Disposable diapers (underwear style)

Abstract

The invention relates to a disposable diaper shaped in the form of underwear (1) comprising an absorbent body (10), an abdominal waistband (20), a back waistband (30), and elastic waistband components (23, 33) which can expand and contract in the transverse direction, wherein: the elastic waistband components (23, 33) are arranged between the skin-contacting sheet and the non-skin-contacting sheet; the back waistband (30) has openings (50) which do not penetrate the skin-contacting sheet (31) and the non-skin-contacting sheet (32) in the thickness direction of the sheets; the openings (50) overlap the absorbent core (11) in the transverse direction, and are located at the top of the absorbent core (11) in the vertical direction; the openings (50) overlap at least one elastic waistband component (33) in the vertical direction; and the elastic component of the lumbar region (33) is discontinuous, at the openings (50), in the horizontal direction.

Description

Pants-type disposable diapers

[0001] The present invention relates to a pants-type disposable diaper.

[0002]

[0003] Conventionally, absorbent articles such as diapers having openings in the waist area to improve breathability have been known. For example, Patent Document 1 discloses an absorbent article in which through-holes overlap with elastic members in the vertical direction and the elastic members are discontinuous within the through-holes in the horizontal direction.

[0003] International Publication No. 2017 / 175289

[0004] When wearing absorbent articles such as diapers, sweat and moisture tend to accumulate in the wearer's back and buttocks (gluteal cleft), which can easily cause skin problems. To enhance breathability, some absorbent articles, such as those described in Patent Document 1, have through-holes on both sides of the waistband. However, the through-holes on both sides of the waistband do not extend to the gluteal cleft, making it difficult to eliminate sweat accumulation in the gluteal cleft. Furthermore, even with diapers that have multiple small holes on the back or through-holes on the crotch side of the waistband, the small holes similarly make it difficult to prevent sweat from accumulating in the back or gluteal cleft, and through-holes on the crotch side may be more susceptible to leakage. Furthermore, if the diaper has openings on the back, there is a risk of leakage from the openings during wear.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a pants-type disposable diaper that is highly breathable, prevents sweat from accumulating on the wearer's back or buttocks, and is also less likely to leak.

[0006] The main invention for achieving the above object is a pants-type disposable diaper having an absorbent main body having an absorbent core in a vertical direction, a horizontal direction, and a thickness direction that are perpendicular to each other, a ventral waist portion, a back waist portion, and multiple waist elastic members that are stretchable in the horizontal direction and arranged at least in the back waist portion at intervals in the vertical direction, wherein the back waist portion has a skin-side sheet and a non-skin-side sheet that is arranged on the non-skin-side side of the skin-side sheet, the waist elastic members are arranged between the skin-side sheet and the non-skin-side sheet, the back waist portion has an opening that penetrates the skin-side sheet and the non-skin-side sheet in the thickness direction, the opening overlaps with the absorbent core in the horizontal direction and is located above the absorbent core in the vertical direction, the opening overlaps with at least one of the waist elastic members in the vertical direction, and the waist elastic members are discontinuous within the opening in the horizontal direction. Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0007] According to the present invention, it is possible to provide a pants-type disposable diaper which is highly breathable, prevents sweat from accumulating on the back or buttocks of the wearer, and is also less susceptible to leakage.

[0008] 4A is a schematic perspective view of the pants-type disposable diaper 1 as seen from the back side. It is a schematic plan view of the diaper 1 in an unfolded and stretched state as seen from the skin side. It is a schematic cross-sectional view taken along line A-A in FIG. 2. FIG. 4A is a diagram showing a portion of the band-shaped back waistline member 300 in a stretched state before the slit S (opening 50) is formed. FIG. 4B is a diagram showing a portion of the band-shaped back waistline member 300 in a stretched state after the slit S (opening 50) is formed. FIG. 4C is a diagram showing a portion of the back waistline portion 30 in a worn state. It is a partial enlarged view of the back waistline portion 30 in a worn state. It is a partial enlarged view of the back waistline portion 30 in FIG. 2 for explaining the opening 50. FIG. 6B is a diagram showing a modified arrangement of the first opening 50a and the second opening 50b. FIG. 6C is a diagram illustrating waistline elastic members 33 colored in a predetermined color and arranged in the back waistline portion 30. 7A is a schematic plan view showing the back waist portion 30 in FIG. 2 and illustrating the back three-dimensional gathers 30RG. 7B is a diagram illustrating the back three-dimensional gathers 30RG by cutting the diaper 1 at the line B-B in FIG. 7A. 7C is a schematic cross-sectional view of the diaper 1 in the pants-type state, cut at the center in the left-right direction. 7D is a schematic perspective view and a schematic cross-sectional view showing a modified example in which the back waist portion 30 has an alternative sheet member 70. 7E is a diagram illustrating the opening 50 as viewed from the non-skin side when the modified diaper 1 is worn. 7F is a diagram illustrating a first modified example of an alternative sheet member 70 arranged in the back waist portion 30. 7G is a diagram illustrating a second modified example of an alternative sheet member 70 arranged in the back waist portion 30. 7H is a diagram illustrating a third modified example of an alternative sheet member 70 arranged in the back waist portion 30.

[0009] At least the following matters will become clear from the description of this specification and the accompanying drawings. Aspect 1 is a pants-type disposable diaper having a vertical direction, a horizontal direction, and a thickness direction that are perpendicular to one another, and comprising an absorbent main body having an absorbent core, a ventral waist portion, a back waist portion, and a plurality of waist elastic members that are stretchable in the horizontal direction and are arranged at least in the back waist portion at intervals in the vertical direction, wherein the back waist portion has a skin-side sheet and a non-skin-side sheet that is arranged on the non-skin-side side of the skin-side sheet, the waist elastic members are arranged between the skin-side sheet and the non-skin-side sheet, the back waist portion has an opening that penetrates the skin-side sheet and the non-skin-side sheet in the thickness direction, the opening overlaps with the absorbent core in the horizontal direction and is located above the absorbent core in the vertical direction, the opening overlaps with at least one of the waist elastic members in the vertical direction, and the waist elastic members are discontinuous within the opening in the horizontal direction.

[0010] In the pants-type disposable diaper of Aspect 1, the opening overlaps the waist elastic member in the vertical direction, and thus the opening opens when the elastic member contracts, improving breathability. The presence of such an opening in the portion of the back waist portion that overlaps the absorbent core in the horizontal direction allows air to flow more easily to the back and gluteal cleft, where moisture tends to accumulate, and prevents sweat from accumulating. Furthermore, the location of the opening above the absorbent core also reduces the risk of leakage of excrement.

[0011] Aspect 2 is a pants-type disposable diaper having a vertical direction, a horizontal direction, and a thickness direction that are orthogonal to one another, and comprising an absorbent main body having an absorbent core, a ventral waist portion, a back waist portion, and waist elastic members that are stretchable in the horizontal direction and are arranged at least in the back waist portion at intervals in the vertical direction, the back waist portion having a skin-side sheet and a non-skin-side sheet that is provided on the non-skin-side side of the skin-side sheet, the waist elastic members being provided between the skin-side sheet and the non-skin-side sheet, the back waist portion having openings that penetrate the skin-side sheet and the non-skin-side sheet in the thickness direction, the opening overlaps with at least one of the waist elastic members in the vertical direction, the waist elastic members are discontinuous within the opening in the left-right direction, the back waist portion has a back three-dimensional gather at the top end of the absorbent main body in the vertical direction, the back three-dimensional gather has a base end that cannot stand up, and an upright portion that can stand up toward the skin in the thickness direction with the base end as a fulcrum by a three-dimensional gather elastic member that contracts in the left-right direction, the upright portion is located lower than the base end in the vertical direction, and the base end is located lower than the opening in the vertical direction.

[0012] In the pants-type disposable diaper of aspect 2, the upright portion of the back three-dimensional gathers, which is the free portion, is located below the base end (toward the crotch), i.e., it extends from the base end toward the crotch side and stands up when worn, thereby preventing urine, feces, etc. excreted in the crotch area from spreading to the back waist area. Therefore, even if there is an opening in the back waist area, the provision of such back three-dimensional gathers below the opening reduces concerns about leakage.

[0013] Aspect 3 is the underpants-type disposable diaper according to aspect 1 or 2, wherein the length of the opening in the vertical direction is less than 15 mm.

[0014] In the pants-type disposable diaper of aspect 3, the vertical length of the opening is less than 15 mm, which makes it difficult for the user's fingers to enter the opening when wearing the diaper, thereby reducing the risk of the diaper tearing and reducing its fit due to fingers entering the opening.

[0015] Aspect 4 is the underpants-type disposable diaper according to any one of Aspects 1 to 3, wherein, in the stretched state, the opening is a slit extending in the up-down direction.

[0016] In the pants-type disposable diaper of aspect 4, if the opening is a slit extending in the left-right direction, the edges of the slit may be easily torn when the diaper is pulled up during wear, resulting in a poor fit and increased risk of leakage. In this regard, by providing the opening as a slit extending in the up-down direction, which is the direction in which the diaper is pulled up, such risk can be prevented.

