (35) from the non-skin side in the thickness direction, are joined by welding or adhesive to a joint portion (not shown), and the sheet portion 25 (35) and the inner layer sheet 21 (adjacent sheet member) are not joined by welding or adhesive to a joint portion (not shown). With this configuration, the sheet portion 25 can obtain the same effects as those of the embodiment described above.

[0105] In this modified example, the folded portion 22r (32r) of the sheet portion 25 (35) is a tightly constricting area on the ventral waist portion 20 (dorsal waist portion 30). Having a skin-side layer 25a on the skin-contacting surface of such an area allows the wearer to better feel the softness of the skin-side fibers 25as, such as cotton fibers. Furthermore, the non-jointed portion allows it to easily follow the movement of the waist, reducing friction with the skin and suppressing pilling of the skin-side fibers 25as, such as cotton fibers. In Modified Example 1, the sheet portion 25 (35) is replaced with a folded portion 22r (32r), but the invention is not limited to this. Whether or not the diaper 1 has a folded portion 22r (32r), the sheet portion 25 (35) may be positioned as shown in Figure 8.

[0106] (Modification 2) Figure 9 is a diagram illustrating modification 2 of the arrangement of the sheet portion 25 of the present invention. In modification 2 shown in Figure 9, the sheet portion 25 (35) is not provided to both ends in the left-right direction of the ventral waist portion 20 (dorsal waist portion 30), but is provided in the central part in the left-right direction of the ventral waist portion 20 (dorsal waist portion 30), and straddles the upper end 10e of the absorbent body 10 in the vertical direction. Since the upper end 10e of the absorbent body 10 is a part where the irregularities are relatively large, by arranging the sheet portion 25 (35) so that at least the entire upper end 10e is covered, friction to the skin when worn can be suppressed and irritation to the skin can be reduced.

[0107] (Modification 3) Figure 10 is a diagram illustrating modification 3 of the arrangement of the sheet portion 25 of the present invention. In modification 3 shown in Figure 10, a sheet member which will be the sheet portion 25 (35) is provided between the absorbent main body 10 and the inner layer sheet 21. The sheet member which will be the sheet portion 25 is provided in the ventral waist portion 20 between one end of the pair of side joints SS in the left-right direction and the other end, and in the region from the upper end to the lower end in the vertical direction of the pair of side joints SS. In the dorsal waist portion 30, the sheet member which will be the sheet portion 35 is provided between one end of the pair of side joints SS in the left-right direction and the other end, and in the region from the upper end to near the lower end in the vertical direction of the pair of side joints SS. With this configuration, the skin-side layer 25a is present on most of the skin-contact surface in the area of ​​the ventral waist portion 20 (dorsal waist portion 30) other than the area where the absorbent main body 10 is located, improving the feel against the skin. Furthermore, because the sheet portion 25 (35) and the inner layer sheet 21 have non-jointed portions that are not joined by welding or adhesive, the sheet portion 25 (35) can easily follow the movement of the wearer's waist, reducing friction with the skin. This suppresses fluffing of the skin-side fibers 25as, such as cotton fibers, even if the proportion of the skin-side layer 25a in contact with the skin is large. In addition, in the waist portions 20 and 30, the sheet portions 25 and 35 may be placed as the sheets on the skin-side of the waist portions 20 and 30 instead of the inner layer sheets 21 and 31.

