Product group of disposable diaper

Abstract

Provided is a product group of a disposable diaper with which it is hard to catch an inner thigh in a leg opening and the abdomen can be sufficiently covered when wearing the disposable diaper. In a disposable diaper having adjacent sizes among a plurality of types of disposable diapers (1), a length (LLC) of an absorbent body (4) in the longitudinal direction of a crotch region (4a) that does not overlap a ventral part (3) and a dorsal part (2) is larger for a disposable diaper having a large size than a disposable diaper having a small size. The amount of increase in the length (LAx1, LBx1) in the longitudinal direction from a main body non-existing region (AX1, BX1) of the disposable diaper having a small size to the main body non-existing region of the disposable diaper having a large size is set such that the rate of increase represented by the following equation is in the range of 4.1-39.4%. Rate of increase (%) = (amount of increase) (length LLO in the longitudinal direction in the expanded state of the disposable diaper having a large size) × 100.

Description

Disposable diaper product range

[0001] The present invention relates to disposable diapers, and more particularly to a group of disposable diaper products consisting of a plurality of types of disposable diapers of different sizes.

[0002] Disposable diaper product groups consisting of multiple types of disposable diapers of different sizes are known. For example, Patent Literature 1 discloses an array of products including three or more different sizes of disposable pant-type absorbent articles. The array includes a first package including a plurality of first disposable pant-type absorbent articles, a second package including a plurality of second disposable pant-type absorbent articles, and a third package including a plurality of third disposable pant-type absorbent articles. Each of the first disposable pant-type absorbent article, the second disposable pant-type absorbent article, and the third disposable pant-type absorbent article includes a chassis having a front portion and a rear portion and an absorbent body attached to the chassis. The front and rear portions of the first disposable pant-type absorbent article are smaller in size than the front and rear portions of the second disposable pant-type absorbent article, and the front and rear portions of the third disposable pant-type absorbent article are larger in size than the front and rear portions of the second disposable pant-type absorbent article. Each of the front and rear portions has a waist edge, a pair of leg edges, and a pair of side edges. When the disposable pant-type absorbent articles are in a fully stretched state, the distance in the length direction between the leg edges of the front portion and the leg edges of the rear portion is common to all the disposable pant-type absorbent articles in the array of packages, and the distance is measured along one of the side edges.

[0003] Japanese Patent Application Laid-Open No. 2019-536549

[0004] Patent Document 1 discloses a product group consisting of three types of disposable diapers (pants-type absorbent articles) of different sizes. These three types of disposable diapers have different sizes for the ventral portion (front portion) covering the wearer's ventral side and the posterior portion (rear portion) covering the wearer's posterior side. However, the length of the crotch portion between the ventral portion and the posterior portion is the same for these three types of disposable diapers, and the size of the absorbent body is also the same for these three types of disposable diapers. Therefore, despite the different sizes, the opening diameters of the leg openings of the three types of disposable diapers are approximately the same. As the wearer's body grows, the circumference of the legs also increases. Therefore, when changing the size of a disposable diaper from a smaller size to a larger size and putting it on a child, when the disposable diaper is pulled up by inserting the child's legs into the leg openings, the child's inner thighs tend to get caught in the leg openings. This makes it difficult to pull up the disposable diaper to a sufficient height, and there is a risk that the abdomen will not be sufficiently covered (the navel will be easily exposed) even after changing the size of the disposable diaper to a larger size.

[0005] To provide a disposable diaper product group consisting of a plurality of types of disposable diapers of different sizes, which can prevent the inner thighs of a child from getting caught in the leg openings and can sufficiently cover the abdomen of a child when the size of the disposable diaper is changed from small to large according to the growth of the body and the child wears the diaper.

[0006] The disposable diaper product group of the present invention is a disposable diaper product group consisting of a plurality of types of disposable diapers of different sizes, each of which has, in an unfolded state, longitudinal, width and thickness directions which are orthogonal to one another, a abdominal portion covering the abdominal side of a wearer, a back portion covering the back side, and an absorbent main body covering the crotch of the wearer and including an absorbent body, and the front and back ends of the absorbent main body in the longitudinal direction are connected to central portions in the width direction of the abdominal portion and the back portion, respectively, and are formed by joining both side edges in the width direction of the abdominal portion and both side edges in the width direction of the back portion with a pair of side joining portions, and each of the abdominal portion and the back portion has, in the longitudinal direction, a main body existence region in which the absorbent main body is present and a main body existence region in which the main body is present. and a main body absent region where the absorbent main body is not present, wherein, in adjacent sizes of disposable diapers among the plurality of types of disposable diapers, the longitudinal length of the crotch region that does not overlap the ventral side region and the dorsal side region of the absorbent main body is longer in the larger size disposable diaper than in the smaller size disposable diaper, and the increase in the longitudinal length from the main body absent region of the smaller size disposable diaper to the main body absent region of the larger size disposable diaper is set so that the increase rate, as expressed by the following formula, is in the range of 4.1 to 39.4%: increase rate (%) = (the increase amount) / (the longitudinal length of the large size disposable diaper in the unfolded state) x 100.

[0007] According to the present invention, it is possible to provide a disposable diaper product group consisting of a plurality of types of disposable diapers of different sizes, in which when a child changes the size of the disposable diaper from smaller to larger as the child grows, the child's inner thighs are less likely to get caught in the leg openings and the child's abdomen is sufficiently covered.

[0008] 1 is a perspective view showing an example of a configuration of a disposable diaper according to an embodiment; FIG. 2 is a plan view of the example of a configuration of a disposable diaper according to an embodiment in an unfolded state; FIG. 3 is a cross-sectional view taken along the longitudinal center line CL in FIG. 2; FIG. 4 is a cross-sectional view taken along the widthwise center line CW in FIG. 2; FIG. 5 is a partial plan view of the example of a configuration of a disposable diaper according to an embodiment in an unfolded state; FIG. 6 is a plan view of the example of a configuration of a disposable diaper according to an embodiment in an unfolded state; FIG. 7 is a plan view of the example of a configuration of a disposable diaper according to an embodiment in an unfolded state; FIG. 8 is a partial side view of the example of a configuration of a disposable diaper according to an embodiment; FIG. 9 is a partial plan view of the example of a configuration of a disposable diaper according to an embodiment in an unfolded state; FIG. 10 is a perspective view showing a state in which the disposable diaper according to an embodiment is worn; FIG. 11 is a schematic view showing an example of a method for manufacturing a disposable diaper according to an embodiment.

[0009] The present embodiment relates to the following aspects.

[0010] [Aspect 1] A disposable diaper product group consisting of a plurality of types of disposable diapers of different sizes, each of which, in an unfolded state, has a longitudinal direction, a width direction, and a thickness direction that are orthogonal to one another, and is provided with a abdominal portion covering the abdominal side of a wearer, a dorsal portion covering the dorsal side, and an absorbent main body covering the crotch of the wearer and including an absorbent body, and the front and rear ends of the absorbent main body in the longitudinal direction are connected to central portions in the width direction of the abdominal portion and the dorsal portion, respectively, and are formed by joining both side edges in the width direction of the abdominal portion and both side edges in the width direction of the dorsal portion with a pair of side joining portions, and each of the abdominal portion and the dorsal portion has a main body presence region in which the absorbent main body is present and a region that is smaller than the main body presence region in the longitudinal direction. and a main-body-absent region located outside the diaper body and where the absorbent main body is not present, wherein, in adjacent sizes of disposable diapers among the plurality of types of disposable diapers, the longitudinal length of the crotch region that does not overlap with the ventral side portion and the dorsal side portion of the absorbent main body is longer in the disposable diaper of a larger size than in the disposable diaper of a smaller size, and the increase in the longitudinal length from the main-body-absent region of the disposable diaper of a smaller size to the main-body-absent region of the disposable diaper of a larger size is set so that the increase rate, as expressed by the following formula, is in the range of 4.1 to 39.4%: Increase rate (%) = (the increase amount) / (the longitudinal length of the disposable diaper of a larger size in an unfolded state) x 100, a disposable diaper product group.

[0011] In this disposable diaper product group, the longitudinal length of the crotch region, which does not overlap the ventral and dorsal portions of the absorbent main body, is longer in larger disposable diapers than in smaller disposable diapers. Therefore, the diameter of the leg openings increases with increasing size. This reduces the likelihood of the inner thighs getting caught in the leg openings. Furthermore, the rate of increase in longitudinal length from the non-main body region of the smaller disposable diaper to the non-main body region of the larger disposable diaper is set to fall within a predetermined range. Therefore, the length of the non-main body region increases sufficiently with increasing size. This reduces the likelihood of the abdominal region being covered by the non-main body region, regardless of size. Therefore, when a larger disposable diaper is put on a child as their body grows, the synergistic effects of the inner thighs not getting caught in the leg openings, making it easier to pull up the diaper to the appropriate position, and the non-main body region easily covering the abdomen, allow the abdomen to be covered sufficiently, even up to the navel.

[0012] [Aspect 2] A group of disposable diaper products as described in Aspect 1, wherein in each of the adjacent sizes of disposable diapers, the sum of the longitudinal length of the ventral portion and the longitudinal length of the dorsal portion is the same, the widthwise length of the ventral portion and the widthwise length of the dorsal portion are the same, and the disposable diaper of the larger size has a longer longitudinal length in the unfolded state than the disposable diaper of the smaller size.

[0013] In this disposable diaper product group, due to the above-mentioned configuration, the longitudinal length of the crotch region also increases with size. Therefore, without significantly changing the configuration of the ventral and dorsal sections, the leg circumference increases with the size of the disposable diaper, allowing for greater ease of movement. This makes it possible to provide disposable diapers of optimal size that allow for greater ease of movement even as the wearer becomes more active as their body grows, while minimizing changes in fit due to the size of the disposable diaper. This allows for more reliable coverage of the abdomen, even above the navel.

[0014] [Aspect 3] A disposable diaper product group according to Aspect 1 or 2, wherein each of the ventral portion and the dorsal portion has a plurality of waist elastic members extending along the width direction and spaced apart in the longitudinal direction, and in each of the disposable diapers of adjacent sizes, the sum of the longitudinal length of the ventral portion and the longitudinal length of the dorsal portion is the same, the widthwise length of the ventral portion and the widthwise length of the dorsal portion are the same, and the stretch ratio of the plurality of waist elastic members is lower in the larger-sized disposable diaper than in the smaller-sized disposable diaper.

[0015] As described above, in this disposable diaper product line, the elastic stretch ratio of the waist elastic members of the disposable diapers is reduced as the size increases, without significantly changing the configuration of the ventral and dorsal sections. This reduces the tightening force of the waist elastic members as the size increases, allowing for easier movement. This makes it possible to provide disposable diapers of optimal sizes that minimize changes in fit due to the size of the disposable diaper and allow for easier movement even as the wearer becomes more active as their body grows. This allows for more reliable coverage of the abdomen, and even above the navel.

[0016] [Aspect 4] A disposable diaper product group according to any one of Aspects 1 to 3, wherein each of the ventral portion and the dorsal portion has a plurality of waist elastic members extending along the width direction and spaced apart in the longitudinal direction, wherein in each of the disposable diapers of adjacent sizes, the sum of the longitudinal length of the ventral portion and the longitudinal length of the dorsal portion is the same, the widthwise length of the ventral portion and the widthwise length of the dorsal portion are the same, and the larger-sized disposable diaper has a smaller number of the waist elastic members than the smaller-sized disposable diaper.

[0017] As described above, in this disposable diaper product line, the number of waist elastic members in the disposable diaper is reduced as the size increases, without significantly changing the configuration of the ventral and dorsal sections. This reduces the tightening force of the waist elastic members as the size increases, allowing for easier movement. This makes it possible to provide disposable diapers of optimal sizes that minimize changes in fit due to the size of the disposable diaper and allow for easier movement even as the wearer becomes more active as their body grows. This allows for more reliable coverage of the abdomen, and even above the navel.

[0018] [Aspect 5] A group of disposable diaper products described in any one of aspects 1 to 4, wherein the longitudinal length of the main body non-existent region of the abdominal side portion in each of the plurality of types of disposable diapers is 21 mm or more.