[0017] Aspect 5 is the pants-type disposable diaper according to any one of Aspects 1 to 3, wherein in the stretched state, the opening is a cutout formed by cutting out a predetermined area.

[0018] According to the pants-type disposable diaper of aspect 5, the opening is easier to open, improving breathability. As a result, the diaper is less likely to become stuffy.

[0019] Aspect 6 is a pants-type disposable diaper according to any one of Aspects 1 to 5, in which when one of the waist elastic members overlapping the opening in the vertical direction is an overlapping waist elastic member, in a stretched state, the vertical length of the opening is longer than the vertical distance between the overlapping waist elastic member and another waist elastic member adjacent to the overlapping waist elastic member in the vertical direction.

[0020] In the pants-type disposable diaper of aspect 6, the vertical length of the opening is longer than the distance between adjacent waist elastic members in the vertical direction, so that at least one waist elastic member is discontinuous within the opening. Contraction of the overlapping waist elastic members opens the opening in the left-right direction, making it more resistant to stuffiness.

[0021] Aspect 7 is the pants-type disposable diaper according to Aspect 6, wherein when the upper waist elastic member adjacent to the overlapping waist elastic member in the vertical direction is an upper waist elastic member and the lower waist elastic member is a lower waist elastic member, in a stretched state, the vertical length of the opening is longer than the vertical length from the upper waist elastic member to the lower waist elastic member.

[0022] In the pants-type disposable diaper of aspect 7, the length of the opening is longer than the distance between the overlapping waist elastic member that overlaps the opening in the vertical direction and each of the vertically adjacent elastic members (the upper waist elastic member and the lower waist elastic member) (i.e., two spaces between adjacent elastic members), so that at least two waist elastic members are discontinuous within the opening, which allows the opening to open wider, improving breathability and preventing stuffiness.

[0023] Aspect 8 is a pants-type disposable diaper according to any one of Aspects 1 to 6, wherein the magnitude of the force required to stretch the waist elastic members that overlap the opening in the up-down direction by a unit length in the left-right direction is greater than the magnitude of the force required to stretch the waist elastic members that do not overlap the opening in the up-down direction by a unit length in the left-right direction.

[0024] According to the pants-type disposable diaper of aspect 8, the waist elastic members that overlap the opening in the vertical direction have a strong tightening force, so even if an opening is provided, the tightening force in the horizontal direction is unlikely to weaken, and the fit can be maintained.

[0025] Aspect 9 is a pants-type disposable diaper according to any one of Aspects 1 to 8, in which the opening overlaps with at least two of the waist elastic members that are adjacent in the vertical direction, and in a stretched state, the vertical distance between the two waist elastic members that are adjacent in the vertical direction is shorter than the vertical distance between two waist elastic members that are adjacent in the vertical direction and do not overlap with the opening in the vertical direction.

[0026] In the pants-type disposable diaper of Aspect 9, the greater the number of waist elastic members that overlap the opening in the vertical direction, the weaker the tightening force in the left-right direction at the portion where the opening is provided. However, by shortening the intervals between the elastic members that overlap the opening in the vertical direction, the tightening force can be increased and a good fit can be maintained. Furthermore, by increasing the number of elastic members that overlap the opening in the vertical direction, the opening is pulled more in the left-right direction, making it easier to open the opening.

[0027] A tenth aspect of the present invention is the underpants-type disposable diaper according to the ninth aspect, wherein a plurality of the openings overlapping the two adjacent waist elastic members in the up-down direction are provided at intervals in the left-right direction.

[0028] According to the pants-type disposable diaper of aspect 10, the tightening force tends to be high in the areas that overlap the above-mentioned openings in the vertical direction and where the spacing between the elastic members is short, but by having multiple openings, the pulling force of the elastic members can be reduced, thereby achieving a better fit without over-tightening.

[0029] Aspect 11 is a pants-type disposable diaper according to any one of Aspects 1 to 10, in which the opening is provided in the lower region when the distance between the upper end of the absorbent main body and the upper end of the back waist portion is divided into two in the vertical direction.

[0030] According to the pants-type disposable diaper of aspect 11, the above-mentioned lower region is close to the wearer's intergluteal cleft, and the presence of openings in such region facilitates ventilation, thereby reducing the accumulation of sweat in the intergluteal cleft.

[0031] Aspect 12 is a pants-type disposable diaper according to any one of Aspects 1 to 11, in which at least two openings are provided at a distance in the left-right direction, and when the opening on one side in the left-right direction is defined as a first opening and the opening on the other side in the left-right direction is defined as a second opening, in a stretched state, the distance in the left-right direction from the upper end of the first opening to the upper end of the second opening is shorter than the length of the openings in the up-down direction, and the first opening and the second opening have an overlapping portion in the up-down direction, or the first opening and the second opening are provided at a distance in the up-down direction, and the distance from the lower end of the upper opening of the first opening and the second opening to the upper end of the lower opening is shorter than the length of the openings in the up-down direction.

[0032] According to the pants-type disposable diaper of Aspect 12, even if one opening is small, the close proximity of at least two openings makes it easy to see. Furthermore, since each opening is small, it is difficult for a user to insert their fingers, reducing the risk of tearing through the opening.

[0033] Aspect 13 is a pants-type disposable diaper according to Aspect 12, wherein the rear waist portion has a group of openings including the first opening and the second opening, and the plurality of groups of openings are arranged at intervals in the left-right direction, and in a stretched state, the left-right distance between two adjacent groups of openings in the left-right direction is longer than the vertical length of the openings.

[0034] According to the pants-type disposable diaper of Aspect 13, the provision of a plurality of opening groups improves the visibility of the openings and further enhances breathability. If the spacing between the opening groups is too narrow, there will be many discontinuous portions of the waist elastic member, which may weaken the tightening force. Therefore, by not making the spacing between the opening groups too close, a decrease in the tightening force can be avoided.

[0035] Aspect 14 is the pants-type disposable diaper according to Aspect 12 or 13, wherein in a stretched state, the first opening and the second opening are spaced apart in the vertical direction by at least half the vertical length of the openings.

[0036] In the pants-type disposable diaper of aspect 14, the distance between the first opening and the second opening in the left-right direction is narrow, and if the distance between the two openings in the up-down direction is also narrow, there is a risk that each opening will be difficult to open properly. However, by spacing the openings apart in the up-down direction, this difficulty in opening can be avoided.

[0037] Aspect 15 is the underpants-type disposable diaper according to any one of Aspects 1 to 14, wherein a plurality of the openings are provided, and the plurality of openings do not overlap each other in the left-right direction.

[0038] In the pants-type disposable diaper of aspect 15, if multiple openings overlap in the left-right direction, tears may occur between the openings when the diaper is pulled up during putting on, resulting in a poor fit. However, since the openings do not overlap in the left-right direction, tears are less likely to occur.

[0039] Aspect 16 is a pants-type disposable diaper according to any one of aspects 1 to 15, in which a post-treatment tape is provided on the non-skin side of the back waist portion to be used when disposing of the pants-type disposable diaper after use, and the opening does not overlap with the post-treatment tape in the left-right direction.

[0040] According to the pants-type disposable diaper of aspect 16, the opening and the post-treatment tape do not overlap, making it easier to fasten the post-treatment tape.

[0041] Aspect 17 is the underpants-type disposable diaper according to aspect 2, wherein the openings are provided on both outer sides of the absorbent core in the left-right direction.

[0042] According to the pants-type disposable diaper of Aspect 17, since openings are provided not only in the portion overlapping the absorbent core in the left-right direction but also on both left-right outer sides of the absorbent core, the regions where the openings are located along the left-right direction have low rigidity and are easily deformed. As a result, the movement of the upper part of the back waistband and the movement of the back three-dimensional gathers are separated, allowing the back three-dimensional gathers to easily follow the movement of the buttocks and are less likely to slip.

[0043] Aspect 18 is a pants-type disposable diaper according to Aspect 2 or 17, wherein the lower end of the base end of the back-side upright gather in the vertical direction is located lower than the upper end of the absorbent main body in the vertical direction.

[0044] According to the pants-type disposable diaper of aspect 18, the absorbent body is present below the lower end of the base end (crotch side), so that the discharged liquid blocked by the back three-dimensional gathers is easily absorbed and is less likely to leak.

[0045] Aspect 19 is a pants-type disposable diaper according to any one of Aspects 2, 17, and 18, in which the ventral waist portion and the rear waist portion are joined at both left-right sides by a pair of side joints, both left-right sides of the rear three-dimensional gathers are joined by the pair of side joints, and the rear three-dimensional gathers are not fixed between one end and the other end of the pair of side joints in the left-right direction.

[0046] In the pants-type disposable diaper of Aspect 19, the back-side three-dimensional gathers are not fixed between the pair of side joints, so that the back-side three-dimensional gathers can move freely between the pair of side joints, making it easier for the standing portions to stand up. When the standing portions stand up so that they firmly contact the skin, a pocket-like space is formed, making it less likely for leakage to occur.

[0047] Aspect 20 is a pants-type disposable diaper according to any one of Aspects 2 and 17 to 19, wherein the magnitude of the force required to stretch the three-dimensional gathered elastic member by a unit length in the left-right direction is smaller than the magnitude of the force required to stretch the waist elastic member that overlaps the opening in the up-down direction by a unit length in the left-right direction.

