Sheet member and disposable absorbent article

Abstract

Reduce the risk of partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and partial change in the rigidity of the sheet member. 【Solution means】It has a non-woven fabric layer (25a) having a plurality of non-thermally fused fibers (25as), the average fiber length of the non-thermally fused fibers (25as) is 5 mm or more, and the standard deviation of the fiber length of the non-thermally fused fibers is 5.5 or less.

Description

Technical Field

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

Background Art

[0002] A sheet member used in an absorbent article is a member that comes into contact with the wearer's skin and absorbs excrement, sweat, etc. For example, Patent Document 1 discloses a disposable diaper provided with a sweat-absorbing sheet. In the diaper of Patent Document 1, the sweat-absorbing sheet is provided so as to come into contact with the wearer's torso in order to absorb the wearer's sweat.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a sheet member such as the sweat-absorbing sheet of Patent Document 1, as the density of the fibers constituting the sheet member varies, there is a risk that the amount of moisture absorbed by the sheet member may partially decrease, the thickness may become uneven, the rigidity may become partially high or low.

[0005] The present invention has been made in view of the above problems, and an object thereof is 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 a change in the partial rigidity of the sheet member.

Means for Solving the Problems

[0006] The main invention for achieving the above object is a nonwoven fabric layer having a plurality of non-thermally bonded fibers A sheet member having The average fiber length of the non-thermally fused fibers is 5 mm or more, and the standard deviation of the fiber length of the non-thermally fused fibers is 5.5 or less and In the plurality of non-thermally fused fibers, the non-thermally fused fibers having a fiber length of less than 20.6 mm account for 90% by weight or more of the plurality of non-thermally fused fibers , No adhesive is provided on the sheet member which is a sheet member characterized by this. Other features of the present invention will be clarified by the descriptions in this specification and the attached drawings.

Advantages of the Invention

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

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0009] From the descriptions in this specification and the attached drawings, at least the following matters become clear. (Aspect 1) A sheet member having a non-thermally bonded fiber layer having a plurality of non-thermally bonded fibers, wherein an average fiber length of the non-thermally bonded fibers is 5 mm or more, and a standard deviation of fiber lengths of the non-thermally bonded fibers is 5.5 or less.

[0010] According to the sheet member of Aspect 1, since the average fiber length of the non-thermally bonded fibers constituting the non-woven fabric layer is 5 mm or more, the risk of non-thermally bonded fibers dropping off from the sheet member can be reduced as compared with the case where the average fiber length is shorter than 5 mm. Further, since the standard deviation of the fiber lengths of the non-thermally bonded fibers is 5.5 or less, it is easier to reduce the variation in the density of the non-thermally bonded fibers in the sheet member as compared with the case where the standard deviation of the fiber lengths of the non-thermally bonded fibers is greater than 5.5. 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 a partial change in the rigidity of the sheet member.

[0011] (Aspect 2) The sheet member of Aspect 1, wherein among the plurality of non-thermally bonded fibers, the non-thermally bonded fibers having a fiber length of less than 20.6 mm account for 90% by weight or more of the plurality of non-thermally bonded fibers.

[0012] According to the sheet member of Mode 2, it is easier to make the density of the non-thermally fused fibers in the sheet member uniform than when the non-thermally fused fibers having a fiber length of 20.6 mm or more occupy more than 10% by weight of the plurality of non-thermally fused fibers. Therefore, it is easier to further reduce the possibility of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member.

[0013] (Mode 3) In the plurality of non-thermally fused fibers, the non-thermally fused fibers having a fiber length of 12 mm or less occupy 50% by weight or more of the plurality of non-thermally fused fibers, and the sheet member is the sheet member of Mode 1 or 2.

[0014] According to the sheet member of Mode 3, it is easier to make the density of the non-thermally fused fibers in the sheet member uniform than when the non-thermally fused fibers having a fiber length of 12 mm or more occupy more than 50% by weight of the plurality of non-thermally fused fibers. Therefore, it is easier to reduce the possibility of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member.

[0015] (Mode 4) The plurality of non-thermally fused fibers do not have non-thermally fused fibers having a fiber length of 35 mm or more, and the sheet member is any one of the sheet members of Modes 1 to 3.

[0016] According to the sheet member of Mode 4, it is easier to make the density of the non-thermally fused fibers in the sheet member uniform than when having non-thermally fused fibers having a fiber length of 35 mm or more. Therefore, it is easier to reduce the possibility of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member.

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

[0018] According to the sheet member of Aspect 5, by forming the sheet member without using an adhesive, it is possible to suppress the hardening of the sheet member caused by the provision of the adhesive, and to reduce the risk of moisture absorption being hindered by the adhesive.

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

[0020] According to the sheet member of Aspect 6, when the fibers are intertwined with each other, voids are likely to be formed between the fibers, reducing the risk of the sheet member becoming hard and further reducing the risk of moisture absorption being hindered.

[0021] (Aspect 7) The sheet member according to any one of Aspects 1 to 6, characterized in that it does not have a portion where the non-thermally fused fibers are fused together.

[0022] According to the sheet member of Aspect 7, by not having a portion where the non-thermally fused fibers are fused together, the risk of the sheet member becoming hard is reduced, and the risk of moisture absorption being hindered by the fused portion of the non-thermally fused fibers is reduced.

[0023] (Aspect 8) The non-thermally fused fiber is a cotton fiber, has a substance different from the cotton fiber, and the substance has a size of 1 mm or more when viewed in the thickness direction, and is the sheet member according to any one of Aspects 1 to 7. 2

[0024] According to the sheet member of Aspect 8, the user can more easily recognize the presence of the sheet member by visually recognizing that a substance different from the cotton fiber is contained in the cotton fiber.

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

[0026] According to the sheet member of Aspect 9, in the sheet member, by making the basis weight of substances such as seed husks smaller than the basis weight of cotton fibers, it becomes easier to give the user the impression that the sheet member is a sheet made of natural materials, while reducing the risk of a decrease in the amount of water absorbed by the cotton fibers.

[0027] (Aspect 10) The sheet member according to any one of Aspects 1 to 9, wherein 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-thermally bonded fibers account for 90% by weight or more of the fibers constituting the sheet member.

[0028] According to the sheet member of Aspect 10, on at least one surface in the thickness direction, it becomes easier to reduce the risk of a partial decrease in the amount of water absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member.

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

[0030] According to the sheet member of Aspect 11, in the nonwoven fabric layer on the skin side of the sheet member, it is easy to absorb moisture such as the wearer's sweat, and the absorbed moisture can be easily transferred to the other layer on the non-skin side and evaporated. Therefore, when the sheet member comes into contact with the user's skin, it is easy to suppress the occurrence of sweating or causing discomfort to the user.

[0031] (Aspect 12) The average fiber length of the cotton fiber is shorter than the average fiber length of the heat-fusing fiber, and the cotton fiber is entangled with the heat-fusing fiber. The sheet member of Aspect 11 is characterized by this.

[0032] According to the sheet member of Aspect 12, since the cotton fiber with a short average fiber length is arranged to be covered from the non-skin side by the heat-fusing fiber with a long average fiber length, it is easy to suppress the cotton fiber from falling off to the outside (non-skin side) of the sheet member. Therefore, the density of the non-heat-fusing fiber in the skin-side layer of the sheet member is easily maintained in a uniform state, and it is easy to reduce the risk of a decrease in water absorption, uneven thickness, a change in rigidity, etc.