[0019] In this disposable diaper product group, the longitudinal length of the non-main-body region of the ventral side of each of the multiple types of disposable diapers is 21 mm or more regardless of size. This makes it easier to grasp the non-main-body region of the ventral side. As a result, when putting the disposable diaper on a baby, the non-main-body region of the ventral side can be grasped and easily spread forward and backward, which in turn makes it easier to widen the leg openings. This makes it less likely that the inner thighs will get caught in the leg openings, making it easier to pull the diaper up to the correct position.

[0020] [Aspect 6] A group of disposable diaper products described in any one of aspects 1 to 5, wherein the ratio of the non-main body area in the abdominal portion of the larger-sized disposable diaper to the non-main body area in the abdominal portion of the smaller-sized disposable diaper is 1.3 or more.

[0021] In this disposable diaper product group, the ratio of the non-main body area in the abdominal side of a large-sized disposable diaper to the non-main body area in the abdominal side of a small-sized disposable diaper is 1.3 or more. This allows the abdominal side to be more reliably covered, i.e., up to the navel, even when the disposable diaper is changed from a small size to a large size as the child grows.

[0022] [Aspect 7] A group of disposable diaper products described in any one of aspects 1 to 6, wherein the absorbent main body includes an absorbent body having an absorbent core, and each of the ventral side portion and the dorsal side portion has, in the longitudinal direction, an absorbent body presence region in which the absorbent core is present, and an absorbent body non-presence region located outside the absorbent body presence region in which the absorbent core is not present, and the ratio of the longitudinal length of the absorbent body non-presence region to the longitudinal length of each of the multiple types of disposable diapers in an unfolded state is 29% or more.

[0023] In this disposable diaper product group, the ratio of the absorbent-free region to the longitudinal length of the disposable diaper in its unfolded state is 29% or more. This makes it easier to grasp the absorbent-free region. As a result, when putting the disposable diaper on a baby, the absorbent-free region can be grasped and easily spread forward and backward, which in turn makes it easier to widen the leg openings. This makes it less likely that the inner thighs will get caught in the leg openings, making it easier to pull the diaper up to the correct position.

[0024] [Aspect 8] A disposable diaper product group described in any one of aspects 1 to 7, further comprising a sheet-like stretchable member located in the non-main body area in at least one of the ventral side portion and the back side portion and extending along the width direction.

[0025] In this disposable diaper product group, a sheet-like stretchable member extending in the width direction is disposed in the non-main-body region of at least one of the ventral and dorsal sections. This allows the entire waist section, comprised of the ventral and dorsal sections, to tighten the body over a wide area. This improves the fit of the disposable diaper and also makes it less likely for the waist section to slip down after the ventral section has fully covered the abdomen, i.e., up to the navel.

[0026] [Aspect 9] A group of disposable diaper products described in any one of Aspects 1 to 8, wherein in each of the plurality of types of disposable diapers, when the regions obtained by dividing each of the ventral portion and the dorsal portion in the longitudinal direction into four sections are designated as first to fourth sections in order from the outside in the longitudinal direction, the widthwise tensile stress in the fourth section in each of the ventral portion and the dorsal portion is smaller than the widthwise tensile stress in each of the first to third sections in each of the ventral portion and the dorsal portion.

[0027] In this disposable diaper product group, when each of the ventral and dorsal sections is longitudinally divided into four sections, the widthwise tensile stress of the fourth section, which is the innermost section in the longitudinal direction (the lower side / leg opening side), is smaller than the widthwise tensile stress of the remaining sections, from the first section to the third section. Therefore, when putting the disposable diaper on a child, the lowermost sections (leg openings) in the longitudinal direction through which the legs pass can be easily expanded. This makes it less likely for the leg openings to get caught on the child's inner thighs, making it easier to pull up the disposable diaper. This allows the abdomen to be fully covered, i.e., up to the navel.

[0028] [Aspect 10] A disposable diaper product group described in any one of Aspects 1 to 9, wherein each of the ventral portion and the dorsal portion has a plurality of waist elastic members extending along the width direction and spaced apart in the longitudinal direction, and in each of the plurality of types of disposable diapers, when the regions obtained by dividing each of the ventral portion and the dorsal portion in the longitudinal direction into four regions are designated as first to fourth regions in order from the outside in the longitudinal direction, the number of waist elastic members per unit length in the longitudinal direction in the dorsal portion is smaller in the fourth region than in the third region.

[0029] In this disposable diaper product group, when the back section is divided into four longitudinal sections, the number of waist-circumference elastic members per unit longitudinal length is smaller in the fourth section, which is the innermost longitudinal section (lower side / leg opening side), than in the third section, which is located above it. This allows the lowermost longitudinal sections (leg openings) of the ventral and back sections, through which the legs pass, to expand more easily when the disposable diaper is put on a child. This prevents the leg openings from getting caught on the child's inner thighs, making it easier to pull up the disposable diaper. This allows the abdomen to be fully covered, i.e., up to the navel.

[0030] [Aspect 11] A disposable diaper product group according to any one of Aspects 1 to 10, wherein each of the ventral portion and the dorsal portion has a plurality of waist elastic members extending along the width direction and spaced apart in the longitudinal direction, and in each of the plurality of types of disposable diapers, when the ventral portion and the dorsal portion are divided into four regions in the longitudinal direction, designated as first to fourth regions in order from the outside in the longitudinal direction, the waist elastic members of the ventral portion and the dorsal portion are not aligned in the longitudinal direction in the fourth region.

[0031] In this disposable diaper product group, when each of the ventral and dorsal sections is longitudinally divided into four, the longitudinal positions of the waist elastic members of the ventral section and the dorsal section do not coincide in the fourth region, which is the innermost longitudinal region (lower side / leg opening side). This reduces the strong tightening force that would otherwise be generated when the longitudinal positions of the waist elastic members of the ventral section and the dorsal section coincide in the fourth region. This reduces the tightening force at the lowermost longitudinal portion (leg opening portion) of the ventral and dorsal sections through which the legs pass. This reduces the likelihood of the leg openings getting caught on the child's inner thighs, making it easier to pull up the disposable diaper. This ensures adequate coverage of the abdomen, i.e., coverage up to the navel.

[0032] [Aspect 12] A disposable diaper product group described in any one of Aspects 1 to 11, wherein the absorbent main body includes an absorbent main body central portion located in the center of the width direction and having an absorbent body, and a pair of leg gather portions located at both ends of the width direction and having a plurality of leg elastic members extending along the longitudinal direction, and when each of the pair of leg gather portions is divided in half in the width direction into an outer outer region and an inner inner region, those of the plurality of leg elastic members located in the outer region have a lower tensile stress than those located in the inner region.

[0033] In this disposable diaper product group, the leg gathers have a lower tensile stress in the outer regions of the leg elastic members than in the inner regions. Because the outer regions of the leg gathers, which are closer to the legs, have a lower tensile stress, the lower end (leg openings) through which the legs pass can be more easily expanded when putting the disposable diaper on a child. This makes it less likely for the leg openings to get caught on the child's inner thighs, making it easier to pull up the disposable diaper. This allows the abdomen to be fully covered, i.e., up to the navel.

[0034] [Aspect 13] In adjacent sizes of disposable diapers among the plurality of types of disposable diapers, the increase in longitudinal length from the non-main body region of the smaller size disposable diaper to the non-main body region of the larger size disposable diaper is further set so that a second increase rate, as expressed by the following formula, is in the range of 5.4 to 68.4%, second increase rate (%) = (amount of increase) / (longitudinal length of the absorbent main body in the larger size disposable diaper) x 100, a disposable diaper product group described in any one of aspects 1 to 12.

[0035] In this disposable diaper product group, the second increase rate of the longitudinal length from the non-main body region of a smaller size disposable diaper to the non-main body region of a larger size disposable diaper is set to be within a predetermined range. Therefore, as the size increases, the length of the non-main body region also increases sufficiently. This makes it possible to more reliably ensure that the non-main body region can easily cover the abdominal area regardless of size.

[0036] [Aspect 14] In adjacent sizes of disposable diapers among the plurality of types of disposable diapers, the increase in the longitudinal length from the non-main body region of the smaller size disposable diaper to the non-main body region of the larger size disposable diaper is set so that the third increase rate, as expressed by the following formula, is in the range of 4.4 to 65.0%, third increase rate (%) = (the increase amount) / (the longitudinal length of the smaller size disposable diaper in its unfolded state) x 100, a disposable diaper product group described in any one of aspects 1 to 13.

[0037] In this disposable diaper product group, the third increase rate of the longitudinal length from the non-main body region of a smaller size disposable diaper to the non-main body region of a larger size disposable diaper is set to be within a predetermined range. Therefore, as the size increases, the length of the non-main body region also increases sufficiently. This makes it possible to more reliably ensure that the non-main body region can easily cover the abdominal area regardless of size.

[0038] [Aspect 15] In adjacent sizes of disposable diapers among the plurality of types of disposable diapers, the increase in longitudinal length from the non-main body region of the smaller size disposable diaper to the non-main body region of the larger size disposable diaper is set so that a fourth increase rate, as expressed by the following formula, is in the range of 5.5 to 68.4%, Fourth increase rate (%) = (amount of increase) / (longitudinal length of the absorbent main body in the smaller size disposable diaper) x 100, a disposable diaper product group described in any one of aspects 1 to 14.

[0039] In this disposable diaper product group, the fourth increase rate of the longitudinal length from the non-main body region of a smaller size disposable diaper to the non-main body region of a larger size disposable diaper is set to be within a predetermined range. Therefore, as the size increases, the length of the non-main body region also increases sufficiently. This makes it possible to more reliably ensure that the non-main body region can easily cover the abdominal area regardless of size.

[0040] [Aspect 16] A method for manufacturing a group of disposable diaper products consisting of a plurality of types of disposable diapers of different sizes, wherein the disposable diapers have, in an unfolded state, longitudinal, width, and thickness directions which are perpendicular to one another, and comprise a ventral side portion covering the ventral side of a wearer, a dorsal side portion covering the dorsal side, and an absorbent main body covering the crotch area of ​​the wearer and including an absorbent body, The absorbent main body is formed by positioning the front and rear end portions in the longitudinal direction at the center portions in the width direction of the abdominal side portion and the back side portion, respectively, and joining both side edges in the width direction of the abdominal side portion and both side edges in the width direction of the back side portion at a pair of side joining portions, and each of the abdominal side portion and the back side portion has, in the longitudinal direction, a main body presence region in which the absorbent main body is present, and a main body absence region located outside the main body presence region and in which the absorbent main body is not present, and the longitudinal length of the crotch region of the absorbent main body that does not overlap with the abdominal side portion and the back side portion is longer in the disposable diaper of the larger size than in the disposable diaper of the smaller size, and an increase in the longitudinal length from the non-main-body region of the disposable diaper of the smallest size to the non-main-body region of the disposable diaper of the largeest size is set so that the increase rate, as expressed by the following formula, is in the range of 4.1 to 39.4%, where increase rate (%) = (the increase amount) / (the longitudinal length of the disposable diaper of the largeest size in its unfolded state) x 100; and the manufacturing method comprises: a first step of manufacturing one of the disposable diapers of the smallest size and the largeest size using predetermined equipment; a second step of changing, in the predetermined equipment, the settings of the positions at which the ventral side portion and the dorsal side portion are connected to the absorbent main body; and a third step of manufacturing the other of the disposable diapers of the smallest size and the largeest size using the predetermined equipment.

[0041] This manufacturing method for the disposable diaper product line allows adjacent sizes of disposable diapers to be manufactured using a single predetermined facility. This allows for efficient manufacturing of a disposable diaper product line consisting of multiple types of disposable diapers of different sizes. Furthermore, as described above, when a disposable diaper of a larger size is put on a child as the child grows, the diaper is easily pulled up to the correct position because the inner thighs are less likely to get caught in the leg openings. Furthermore, the non-main-body region makes it easy to cover the abdomen. This synergistic effect allows the diaper to adequately cover the abdomen, even up to the navel.