[0048] According to the pants-type disposable diaper of aspect 20, the force required to stretch the three-dimensional gather elastic member arranged in the back three-dimensional gather is small, so that the back three-dimensional gather is easily deformed and easily fits the buttocks of the wearer.

[0049] Aspect 21 is the underpants-type disposable diaper according to any one of Aspects 1 to 20, wherein the opening does not penetrate the back waist portion in the thickness direction.

[0050] According to the pants-type disposable diaper of aspect 21, although an opening is provided, the opening is not pierced in the back waist portion, thereby reducing the anxiety of leakage.

[0051] Aspect 22 is a pants-type disposable diaper according to any one of aspects 1 to 21, in which the skin-side sheet and the non-skin-side sheet have separate sheet members, and the separate sheet members cover the opening from the skin side.

[0052] According to the pants-type disposable diaper of Aspect 22, the risk of leakage from the opening can be reduced by covering the opening from the skin side with another sheet member.

[0053] Aspect 23 is the underpants-type disposable diaper according to aspect 22, wherein the separate sheet member is a sweat-absorbing sheet.

[0054] According to the pants-type disposable diaper of aspect 23, sweat absorbed by the sweat-absorbent sheet evaporates from the openings located closer to the skin than the sweat-absorbent sheet, so the diaper is less likely to become stuffy.

[0055] Aspect 24 is the underpants-type disposable diaper according to aspect 22, wherein the separate sheet member is a nonwoven fabric having openings smaller than the openings.

[0056] According to the pants-type disposable diaper of aspect 24, the openings of the nonwoven fabric are not blocked at the opening portion, so that the diaper is less likely to become stuffy. Furthermore, when the pants-type disposable diaper is viewed from the non-skin side, not only the nonwoven fabric but also the small openings in the nonwoven fabric are visible through the openings, which confirms the good breathability and gives the impression of being cool.

[0057] Aspect 25 is a pants-type disposable diaper according to any one of Aspects 1 to 24, wherein the lower end of the opening in the vertical direction is located lower than the upper end of the absorbent body in the vertical direction in the ventral waist region.

[0058] According to the pants-type disposable diaper of aspect 25, the back waist portion has an opening located near the intergluteal cleft to prevent stuffiness in the back and intergluteal cleft, while the ventral waist portion has an absorbent body positioned all the way up to prevent urine leakage.

[0059] Embodiments Hereinafter, an embodiment of the present invention will be described using a pants-type disposable diaper 1 for infants (hereinafter also referred to as "diaper 1") as an example of a pants-type disposable diaper for infants. However, the pants-type absorbent article of the present invention is not limited to disposable diapers for infants, and can also be used as a disposable diaper for adults.

[0060] ===Basic Configuration of Pants-Type Disposable Diaper 1=== Fig. 1 is a schematic perspective view of the pants-type disposable diaper 1 (diaper 1) as seen from the back side. Fig. 2 is a schematic plan view of the diaper 1 in an unfolded and stretched state as seen from the skin side. Fig. 3 is a schematic cross-sectional view taken along line A-A in Fig. 2.

[0061] 1, the diaper 1 has a vertical direction, a horizontal direction, and a front-to-back direction that intersect with one another, and is formed with a waist opening BH and a pair of leg openings LH. In the vertical direction, the waist opening BH side is referred to as the upper side, and the crotch side is referred to as the lower side. As shown in FIG. 3, the direction in which the materials constituting the diaper 1 are layered is referred to as the thickness direction, and the side that comes into contact with the wearer in the thickness direction is referred to as the skin side, and the side that does not come into contact with the wearer is referred to as the non-skin side.

[0062] The unfolded state of the diaper 1 refers to a state in which the pair of seams 5 on both sides of the diaper 1 are separated and the diaper 1 is opened and unfolded in a flat plane. The stretched state of the diaper 1 shown in Fig. 2 refers to a state in which the elastic members of the diaper 1 are stretched to an extent that wrinkles in the diaper 1 are no longer visible. Specifically, this refers to a state in which the dimensions of each component constituting the diaper 1 are equal to or close to the dimensions of that component alone (i.e., the dimensions of the elastic members in a non-stretchable state), and also refers to a state in which the elastic members between adjacent openings 50 in the lateral direction, as described below, are stretched to a non-stretchable state.

[0063] The diaper 1 of this embodiment is a so-called three-piece pants-type diaper, and includes an absorbent main body 10, a ventral waist section 20, and a dorsal waist section 30. The ventral waist section 20 is a section that is placed against the wearer's ventral region, and the dorsal waist section 30 is a section that is placed against the wearer's posterior region.

[0064] In the diaper 1 in the unfolded state shown in Fig. 2, the ventral waist portion 20 and the rear waist portion 30 are arranged so that their longitudinal directions are aligned with the left-right direction of the diaper 1. One longitudinal end of the absorbent main body 10 is arranged in the center of the ventral waist portion 20 in the left-right direction, and the other longitudinal end of the absorbent main body 10 is arranged in the center of the rear waist portion 30 in the left-right direction.

[0065] Then, the absorbent body 10 is folded in half approximately at the center of the longitudinal direction so that the longitudinal direction of the absorbent body 10 is aligned with the vertical direction of the diaper 1, and the both side end portions 20se, 20se of the ventral waist portion 20 and the both side end portions 30se, 30se of the dorsal waist portion 30 in the left-right direction of the diaper 1 are joined by heat welding, ultrasonic welding, etc., to form a pair of side joint portions 5, thereby resulting in the pants-type diaper 1 as shown in Figure 1.

[0066] As shown in Figure 3, the absorbent body 10 comprises an absorbent core 11 that absorbs excrement, a liquid-permeable top sheet 12 arranged closer to the skin than the absorbent core 11, a liquid-impermeable back sheet 13 arranged closer to the skin than the absorbent core 11, and an outer sheet 14 arranged closer to the skin than the back sheet 13, each of which is bonded together with an adhesive or the like.

[0067] The absorbent core 11 can be, for example, a liquid-absorbent fiber such as pulp containing superabsorbent polymer (SAP) molded into a predetermined shape. The absorbent core 11 may be covered with a core wrap sheet (not shown) such as liquid-permeable tissue paper or nonwoven fabric. The top sheet 12 is formed of, for example, a nonwoven fabric such as an air-through nonwoven fabric or a spunbond nonwoven fabric. The back sheet 13 is, for example, a liquid-impermeable and breathable film such as polyethylene or polypropylene. The exterior sheet 14 is formed of, for example, the same nonwoven fabric as the top sheet 12.

[0068] The absorbent body 10 also has leg elastic members 15 (e.g., rubber threads) on both lateral sides thereof that are stretchable in the longitudinal direction (vertical direction), thereby allowing the diaper 1 to fit snugly around the legs of the wearer.

[0069] The absorbent body 10 also has leakage preventing walls 16 that can stand up on the skin side on both left and right sides. For example, the leakage preventing walls 16 are formed by folding both left and right sides of the exterior sheet 14 inward in the left and right direction so that they are positioned on the skin side of the top sheet 12, and providing the folded-back portions with leakage preventing wall elastic members 16r (e.g., rubber threads) that stretch in the longitudinal direction.

[0070] As shown in Fig. 3, the ventral waistband 20 and the back waistband 30 each have a skin-side sheet 21, 31 and a non-skin-side sheet 22, 32 made of a soft nonwoven fabric or the like. Also, as shown in Fig. 3, the upper part of the ventral waistband 20 has the non-skin-side sheet 22 folded downward from the upper end of the ventral waistband 20 toward the skin side to form a folded-back portion 22f, in order to improve feel and durability. Similarly, the upper part of the back waistband 30 has the non-skin-side sheet 32 ​​folded downward from the upper end of the back waistband 30 toward the skin side to form a folded-back portion 32f. The back waistband 30 has a back-side three-dimensional gather 30RG formed by the lower part of the folded-back portion 32f. Details of the back-side three-dimensional gather 30RG will be described later.

[0071] Furthermore, the back-side waistline portion 30 is provided with a plurality of openings 50 each having a predetermined length in the up-down direction and penetrating from the skin side to the non-skin side in the thickness direction through each of the skin side sheets 31 and non-skin side sheets 32 that form the back-side waistline portion 30. Details of the openings 50 will be described later.

[0072] A plurality of waistline elastic members 23 (33), such as rubber threads, that stretch in the left-right direction are arranged between the skin-side sheet 21 (31) and the non-skin-side sheet 22 (32) of the ventral waistline portion 20 (dorsal waistline portion 30), which is a waistline portion. The waistline elastic members 23 (33) are joined and fixed to the skin-side sheet 21 (31) and the non-skin-side sheet 22 (32) in a stretched state in the left-right direction using an adhesive or ultrasonic bonding. Specifically, the plurality of waistline elastic members 23 (33), 23 (33)... to which adhesive is applied are arranged between the skin-side sheet 21 (31) and the non-skin-side sheet 22 (32) in a stretched state in the left-right direction, so that the plurality of waistline elastic members 23 (33), 23 (33)... are joined and fixed to the skin-side sheet 21 (31) and the non-skin-side sheet 22 (32) in a stretched state. The multiple waist elastic members 23, 33 are arranged side by side at intervals in the vertical direction in the ventral waist portion 20 and the dorsal waist portion 30. Therefore, the ventral waist portion 20 and the dorsal waist portion 30 are stretchable in the horizontal direction and fit the waist of the wearer.

