Pants-type absorbent article

Abstract

To provide an underpants type absorbent article that is suppressed in removal and cutting of elastic members included in a waist part and retains elasticity of the waist part while retaining flexibility of the waist part.SOLUTION: An underpants type absorbent article (1) connected by a side connection region (40) of an abdominal side waist part (20) and a back side waist part (30) is such that: the waist part sandwiches elastic members (23, 33) in a state of being shrunken in a left-right direction, and has a plurality of welding part pairs (50S) for restricting positions of the elastic members (23, 33); and the plurality of welding part pairs (50S) have first welding part pairs (50S1) adjacent in the inside in the left-right direction of the side connection region (40), and second welding part pairs (50S2) adjacent in the inside in the left-right direction of the first welding part pairs (50S1). When viewing the underpants type absorbent article (1) in a stretched state in a front-back direction, a center line of portions of the elastic members (23, 33) positioned in the side connection region (40) is inclined to a center line of the portions of the elastic members (23, 33) positioned between the first welding part pairs (50S1) and the second welding part pairs (50S2).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention provides For pants-type absorbent articles Regarding. [Background technology]

[0002] Patent Document 1 discloses a pants-type absorbent article in which both sides of a ventral section, which is located on the ventral side of a wearer, and both sides of a dorsal section, which is located on the dorsal side, are joined by a pair of side seals. The constituent sheets of the ventral section and the dorsal section are intermittently joined by a plurality of fused sections, and a thread-like elastic member disposed between the sheets passes between the plurality of fused sections aligned in the longitudinal direction. Furthermore, while the elastic member is fixed at a pair of outer fastening regions disposed at both lateral ends of the ventral section and the dorsal section, it is not fixed to any of the sheets between the pair of outer fastening regions. Therefore, when the elastic member contracts, the constituent sheets of the ventral section and the dorsal section expand between adjacent fused sections, forming a hollow space between the sheets. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 123549 Summary of the Invention [Problem to be solved by the invention]

[0004] The elastic members are generally fixed to the constituent sheets of the ventral and dorsal portions with adhesive. However, as in Patent Document 1, by not fixing the elastic members to the sheets with adhesive between the outer fixing regions of the ventral and dorsal portions, the flexibility of the ventral and dorsal portions (waistline portions) can be maintained. However, simply fixing both ends of the elastic members with adhesive, as in Patent Document 1, may cause the elastic members to come loose from the outer fixing regions due to the contractile force of the elastic members. Furthermore, in Patent Document 1, the side seals and fused portions are formed with an emphasis on the tearability of the side seals, so there is a risk that the elastic members may be cut when the side seals are formed. This would reduce the stretchability of the ventral and dorsal portions (waistline portions).

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a pants-type absorbent article in which the flexibility of the waist portion is maintained while preventing the elastic members of the waist portion from coming loose or breaking, thereby maintaining the stretchability of the waist portion. [Means for solving the problem]

[0006] The main invention to achieve the above object is: having vertical, horizontal, and front-to-rear directions that intersect with one another, an absorbent body; a waist portion in which the ventral waist portion and the back waist portion are joined at both ends in the left-right direction by a pair of side joining regions, In the waistband portion, a plurality of elastic members that stretch in the left-right direction are arranged side by side in the up-down direction between the skin side sheet and the non-skin side sheet that are joined by a plurality of welding portions, the plurality of welded portions are located on both sides of the elastic member in the up-down direction, sandwich the elastic member in a state contracted in the left-right direction, and include a plurality of pairs of welded portions that regulate the left-right position of the elastic member relative to the skin side sheet and the non-skin side sheet; The plurality of weld pairs are a first welded portion pair that is adjacent to the inner side of the side joint region on one side in the left-right direction and that sandwiches a first elastic member among the plurality of elastic members; a second pair of welded portions adjacent to the first pair of welded portions on the inner side in the left-right direction and sandwiching the first elastic member therebetween, When the pants-type absorbent article in a stretched state is viewed in the front-rear direction, a center line of a portion of the first elastic member located in the side joint region on one side in the left-right direction is inclined with respect to a center line of a portion of the first elastic member located between the first pair of welded portions and the second pair of welded portions, In the side joint region, a plurality of side joints are arranged side by side in the up-down direction, When viewed in the front-rear direction, a part of the first elastic member overlaps with the side joint portion. The pants-type absorbent article is characterized by the above. Other features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a pants-type absorbent article in which the flexibility of the waist portion is maintained while the elastic members of the waist portion are prevented from coming loose or breaking, thereby maintaining the stretchability of the waist portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view of a diaper 1. [Figure 2] 1 is a schematic plan view of a diaper 1 in an unfolded and stretched state, as seen from the wearer's skin side. [Figure 3] FIG. 3 is a schematic cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 4A is an explanatory diagram of a side joint region 40 and a welded portion row 50L provided in the waistband portion 2, and FIG. 4B is a schematic enlarged view of part B in FIG. 4A. [Figure 5] 5A and 5B are explanatory diagrams of the attachment function of the waist elastic member 23 (33). [Figure 6]6A and 6B are diagrams showing a state in which the end of the waist elastic member 23 (33) is in contact with the side joining portion 41. FIG. [Figure 7] 7A to 7C are diagrams showing the state in which the ends of the waist elastic members 23 (33) are sandwiched by the side joining portions 41. FIG. [Figure 8] 8A and 8B are diagrams showing modified examples of the side joint region 40. FIG. [Figure 9] 10 is an explanatory diagram of the length L1 in the up-down direction of the side joint portion 41. FIG. [Figure 10] 10A and 10B are diagrams showing modified examples of the welded portion 50. FIG. [Figure 11] FIG. 2 is an enlarged cross-sectional view of a waist elastic member 23 (33). [Figure 12] FIG. 2 is a diagram illustrating the flow of manufacturing the diaper 1 on a manufacturing line. [Figure 13] FIG. 13A is an explanatory diagram of the position where the side joint portion 41 is formed, and FIG. 13B is a schematic side view of the ultrasonic welding device 60 as seen from the CD direction. DETAILED DESCRIPTION OF THE INVENTION