[0042] Hereinafter, a disposable diaper according to an embodiment of the present invention will be described using a so-called three-piece type disposable diaper as an example. However, the present invention is not limited to this embodiment and example, and can be applied to various disposable diapers for children and adults without departing from the subject matter of the present invention, such as a so-called two-piece type disposable diaper.

[0043] 1 to 4 are diagrams showing a disposable diaper 1 according to this embodiment. FIG. 1 is a perspective view showing an example of the configuration of the disposable diaper 1. FIG. 2 is a plan view showing the example of the configuration of the disposable diaper 1 in an unfolded state, and therefore shows the state in which the elastic members and stretchable members are stretched. FIG. 3 is a cross-sectional view taken along the longitudinal center line CL in FIG. 2. FIG. 4 is a cross-sectional view taken along the widthwise center line CW in FIG. 2.

[0044] In the unfolded state shown in Figures 2 to 4, the disposable diaper 1 has a longitudinal direction L, a width direction W, and a thickness direction T that are perpendicular to one another. The disposable diaper 1 has a longitudinal centerline CL that passes through the center of the width direction W and extends along the longitudinal direction L, and a widthwise centerline CW that passes through the center of the longitudinal direction L and extends along the width direction W. Here, the directions and sides approaching the longitudinal centerline CL are referred to as the inward and inner sides of the width direction W, respectively, and the directions and sides moving away from the longitudinal centerline CL are referred to as the outward and outer sides of the width direction W, respectively. Meanwhile, the directions and sides approaching the widthwise centerline CW are referred to as the inward and inner sides of the longitudinal direction L, respectively, and the directions and sides moving away from the widthwise centerline CW are referred to as the outward and outer sides of the longitudinal direction L, respectively. Furthermore, the term "planar view" refers to the state in which the disposable diaper 1 is placed on a plane and viewed in the thickness direction T from a position perpendicular to the plane, and the shape as seen in the planar view is referred to as the "planar shape," and any direction within a plane including the longitudinal direction L and the width direction W is referred to as the "planar direction." The terms "skin side" and "non-skin side" refer to the side relatively closer to and farther from the wearer's skin surface in the thickness direction T of the disposable diaper 1 when the disposable diaper 1 is worn. In the longitudinal direction L, the side relatively closer to the ventral portion (described below) or the side relatively farther from the dorsal portion (described below) is also referred to as the ventral side or the front side, and the side relatively closer to the dorsal portion or the side relatively farther from the ventral portion is also referred to as the dorsal side or the rear side. The above definitions are also used for each material of the disposable diaper 1 and for the disposable diaper 1 in the state shown in FIG. 1 .

[0045] Note that a component, structure, shape, etc. aligned with the longitudinal direction L includes not only a component parallel to the longitudinal direction L but also a component within a range of ±30° relative to the longitudinal direction L. Similarly, a component aligned with the width direction W includes not only a component parallel to the width direction W but also a component within a range of ±30° relative to the width direction W. For components with curved or curved surfaces, the component is evaluated as described above for the tangents at each point on the curve.

[0046] The disposable diaper 1 comprises a ventral section 3, a dorsal section 2, and an absorbent main body 4 located between the ventral section 3 and the dorsal section 2. The ventral section 3 is a section of the disposable diaper 1 that covers the ventral side of the wearer. The absorbent main body 4 is a section of the disposable diaper 1 that covers the crotch area of ​​the wearer and includes an absorber 8. The dorsal section 2 is a section of the disposable diaper 1 that covers the dorsal side of the wearer. The front and rear ends of the absorbent main body 4 in the longitudinal direction L are connected to the central portions of the ventral section 3 and the dorsal section 2 in the width direction W, respectively, by, for example, an adhesive (e.g., a hot melt adhesive; the same applies hereinafter). The disposable diaper 1 is formed by joining a pair of ventral joining portions 3a located at both end edges of the ventral section 3 in the width direction W and a pair of dorsal joining portions 2a located at both end edges of the dorsal section 2 in the width direction W to each other. The pair of ventral-side joints 3a and the pair of dorsal-side joints 2a joined together are also referred to as a pair of side joints SC. In this case, in the disposable diaper 1, the ventral-side section 3 and the dorsal-side section 2 joined together at the pair of side joints SC form a waist section WP that covers the wearer's waist. Furthermore, the outer ends of the ventral-side section 3 and the dorsal-side section 2 in the longitudinal direction L define a waist opening WH through which the wearer's waist passes. Furthermore, in the disposable diaper 1, the opposite ends of the absorbent main body 4 in the width direction W and the inner ends of the ventral-side section 3 and the dorsal-side section 2 in the longitudinal direction L define a pair of leg openings LH through which the wearer's pair of legs pass.

[0047] In the unfolded state, the abdominal section 3 and the back section 2 each have a generally rectangular shape that is elongated in the width direction W and are spaced apart from each other in the longitudinal direction L. The absorbent main body 4 has a generally rectangular shape that is elongated in the longitudinal direction L, and one end in the longitudinal direction L is connected to the abdominal section 3 and the other end to the back section 2. The abdominal section 3, the absorbent main body 4, and the back section 2 are formed separately from each other. At least two of the abdominal section 3, the absorbent main body 4, and the back section 2 may be formed integrally or may be connected integrally by a separate outer sheet or the like. For example, if the abdominal section 3 and the back section 2 share at least one of the sheet members that constitute the abdominal section 3 and the back section 2 and are formed integrally from a continuous sheet member, the disposable diaper 1 can be said to be a two-piece type. A three-piece disposable diaper is a disposable diaper which, in an unfolded state, has a ventral portion 3, a dorsal portion 2, and a crotch portion between the ventral portion 3 and the dorsal portion 2, with the crotch portion joining the ventral portion 3 and the dorsal portion 2 and separating the ventral portion 3 and the dorsal portion 2. A two-piece disposable diaper is a disposable diaper which, in an unfolded state, has a ventral portion 3, a dorsal portion 2, and a crotch portion between the ventral portion 3 and the dorsal portion 2, with the crotch portion being joined to the ventral portion and the dorsal portion by a single outer body.

[0048] The ventral portion 3 and the back portion 2 are each formed from a liquid-impermeable sheet material. Each of the ventral portion 3 and the back portion 2 is formed by stacking at least a sheet material located on the skin side and a sheet material located on the non-skin side in the thickness direction T and joining them with an adhesive, heat sealing, or the like (the same applies below). The outer end of the sheet material located on the non-skin side in the longitudinal direction L is folded back toward the skin side. In this case, the non-skin side sheet material at the folded position in each of the ventral portion 3 and the back portion 2 constitutes the end of the ventral portion 3 and the back portion 2 in the longitudinal direction L, respectively.

[0049] The abdominal portion 3 includes a plurality of waist-gathering elastic members 13 between the sheet member located on the skin side and the sheet member located on the non-skin side. The plurality of waist-gathering elastic members 13 extend from one end to the other end of the abdominal portion 3 in the width direction W, except for a region overlapping with the center of the absorbent body 8 in the thickness direction T, along the width direction W, and are arranged at intervals in the longitudinal direction L. The skin- and non-skin-side sheet members and the plurality of waist-gathering elastic members 13 are joined with an adhesive or the like. The back portion 2 includes a plurality of waist-gathering elastic members 12a, 12b between the sheet member located on the skin side and the sheet member located on the non-skin side. The plurality of waist-gathering elastic members 12a extend from one end to the other end of the back portion 2 in the width direction W, except for a region overlapping with the center of the absorbent body 8 in the thickness direction T, and are arranged at intervals in the longitudinal direction L. The multiple waist elastic members 12b extend along the width direction W of the back portion 2 from one end to the other end in the width direction W, and are spaced apart in the longitudinal direction L. The skin-side and non-skin-side sheet members and the multiple waist elastic members 12a, 12b are bonded with an adhesive or the like. The multiple waist elastic members 12a, 12b, 13 stretch the waist portion WP. The material of each elastic member is not particularly limited, but examples include thread-like or sheet-like rubber. The type of each elastic member is not particularly limited, but examples include styrene butadiene rubber and urethane rubber. The characteristics of each elastic member, such as the cross-sectional size (wire diameter, etc.) and elongation ratio, are appropriately selected depending on the magnitude of the tightening force corresponding to the position within the waist portion WP.

[0050] Examples of each sheet member include any liquid-impermeable sheet, such as a liquid-impermeable nonwoven fabric or synthetic resin film, a composite sheet of these, an SB nonwoven fabric, or an SMS nonwoven fabric. The type of nonwoven fabric is not particularly limited, and examples include meltblown nonwoven fabric, spunbond nonwoven fabric, airlaid nonwoven fabric, and air-through nonwoven fabric. The material of the nonwoven fabric or synthetic resin film of the sheet member is not particularly limited as long as it can be used for sanitary products, and examples include polyolefin resins such as polypropylene and polyethylene, polyamide resins such as 6-nylon and 6,6-nylon, and polyester resins such as polyethylene terephthalate and polybutylene terephthalate. The basis weight of the nonwoven fabric of the sheet member is, for example, 5 to 100 g / m2, preferably 10 to 50 g / m2. The length (thickness) of the sheet member in the thickness direction T is, for example, 0.1 to 5 mm, preferably 0.1 to 2 mm. The sheet members constituting each of the ventral side portion 3 and the dorsal side portion 2 may be one or three or more sheets (not shown). The sheet members do not have to be folded (not shown).

[0051] In this embodiment, the disposable diaper 1 further includes an exterior sheet member 14 that bridges the gap between the ventral portion 3 and the dorsal portion 2. The exterior sheet member 14 is a liquid-impermeable sheet member, such as a nonwoven fabric, and both ends in the longitudinal direction L are laminated to the ventral portion 3 and the dorsal portion 2, respectively, and bonded thereto with an adhesive or the like. The type and material of the nonwoven fabric are as described above. The exterior sheet member 14 is also bonded with an adhesive or the like to the non-skin side of the absorbent main body 4, which is disposed generally between the ventral portion 3 and the dorsal portion 2, to support and protect the absorbent main body 4 from the non-skin side. The exterior sheet member 14 may be composed of two or more sheet members (not shown). A sheet member other than the exterior sheet member 14 may be provided on the non-skin side (not shown).

[0052] The disposable diaper 1 may further include a sheet-like elastic member 50 bonded with an adhesive to the skin side, non-skin side, or interior of at least one of the abdominal portion 3 and the back portion 2, and extending along the width direction W. In this embodiment, the sheet-like elastic member 50 is disposed inside the abdominal portion 3, generally in the region of the outer edge of the abdominal portion 3 in the longitudinal direction L and throughout the width direction W. The sheet-like elastic member 50 is a sheet-like member that is elastic in the width direction W, and functions, for example, as a waist gather and / or a sweat-absorbing sheet. Examples of types of sheet-like elastic member 50 include elastic nonwoven fabrics that are composites of styrene rubber, olefin rubber, urethane rubber, or the like with nonwoven fabric, paper, or the like.

[0053] The absorbent main body 4 includes a main body central portion 10 located at the center in the width direction W and extending along the longitudinal direction L, and a pair of leg gather portions 5 located at both ends in the width direction W and extending along the longitudinal direction L. Each of the pair of leg gather portions 5 extends along the longitudinal direction L and has a plurality of leg elastic members 5a arranged at intervals in the width direction W.

[0054] The main body central portion 10 has a substantially rectangular shape and includes a liquid-permeable topsheet 7, a liquid-impermeable backsheet 9, and an absorbent body 8 that is positioned between the topsheet 7 and the backsheet 9 and absorbs and retains liquid. The absorbent body 8 is bonded to the topsheet 7 and the backsheet 9 with an adhesive, and the topsheet 7 and the backsheet 9 are bonded to each other with an adhesive at their peripheral edges. The shape of the main body central portion 10 is not limited to the above example as long as it is long in the longitudinal direction L, and examples include a rectangle with rounded corners, a rectangle with outwardly convex curved short sides, and an hourglass shape.