[0073] The waist elastic members 23 (33) are made discontinuous in a region that overlaps with the absorbent core 11 near the center in the left-right direction, so that they are not stretchable. This prevents the absorbent core 11 from contracting in the left-right direction, making it easier to maintain the absorbent core 11 in a generally flat state, thereby preventing leakage of excrement, etc.

[0074] Although the basic configuration of the diaper 1 has been described above, the configuration of the diaper 1 is not limited to the above. For example, the diaper 1 may be a two-piece type diaper, in which the ventral waistband 20 and the dorsal waistband 30 are formed from a single continuous member, or an outer member may be provided connecting the ventral waistband 20 and the dorsal waistband 30. Furthermore, the leg-hole elastic members 15 may be sheet-like elastic members (stretchable film or stretchable nonwoven fabric) instead of rubber thread. Furthermore, a sheet-like elastic member (stretchable film or stretchable nonwoven fabric) may be provided in the dorsal waistband 30 above the position where the opening 50 is provided.

[0075] <Regarding the Opening 50> First, the formation of the opening 50 in this embodiment will be described. The opening 50 provided in the back waistline portion 30 is formed during the manufacturing process of the back waistline portion 30 in the manufacture of the diaper 1. In the back waistline portion 30, the strip-shaped back waistline member 300, which includes, in order from the skin side, a strip-shaped non-skin-side sheet folded-back portion 320f formed by folding back the strip-shaped non-skin-side sheet 320, a strip-shaped skin-side sheet (not shown), a continuous waistline elastic member 330, and a strip-shaped non-skin-side sheet (not shown), is separated into individual back waistline portions 30.

[0076] Fig. 4A is a diagram showing a portion of the band-shaped back waistline member 300 in a stretched state before the slit S (opening 50) is formed. Fig. 4B is a diagram showing a portion of the band-shaped back waistline member 300 in a stretched state after the slit S (opening 50) is formed. Fig. 4C is a diagram showing a portion of the back waistline portion 30 in a worn state. Figs. 4A, 4B, and 4C are each views as seen from the skin side.

[0077] Figure 4A shows the state of the belt-shaped back waistband member 300 before the slit S is formed, in which the belt-shaped non-skin side sheet folded portion 320f, the belt-shaped skin side sheet, and the belt-shaped non-skin side sheet have been stretched until wrinkles are almost eliminated.

[0078] Next, as shown in Fig. 4B, a linear slit S is formed in the stretched strip-shaped back waistband member 300 along the vertical direction so as to cross some of the continuous waistband elastic members 330. The slit S is formed by cutting the two continuous waistband elastic members 330 together with the strip-shaped skin side sheet and the strip-shaped non-skin side sheet using a predetermined blade. Fig. 4B shows the moment when the slit S is formed by cutting. The slit S is then formed into an opening 50 as shown in Fig. 4C by the continuous waistband elastic member 330.

[0079] FIG. 4C shows a portion of the back waist portion 30 when the diaper 1 is being worn by a wearer. The opening 50 in the back waist portion 30 when the diaper 1 is being worn opens on both the left and right sides, forming a generally hexagonal shape. This is because, as shown in FIG. 4C , the waist elastic members 33 contract from their elongated state, pulling the periphery of the opening 50 in the left and right directions. This allows the opening 50 to open more widely when the diaper 1 is worn, thereby further improving the breathability of the diaper 1. By allowing each opening 50 to open more widely, the breathability of the diaper 1 can be ensured with a smaller number of openings 50. Furthermore, because the contracted waist elastic members 33 allow the openings 50 to open in the left and right directions even before the diaper 1 is worn, parents or guardians putting the diaper 1 on a wearer, such as an infant, can visually recognize the openings 50 and recognize the improved breathability.

[0080] As described above, the shape of the opening 50 in this embodiment is approximately hexagonal, but strictly speaking it is not a hexagon, but a shape in which each vertex can be recognized, and most of its contours are curved rather than straight. Furthermore, if the number of cuts in the continuous waistband elastic member 330 in the process of forming the slits S changes, the number of elastic members that pull the periphery of the opening 50 to the left and right when opening the opening will also change, and the shape of the opening will also change.

[0081] The slits S may be formed after the absorbent body 10 is placed in the back waistline portion 30, or the slits S may be formed in the back waistline portion 30 and then the absorbent body 10 is placed therein.

[0082] Next, the configuration of the openings 50 will be described. Fig. 5 is a partial enlarged view of the back waistline portion 30 in a worn state. As shown in Figs. 2 and 5, a plurality of openings 50 are provided in the back waistline portion 30 so as to be located above the absorbent core 11 in the up-down direction. More specifically, a plurality of openings 50 are provided in the back waistline portion 30 so as to be located above the absorbent main body 10 in the up-down direction, and no openings 50 are provided in an area overlapping with the absorbent main body 10 in a plan view. In the left-right direction, the openings 50 are also provided at positions overlapping with the absorbent core 11 and outside the absorbent core 11, but it is sufficient that the openings are provided so as to overlap at least the absorbent core 11.

[0083] Furthermore, each opening 50 in this embodiment overlaps with at least two waist elastic members 33 in the vertical direction, and the waist elastic members 33 are discontinuous in the left-right direction within the opening 50. Specifically, no cut waist elastic members 33 are provided inside each opening 50, and the cut waist elastic members 33 are discontinuous in the left-right direction within the opening 50. This is because, when the opening 50 is formed, the waist elastic members 33 provided at the formation position of the opening 50 are cut together. Therefore, for example, as shown in FIG. 5, the waist elastic members 33t １ The waist elastic members 33t are continuous from the outer side of the opening 50i in the left-right direction to the outer side of the opening 50j in the left-right direction, and are not provided inside the openings 50i and 50j. １ The waist elastic members 33t extend from the outer side of the opening 50j in the left-right direction to the outer side of the opening 50m in the left-right direction, and also extend from the outer side of the opening 50m in the left-right direction to the outer side of the opening 50n in the left-right direction, and are not provided inside the openings 50m and 50n. ２ Also, the waist elastic member 33t １ Similarly, the waist elastic member 33t has the same configuration as that of the waist elastic member 33t.３ and 33t ４ The opening 50h is continuous from the outer side in the left-right direction to the outer side in the left-right direction of the opening 50k, and is not provided inside the openings 50h and 50k.

[0084] Since the opening 50 overlaps the waist elastic member 33 in the vertical direction, contraction of the waist elastic member 33 opens the opening 50, improving breathability. While the diaper 1 is worn, sweat and moisture tend to accumulate in the wearer's back, gluteal cleft, and other areas. In this regard, in the present embodiment, the opening 50 is located in a portion of the back waist portion 30 that laterally overlaps with the absorbent core 11, allowing air to flow more easily to the back and gluteal cleft, where moisture tends to accumulate, thereby preventing sweat from accumulating. Furthermore, if the opening 50 is located on the lower vertical side (crotch side) of the back waist portion 30, this may lead to leakage. However, by locating the opening 50 above the absorbent core 11 as in the present embodiment, the risk of excrement leaking through the opening 50 is reduced.

[0085] In this embodiment, the opening 50 overlaps with at least two waist elastic members 33 in the vertical direction, but this is not limited to this and it may overlap with at least one waist elastic member 33, or it may overlap with three or more waist elastic members 33.

[0086] Fig. 6A is a partially enlarged view of the back waist portion 30 of Fig. 2, illustrating the opening 50. As shown in Fig. 6A, in a stretched state, the opening 50 is a slit extending in the vertical direction. The slit is preferably formed at an angle of approximately 90 degrees relative to the waist elastic members 33, but may also be formed at an angle in the range of approximately 70 to 110 degrees relative to the waist elastic members 33. If the opening 50 were a slit extending in the horizontal direction, tears would easily occur at the ends of the slit when the diaper 1 is pulled up during wear, which could result in a poor fit and increased leakage. In this regard, by forming the opening 50 in a slit extending in the vertical direction, which is the direction in which the diaper 1 is pulled up, such a risk can be prevented.

[0087] Furthermore, the vertical length L1 of the opening 50 is preferably less than 15 mm. More preferably, the vertical length L1 of the opening 50 is greater than 5 mm and less than 15 mm. If the vertical length L1 of the opening 50 is less than 15 mm, when the opening 50 is open as shown in Fig. 5, it becomes difficult to insert a finger into the opening 50 when wearing the diaper 1, thereby reducing the risk of the diaper 1 tearing due to insertion of a finger into the opening 50 and a deterioration in fit. Furthermore, if the opening 50 is too small, breathability will be reduced, so by making the vertical length L1 greater than 5 mm, it becomes easier to achieve improved breathability.

