Absorbent article

Abstract

An absorbent article (1) has a ventral waist panel (20) and a dorsal waist panel (30). At least one of the waist panels (20, 30) has a first region overlapping an absorbent core in the up-down direction and the left-right direction, and a second region overlapping an absorbent body (10) in the up-down direction and positioned in the range from the center position between an end of the absorbent body (10) and an end of the one of the waist panels (20, 30) to an end of the absorbent body (10) in the left-right direction. In the first region and the second region, a plurality of bonded sections (50) are arranged at intervals in the up-down direction, and the per-unit area of the bonded sections (50) in the first region is smaller than the per-unit area of the welded sections (50) in the second region.

Description

absorbent articles

[0001] The present invention relates to an absorbent article.

[0002] Patent Document 1 discloses a pants-type absorbent article including a front waistband, a rear waistband, and an absorbent main body, in each of the front and rear waistbands, a plurality of elastic members extending in the waist direction sandwiched between two sheet pieces. The two sheet pieces are joined together by welding, and a continuous stripe-shaped joint is provided in a direction (vertical direction) intersecting the stretch direction of the elastic members.

[0003] Republished WO2018 / 92559 Publication No. JP2023-15861A

[0004] As in Patent Document 1, the waistband portion has vertically continuous striped joints, which allow the two sheet pieces to form regular pleats upon contraction of the elastic member. However, the vertically continuous joints (welded joints) and pleats increase the vertical rigidity of the waistband portion, potentially hindering vertical deformation of the waistband portion. This makes it difficult for the waistband portion and the absorbent core that overlaps it to conform to the curves of the wearer's lower abdomen and buttocks. This can result in reduced comfort or the risk of a gap between the absorbent core and the wearer, resulting in bodily waste leakage. Furthermore, because the wearer's legs abut the waistband portions laterally outboard of the absorbent main body, the vertical rigidity of the waistband portion restricts leg movement, potentially reducing comfort.

[0005] Patent Document 2 discloses a pants-type absorbent article in which a ventral waistband and a dorsal waistband are joined at both lateral ends by a pair of side welds. In Patent Document 2, a wide weld is provided in the inner edge region (a range of 20 mm inward from the inner edge of the side weld). This makes the inner edge region less stretchable, making the side weld more likely to tear during donning and doffing. However, in other regions of the waistband, such as the region overlapping the absorbent core or the region close to the absorbent main body (specifically, the region located from the center between the end of the absorbent main body and the end of the ventral or dorsal waistband to the end of the absorbent main body), the lateral lengths of the welds and the spacing between adjacent welds are constant. In this case, if the area ratio of the welds is large and the rigidity is high in the region of the waistband overlapping the absorbent core, the absorbent core may not be able to conform to the wearer's body. Conversely, even though the area of ​​the waistband close to the absorbent body is an area that is likely to be subjected to force from the wearer's legs, if the area ratio of the welded area is small, the force with which the welded area joins the two sheets is weak, and there is a risk that the two sheets will peel off due to leg movements such as walking or sitting.

[0006] The present invention was made in consideration of the above-mentioned problems, and its purpose is to prevent peeling between the skin-side sheet and the non-skin-side sheet in an absorbent article in which the skin-side sheet and the non-skin-side sheet of the waist panel are joined by multiple welding joints, while suppressing a decrease in comfort and leakage of excrement.

[0007] The main invention for achieving the above object is an absorbent article having an absorbent main body having a vertical direction and a horizontal direction perpendicular to each other and equipped with an absorbent core, a ventral waist panel on the ventral side, and a vertical waist panel on the vertical side, and a vertical waist panel on the vertical side, wherein at least one of the ventral waist panel and the vertical waist panel has an elastic member, a skin-side sheet arranged closer to the skin than the elastic member, and a non-skin-side sheet arranged closer to the skin than the elastic member, and the skin-side sheet and the non-skin-side sheet are joined by a plurality of welded portions, and when the absorbent article is in a stretched state, the one waist panel has: a first region overlapping with the absorbent core in the vertical direction and the horizontal direction; and a second region overlapping with the absorbent main body in the vertical direction and located in the horizontal direction from a center position between an end of the absorbent main body and an end of the one waist panel to the end of the absorbent main body, The absorbent article is characterized in that a plurality of the welded portions are arranged at intervals in the up-down direction in the first region and the second region, and the area of ​​the welded portions per unit area in the first region is smaller than the area of ​​the welded portions per unit area in the second region. Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to prevent peeling of the skin-side sheet and the non-skin-side sheet in an absorbent article in which the skin-side sheet and the non-skin-side sheet of the waist panel are joined by multiple welding joints, while suppressing a decrease in comfort and leakage of excrement.

[0009] 1 is a schematic perspective view of the diaper 1; 2 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as viewed from the skin side; 3 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as viewed from the non-skin side; 4 is a cross-sectional view taken along the line A-A in FIG. 2; 5A and 5B are explanatory diagrams of a method for fastening the waist elastic members 23, 33; 6 is a plan view of the ventral waist panel 20P in an extended state; 7 is a plan view of the back waist panel 30P in an extended state; 8 is an explanatory diagram of the patterns of the welded portions 50 in the narrow spacing region Rn and the wide spacing region Rw; 9A and 9B are explanatory diagrams of the third region R3 and the fourth region R4; 10A and 10B are explanatory diagrams of the first region R1 and the fifth region R5; 11A and 11B are explanatory diagrams of the first region R1 and the sixth to eighth regions R6 to R8; 11B are partially enlarged views of the first region R1 and the second region R2; and 11C are diagrams showing modified patterns of the welded portions 50.

[0010] The present specification and the accompanying drawings make at least the following clear: Aspect 1 is an absorbent article having an absorbent main body having a vertical direction and a horizontal direction perpendicular to each other and including an absorbent core, a ventral waist panel on the ventral side, and a dorsal waist panel on the dorsal side, wherein at least one of the ventral waist panel and the dorsal waist panel has an elastic member, a skin-side sheet arranged closer to the skin than the elastic member, and a non-skin-side sheet arranged closer to the skin than the elastic member, and the skin-side sheet and the non-skin-side sheet are joined by a plurality of welded parts, and when the absorbent article is in a stretched state, the one of the waist panels has an elastic member, a skin-side sheet arranged closer to the skin than the elastic member, and a non-skin-side sheet arranged closer to the skin than the elastic member, and the skin-side sheet and the non-skin-side sheet are joined by a plurality of welded parts, and when the absorbent article is stretched, The waist panel has a first region that overlaps with the absorbent core in the vertical and horizontal directions, and a second region that overlaps with the absorbent main body in the vertical direction and is located in the range from the center position between the end of the absorbent main body and the end of one of the waist panels to the end of the absorbent main body in the horizontal direction, and in the first and second regions, multiple welded portions are arranged at intervals in the vertical direction, and the area of ​​the welded portions per unit area in the first region is smaller than the area of ​​the welded portions per unit area in the second region.

[0011] According to Aspect 1, the welded portions are distributed vertically in the first and second regions, allowing the first and second regions to more easily deform vertically along the wearer's body. Because the area ratio of the welded portions in the first region is small, the rigidity of the first region is reduced, allowing the absorbent core overlapping the first region to more easily deform along the wearer's body. This reduces discomfort. Furthermore, gaps are less likely to form between the absorbent core and the wearer, reducing the risk of bodily waste leakage. Meanwhile, the second region is located at the boundary with the region joined to the absorbent main body, and is more susceptible to the forces of leg movements such as walking and sitting. Therefore, the large area ratio of the welded portions in the second region strengthens the bonding strength between the skin-side sheet and the non-skin-side sheet, preventing separation of the skin-side sheet and the non-skin-side sheet in the second region.

[0012] (Aspect 2) An absorbent article as described in Aspect 1, wherein, when the absorbent article is in a stretched state, one of the waist panels has a third region that overlaps with the absorbent main body in the thickness direction, and the area of ​​the welded portion per unit area in the third region is smaller than the area of ​​the welded portion per unit area in the second region.

[0013] According to Aspect 2, the rigidity of the third region is reduced, allowing the absorbent body overlapping the third region to easily deform along the wearer's body. This prevents a decrease in comfort and reduces leakage of excrement. Meanwhile, the large area ratio of the welded portion in the second region strengthens the bonding strength between the skin-side sheet and the non-skin-side sheet, preventing separation between the skin-side sheet and the non-skin-side sheet in the second region.

[0014] (Aspect 3) An absorbent article according to Aspect 1 or Aspect 2, wherein the ventral waist panel and the dorsal waist panel are joined to each other by a pair of side joints at both ends in the left-right direction, and when the absorbent article is stretched, one of the waist panels has a third region that overlaps with the absorbent main body when viewed in the thickness direction, and a fourth region that overlaps with the absorbent main body in the up-down direction and is located in the left-right direction in a range from a position 20 mm inward from the inner end of the side joint to the end of the absorbent main body, and the area of ​​the welded portion per unit area in the third region is smaller than the area of ​​the welded portion per unit area in the fourth region.

[0015] According to Aspect 3, the rigidity of the third region is reduced, allowing the absorbent main body overlapping the third region to more easily deform along the wearer's body. This prevents a decrease in comfort and reduces leakage of body waste. Meanwhile, in the fourth region, which is located inside the sides of the wearer's waist and is more likely to deform due to the wearer's leg movements, the large area ratio of the welded portions strengthens the bonding strength between the skin-side sheet and the non-skin-side sheet, preventing separation between the skin-side sheet and the non-skin-side sheet in the fourth region.

[0016] (Aspect 4) An absorbent article according to any one of aspects 1 to 3, having a display portion visible from the non-skin side, wherein when the absorbent article is stretched and the one waist panel is viewed in the thickness direction, the display portion has a portion that overlaps with the first region.