[0033] (Aspect 13) The value obtained by dividing the total weight of the cotton fiber by the weight of the sheet member is smaller than the value obtained by dividing the total weight of the heat-fusing fiber by the weight of the sheet member. The sheet member of Aspect 11 or 12 is characterized by this.

[0034] According to the sheet member of Aspect 13, it is possible to easily absorb moisture with cotton fibers having a small mass%, and to easily evaporate the absorbed moisture from the heat-fusing fibers having a large mass%. Therefore, the water evaporation property can be enhanced more than when the value obtained by dividing the total weight of the cotton fiber by the weight of the sheet member is made larger than the value obtained by dividing the total weight of the heat-fusing fiber by the weight of the sheet member.

[0035] (Aspect 14) The thickness of the non-woven fabric layer is thicker than the thickness of the other layers. The sheet member of any one of Aspects 11 to 13 is characterized by this.

[0036] According to the sheet member of Aspect 14, it is possible to make the contact with the skin softer than when the thickness of the non-woven fabric layer is made thinner than the thickness of the other layers on the skin-side surface in contact with the skin of the wearer. Also, it is possible to easily absorb moisture with the cotton fiber on the skin side and to enhance the water evaporation property.

[0037] (Aspect 15) The sheet member has a basis weight of 30 g / m 2 It is any of the sheet members of aspects 11 to 14, characterized by the following.

[0038] According to the sheet member of aspect 15, the higher the basis weight of the sheet member, the more likely the sheet member is to become hard. By setting the basis weight to 30 g / m 2 As follows, when the basis weight is 30 g / m 2 The sheet member can be made softer than when it is larger.

[0039] (Aspect 16) It is any of the sheet members of aspects 11 to 15, characterized in that the standard deviation of the fiber length of the heat-fused fiber is smaller than the standard deviation of the fiber length of the cotton fiber.

[0040] According to the sheet member of aspect 16, while reducing the variation in the density of the cotton fiber in the nonwoven fabric layer, the variation in the density of the heat-fused fiber in other layers can be further reduced. Therefore, it is easy to reduce the possibility of a partial decrease in the amount of moisture absorbed, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member across the entire sheet member.

[0041] (Aspect 17) It has a longitudinal direction and a lateral direction orthogonal to the thickness direction. The nonwoven fabric layer has a predetermined basis weight portion provided with the cotton fiber of a predetermined basis weight and a low basis weight portion where the basis weight of the cotton fiber is lower than that of the predetermined basis weight portion. When viewed in the thickness direction, it has 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. In the longitudinal direction, the predetermined basis weight portion and the low basis weight portion are alternately arranged, and in the lateral direction, the predetermined basis weight portion and the low basis weight portion are alternately arranged. The longitudinal length of the low basis weight portion is shorter than the average fiber length of the cotton fiber, and the lateral length of the low basis weight portion is shorter than the average fiber length of the cotton fiber. It is any of the sheet members of aspects 11 to 16, characterized by the above.

[0042] According to the sheet member of Aspect 17, in the thickness direction, the portion where the predetermined basis weight portion and the other layer overlap absorbs moisture such as sweat of the wearer's skin, and promotes the evaporation of the absorbed moisture from the low basis weight portion. Also, it facilitates the movement of moisture from the low basis weight portion to the non-skin side layer (other layer). Therefore, it is possible to reduce the risk of continuously retaining excessive moisture in the skin side layer and reduce the risk of stuffiness and rough skin. And, in the longitudinal and transverse directions, since the predetermined basis weight portion and the low basis weight portion are alternately arranged, it is possible to reduce discomfort and adverse effects on the wearer's skin over a wide range of the sheet member.

[0043] (Aspect 18) A disposable absorbent article comprising the sheet member according to any one of Aspects 1 to 17.

[0044] According to the absorbent article of Aspect 18, by reducing 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 a partial change in the rigidity of the sheet member, it is possible to reduce the risk of a decrease in absorbency and a decrease in touch feeling of the disposable absorbent article.

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

[0046] According to the sheet member of Aspect 19, it is easier to give the user who visually recognizes a substance such as a seed husk the impression that the sheet member is a sheet made of natural materials. Thereby, it is easier to evoke an image of being gentle and safe for the skin and nature.

[0047] (Aspect 20) The nonwoven fabric layer has a substance different from the cotton fiber, and the substance has a size of 1 mm or more in the thickness direction, and the other layer does not have the substance. The sheet member according to any one of Aspects 1 to 17. 2

[0048] ​According to the sheet member of Embodiment 20, foreign matters can be visually recognized on one side (skin side) in the thickness direction, while foreign matters cannot be visually recognized on the other side (non-skin side) in the thickness direction. Therefore, it becomes easier for the user to immediately recognize which side in the thickness direction the non-woven fabric layer is present on.

[0049] ===Embodiment=== Hereinafter, the sheet member for the absorbent article according to the present embodiment will be described by taking an adult disposable pants-type diaper 1 (hereinafter, also simply referred to as "diaper 1") as an example of the absorbent article, and as an example of the sheet member, the sweat-absorbing sheets (sheet portions 25, 35) of the waist portions 20, 30 for the diaper 1 will be described. However, the absorbent article according to the present embodiment is not limited to the above, and for example, it can also be applied to disposable pants-type diapers for infants, short-type napkins, tape-type disposable diapers, etc. Further, as the sheet member, any member that can come into contact with the skin side of each absorbent article may be used regardless of the sweat-absorbing sheet.

[0050] <Basic Configuration of Disposable Pants-Type Diaper 1> FIG. 1 is a schematic perspective view of the diaper 1 as viewed from the ventral side. FIG. 2 is a schematic plan view of the diaper 1 in a deployed and stretched state as viewed from the skin side of the wearer. FIG. 3 is a schematic cross-sectional view taken along line A-A in FIG. 2.

[0051] The "deployed state" of the diaper 1 means that by releasing the joining of the side joining portions SS (described later) provided on both sides in the left-right direction of the diaper 1 in the pants-type state of FIG. 1, the ventral waist portion 20 (described later) and the dorsal waist portion 30 (described later) are separated, and by opening the diaper 1 in the vertical direction, the diaper 1 is in a state of being deployed on a plane. Further, the "stretched state" of the diaper 1 means a state in which the product (diaper 1) is stretched without wrinkles. Specifically, it means a state in which the dimensions of each member (for example, the absorbent main body 10, the ventral waist portion 20, etc.) constituting the diaper 1 are extended until they coincide with or are close to the dimensions of the member alone.

[0052] Diaper 1 has a pant-like shape when worn as shown in Fig. 1, with vertical, horizontal, and front-back directions that intersect each other, and has a waist opening BH and a pair of leg openings LH. In the vertical direction, the side of the waist opening BH is the upper side, and the side that becomes the crotch side of the wearer is the lower side. In the front-back direction, the side that becomes the abdominal side of the wearer is the front side, and the side that becomes the back side is the rear side. Also, in the unfolded and extended state shown in Fig. 2, diaper 1 has a longitudinal direction, a horizontal direction, and a thickness direction (the direction penetrating the paper surface in Fig. 2) as three mutually orthogonal directions. 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 (rear side). Also, diaper 1 has a thickness direction in which materials are laminated as shown in Fig. 3. The side that contacts the wearer in the thickness direction is the skin side, and the opposite side is the non-skin side.