[0009] At least the following matters will become clear from the description of this specification and the accompanying drawings. That is, a pants-type absorbent article having a vertical direction, a horizontal direction, and a front-rear direction which intersect with one another, and having an absorbent main body and a waist portion in which a ventral waist portion and a rear waist portion are joined at both ends in the horizontal direction by a pair of side joining regions, wherein in the waist portion, a plurality of elastic members which stretch in the horizontal direction are arranged side by side in the vertical direction between a skin side sheet and a non-skin side sheet which are joined by a plurality of welding parts, and the plurality of welding parts are located on both sides of the elastic members in the vertical direction, sandwich the elastic members in a state contracted in the horizontal direction, and adjust the horizontal positions of the elastic members relative to the skin side sheet and the non-skin side sheet. a plurality of pairs of welds that restrict the width of the side joint region on one side in the left-right direction, the plurality of pairs of welds including a first pair of welds adjacent to the inside of the side joint region on one side in the left-right direction and sandwiching a first elastic member among the plurality of elastic members, and a second pair of welds adjacent to the inside of the first pair of welds in the left-right direction and sandwiching the first elastic member, wherein when the pants-type absorbent article is in a stretched state and viewed in the front-to-back direction, the center line of the portion of the first elastic member located in the side joint region on one side in the left-to-right direction is inclined with respect to the center line of the portion of the first elastic member located between the first pair of welds and the second pair of welds.

[0010] In such a pants-type absorbent article, the position (movement) of the elastic members is restricted by the pair of welded portions, so adhesive for attaching the elastic members to the waistband can be eliminated or the amount of adhesive used can be reduced, thereby maintaining the flexibility of the waistband. Furthermore, the elastic members located in the side joint regions are tilted relative to the direction of the force that would cause the elastic members to slip out, making it difficult for the elastic members to slip out of the side joint regions. Therefore, the stretchability of the waistband is maintained.

[0011] A pants-type absorbent article as described above, characterized in that the first elastic member extends outward in the left-right direction beyond the side joint region on one side in the left-right direction.

[0012] In such a pants-type absorbent article, the elastic members are positioned across the entire left-right area of ​​the side joint region where the friction between the elastic members and the sheet is high, making it more difficult for the elastic members to slip out of the side joint region.

[0013] Such a pants-type absorbent article is characterized in that in the side joint region, multiple side joints are arranged in a row in the vertical direction, and in the side joint region on one side in the left-right direction, a portion of the first elastic member is in contact with the side joint.

[0014] In such a pants-type absorbent article, the center line of the elastic member located in the side joint region is likely to be inclined relative to the center line of the elastic member located between the first and second welded portions. Also, frictional force is generated between the elastic member and the side joint, making it more difficult for the elastic member to slip out of the side joint region.

[0015] Such a pants-type absorbent article is characterized in that in the side joint region, multiple side joints are arranged in a row in the vertical direction, and in the side joint region on one side in the left-right direction, a portion of the first elastic member is sandwiched between the skin-side sheet and the non-skin-side sheet by the side joints.

[0016] In such a pants-type absorbent article, the center line of the elastic member located in the side joint region is likely to be inclined relative to the center line of the elastic member located between the first and second welded portions. Also, since part of the elastic member is firmly sandwiched between the sheets at the side joint region, the elastic member is less likely to slip out of the side joint region.

[0017] Such a pants-type absorbent article is characterized in that in the side joint region on one side in the left-right direction, a portion of a second elastic member among the plurality of elastic members is in contact with the side joint.

[0018] According to such a pants-type absorbent article, the plurality of elastic members of the waist portion are less likely to slip out of the side joint regions, and the stretchability of the waist portion is better maintained.

[0019] The pants-type absorbent article is characterized in that a portion of the first elastic member is in contact with the side joint in the side joint region on the other side in the left-right direction.

[0020] According to such a pants-type absorbent article, the elastic members are less likely to slip out from the side joint regions on both the left and right sides.

[0021] A pants-type absorbent article characterized in that in the side joint region, multiple side joints are arranged in the vertical direction, and the vertical distance between the first welded pair and the side joints arranged in the left-right direction is shorter than the vertical distance between the first welded pair.

[0022] In such a pants-type absorbent article, multiple side joints tend to be located at positions that overlap vertically with the spaces between the first pairs of welded portions, which makes it easier for parts of the elastic members to come into contact with the side joints or to overlap with the side joints in the thickness direction, and the center lines of the elastic members located in the side joint regions tend to be inclined relative to the center lines of the elastic members located between the first and second pairs of welded portions.

[0023] A pants-type absorbent article as described above, characterized in that in the side joint region, a plurality of side joints are arranged in the vertical direction, and the vertical distance between the first welded pair and the side joints arranged in the left-right direction is equal to or greater than the vertical distance between the first welded pair.

[0024] According to such a pants-type absorbent article, the number of side joints can be reduced, and flexibility of the waist portion (side joint region) is better maintained.

[0025] Such a pants-type absorbent article is characterized in that in the side joint region, multiple rows of side joints, in which multiple side joints are lined up in the vertical direction, are lined up in the left-right direction, and the multiple rows of side joints are spaced apart in the left-right direction.

[0026] In this pants-type absorbent article, the length of the side joint region is increased in the left-right direction, allowing the length of the elastic member, which exerts a strong frictional force with the sheet, to be increased. This further prevents the elastic member from slipping out of the side joint region. Furthermore, the area ratio of the side joints in the side joint region is reduced, allowing the flexibility of the waistband (side joint region) to be maintained.

[0027] A pants-type absorbent article characterized in that in the side joint region, multiple rows of side joints, each with a plurality of side joints lined up in the vertical direction, are lined up in the left-right direction, the side joints of each of two rows of side joints adjacent to each other in the horizontal direction are offset in the vertical direction, and the vertical length between the side joint adjacent to the first welded pair in the horizontal direction and the side joint adjacent to the first welded pair in the horizontal direction but offset in the vertical direction from the side joint is smaller than the diameter of the first elastic member when contracted in the horizontal direction.

[0028] In such a pants-type absorbent article, the elastic members are more likely to come into contact with at least one of the side joints that are vertically shifted and laterally adjacent to each other, which makes it easier for the elastic members to tilt along the side joints, thereby further preventing the elastic members from slipping out of the side joint regions.

[0029] Such a pants-type absorbent article is characterized in that in the side joint region, multiple side joints are arranged in a row in the vertical direction, and the side joint region has a portion where the welded portion and the side joint overlap in the thickness direction of the waist portion.

[0030] In such a pants-type absorbent article, the side joints are likely to be positioned so as to overlap the elastic members passing between the pairs of welded portions, which makes it easier for parts of the elastic members to come into contact with the side joints or to overlap with the side joints in the thickness direction, and makes it easier for the center lines of the elastic members located in the side joint regions to be inclined relative to the center lines of the elastic members located between the first and second pairs of welded portions.