[0055] Examples of the top sheet 7 include liquid-permeable nonwoven fabrics or woven fabrics, synthetic resin films with liquid-permeable holes, and composite sheets of these. Examples of the back sheet 9 include liquid-impermeable nonwoven fabrics or synthetic resin films, composite sheets of these, and SMS nonwoven fabrics. The type of nonwoven fabric is not particularly limited, and examples include meltblown nonwoven fabrics, spunbond nonwoven fabrics, airlaid nonwoven fabrics, and air-through nonwoven fabrics. The type of synthetic resin film is not particularly limited, and known film materials can be used. Materials for the nonwoven fabric and synthetic resin film are not particularly limited as long as they are usable for sanitary products, and examples include olefin-based resins such as polyethylene and polypropylene, polyamide-based resins such as 6-nylon and 6,6-nylon, and polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate. Cellulose-based fibers may also be used as the nonwoven fabric material. To impart breathability, the synthetic resin film may contain inorganic particles such as calcium carbonate.

[0056] The absorbent body 8 includes an absorbent core 8b that absorbs and retains liquid, a core wrap 8a that encases the absorbent core 8b, and grooves 8c that can diffuse liquid in the longitudinal direction L and the width direction W. The material of the absorbent core 8b can be an absorbent material, such as at least one of cellulose-based fibers and superabsorbent polymers. Examples of cellulose-based fibers include natural cellulose fibers such as pulp fibers (e.g., wood pulp fibers, crosslinked pulp fibers, and non-wood pulp fibers), regenerated cellulose fibers, and semi-synthetic cellulose fibers. Pulp fibers have an average fiber length of, for example, several tens of microns, preferably 20 to 40 microns, and an average fiber length of, for example, several millimeters, preferably 2 to 5 mm. Examples of superabsorbent polymers (SAPs) include polyacrylate-based, polysulfonate-based, and maleic anhydride-based superabsorbent polymers. The size (when dry) of the superabsorbent polymer is, for example, an average particle size of several hundred μm, preferably 200 to 500 μm. The basis weight of the cellulose fiber and the superabsorbent polymer is, for example, 100 to 400 g / m, respectively. ２Examples of materials for the core wrap 8a include liquid-permeable sheets such as nonwoven fabrics and tissues.

[0057] The absorbent body 8 may have a two-layer structure (not shown) with an upper layer facing the skin and a lower layer facing away from the skin, or a multi-layer structure with three or more layers. The grooves 8c may be located in only one of the upper and lower layers, or may penetrate both the upper and lower layers in the thickness direction T. Alternatively, the grooves 8c may be located in both the upper and lower layers, with the grooves 8c alternately positioned (not continuously penetrating the two layers). The presence of the grooves 8c allows the absorbent body 8 to shrink in the width direction W when the wearer closes their legs, improving the fit after wearing and helping to reduce leakage. Furthermore, the length of the absorbent body 8 in the width direction W shrinks (becomes thinner) to fit the body, making it easier to pull the disposable diaper 1 up to the abdomen (navel).

[0058] The main body central portion 10 includes a pair of leak-proof walls 6 arranged on both sides in the width direction W facing each other and extending along the longitudinal direction L. Each leak-proof wall 6 extends along the longitudinal direction L and is formed of a sheet member 6b containing multiple leak-proof elastic members 6a arranged at intervals in the width direction W. Each leak-proof wall 6 has an outer end in the width direction W bonded to at least one of the topsheet 7, absorbent body 8, and backsheet 9 with an adhesive or the like to form a fixed end, and an inner end in the width direction W spaced apart from the other sheets, including the topsheet 7, to form a free end. The multiple leak-proof elastic members 6a are bonded to the sheet member 6b near the free end with an adhesive. Examples of the sheet member 6b include hydrophobic nonwoven fabrics and hydrophilic nonwoven fabrics. The type and material of the nonwoven fabric are as described above. The multiple leak-proof elastic members 6a are exemplified by rubber threads, and the type and material of the elastic members are as described above. The properties of the elastic member, such as the cross-sectional size (wire diameter, etc.) and the elongation ratio, are appropriately selected depending on the function of the leak preventing walls 6. Note that the inner end of each leak preventing wall 6 in the width direction W may be further folded back outward in the width direction W.

[0059] A pair of leg gathers 5 are joined to both ends of the main body central portion 10 in the width direction W. Each leg gather 5 extends along the longitudinal direction L and includes multiple leg elastic members 5a spaced apart in the width direction W, and skin-side and non-skin-side sheet members 5b sandwiching the multiple leg elastic members 5a. Each leg gather 5 has its inner end in the width direction W joined to the non-skin-side surface of the width direction W end of the main body central portion 10 with an adhesive or the like to form a fixed end, and its outer end in the width direction W separated from the main body central portion 10 to form a free end. The multiple leg elastic members 5a are joined with an adhesive near the free ends of the skin-side and non-skin-side sheet members 5b. The multiple leg elastic members 5a stretch each leg gather 5. Examples of sheet members 5b include hydrophobic nonwoven fabrics and hydrophilic nonwoven fabrics. The type and material of the nonwoven fabric are as described above. The leg elastic members 5a are exemplified by rubber threads, and the types and materials of the elastic members are as described above. The properties of the elastic members, such as the cross-sectional size (linearity, etc.) and elongation ratio of the elastic members, are appropriately selected depending on the magnitude of the tightening force corresponding to the position in the leg gathered portion 5.

[0060] In the disposable diaper 1, the pair of leg gathers 5 are bridged by an exterior sheet member 14. Both ends of the exterior sheet member 14 in the width direction W are laminated to the inner ends of each of the pair of leg gathers 5 in the width direction W and joined with an adhesive or the like, thereby supporting and protecting the pair of leg gathers 5 from the non-skin side.

[0061] The back portion 2 includes a back main body portion 21 that occupies substantially the same area in the longitudinal direction L as the back joint portion 2a, and a back extension portion 20 that extends forward from the front edge of the back main body portion 21 in the longitudinal direction L. In other words, the back main body portion 21 is the rear region of the back portion 2 in the longitudinal direction L, and its length in the longitudinal direction L is substantially the same as that of the back joint portion 2a and its length in the width direction W is the same as that of the back portion 2. The waist elastic members 12a, 12b of the back portion 2 are arranged in the back main body portion 21. Therefore, the back main body portion 21 is the region where at least the waist elastic members 12a, 12b are arranged. The meaning of "substantially the same area as the back joint portion 2a" will be explained later. On the other hand, the back-side extension portion 20 is a region on the front side (inner side) of the back portion 2 in the longitudinal direction L, and its length in the longitudinal direction L is the length of the back portion 2 minus the length of the back main body portion 21, and its length in the width direction W is the same as that of the back portion 2. The back-side extension portion 20 is the remaining region of the back portion 2 minus the back main body portion 21.

[0062] The back-side extending portion 20 includes an extending central portion 31 that overlaps the main body central portion 10 in the thickness direction T, and a pair of buttocks covering portions 30 that extend outward from both side edges of the extending central portion 31 in the width direction W. In other words, the extending central portion 31 is a central (inner) region of the back-side extending portion 20 in the width direction W, and its length in the width direction W is the same as the length of the main body central portion 10 and its length in the longitudinal direction L is the same as the length of the back-side extending portion 20. On the other hand, the buttocks covering portion 30 is a region of the back-side extending portion 20 outside in the width direction W, and its length in the width direction W is half the length of the back-side extending portion 20 minus the length of the main body central portion 10, and its length in the longitudinal direction L is the same as the length of the back-side extending portion 20. The buttocks covering portion 30 can also be said to be a region of the back-side extending portion 20 that does not overlap with the main body central portion 10 in the thickness direction T.

[0063] FIG. 5 is a partial plan view showing an example of the configuration of the disposable diaper 1 according to this embodiment in an unfolded state. This figure is an enlarged view of the area surrounding the buttocks-covering portion 30, and can also be considered a view showing the extended state. As described above, the length of the buttocks-covering portion 30 in the width direction W, i.e., the extended widthwise length dWa, is calculated by subtracting the length of the main body central portion 10 (or the extended central portion 31) from the length of the back-side extending portion 20, and then dividing the result by half. Meanwhile, the length in the longitudinal direction L, i.e., the extended longitudinal length dLa, is the same as the length of the back-side extending portion 20. The buttocks-covering portion 30 includes a buttocks elastic member 40 extending along the width direction W in an inner region of the longitudinal direction L. The effective portion of the buttocks elastic member 40 as an elastic member is within the width direction W of the buttocks-covering portion 30. The buttocks elastic member 40 is exemplified by rubber thread, and the type and material of the elastic member are as described above. The properties of the elastic member, for example, the cross-sectional size (linearity, etc.) and the elongation ratio of the elastic member, are appropriately selected according to the magnitude of the fastening force corresponding to the position inside the buttocks covering portion 30.

[0064] Here, when we say that "the dorsal main body portion 21 occupies substantially the same area as the dorsal joint portion 2a in the longitudinal direction L," the meaning of "substantially the same area as the dorsal joint portion 2a" is as follows. As shown in FIG. 5 , the end P on the inner side (front side) of the dorsal joint portion 2a in the longitudinal direction L is included in the dorsal extension portion 20, not the dorsal main body portion 21. However, the length of the end P in the longitudinal direction L is small compared to the entire length of the dorsal joint portion 2a. Therefore, the area that the dorsal main body portion 21 occupies in the dorsal portion 2 in the longitudinal direction L is the range obtained by excluding the length of the end P from the range of the dorsal joint portion 2a, but is still "substantially" the same area as the dorsal joint portion 2a. The ratio of the length of the end P to the length of the dorsal joint portion 2a in the longitudinal direction L is, for example, 2 to 4%, and the actual length is, for example, 2 to 5 mm.

[0065] The buttocks-covering portion 30 includes a plurality of rigid portions 2h arranged continuously or intermittently along the longitudinal direction L at the outer end in the width direction W. The rigid portions 2h are arranged side by side in the longitudinal direction L on the inside (front side) of the end P of the back-side joint portion 2a. The rigid portions 2h join the sheet member located on the skin side of the back-side portion 2 and the sheet member located on the non-skin side in the thickness direction T. The rigid portions 2h are exemplified by, for example, heat sealing.

[0066] The following describes the relationship between adjacent sizes of disposable diapers 1 in a product group of disposable diapers 1 consisting of multiple types of disposable diapers 1 of different sizes. Examples of the relationship between adjacent sizes of disposable diapers 1 include the relationship regarding the lengths of the components of the disposable diapers 1. Examples of adjacent sizes include medium size and large size.

[0067] 6 is a plan view of an example of the configuration of a disposable diaper 1 according to an embodiment in an unfolded state. In this figure, the length of the disposable diaper 1 in the longitudinal direction L is defined as LLO, the length of the back portion 2 in the longitudinal direction L is defined as LLA, the length of the back portion 2 in the width direction W is defined as WWA, the length of the abdominal portion 3 in the longitudinal direction L is defined as LLB, the length of the abdominal portion 3 in the width direction W is defined as WWB, and the length LLC in the longitudinal direction L of the crotch region 4a of the absorbent main body 4 that does not overlap with the abdominal portion 3 and the back portion 2. The length LLC can also be considered as the distance between the abdominal portion 3 and the back portion 2.

[0068] The back section 2 has a main body presence region AX2 and a main body non-presence region AX1 in the longitudinal direction L. The main body presence region AX2 is a region in the longitudinal direction L where the absorbent main body 4 is present in the back section 2. The main body presence region AX2 can also be said to be a region that overlaps with the absorbent main body 4 in the thickness direction T in the longitudinal direction L. The length LAx2 of the main body presence region AX2 in the longitudinal direction L is the length in the longitudinal direction L of the region where the absorbent main body 4 and the back section 2 overlap in the thickness direction T in the longitudinal direction L. The length in the width direction W of the main body presence region AX2 is the same as the length WWA of the width direction W of the back section 2. On the other hand, the main body non-presence region AX1 is located outside the main body presence region AX2 in the longitudinal direction L and is a region where the absorbent main body 4 is not present. The main body absent region AX1 can also be said to be a region that does not overlap in the longitudinal direction L with the absorbent main body 4 in the back section 2 in the thickness direction T. In the main body absent region AX1, the length LAx1 in the longitudinal direction L is the length in the longitudinal direction L of the region where the absorbent main body 4 and the back section 2 do not overlap in the thickness direction T, and is the length obtained by subtracting the length LAx2 in the longitudinal direction L of the main body present region AX2 from the length LLA in the longitudinal direction L of the back section 2. The length in the width direction W is the same as the length WWA in the width direction W of the back section 2.