[0053] Diaper 1 has an absorbent body 10 and an outer cover 18. The outer cover 18 has a pair of waist portions 20, 30 and a crotch portion 40 located at the crotch of the wearer. The outer cover 18 is joined to the non-skin side surface of the absorbent body 10 with an adhesive or the like. Of the pair of waist portions 20, 30, the one located on the abdominal side (front side) of the wearer is also called the abdominal waist portion 20, and the one located on the back side (rear side) is also called the back waist portion 30. The abdominal waist portion 20 and the back waist portion 30 are joined by a pair of side joining portions SS on both side portions in the horizontal direction. Examples of the joining method by the side joining portion SS include a heat welding method, an ultrasonic welding method, and a joining method using an adhesive.

[0054] As shown in FIG. 3, the absorbent body 10 includes an absorbent core (absorbent) 11, a liquid-permeable topsheet 12 disposed closer to the skin side than the absorbent core 11, a liquid-impermeable backsheet 13 disposed closer to the non-skin side than the absorbent core 11, and an outer wrapper sheet 14. The absorbent core 11 may be any material that can absorb and hold excreted liquid. For example, it can be an object formed by shaping a liquid-absorbent material such as pulp fibers or superabsorbent polymer (SAP) into a predetermined shape. Further, the absorbent core 11 may be covered with a liquid-permeable sheet such as tissue paper or non-woven fabric. The topsheet 12 is formed of, for example, a non-woven fabric such as an air-through non-woven fabric or a spunbond non-woven fabric. The backsheet 13 is, for example, a liquid-impermeable and breathable film such as polyethylene or polypropylene. The outer wrapper sheet 14 is formed of, for example, a non-woven fabric equivalent to the topsheet 12.

[0055] As shown in FIG. 2, on both sides of the absorbent body 10 in the left-right direction, a plurality of elastic members 15 (e.g., thread rubber) that stretch along the longitudinal direction of the absorbent body 10 are provided around the legs. Further, an anti-leakage wall portion that can stand up on the skin side may be provided by providing, for example, an elastic member that stretches in the longitudinal direction inside the elastic members 15 around the legs in the left-right direction.

[0056] As shown in FIGS. 2 and 3, the outer package 18 includes 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 disposed from the ventral body circumference portion 20 through the crotch portion 40 to the dorsal body circumference portion 30 (FIG. 3). The width (length in the left-right direction) of the inner layer sheet 21 at the ventral body circumference portion 20 and the dorsal body circumference portion 30 is larger than the width (length in the left-right direction) of the inner layer sheet 21 at the crotch portion 40 (FIG. 2). As the inner layer sheet 21, an air-through non-woven fabric, a spunbond non-woven fabric, an SMS non-woven fabric (spunbond-meltblown-spunbond non-woven fabric), a waterproof film, etc. can be used.

[0058] As shown in FIGS. 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 body circumferential portion 20. The outer end (upper end) of the ventral outer layer sheet 22 in the longitudinal direction is folded back to the skin side. The folded portion 22r of the ventral outer layer sheet 22 wraps around 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 FIGS. 2 and 3, the dorsal outer layer sheet 32 is provided on the non-skin side of the inner layer sheet 21, and the dorsal outer layer sheet 32 and the inner layer sheet 21 constitute the dorsal body circumferential portion 30. The outer end (upper end) of the dorsal outer layer sheet 32 in the longitudinal direction is folded back to the skin side. The folded portion 32r of the dorsal outer layer sheet 32 wraps around the other end (outer end) of the inner layer sheet 21 in the longitudinal direction. Note that the outer end (upper end) of the dorsal 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, an air-through nonwoven fabric, a spunbond nonwoven fabric, an SMS nonwoven fabric (spunbond-meltblown-spunbond nonwoven fabric), etc. can be used.

[0061] The ventral body circumferential portion 20 and the dorsal body circumferential portion 30 each have body circumferential elastic members 23, 33 that can expand and contract in the left-right direction. The plurality of body circumferential elastic members 23, 33 are arranged at intervals in the vertical direction 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 extended state in the left-right direction (see FIGS. 2 and 3). Therefore, the ventral body circumferential portion 20 and the dorsal body circumferential portion 30 expand and contract in the left-right direction and fit the wearer's body circumference. Note that examples of the body circumferential elastic members 23, 33 include thread-like elastic members such as thread rubber and elongated elastic sheets.

[0062] In addition, in the present embodiment, in the dorsal torso portion 30, the hind-leg-around elastic member 34 is provided between the inner layer sheet 21 and the dorsal outer layer sheet 32. The hind-leg-around elastic member 34 may be, for example, a plurality of thread rubbers, a stretchable belt-shaped elastic sheet, or the like. The hind-leg-around elastic member 34 is joined and fixed by an adhesive such as a hot melt adhesive in an extended state.

[0063] Also, in the present embodiment, in a predetermined region on the most skin side of the ventral torso portion 20 and the dorsal torso portion 30, sheet portions 25 and 35 that are easy to absorb the sweat of the wearer are provided (the hatched portions in FIG. 2). The sheet portions 25 and 35 are arranged closer to the skin side 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 belt-shaped sheet members arranged 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 the diaper 1 has been described above. However, the configuration of the diaper 1 described above is an example and is not limited thereto. For example, in the diaper 1 of the present embodiment, the exterior body 18 having three parts, the ventral torso portion 20, the dorsal torso portion 30, and the crotch portion 40 connecting them, is provided. However, it is not limited to this. For example, the ventral torso portion 20 and the dorsal torso portion 30 may be configured as separate members, and the diaper may have a configuration in which the non-skin side surface of the absorbent body 10 is exposed in the crotch portion, or the diaper may have an exterior member configured as a single member continuous from the ventral torso portion 20 to the dorsal torso portion 30.

[0065] <Regarding the sheet portions 25 and 35> Hereinafter, the specific configurations of the seat portions 25 and 35 according to this embodiment will be described. In this embodiment, the seat portion 25 provided in the ventral trunk circumference portion 20 and the seat portion 35 provided in the dorsal trunk circumference portion 30 have substantially the same configuration. Therefore, in the following description, for the content common to both the seat portion 25 and the seat portion 35, only the seat portion 25 will be described on behalf of both. For the seat portion 35, specific descriptions will be omitted, such as indicating the reference numerals of the members corresponding to the seat portion 25 in parentheses as necessary.

[0066] FIG. 4 is a schematic cross-sectional view of the seat portion 25. FIG. 5A is a magnified view of the seat portion 25 photographed from the skin side. FIG. 5B is an enlarged schematic view of a part of FIG. 5A. As described above, in this embodiment, the seat portion 25 constitutes a part of the surface that contacts the skin of the wearer in the ventral trunk circumference portion 20 (see FIG. 3). And as shown in FIG. 4, the seat portion 25 has a skin-side layer 25a arranged to contact the skin of the wearer and a non-skin-side layer 25b located on the non-skin side in the thickness direction of the skin-side layer 25a.