[0088] In this embodiment, the opening 50 is a vertical slit, but the present invention is not limited to this. The opening 50 may be a cutout formed by cutting out a predetermined area in a stretched state. Forming the opening 50 by a cutout makes the opening 50 easier to open, improving breathability. This makes the diaper 1 less likely to become stuffy. Furthermore, the aesthetic appeal of the diaper 1 can be improved by forming the cutout in a desired shape, such as a circle, star, or heart.

[0089] Next, the relationship between the waist elastic members 33 and the opening 50 will be further described. As shown in FIG. 6A, one of the waist elastic members 33 overlapping the opening 50 in the vertical direction is designated as a waist elastic member (overlapping waist elastic member) 33t. １ In this case, in the stretched state, the vertical length L1 of the opening 50 is １ and another waist elastic member 33t ２ The vertical distance L1 is longer than the vertical distance L2 between the waist elastic members (33t １ , 33t ２ Since the vertical length L1 of the opening 50 is longer than the distance between the overlapping waist elastic members 33t and the waist elastic members 33t, at least one of the waist elastic members 33t may be discontinuous within the opening 50. As a result, when the diaper 1 is worn, the overlapping waist elastic members 33t may be discontinuous. １5B, the opening 50 opens in the left-right direction, and the diaper 1 becomes less likely to become stuffy. １ and the waist elastic member 33t below it. ２ However, for example, the waist elastic member 33t １ The gap between the upper and lower waist elastic members 33t may be equal to the gap between the upper and lower waist elastic members 33t. In addition, the gap between the upper and lower waist elastic members 33t may be equal to the gap between the upper and lower waist elastic members 33t. １ It is desirable that the waist elastic members 33 are arranged so that the vertical distance between the first elastic member 33 and the other waist elastic members 33 is longer than the vertical distance L2.

[0090] Furthermore, the above-mentioned overlapping waist elastic member 33t １ The upper waist elastic member 33 adjacent to the upper waist elastic member 33 in the vertical direction is called the upper waist elastic member 33t. ３ The lower waist elastic member 33 is the lower waist elastic member 33t ２ In this case, in the stretched state, the length L1 of the opening 50 in the vertical direction is ３ From the lower waist elastic member 33t ２ It is preferable that the length L1 is longer than the vertical length L3 from the overlapped waistline elastic member 33t to the overlapped waistline elastic member 33t (L1>L3). １ and the waist elastic members 33 (upper waist elastic members 33t) adjacent to each other in the vertical direction. ３ and the lower waist elastic member 33t ２ The length L3 between the adjacent waist elastic members 33 in the vertical direction means two intervals between adjacent waist elastic members 33 in the vertical direction, and since the length L1 of the opening 50 in the vertical direction is longer than the length L3, at least two waist elastic members 33 are discontinuous within the opening 50. This allows the opening 50 to open wider, improving breathability and making the diaper 1 less likely to become stuffy.

[0091] Furthermore, in this embodiment, the magnitude of the force required to stretch the waist elastic members 33t that overlap the opening 50 in the vertical direction by a unit length in the left-right direction is greater than the magnitude of the force required to stretch the waist elastic members 33 that do not overlap the opening 50 in the vertical direction by a unit length in the left-right direction. In other words, the waist elastic members 33t that are positioned to overlap the opening 50 in the vertical direction have a stronger tightening force in the left-right direction. In this way, because the tightening force of the waist elastic members 33t that overlap the opening 50 is strong, even if the waist elastic members 33t have portions that are discontinuous due to the opening 50, the tightening force in the left-right direction is less likely to weaken, and the fit of the back waistline portion 30 can be maintained.

[0092] As described above, in this embodiment, the openings 50 are arranged between at least two waist elastic members 33t (for example, the waist elastic members 33t) that are adjacent to each other in the vertical direction. １ , 33t ２ ) overlap with the opening 50. However, in the stretched state shown in FIG. 6A , the vertical distance L2 between the two waist elastic members 33t is shorter than the vertical distance L4 between the two waist elastic members 33ca, 33cb that are vertically adjacent but do not overlap the opening 50 (L2<L4). The greater the number of waist elastic members 33 that vertically overlap the opening 50, the weaker the lateral tightening force around the opening 50. However, by shortening the distance L2 between the waist elastic members 33t, 33t that vertically overlap the opening 50, the tightening force can be increased. As a result, the fit of the back waist portion 30 can be maintained. Furthermore, by increasing the number of elastic members 33t that vertically overlap the opening 50, the opening 50 is more easily opened due to the lateral tension.

[0093] In this embodiment, as shown in FIG. 6A, two adjacent waist elastic members 33t in the vertical direction １ , 33t ２ As described above, a plurality of openings 50 overlapping the two waist elastic members 33t are provided at intervals in the left-right direction. １ , 33t ２In the portion where the interval L2 between the waist elastic members 33t is short, the tightening force in the left-right direction tends to increase. However, by providing a plurality of openings 50 spaced apart in the left-right direction, the tightening force in the left-right direction tends to increase. １ , 33t ２ This reduces the pulling force of the waist elastic members 33t, and achieves a better fit without being too tight. １ , 33t ２ By cutting the waist elastic member 33t １ , 33t ２ The pulling force can be adjusted, and while ensuring tightness around the waist, the risk of excessive tightness can be reduced, thereby improving the fit of the diaper 1.

[0094] Preferably, the opening 50 is provided in the lower region when the area from the upper end 10ue of the absorbent main body 10 to the upper end 30ue of the back waistline portion 30 is divided into two in the vertical direction. The lower region when divided into two is close to the gluteal cleft of the wearer, and providing the opening 50 in such a region allows easier ventilation to the gluteal cleft and prevents stuffiness.

[0095] As shown in FIG. 6A , two openings 50 are provided in the back waistband portion 30, spaced apart in the left-right direction. The opening 50 on one side in the left-right direction is designated as the first opening 50a, and the opening 50 on the other side in the left-right direction is designated as the second opening 50b. The first opening 50a and the second opening 50b overlap in the vertical direction, and the horizontal distance L5 from the upper end 50ae of the first opening 50a to the upper end 50be of the second opening 50b is shorter than the vertical length L1 of the opening 50. In other words, the first opening 50a and the second opening 50b are close to each other in the vertical and horizontal directions. This arrangement makes the openings 50 easily visible, even if one opening 50 is small, because at least two openings 50 are close to each other. Furthermore, by not making the openings 50 excessively large, it becomes difficult for a user's fingers to enter the opening 50 during use, reducing the risk of tearing the opening 50.

[0096] Note that the first opening 50a and the second opening 50b do not necessarily have to overlap in the vertical direction. Figure 6B illustrates a modified arrangement of the first opening 50a and the second opening 50b. As shown in Figure 6B, the first opening 50a' and the second opening 50b' are spaced apart in the vertical direction, and the distance L6 from the lower end 50ad of the upper opening (here, the first opening 50a') of the first opening 50a' and the second opening 50b' to the upper end 50be of the lower opening (here, the second opening 50b') is shorter than the vertical length L1 of the opening 50 (see Figure 6A). With this configuration, even if the first opening 50a' and the second opening 50b' are spaced apart in the vertical direction, the openings 50 are close to each other, making them easy to see even if each opening 50 is small.

[0097] 6A , when the opening 50 adjacent to the first opening 50a in the left-right direction and located further to the left (left side) of the first opening 50a is designated as the third opening 50c, the positional relationship between the first opening 50a and the third opening 50c is the same as that between the first opening 50a and the second opening 50b. That is, the second opening 50b and the third opening 50c are formed symmetrically with respect to the first opening 50a. Therefore, the first opening 50a, the second opening 50b, and the third opening 50c are closely spaced to form an opening group 50G. In the back waistband portion 30, a plurality of such opening groups 50G are provided at intervals in the left-right direction. In the stretched state, the left-right distance L7 between two adjacent opening groups 50G is longer than the vertical length L1 of the opening 50.

[0098] Providing a plurality of opening groups 50G can improve the visibility of the openings 50 and also increase breathability. If the distance L7 between adjacent opening groups 50G in the left-right direction is too narrow, there will be many discontinuous portions of the waistline elastic members 33, which may weaken the tightening force of the back waistline portion 30. Therefore, by not making the distance L7 between the opening groups 50G too close, a decrease in the tightening force can be avoided.

[0099] 6A , in the extended state, the first opening 50a and the second opening 50b are separated by a distance R1 in the vertical direction, and this distance R1 is preferably equal to or greater than half the vertical length L1 of the opening 50. As described above, because the left-right distance (L5) between the first opening 50a and the second opening 50b is narrow, if the two openings 50a, 50b are not spaced apart in the vertical direction, each opening 50 may be difficult to open properly. However, by spaced apart in the vertical direction, this difficulty in opening can be avoided.

[0100] In this embodiment, multiple openings 50 are provided, but in the stretched state, the multiple openings 50 do not overlap in the left-right direction ( FIG. 2 ). If the multiple openings 50 overlap in the left-right direction, tears may occur between the overlapping openings 50 when the diaper 1 is pulled up during putting on, resulting in a poor fit. However, the fact that the openings 50 do not overlap in the left-right direction makes tears less likely to occur. Furthermore, a preferred arrangement of the multiple openings 50 is a staggered arrangement.