[0017] According to Aspect 4, in the first region, the welded portion can suppress lifting of the non-skin-side sheet relative to the skin-side sheet, while reducing the area ratio of the welded portion that is welded to form a film, thereby suppressing a decrease in visibility of the display portion that overlaps the first region.

[0018] (Aspect 5) An absorbent article described in any of Aspects 1 to 4, wherein, in a stretched state of the absorbent article, one of the waist panels overlaps with the absorbent core in the vertical direction and has a fifth region located in the range from the end of the absorbent core to the end of one of the waist panels in the horizontal direction, and the area of ​​the welded portion per unit area in the first region is smaller than the area of ​​the welded portion per unit area in the fifth region.

[0019] According to Aspect 5, the rigidity of the first region is reduced, allowing the absorbent core overlapping the first region to more easily deform along the wearer's body. This prevents a decrease in comfort and reduces leakage of body waste. Meanwhile, in the fifth region, which is affected by the wearer's leg movement, the large area ratio of the welded portion strengthens the bonding strength between the skin-side sheet and the non-skin-side sheet. This prevents peeling between the skin-side sheet and the non-skin-side sheet in the fifth region.

[0020] (Aspect 6) An absorbent article described in any of Aspects 1 to 5, wherein, in a stretched state of the absorbent article, one of the waist panels has a sixth region that overlaps with the absorbent main body in the left-right direction and is located in a range from the upper end of the absorbent main body to the upper end of one of the waist panels, and the area of ​​the welded portion per unit area in the sixth region is larger than the area of ​​the welded portion per unit area in the first region.

[0021] According to Aspect 6, the rigidity of the first region is reduced, allowing the absorbent core overlapping the first region to easily deform along the wearer's body. This prevents a decrease in comfort and reduces leakage of body waste. Meanwhile, the rigidity of the upper end of the waist panel is increased, making it easier to maintain the shape of the upper end of the waist panel while wearing the garment. Furthermore, the increased rigidity of the upper end of the waist panel prevents the upper end from curling when worn.

[0022] (Aspect 7) An absorbent article described in any of Aspects 1 to 6, wherein, in a stretched state of the absorbent article, one of the waist panels has a seventh region that overlaps with the absorbent main body in the left-right direction and is located in a range from the upper end of the absorbent core to the upper end of the absorbent main body, and the area of ​​the welded portion per unit area in the seventh region is larger than the area of ​​the welded portion per unit area in the first region.

[0023] According to Aspect 7, the rigidity of the first region is reduced, allowing the absorbent core overlapping the first region to more easily deform along the wearer's body. This prevents a decrease in comfort and reduces leakage of body waste. Meanwhile, the rigidity of the upper end of the absorbent main body is increased, making it easier for the lifting force of the upper end of the waist panel to be transmitted to the upper end of the absorbent main body. This allows the lifting force to be efficiently transferred to the upper end of the absorbent main body, making it easier to lift the absorbent article when worn and preventing it from slipping down during wear.

[0024] (Aspect 8) An absorbent article described in any of aspects 1 to 7, wherein, in a stretched state of the absorbent article, one of the waist panels has an eighth region that overlaps with the absorbent main body in the vertical direction and is located in the range from the end of the absorbent core to the end of the absorbent main body in the horizontal direction, and the area of ​​the welded portion per unit area in the first region is smaller than the area of ​​the welded portion per unit area in the eighth region.

[0025] According to Aspect 8, it is possible to reduce the rigidity of the first region of the absorbent main body that overlaps the absorbent core, which is more likely to cause leakage, thereby making it easier for the absorbent core to deform along the wearer's body and more reliably preventing leakage of body exudates.

[0026] (Aspect 9) The absorbent article according to any one of Aspects 1 to 8, wherein the average strength of the welded portions in the first region is greater than the average strength of the welded portions in the second region.

[0027] According to Aspect 9, in the first region, the area ratio of the welded portions is small, but the strength of each welded portion tends to be strong, thereby preventing peeling between the skin side sheet and the non-skin side sheet in the first region.

[0028] (Aspect 10) The absorbent article according to aspect 5, wherein the contractile force in the left-right direction of the first region is weaker than the contractile force in the left-right direction of the fifth region.

[0029] According to Aspect 10, the contraction of the absorbent core overlapping the first region can be suppressed. Therefore, deterioration in comfort can be suppressed and leakage of excrement can be suppressed. Meanwhile, the fifth region can more easily follow the movement of the wearer's legs, maintaining a good fit and suppressing deterioration in comfort.

[0030] (Aspect 11) An absorbent article described in any of Aspects 1 to 10, wherein the elastic member is a thread-like elastic member, the second region has a welded portion that fixes the position of the elastic member, and the first region has no welded portion that fixes the position of the elastic member in the left-right center.

[0031] According to Aspect 11, the stretchable portions of the elastic members are not fixed in the left-right center of the first region, thereby reducing the stretchability (contractile force). This suppresses the contraction of the absorbent core, thereby preventing a decrease in comfort and reducing the risk of body waste leakage. In the second region, the stretchable portions of the elastic members are fixed, providing stretchability. Fixing the elastic members with welded portions eliminates the need to fix the elastic members to the sheet with, for example, adhesive, making the contraction of the elastic members flexible due to leg movement and reducing the risk of sheet breakage.

[0032] (Aspect 12) An absorbent article described in any of Aspects 1 to 11, wherein the elastic member is a thread-like elastic member, and when the absorbent article is in a stretched state, the second region has a group of welds in which a plurality of the welds are arranged in the vertical direction, and in the second region, the position of the elastic member is fixed by being sandwiched between two of the welds that are adjacent to each other in the vertical direction, and the first region has a plurality of overlapping welds that are welds that overlap with the group of welds in the vertical direction, and the minimum vertical distance between two overlapping welds that are adjacent to each other in the vertical direction is wider than the minimum vertical distance between two of the welds that are adjacent to each other in the vertical direction.

[0033] According to Aspect 12, in the first region, the elastic member passes between the overlapping welds, reducing stretchability (contractile force). This reduces contraction of the absorbent core, thereby preventing a decrease in comfort and reducing leakage of body waste. In the second region, the elastic member is sandwiched between the welds, providing stretchability. Because the two upper and lower welds sandwiching the elastic member are located within the group of welds, the bond strength between the skin-side sheet and the non-skin-side sheet is increased around the two welds sandwiching the elastic member, preventing peeling of the welds sandwiching the elastic member even when excessive tensile force is applied to the elastic member.

[0034] (Aspect 13) An absorbent article as described in Aspect 12, wherein at both left-right end portions of the first region, the position of the elastic member is fixed by being sandwiched between two adjacent welded portions in the vertical direction.

[0035] According to Aspect 13, stretchability is exhibited at both left-right ends of the first region, allowing both left-right ends of the absorbent core to fit closely to the wearer's body, thereby reducing the risk of bodily waste leakage. Furthermore, if the elastic member in the first region is cut to further reduce the stress on the absorbent core, the cut ends of the elastic member will shrink in the left-right direction due to the recoil stress. Even in this case, by restricting the position of the elastic member at both ends of the first region, it is possible to prevent a reduction in the stress of the elastic member in areas outside the left-right direction of the first region that are affected by the wearer's leg movement.

[0036] (Aspect 14) An absorbent article according to any one of aspects 1 to 13, wherein the rear waist panel has the first region and the second region, the non-skin side sheet of the rear waist panel is a nonwoven fabric, and a post-treatment tape is bonded to the non-skin side sheet with an adhesive, and when the absorbent article is in a stretched state, the first region on the rear side has a portion that overlaps with the post-treatment tape when viewed in the thickness direction.

[0037] According to aspect 14, in the first region, the area of ​​the film-formed welded portion is smaller, so that the adhesive for bonding the post-treatment tape to the waist panel penetrates into the nonwoven fabric, increasing the bonding strength of the post-treatment tape.

[0038] (Aspect 15) An absorbent article as described in Aspect 14, wherein the ventral waist panel and the dorsal waist panel each have the first region and the second region, and the area of ​​the welded portion per unit area is different between the dorsal first region and the ventral first region.

[0039] According to Aspect 15, the area ratio of the welded portion in the first region on the back side is small, which reduces the area of ​​the welded portion formed into a film, thereby increasing the bonding strength of the post-treatment tape. Conversely, the area ratio of the welded portion in the first region on the back side is large, which increases the bonding strength between the skin-side sheet and the non-skin-side sheet on the back side. This prevents the skin-side sheet and the non-skin-side sheet from peeling off when the user is in a lying position.

[0040] (Aspect 16) An absorbent article according to any one of Aspects 1 to 15, wherein, in a stretched state of the absorbent article, the distance between adjacent welded portions in the left-right direction in the first region is greater than the length of each of the adjacent welded portions in the left-right direction.

[0041] According to Aspect 16, the welded portions are dispersed in the left-right direction in the first region, which makes it easier for the first region to deform in the left-right direction along the wearer's body. Also, the area ratio of the welded portions in the first region can be reduced.

[0042] ================ <<Basic Configuration of Pants-Type Disposable Diaper>> As an example of an absorbent article according to this embodiment, a pants-type disposable diaper 1 for infants (hereinafter also referred to as "diaper 1") will be described. However, the absorbent article according to the present invention is not limited to pants-type disposable diapers, and can also be applied to shorts-type napkins and absorbent articles in which one or more locations around the waist are separable and rejoinable, that is, absorbent articles that combine pants and tape types. Furthermore, the intended wearer of the absorbent article is not limited to infants, but may also be an adult or a living organism such as an animal.