[0067] The skin-side layer 25a is, for example, a non-thermally fused fiber layer made of non-thermally fused fibers such as cotton fibers as the base fibers. Cotton fibers are soft, have a rounded fiber shape, and have high water absorption. Therefore, by using cotton fibers as the base fibers of the skin-side layer 25a that contacts the skin of the wearer, the contact with the wearer's skin is good, and the irritation to the wearer's skin during wearing can be reduced. Here, the above-mentioned "base material" means a material whose proportion (weight%) in each layer (skin-side layer 25a, non-skin-side layer 25b) exceeds 50%.

[0068] As the base fibers of the non-skin-side layer 25b, thermally fusible fibers such as polyester fibers, polypropylene fibers, polyethylene fibers, polyurethane fibers, and composite fibers thereof can be used. Hereinafter, the base fibers of the skin-side layer 25a will also be referred to as "skin-side fibers", and the base fibers of the non-skin-side layer 25b will also be referred to as "non-skin-side fibers". Also, the skin-side layer 25a will also be referred to as the "non-woven fabric layer 25a", and the non-skin-side layer 25b will also be referred to as the "other layer 25b".

[0069] In addition, for each of the above fibers, either one with a hydrophilic treatment on the fiber surface or one without a hydrophilic treatment may be used, but at least the skin-side fibers preferably have hydrophilicity.

[0070] Further, in the sheet portion 25 (sheet member) of the present embodiment, the skin-side fibers (cotton fibers) 25as, which are the base fibers of the skin-side layer 25a, have a portion that is intertwined with the non-skin-side fibers 25bs, which are the base fibers of the non-skin-side layer 25b (see FIG. 4). As a method for integrating the skin-side layer 25a and the non-skin-side layer 25b by intertwining, for example, a known water jet intertwining method or the like can be used.

[0071] Moreover, the skin-side layer 25a has a predetermined basis weight portion 25aP provided with skin-side fibers 25as of a predetermined basis weight and a low basis weight portion 25aL having a lower basis weight of skin-side fibers 25as than the predetermined basis weight portion 25aP. Then, as shown in FIGS. 4 and 5, when the sheet portion 25 (diaper 1) is viewed in the thickness direction, there are 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 of the skin-side layer 25a overlaps with the non-skin-side layer 25b, during wearing, the predetermined basis weight portion 25aP in the sheet portion 25 abuts against the skin of the wearer, and the water absorption and touch of the sheet portion 25 (diaper 1) during wearing can be improved. On the other hand, by having a portion where the low basis weight portion 25aL and the non-skin-side layer 25b overlap, during wearing, the portion where the predetermined basis weight portion 25aP and the non-skin-side layer 25b overlap when viewed in the thickness direction absorbs moisture such as sweat from the skin of the wearer, and it becomes easier to promote the evaporation of the moisture absorbed by the predetermined basis weight portion 25aP from the low basis weight portion 25aL where the basis weight of the skin-side fibers 25as is low, or to promote the movement of moisture from the low basis weight portion 25aL to the non-skin-side layer 25b.

[0072] Note that the "low basis weight portion 25aL" may be any portion where the basis weight of the skin-side fibers 25as is lower than that of the predetermined basis weight portion 25aP, including the case where the skin-side fibers 25as are provided in the low basis weight portion 25aL and the case where the skin-side fibers 25as are not provided. In any case, it is preferable that the low basis weight portion 25aL is a portion recessed on the non-skin side from the predetermined basis weight portion 25aP (see Fig. 4). Since the low basis weight portion 25aL is recessed on the non-skin side from the predetermined basis weight portion 25aP, when worn, the predetermined basis weight portion 25aP in the skin-side layer 25a of the sheet portion 25 becomes a portion that easily contacts the wearer's skin, improving the skin contact with the wearer, while the low basis weight portion 25aL becomes a portion that hardly contacts the wearer's skin. Therefore, it becomes easier to move moisture such as sweat and humidity to the non-skin side layer 25b through the low basis weight portion 25aL with few skin-side fibers 25as. Even when the skin-side layer 25a absorbs moisture such as sweat during wear, the portion of the skin-side layer 25a that contacts the wearer's skin is reduced, and even when the skin-side fibers 25as of the skin-side layer 25a absorb moisture, the fear of making the wearer feel sticky on the skin can be reduced.

[0073] The low basis weight portion 25aL of the present embodiment is a portion where almost no skin-side fibers 25as are provided, and there is a portion where the basis weight of the skin-side fibers 25as is 0 (zero). Plainly speaking, 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 visually recognized through the low basis weight portion 25aL (see Fig. 5A). Note that since the skin-side fibers 25as are soft fibers and have some fluidity, the portion where the basis weight of the skin-side fibers 25as is 0 (zero) does not mean that there are completely no (zero) skin-side fibers 25as, and it may be a portion where several skin-side fibers 25as are provided in the low basis weight portion 25aL.

[0074] <Details of the configuration of the skin-side fibers> As described above, in the sheet portion 25 of the present embodiment, the skin-side layer 25a (non-woven fabric layer 25a) is composed of non-thermally fused fibers such as cotton fibers as base fibers. And, in the present embodiment, the non-thermally fused fibers constituting the non-woven fabric layer 25a have a shorter average fiber length and less variation in fiber length compared to conventional general non-thermally fused fibers. Hereinafter, the detailed configuration of the base fibers (skin-side fibers 25as) of the non-woven fabric layer 25a will be described.

[0075] First, as a conventional general non-thermally fused fiber, the manufacturing method of cotton fibers will be briefly described. When manufacturing cotton fibers, first, raw cotton as a raw material is obtained. Next, foreign substances such as seeds, leaves, and stems contained in the raw cotton are removed, and degreasing and bleaching are performed to produce bleached cotton. Next, this bleached cotton is hydroentangled with a base non-woven fabric to produce a cotton material.

[0076] Normally, when producing bleached cotton, a carding process is performed in which the fibers of the compressed raw cotton are scraped and loosened while removing foreign substances using a carding machine (not shown) provided with a rotating body having a plurality of spines on its peripheral surface. At this time, the short fiber waste scraped by the carding machine is also called "comanoil". In the sheet portion 25 of the present embodiment, this comanoil can be used as the base fiber of the non-woven fabric layer 25a. Of course, the non-woven fabric layer 25a may be composed of non-thermally fused fibers other than comanoil.

[0077] FIG. 6A shows data obtained by measuring the fiber length distribution of the skin-side fibers constituting the nonwoven fabric layer 25a (skin-side layer 25a) in the present embodiment, and FIG. 6B shows data obtained by measuring the fiber length distribution of the skin-side fibers in the sheet member of the comparative example. Further, FIG. 7A is a graph representing the fiber length distribution of FIG. 6A (present embodiment), and FIG. 7B is a graph representing the fiber length distribution of FIG. 6B (comparative example). Note that 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) using conventional general non-thermally bonded fibers (such as cotton fibers) as the base fibers (skin-side fibers) of the skin-side layer. That is, the sheet member of the comparative example is different from the sheet part 25 (sheet member) of the present embodiment in that normal non-thermally bonded fibers (such as cotton fibers) different from corn oil are used as the base fibers constituting the skin-side layer. In addition, the data of the fiber length distribution shown in FIGS. 6A and 6B can be obtained by measuring the fiber length based on the method of 7.2 Fiber length sorter defined in "JIS L1019:2006 Test methods for cotton fibers".