[0031] A pants-type absorbent article as described above, characterized in that in at least one of the pair of side joint regions, at least one of the elastic members of the ventral waist portion is arranged offset in the vertical direction from the elastic member of the dorsal waist portion.

[0032] In such a pants-type absorbent article, the convex pattern forming the side joints can prevent both the ventral elastic member and the dorsal elastic member from being cut, and the number of overlapping materials in the thickness direction at the positions where the side joints are formed can be reduced, allowing the materials (sheets) to be firmly joined at the side joints.

[0033] A pants-type absorbent article as described above, characterized in that in the side joint region, a plurality of side joints are arranged in a line in the vertical direction, and when the pants-type absorbent article is stretched to its maximum in the left-right direction, the extension ratio of the first elastic member is a times, the width of the first elastic member in the vertical direction is D mm, and the maximum extension ratio of the first elastic member alone is b times, the vertical length of the side joints aligned in the left-right direction with the first welded pair is D×b / a mm or less.

[0034] In such pants-type absorbent articles, the vertical length of the side joint tends to be less than the width (D x b / a (mm)) at which the elastic member can expand without breaking, thereby preventing the elastic member from being cut by the convex pattern forming the side joint.

[0035] Such a pants-type absorbent article is characterized in that the vertical distance between the two welded portions that constitute the welded portion pair is wider at the end portion on at least one side in the left-right direction than at the center portion in the left-right direction of the welded portion pair.

[0036] In such a pants-type absorbent article, the elastic members are more likely to move up and down at the left and right ends of the welded portions, and the elastic members are more likely to tilt slightly left and right along the ends of the welded portions, which makes it possible to prevent the elastic members from slipping out from between the pair of welded portions.

[0037] The pants-type absorbent article is characterized in that an oil is applied to at least a part of the surface of the elastic member.

[0038] In such a pants-type absorbent article, even if the elastic members are stepped on by the raised pattern forming the side joint area, the oil makes the elastic members slippery and they are easily pushed out of the raised pattern, making it difficult for the elastic members to be cut and preventing them from slipping out of the side joint area.

[0039] The pants-type absorbent article is characterized in that the elastic member is a thread-like elastic member formed by gathering a plurality of elastic fibers.

[0040] In such a pants-type absorbent article, the elastic members are less likely to be cut due to the convex patterns that form the side joints, and the elastic members can be prevented from slipping out of the side joint regions.

[0041] Further, there is provided a method for manufacturing a pants-type absorbent article having an absorbent main body and a waistline portion in which a ventral waistline portion and a dorsal waistline portion are joined at both ends in the left-right direction by a pair of side joining regions, the method comprising: arranging a plurality of continuums of elastic members stretched in the conveying direction in a direction intersecting the conveying direction between a continuum of skin side sheets and a continuum of non-skin side sheets that are continuous in a conveying direction corresponding to the left-right direction; and then, when forming a plurality of welds joining the continuum of skin side sheets and the continuum of non-skin side sheets, the method comprises arranging the welds on both sides of the continuum of elastic members in the intersecting direction, so that when the elastic members in the pants-type absorbent article contract in the left-right direction, the welds extend to the front of the continuum of skin side sheets. a step of forming a continuum of the ventral waistband section and a continuum of the dorsal waistband section by forming a plurality of pairs of welded portions that sandwich the elastic member and regulate the left-right position of the elastic member relative to the skin-side sheet and the non-skin-side sheet; and a step of forming the side joint region by arranging a plurality of side joints in the cross direction that join the continuum of the ventral waistband section and the continuum of the dorsal waistband section that are stacked in the thickness direction, wherein in the step of forming the side joint region, the side joints are formed so that, when the material is viewed in the front-to-back direction, the center lines of the side joints are offset from the center lines of the pairs of welded portions adjacent to the side joint region in the conveying direction.

[0042] This manufacturing method for pants-type absorbent articles can reduce the probability (area ratio) that the convex patterns forming the side joints overlap with the elastic members, making it difficult for the convex patterns forming the side joints to cut the elastic members and preventing the elastic members from slipping out of the side joint areas.

[0043] Further, there is provided a method for manufacturing a pants-type absorbent article having an absorbent main body and a waistline portion in which a ventral waistline portion and a dorsal waistline portion are joined at both ends in the left-right direction by a pair of side joining regions, the method comprising: arranging a plurality of continuums of elastic members stretched in the conveying direction between a continuum of skin side sheets and a continuum of non-skin side sheets, the continuum being continuous in a conveying direction corresponding to the left-right direction, in a direction intersecting the conveying direction; and then forming a plurality of welded portions joining the continuum of skin side sheets and the continuum of non-skin side sheets, the welded portions being arranged on both sides of the continuum of elastic members in the intersecting direction, and the elastic members in the pants-type absorbent article a step of forming a continuum of the ventral waistline section and a continuum of the dorsal waistline section by forming a plurality of pairs of welded portions that sandwich the elastic members when contracted in the left-right direction and regulate the left-right position of the elastic members relative to the skin-side sheet and the non-skin-side sheet; and a step of forming the side joint region by arranging a plurality of side joint regions in the cross direction that join the continuum of the ventral waistline section and the continuum of the dorsal waistline section that are stacked in the thickness direction, wherein in the step of forming the side joint region, the side joint regions are formed while displacing the position in the cross direction of the continuum of the elastic members that is stretched in the conveying direction.

[0044] According to this manufacturing method for pants-type absorbent articles, the elastic members can be pushed out from the convex patterns that form the side joints, making it difficult for the elastic members to be cut by the convex patterns that form the side joints, and preventing the elastic members from slipping out of the side joint regions.

[0045] A method for manufacturing such pants-type absorbent articles, characterized in that in the step of forming the side joint regions, the side joints are formed by ultrasonic welding.

[0046] According to this method for manufacturing pants-type absorbent articles, the vibrations of ultrasonic welding make it easier for the elastic members to move, which makes it easier for the elastic members to be pushed out of the convex patterns that form the side joints (easier for the positions of the elastic members in the cross direction to be displaced), thereby preventing the elastic members from breaking.

[0047] === Implementation form === The following description will be given taking as an example a pants-type disposable diaper 1 (hereinafter also referred to as "diaper") for babies as an example of a pants-type absorbent article according to the present invention. However, the pants-type absorbent article according to the present invention is not limited to the above, and can also be applied to pants-type disposable diapers for adults, shorts-type sanitary napkins, etc.