[0101] 1 and 2, a post-treatment tape 38 is provided on the non-skin side of the back waist portion 30, which is used when disposing of the used pants-type disposable diaper 1. It is desirable that the opening 50 does not overlap with the post-treatment tape 38 in the left-right direction. By ensuring that the opening 50 and the post-treatment tape 38 do not overlap, it becomes easier to fasten the post-treatment tape 38.

[0102] 6C is a diagram illustrating the waist elastic member 33 colored in a predetermined color and arranged in the back waist portion 30. In this embodiment, the waist elastic member 33 (33t) overlapping the opening 50 in the vertical direction is preferably an elastic member colored in a predetermined color. In FIG. 6C, to make the colored waist elastic member 33 easier to understand, the dotted line indicating the colored waist elastic member 33 is shown in bold. The waist elastic member 33 (33t) overlapping the opening 50 in the vertical direction is referred to as the waist elastic member 33t. １ , 33t ２、 33 tons ３、 33 tons ４ and 、The predetermined color is preferably a color different from that of the skin side sheet 31 and the non-skin side sheet 32 ​​sandwiching the waist elastic member 33, so that the waist elastic member 33t is easily visible. １ , 33t ２、 33 tons ３、 33 tons ４ By using a colored elastic member, it becomes easier to focus on the colored portion and to notice the opening 50. This makes it possible to make the opening 50 stand out. In addition, by arranging a colored elastic member in the portion where the opening 50 (slit S) is to be formed during the process of forming the opening 50 (slit S), there is also the advantage that the cutting position can be easily adjusted in manufacturing.

[0103] <Regarding the Back-Side 3D Gathers 30RG> Fig. 7A is a schematic plan view showing the back-side waistline portion 30 in Fig. 2 and illustrating the back-side 3D gathers 30RG, and Fig. 7B is a view illustrating the back-side 3D gathers 30RG by cutting the diaper 1 along line B-B in Fig. 7A . If an opening 50 is provided in the back-side waistline portion 30 as in this embodiment, there is a risk of leakage from the opening 50. In response to this issue, as shown in Figs. 7A and 7B , the back-side waistline portion 30 has a back-side 3D gather 30RG at the top end of the absorbent main body 10 in the vertical direction. The back-side 3D gather 30RG has a base end 30RGb that cannot stand upright and a standing portion 30RGk that can stand upright toward the skin in the thickness direction using the base end 30RGb as a fulcrum by a 3D gather elastic member 30Rs (e.g., rubber thread) that contracts in the left-right direction. In this embodiment, the back three-dimensional gathers 30RG are formed by the folded portion 32f formed by folding back the non-skin side sheet 32, but the back three-dimensional gathers 30RG may also be formed using, for example, a sheet material other than the skin side sheet 31 and the non-skin side sheet 32.

[0104] The base end 30RGb of the back-side three-dimensional gather 30RG extends in the left-right direction and is bonded and fixed to the topsheet 12. The upright portion 30RGk has its end folded back at the folded-back portion 32f toward the skin, and is fitted with a three-dimensional gather elastic member 30Rs that is stretchable in the left-right direction. The upright portion 30RGk is located vertically lower (toward the crotch) than the base end 30RGb. That is, the back-side three-dimensional gather 30RG extends downward (toward the crotch) from the base end 30RGb. As shown in the right diagram of FIG. 7B , when worn, the contraction of the three-dimensional gather elastic member 30Rs causes the upright portion 30RGk to rise from the topsheet 12, forming the back-side three-dimensional gather 30RG. The rising of the upright portion 30RGk prevents urine, feces, etc. excreted in the crotch area from spreading across the back waistband 30. Furthermore, since the base end 30RGb is located vertically lower than the opening 50, even if there is an opening 50 in the back waistline portion 30, the rising portion 30RGk can block the opening, thereby reducing the risk of leakage. Note that in this embodiment, two three-dimensional gather elastic members 30Rs are used, but the number is not limited to this. Furthermore, the back three-dimensional gathers 30RG may be formed using, for example, another stretchable sheet member without using the three-dimensional gather elastic members 30Rs.

[0105] In the diaper 1, the ventral waistband 20 and the back waistband 30 are joined at their left-right sides by a pair of side joins 5, 5, and the back three-dimensional gathers 30RG are also joined at their left-right sides by a pair of side joins 5, 5 ( FIG. 7A ). On the other hand, the back three-dimensional gathers 30RG are not fixed between the left and right ends of the pair of side joins 5, 5. Because the pair of side joins 5, 5 of the back three-dimensional gathers 30RG are not fixed, the pair of side joins 5, 5 can move freely between the pair of side joins 5, 5, allowing the standing portions 30RGk to easily stand up. When the diaper 1 is put on, the standing portions 30RGk flip up, and the ends of the standing portions 30RGk stand up firmly against the skin, forming a pocket-like space and reducing leakage ( right diagram in FIG. 7B ).

[0106] In this embodiment, the openings 50 are located above the absorbent core 11, and are also provided in a portion overlapping the absorbent core 11 in the left-right direction and on both left-right outer sides of the absorbent core 11. Providing the openings 50 not only in the portion overlapping the absorbent core 11 in the left-right direction but also on both left-right outer sides of the absorbent core 11 reduces rigidity and facilitates deformation in the region where the openings 50 are located in the left-right direction. This separates the movement of the upper portion of the back waistband 30 from the movement of the back-side three-dimensional gathers 30RG, allowing the back-side three-dimensional gathers 30RG to more easily follow the movement of the buttocks and less likely to slip. This improves the fit of the diaper 1 around the back and buttocks.

[0107] 7A , the lower end 30RGbe in the vertical direction of the base end 30RGb of the back-side three-dimensional gather 30RG is located below the upper end 10ue in the vertical direction of the absorbent main body 10. In other words, since the absorbent main body 10 is present below (on the crotch side) the lower end 30RGbe of the base end 30RGb, the discharged liquid blocked by the back-side three-dimensional gather 30RG is more easily absorbed and less likely to leak.

[0108] In the diaper 1, the magnitude of the force required to stretch the upright gather elastic member 30Rs by a unit length in the left-right direction is smaller than the magnitude of the force required to stretch the waist elastic member 33t that overlaps the opening 50 by a unit length in the up-down direction. Because the force required to stretch the upright gather elastic member 30Rs arranged in the back-side upright gather 30RG is smaller, the back-side upright gather 30RG is more easily deformed, which makes it easier to fit the buttocks of the wearer.

[0109] Fig. 8 is a schematic cross-sectional view of the diaper 1 in the pants-type state, cut at the center in the left-right direction. As shown in Fig. 8, in the diaper 1 of this embodiment, the lower end 50ed in the vertical direction of the opening 50 is located below the upper end 10ef in the vertical direction of the absorbent body 10 in the ventral waistline portion 20. On the back-side waistline portion 30 side, the opening 50 is provided in a position close to the intergluteal cleft to prevent stuffiness in the back and intergluteal cleft, while on the ventral waistline portion 20 side, the absorbent body 10 is positioned all the way up to prevent urine leakage.

[0110] Fig. 9A is a schematic perspective view and a schematic cross-sectional view showing a modified example in which the back waist portion 30 has a separate sheet member 70, and Fig. 9B is a view illustrating the openings 50 as viewed from the non-skin side when the diaper 1 of the modified example is worn. In the modified example shown in Fig. 9A , the back waist portion 30 of the diaper 1 has a separate sheet member 70 (shown by diagonal lines in Fig. 9A ) in addition to the skin-side sheet 31 and the non-skin-side sheet 32. The left view of Fig. 9A shows the diaper 1 as viewed from the non-skin side, with the separate sheet member 70 shown in perspective. Specifically, as shown in the right view of Fig. 9A , the separate sheet member 70 is disposed on the skin side of the folded-back portion 32f. The separate sheet member 70 covers each opening 50 from the skin side. Here, the separate sheet member 70 is sized to extend between the pair of side joint portions 5, 5 in the left-right direction and to cover all of the openings 50 from the skin side in the up-down direction, but this is not limited thereto and the separate sheet member 70 may be sized to cover any number of openings 50. In this way, the separate sheet member 70 covers the openings 50 from the skin side, thereby reducing the risk of leakage through the openings 50. At the same time, as shown in Fig. 9B , when the diaper 1 is viewed from the non-skin side, the separate sheet member 70 can be seen from inside the openings 50, and it can be confirmed that the openings 50 are blocked by the separate sheet member 70, thereby alleviating the user's anxiety about leakage.

[0111] It should be noted that the above-described modified example is not limited to covering the openings 50 with a separate sheet member 70, and it is sufficient that the openings do not penetrate through the thickness direction of the back waistline portion 30. Although there are multiple openings 50, the openings 50 do not penetrate through the back waistline portion 30, which similarly reduces concerns about leakage.

[0112] Furthermore, the separate sheet member 70 may be, for example, a strip-shaped sweat-absorbent sheet that absorbs sweat from the wearer. In the case of a sweat-absorbent sheet, the sweat absorbed by the sweat-absorbent sheet evaporates through the openings 50, making it possible to prevent stuffiness.