[0078] As shown in FIGS. 6 and 7, in the sheet part 25 of the present embodiment, the average fiber length of the base fibers (non-thermally bonded fibers) constituting the nonwoven fabric layer 25a 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-thermally bonded 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-thermally bonded fibers, which are the base fibers of the nonwoven fabric layer 25a of the present embodiment, have a shorter average fiber length and a smaller variation in distribution than the non-thermally bonded fibers, which are the base fibers of the nonwoven fabric layer of the comparative example.

[0079] Generally, the greater the variation in the density of the fibers constituting the sheet member, the more likely it is that the amount of moisture absorbed by the sheet member will partially decrease, the thickness will become uneven, the rigidity will become partially higher or lower. In contrast, in the present embodiment, the variation in the fiber length of the non-thermally fused fibers constituting the non-woven fabric layer 25a (skin-side layer 25a) in the sheet portion 25 (sheet member) is smaller than the variation in the fiber length of the non-thermally fused fibers in the conventional sheet member. Referring to the data in FIG. 6, specifically, if the standard deviation of the fiber length of the non-thermally fused fibers is about 4.69, 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 a partial change in the rigidity of the sheet member compared to the conventional case. Even if there is a variation of about ±10% in the magnitude of the standard deviation due to errors during fiber length measurement, etc., if the standard deviation of the fiber length of the non-thermally fused fibers is 5.5 or less, the variation in fiber length is smaller than when the standard deviation of the fiber length of the non-thermally fused fibers is greater than 5.5, and it is easier to suppress a decrease in the absorption amount, etc. And in the non-woven fabric layer 25a of the present embodiment, while making the average fiber length of the fibers uniform and short to reduce the variation, the fiber length is prevented from becoming excessively short. Specifically, by having the average fiber length of the non-thermally fused fibers be 5 mm or more, the risk of non-thermally fused fibers falling off from the sheet member can be reduced compared to the case where the average fiber length of the non-thermally fused fibers is shorter than 5 mm. Also, since the sheet member has non-thermally fused fibers, even when heat is applied to the sheet member, it becomes less likely to form partially solidified portions due to fusion compared to the case where it does not have non-thermally fused fibers. Thus, it is possible to more easily 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 a partial change in the rigidity of the sheet member.

[0080] Here, according to "Hibiki Hira. Characteristics of Cotton Fibers from a Practical Perspective. Journal of the Fiber Society. 2006, Vol. 62, No. 7, P-191", the fiber length can be classified into the following five categories. That is, it is classified into five categories: short fibers (less than 20.6 mm), medium fibers (20.6 - 25.4 mm), medium-long fibers (26.2 - 27.8 mm), long fibers (28.6 - 34.1 mm), and extra-long fibers (34.9 mm or more).

[0081] In the sheet member of the comparative example, among the plurality of non-thermally fused fibers constituting the non-woven fabric layer, the proportion (by weight) of fibers with a fiber length of less than 20.6 mm, which are classified as short fibers, is about 76.3% (see Fig. 6B). In contrast, in the present embodiment, among the plurality of non-thermally fused fibers constituting the non-woven fabric layer 25a of the sheet portion 25, the proportion (by weight) of fibers with a fiber length of less than 20.6 mm, which are classified as short fibers, is about 94.4% (see Fig. 6A). That is, in the present embodiment, short fibers with an average fiber length of less than 20.6 mm account for at least 90% by weight or more of the plurality of non-thermally fused fibers. From this, it can be seen that the non-woven fabric layer 25a of the present embodiment contains more short fibers than conventional non-woven fabrics. Therefore, in the sheet portion 25 (sheet member) of the present embodiment, it is easier to make the density of the non-thermally fused fibers in the sheet member uniform than when non-thermally fused fibers with a fiber length of 20.6 mm or more account for more than 10% by weight of the plurality of non-thermally fused fibers. Thereby, it is easier to reduce the possibility of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member.

[0082] Also, focusing on the non-thermally fused fibers with a fiber length of 12 mm or less, in the sheet member of the comparative example, the proportion (by weight) of the fibers with a fiber length of 12 mm or less is 45.6%, which is less than 50%, which is half of the total weight (see Fig. 6B). On the other hand, in the sheet portion 25 of the present embodiment, the proportion (by weight) of the fibers with a fiber length of 12 mm or less is 75% or more, greatly exceeding 50% (see Fig. 6A). Thus, in the sheet portion 25 (sheet member), the non-thermally fused fibers with a fiber length of 12 mm or less are 50% by weight or more of the plurality of non-thermally fused fibers, and it is easier to make the density of the non-thermally fused fibers uniform compared to the case where the non-thermally fused fibers with a fiber length of 12 mm or less are less than 50% by weight as in the conventional sheet member. Therefore, it is easier to reduce the possibility of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member.

[0083] Among the non-thermally fused fibers included in the sheet member of the comparative example, the longest fiber has a fiber length of 36 mm, whereas among the non-thermally fused fibers included in the sheet portion 25 (sheet member) of the present embodiment, the longest fiber has a fiber length of 34 mm (see Figs. 6A and 6B). That is, the sheet portion 25 (sheet member) of the present embodiment did not have non-thermally fused fibers with a fiber length of 35 mm or more. Thus, according to the sheet portion 25 (sheet member) of the present embodiment, for the plurality of non-thermally fused fibers, it is easier to make the density of the non-thermally fused fibers in the sheet member uniform than in the case of having non-thermally fused fibers with a fiber length of 35 mm or more. Therefore, it is easier to reduce the possibility of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member.

[0084] Also, as described with reference to FIG. 4, the sheet portion 25 of the present embodiment is formed by causing a plurality of fibers to interlace with each other by means of a water flow. That is, the sheet portion 25 (sheet member) is formed by interlacing the fibers with each other without using an adhesive. According to such a sheet member, it is possible to suppress the hardening of the sheet member due to the provision of an adhesive, and to reduce the risk of the absorption of moisture being hindered by the adhesive.

[0085] And according to the sheet portion 25 (sheet member) of the present embodiment, since the fibers are interlaced with each other, a large number of voids are likely to be formed between the fibers (see FIG. 4). While reducing the risk of the sheet member becoming hard, it is possible to further reduce the risk of the absorption of moisture being hindered.

[0086] Also, the sheet portion 25 (sheet member) of the present embodiment is formed without the non-thermally bonded fibers fusing to each other. According to such a sheet member, since it does not have a portion where the non-thermally bonded fibers are fused to each other, it is possible to reduce the risk of the sheet member becoming hard, and to reduce the risk of the absorption of moisture being hindered by the portion where the non-thermally bonded fibers are fused to each other.