[0048] <<Basic structure of pants-type disposable diaper 1>> Fig. 1 is a schematic perspective view of a diaper 1. Fig. 2 is a schematic plan view of the diaper 1 in an unfolded and stretched state, as seen from the wearer's skin side. Fig. 3 is a schematic cross-sectional view taken along line AA in Fig. 2.

[0049] The pants-type diaper 1 has three intersecting directions: a vertical direction, a horizontal direction, and a front-to-rear direction, and has a waist opening BH and a pair of leg openings LH. In the vertical direction, the side of the waist opening BH is the upper side, and the side facing the wearer's crotch is the lower side. In the front-to-rear direction, the side facing the wearer's stomach is the front side, and the side facing the wearer's back is the rear side. The diaper 1 also has a thickness direction in which materials are layered, as shown in Figure 3. The side in contact with the wearer in the thickness direction is the skin side, and the opposite side is the non-skin side.

[0050] The diaper 1 has an absorbent main body 10 and a waist portion 2 in which a ventral waist portion 20 and a dorsal waist portion 30 are joined at both left and right ends by a pair of side joining regions 40. The waist portion 2 is arranged on the non-skin side of the absorbent main body 10 and is joined to the absorbent main body 10 with an adhesive or the like.

[0051] In the diaper 1 of this embodiment, the ventral waist portion 20 and the back waist portion 30 are formed from separate members, and the non-skin side of the absorbent main body 10 is exposed in the crotch region, but this is not limiting. For example, the diaper may have an exterior member formed from three members: the ventral waist portion 20, the back waist portion 30, and the crotch region connecting them, or the diaper may have an exterior member formed from a single member that is continuous from the ventral waist portion 20 to the back waist portion 30.

[0052] As shown in Fig. 3, the absorbent body 10 has an absorbent core 11, a liquid-permeable top sheet 12 arranged closer to the skin than the absorbent core 11, a liquid-impermeable back sheet 13 arranged closer to the skin than the absorbent core 11, and an exterior sheet 14. The absorbent core 11 may be any material that absorbs and retains excreted liquid, and examples thereof include a liquid-absorbent material such as pulp fiber or a superabsorbent polymer molded into a predetermined shape. The absorbent core 11 may be covered with a liquid-permeable sheet such as tissue paper or a nonwoven fabric.

[0053] 2, leg-hole elastic members 15 (e.g., rubber thread) that stretch along the longitudinal direction of the absorbent main body 10 may be provided on both left-right side portions of the absorbent main body 10. Furthermore, leakage preventing walls 16 that can stand up on the skin side may be provided on both left-right side portions of the absorbent main body 10 (inside the leg-hole elastic members 15). This makes it possible to suppress lateral leakage of excreted liquid. The leakage preventing walls 16 are formed, for example, by folding both left-right side portions of the outer sheet 14 inward in the left-right direction so as to be positioned on the skin-facing side of the top sheet 12, and providing leakage preventing wall elastic members 161 (e.g., rubber thread) that stretch in the longitudinal direction at the folded-back portions.

[0054] The ventral waist portion 20 and the back waist portion 30 are rectangular members in a plan view, and each include a skin-side sheet 21, 31, a non-skin-side sheet 22, 32, and a plurality of waist elastic members 23, 33 (e.g., rubber threads) that stretch in the left-right direction. The plurality of waist elastic members 23, 33 are arranged in a line in the vertical direction between the skin-side sheet 21, 31 and the non-skin-side sheet 22, 32.

[0055] Flexible sheet materials are preferred for the skin side sheets 21, 31 and the non-skin side sheets 22, 32, and examples thereof include spunbond nonwoven fabric, meltblown nonwoven fabric, and SMS (spunbond / meltblown / spunbond) nonwoven fabric. The constituent fibers of the nonwoven fabric are not limited to single fibers of polypropylene (PP), a typical example of thermoplastic resin, but may also be single fibers of other thermoplastic resins such as polyethylene (PE), or may further be composite fibers having a sheath-core structure such as PE and PP.

[0056] Furthermore, the skin side sheets 21, 31 and the non-skin side sheets 22, 32 may be composed of two sheets, as in this embodiment, or a single sheet may be folded over and over to form two layers that serve as the skin side sheet and the non-skin side sheet. The waistband portion may have another sheet that overlaps the skin side sheet and the non-skin side sheet, and the welding portion 50 described below may join three or more layers of sheets.

[0057] In the diaper 1, the portion of the outer covering member that overlaps the side joint region 40 in the vertical direction is referred to as the waist portion 2 (the ventral waist portion 20 and the back waist portion 30). The diaper 1 may also have a portion of the outer covering member that extends from the waist portion 2 toward the crotch area (in this embodiment, a portion 3 extending from the back waist portion 30). This allows the buttocks and lower abdomen of the wearer to be covered.

[0058] <<About waist area 2>> Fig. 4A is an explanatory diagram of the side joint region 40 and the welded portion row 50L provided in the waistline portion 2, and Fig. 4B is a schematic enlarged view of part B in Fig. 4A. Figs. 5A and 5B are explanatory diagrams of the attachment function of the waistline elastic member 23 (33).

[0059] The skin side sheet 21 and the non-skin side sheet 22 that make up the ventral waistline portion 20 are intermittently joined together at a plurality of welded portions 50 that are discretely arranged in the vertical and horizontal directions. Similarly, the skin side sheet 31 and the non-skin side sheet 32 ​​that make up the back waistline portion 30 are intermittently joined together at a plurality of welded portions 50 that are discretely arranged in the vertical and horizontal directions.

[0060] The ventral waistline portion 20 and the back waistline portion 30 have almost the same configuration. Therefore, in the following description, the contents common to both the ventral waistline portion 20 and the back waistline portion 30 will be described only for the ventral waistline portion 20 as a representative of both. For the back waistline portion 30, the reference numerals of the components etc. corresponding to those of the ventral waistline portion 20 will be shown in parentheses as necessary.

[0061] 4A and 4B, the ventral waistline portion 20 (30) is provided with a plurality of welded portion rows 50L spaced apart in the left-right direction, in which a plurality of welded portions 50 are arranged at intervals in the up-down direction. While Fig. 4A illustrates an example of a welded portion row 50L that extends in the up-down direction while meandering in a curved, serpentine shape, the shape of the welded portion row 50L is not particularly limited. For example, the welded portion row 50L may be a row that extends straight in the up-down direction, or a linear or curved row that is inclined to one side in the left-right direction.