[0069] Similarly, in the state shown in Figure 6, the abdominal portion 3 has a main body presence region BX2 and a main body non-presence region BX1. The main body presence region BX2 is a region in the abdominal portion 3 where the absorbent main body 4 is present in the longitudinal direction L. The main body presence region BX2 can also be said to be a region that overlaps with the absorbent main body 4 in the abdominal portion 3 in the thickness direction T in the longitudinal direction L. The length LBx2 of the main body presence region BX2 in the longitudinal direction L is the length in the longitudinal direction L of the region where the absorbent main body 4 and the abdominal portion 3 overlap in the thickness direction T in the longitudinal direction L. The length in the width direction W of the main body presence region BX2 is the same as the length WWB of the width direction W of the abdominal portion 3. On the other hand, the main body non-presence region BX1 is located outside the main body presence region BX2 in the longitudinal direction L, and is a region where the absorbent main body 4 is not present. The main body absent region BX1 can also be said to be a region that does not overlap in the longitudinal direction L with the absorbent main body 4 in the abdominal portion 3 in the thickness direction T. The length LBx1 of the main body absent region BX1 in the longitudinal direction L is the length in the longitudinal direction L of the region where the absorbent main body 4 and the abdominal portion 3 do not overlap in the thickness direction T. The length in the width direction W of the main body absent region BX1 is the same as the length WWB of the width direction W of the abdominal portion 3.

[0070] The length WWB of the abdominal portion 3 in the width direction W is the same as the length WWA of the back portion 2 in the width direction W, but they may be different. In disposable diapers 1 of adjacent sizes, the length WWB of the abdominal portion 3 in the width direction W and the length WWA of the back portion 2 in the width direction W are the same, but they may increase with increasing size.

[0071] In terms of the relationship between adjacent sizes of disposable diapers 1, the length LLC of the crotch region 4a of a larger size disposable diaper (e.g., L size) is greater than that of a smaller size disposable diaper (e.g., M size). In other words, the larger the size of the disposable diaper 1, the greater the length LLC of the crotch region 4a. This allows for a larger opening for the wearer's pair of leg openings LH, which are defined by both ends of the crotch region 4a in the width direction W and the inner ends of the abdominal portion 3 and the dorsal portion 2 in the longitudinal direction L.

[0072] Furthermore, in relation to adjacent sizes of disposable diapers 1, the increase in the lengths LAx1, LBx1 (sum) in the longitudinal direction L from the main body non-existence regions AX1, BX1 of the smaller size disposable diaper 1 to the main body non-existence regions AX1, BX1 of the larger size disposable diaper 1 is set so that the increase rate, as expressed by the following formula (1), is in the range of 4.1 to 39.4%: Increase rate (%) = (increase amount) / (length LLO in the longitudinal direction L of the larger size disposable diaper 1 in the unfolded state) × 100 ... (1) The increase rate is calculated by subtracting the sum (LAx1 + LBx1) of the lengths LAx1, LBx1 in the longitudinal direction L of the main body non-existence regions AX1, BX1 of the larger size disposable diaper 1 from the sum (LAx1 + LBx1) of the lengths LAx1, LBx1 in the longitudinal direction L of the main body non-existence regions AX1, BX1 of the larger size disposable diaper 1.

[0073] By setting the rate of increase of the non-main body areas AX1 and BX1 within a predetermined range, the ventral part 3 and the dorsal part 2 can cover the waist area including the abdomen of the wearer, while not covering the area above the waist area of ​​the wearer, i.e., the area that does not need to be covered.

[0074] 11 is a perspective view showing a disposable diaper according to the embodiment in a worn state. As described above, in the disposable diaper 1 product group, the length LLC in the longitudinal direction L of the crotch region 4a of the absorbent main body 4, which does not overlap the ventral portion 3 and the dorsal portion 2, is larger in larger-sized disposable diapers than in smaller-sized disposable diapers. Therefore, as the size increases, the opening diameter of the leg openings LH increases. This makes it less likely that the inner thighs will get caught in the leg openings LH, making it easier to pull them up. Furthermore, in the disposable diaper 1 product group, the increase rate (the above formula (1)) of the lengths LAx1 and LBx1 in the longitudinal direction L of the main body non-existence regions AX1 and BX1 from the smaller-sized disposable diaper 1 to the larger-sized disposable diaper 1 is set to a range of 4.1 to 39.4%. Therefore, as the size increases, the lengths LAx1, LBx1 of the non-main-body regions AX1, BX1 in the longitudinal direction L also become sufficiently large, making it easier for the non-main-body regions AX1, BX1 to cover the abdomen. When a larger size disposable diaper 1 is put on a child as the child grows, the inner thighs are less likely to get caught in the leg openings LH, making it easier to pull the diaper up to the correct position. Furthermore, the sufficiently large non-main-body regions AX1, BX1 make it easier to cover the abdomen. This synergistic effect ensures that the abdomen is adequately covered, even up to the navel. As a result, even when the disposable diaper 1 is changed from a smaller size to a larger size as the child grows, the abdomen can still be adequately covered, even up to the navel.

[0075] In a preferred aspect of this embodiment, in relation to adjacent sizes of disposable diapers 1, the increase in the lengths LAx1, LBx1 (total) in the longitudinal direction L from the main body non-existence areas AX1, BX1 of the smaller size disposable diaper 1 (e.g., M size) to the main body non-existence areas AX1, BX1 of the larger size disposable diaper 1 (e.g., L size) is set so that the second increase rate, as expressed by the following formula (2), is in the range of 5.4 to 68.4%: Second increase rate (%) = (increase amount) / (length in the longitudinal direction L of the absorbent main body 4 of the larger size disposable diaper 1) × 100 (2)

[0076] However, the length in the longitudinal direction L of the absorbent body 4 is the longitudinal length LLO of the disposable diaper 1 in its unfolded state - (the length LAx1 in the longitudinal direction L of the non-main body region AX1 of the back side portion 2 + the length LBx1 in the longitudinal direction L of the non-main body region BX1 of the ventral side portion 3).

[0077] In this way, for the disposable diaper 1 product group, the second increase rate (the above formula (2)) is set to be in the range of 5.4 to 68.4%. Therefore, as the size increases, the lengths LAx1 and LBx1 of the main body non-existence areas AX1 and BX1 also become sufficiently larger. This allows the main body non-existence areas AX1 and BX1 to more reliably cover the abdomen, extending up to the navel, regardless of the size.

[0078] In a preferred aspect of this embodiment, in relation to adjacent sizes of disposable diapers 1, the increase in the lengths LAx1, LBx1 (total) in the longitudinal direction L from the main body non-existence areas AX1, BX1 of the smaller size disposable diaper 1 (e.g., M size) to the main body non-existence areas AX1, BX1 of the larger size disposable diaper 1 (e.g., L size) is set so that the third increase rate, as expressed by the following formula (3), is in the range of 4.4 to 65.0%: Third increase rate (%) = (increase amount) / (length LLO of the smaller size disposable diaper 1 in the longitudinal direction L in the unfolded state) × 100 (3)

[0079] In this way, for the disposable diaper 1 product group, the third increase rate (the above formula (3)) is set to be in the range of 4.4 to 65.0%. Therefore, as the size increases, the lengths LAx1 and LBx1 of the main body non-existence regions AX1 and BX1 also become sufficiently larger. This allows the main body non-existence regions AX1 and BX1 to more reliably cover the abdomen, extending up to the navel, regardless of the size.

[0080] In a preferred aspect of this embodiment, in relation to adjacent sizes of disposable diapers 1, the increase in the lengths LAx1, LBx1 (total) in the longitudinal direction L from the main body non-existence areas AX1, BX1 of the smaller size disposable diaper 1 (e.g., M size) to the main body non-existence areas AX1, BX1 of the larger size disposable diaper 1 (e.g., L size) is set so that the fourth increase rate shown in the following formula (4) is in the range of 5.5 to 68.4%, where the length of the absorbent main body 4 in the longitudinal direction L is as described above. Fourth increase rate (%) = (increase amount) / (length in the longitudinal direction L of the absorbent main body 4 in the smaller size disposable diaper 1) × 100 ... (4)

[0081] In this way, for the disposable diaper 1 product group, the fourth increase rate (the above formula (4)) is set to be in the range of 5.5 to 68.4%. Therefore, as the size increases, the lengths LAx1 and LBx1 of the main body non-existence regions AX1 and BX1 also become sufficiently larger. This allows the main body non-existence regions AX1 and BX1 to more reliably cover the abdomen, extending up to the navel, regardless of the size.

[0082] In a preferred aspect of this embodiment, the sum of the length LLB of the ventral portion 3 in the longitudinal direction L and the length LLA of the dorsal portion 2 in the longitudinal direction L is the same for adjacent sizes of disposable diapers 1. The length WWB of the ventral portion 3 in the width direction W and the length WWA of the dorsal portion 2 in the width direction W are the same for all sizes of disposable diapers 1. The length LLO of a larger size disposable diaper 1 (e.g., L size) in the longitudinal direction L in the unfolded state is greater than that of a smaller size disposable diaper 1 (e.g., M size). That is, the larger the size of the disposable diaper 1, the greater the length LLO of the disposable diaper 1 in the longitudinal direction L. Accordingly, the larger the size of the disposable diaper 1, the greater the leg circumference, allowing for greater mobility without significantly changing the configuration of the ventral portion 3 and the dorsal portion 2. This minimizes changes in fit due to size of the disposable diaper 1, while providing optimally sized disposable diapers 1 that allow for greater mobility even when the wearer becomes more active as the body grows. Therefore, the abdomen can be covered more reliably, and the area up to the navel can be covered more reliably. Note that the sum of the length LLB of the abdominal portion 3 and the length LLA of the dorsal portion 2 is the same, as will be explained later in the manufacturing method (the same applies hereinafter).

[0083] In a preferred aspect of this embodiment, adjacent sizes of disposable diapers 1 have the same sum of the length LLB of the ventral portion 3 in the longitudinal direction L and the length LLA of the back portion 2 in the longitudinal direction L. The length WWB of the ventral portion 3 in the width direction W and the length WWA of the back portion 2 in the width direction W are also the same. The larger size disposable diaper 1 (e.g., L size) has a lower stretch ratio of the multiple waist-around elastic members 13, 12 than the smaller size disposable diaper 1 (e.g., M size). That is, by reducing the stretch ratio of the waist-around elastic members 13, 12 of the disposable diaper 1 as the size increases without significantly changing the configuration of the ventral portion 3 and the back portion 2, the tightening force of the waist-around elastic members 13, 12 is reduced as the size increases, allowing for easier movement. This minimizes changes in fit due to size of the disposable diaper 1, while providing optimally sized disposable diapers that allow for easy movement even when the wearer becomes more active as the body grows. Therefore, the abdomen can be covered more reliably, and the area above the navel can be covered more reliably.

[0084] In a preferred aspect of this embodiment, adjacent sizes of disposable diapers 1 have the same sum of the length LLB of the ventral portion 3 in the longitudinal direction L and the length LLA of the back portion 2 in the longitudinal direction L. The length WWB of the ventral portion 3 in the width direction W and the length WWA of the back portion 2 in the width direction W are also the same. The larger size disposable diaper 1 (e.g., L size) has fewer waist-around elastic members 13, 12 than the smaller size disposable diaper 1 (e.g., M size). In other words, by reducing the number of waist-around elastic members 13, 12 in the disposable diaper 1 as the size increases without significantly changing the configuration of the ventral portion 3 and the back portion 2, the tightening force of the waist-around elastic members 13, 12 is reduced as the size increases, allowing for easier movement. This minimizes changes in fit due to size of the disposable diaper, while providing optimally sized disposable diapers that allow for easy movement even when the wearer becomes more active as the body grows. Therefore, the abdomen can be covered more reliably, and the area above the navel can be covered more reliably.