[0087] Also, the non-woven fabric layer 25a (skin-side layer 25a) of the sheet portion 25 contains a substance different from cotton fibers. Although it has been described that the non-woven fabric layer 25a contains the comanoil removed in the carding process, at this time, foreign substances such as seed husks, leaves, and stems removed from the raw cotton together with the comanoil may be mixed into the non-woven fabric layer 25a. And the size of the substance may be 1 mm 2 or more. In this case, when viewed in the thickness direction, on the surface of the sheet portion 25 (sheet member), 1 mm 2It becomes easier to visually recognize a state in which substances having the above size are present at multiple points. By visually recognizing that substances such as seed husks and leaves are contained in the non-thermally fused fibers (cotton fibers), the user can more easily recognize the presence of the sheet member. Note that substances such as seed husks removed from raw cotton in the carding process may still have a color such as brown without completely losing their color even after being bleached. In this case, the substance becomes more easily visible.

[0088] Also, since the substance contained in the sheet portion 25 (sheet member) is at least one of a leaf, a seed husk, or a stem, it becomes easier to give the user who visually recognizes the substance an impression that the sheet member is a sheet made of natural materials. Thereby, it is possible to more easily evoke an image of being gentle and safe for the skin and nature.

[0089] Further, in the entire sheet portion 25 (sheet member), it is preferable that the basis weight of substances such as seed husks is smaller than the basis weight of the non-thermally fused fibers (cotton fibers). If the basis weight of substances such as seed husks is larger than the basis weight of cotton fibers, the proportion of foreign substances contained in the sheet member becomes large and is likely to be conspicuous, which may cause concerns to the user such as a decrease in the amount of water absorbed by the cotton fibers. On the other hand, if the basis weight of substances such as seed husks is smaller than the basis weight of the non-thermally fused fibers (cotton fibers), it is possible to reduce the fear of a decrease in the amount of water absorbed by the cotton fibers while making it easier to give the user an impression that the sheet member is a sheet made of natural materials.

[0090] Further, when the sheet part 25 (sheet member) is trisected in the thickness direction, in the layer having at least one outer surface, it is preferable that the non-thermally fused fibers (cotton fibers) account for 90% by weight or more of the fibers constituting the sheet part 25. For example, when the sheet part 25 (sheet member) is trisected in the thickness direction as shown in FIG. 4, from the skin side toward the non-skin side in order, they are the first layer TA1, the second layer TA2, and the third layer TA3. In this case, the first layer TA1 is a layer overlapping with the skin-side layer 25a, and the third layer TA3 is a layer overlapping with the non-skin side layer 25b. And in the present embodiment, the first layer TA1 facing the outside (skin side) in the thickness direction is a nonwoven fabric (nonwoven fabric layer 25a) containing non-thermally fused fibers (cotton fibers), and 90% by weight or more of the fibers constituting the nonwoven fabric are non-thermally fused fibers (cotton fibers).

[0091] For such a sheet part 25 (sheet member), on at least one surface in the thickness direction (the first layer TA1 in FIG. 4), it becomes easier to reduce the possibility of a partial decrease in the amount of moisture absorbed by the sheet member, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member. In the sheet part 25 (sheet member), a layer of thermally fused fibers may be disposed on the skin side in the thickness direction, and a layer of non-thermally fused fibers (cotton fibers) may be disposed on the non-skin side in the thickness direction. In this case, 90% by weight or more of the fibers constituting the third layer TA3 facing the outside (non-skin side) in the thickness direction are non-thermally fused fibers (cotton fibers), and it becomes possible to obtain the same effects as in the above case according to the use of the sheet member.

[0092] Further, the sheet part 25 (sheet member) of the present embodiment has a skin-side layer 25a (nonwoven fabric layer 25a) which is a layer capable of contacting the skin side of the wearer when the diaper 1 is worn or the like, and a non-skin side layer 25b (other layer 25b) provided on the non-skin side of the skin-side layer 25a. And while 90% by weight or more of the fibers constituting the skin-side layer 25a (nonwoven fabric layer 25a) are a plurality of non-thermally fused fibers (cotton fibers), 90% by weight or more of the fibers constituting the non-skin side layer 25b (other layer 25b) are a plurality of thermally fused fibers.

[0093] That is, on the skin side of the sheet portion 25 (sheet member), a non-woven fabric layer 25a mainly composed of cotton fibers with good liquid absorbency is provided, and on the non-skin side of the sheet portion 25 (sheet member), another layer 25b mainly composed of heat-sealable fibers with good liquid transpiration is provided. By having such a configuration, in the non-woven fabric layer 25a on the skin side of the sheet portion 25 (sheet member), it is easy to absorb moisture such as the wearer's sweat, and the absorbed moisture can be easily moved to the other layer 25b on the non-skin side and transpired. Therefore, when the skin side of the sheet portion 25 comes into contact with the wearer's skin, it is easy to suppress the occurrence of stuffiness or discomfort to the wearer.

[0094] At this time, the average fiber length of the non-heat-sealable fibers (cotton fibers) constituting the skin-side layer 25a (non-woven fabric layer 25a) is shorter than the average fiber length of the heat-sealable fibers constituting the non-skin-side layer 25b (the other layer 25b), and it is preferable that the non-heat-sealable fibers (cotton fibers) and the heat-sealable fibers are intertwined with each other. With such a configuration, in the sheet portion 25 (sheet member), the non-heat-sealable fibers (cotton fibers) with a short average fiber length are covered from the non-skin side by the heat-sealable fibers with a long average fiber length. Therefore, it is easy to suppress the non-heat-sealable fibers (cotton fibers) from falling off to the outside (non-skin side) of the sheet member when the diaper 1 is worn. And since the falling off of the non-heat-sealable fibers is suppressed and the fiber density in the skin-side layer 25a of the sheet member is easily maintained in a uniform state, it is easy to reduce the risk of a decrease in water absorption, uneven thickness, change in rigidity, etc.

[0095] Also, the skin-side layer 25a (non-woven fabric layer 25a) contains a substance (foreign matter) different from the above-mentioned non-heat-sealable fibers (cotton fibers) such as seed husks, leaves, and stems, while the non-skin-side layer 25b (the other layer 25b) does not contain such a substance. That is, the non-skin-side layer 25b (the other layer 25b) is 1 mm when viewed in the thickness direction. 2It does not have a substance of the above size. In such a sheet member, foreign matters are likely to be visually recognized on one side in the thickness direction (here, the skin side), while foreign matters are less likely to be visually recognized on the other side in the thickness direction (non-skin side). Therefore, it becomes easier for the user to immediately recognize on which side in the thickness direction the layer of the non-thermally bonded fiber nonwoven fabric exists.

[0096] Also, in the sheet part 25 (sheet member), the value obtained by dividing the total weight of the non-thermally bonded fibers (cotton fibers) by the weight of the sheet member is preferably smaller than the value obtained by dividing the total weight of the thermally bonded fibers by the weight of the sheet member. That is, the mass% of the non-thermally bonded fibers (cotton fibers) in the sheet part 25 (sheet member) is preferably smaller than the mass% of the thermally bonded fibers in the sheet part 25 (sheet member). In such a sheet member, it is possible to easily absorb moisture with non-thermally bonded fibers (cotton fibers) having a small mass% and easily evaporate the absorbed moisture from the thermally bonded fibers having a large mass% to the atmosphere side. Therefore, the water evaporation property can be improved more than when the value obtained by dividing the total weight of the cotton fibers by the weight of the sheet member is made larger than the value obtained by dividing the total weight of the thermally bonded fibers by the weight of the sheet member.