[0062] As shown in Fig. 4B, the waist elastic members 23 (33) are arranged so as to pass between the welded portions 50 that are lined up in the vertical direction. Therefore, it is advisable to align the vertical positions of the welded portions 50 that are lined up in the left-right direction. By doing so, the vertical positions of the spaces between the vertically adjacent welded portions 50 through which the waist elastic members 23 (33) pass are aligned, so that the waist elastic members 23 (33) can be arranged along the left-right direction.

[0063] In the following description, of the multiple welded portions 50, two welded portions 50 located on both sides of the waist elastic member 23 (33) in the up-down direction will be referred to as a "pair of welded portions 50S." Of the pair of welded portions 50S, the welded portion 50 arranged on the upper side of the waist elastic member 23 (33) will be referred to as an "upper welded portion 50a," and the welded portion 50 arranged on the lower side will be referred to as a "lower welded portion 50b."

[0064] The waist elastic member 23 (33) preferably passes in the left-right direction between pairs of welded parts 50S that are at the same vertical position, but may pass between pairs of welded parts 50S that are offset in the vertical position. In this case as well, the waist portion 20 can be made stretchable in the left-right direction.

[0065] Also, as shown in FIG. 5A, the upper welding part 50a and the lower welding part 50b that form the welding part pair 50S are arranged side by side with a gap G1 in the vertical direction. The size of the gap G1 is set to be the same as or slightly larger than the outer diameter D1 of the circumferential elastic member 23(33) in the state where the circumferential part 20 is maximally extended in the left-right direction (G1≧D1).

[0066] However, the circumferential elastic member 23(33) becomes thicker as it contracts in the left-right direction. Therefore, as shown in FIG. 5B, the gap G1 of the welding part pair 50S is made smaller than the maximum outer shape D2 of the circumferential elastic member 23(33) in the state where the circumferential elastic member 23(33) contracts in the left-right direction (that is, the natural state of the circumferential part 20) (G1<D2). By doing so, the circumferential elastic member 23(33) in the state of contracting in the left-right direction is sandwiched in the vertical direction by the welding part pair 50 (the expansion in the vertical direction is restricted). Therefore, the positions (movements) of the circumferential elastic member 23(33) in the left-right direction and the vertical direction with respect to the skin-side sheet 21(31) and the non-skin-side sheet 22(33) are restricted.

[0067] Therefore, even if the circumferential elastic member 23(33) is not fixed to the skin-side sheet 21(31) and the non-skin-side sheet 22(32) using an adhesive, the displacement of the circumferential elastic member 23(33) can be suppressed, and the elasticity of the circumferential part 2 can be maintained. That is, in the diaper 1 of the present embodiment, by using the welding part 50, the circumferential elastic member 23(33) can be attached to the skin-side sheet 21(31) and the non-skin-side sheet 22(33) without using an adhesive or by reducing the amount of adhesive used. Therefore, it is possible to suppress a decrease in the flexibility of the circumferential part 20 due to the curing of the adhesive. Also, it is possible to suppress a decrease in the elastic characteristics of the circumferential elastic member 23(33) due to the curing of the adhesive.

[0068] <<Regarding suppression of slipping out and cutting of the circumferential elastic members 23, 33>> 6A and 6B are diagrams showing a state in which the end of the waist elastic member 23 (33) is in contact with the side joint portion 41. FIGS. 7A to 7C are diagrams showing a state in which the end of the waist elastic member 23 (33) is sandwiched by the side joint portion 41. FIGS. 8A and 8B are diagrams showing modified examples of the side joint portion region 40.

[0069] The ventral waistline portion 20 and the back waistline portion 30 are joined at both left and right ends in a pair of side joint regions 40. As shown in Figures 4A and 4B, a plurality of side joints 41 are arranged vertically in the side joint region 40. Examples of methods for forming the side joints 41 include welding means such as ultrasonic welding, heat welding, and high-frequency sealing, and non-heating pressure means.

[0070] As shown in FIG. 2 , the waist elastic members 23 (33) are provided in the left-right direction, extending from one side joint region 40 to the other side joint region 40 in the left-right direction. Furthermore, the sheets constituting the waist portion 2 are firmly joined (pressed) together in the side joint region 40 so that the ventral waist portion 20 and the back waist portion 30 do not separate while the diaper 1 is being worn. Therefore, the left-right ends of the waist elastic members 23 (33) are firmly sandwiched and fixed between the skin-side sheet 21 (31) and the non-skin-side sheet 22 (32) in the side joint region 40. Therefore, the waist elastic members 23 (33) do not exhibit stretchability in the side joint region 40, but exhibit stretchability between the pair of side joint regions 40.

[0071] However, in the diaper 1 of this embodiment, the waist elastic members 23(33) are prevented from shifting in position by the pairs of welded portions 50S that sandwich the waist elastic members 23(33) in the vertical direction, and the waist elastic members 23(33) are attached to the sheet without adhesive or with a small amount of adhesive. Therefore, if the waist elastic members 23(33) come loose from the side joint regions 40, there is a risk that the waist elastic members 23(33) will also come loose from between the pairs of welded portions 50S that are aligned in the horizontal direction. In this case, the waist elastic members 23(33) will not be able to impart stretchability to the waist portion 2, and the stretchability of the waist portion 2 will be reduced.

[0072] Therefore, in the diaper 1 of this embodiment, at least one (first elastic member) of the multiple waist elastic members 23 (33) included in the diaper 1 satisfies the following conditions. First, as shown in Fig. 6A etc., among the multiple welded portion pairs 50S, the welded portion pair 50S that is adjacent to the inner side of the side join region 40 on one (or the other) side in the left-right direction and that sandwiches the waist elastic member 23 (33) between them will be referred to as the "first welded portion pair 50S1." Furthermore, the welded portion pair 50S that is adjacent to the inner side of the first welded portion pair 50S1 in the left-right direction and that sandwiches the same waist elastic member 23 (33) between them will be referred to as the "second welded portion pair 50S2."

[0073] When the diaper 1 (waist portion 2) in a stretched state is viewed in the front-to-back direction (thickness direction), the center line Cl2 of the portion of the waist elastic member 23 (33) located in the side joint region 40 on one side (or the other side) in the left-to-right direction is inclined relative to the center line Cl1 of the portion of the same waist elastic member 23 (33) located between the first welded portion pair 50S1 and the second welded portion pair 50S2.