[0043] FIG. 1 is a schematic perspective view of a diaper 1. FIG. 2 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as viewed from the skin side. FIG. 3 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as viewed from the non-skin side. FIG. 4 is a cross-sectional view taken along the line A-A in FIG. 2. The "unfolded state" of the diaper 1 refers to a state in which the diaper 1 in the pants-type state shown in FIG. 1 is unfolded at the side seams SS (described below) on both sides in the lateral direction, and the diaper 1 is unfolded on a flat surface. The "stretched state" of the diaper 1 refers to a state in which the product (diaper 1) is stretched without wrinkles, specifically, a state in which the dimensions of each component constituting the diaper 1 (e.g., the absorbent main body 10, the ventral outer member 20, etc.) are stretched to lengths that are equal to or close to the dimensions of the individual components.

[0044] The diaper 1 (FIG. 1) in this pants-type state has three mutually perpendicular directions: vertical, horizontal, and front-to-rear, 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 also referred to as the upper side, and the side facing the wearer's crotch is also referred to as the lower side. In the front-to-rear direction, the front side corresponding to the wearer's abdominal side is also referred to as the abdominal side, and the rear side is also referred to as the dorsal side. Furthermore, the diaper 1 has a thickness direction in which materials are layered, as shown in FIG. 4, and the side in contact with the wearer in the thickness direction is referred to as the skin side, and the opposite side is referred to as the non-skin side.

[0045] The diaper 1 includes an absorbent main body 10 having an absorbent core 11, a ventral outer member 20 (ventral waist panel 20P) on the ventral side, and a rear outer member 30 (rear waist panel 30P) on the rear side. In the following description, the ventral outer member 20 and the rear outer member 30 are collectively referred to as the "outer members 20, 30," and the ventral waist panel 20P and the rear waist panel 30P are collectively referred to as the "waist panels 20P, 30P." The outer members 20, 30 are joined to the non-skin-facing side of the absorbent main body 10 with an adhesive or the like. The diaper 1 in an unfolded state is folded in half at a longitudinal center position CL of the absorbent main body 10, and the ventral outer member 20 (ventral waist panel 20P) and the rear outer member 30 (rear waist panel 30P) are joined to each other at a pair of side joining portions SS at both lateral ends, thereby forming a pants-type diaper. Examples of joining methods for the side joining portions SS include welding, joining with an adhesive, etc. The longitudinal direction of the absorbent main body 10 corresponds to the up-down direction of the pants-type diaper 1.

[0046] As shown in Figure 4, the absorbent body 10 has an absorbent core 11, 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 exterior sheet 14. The absorbent core 11 may be any material that absorbs and retains excreted liquid, and examples thereof include a liquid-absorbent material such as pulp fiber or a superabsorbent polymer molded into a predetermined shape. The absorbent core 11 may also be covered with a liquid-permeable sheet such as tissue paper or a nonwoven fabric.

[0047] A pair of longitudinally extending leakage barrier walls 2 are provided on both lateral sides of the absorbent body 10. Although not shown, for example, portions of the outer sheet 14 extending from both lateral sides of the non-skin side of the back sheet 13 are folded at multiple locations and provided on both lateral sides of the skin side of the top sheet 12 to form the leakage barrier walls 2. The stretchability of the leakage barrier elastic members 15 allows the leakage barrier walls 2 to stand up toward the wearer's skin. Leg-hole elastic members 16 are provided laterally outboard of the leakage barrier walls 2. The stretchability of the leg-hole elastic members 16 allows the diaper 1 to fit around the wearer's legs.

[0048] The ventral outer member 20 (ventral waist panel 20P) and the rear outer member 30 (rear waist panel 30P) each include waist elastic members 23, 33 (elastic members), skin-side sheets 21, 31 disposed closer to the skin than the waist elastic members 23, 33, and non-skin-side sheets 22, 32 disposed closer to the skin than the waist elastic members 23, 33. Examples of the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 include nonwoven fabrics such as spunbond nonwoven fabrics and SMS (spunbond / meltblown / spunbond) nonwoven fabrics, as well as other flexible sheet materials. Examples of constituent fibers of the nonwoven fabric include single fibers of thermoplastic resins such as polypropylene (PP) or polyethylene (PE), and composite fibers having a sheath-core structure such as PE and PP. While the basic configuration of the diaper 1 has been described above, the above configuration of the diaper 1 is merely an example and is not intended to be limiting.

[0049] <<Regarding Positioning of Waist Elastic Members>> Figures 5A and 5B are explanatory diagrams of a method for fastening the waist elastic members 23, 33. The skin-side sheets 21, 31 and non-skin-side sheets 22, 32 of the exterior members 20, 30 (waist panels 20P, 30P) are joined by multiple welds 50. Examples of methods for forming the welds 50 include well-known welding methods such as ultrasonic welding and thermal welding. The multiple welds 50 are arranged vertically and spaced apart, as shown in Figures 6 to 8 (described later). In this embodiment, the welds 50 are parallelogram-shaped, and the vertically aligned rows of multiple welds 50 meander slightly horizontally. However, the shape and arrangement of the welds 50 are not particularly limited. For simplicity's sake, in Figures 5A and 5B, the welds 50 are rectangular, and two vertically adjacent welds 50 are positioned at the same horizontal position.

[0050] The multiple welded portions 50 in this embodiment not only have the function of joining the skin side sheets 21, 31 and the non-skin side sheets 22, 32, but also have the function of attaching (fixing) the waist elastic members 23, 33 to the skin side sheets 21, 31 and the non-skin side sheets 22, 32.

[0051] The skin side sheets 21, 31 and non-skin side sheets 22, 32 joined by the welded portion 50 may be two separate sheets as shown in Fig. 4, or may be a two-layer sheet formed by folding back a single sheet. The welded portion 50 may also join three or more layers of sheets, including other sheets laminated on the skin side sheets 21, 31 and non-skin side sheets 22, 32.

[0052] In the exterior members 20, 30, the positions of the waist elastic members 23, 33 are fixed by sandwiching thread-like waist elastic members 23, 33 between two vertically adjacent welded portions 50 among the multiple welded portions 50 lined up in the vertical direction. In the following description, the pair of welded portions 50 sandwiching the waist elastic members 23, 33 therebetween is also referred to as a pair of welded portions 51.

[0053] 5A, a pair of welded portions 50, 50 constituting a welded portion pair 51 are arranged vertically with a gap GH50 therebetween. The size of the gap GH50 is set to be equal to or slightly larger than the outer diameter d1 of the waistline elastic members 23, 33 when the waistline panels 20P, 30P are fully stretched in the left-right direction (GH50≧d1).

[0054] The waist elastic members 23, 33 become thicker as they contract in the left-right direction. Therefore, as shown in FIG. 5B , the distance GH50 between the pairs of welded portions 51 is set smaller than the maximum outer diameter d2 of the waist elastic members 23, 33 when they are contracted in the left-right direction (i.e., when the waist panels 20P, 30P are in their natural state) (GH50<d2). This allows the waist elastic members 23, 33, when contracted in the left-right direction, to be sandwiched between the pairs of welded portions 51 (restricting expansion in the up-down direction). Therefore, the position (movement) of the waist elastic members 23, 33 in the left-right and up-down directions relative to the skin side sheets 21, 31 and the non-skin side sheets 22, 32 is restricted.

[0055] Therefore, the waist elastic members 23, 33 can be attached to the skin side sheets 21, 31 and the non-skin side sheets 22, 32 without using adhesive or by using a reduced amount of adhesive, thereby imparting stretchability to the outer covering members 20, 30. This makes it possible to prevent a decrease in the flexibility of the outer covering members 20, 30 due to hardening of the adhesive. In addition, it is possible to prevent a decrease in the elastic properties of the waist elastic members 23, 33 due to hardening of the adhesive.

[0056] In this embodiment, the waist elastic member (elastic member) is exemplified as a thread-like elastic member, but is not limited thereto. The waist elastic member may also be a sheet-like elastic member (e.g., a stretchable film or a stretchable nonwoven fabric). The sheet-like elastic member is disposed between the skin-side sheet and the non-skin-side sheet, and these sheet members are joined together by a welding portion, thereby imparting stretchability to the waist panel.

[0057] <<Regarding the Area Ratio of the Welded Portions 50>> Fig. 6 is a plan view of the ventral waist panel 20P in a stretched state. Fig. 7 is a plan view of the back waist panel 30P in a stretched state. Fig. 8 is an explanatory diagram of the patterns of the welded portions 50 in each of the narrow-spacing region Rn and the wide-spacing region Rw. In the following description, the portions of the absorbent main body 10 or the absorbent core 11 forward of the folded position of the pants-type diaper 1, i.e., the longitudinal center position CL of the diaper 1 in the unfolded state, will also be referred to as front portions 10F and 11F, respectively, and the portions of the absorbent main body 10 or the absorbent core 11 rearward will also be referred to as rear portions 10B and 11B, respectively (see Fig. 2 ).

[0058] In addition, when the diaper 1 is in an unfolded state (see FIG. 3 ), the portion of the ventral outer member 20 located above (toward the waist) an imaginary line Lv1 connecting the lower ends 20Ed of the lateral side edges 20E of the ventral outer member 20 is referred to as the "ventral waist panel 20P." Similarly, when the diaper 1 is in an unfolded state, the portion of the back outer member 30 located above an imaginary line Lv2 connecting the lower ends 30Ed of the lateral side edges 30E of the back outer member 30 is referred to as the "back waist panel 30P." When the diaper 1 (absorbent article) has side seams SS on both lateral sides, as in this embodiment, the unfolded state ( FIGS. 2 and 3 ) refers to the state in which the side seams SS are unsewn and the diaper 1 is opened flat. Some absorbent articles do not have side seams SS, but have two waist-sizing sections that can be separated and rejoined using hook-and-loop fasteners or the like, combining pants-type and tape-type structures. In this case, the state in which the absorbent article is opened flat by separating the two separable portions is referred to as the unfolded state. In addition, if the absorbent article has a side joint portion SS on only one side in the left-right direction and one portion around the waist on the other side is separable and rejoinable, the state in which the one separable portion is unjoined from the side joint portion SS and the absorbent article is opened flat is referred to as the unfolded state.