[0113] When the separate sheet member 70 is a sweat-absorbent sheet, the sweat-absorbent sheet 70 may be, for example, a three-layer laminated nonwoven fabric (not shown). Such a laminated nonwoven fabric may include a first layer positioned on the skin-facing side of the laminated nonwoven fabric, a second layer positioned on the non-skin-facing side, and an intermediate layer positioned between the first and second layers, with the first and second layers containing hydrophilic fibers and the intermediate layer containing pulp fibers, and the first, second, and intermediate layers being integrated by a known hydroentangling method such as a water jet. Examples of the hydrophilic fibers include polyethylene terephthalate (PET) fibers whose fiber surfaces have been hydrophilically treated. While both the first and second layers may contain the hydrophilically treated polyethylene terephthalate (PET), it is preferable to use rayon fibers as the hydrophilic fibers of the second layer, as these fibers have excellent liquid diffusibility, post-entanglement strength, and versatility. It is preferable to use a pulp sheet containing at least pulp fibers as the intermediate layer. With such a sweat-absorbent sheet 70, sweat adhering to the skin is absorbed from the first layer, then passes through the middle layer and quickly transfers to the second layer, and if the second layer is made of rayon fiber, the excellent diffusion properties of the second layer allow sweat to diffuse within the sweat-absorbent sheet 70 and evaporate from the second layer. By providing the openings 50 on the non-skin side of the sweat-absorbent sheet 70, absorbed sweat can be more easily evaporated from the openings 50, making it less likely for the wearer to become stuffy.

[0114] The separate sheet member 70 may be a nonwoven fabric having openings smaller than the openings 50. When such a nonwoven fabric covers the openings 50 from the skin side, the openings 50 are not blocked, making the area around the openings less likely to become stuffy. Furthermore, as shown in Fig. 9B, when the diaper 1 is viewed from the non-skin side, the small openings in the nonwoven fabric are visible through the openings 50, confirming good breathability and providing a cool impression.

[0115] (Variation 1) Fig. 10 shows Variation 1 of another sheet member 70 arranged in the back-side waistband portion 30. The main difference between the diaper 1A shown in Fig. 10 and the above-described diaper 1 is that the back-side three-dimensional gathers 30RG are absent, and another sheet member 70 is arranged from the skin side so as to cover the area where the folded-back portion 32f of the non-skin-side sheet 32 ​​and the top sheet 12 overlap in the thickness direction. Fig. 10 also shows a core wrap sheet 11CV that covers the absorbent core 11. The another sheet member 70 of this variation is a sweat-absorbent sheet.

[0116] Specifically, as shown in FIG. 10 , the sweat-absorbent sheet 70 has an upper extension 70S in the back waistband 30 that extends upward in the vertical direction from the upper end 12a of the top sheet 12 in the vertical direction. In the diaper 1A, the region where the sweat-absorbent sheet 70 and the top sheet 12 overlap in the thickness direction is referred to as overlapping region A, and the region at the same vertical position as the upper extension 70S of the sweat-absorbent sheet 70 is referred to as region B. In addition, in the overlapping region A, a folded-back portion 32f is interposed between the sweat-absorbent sheet 70 and the top sheet 12. Note that the folded-back portion 32f (part of the non-skin-side sheet 32) is a hydrophobic sheet. The sweat-absorbent sheet 70 has a lower extension 70T (see FIG. 10 ) that extends downward in the vertical direction from the lower end 32fb of the hydrophobic sheet (folded-back portion 32f), and the lower extension 70T is arranged opposite the top sheet 12 so as to be in contact with the top sheet 12.

[0117] Here, the term "hydrophobic" means that liquid does not spread on the sheet surface and that the sheet surface has a contact angle greater than 90°. The contact angle is the angle between the horizontal plane and the tangent to the contour curve of the liquid at the intersection of the contour curve and the horizontal plane when the sheet has a horizontal surface and water (a droplet) on the horizontal surface. Therefore, the hydrophobic sheet has a contact angle greater than 90° and has a hydrophobic surface.

[0118] In this way, the hydrophobic sheet (folded portion 32f) is a sheet whose surface is hydrophobic and which does not have sweat-absorbent properties, and is typically made of a nonwoven fabric containing hydrophobic fibers. In this way, by interposing the folded portion 32f (hydrophobic sheet) which is impermeable to body fluids such as urine between the top sheet 12 arranged on the skin-facing side of the absorbent core 11 in the overlap region A and the sweat-absorbent sheet 70, liquid return from the absorbent core 11 to the sweat-absorbent sheet 70 side is effectively prevented.

[0119] In addition, in region B, a sweat-absorbing sheet 70 is arranged on the skin side so as to cover the opening 50, so that the sweat absorbed by the sweat-absorbing sheet 70 evaporates from the opening 50, making the back waist portion 30 less likely to become stuffy.

[0120] (Variation 2) Figure 11 shows Variation 2 of a different sheet member 70 disposed in the back waistband portion 30. The diaper 1B shown in Figure 11 does not have the back three-dimensional gathers 30RG, as in Variation 1, and differs from Variation 1 in that the fold-back portion 32f is not interposed between the sweat-absorbent sheet 70 and the top sheet 12 in the overlap region A where the sweat-absorbent sheet 70 and the top sheet 12 overlap in the thickness direction (hence, no hydrophobic sheet is interposed). Because the diaper 1B does not include a hydrophobic sheet (fold-back portion 32f), it is inferior to the diaper 1A, which does include a hydrophobic sheet, in terms of preventing liquid return from the absorbent core 11 to the sweat-absorbent sheet 70. However, the other configurations of the diaper 1B are substantially the same as those of Variation 1, and the diaper 1B achieves both smooth transfer of sweat from the sweat-absorbent sheet 70 to the top sheet 12 and prevention of liquid return. In addition, in region B, a sweat-absorbing sheet 70 is arranged on the skin side so as to cover the opening 50, so that the sweat absorbed by the sweat-absorbing sheet 70 evaporates from the opening 50, making the back waist portion 30 less likely to become stuffy.

[0121] (Variation 3) Fig. 12 shows Variation 3 of another sheet member 70 disposed in the back waistband portion 30. The diaper 1C shown in Fig. 12 does not have a back-side upright gather 30RG, as in Variations 1 and 2. The skin-side sheet 31 and the non-skin-side sheet 32 ​​are hydrophobic sheets made of hydrophobic fibers, allowing moisture (e.g., sweat from the wearer) to pass through. The skin-side sheet 31 and the non-skin-side sheet 32 ​​preferably contain at least one of polyethylene (PE) and polypropylene (PP). Polyethylene and polypropylene have extremely low water absorption rates, and the inclusion of either of these materials allows moisture (sweat) to pass through easily.

[0122] In addition, in Modification 3, another sheet member 70 (herein also referred to as hydrophilic sheet 70) that is a hydrophilic sheet is arranged on the non-skin side of the folded portion 32f (hydrophobic sheet). The hydrophilic sheet 70 is a hydrophilic sheet that can absorb moisture (such as sweat). The hydrophilic sheet 70 is preferably thin paper (e.g., tissue paper) containing liquid-absorbent pulp fibers. This improves the sweat absorbency of the hydrophilic sheet 70. Note that the definition of hydrophobic here is the same as above, and a "hydrophilic" sheet means that its surface has a contact angle of less than 90°.

[0123] By disposing the hydrophilic sheet 70 on the non-skin side of the folded portion 32f, the hydrophilic sheet 70 can absorb sweat through the folded portion 32f (hydrophobic sheet). Also, because the folded portion 32f is hydrophobic, sweat does not return and the skin does not get wet. In other words, the surface of the folded portion 32f is easily kept dry, and the wearer does not feel sticky and can enjoy a comfortable fit. This improves comfort and reduces the risk of heat rash and other irritations.

[0124] The hydrophilic sheet 70 is positioned closer to the skin than the skin-side sheet (hydrophobic sheet) 31. That is, two hydrophobic sheets (the skin-side sheet 31 and the unfolded portion of the non-skin-side sheet 32) overlap the hydrophilic sheet 70 on the non-skin-side side. This prevents sweat and other substances absorbed by the hydrophilic sheet 70 from leaking out of the back waistband 30 (the diaper 1). The folded-over portion 32f of the non-skin-side sheet 32 ​​and the hydrophilic sheet 70 are bonded with a hot-melt adhesive 35. While other bonding methods may be used, it is preferable to bond them in an intermittent pattern (multiple linear or dotted patterns) in the left-right or longitudinal direction. The intermittent application of the hot-melt adhesive 35 does not unnecessarily impede the passage of sweat from the folded-over portion 32f and does not impair the absorbency of the pulp fibers that make up the hydrophilic sheet 70. Furthermore, by providing the openings 50 on the non-skin side of the hydrophilic sheet 70, sweat absorbed by the hydrophilic sheet 70 can be more easily evaporated through the openings 50, making it possible to make the back waist portion 30 less prone to becoming stuffy.