[0074] The center lines Cl1 and Cl2 of the waist elastic member 23(33) are center lines that vertically bisect the waist elastic member 23(33). The portion of the waist elastic member 23(33) located between the first welded portion pair 50S1 and the second welded portion pair 50S2 is the portion of the waist elastic member 23(33) located between the outermost end in the left-right direction of the first welded portion pair 50S1 and the innermost end in the left-right direction of the second welded portion pair 50S2.

[0075] The waist elastic member 23 (33) located between the first welded portion pair 50S1 and the second welded portion pair 50S2 is oriented in the left-right direction and is stretchable in the left-right direction. Therefore, its center line Cl1 is generally aligned in the left-right direction. Meanwhile, in the side joint region 40, the ends of the waist elastic member 23 (33) that were cut during the manufacture of the diaper 1 are sandwiched and fixed between the skin-side sheet 21 (31) and the non-skin-side sheet 22 (32), and are therefore not stretchable. Therefore, its center line Cl2 can be tilted relative to the center line Cl1 (left-right direction).

[0076] Furthermore, the position of the waist elastic member 23 (33) in the side joint region 40 is not restricted by the welded portion pair 50S. Therefore, even when the waist portion 2 is stretched, the center line Cl2 is likely to have a curved shape as shown in Fig. 6A etc. Therefore, if it can be visually confirmed that at least a portion of the center line Cl2 is inclined with respect to the center line Cl1 (left-right direction), the center line Cl2 is inclined with respect to the center line Cl1.

[0077] A more rigorous confirmation method is as follows. First, a magnified image of the waistline portion 2 in a stretched state is taken using a digital microscope or the like. In the taken image data, center points p in the up-down direction of the target waistline elastic member 23 (33) are identified at predetermined intervals in the left-right direction. A line connecting the identified center points p, or a line approximated by the least squares method, is obtained as center lines Cl1 and Cl2', and their slopes are compared.

[0078] The diaper 1 in a stretched state refers to a state in which the elastic members of the diaper 1 are stretched to the extent that wrinkles in the diaper 1 are no longer visible. Specifically, this refers to a state in which each component of the diaper 1 is stretched to the extent that the dimensions of that component are equal to or close to the dimensions of that component alone (i.e., the dimensions when the elastic members are not stretched). The inclinations of the centerlines Cl1 and Cl2 may be checked by undoing the side joint regions 40 and opening the diaper 1 to be flat (FIG. 2), or by checking the inclinations with the ventral waistband 20 and the dorsal waistband 30 connected together.

[0079] The direction (left-right direction) along the center line Cl1 of the waist elastic member 23 (33) located between the first welded portion pair 50S1 and the second welded portion pair 50S2 is the direction in which the contractile force of the waist elastic member 23 (33) acts. That is, this is the direction in which the force that causes the waist elastic member 23 (33) to slip out of the side joint region 40 (so-called rubber slip-out) acts. Therefore, by tilting the center line Cl2 of the waist elastic member 23 (33) in the side joint region 40 with respect to the center line Cl1 (left-right direction), it is possible to prevent the force that causes rubber slip-out from directly acting on the portion of the waist elastic member 23 (33) located in the side joint region 40 (i.e., it is possible to disperse the force that causes rubber slip-out). Therefore, it is possible to prevent the waist elastic member 23 from slipping out of the side joint region 40.

[0080] Furthermore, when the waist elastic members 23 (33) located in the side joint regions 40 are inclined relative to the left-right direction, the length of the waist elastic members 23 (33) located in the side joint regions 40 is longer than when they are aligned in the left-right direction. As described above, in the side joint regions 40, the waist elastic members 23 (33) are tightly sandwiched between the sheets and have a higher frictional force with the sheets than in other regions. Therefore, by increasing the length of the waist elastic members 23 (33) located in the side joint regions 40, the length of the waist elastic members 23 (33) that are subject to a stronger frictional force with the sheets is increased, further preventing the waist elastic members 23 from slipping out of the side joint regions 40.

[0081] Therefore, when the end 2S of the waist portion 2 is located laterally outward of the side joint region 40, it is preferable that the waist elastic member 23 (33) extends laterally outward (to the end 2S) of the side joint region 40 on one side (or the other) of the left-right direction, as shown in Figure 6A, etc.

[0082] By doing so, the waist elastic members 23 (33) are positioned across the entire left-right area of ​​the side joint region 40 where the frictional force with the sheet is strong. Therefore, the length of the waist elastic members 23 (33) where the frictional force with the sheet is strong is increased, which further prevents the waist elastic members 23 (33) from slipping out of the side joint region 40. However, the present invention is not limited to the above, and the waist elastic members 23 (33) may be interrupted midway through the side joint region 40.

[0083] Thus, according to the diaper 1 of this embodiment, the amount of adhesive used to attach the waist elastic member 23 (33) by the welded portion pair 50S is reduced, thereby maintaining the flexibility of the waist portion 2 while preventing the waist elastic member 23 from slipping out, and maintaining the stretchability of the waist portion 2.

[0084] In addition, in order to tilt the waist elastic member 23 (33) in the side joint region 40, for example, as shown in Figure 6A (or Figure 6B), a portion of the waist elastic member 23 (33) may be brought into contact with the side joint 41 in the side joint region 40 on one side (or the other side) in the left-right direction.

[0085] By doing so, the waist elastic members 23 (33) follow the contours of the side joints 41, so that the center lines Cl2 of the waist elastic members 23 (33) located in the side joint regions 40 can be inclined with respect to the center line Cl1 (left-right direction). In this case, frictional force is generated at the contact points between the waist elastic members 23 (33) and the side joints 41, so that slipping out of the waist elastic members 23 (33) from the side joint regions 40 can be further suppressed.

[0086] 7A to 7C, in the side joint region 40 on one (or the other) side in the left-right direction, a portion of the waist elastic member 23 (33) may overlap the side joint 41 in the thickness direction. In other words, a portion of the waist elastic member 23 (33) may be sandwiched between the skin side sheet 21 (31) and the non-skin side sheet 22 (33) by the side joint 41.

[0087] In this case, too, the portions of the waist elastic members 23 (33) that are not sandwiched in the side joints 41 follow the contours of the side joints 41, so the center lines Cl2 of the waist elastic members 23 (33) located in the side joint regions 40 can be inclined with respect to the center line Cl1 (left-right direction). In this case, because a portion of the waist elastic members 23 (33) is tightly sandwiched between the sheets at the side joints 41, slipping out of the side joint regions 40 of the waist elastic members 23 (33) can be further prevented.