[0108] Furthermore, if the non-skin-facing fiber 25bs is a thermoplastic fiber, the diaper 1 may have an adjacent member provided at a position overlapping with the sheet portion 25 when viewed in the thickness direction, and the diaper 1 may have a welded joint where the sheet portion 25 and the adjacent member are welded together in the thickness direction, and the diaper 1 may be configured such that at least a part of the welded joint overlaps with the portion where the low basis weight portion 25aL and the non-skin-facing layer 25b overlap when viewed in the thickness direction. For example, in the modified examples 1 to 3 shown in Figures 8 to 10, when the inner layer sheet 21 (or ventral outer layer sheet 22) at a position overlapping with the sheet portion 25 of the ventral waist portion 20 when viewed in the thickness direction is the adjacent member, the sheet portion 25 and the inner layer sheet 21 (or ventral outer layer sheet 22) may have a welded joint (not shown) where they are welded together in the thickness direction. In such cases, it is preferable that at least a portion of the welded joint overlaps with the portion where the low basis weight portion 25aL of the sheet portion 25 and the non-skin side layer 25b overlap when viewed in the thickness direction. This reduces the risk of a decrease in the bonding strength of the welded joint that welds the sheet portion 25 and the inner layer sheet 21 (or outer layer sheet 22).

[0109] In the embodiments and modifications 1 to 3 described above, a sheet portion 25 is provided on the ventral waist portion 20 and a sheet portion 35 is provided on the dorsal waist portion 30, but the invention is not limited to this. Each diaper 1 may have a configuration in which the sheet portion 25 is provided only on the ventral waist portion 20 and the sheet portion 35 is not provided on the dorsal waist portion 30, or a configuration in which the sheet portion 35 is provided only on the dorsal waist portion 30 and the sheet portion 25 is not provided on the ventral waist portion 20.

[0110] (Modification 4) Figure 11 is a diagram illustrating modification 4 of the arrangement of the sheet portion 25 of the present invention. In modification 4 shown in Figure 11, the sheet portion 25 is provided as the top sheet 12 of the absorbent body 10. Since the top sheet 12 is the part of the absorbent body 10 that comes into contact with the wearer's skin, providing the sheet portion 25 as the top sheet 12 improves the feel against the skin with the skin-side fibers 25as of the skin-side layer 25a, while reducing discomfort to the wearer's skin and adverse effects on the wearer's skin.

[0111] Furthermore, the modified diaper 1 in Figure 11 (modification 4) may have a compression member having a portion (not shown) that is compressed in the thickness direction. Examples of the compression member include an absorbent core 11. In the diaper 1, a sheet portion 25 (top sheet 12) may be provided on the skin side of the compression member (absorbent core 11), and when viewed in the thickness direction, the portion that overlaps with the compressed portion of the compression member (absorbent core 11) may be in the portion that overlaps with the low basis weight portion 25aL and the non-skin side layer 25b. Generally, the compressed portion is a portion with a high fiber density, and therefore easily absorbs moisture by capillary action. For this reason, having a portion with a high density due to compression in the compression member (absorbent core 11) makes it easier to move moisture from the sheet portion 25 (top sheet 12) to the compression member located on the non-skin side of the sheet portion 25.

[0112] ===Other=== The above embodiments are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention can be modified and improved without departing from its spirit, and it goes without saying that the present invention includes equivalents thereof.

[0113] 1 Diaper (Pants-type disposable diaper, disposable absorbent item), 10 Absorbent body, 10e Upper end, 11 Absorbent core (absorbent material), 12 Top sheet, 13 Back sheet, 14 Outer sheet, 15 Leg circumference elastic member, 18 Outer body, 20 Ventral waist circumference, 20e Upper end, 21 Inner layer sheet, 22 Ventral outer layer sheet, 22r Folded portion, 23 Waist circumference elastic member, 25 Sheet portion (sheet member), 25a Skin-side layer (nonwoven fabric layer), 25aL Low basis weight portion, 25aP Predetermined basis weight portion, 25as Skin-side fibers (cotton fibers, non-heat-fusible fibers), 25b Non-skin-side layer (other layers), 25bs Non-skin-side fibers, 30 Dorsal waist circumference, 32 Dorsal outer layer sheet, 32r Folded section, 33 Elastic member around the torso, 34 Elastic member around the rear legs, 35 Seat section (seat member), 40 Crotch area, SS Side joint (joint)

Claims

1. A sheet member characterized by having a nonwoven fabric layer having a plurality of non-heat-fusible fibers, wherein the average fiber length of the non-heat-fusible fibers is 5 mm or more, and the standard deviation of the fiber lengths of the non-heat-fusible fibers is 5.5 or less.