[0059] As shown in FIG. 2 , the back-side outer member 30 of this embodiment has an extension 30D extending downward from the back-side waist panel 30P. The extension 30D can cover the wearer's buttocks. However, the above is not limiting, and the back-side outer member 30 may not have the extension 30D, or the ventral-side outer member 20 may have a portion extending downward from the ventral-side waist panel 20P. Furthermore, in the diaper 1 of this embodiment, the ventral-side outer member 20 and the back-side outer member 30 are formed as separate members, and the non-skin-side side of the absorbent main body 10 is exposed in the crotch region. For example, the diaper 1 may be formed as a three-member outer member: the ventral-side outer member 20, the back-side outer member 30, and a crotch region panel connecting them. Alternatively, the outer member may be formed as a single member that is continuous from the ventral-side waist panel 20P to the back-side waist panel 30P.

[0060] As shown in Fig. 6, when the diaper 1 is stretched, the ventral waist panel 20P has a first region R1 and a second region R2. The first region R1 is a region that overlaps with the absorbent core 11 (specifically, the front portion 11F of the absorbent core 11) in the up-down and left-right directions. The second region R2 is a region that overlaps with the absorbent main body 10 (specifically, the front portion 10F of the absorbent main body 10) in the up-down direction and is located in a range from a central position 20c1 between the end 10e of the absorbent main body 10 and the end 20e of the ventral waist panel 20P to the end 10e of the absorbent main body 10 in the left-right direction.

[0061] 7, when the diaper 1 is stretched, the back waist panel 30P also has a first region R1 and a second region R2. The first region R1 is a region that overlaps with the absorbent core 11 (specifically, the rear portion 11B of the absorbent core 11) in the up-down and left-right directions. The second region R2 is a region that overlaps with the absorbent main body 10 (specifically, the rear portion 10B of the absorbent main body 10) in the up-down direction and is located in the left-right direction from a central position 30c1 between the end 10e of the absorbent main body 10 and the end 30e of the back waist panel 30P to the end 10e of the absorbent main body 10.

[0062] The absorbent core 11 of this embodiment has a narrowed portion on the inside in the width direction, and the width of the absorbent core 11 varies depending on the vertical position. In this case, the maximum width in the left-right direction of the part of the absorbent core 11 that overlaps with the ventral or dorsal waist panel 20P, 30P corresponds to the width of the first region R1. In other words, the first region R1 is a rectangular region.

[0063] The second regions R2 are located on the left and right sides of the first region R1. Specifically, the left-side second region R2 is located from a central position 20c1, 30c1 between the left end 10e of the absorbent main body 10 and the left end 20e, 30e of the ventral or dorsal waist panel 20P, 30P to the left end 10e of the absorbent main body 10. The right-side second region R2 is located from a central position 20c1, 30c1 between the right end 10e of the absorbent main body 10 and the right end 20e, 30e of the ventral or dorsal waist panel 20P, 30P to the right end 10e of the absorbent main body 10. Therefore, in the left-right direction, the length W1 of the second region R2 is equal to the length W1 from the central position 20c1, 30c1 to the end 20e, 30e of the waist panel 20P, 30P.

[0064] In the following description, the first region R1 and the second region R2 of the ventral waist panel 20P are also referred to as the ventral first region R1 and the ventral second region R2. The first region R1 and the second region R2 of the dorsal waist panel 30P are also referred to as the dorsal first region R1 and the dorsal second region R2.

[0065] In the first region R1 and the second region R2, the plurality of welded portions 50 are arranged at intervals in the vertical direction. That is, in the first region R1 and the second region R2, the plurality of welded portions 50 are arranged dispersedly in the vertical direction. Therefore, compared to a case where, for example, striped welded portions are provided that are continuous in the vertical direction, the waist panels 20P, 30P of this embodiment are more easily deformed in the vertical direction. Therefore, the waist panels 20P, 30P and the portions of the absorbent core 11 that overlap them are more likely to conform to the wearer's body (the vertical curvature of the lower abdomen and buttocks).

[0066] Furthermore, the area of ​​the welded portions 50 per unit area in the first region R1 on the ventral side is smaller than the area of ​​the welded portions 50 per unit area in the second region R2 on the ventral side. Similarly, the area of ​​the welded portions 50 per unit area in the first region R1 on the dorsal side is smaller than the area of ​​the welded portions 50 per unit area in the second region R2 on the dorsal side.

[0067] The area of ​​the welded portions 50 per unit area (hereinafter also referred to as the area ratio of the welded portions 50) can be calculated as follows: When the diaper 1 is stretched, the total area A1 of the multiple welded portions 50 included in the corresponding region (first region R1 or second region R2) is divided by the total area A2 of the corresponding region (first region R1 or second region R2) (A1 / A2).

[0068] The first region R1 overlaps with the absorbent core 11. Therefore, in the first region R1, the multiple welded portions 50 are vertically dispersed, and the area ratio of the welded portions 50 is small, which further reduces the rigidity of the first region R1. Therefore, the portion of the absorbent core 11 that overlaps with the first region R1 is more likely to deform in line with the wearer's body. As a result, discomfort to the wearer can be reduced, and a decrease in comfort can be suppressed. Furthermore, gaps are less likely to form between the absorbent core 11 and the wearer, which can suppress leakage of body waste.

[0069] On the other hand, the portions of the waist panels 20P, 30P laterally outboard of the absorbent main body 10 deform due to the wearer's leg movements. Therefore, the second region R2, which is closer to the absorbent main body 10, is located at the boundary between the portions of the waist panels 20P, 30P fixed to the absorbent main body 10 and the portions of the waist panels 20P, 30P that deform due to the wearer's leg movements. Therefore, the second region R2 is more susceptible to the force of the wearer's leg movements, such as walking or sitting. Therefore, in the second region R2, the multiple welded portions 50 are vertically dispersed, facilitating vertical deformation, which reduces the restriction of the wearer's leg movements. As a result, a decrease in comfort can be suppressed. Furthermore, by increasing the area ratio of the welded portions 50 in the second region R2, the rigidity of the second region R2 is increased, and the bonding area between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 is increased, strengthening the bonding strength between the two sheets. Therefore, peeling between the skin side sheets 21, 31 and the non-skin side sheets 22, 32 in the second region R2 due to leg movements of the wearer can be suppressed.

[0070] In the diaper 1 of this embodiment, the regions in which the waist elastic members 23, 33 are arranged are divided into a narrow spacing region Rn and a wide spacing region Rw. As shown in Fig. 8 , the narrow spacing region Rn has a plurality of welded portion groups 52, each of which includes a plurality of (six in this example) welded portions 50a arranged at narrow spacings GH1 in the vertical direction. The welded portion groups 52 are arranged in accordance with the vertical arrangement of the waist elastic members 23, 33. The waist elastic members 23, 33 are sandwiched between any two welded portions 50a in each welded portion group 52, i.e., between two welded portions 50a adjacent to each other in the vertical direction. This fixes the positions of the waist elastic members 23, 33.

[0071] On the other hand, the wide spacing region Rw has multiple pairs of non-fixed welds 53, each with two welds 50b arranged at a wide vertical distance GH2 (>GH1), and multiple intermediate welds 50c. The pairs of non-fixed welds 53 are arranged to match the vertical arrangement of the waistline elastic members 23, 33. Therefore, the wide spacing region Rw has multiple (here, two) welds 50b (overlapping welds) that overlap with the weld group 52 in the vertical direction. However, because the spacing GH2 between the pairs of non-fixed welds 53 is wide, the waistline elastic members 23, 33 pass through the pairs of non-fixed welds 53 without being sandwiched between them. The intermediate weld 50c is arranged between the two pairs of non-fixed welds 53 arranged vertically, i.e., at a position where the waistline elastic members 23, 33 are not arranged, and joins the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32.

[0072] Specifically, in the ventral waistline panel 20 ( FIG. 6 ) of this embodiment, the wide-spacing region Rw is the region in the left-right center of the first region R1 where multiple pairs of non-fixed welds 53 are lined up in the up-down and left-right directions (almost the entire area of ​​the first region R1 in the up-down direction). The other regions of the ventral waistline panel 20 where multiple groups of welds 52 are lined up in the up-down and left-right directions are the narrow-spacing region Rn. In the back waistline panel 30 ( FIG. 7 ), the wide-spacing region Rw is the region in the left-right center of the first region R1 and a seventh region R7 (described later) above the first region R1 where multiple pairs of non-fixed welds 53 are lined up in the up-down and left-right directions. The other regions of the back waistline panel 30 where multiple groups of welds 52 are lined up in the up-down and left-right directions are the narrow-spacing region Rn.

[0073] In the region below the waist elastic members 23, 33, i.e., the region where the waist elastic members 23, 33 are not present, a plurality of lower welded portions 50d are arranged at intervals in the vertical and horizontal directions. The lower welded portions 50d join the skin side sheets 21, 31 and the non-skin side sheets 22, 32. The arrangement pattern (area ratio) of the lower welded portions 50d is constant regardless of the first region R1 or the second region R2.

[0074] The area ratio of the welded portions 50 in the wide-gap regions Rw is smaller than the area ratio of the welded portions 50 in the narrow-gap regions Rn. In the diaper 1 of this embodiment, the wide-gap regions Rw are provided in the first region R1 but not in the second region R2. The narrow-gap regions Rn occupy most of the second region R2. Therefore, in the diaper 1, the area ratio of the welded portions 50 in the first region R1 is smaller than the area ratio of the welded portions 50 in the second region R2. Therefore, as described above, the diaper 1 of this embodiment can prevent peeling between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 while suppressing deterioration in wearing comfort and leakage of excrement.