[0088] 7A, even if a part of the waist elastic member 23 (33) is torn in the middle in the left-right direction, it is sufficient if the torn end 23c (33c) is fixed at the side joint 41. In this case, too, it is possible to prevent the waist elastic member 23 (33) from slipping out of the side joint region 40.

[0089] Furthermore, when the side joint 41 and a portion of the waist elastic member 23 (33) overlap in the thickness direction (see FIG. 7A), it is preferable to determine the center line Cl2 at the portion of the waist elastic member 23 (33) that does not overlap with the side joint 41. Furthermore, when the waist elastic member 23 (33) branches at the side joint 41 (see FIG. 7C), it is preferable to determine the center line Cl2 at the portion of the waist elastic member 23 (33) with the larger area.

[0090] Furthermore, it is preferable that the waist elastic members 23 (33) are inclined with respect to the center line Cl1 (left-right direction) in the side joint regions 40 on both sides in the left-right direction. This makes it difficult for the waist elastic members 23 (33) to slip out of the side joint regions 40 on both sides in the left-right direction. Therefore, the waist elastic members 23 (33) can impart stretchability to the waist portion 2 across the pair of side joint regions 40.

[0091] Preferably, the waist elastic members 23 partially overlap in the thickness direction with the side joint regions 41 on one side in the left-right direction, and partially contact with the side joint regions 41 on the other side in the left-right direction. Alternatively, the waist elastic members 23 (33) may partially overlap in the thickness direction with the side joint regions 41 on both left-right sides, or may partially contact with the side joint regions 41 on both left-right sides. In these cases, the waist elastic members 23 (33) are less likely to slip out of the side joint regions 40 on both left-right sides.

[0092] It is also preferable that more of the waist elastic members 23 (33) of the diaper 1 are inclined with respect to the center line Cl1 (left-right direction) in the side joint regions 40. This can prevent more of the waist elastic members 23 (33) from slipping out of the side joint regions 40, thereby maintaining the stretchability of the waist portion 2.

[0093] Preferably, in the side joint region 40 on one side in the left-right direction, there are one or more waist elastic members 23 (33) (first elastic members) that partially overlap the side joint 41 in the thickness direction, and there are one or more waist elastic members 23 (33) (second elastic members) that partially contact the side joint 41. This can further prevent the multiple waist elastic members 23 (33) from slipping out of the side joint region 40.

[0094] As shown in FIG. 6A, the vertical distance G2 between the side joints 41 aligned in the left-right direction with the first welded portion pair 50S1 is preferably equal to or greater than the vertical distance G1 between the first welded portion pair 50S1 (G2≧G1).

[0095] The vertical spacing G1 between the first welded portion pair 50S1 is the vertical length from the lower end of the upper welded portion 50a1 to the upper end of the lower welded portion 50b1. Similarly, the vertical spacing G2 between the side joints 41 is the vertical length from the lower end of the upper side joint 41 to the upper end of the lower side joint 41. When the side joints 41 are arranged in a staggered pattern as shown in FIG. 6A, the vertical spacing G2 is the spacing between adjacent side joints 41 in the vertical direction. In addition, although the side joints 41 in this embodiment are arranged at a constant vertical spacing G2, the vertical spacing G2 between the side joints 41 may vary depending on the vertical position. Therefore, the distance G2 between the side joints 41 aligned in the left-right direction with the first welded portion pair 50S1 (i.e., the side joints 41 whose vertical position overlaps with the first welded portion pair 50S1, or the side joints 41 whose vertical position is closest to the first welded portion pair 50S1) is used as the comparison target.

[0096] By relatively widening the vertical spacing G2 between the side joints 41, the number of highly rigid side joints 40 can be reduced. This prevents the side joint region 40 from reducing the flexibility of the waistline portion 2. Furthermore, multiple side joints 41 are not arranged between the first welded portion pairs 50S1, i.e., in the region that vertically overlaps the space through which the waistline elastic members 23 (33) pass. This reduces the probability (area ratio) that the waistline elastic members 23 (33) overlap with the side joints 41 in the thickness direction. Therefore, when forming the side joints 41 by welding or pressure, this prevents the waistline elastic members 23 (33) from being cut by the convex patterns that form the side joints 41 (e.g., convex portions formed on the outer peripheral surfaces of rollers that sandwich the sheet). This prevents the waistline elastic members 23 (33) from slipping out of the side joint region 40.

[0097] However, as shown in a modified example of FIG. 8A, the vertical distance G2 between the side joints 41 aligned in the left-right direction with the first welded portion pair 50S1 may be shorter than the vertical distance G1 between the first welded portion pair 50S1 (G2 <G1)。

[0098] In this case, a plurality of side joints 41 (parts) are likely to be arranged between the first welded portions 50S1, i.e., in the region that overlaps in the vertical direction with the space through which the waist elastic members 23 (33) pass. As a result, a part of the waist elastic members 23 (33) is likely to come into contact with the side joints 41 (see, for example, FIG. 6A ), or a part of the waist elastic members 23 (33) is likely to overlap with the side joints 41 in the thickness direction (see, for example, FIG. 7A ). This further prevents the waist elastic members 23 (33) from slipping out of the side joint regions 40.

[0099] Furthermore, as shown in FIG. 4B, in the side joint region 40, when a plurality of side joints 41 are arranged in a row 41L in the vertical direction and a plurality of side joints 41 are arranged in the horizontal direction, it is preferable that the rows 41L of the side joints 41 are spaced apart in the horizontal direction.

[0100] By doing so, it is possible to lengthen the length in the left-right direction of the side joint region 40 where the frictional force between the sheet and the waist elastic member 23 (33) is increased. Therefore, the length of the waist elastic member 23 (33) where the frictional force with the sheet is strong is increased, and it is possible to further suppress the slipping out of the waist elastic member 23 (33) from the side joint region 40. In addition, the density (number / mm 2 ) can be reduced, and the flexibility of the waist portion 2 can be maintained.

[0101] 4B, the side joint portions 41 are arranged in a staggered pattern (i.e., the side joint portions 41 in each of two horizontally adjacent side joint portion rows 41L are offset in the vertical direction). However, this is not limiting, and the vertical positions of the horizontally adjacent side joint portions 41 may be aligned. Furthermore, the number of side joint portion rows 41L may be one row, or three or more rows.