2. A sheet member according to claim 1, characterized in that, among the plurality of non-heat-fusible fibers, the non-heat-fusible fibers having a fiber length of less than 20.6 mm account for 90% by weight or more of the plurality of non-heat-fusible fibers.

3. A sheet member according to claim 1, characterized in that, among the plurality of non-heat-fusible fibers, the non-heat-fusible fibers having a fiber length of 12 mm or less account for 50% by weight or more of the plurality of non-heat-fusible fibers.

4. A sheet member according to claim 1, characterized in that the plurality of non-heat-fusible fibers do not include any non-heat-fusible fibers having a fiber length of 35 mm or more.

5. A sheet member according to claim 1, characterized in that no adhesive is provided on the sheet member.

6. A sheet member according to claim 5, characterized in that the non-heat-fusible fibers are intertwined with each other.

7. A sheet member according to claim 1, characterized in that it does not have portions in which the non-heat-fusible fibers are fused together.

8. The sheet member according to claim 1, wherein the non-heat-fusible fibers are cotton fibers, and the material is different from the cotton fibers, and the material is 1 mm in thickness when viewed in the thickness direction. ２ A sheet member characterized by having the above size.

9. A sheet member according to claim 8, characterized in that, in the entire sheet member, the basis weight of the substance is smaller than the basis weight of the cotton fibers.

10. A sheet member according to claim 1, characterized in that, in a layer having at least one outer surface when the sheet member is divided into three equal parts in the thickness direction, the non-heat-fusible fibers account for 90% by weight or more of the fibers constituting the sheet member.

11. A sheet member according to claim 1, wherein the nonwoven fabric layer is a layer that can come into contact with the user's skin, and has another layer provided on the non-skin side of the nonwoven fabric layer in the thickness direction, the non-heat-fusible fibers are cotton fibers, 90% by weight or more of the fibers constituting the nonwoven fabric layer are a plurality of cotton fibers, and 90% by weight or more of the fibers constituting the other layer are a plurality of heat-fusible fibers.

12. A sheet member according to claim 11, characterized in that the average fiber length of the cotton fibers is shorter than the average fiber length of the heat-fusible fibers, and the cotton fibers are entangled with the heat-fusible fibers.

13. A sheet member according to claim 11, characterized in that the value obtained by dividing the total weight of the cotton fibers by the weight of the sheet member is smaller than the value obtained by dividing the total weight of the heat-fusible fibers by the weight of the sheet member.

14. A sheet member according to claim 11, characterized in that the thickness of the nonwoven fabric layer is greater than the thickness of the other layers.

15. The sheet member according to claim 11, wherein the sheet member has a basis weight of 30 g / m². ２ A sheet member characterized by the following:

16. A sheet member according to claim 11, characterized in that the standard deviation of the fiber length of the heat-fusible fibers is smaller than the standard deviation of the fiber length of the cotton fibers.

17. A sheet member according to claim 11, having a longitudinal direction and a transverse direction perpendicular to the thickness direction, wherein the nonwoven fabric layer has a predetermined basis weight portion having cotton fibers of a predetermined basis weight and a low basis weight portion having a lower basis weight of cotton fibers than the predetermined basis weight portion, having a portion where the predetermined basis weight portion and the other layer overlap and a portion where the low basis weight portion and the other layer overlap when viewed in the thickness direction, the predetermined basis weight portion and the low basis weight portion are arranged alternately in the longitudinal direction, the predetermined basis weight portion and the low basis weight portion are arranged alternately in the transverse direction, the length of the low basis weight portion in the longitudinal direction is shorter than the average fiber length of the cotton fibers, and the length of the low basis weight portion in the transverse direction is shorter than the average fiber length of the cotton fibers.

18. A disposable absorbent article characterized by comprising a sheet member as described in any one of claims 1 to 17.

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