[0097] Also, when the sheet part 25 (sheet member) is in a natural state, the thickness of the skin-side layer 25a (nonwoven fabric layer 25a) is preferably thicker than the thickness of the non-skin-side layer 25b (other layer 25b). In FIG. 4, the thickness of the skin-side layer 25a (nonwoven fabric layer 25a) is thicker than the thickness of the non-skin-side layer 25b (other layer 25b). With such a configuration, it is possible to make the contact with the skin softer than when the thickness of the nonwoven fabric layer 25a is made thinner than the thickness of the other layer 25b on the skin side surface in contact with the wearer's skin. Also, it is possible to easily absorb moisture with the cotton fibers on the skin side and improve the water evaporation property.

[0098] In addition, for the measurement of the thickness of the nonwoven fabric layer 25a and the other layer 25b, after separating each layer, for the cross-section in the thickness direction of each layer, the thickness at a plurality of locations (for example, 10 locations) is measured using a microscope or the like, and the average value is obtained, and this value is taken as the thickness of each layer. Alternatively, for the sheet portion 25 (sheet member) in the natural state, a cross-section in the thickness direction may be photographed, and the average values of the thickness of the nonwoven fabric layer 25a and 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 preferably 30 g / m 2 or less. Generally, the larger the basis weight of the sheet member, the harder the sheet member tends to be. In the present embodiment, by setting the basis weight of the sheet portion 25 (sheet member) to 30 g / m 2 or less, the sheet member can be made softer than when the basis weight of the sheet member is greater than 30 g / m 2 .

[0100] Further, in the sheet portion 25 (sheet member), the standard deviation of the fiber length of the heat-fused fibers may be smaller than the standard deviation of the fiber length of the non-heat-fused fibers (cotton fibers). With such a sheet member, while reducing the variation in the density of the cotton fibers in the skin-side layer 25a (nonwoven fabric layer 25a), the variation in the density of the heat-fused fibers in the non-skin-side layer 25b (other layer 25b) can be further reduced. In this case, it is easy to reduce the possibility of a partial decrease in the amount of moisture absorbed, unevenness in the thickness of the sheet member, and a partial change in the rigidity of the sheet member across the entire sheet member.

[0101] Also, as described with reference to FIG. 4, a predetermined basis weight portion 25aP and a low basis weight portion 25aL are provided in the skin-side layer 25a (non-woven fabric layer 25a) of the sheet portion 25 (sheet member), and both have portions overlapping the non-skin-side layer 25b (other layer 25b) when viewed in the thickness direction. Then, as shown in FIGS. 5A and 5B, in the vertical direction (the up-and-down direction of the diaper 1), the predetermined basis weight portion 25aP and the low basis weight portion 25aL are alternately arranged, and in the horizontal direction (the left-and-right direction of the diaper 1), the predetermined basis weight portion 25aP and the low basis weight portion 25aL are alternately arranged. As a result, when worn, the portion where the predetermined basis weight portion 25aP and the non-skin-side layer 25b overlap when viewed in the thickness direction absorbs moisture such as sweat from the wearer's skin, and the moisture absorbed by the predetermined basis weight portion 25aP is easily evaporated from the low basis weight portion 25aL where the basis weight of the skin-side fibers 25as is low, and the movement of moisture from the low basis weight portion 25aL to the non-skin-side layer 25b is also facilitated. Therefore, it is possible to reduce the risk of the skin-side layer 25a continuously retaining excessive moisture, and to reduce the risk of the diaper 1 becoming stuffy or causing adverse effects such as skin roughness. And, by alternately arranging the predetermined basis weight portion 25aP and the low basis weight portion 25aL in the vertical direction and alternately arranging the predetermined basis weight portion 25aP and the low basis weight portion 25aL in the horizontal direction, it is possible to reduce discomfort and adverse effects on the skin of the wearer of the diaper 1 over a wide range in the sheet portion 25.

[0102] Furthermore, it is preferable that the length of the low basis weight portion 25aL in the vertical direction is shorter than the average fiber length of the non-thermally bonded fibers (cotton fibers), and the length of the low basis weight portion 25aL in the horizontal direction is shorter than the average fiber length of the non-thermally bonded fibers (cotton fibers). In the sheet portion 25 (sheet member) of the present embodiment, since there is a risk that the wider the low basis weight portion 25aL is, the easier it is for the non-thermally bonded fibers (cotton fibers) to fall off from the sheet member, by making the length of the low basis weight portion 25aL in the vertical direction and the length in the horizontal direction shorter than the average fiber length of the non-thermally bonded fibers (cotton fibers) respectively, the risk of cotton fibers falling off from the sheet member can be reduced.

[0103] <Regarding the arrangement of the sheet portion 25 in the diaper 1> Figures 8 to 11 are 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 characteristics.

[0104] (Modified Example 1) FIGS. 8A and 8B are diagrams for explaining Modified Example 1 of the arrangement of the sheet portion 25 of the present invention. In Modified Example 1, instead of providing a separate sheet member as the sheet portion 25, the folded-back portion 22r (32r) of the ventral outer layer sheet 22 (dorsal outer layer sheet 32) is used as the sheet portion 25 (35). In this Modified Example 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. And a joint portion (not shown) where the sheet portion 25 (35), which is a 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 surface side in the thickness direction are joined by welding or adhesion, and a non-joint portion (not shown) where the sheet portion 25 (35) and the inner layer sheet 21 (adjacent sheet member) are not joined by welding or adhesion. With such a configuration, the same operational effects as those of the above-described embodiment can be obtained in the sheet portion 25.

[0105] Note that the folded-back portion 22r (32r) that is the sheet portion 25 (35) of this modified example is a portion with strong tightening in the ventral body circumference portion 20 (dorsal body circumference portion 30). Because the skin-side layer 25a is present on the skin contact surface of such a portion, the wearer can more vividly feel the softness of the skin-side fibers 25as such as cotton fibers. Also, due to the non-joint portion, it becomes easier to follow the movement of the body circumference, so the friction with the skin can be reduced and the fuzzing of the skin-side fibers 25as such as cotton fibers can be suppressed. Note that in Modified Example 1, the sheet portion 25 (35) is configured to replace the folded-back portion 22r (32r), but it is not limited to this. Regardless of whether the diaper 1 has the folded-back portion 22r (32r) or not, the sheet portion 25 (35) may be arranged at the position shown in FIG. 8.

[0106] (Modified Example 2) FIG. 9 is a diagram for explaining a second modification of the arrangement of the sheet portion 25 of the present invention. In the second modification shown in FIG. 9, the sheet portion 25 (35) is not provided up to both left and right ends of the ventral body circumferential portion 20 (dorsal body circumferential portion 30), but is provided at the central portion in the left-right direction of the ventral body circumferential portion 20 (dorsal body circumferential portion 30) and so as to straddle 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 portion where the unevenness is relatively large, by arranging the sheet portion 25 (35) so as to cover at least all of the upper end 10e, the friction against the skin during wearing can be suppressed, and the irritation given to the skin can be reduced.