[0125] ===Other=== The above embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

[0126] In the above-described embodiment, the opening 50 of the back waistline portion 30 is provided so as to be located above the absorbent main body 10 in the up-down direction, but this is not limited to this. For example, the opening 50 may be provided in a region that overlaps with the absorbent main body 10 in a plan view. The region that overlaps with the absorbent main body 10 is a region where moisture is more likely to accumulate, and providing the opening 50 makes it easier for such moisture to escape.

[0127] In the above-described embodiment, the distance between adjacent openings 50 in the left-right direction is short and they are closely spaced, but this is not limited to this, and the spacing between multiple openings 50 spaced apart in the left-right direction may be 10 mm or more. If the left-right spacing between openings 50 is less than 10 mm, the adjacent openings 50 may weaken the contraction force between the openings 50, which may reduce the fit and make the mask more susceptible to leakage. However, by setting the left-right spacing between openings 50 to 10 mm or more, such a decrease in contraction force can be prevented.

[0128] REFERENCE SIGNS LIST 1 Diaper (pants-type disposable diaper) 1A Diaper (pants-type disposable diaper) 1B Diaper (pants-type disposable diaper) 1C Diaper (pants-type disposable diaper) 5 Side joint portion 10 Absorbent body 11 Absorbent core 11CV Core wrap sheet 12 Top sheet 13 Back sheet 14 Outer sheet 15 Leg-surrounding elastic member 16 Leakage-preventing wall portion 16r Leakage-preventing wall elastic member 20 Abdominal waist portion 21 Skin-side sheet 22 Non-skin-side sheet 22f Folded-back portion 23 Waist elastic member 30 Dorsal waist portion 30RG Dorsal three-dimensional gather 30RGb Base end portion 30RGk Standing portion 30Rs Three-dimensional gather elastic member 31 Skin-side sheet 32 ​​Non-skin-side sheet 32f Folded-back portion 33 Waist elastic member 33ca Waist elastic member 33cb Waist elastic member 33t Waist elastic member 33t １ Overlapping waist elastic member (waist elastic member) 33t ２ , 33t ３ , 33t ４ Waist elastic member 35 Hot melt adhesive 38 Post-treatment tape 50 Opening 50a, 50a' First opening 50b, 50b' Second opening 50c Third opening 50G Opening group 50h, 50i, 50j, 50k, 50m, 50n Opening 70 Another sheet member (sweat absorbing sheet, hydrophilic sheet) 320 Strip-shaped non-skin side sheet 330 Continuous waist elastic member

Claims

1. A pants-type disposable diaper having an absorbent main body having an absorbent core with a vertical direction, a horizontal direction and a thickness direction perpendicular to each other, a ventral waist section, a rear waist section, and a plurality of waist elastic members stretchable in the horizontal direction, the waist elastic members being arranged at least on the rear waist section at intervals in the vertical direction, wherein the rear waist section has a skin side sheet and a non-skin side sheet provided on the non-skin side of the skin side sheet, the waist elastic members being provided between the skin side sheet and the non-skin side sheet, the rear waist section has an opening penetrating the skin side sheet and the non-skin side sheet in the thickness direction, the opening overlaps with the absorbent core in the horizontal direction and is located above the absorbent core in the vertical direction, the opening overlaps with at least one of the waist elastic members in the vertical direction, and the waist elastic members are discontinuous within the opening in the horizontal direction.

2. A pants-type disposable diaper comprising: an absorbent main body having an absorbent core, a ventral waist section, a rear waist section, and a plurality of waist elastic members arranged at intervals in the vertical direction at least on the rear waist section and stretchable in the horizontal direction, wherein the rear waist section has a skin-side sheet and a non-skin-side sheet provided on the non-skin-side side of the skin-side sheet, the waist elastic members being provided between the skin-side sheet and the non-skin-side sheet, the rear waist section has an opening penetrating the skin-side sheet and the non-skin-side sheet in the thickness direction, the opening overlaps with at least one of the waist elastic members in the vertical direction, the waist elastic members are discontinuous within the opening in the horizontal direction, the rear waist section has a rear three-dimensional gather at an upper end of the absorbent main body in the vertical direction, the rear side three-dimensional gathers have a base end that cannot stand up, and an upright portion that can stand up toward the skin in the thickness direction by a three-dimensional gather elastic member that contracts in the left-right direction, with the base end as a fulcrum, the upright portion being located lower in the vertical direction than the base end, and the base end being located lower in the vertical direction than the opening.

3. A pants-type disposable diaper according to claim 1 or 2, characterized in that the vertical length of the opening is less than 15 mm.

4. A pants-type disposable diaper as claimed in claim 3, characterized in that, in a stretched state, the opening is a slit extending in the up-down direction.

5. A pants-type disposable diaper as claimed in claim 3, characterized in that, in a stretched state, the opening is a cutout having a predetermined area cut out.

6. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that when one of the waist elastic members overlapping with the opening in the vertical direction is an overlapping waist elastic member, in a stretched state, the vertical length of the opening is longer than the vertical distance between the overlapping waist elastic member and another waist elastic member adjacent to it in the vertical direction.

7. A pants-type disposable diaper as claimed in claim 6, characterized in that when the upper waist elastic member adjacent to the overlapping waist elastic member in the vertical direction is an upper waist elastic member and the lower waist elastic member is a lower waist elastic member, in a stretched state, the vertical length of the opening is longer than the vertical length from the upper waist elastic member to the lower waist elastic member.

8. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that the magnitude of the force required to stretch the waist elastic member that overlaps with the opening in the vertical direction by a unit length in the left-right direction is greater than the magnitude of the force required to stretch the waist elastic member that does not overlap with the opening in the vertical direction by a unit length in the left-right direction.

9. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that, in the vertical direction, the opening overlaps with at least two of the waist elastic members adjacent in the vertical direction, and in a stretched state, the vertical distance between the two waist elastic members adjacent in the vertical direction is shorter than the vertical distance between two waist elastic members adjacent in the vertical direction and which do not overlap with the opening in the vertical direction.

10. A pants-type disposable diaper as claimed in claim 9, characterized in that the openings overlapping the two waist elastic members adjacent in the vertical direction are provided in a plurality at intervals in the left-right direction.

11. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that the opening is provided in the lower region when the area between the upper end of the absorbent body and the upper end of the rear waistband portion is divided into two in the vertical direction.

12. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that at least two of the openings are provided with a gap in the left-right direction, and when the opening on one side in the left-right direction is a first opening and the opening on the other side in the left-right direction is a second opening, in an extended state, the left-right distance from the upper end of the first opening to the upper end of the second opening is shorter than the vertical length of the openings, and the first opening and the second opening have an overlapping portion in the vertical direction, or the first opening and the second opening are provided with a gap in the vertical direction, and the distance from the lower end of the upper opening of the first opening and the second opening to the upper end of the lower opening is shorter than the vertical length of the openings.

13. A pants-type disposable diaper as described in claim 12, characterized in that the rear waist portion has an opening group including the first opening and the second opening, the opening groups are provided in plurality at intervals in the left-right direction, and in a stretched state, the left-right interval between two adjacent opening groups in the left-right direction is longer than the vertical length of the openings.

14. A pants-type disposable diaper as described in claim 12, characterized in that, in a stretched state, the first opening and the second opening are spaced apart in the vertical direction by at least 1 / 2 of the vertical length of the openings.

15. A pants-type disposable diaper according to claim 1 or 2, characterized in that a plurality of the openings are provided, and the plurality of openings do not overlap each other in the left-right direction.

16. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that a post-treatment tape is provided on the non-skin side of the rear waist portion, which is used when disposing of the pants-type disposable diaper after use, and the opening does not overlap with the post-treatment tape in the left-right direction.

17. A pants-type disposable diaper as claimed in claim 2, characterized in that the openings are provided on both outer sides of the absorbent core in the left-right direction.

18. A pants-type disposable diaper as described in claim 2, characterized in that the lower end in the vertical direction of the base end portion of the rear three-dimensional gather is located lower than the upper end in the vertical direction of the absorbent body.

19. A pants-type disposable diaper as described in claim 2, characterized in that the ventral waist portion and the rear waist portion are joined at both left-right sides by a pair of side joints, both left-right sides of the rear three-dimensional gathers are joined by the pair of side joints, and the rear three-dimensional gathers are not fixed between one end and the other end of the pair of side joints in the left-right direction.

20. A pants-type disposable diaper as described in claim 2, characterized in that the magnitude of the force required to stretch the three-dimensional gathered elastic member by a unit length in the left-right direction is smaller than the magnitude of the force required to stretch the waist elastic member that overlaps with the opening in the up-down direction by a unit length in the left-right direction.

21. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that the opening does not penetrate the rear waist portion in the thickness direction.

22. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that the skin side sheet and the non-skin side sheet have separate sheet members, and the separate sheet members cover the opening from the skin side.

23. A pants-type disposable diaper as claimed in claim 22, characterized in that the separate sheet member is a sweat-absorbing sheet.

24. A pants-type disposable diaper according to claim 22, characterized in that the separate sheet member is a nonwoven fabric having openings smaller than the openings.

25. A pants-type disposable diaper as claimed in claim 1 or 2, characterized in that the lower end of the opening in the vertical direction is located lower than the upper end of the absorbent body in the vertical direction in the ventral waist region.

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