[0075] 6 and 7 are merely examples. The pattern of the welded portions 50 is not limited to the illustrated patterns as long as the area ratio of the welded portions 50 in the first region R1 is smaller than the area ratio of the welded portions 50 in the second region R2.

[0076] Furthermore, in the diaper 1 of this embodiment, both the ventral waist panel 20P and the back waist panel 30P have the first region R1 and the second region R2 that satisfy the above-mentioned relationship of the area ratio of the welded portion 50. However, this is not limiting, and only one of the ventral waist panel 20P and the back waist panel 30P may have the first region R1 and the second region R2 that satisfy the above-mentioned relationship of the area ratio of the welded portion 50, while the other does not.

[0077] Preferably, the plurality of welded portions 50 are arranged at intervals in the vertical direction not only in the first region R1 and the second region R2 but also in other regions of the ventral waistline panel 20P and the back waistline panel 30P. This allows the entire ventral waistline panel 20P and the back waistline panel 30P to deform in the vertical direction along the wearer's body. More preferably, the plurality of welded portions 50 are arranged at intervals not only in the vertical direction but also in the horizontal direction. This allows the ventral waistline panel 20P and the back waistline panel 30P to deform in the horizontal direction along the wearer's body.

[0078] As shown in Fig. 3, the diaper 1 has a display section 60 visible from the non-skin side. Examples of the display section 60 include letters, numbers, symbols, figures, designs, patterns, and combinations thereof. The diaper 1 of this embodiment has a display section 60 with a design depicting a rabbit or a flower, a display section 60 with letters (back) indicating the front or back of the diaper 1, and a display section 60 with letters (L) indicating the size of the diaper 1. The display sections 60 can be printed on the non-skin side of the back sheet 13, the outer sheet 14, the skin-side sheets 21, 31, the non-skin-side sheets 22, 32, or a sheet (not shown) provided between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32, etc.

[0079] When the diaper 1 includes the display section 60, it is preferable that the display section 60 overlaps the first region R1 when the waist panel 20P, 30P is viewed in the thickness direction when the diaper 1 is stretched. In the first region R1, multiple welded sections 50 are vertically distributed. Therefore, even if the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 are not bonded with adhesive, or even if only a small amount of adhesive is used, lifting of the non-skin-side sheets 22, 32 relative to the skin-side sheets 21, 31 can be suppressed. Therefore, the display section 60 in the first region R1 is prevented from reducing visibility due to lifting of the non-skin-side sheets 22, 32. In particular, this prevents a reduction in visibility of the display section 60 printed on the sheet closer to the skin than the non-skin-side sheets 22, 32. Meanwhile, at the welded sections 50, the fibers of the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 melt to form a film. Therefore, the visibility of the display portion 60 overlapping the welded portion 50 is more likely to decrease than that of the display portion 60 not overlapping the welded portion 50. The area ratio of the welded portion 50 in the first region R1 is smaller than that in the second region R2. Therefore, the display portion 60 overlapping the first region R1 is less likely to overlap with the film-formed welded portion 50, and visibility is more likely to be maintained. In other words, in the first region R1, the welded portions 50 are appropriately positioned so that the non-skin side sheets 22, 32 are less likely to lift, and the area ratio of the film-formed welded portion 50 is small, so a decrease in the visibility of the display portion 60 can be suppressed.

[0080] Furthermore, it is preferable that the average strength of the welds 50 in the first region R1 is stronger than the average strength of the welds 50 in the second region R2. This makes it possible to increase the strength of each weld 50, even though the area ratio of the welds 50 in the first region R1 is small. This prevents peeling between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 in the first region R1. This also prevents lifting of the non-skin-side sheets 22, 32, thereby preventing a decrease in the visibility of the display unit 60. The strength of the welds 50 can be varied, for example, by varying the amount of ultrasonic energy applied to the welds 50.

[0081] The average strength of the welded portions 50 in each region (R1, R2) can be compared using a known method. For example, when the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 are joined only by the welded portions 50, a tensile tester (e.g., Instron Model 5965 or equivalent) can be used for comparison. Specifically, the waist panels 20P, 30P are separated from the absorbent main body 10, and the first region R1 and the second region R2 are cut out to prepare samples. The samples are cut from any location in each region R1, R2, measuring 20 mm x 20 mm. If additional sheets are layered in addition to the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32, these sheets are also included in the sample. For each sample, the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 are peeled apart by the width of the zipper grip in a predetermined direction (the left-right or up-down direction of the diaper 1). In addition, the total area A3 of the multiple welds 50 located in the area other than the peeled portion of each sample is obtained. Specifically, a 20 mm x 20 mm sample is observed using a microscope (manufactured by Keyence Corporation) or other microscope, and the number of welds 50 in the area is obtained. Furthermore, 15 welds 50 are randomly selected from the sample, and the average of the areas of the selected welds 50 is defined as the area of ​​one weld 50. In this way, the total area A3 of the welds 50 in the sample is obtained. Next, one chuck of the tensile tester clamps the peeled skin-side sheets 21, 31, and the other chuck clamps the peeled non-skin-side sheets 22, 32. Thereafter, the distance between the pair of chucks is increased at a constant speed (e.g., 100 mm / min) until the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 separate. The maximum tensile load (N) measured during this period is obtained. Then, for each sample, the maximum tensile load is divided by the total area A3 of the multiple welds 50 obtained earlier. The above measurement is performed multiple times (e.g., N = 10), and the average value is calculated for each sample. If the calculated value is greater in the first region R1, it is determined that the average strength of the welds 50 in the first region R1 is greater than that in the second region R2.

[0082] In addition, when the diaper 1 is in an extended state, at least one of the ventral waist panel 20P and the back waist panel 30P (both in this embodiment) has a third region R3 that overlaps with the absorbent main body 10 in the thickness direction, and it is preferable that the area of ​​the welded portions 50 per unit area in the third region R3 is smaller than the area of ​​the welded portions 50 per unit area in the second region R2. In this embodiment, the third region R3 (first region R1) is provided with a wide-gap region Rw, while the second region R2 is not provided with a wide-gap region Rw but is mainly provided with a narrow-gap region Rn.

[0083] This reduces the rigidity of the third region R3, allowing the portion of the absorbent main body 10 overlapping the third region R3 to more easily deform to conform to the wearer's body. As a result, the wearer's comfort is minimized and excrement leakage is reduced. Furthermore, the welded portions 50 are appropriately positioned in the third region R3, preventing lifting of the non-skin-side sheets 22, 32 while reducing the area that is filmed. This minimizes the reduction in visibility of the display unit 60 overlapping the third region R3. Meanwhile, in the second region R2, which is more susceptible to leg pressure, the rigidity is increased, and the bonding area between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 is increased, strengthening the bonding strength between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32. This minimizes peeling between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 in the second region R2.

[0084] 9A and 9B are explanatory diagrams of the third region R3 and the fourth region R4. When the diaper 1 is stretched, at least one of the ventral waist panel 20P and the back waist panel 30P (both in this embodiment) overlaps the absorbent main body 10 in the up-down direction and has a fourth region R4 located in the left-right direction from a position SSi 20 mm inward from the inner end SSe of the side joint SS to the end 10e of the absorbent main body 10. Preferably, the area of ​​the welded portions 50 per unit area in the third region R3 is smaller than the area of ​​the welded portions 50 per unit area in the fourth region R4. In this embodiment, the third region R3 is provided with a wide-spacing region Rw, while the fourth region R4 is provided with no wide-spacing region Rw but mainly with a narrow-spacing region Rn.

[0085] This reduces the rigidity of the third region R3, allowing the portion of the absorbent main body 10 overlapping the third region R3 to more easily deform along the wearer's body. Furthermore, the appropriately positioned welded portions 50 prevent a decrease in the visibility of the display unit 60 overlapping the third region R3. Meanwhile, the fourth region R4 abuts the area inside the wearer's waist, more easily deformed by the wearer's leg movements. Therefore, the rigidity is increased in the fourth region R4, and the bonding area between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 is increased, thereby strengthening the bonding strength between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32. This prevents peeling between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 in the fourth region R4. Furthermore, the fourth region R4 is longer in the left-right direction than the second region R2. Therefore, according to the above, peeling between the skin side sheets 21, 31 and the non-skin side sheets 22, 32 can be suppressed over a wide range of the waist panels 20P, 30P in the left-right direction.

[0086] 10A and 10B are explanatory diagrams of the first region R1 and the fifth region R5. When the diaper 1 is stretched, at least one of the ventral waist panel 20P and the back waist panel 30P (both in this embodiment) overlaps the absorbent core 11 in the up-down direction and has a fifth region R5 located in the left-right direction from the end 11e of the absorbent core 11 to the ends 20e, 30e of the one waist panel 20P, 30P. Preferably, the area of ​​the welded portions 50 per unit area in the first region R1 is smaller than the area of ​​the welded portions 50 per unit area in the fifth region R5. In this embodiment, the first region R1 is provided with a wide-spacing region Rw, while the fifth region R5 is not provided with a wide-spacing region Rw but is mainly provided with a narrow-spacing region Rn.

[0087] This reduces the rigidity of the first region R1, allowing the portion of the absorbent core 11 overlapping the first region R1 to deform more easily to conform to the wearer's body. Furthermore, the appropriately positioned welded portions 50 prevent a decrease in the visibility of the display unit 60 overlapping the first region R1. Meanwhile, the fifth region R5 is an area affected by the wearer's leg movement. Therefore, the fifth region R5 has increased rigidity and the bonding area between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 is increased, thereby strengthening the bonding strength between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32. This prevents peeling between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 in the fifth region R5. Furthermore, peeling between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 can be prevented over a wide range of the waistband panels 20P, 30P in the left-right direction. In addition, when the side joints SS are formed by welded parts, the welded parts that form the side joints SS also correspond to the welded parts that join the skin side sheets 21, 31 and the non-skin side sheets 22, 32.