[0085] In a preferred aspect of this embodiment, the length LBx1 in the longitudinal direction L of the non-main body region BX1 of the abdominal portion 3 in each of the multiple types of disposable diapers 1 is 21 mm or more. Thus, in the disposable diaper 1 product group, the length LBx1 in the longitudinal direction L of the non-main body region BX1 of the abdominal portion 3 is 21 mm or more regardless of size. This makes it easier to grasp the non-main body region BX1 of the abdominal portion 3. As a result, when putting the disposable diaper 1 on a baby, the non-main body region BX1 of the abdominal portion 3 can be grasped and easily spread forward and backward, thereby easily widening the leg openings. Therefore, the inner thighs are less likely to get caught in the leg openings, making it easier to pull the diaper up to the appropriate position.

[0086] In a preferred aspect of this embodiment, the ratio of the non-main body region BX1 of the abdominal portion 3 of the large-sized disposable diaper 1 to the non-main body region BX1 of the abdominal portion 3 of the small-sized disposable diaper 1 is 1.3 or more. Since the ratio of the non-main body region BX1 is 1.3 or more, when the disposable diaper 1 is changed from a small size to a large size as the child grows and the child wears the diaper, the abdominal portion 3 can more reliably cover the abdomen, i.e., can more reliably cover the area up to the navel, even if the child is large.

[0087] 7 is a plan view of an example of the configuration of a disposable diaper 1 according to the embodiment in an unfolded state. The back section 2 has an absorber presence region AY2 and an absorber non-presence region AY1 in the longitudinal direction L. The absorber presence region AY2 is a region in the back section 2 where the absorbent core 8b is present in the longitudinal direction L. The absorber presence region AY2 can also be said to be a region that overlaps with the absorbent core 8b in the back section 2 in the thickness direction T in the longitudinal direction L. The length LAy2 of the absorber presence region AY2 in the longitudinal direction L is the length in the longitudinal direction L of the region where the absorbent core 8b and the back section 2 overlap in the thickness direction T in the longitudinal direction L. The length in the width direction W of the absorber presence region AY2 is the same as the length WWA of the back section 2 in the width direction W. On the other hand, the absorber non-presence region AY1 is located outside the absorber presence region AY2 and is a region where no absorbent core 8b is present. The absorbent-free region AY1 can also be said to be a region that does not overlap in the thickness direction T with the absorbent core 8b in the back section 2 in the longitudinal direction L. In the absorbent-free region AY1, the length LAy1 in the longitudinal direction L is the length in the longitudinal direction L of the region where the absorbent core 8b and the back section 2 do not overlap in the thickness direction T, and is the length obtained by subtracting the length LAy2 in the longitudinal direction L of the absorbent-containing region AY2 from the length LLA in the longitudinal direction L of the back section 2. The length in the width direction W is the same as the length WWA in the width direction W of the back section 2.

[0088] Similarly, in the state of Figure 7, the abdominal portion 3 has an absorbent body presence region BY2 and an absorbent body non-presence region BY1 in the longitudinal direction L. The absorbent body presence region BY2 is a region in the abdominal portion 3 where the absorbent core 8b is present in the longitudinal direction L. The absorbent body presence region BY2 can also be said to be a region that overlaps with the absorbent core 8b in the abdominal portion 3 in the thickness direction T in the longitudinal direction L. The length LBy2 in the longitudinal direction L of the absorbent body presence region BY2 is the length in the longitudinal direction L of the region where the absorbent core 8b and the abdominal portion 3 overlap in the thickness direction T in the longitudinal direction L. The length in the width direction W of the absorbent body presence region BY2 is the same as the length WWB in the width direction W of the abdominal portion 3. On the other hand, the absorbent body non-presence region BY1 is located outside the absorbent body presence region BY2 and is a region where no absorbent core 8b is present. The absorbent-free region BY1 can also be said to be a region that does not overlap in the thickness direction T with the absorbent core 8b in the abdominal portion 3 in the longitudinal direction L. In the absorbent-free region BY1, the length LBy1 in the longitudinal direction L is the length in the longitudinal direction L of the region where the absorbent core 8b and the abdominal portion 3 do not overlap in the thickness direction T, and is the length obtained by subtracting the length LBy2 in the longitudinal direction L of the absorbent-containing region BY2 from the length LLB in the longitudinal direction L of the abdominal portion 3. The length in the width direction W is the same as the length WWB in the width direction W of the abdominal portion 3.

[0089] In a preferred aspect of this embodiment, the ratio of the lengths LAy1, LBy1 of the absorber-free regions AY1, BY1 in the longitudinal direction L to the length LLO in the longitudinal direction L in each of the multiple types of disposable diapers 1 in the unfolded state is 29% or more. This makes it easier to grasp the absorber-free regions AY1, BY1. As a result, when putting the disposable diaper 1 on a baby, the absorber-free regions AY1, BY1 can be grasped and easily spread forward and backward, thereby easily widening the leg openings. Therefore, the inner thighs are less likely to get caught in the leg openings, making it easier to pull the diaper up to the appropriate position.

[0090] In a preferred aspect of this embodiment, the disposable diaper 1 further comprises a sheet-like elastic member 50 located in the main body non-existence areas AX1, BX1 in at least one of the abdominal section 3 and the back section 2 and extending along the width direction W. The sheet-like elastic member 50 may be partially or entirely included in the main body existence areas AX2, BX2 in at least one of the abdominal section 3 and the back section 2. This allows the entire waist section WP (torso-surrounding section) formed by the abdominal section 3 and the back section 2 to tighten the body over a surface area. This improves the fit of the disposable diaper 1 and also makes it difficult for the waist section WP to slip down after the abdominal section 3 has sufficiently covered the abdomen, i.e., after covering up to above the navel.

[0091] 8 is a plan view of an example of the configuration of a disposable diaper 1 according to the embodiment in an unfolded state. Consider the case where each of the pair of side joints SC (dorsal joints 2a) in the back portion 2 is virtually divided into four equal parts in the longitudinal direction L. The ranges from the outer edge to the inner edge of the side joints SC (dorsal joints 2a) in the longitudinal direction L are designated as a first region S1 (2a1), a second region S2 (2a2), a third region S3 (2a3), and a fourth region S4 (2a4), respectively. In this case, the regions between the pair of first joints S1 (2a1), the pair of second joints S2 (2a2), the pair of third joints S3 (2a3), and the pair of fourth joints S4 (2a4) in the pair of side joints SC (dorsal joints 2a) are designated as a first region AA1, a second region AA2, a third region AA3, and a fourth region AA4, respectively. These regions can be said to be regions obtained by dividing the back portion 2 into four in the longitudinal direction L.

[0092] Similarly, in the ventral portion 3, consider virtually dividing each of the pair of side joints SC (ventral joints 3a) into four equal parts in the longitudinal direction L. The ranges from the outer edge to the inner edge of the side joints SC (dorsal joints 2a) in the longitudinal direction L are defined as a first range S1 (3a1), a second range S2 (3a2), a third range S3 (3a3), and a fourth range S4 (3a4), respectively. In this case, in the pair of side joints SC (ventral joints 3a), the region located between the pair of first ranges S1 (3a1), the region located between the pair of second ranges S2 (3a2), the region located between the pair of third ranges S3 (3a3), and the region located between the pair of fourth ranges S4 (3a4) are defined as a first region BA1, a second region BA2, a third region BA3, and a fourth region BA4, respectively. These regions can be said to be the regions obtained by dividing the ventral portion 3 into four parts in the longitudinal direction L.

[0093] Fig. 9 is a partial side view of an example configuration of a disposable diaper according to an embodiment. This figure shows the vicinity of one of a pair of side joints SC where a pair of ventral joints 3a and a pair of back joints 2a of the disposable diaper 1 are joined together. Here, the fourth region AA4 and the fourth region BA4 are adjacent to each other via the side joint SC. Similarly, the third region AA3 and the third region BA3 are adjacent to each other via the side joint SC. The second region AA2 and the second region BA2 are adjacent to each other via the side joint SC. The first region AA1 and the first region BA1 are adjacent to each other via the side joint SC.

[0094] In a preferred aspect of this embodiment, in the disposable diaper 1 having the above-described configuration, the tensile stress in the width direction W in the fourth region BA4, AA4 in each of the abdominal portion 3 and the back portion 2 is smaller than the tensile stress in the width direction W in each of the first region BA1, AA1 to the third region BA3, AA3 in each of the abdominal portion 3 and the back portion 2. That is, in the abdominal portion 3, the tensile stress in the width direction W in the fourth region BA4 is smaller than the tensile stress in the width direction W in each of the first region BA1 to the third region BA3. Similarly, in the back portion 2, the tensile stress in the width direction W in the fourth region AA4 is smaller than the tensile stress in the width direction W in each of the first region AA1 to the third region AA3.

[0095] Thus, in the disposable diaper 1 product group, the tensile stress in the width direction W of the fourth region BA4, AA4, which is the innermost region in the longitudinal direction L (lower, near the leg opening LH), is smaller than the tensile stress in the width direction W of the other first region BA1, AA1 to third region BA3, AA3. Therefore, when putting the disposable diaper 1 on a child, the lowermost portions in the longitudinal direction L (leg openings LH) of the abdominal portion 3 and the dorsal portion 2, through which the legs pass, can be easily expanded. This makes it less likely for the leg openings LH to get caught on the child's inner thighs, making it easier to pull up the disposable diaper 1. This allows the abdomen to be sufficiently covered, i.e., covering up to the navel.

[0096] In a preferred aspect of this embodiment, in the disposable diaper 1 having the above-described configuration, the tensile stress in the width direction W of the fourth region BA4 in the abdominal portion 3 is greater than the tensile stress in the width direction W of the fourth region AA4 in the back portion 2. Therefore, the fourth region BA4 of the abdominal portion 3 can be contracted in the width direction W, and the fourth region AA4 of the back portion 2 can be pulled toward the abdominal portion 3 in the width direction W. Here, the fourth region AA4 is a portion of the back main body portion 21 adjacent to the buttocks-covering portion 30 (back-side extension portion 20). Therefore, by pulling the fourth region AA4 toward the abdominal portion 3 in the width direction W, the buttocks-covering portion 30 can be pulled toward the abdominal portion 3 in the width direction W. This allows the buttocks-covering portion 30 to be used widely in the width direction W, and allows the buttocks-covering portion 30 to adequately cover and conceal the buttocks. The tensile stress of the fourth region BA4 is preferably 2 to 10 times, more preferably 3 to 8 times, and even more preferably 4 to 6 times the tensile stress of the fourth region AA4. Specific values ​​vary depending on the size of the product, the intended wearer, and the like, but the tensile stress of the fourth region BA4 is, for example, 6 to 25 N / m, preferably 8 to 20 N / m, and more preferably 10 to 15 N / m.

[0097] However, the following method may be used to measure the tensile stress. (1) Prepare a tensile testing machine (Universal Material Testing Machine Model No. 5565, manufactured by Instron Corporation). (2) Prepare a test specimen. For example, when measuring the tensile stress of each of the first region BA1 to the fourth region BA4 of the abdominal portion 3, remove the abdominal portion 3 from the disposable diaper 1, and cut out the first region BA1 to the fourth region BA4 from the abdominal portion 3 to prepare the test specimen. When measuring the tensile stress of each of the first region AA1 to the fourth region AA4 of the back portion 2, remove the back portion 2 from the disposable diaper 1, and cut out the first region BA1 to the fourth region BA4 from the back portion 2 to prepare the test specimen. (3) Clamp one end of the test specimen in the upper zipper. (4) Raise the upper zipper until the test specimen hangs above the lower zipper and no longer touches the lower bar. (5) Correct the force to zero and remove the weight of the test specimen. (6) Lower the upper chuck to the initial chuck distance (20 mm). (7) Clamp the other end of the test specimen in the lower chuck. The area between the upper and lower chucks is the measurement area. (8) Start the test and move the upper chuck upward at 100 mm / min until it reaches 80% of the template dimension (maximum stretched state = unfolded state). (9) Then, immediately return the upper chuck to the initial chuck distance at the same speed. (10) Record the force at 80% of the template dimension (maximum stretched state). (11) Calculate the average tension (N) of the n=5 measurements measured in (10) above. For each of the first to fourth regions BA1 to BA4 of the test specimen, divide this average tension by their length in the longitudinal direction L to obtain their tensile stress. Similarly, in the case of each of the first to fourth areas AA1 to AA4 of the test piece, the average tension is divided by the length in the longitudinal direction L to obtain the tensile stress thereof.