[0107] (Modification 3) FIG. 10 is a diagram for explaining a third modification of the arrangement of the sheet portion 25 of the present invention. In the third modification shown in FIG. 10, a sheet member serving as the sheet portion 25 (35) is provided between the absorbent body 10 and the inner layer sheet 21. Further, the sheet member serving as the sheet portion 25 is provided in the ventral body circumferential portion 20 between one end in the left-right direction and the other end of the pair of side joining portions SS, and in the region from the upper end to the lower end in the vertical direction of the pair of side joining portions SS. In the dorsal body circumferential portion 30, the sheet member serving as the sheet portion 35 is provided between one end in the left-right direction and the other end of the pair of side joining portions SS, and in the region from the upper end to the vicinity of the lower end in the vertical direction of the pair of side joining portions SS. With such a configuration, the skin-side layer 25a exists in most of the skin contact surfaces in the regions of the ventral body circumferential portion 20 (dorsal body circumferential portion 30) other than the region where the absorbent body 10 is arranged, and the feel of the skin is improved. Further, since the sheet portion 25 (35) and the inner layer sheet 21 have a non-joined portion that is not joined by welding or adhesion, the sheet portion 25 (35) can easily follow the movement of the wearer's body circumference, and the friction with the skin can be reduced. Thus, even if the ratio of the skin-side layer 25a in contact with the skin increases, the fluffing of the skin-side fibers 25as such as cotton fibers can be suppressed. In the body circumferential portions 20 and 30, instead of the inner layer sheets 21 and 31, the sheet portions 25 and 35 may be arranged as the sheets located closest to the skin side of the body circumferential portions 20 and 30.

[0108] In addition, when the non-skin-side fiber 25bs is a thermoplastic fiber, the diaper 1 has an adjacent member provided at a position overlapping the sheet portion 25 when viewed in the thickness direction, and the diaper 1 is provided with a welded joint portion where the sheet portion 25 and the adjacent member are welded and joined in the thickness direction. The diaper 1 may be configured such that at least a part of the welded joint portion overlaps a portion where the low basis weight portion 25aL and the non-skin-side layer 25b overlap when viewed in the thickness direction. For example, in Modifications 1 to 3 shown in FIGS. 8 to 10, when the inner layer sheet 21 (or the ventral outer layer sheet 22) at a position overlapping the sheet portion 25 of the ventral body circumferential portion 20 is used as the adjacent member when viewed in the thickness direction, a welded joint portion (not shown) where the sheet portion 25 and the inner layer sheet 21 (or the ventral outer layer sheet 22) are welded and joined in the thickness direction may be provided. In such a case, it is preferable that at least a part of the welded joint portion overlaps a portion where the low basis weight portion 25aL and the non-skin-side layer 25b of the sheet portion 25 overlap when viewed in the thickness direction. Thereby, it is possible to reduce the risk of a decrease in the joining strength of the welded joint portion for welding the sheet portion 25 and the inner layer sheet 21 (or the outer layer sheet 22).

[0109] In the above-described embodiments and Modifications 1 to 3, the sheet portion 25 is provided at the ventral body circumferential portion 20 and the sheet portion 35 is provided at the dorsal body circumferential portion 30, but the present invention is not limited to this. In each diaper 1, a configuration may be adopted in which only the sheet portion 25 is provided at the ventral body circumferential portion 20 and the sheet portion 35 is not provided at the dorsal body circumferential portion 30, or a configuration may be adopted in which only the sheet portion 35 is provided at the dorsal body circumferential portion 30 and the sheet portion 25 is not provided at the ventral body circumferential portion 20.

[0110] (Modification 4) FIG. 11 is a diagram for explaining Modification 4 of the arrangement of the sheet portion 25 of the present invention. In Modification 4 shown in FIG. 11, the sheet portion 25 is provided as the top sheet 12 of the absorbent body 10. Since the top sheet 12 is a member that contacts the skin of the wearer in the absorbent body 10, by providing the sheet portion 25 as the top sheet 12, the texture can be improved by the skin-side fibers 25as of the skin-side layer 25a, and the discomfort to the skin of the wearer and the adverse effects on the skin of the wearer can be reduced.

[0111] Note that the diaper 1 of Modification Example 4 shown in FIG. 11 may have a squeezing member having a portion (not shown) squeezed in the thickness direction. Examples of the squeezing member include members such as the absorbent core 11. In the diaper 1, a sheet portion 25 (top sheet 12) is provided on the skin side of the squeezing member (absorbent core 11), and a portion where the low basis weight portion 25aL and the non-skin side layer 25b overlap when viewed in the thickness direction may have a portion that overlaps with the squeezed portion of the squeezing member (absorbent core 11). Generally, since the squeezed portion is a portion with a high fiber density, it becomes a portion that easily absorbs moisture by capillary action. Therefore, by having the squeezing member (absorbent core 11) have a portion with a high density due to squeezing, it becomes easier to move moisture from the sheet portion 25 (top sheet 12) to the squeezing member located on the non-skin side of the sheet portion 25.

[0112] ===Others=== The above embodiments are for facilitating the understanding of the present invention and are not for limiting the interpretation of the present invention. The present invention can be changed and improved without departing from its gist, and it goes without saying that equivalents of the present invention are included therein.

Explanation of Reference Numerals

[0113] 1 Diaper (pant-type disposable diaper, disposable absorbent article), 10 Absorbent main body, 10e Upper end, 11 Absorbent core (absorbent body), 12 Top sheet, 13 Back sheet, 14 Outer packaging sheet, 15 Elastic member around the legs, 18 Outer package, 20 Abdominal side body circumference part, 20e Upper end, 21 Inner layer sheet, 22 Abdominal side outer layer sheet, 22r Folded-back portion, 23 Body circumference elastic member, 25 Sheet portion (sheet member), 25a Skin side layer (non-woven fabric layer), 25aL Low basis weight portion, 25aP Predetermined basis weight portion, 25as muscle-side fibers (cotton fibers, non-thermally fused fibers), 25b non-muscle-side layer (other layer), 25bs non-muscle-side fibers, 30 dorsal torso portion, 32 dorsal outer layer sheet, 32r folded-back portion, 33 torso elastic member, 34 hind leg elastic member, 35 seat portion (seat member), 40 lower thigh portion, SS side joint (joint)

Claims

1. A sheet member having a nonwoven fabric layer having a plurality of non-thermally fusible fibers, The average fiber length of the non-thermal fusible fibers is 5 mm or more, The standard deviation of the fiber length of the non-thermal fusible fibers is 5.5 or less; Among the plurality of non-thermal fusible fibers, the non-thermal fusible fibers having a fiber length of less than 20.6 mm account for 90% by weight or more of the plurality of non-thermal fusible fibers, The sheet member is characterized in that no adhesive is provided on the sheet member.

2. The sheet member according to claim 1, A sheet member, wherein, among the plurality of non-thermal fusion fibers, the non-thermal fusion fibers having a fiber length of 12 mm or less account for 50% by weight or more of the plurality of non-thermal fusion fibers.

3. The sheet member according to claim 1, The sheet member is characterized in that the plurality of non-thermal fusible fibers do not include non-thermal fusible fibers having a fiber length of 35 mm or more.

4. A sheet member according to claim 1, A sheet member characterized in that the non-thermofusible fibers are entangled with each other.

5. The sheet member according to claim 1, A sheet member having no portions where the non-thermally fusible fibers are fused to each other.

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

7. A disposable absorbent article comprising a sheet member described in any one of claims 1 to 6.

Images