[0088] 11A and 11B are explanatory diagrams of the first region R1 and the sixth to eighth regions R6 to R8. When the diaper 1 is stretched, at least one of the ventral waist panel 20P and the back waist panel 30P (both in this embodiment) overlaps with the absorbent main body 10 in the left-right direction and has a sixth region R6 located in a range from the upper end of the absorbent main body 10 to the upper ends of the waist panels 20P and 30P. In this case, the area of ​​the welded portions 50 per unit area in the sixth region R6 is preferably larger than the area of ​​the welded portions 50 per unit area in the first region R1. In this embodiment, the first region R1 is provided with a wide-gap region Rw, while the sixth region R6 is not provided with a wide-gap region Rw but is mainly provided with a narrow-gap region Rn.

[0089] This reduces the rigidity of the first region R1, allowing the portion of the absorbent core 11 overlapping the first region R1 to more easily deform to conform to the wearer's body. Furthermore, the appropriately positioned welded portions 50 prevent a decrease in the visibility of the indicator 60 overlapping the first region R1. Meanwhile, the sixth region R6 is the upper end of the waist panels 20P, 30P, which is the region that is grasped by the user (e.g., parent) when pulling up the diaper 1. Therefore, increasing the rigidity of the sixth region R6 makes it easier for the user to grasp the upper end of the waist panels 20P, 30P. Furthermore, the shape of the upper end of the waist panels 20P, 30P is more easily maintained even while the diaper 1 is being worn. This prevents the upper end of the waist panels 20P, 30P from curling (making them less likely to wrinkle).

[0090] Furthermore, when the diaper 1 is in an extended state, at least one of the ventral waist panel 20P and the back waist panel 30P (both in this embodiment) overlaps with the absorbent main body 10 in the left-right direction and has a seventh region R7 located in a range from the upper end of the absorbent core 11 to the upper end of the absorbent main body 10. In this case, the area of ​​the welded portions 50 per unit area in the seventh region R7 is preferably larger than the area of ​​the welded portions 50 per unit area in the first region R1. In this embodiment, the first region R1 is provided with a wide-gap region Rw, while the seventh region R7 is not provided with a wide-gap region Rw but is mainly provided with a narrow-gap region Rn.

[0091] This reduces the rigidity of the first region R1, allowing the portion of the absorbent core 11 overlapping the first region R1 to more easily deform along the wearer's body. Furthermore, the appropriately positioned welded portions 50 can prevent a decrease in the visibility of the indicator 60 overlapping the first region R1. Meanwhile, increasing the rigidity of the seventh region R7 efficiently transfers the pulling force from the upper ends of the waist panels 20P, 30P to the upper end of the absorbent main body 10. This makes it easier to pull up the diaper 1 when putting it on and prevents it from slipping down while wearing it.

[0092] Furthermore, when the diaper 1 is stretched, at least one of the ventral waist panel 20P and the back waist panel 30P (both in this embodiment) overlaps with the absorbent main body 10 in the up-down direction and has an eighth region R8 located in the left-right direction from the end 11e of the absorbent core 11 to the end 10e of the absorbent main body 10. In this case, the area of ​​the welded portions 50 per unit area in the first region R1 is preferably smaller than the area of ​​the welded portions 50 per unit area in the eighth region R8. In this embodiment, the first region R1 is provided with a wide-gap region Rw, while the eighth region R8 is not provided with a wide-gap region Rw but is mainly provided with a narrow-gap region Rn.

[0093] By doing so, it is possible to further reduce the rigidity of the first region R1 overlapping the absorbent core 11 within the third region R3 overlapping the absorbent main body 10. This makes it easier for the absorbent core 11 to deform along the wearer's body, which can lead to leakage, and makes it less likely for gaps to form between the absorbent core 11 and the wearer. In addition, the appropriately positioned welded portions 50 can prevent a decrease in visibility of the display unit 60 overlapping the first region R1.

[0094] Furthermore, when the diaper 1 is in an extended state, it is preferable that at least one of the ventral waist panel 20P and the dorsal waist panel 30P (in this embodiment, both) has the following characteristics: The area of ​​the welded portion 50 per unit area in the first region R1 is preferably smaller than the area of ​​the welded portion 50 per unit area in the third region R3 that does not include the first region R1.

[0095] This allows the rigidity of the first region R1 to be further reduced. This allows the absorbent core 11, which is more likely to leak, to deform along the wearer's body, reducing the likelihood of gaps forming between the absorbent core and the wearer. Furthermore, the area of ​​the third region R3 that does not include the first region R1 overlaps the outer edge of the absorbent main body 10 and is affected by the wearer's movements (leg movements and waist movements). This increases the rigidity of this region, and the bonding area between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 increases, thereby increasing the bonding strength. This prevents the skin-side sheets 21, 31 from peeling from the non-skin-side sheets 22, 32 in this region.

[0096] Furthermore, the contractile force in the left-right direction of the first region R1 is preferably weaker than that of the fifth region R5 (FIGS. 10A and 10B). The contractile force is the force that causes each region R1, R5 to return to its original length from an elongated state. As shown in FIGS. 6 and 7 , the first region R1 of this embodiment has a non-stretchable region NE in the left-right direction where the stretchable portions of the waist elastic members 23, 33 are not present and are discontinuous. On the other hand, the majority of the fifth region R5 (excluding the left-right ends) has the stretchable portions of the waist elastic members 23, 33, forming a stretchable region E where stretchability is exhibited. Therefore, the contractile force in the left-right direction of the first region R1 is weaker than that of the fifth region R5. Alternatively, the entire first region R1 may be a non-stretchable region NE, and the contractile force (stretching force) of the first region R1 may be zero.

[0097] As described above, the contraction (crease formation) in the left-right direction of the absorbent core 11 overlapping the first region R1 can be suppressed. This reduces discomfort when worn, reduces the likelihood of gaps forming between the absorbent core 11 and the wearer, and suppresses leakage of body waste. Furthermore, the visibility of the indicator 60 overlapping the first region R1 can be prevented from being reduced due to wrinkles in the absorbent core 11. Meanwhile, the fifth region R5 is located outside the absorbent main body 10 in the left-right direction and contacts the wearer's legs. Therefore, the large contractile force of the fifth region R5 allows the fifth region R5 to more easily follow the movement of the wearer's legs, maintaining a good fit and suppressing a decrease in comfort.

[0098] The contractile forces of the first region R1 and the fifth region R5 can be compared using a known method. For example, a tensile tester (e.g., Instron Model 5965 or equivalent) can be used for the comparison. Specifically, the waist panels 20P and 30P are separated from the absorbent main body 10, and the first region R1 and the fifth region R5 are cut out to prepare samples. The samples are cut out from any location in each region R1 and R5, measuring 20 mm x 20 mm. Both ends of the sample in the stretch direction (left and right direction of the diaper 1) are clamped between a pair of chucks of the tensile tester. The initial spacing between the pair of chucks is adjusted to a length that does not sag the sample or causes it to sag slightly. Next, the spacing between the pair of chucks is increased in the stretch direction of the sample at a predetermined speed (e.g., 100 mm / min). The sample is then stretched until it reaches a predetermined stretch state (e.g., 90% stretch state) when the maximum stretch of the sample is 100%. The distance between the pair of chucks is then reduced at a predetermined speed (e.g., 100 mm / min) until the sample is stretched from a predetermined stretched state (e.g., 90%) to a lower stretched state (e.g., 70%). The contractile force (N) is determined by measuring the contractile force at an intermediate stretched state (e.g., 80%) when the sample is stretched from the predetermined stretched state (e.g., 90%) to a lower stretched state (e.g., 70%). The above measurement is performed multiple times (e.g., N = 10), and the average contractile force (N) calculated for each sample is compared.

[0099] Furthermore, the group of welds 52 (see FIG. 8 ) in the narrow spacing region Rn fixes the positions of the waistline elastic members 23, 33. As shown in FIGS. 6 and 7 , the group of welds 52 in the narrow spacing region Rn (welded portions that fix the positions of the thread-like elastic members) is provided in the second region R2. Meanwhile, the wide spacing region Rw is provided in the center of the first region R1 in the left-right direction, and the group of welds 52 in the narrow spacing region Rn (welded portions that fix the positions of the thread-like elastic members) is not provided.

[0100] Therefore, a non-stretchable region NE, where the waist elastic members 23, 33 are not present, can be formed in the left-right center of the first region R1. This prevents the absorbent core 11 from shrinking in the left-right direction (crease formation) in the absorbent core 11 that overlaps the first region R1. This prevents a decrease in comfort and leakage of body waste. Furthermore, it also prevents a decrease in visibility of the display unit 60 that overlaps the first region R1.

[0101] The provision of the wide-spacing region Rw in the horizontal center of the first region R1 means that the wide-spacing region Rw is provided across the horizontal center of the first region R1. Preferably, the wide-spacing region Rw is provided over at least one-quarter of the horizontal length of the first region R1, and more preferably, the wide-spacing region Rw is provided over at least one-third of the horizontal length of the first region R1. This reduces the contractile force of the first region R1 and suppresses contraction of the absorbent core 11. Furthermore, the wide-spacing region Rw may be provided in at least a portion of the vertical region of the first region R1 where the waist elastic members 23, 33 are arranged. Preferably, as in this embodiment, the wide-spacing region Rw is provided over the entire vertical region of the first region R1 where the waist elastic members 23, 33 are arranged. This suppresses contraction of the absorbent core 11 over a wide range of the absorbent core 11 in the vertical direction.