[0098] -1 The tensile stress may be measured by the method described in paragraphs 0048 to 0060 of Patent Document 1. This method was adopted in the present embodiment. However, the front waist zone 102, the front distal abdominal zone 104, the front proximal abdominal zone 106, and the front leg zone 108 in Patent Document 1 correspond to the first region BA1, the second region BA2, the third region BA3, and the fourth region BA4 of the abdominal portion 3, respectively. On the other hand, the back waist zone 102, the rear distal abdominal zone 104, the rear proximal abdominal zone 106, and the rear leg zone 108 in Patent Document 1 correspond to the first region AA1, the second region AA2, the third region AA3, and the fourth region AA4 of the back portion 2, respectively.

[0099] In a preferred aspect of this embodiment, the number of waist elastic members 12 (12a, 12b) per unit length in the longitudinal direction L in the back portion 2 is fewer in the fourth region AA4 than in the third region AA3. Here, since the lengths in the longitudinal direction L of the fourth region AA4 and the third region AA3 are the same, if the number of waist elastic members 12 in a region is relatively fewer, the number of waist elastic members 12 per unit length in the longitudinal direction L of that region will also be relatively fewer. Therefore, in other words, the preferred aspect is that the number of waist elastic members 12 (12a, 12b) in the fourth region AA4 is fewer than that in the third region AA3. In the examples shown in Figures 3 and 8, the fourth region AA4 has two elastic members, while the third region AA3 has five.

[0100] Thus, in the disposable diaper 1 product group, the number of waist elastic members 12 (12a, 12b) per unit length in the longitudinal direction L is smaller in the fourth region AA4, which is the innermost region in the longitudinal direction L (lower, near the leg opening LH), than in the third region AA3 above it. Therefore, when putting the disposable diaper 1 on a child, the lowermost portions in the longitudinal direction L (leg openings LH) of the abdominal and dorsal portions 3 and 2, through which the legs pass, can be easily expanded. This makes it less likely for the leg openings LH to get caught on the child's inner thighs, making it easier to pull up the disposable diaper 1. This allows the abdomen to be sufficiently covered, i.e., covering the area above the navel.

[0101] In a preferred aspect of this embodiment, the waist elastic members 13 in the fourth region BA4 of the abdominal portion 3 and the waist elastic members 12a in the fourth region AA4 of the back portion 2 are not aligned in the longitudinal direction L. This configuration reduces the strong tightening force that would otherwise be generated when the longitudinal direction L of the waist elastic members 13 in the abdominal portion 3 and the longitudinal direction L of the waist elastic members 12a in the back portion 2 are aligned in the fourth regions BA4 and AA4. This reduces the tightening force at the lowest portions (leg openings) of the abdominal portion 3 and the back portion 2 in the longitudinal direction L through which the legs pass. This reduces the likelihood that the leg openings LH will get caught on the child's inner thighs, making it easier to pull up the disposable diaper 1. This ensures that the abdomen is adequately covered, i.e., the diaper can be extended up to above the navel. In addition, some of the waist elastic members 13 in the fourth region BA4 of the abdominal portion 3 and some of the waist elastic members 12a in the fourth region AA4 of the back portion 2 may be positioned at the same position in the longitudinal direction L as each other.

[0102] FIG. 10 is a partial plan view showing an example of the configuration of a disposable diaper 1 according to this embodiment in an unfolded state. This view is an enlarged view of the area near the buttocks-covering portion 30 and can also be considered a view showing the stretched state. Each of the pair of leg gathers 5 is divided in half in the width direction W into an outer area GOA and an inner area GIA. In this embodiment, as a preferred aspect, the leg elastic members 5a located in the outer area GOA have a lower tensile stress than those located in the inner area GIA. In other words, the total elastic force of the leg elastic members 5a located in the outer area GOA is smaller than the total elastic force of the leg elastic members 5a located in the side area GIA. In the example shown in this figure, there are three leg elastic members 5a located in the inner area GIA, but there are two leg elastic members 5a located in the outer area GOA (one of which is thin), which can be said to have a lower tensile stress (the total elastic force is small). The tensile stress may be measured by using the outer area GOA and the inner area GIA of the leg gathered portion 5 as test pieces in the above-mentioned measurement method.

[0103] The elastic force of the elastic member is measured as follows: (1) With the disposable diaper in an unfolded state, a mark is made at a predetermined length L (e.g., 50 mm) of the elastic member. (2) The elastic member is removed from the disposable diaper using a cold spray or the like. (3) Using a tensile tester (Instron Corporation, Universal Material Testing Machine, Model No. 5565), the thread-like elastic member in its natural state is pulled at a speed of 100 mm / min, and the tensile strength of the elastic member at the predetermined length is read. (4) Using different disposable diapers, steps (1) to (3) are repeated, and the tensile strength is measured at 10 points, and the average of the measurements is taken as the elastic force of the elastic member.

[0104] In this way, in the disposable diaper 1 product group, the tensile stress in the outer region GOA of the leg gathers 5 near the legs is low, so when putting the disposable diaper 1 on a child, the lower end (leg opening LH) through which the legs pass can be easily expanded. This makes it less likely for the leg opening LH to get caught on the child's inner thighs, making it easier to pull up the disposable diaper 1. This allows the abdomen to be sufficiently covered, i.e., covering up to above the navel.

[0105] Next, a method for manufacturing a product group of disposable diapers 1 consisting of a plurality of different sizes of disposable diapers 1 will be described. The manufacturing method includes a first step, a second step, and a third step. The first step is a step of manufacturing one (e.g., size M) of a small-sized disposable diaper 1 (e.g., size M) and a large-sized disposable diaper 1 (e.g., size L) using predetermined equipment. The second step is a step of changing the settings of the positions at which the ventral section 3 and the dorsal section 2 are connected to the absorbent main body 4 using the predetermined equipment. The third step is a step of manufacturing the other (e.g., size L) of the small-sized disposable diapers 1 (e.g., size M) and the large-sized disposable diapers 1 (e.g., size L) using the predetermined equipment. However, the configuration of the manufactured disposable diapers 1 is as described above.

[0106] FIG. 12 is a schematic diagram illustrating an example of a manufacturing method for a disposable diaper 1 according to the embodiment. This diagram illustrates first and third steps performed in a predetermined facility. In the first step, a continuous sheet member 101 used as the sheet member in the ventral portion 3 and the back portion 2 of the disposable diaper 1 is conveyed in the conveying direction MD. The continuous sheet member 101 is formed by laminating continuous sheet members for the skin side and the non-skin side, and sandwiches the waist elastic members 112, 113 used as the waist elastic members 12, 13 of the disposable diaper 1. The width of the continuous sheet member 101 in the cross direction CD is the sum of the length LLB of the ventral portion 3 in the longitudinal direction L and the length LLA of the back portion 2 in the longitudinal direction L. The continuous sheet member 101 is manufactured in a previous process.

[0107] Next, the continuous sheet member 101 is conveyed in the conveying direction MD and divided into two parts approximately at the center of its width in the transverse direction CD. One of the divided parts becomes the back-side continuous sheet member 102 used in the back-side portion 2, and the other becomes the belly-side continuous sheet member 103 used in the belly-side portion 3. Therefore, even for disposable diapers 1 of different sizes, the sum of the length LLB of the belly-side portion 3 in the longitudinal direction L and the length LLA of the back-side portion 2 in the longitudinal direction L remains the same. Thereafter, the back-side continuous sheet member 102 and the belly-side continuous sheet member 103 are conveyed in parallel in the conveying direction MD while maintaining a predetermined distance IM in the transverse direction CD. The distance IM is the length LLC of the crotch region 4a in the longitudinal direction L, i.e., the distance between the belly-side portion 3 and the back-side portion 2.

[0108] Next, while the back-side continuous sheet member 102 and the ventral-side continuous sheet member 103 are conveyed in parallel in the conveying direction MD, adhesive 105 is applied to predetermined positions on the inside in the cross direction CD of each of the back-side continuous sheet member 102 and the ventral-side continuous sheet member 103. The adhesive 105 is applied intermittently in the conveying direction MD at predetermined intervals IC. The intervals IC are the length obtained by subtracting the length in the width direction W of the absorbent main body 4 from the length WWA of the width direction W of the back-side portion 2 (or the length obtained by subtracting the length in the width direction W of the absorbent main body 4 from the length WWB of the width direction W of the ventral portion 3). The length of the adhesive 105 in the MD direction is the length in the width direction W of the absorbent main body 4.

[0109] Next, while the back-side continuous sheet member 102 and the ventral-side continuous sheet member 103 are transported in parallel in the machine direction MD, an absorbent body 104 to be used in the absorbent body 4 of the disposable diaper 1 is connected to them at a predetermined position on the inside in the cross direction CD via an adhesive 105. The absorbent body 104 is manufactured in a separate, previous process.

[0110] Next, the back-side continuous sheet member 102 and the ventral-side continuous sheet member 103 are cut in the cross direction CD at positions Q of intervals IP in the conveying direction MD while being conveyed in parallel in the conveying direction MD. The intervals IP are the length WWA of the width direction W of the back-side portion 2 (or the length WWB of the width direction W of the ventral-side portion 3). The positions Q are the center positions of the intervals IC. In this manner, a disposable diaper 1 in an unfolded state is manufactured, which includes the back-side portion 2, the ventral-side portion 3, and the absorbent main body 4. Thereafter, both side edges in the width direction W of the ventral-side portion 3 and both side edges in the width direction W of the back-side portion 2 are joined at a pair of side joining portions SC, thereby manufacturing a pants-type disposable diaper 1.

[0111] Next, in the second step, the interval IM is changed to match the size of the next disposable diaper 1 to be manufactured in the specified facility. For example, to reduce the size, the interval IM is reduced, and to increase the size, the interval IM is increased. As a result, the length LLC in the longitudinal direction L of the crotch region 4a of the next disposable diaper 1 to be manufactured corresponds to the next size. Accordingly, the length LAx1 in the longitudinal direction L of the main body non-existence region AX1 and the length LBx1 in the longitudinal direction L of the main body non-existence region BX1 also correspond to the next size.

[0112] When dividing the continuous sheet member 101 into two halves at approximately the center of its width in the transverse direction CD, the position of the center in the transverse direction CD may be changed. In this case, the ratio between the length LAx1 of the main body non-existence region AX1 in the longitudinal direction L and the length LBx1 of the main body non-existence region BX1 in the longitudinal direction L can be adjusted for each size. The position of the interval IC may also be changed, and therefore the position of the interval IP may also be changed. For example, when reducing the size, the interval IC, and therefore the interval IP, are reduced; when increasing the size, the interval IC, and therefore the interval IP, are increased. The type, material, and characteristics of the waist-surrounding elastic members 112, 113 used in the waist-surrounding elastic members 12, 13 of the disposable diaper 1 may also be changed. For example, when reducing the size, the elasticity and / or the number of the waist-surrounding elastic members 13, 12 are increased; and when increasing the size, the elasticity and / or the number of the waist-surrounding elastic members 13, 12 are decreased.

[0113] Next, after some of the intervals are changed in accordance with the size change in a predetermined facility, a third step similar to the first step described above and shown in Fig. 12 is carried out. In this way, a product group of disposable diapers 1 consisting of a plurality of types of disposable diapers 1 of different sizes is manufactured.