[0102] On the other hand, in the second region R2, where the wearer's legs are likely to exert force, a stretchable region E can be formed, where the stretchable portions of the waist elastic members 23, 33 are present. Therefore, the second region R2 can more easily follow the movement of the wearer's legs, maintaining a good fit and preventing a decrease in comfort. Furthermore, by fixing the waist elastic members 23, 33 with the welded portions 52, stretchability can be imparted to the second region R2 without using adhesive or with a reduced amount of adhesive. This prevents a decrease in flexibility in the second region R2 due to hardening of the adhesive and a decrease in the elastic properties of the waist elastic members 23, 33. Therefore, compared to when the waist elastic members 22, 33 are fixed to the sheet with adhesive or the like, the waist elastic members 22, 33 are more flexible in contracting due to leg movement, making the waist panels 20, 30 less likely to break.

[0103] Furthermore, in the waist panels 20P, 30P of this embodiment, a narrow-interval region Rn is provided in the first region R1 except for the central portion in the left-right direction. That is, the waist elastic members 23, 33 are fixed by the welded portions 52 throughout the entire stretchable region E of the waist panels 20P, 30P. Therefore, throughout the entire stretchable region E of the waist panels 20P, 30P, it is possible to suppress a decrease in flexibility due to hardening of the adhesive and a decrease in the elastic properties of the waist elastic members 23, 33.

[0104] Furthermore, the welded portions 50 that fix the positions of the waistline elastic members 23, 33 are not limited to the two welded portions 50 in the welded portion group 52 as in this embodiment. For example, the welded portions 50 may overlap the waistline elastic members 23, 33 in the thickness direction. In other words, the welded portions 50 may be formed by welding the waistline elastic members 23, 33 together with the skin side sheets 21, 31 and the non-skin side sheets 22, 32.

[0105] However, as in the present embodiment, in the second region R2, it is preferable that the waist elastic members 23, 33 be sandwiched between two vertically adjacent welds 50 in the weld group 52 (see FIG. 8 ), thereby fixing the positions of the waist elastic members 23, 33. This makes it less likely that the waist elastic members 23, 33 will be unnecessarily cut during the formation of the welds 50 or while the diaper 1 is being worn, compared to when the waist elastic members 23, 33 overlap the welds 50 in the thickness direction. This more reliably imparts stretchability to the second region R2, making it easier to maintain that stretchability. Furthermore, the two upper and lower welds 50 sandwiching the waist elastic members 23, 33 are located within the weld group 52. This increases the bond strength between the skin-side sheets 21, 31 and the non-skin-side sheets 22, 32 around the two welds 50 sandwiching the waist elastic members 23, 33. Therefore, even if excessive tension is applied to the waist elastic members 23, 33, peeling of the welded portions 50 sandwiching the waist elastic members 23, 33 can be suppressed.

[0106] The number of welded portions 50a constituting the welded portion group 52 need only be two or more, and is not limited to six. However, it is preferable that three or more welded portions 50a are arranged vertically. In this case, even if there is a deviation in the formation position of the welded portion 50 or the arrangement of the waist elastic members 23, 33, any two welded portions 50 in the welded portion group 52 can fix the positions of the waist elastic members 23, 33.

[0107] Furthermore, not only in the second region R2 but also in other regions of the waist panels 20P, 30P, it is preferable that the waist elastic members 23, 33 are fixed in position by being sandwiched between two vertically adjacent welded portions 50. This makes it difficult for the waist elastic members 23, 33 to be unnecessarily cut, and allows the waist panels 20P, 30P to have stretchability that is easily maintained.

[0108] Furthermore, when the diaper 1 is stretched, the first region R1 has non-fixed weld pairs 53 (plurality of overlapping welds 50b) that overlap in the vertical direction with the weld group 52. Note that "overlapping in the vertical direction with the weld group 52" refers to welds 50 (non-fixed weld pairs 53) that overlap the range from the top end of the uppermost weld 50 to the bottom end of the lowermost weld 50 in the weld group 52. In this case, the minimum vertical spacing GH2 between the non-fixed weld pairs 53 (the minimum vertical spacing between two vertically adjacent overlapping welds 50b) is preferably wider than the minimum vertical spacing GH1 between two vertically adjacent welds 50 in the weld group 52 (GH2 > GH1).

[0109] By doing so, in the first region R1, the waist elastic members 23, 33 pass through between the pairs of non-fixed welded portions 53, forming a non-stretched region NE where there are no stretched portions of the waist elastic members 23, 33. This suppresses contraction of the absorbent core 11, thereby suppressing deterioration in comfort and reducing leakage of body waste. Furthermore, because the spacing between the welded portions 50 in the vertical direction is wider, the area ratio of the welded portions 50 in the first region R1 can be made smaller than the area ratio of the welded portions 50 in the second region R2.

[0110] However, as shown in Figures 6 and 7, at both lateral ends of the first region R1, the waist elastic members 23, 33 are preferably sandwiched between two vertically adjacent welded portions 50, thereby fixing the positions of the waist elastic members 23, 33. In other words, narrow-spaced regions Rn (groups of welded portions 52) are preferably provided at both lateral ends of the first region R1. This allows the waist elastic members 23, 33 to exhibit stretchability in areas overlapping with both lateral ends of the absorbent core 11. This allows both lateral ends of the absorbent core 11 to fit the wearer's body, preventing misalignment of the absorbent core 11. This reduces leakage of body waste. Furthermore, if the waist elastic members 23, 33 in the first region R1 are cut to further reduce the stress on the absorbent core 11, the cut ends of the waist elastic members 23, 33 will contract in the lateral direction due to retraction stress. In this case, too, by restricting the positions of the waist elastic members 23, 33 at both ends of the first region R1, it is possible to prevent a decrease in the stress of the waist elastic members 23, 33 in the region that is laterally outward of the first region R1 and is affected by the movement of the wearer's legs. However, this is not limited to the above, and the entire laterally inward area of ​​the first region R1 may be the non-stretchable region N.

[0111] Furthermore, when the non-skin-side sheet 32 ​​of the rear waist panel 30P is made of a nonwoven fabric and the post-treatment tape 70 is bonded to the non-skin-side sheet 32 ​​with an adhesive (not shown), it is preferable that the rear first region R1 has a portion that overlaps with the post-treatment tape 70 in the thickness direction when the diaper 1 is in an extended state (FIG. 3).

[0112] As described above, the area ratio of the welded portion 50 is small in the first region R1. In other words, the area of ​​the region (welded portion 50) where the fibers of the non-skin-side sheet 32 ​​are melted and turned into a film by welding is small. This allows the adhesive used to bond the post-treatment tape 70 to the back waist panel 30 to easily penetrate the fibers of the non-skin-side sheet 32 ​​(nonwoven fabric), increasing the adhesive bonding strength of the post-treatment tape 70. This makes it difficult for the post-treatment tape 70 to separate from the back waist panel 30 even when the diaper 1 rubs against clothing during wear. This maintains the bonded state of the post-treatment tape 70 even when the diaper 1 is disposed of, allowing the diaper 1 to be disposed of compactly using the post-treatment tape 70.

[0113] In the diaper 1 of this embodiment, the ventral waist panel 20P and the back waist panel 30P each have a first region R1 and a second region R2, and the area ratio of the welded portions 50 in the first region R1 is smaller than that in the second region R2. In this case, it is preferable that the area of ​​the welded portions 50 per unit area be different between the back-side first region R1 and the ventral-side first region R1.

[0114] In the diaper 1 of this embodiment, the width of the wide-gap region Rw provided in the back-side first region R1 ( FIG. 7 ) is longer than the width of the wide-gap region Rw provided in the ventral-side first region R1 ( FIG. 6 ). Therefore, the area ratio of the welded portions 50 in the back-side first region R1 is smaller than the area ratio of the welded portions 50 in the ventral-side first region R1. In this case, the area of ​​the welded film-like region (welded portions 50) in the back-side first region R1 is smaller. This increases the bonding strength of the post-treatment tape 70 in the first region R1.

[0115] Conversely, although not shown, the area ratio of the welded portions 50 in the back-side first region R1 may be greater than the area ratio of the welded portions 50 in the ventral first region R1. In this case, the bonding area between the skin-side sheet 31 and the non-skin-side sheet 32 ​​in the back-side first region R1 is larger. Therefore, even if the back-side waistline panel 30P rubs against each other when the wearer is lying down, peeling between the skin-side sheet 31 and the non-skin-side sheet 32 ​​in the back-side waistline panel 30P can be suppressed. Furthermore, since the area ratio of the welded portions 50 in the ventral first region R1 is smaller, the rigidity of the ventral first region R1 is further reduced. Therefore, the feeling of tightness can be reduced even when the lower abdomen moves due to the wearer's breathing. However, the above is not limiting, and the area ratio of the welded portions 50 in the back-side first region R1 and the ventral first region R1 may be the same.

[0116] Fig. 12 is a partial enlarged view of the first region R1 and the second region R2. Fig. 13 shows a modified pattern of the welded portions 50. When the diaper 1 is stretched, the spacing W2 between adjacent welded portions 50 in the left-right direction in the first region R1 is preferably greater than the left-right length W3 of each adjacent welded portion 50 (W2 > W3). This increases the spacing W2 between the welded portions 50 in the left-right direction in the first region R1, allowing the multiple welded portions 50 to be dispersed in the left-right direction and reducing the area ratio of the welded portions 50. This makes the first region R1 more susceptible to deformation in the left-right direction, reduces the rigidity of the first region R1, and allows the absorbent core 11 to more easily conform to the wearer's body.

[0117] Furthermore, in the first region R1, the plurality of welds 50 are arranged at intervals in the left-right direction. In this case, it is preferable that the interval W2 between adjacent welds 50 in the left-right direction is constant when the diaper 1 is in an extended state, as shown in Figures 6, 7, and 12. This allows the welds 50 to be evenly distributed in the left-right direction in the first region R1. This allows the first region R1 to easily deform in the left-right direction over a wide range in the left-right direction, and the absorbent core 11 to easily conform to the wearer's body.