[0114] In this way, the method for manufacturing a group of disposable diapers 1 allows adjacent sizes of disposable diapers 1 to be manufactured using a single predetermined facility. This makes it possible to efficiently manufacture a group of disposable diapers 1 made up of multiple types of disposable diapers 1 of different sizes. The manufactured disposable diapers 1 of each size have the various configurations described above, and are therefore able to achieve the various effects described above.

[0115] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0116] (1) Samples Three sets of disposable diapers, each consisting of a small-sized M-size disposable diaper and a large-sized L-size disposable diaper, were prepared as adjacent sizes of disposable diapers in the embodiment. These were designated "Example 1" to "Example 3." However, the disposable diapers of Examples 1 and 2 were disposable diapers designed to be smaller, while the disposable diaper of Example 3 was a disposable diaper designed to be larger. In addition, four sets of disposable diapers, each consisting of a small-sized M-size disposable diaper and a large-sized L-size disposable diaper, were prepared as adjacent sizes of commercially available disposable diapers. These were designated "Comparative Example 1" to "Comparative Example 4."

[0117] The increase rate (%), second increase rate (%), third increase rate (%), and fourth increase rate (%) in each example and comparative example were as follows: Example 1: 4.1%, 5.4%, 4.4%, 5.5% Example 2: 6.1%, 8.2%, 6.5%, 8.2% Example 3: 39.4%, 68.4%, 65.0%, 68.4% Comparative Example 1: 1.2%, 1.5%, 1.7%, 1.6% Comparative Example 2: 3.2%, 4.2%, 3.3%, 4.2% Comparative Example 3: 3.8%, 4.5%, 4.0%, 4.5% Comparative Example 4: 4.0%, 5.3%, 4.2%, 5.3%

[0118] (2) Evaluation The disposable diapers of Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated for whether the inner thighs of the child tend to get caught in the leg openings and whether the child's abdomen can be sufficiently covered when the size of the disposable diaper was changed from M to L. The evaluation method involved putting L-size diapers on infants weighing 9 to 12 kg (from the later period of using M size to the early period of using L size), and evaluating the diapers from the viewpoints of (i) whether they cover the navel (good: covers; bad: does not cover), (ii) whether they slip down after being pulled up to the navel (good: does not slip down; bad: slips down), and (iii) whether they get caught around the legs (good: does not get caught; bad: gets caught).

[0119] The above evaluations yielded the results shown in Table 1 below, confirming the superiority of the disposable diapers of the examples.

[0120] The disposable diaper of the present invention is not limited to the above-described embodiment, and can be appropriately combined with or modified in accordance with known techniques, etc., within the scope of the object and spirit of the present invention.

[0121] REFERENCE SIGNS LIST 1 Disposable diaper 2 Back portion 3 Abdominal portion 4 Absorbent body 4a Crotch region LLC Longitudinal length of crotch region AX1, BX1 Non-main body region LAx1, LBx1 Longitudinal length of non-main body region LLO Longitudinal length of disposable diaper in unfolded state

Claims

1. A disposable diaper product group consisting of a plurality of types of disposable diapers of different sizes, wherein the disposable diapers have, in an unfolded state, longitudinal, width, and thickness directions which are orthogonal to one another, and comprise a ventral section covering the ventral side of a wearer, a dorsal section covering the dorsal side, and an absorbent main body covering the wearer's crotch and including an absorbent body, the front and rear ends of the absorbent main body in the longitudinal direction being connected to central sections in the width direction of the ventral section and the dorsal section, respectively, and are formed by joining both side edges in the width direction of the ventral section to both side edges in the width direction of the dorsal section with a pair of side joining sections, and each of the ventral section and the dorsal section has, in the longitudinal direction, a main body presence region in which the absorbent main body is present, and a main body absence region located outside the main body presence region and in which the absorbent main body is not present, In disposable diapers of adjacent sizes among the plurality of types of disposable diapers, the longitudinal length of the crotch region of the absorbent main body that does not overlap with the ventral side portion and the dorsal side portion is longer in the disposable diaper of a larger size than in the disposable diaper of a smaller size, and the increase in the longitudinal length from the main body non-existence region of the disposable diaper of a smaller size to the main body non-existence region of the disposable diaper of a larger size is set so that the increase rate represented by the following formula is in the range of 4.1 to 39.4%: Increase rate (%) = (the increase amount) / (the longitudinal length of the disposable diaper of a larger size in an unfolded state) x 100.

2. A group of disposable diapers according to claim 1, wherein in each of the adjacent sizes of disposable diapers, the sum of the longitudinal length of the ventral portion and the longitudinal length of the dorsal portion is the same, the widthwise length of the ventral portion and the widthwise length of the dorsal portion are the same, and the disposable diaper of the larger size has a longer longitudinal length in an unfolded state than the disposable diaper of the smaller size.

3. A group of disposable diapers according to claim 1 or 2, wherein each of the ventral portion and the dorsal portion has a plurality of waist elastic members extending along the width direction and arranged at intervals in the longitudinal direction, and in each of the disposable diapers of adjacent sizes, the sum of the longitudinal length of the ventral portion and the longitudinal length of the dorsal portion is the same, the widthwise length of the ventral portion and the widthwise length of the dorsal portion are the same, and the stretch ratio of the plurality of waist elastic members is lower in the larger sized disposable diaper than in the smaller sized disposable diaper.

4. A group of disposable diapers according to any one of claims 1 to 3, wherein each of the ventral portion and the dorsal portion has a plurality of waist elastic members extending along the width direction and arranged at intervals in the longitudinal direction, and in each of the disposable diapers of adjacent sizes, the sum of the longitudinal length of the ventral portion and the longitudinal length of the dorsal portion is the same, the widthwise length of the ventral portion and the widthwise length of the dorsal portion are the same, and the larger size disposable diaper has a smaller number of the waist elastic members than the smaller size disposable diaper.

5. A group of disposable diaper products according to any one of claims 1 to 4, wherein the longitudinal length of the main body-free region of the abdominal side portion in each of the plurality of types of disposable diapers is 21 mm or more.

6. A group of disposable diaper products according to any one of claims 1 to 5, wherein the ratio of the non-main body area in the abdominal side of the larger-sized disposable diaper to the non-main body area in the abdominal side of the smaller-sized disposable diaper is 1.3 or more.

7. A group of disposable diapers according to any one of claims 1 to 6, wherein the absorbent main body includes an absorbent body having an absorbent core, and each of the ventral side portion and the dorsal side portion has, in the longitudinal direction, an absorbent body presence region in which the absorbent core is present, and an absorbent body non-presence region located outside the absorbent body presence region and in which the absorbent core is not present, and the ratio of the longitudinal length of the absorbent body non-presence region to the longitudinal length of each of the plurality of types of disposable diapers in an unfolded state is 29% or more.

8. A disposable diaper product group according to any one of claims 1 to 7, further comprising a sheet-like stretchable member located in the main body absent region of at least one of the ventral side portion and the dorsal side portion and extending along the width direction.

9. A group of disposable diaper products according to any one of claims 1 to 8, wherein in each of the plurality of types of disposable diapers, when the regions obtained by dividing each of the ventral portion and the dorsal portion in the longitudinal direction into four regions are designated as first to fourth regions in order from the outside in the longitudinal direction, the tensile stress in the width direction in the fourth region in each of the ventral portion and the dorsal portion is smaller than the tensile stress in the width direction in each of the first to third regions in each of the ventral portion and the dorsal portion.

10. A group of disposable diapers according to any one of claims 1 to 9, wherein each of the ventral and dorsal sections has a plurality of waist elastic members extending in the width direction and arranged at intervals in the longitudinal direction, and in each of the plurality of types of disposable diapers, when the ventral and dorsal sections are each divided into four regions in the longitudinal direction and designated as first to fourth regions in order from the outside in the longitudinal direction, the number of waist elastic members per unit length in the longitudinal direction in the fourth region is smaller than that in the third region.

11. A disposable diaper product group according to any one of claims 1 to 10, wherein each of the ventral portion and the dorsal portion has a plurality of waist elastic members extending along the width direction and arranged at intervals in the longitudinal direction, and in each of the plurality of types of disposable diapers, when the ventral portion and the dorsal portion are each divided into four regions in the longitudinal direction, designated as first region to fourth region from the outside in the longitudinal direction, in the fourth region, the positions of the waist elastic members in the ventral portion and the dorsal portion do not coincide with each other in the longitudinal direction.

12. A group of disposable diaper products according to any one of claims 1 to 11, wherein the absorbent main body comprises: an absorbent main body central portion located in the central portion in the width direction and having an absorbent body; and a pair of leg gather portions located at both ends in the width direction and having a plurality of leg elastic members extending along the longitudinal direction; and when each of the pair of leg gather portions is divided in half in the width direction into an outer outer region and an inner inner region, those of the plurality of leg elastic members located in the outer regions have a lower tensile stress than those located in the inner regions.

13. A disposable diaper product group according to any one of claims 1 to 12, wherein the increase in length in the longitudinal direction from the non-main body region of the smaller sized disposable diaper to the non-main body region of the larger sized disposable diaper among adjacent sizes of the plurality of types of disposable diapers is further set so that a second increase rate, as expressed by the following formula, is in the range of 5.4 to 68.4%: Second increase rate (%) = (amount of increase) / (longitudinal length of the absorbent main body of the larger sized disposable diaper) x 100.

14. A disposable diaper product group according to any one of claims 1 to 13, wherein the increase in longitudinal length from the non-main body region of the smaller sized disposable diaper to the non-main body region of the larger sized disposable diaper of adjacent sizes among the plurality of types of disposable diapers is set so that the third increase rate, as expressed by the following formula, is in the range of 4.4 to 65.0%: Third increase rate (%) = (amount of increase) / (longitudinal length of the smaller sized disposable diaper in its unfolded state) x 100.

15. A disposable diaper product group according to any one of claims 1 to 14, wherein the increase in longitudinal length from the non-main body region of the smaller sized disposable diaper to the non-main body region of the larger sized disposable diaper of adjacent sizes among the plurality of types of disposable diapers is set so that a fourth increase rate, as expressed by the following formula, is in the range of 5.5 to 68.4%: Fourth increase rate (%) = (amount of increase) / (longitudinal length of the absorbent main body of the smaller sized disposable diaper) x 100.

16. A method for manufacturing a group of disposable diaper products consisting of a plurality of types of disposable diapers of different sizes, wherein the disposable diapers have, in an unfolded state, longitudinal, width, and thickness directions which are orthogonal to one another, and comprise a ventral portion covering the ventral side of a wearer, a dorsal portion covering the dorsal side, and an absorbent main body covering the crotch of the wearer and including an absorbent body, the absorbent main body has front and rear ends in the longitudinal direction which are central in the width direction of the ventral portion and the dorsal portion, respectively, and is formed by joining both side edges in the width direction of the ventral portion to both side edges in the width direction of the dorsal portion with a pair of side joining portions, and each of the ventral portion and the dorsal portion has, in the longitudinal direction, a main body presence region in which the absorbent main body is present, and a main body absence region located outside the main body presence region and in which the absorbent main body is not present, the longitudinal length of the crotch region of the absorbent main body that does not overlap with the ventral portion and the dorsal portion is longer in the larger size disposable diaper than in the smaller size disposable diaper, and an increase in the longitudinal length of adjacent sizes of the plurality of types of disposable diapers from the main body non-existence region of the smaller size disposable diaper to the main body non-existence region of the larger size disposable diaper is set so that the increase rate, as expressed by the following formula, is in the range of 4.1 to 39.4%: Increase rate (%) = (the increase amount) / (the longitudinal length of the larger size disposable diaper in an unfolded state) x 100, and the manufacturing method comprises: a first step of manufacturing one of the small size disposable diaper and the large size disposable diaper using predetermined equipment; a second step of changing, in the predetermined equipment, the settings of the positions at which the ventral portion and the dorsal portion are connected to the absorbent main body; and a third step of manufacturing the other of the small size disposable diaper and the large size disposable diaper using the predetermined equipment. Manufacturing method for disposable diaper product line.

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