[0118] Furthermore, it is also preferable that the spacing W2 between adjacent welded portions 50 in the left-right direction is constant in the third region R3 overlapping the absorbent main body 10. This allows the welded portions 50 to be evenly distributed in the left-right direction in the third region R3 as well. This makes it easier for the third region R3 to deform in the left-right direction over a wide range in the left-right direction, and makes it easier for the absorbent main body 10 to conform to the wearer's body.

[0119] Furthermore, it is preferable that the plurality of welded portions 50 are arranged at intervals in the left-right direction even on the outer side of the absorbent main body 10 (for example, in the second region R2 or the fourth region R4), and that the intervals W2 are constant. This allows the welded portions 50 to be evenly distributed in the left-right direction even on the waist panels 20P, 30P on the outer side of the absorbent main body 10. This makes it easier for the waist panels 20P, 30P on the outer side of the absorbent main body 10 to deform in the left-right direction, allowing them to conform to the wearer's body and follow the movement of the legs. Furthermore, in the waist panels 20P, 30P on the outer side of the absorbent main body 10, the sheet between the welded portions 50 shrinks, forming certain wrinkles, improving the appearance of the diaper 1.

[0120] Furthermore, it is preferable that the left-right spacing W2 between the welded portions 50 in the first region R1 and the third region R3 and the left-right spacing W2 between the welded portions 50 on the left-right outer side of the absorbent main body 10 are constant. This makes it easier for the waist panels 20P, 30P to deform in the left-right direction over almost the entire left-right area, and to fit the wearer's body more easily.

[0121] However, the spacing W2 between the welded portions 50 arranged in the left-right direction need not be constant. For example, if a wide-spacing region Rw is provided in the first region R1 and the waist elastic members 23, 33 are cut in the wide-spacing region Rw, the welded portions 50 may be arranged as shown in FIG. 13 . That is, in the narrow-spacing region RN on the left-right outer side of the first region R1 (wide-spacing region Rw), the spacing W4 between the welded portions 50 (groups of welded portions 52) in the left-right direction may be narrower than the spacing W2 between the welded portions 50 in other regions. This ensures that the cut pieces of the waist elastic members 23, 33 are more securely sandwiched between the groups of welded portions 52 arranged at the narrow spacing W4 in the left-right direction during manufacture and wear of the diaper 1. This prevents the waist elastic members 23, 33 from slipping off, imparting stretchability to the waist panels 20P, 30P, and maintaining that stretchability. As shown in Figure 13, when the group of welded portions 52 in the eighth region R8 are arranged at a narrow interval W4 in the left-right direction, the area of ​​the welded portions 50 per unit area in the first region R1 is smaller than the area of ​​the welded portions 50 per unit area in the eighth region R8.

[0122] Furthermore, although not shown, the left-right spacing of the welds 50 (group of welds 52) near the side joints SS (for example, within a range of about 20 mm inward from the inner end SSe of the side joints SS) may be narrower than the spacing W2 of the welds 50 in other regions. By doing so, even if the waist elastic members 23, 33 are unnecessarily cut when forming the side joints SS or while wearing the garment, the waist elastic members 23, 33 are sandwiched between the group of welds 52 that are arranged at a narrow left-right interval. This allows the waist panels 20P, 30P to be stretchable and maintain that stretchability.

[0123] Although the embodiments of the present invention have been described above, the above embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Furthermore, 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.

[0124] REFERENCE SIGNS LIST 1 pants-type disposable diaper (absorbent article), 2 leakage-barrier wall portion, 10 absorbent main body, 11 absorbent core, 12 top sheet, 13 back sheet, 14 outer sheet, 20 ventral side outer member, 20P ventral side waist panel, 21 skin-side sheet, 22 non-skin-side sheet, 23 waist elastic member (elastic member), 30 dorsal side outer member, 30P dorsal side waist panel, 31 skin-side sheet, 32 non-skin-side sheet, 33 waist elastic member (elastic member), 50 welded portion, 51 welded portion pair, 52 welded portion group, 53 non-fixed welded portion pair, 60 indication portion, 70 post-treatment tape

Claims

1. An absorbent article having an absorbent main body having an absorbent core and vertical and horizontal directions perpendicular to each other, a ventral waist panel on the ventral side, and a back waist panel on the back side, wherein at least one of the ventral waist panel and the back waist panel has an elastic member, a skin-side sheet arranged closer to the skin than the elastic member, and a non-skin-side sheet arranged closer to the skin than the elastic member, the skin-side sheet and the non-skin-side sheet being joined by a plurality of welds, and when the absorbent article is stretched, the one waist panel has: a first region overlapping the absorbent core in the vertical and horizontal directions; and a second region overlapping with the absorbent main body in the vertical direction and located in a range from a center position between an end of the absorbent main body and an end of the one waist panel to the end of the absorbent main body in the horizontal direction, and the plurality of welds are arranged at intervals in the vertical direction in the first region and the second region, An absorbent article, characterized in that the area of ​​the welded portions per unit area in the first region is smaller than the area of ​​the welded portions per unit area in the second region.

2. An absorbent article as described in claim 1, wherein, in a stretched state of the absorbent article, one of the waist panels has a third region that overlaps with the absorbent main body when viewed in the thickness direction, and the area of ​​the welded portion per unit area in the third region is smaller than the area of ​​the welded portion per unit area in the second region.

3. An absorbent article as claimed in claim 1 or 2, wherein the ventral waist panel and the dorsal waist panel are joined to each other by a pair of side joints at both ends in the left-right direction, and when the absorbent article is in a stretched state, one of the waist panels has: a third region that overlaps with the absorbent main body when viewed in the thickness direction; and a fourth region that overlaps with the absorbent main body in the up-down direction and is located in a range from a position 20 mm inward from the inner edge of the side joint to the edge of the absorbent main body in the left-right direction, and wherein the area of ​​the welded portion per unit area in the third region is smaller than the area of ​​the welded portion per unit area in the fourth region.

4. An absorbent article as claimed in claim 1 or 2, characterized in that it has a display part that is visible from the non-skin side, and when the absorbent article is in a stretched state, when the one waist panel is viewed in the thickness direction, the display part has a portion that overlaps with the first region.

5. An absorbent article as claimed in claim 1 or 2, wherein, in a stretched state of the absorbent article, one of the waist panels has a fifth region that overlaps with the absorbent core in the vertical direction and is located in a range from the edge of the absorbent core to the edge of one of the waist panels in the horizontal direction, and the area of ​​the welded portion per unit area in the first region is smaller than the area of ​​the welded portion per unit area in the fifth region.

6. An absorbent article as claimed in claim 1 or 2, wherein, in a stretched state of the absorbent article, one of the waist panels has a sixth region that overlaps with the absorbent main body in the left-right direction and is located in a range from the upper end of the absorbent main body to the upper end of one of the waist panels, and the area of ​​the welded portion per unit area in the sixth region is larger than the area of ​​the welded portion per unit area in the first region.

7. An absorbent article as described in claim 1 or 2, wherein, in a stretched state of the absorbent article, one of the waist panels has a seventh region that overlaps with the absorbent main body in the left-right direction and is located in a range from the upper end of the absorbent core to the upper end of the absorbent main body, and the area of ​​the welded portion per unit area in the seventh region is larger than the area of ​​the welded portion per unit area in the first region.

8. An absorbent article as described in claim 1 or 2, wherein, in a stretched state of the absorbent article, one of the waist panels has an eighth region that overlaps with the absorbent main body in the vertical direction and is located in a range from the end of the absorbent core to the end of the absorbent main body in the horizontal direction, and the area of ​​the welded portion per unit area in the first region is smaller than the area of ​​the welded portion per unit area in the eighth region.

9. An absorbent article according to claim 1 or 2, characterized in that the average strength of the welded portions in the first region is greater than the average strength of the welded portions in the second region.

10. An absorbent article according to claim 5, characterized in that the contractile force in the left-right direction of the first region is weaker than the contractile force in the left-right direction of the fifth region.

11. An absorbent article as claimed in claim 1 or 2, characterized in that the elastic member is a thread-like elastic member, the welded portion for fixing the position of the elastic member is provided in the second region, and the welded portion for fixing the position of the elastic member is not provided in the central portion in the left-right direction of the first region.

12. An absorbent article as claimed in claim 1 or 2, wherein the elastic member is a thread-like elastic member, and when the absorbent article is in a stretched state, the second region has a group of welded portions in which a plurality of the welded portions are lined up in the vertical direction, and in the second region, the position of the elastic member is fixed by being sandwiched between two of the group of welded portions that are adjacent in the vertical direction, and the first region has a plurality of overlapping welded portions that are welded portions that overlap with the group of welded portions in the vertical direction, and the minimum vertical distance between two overlapping welded portions that are adjacent in the vertical direction is wider than the minimum vertical distance between two of the group of welded portions that are adjacent in the vertical direction.

13. An absorbent article as described in claim 12, characterized in that the position of the elastic member is fixed at both left and right ends of the first region by being sandwiched between two of the welded portions adjacent to each other in the up and down direction.

14. An absorbent article as claimed in claim 1 or 2, wherein the rear waist panel has the first region and the second region, the non-skin side sheet of the rear waist panel is a nonwoven fabric, and a post-treatment tape is bonded to the non-skin side sheet with an adhesive, and when the absorbent article is in a stretched state, the first region on the rear side has a portion that overlaps with the post-treatment tape when viewed in the thickness direction.

15. An absorbent article according to claim 14, wherein the ventral waist panel and the dorsal waist panel each have the first region and the second region, and the area of ​​the welded portion per unit area is different between the dorsal first region and the ventral first region.

16. An absorbent article as described in claim 1 or 2, characterized in that, when the absorbent article is in a stretched state, the distance between adjacent welded portions in the left-right direction in the first region is greater than the length of each of the adjacent welded portions in the left-right direction.

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