[0102] Furthermore, when the side joints 41 are arranged in a staggered pattern (FIG. 8A), it is preferable that the vertical distance G2 between the side joints 41 aligned in the left-right direction with the first welded pair 50S1 (i.e., the vertical distance G2 between the side joint 41 adjacent to the first welded pair 50S1 in the left-right direction and the side joint 41 adjacent to the first welded pair 50S1 but vertically shifted from the side joint 41) is smaller than the diameter of the waist elastic member 23 (33) in its left-right contracted state (i.e., the width of the waist elastic member 23 in the up-down direction of the diaper 1). Note that the diameter of the waist elastic member 23 (33) in its left-right contracted state refers to the diameter of the waist elastic member 23 (33) in its natural state when separated from the diaper 1, i.e., the maximum diameter D2 of the waist elastic member 23 (33) of the diaper 1 in its natural state, as shown in FIG. 5B.

[0103] As a result, when the waist elastic members 23 (33) cut during the manufacture of the diaper 1 are fixed at the side joint regions 41 while shrinking, they are sandwiched vertically between the side joint regions 41, which have a diameter smaller than that of the cut waist elastic members 23. As a result, the waist elastic members 23 come into contact with at least one of the side joint regions 41 that are aligned laterally and offset vertically, and are likely to bend along the contour of the side joint regions 41. As a result, the center line Cl2 of the waist elastic members 23 (33) located in the side joint regions 40 is inclined relative to the center line Cl (lateral direction), which further prevents the waist elastic members 23 from slipping out of the side joint regions 40.

[0104] 8B, a welded portion 50 joining the skin side sheet 21 (22) and the non-skin side sheet 22 (32) may also be formed in the side joint region 40. In this case, the side joint region 40 preferably has a portion where the welded portion 50 and the side joint region 41 overlap in the thickness direction of the waistband portion 2.

[0105] This makes it easier to form the side joints 41 so as to overlap in the thickness direction with the waist elastic members 23 passing between the welded portion pairs 50S. Therefore, it becomes easier for parts of the waist elastic members 23 (33) to come into contact with the side joints 41 (see FIG. 6A, etc.) or for parts of the waist elastic members 23 (33) to overlap in the thickness direction with the side joints 41 (see FIG. 7A, etc.). This makes it possible to further prevent the waist elastic members 23 (33) from slipping out of the side joint regions 40.

[0106] In addition, in at least one of the pair of side joint regions 40, as shown in FIG. 6A, it is preferable that at least one waist elastic member 23 of the ventral waist portion 20 is arranged so as to be vertically offset from the waist elastic member 33 of the back waist portion 30.

[0107] This prevents both the ventral-side waist elastic member 23 and the dorsal-side waist elastic member 33 from being cut by the convex pattern forming the side joint 41 when the side joint 41 is formed by welding or pressure. Therefore, the number of waist elastic members 23 (33) cut by the convex pattern forming the side joint 41 can be reduced, and the stretchability of the waist portion 2 can be maintained.

[0108] Furthermore, by vertically shifting the ventral waist elastic member 23 and the dorsal waist elastic member 33, the number of overlapping materials in the thickness direction at the portion forming the side joint 41 is reduced. This allows the skin side sheets 21, 31 and the non-skin side sheets 22, 32 to be firmly joined (pressed together). Increasing the joining strength of the side joint 41 also increases the friction between the sheet and the waist elastic member 23 (33) located in the side joint region 40, further preventing the waist elastic member 23 (33) from slipping out of the side joint region 40.

[0109] 9 is an explanatory diagram of the vertical length L1 of the side joint portion 41. Here, the extension ratio of the waist elastic member 23 when the diaper 1 is stretched to its maximum in the left-right direction is defined as a, and the width of the waist elastic member 23 in the vertical direction of the diaper 1 at this time is defined as D mm (= D1 in FIG. 5A). Meanwhile, the maximum extension ratio of a single waist elastic member 23 (33) separated from the diaper 1, i.e., the extension ratio immediately before the single waist elastic member 23 (33) breaks, is defined as b. The extension ratio is defined as the length of the waist elastic member 23 (33) in the stretched state divided by the length of the waist elastic member 23 (33) in its natural (unloaded) state.

[0110] The waist elastic member 23 (33) is also considered to be stretchable in its width direction (vertical direction of the diaper 1) to the same stretch ratio as in its longitudinal direction (left-right direction of the diaper 1). Therefore, when the waist elastic member 23 (33) is placed in the diaper 1, that is, when the waist elastic member 23 (33) has a stretch ratio of a in the longitudinal direction (left-right direction) and a width (vertical length) of D mm, it is considered to be stretchable in the width direction (vertical direction) to b times. In this case, the width (vertical length) of the waist elastic member 23 (33) is considered to be "D × b / a (mm)."

[0111] Therefore, the vertical length L1 of the side joint 41 aligned in the left-right direction with the first welded portion pair 50S1 is set to be equal to or less than "D × b / a (mm)." For example, if the extension ratio a of the waist elastic member 23 at maximum extension of the diaper 1 is 2.5, the width D mm is 0.2 mm, and the maximum extension ratio b of a single waist elastic member 23 is 8, then the vertical length L1 of the side joint 41 should be set to be equal to or less than 0.6 mm (= 0.2 × 8 / 2.5).

[0112] By doing so, even if the side joints 41 are formed so as to overlap the waist elastic members 23 (33), the vertical length L1 of the side joints 41 is longer than the vertical length L1 of the side joints 41, increasing the probability that the waist elastic members 23 (33) can be stretched in the vertical direction without breaking. Therefore, the convex pattern forming the side joints 41 can prevent the waist elastic members 23 (33) from being stepped on and broken. Therefore, it is possible to prevent the waist elastic members 23 (33) from slipping out of the side joint regions 40.

[0113] When the cross section of the waist elastic member 23 (33) is circular, the width D mm of the waist elastic member 23 in the vertical direction of the diaper 1 corresponds to the diameter of the waist elastic member 23 (33). However, the waist elastic member 23 (33) may be a waist elastic member 23 (33) having a cross section other than a circle (e.g., an oval), or a waist elastic member 23 (33) having a flat cross section, i.e., a so-called flat elastic.

[0114] The extension ratios a and b and the width D mm can be measured by known methods. For example, the left-right length W0 of the ventral waist portion 20 (30) in the natural state of the diaper 1 is measured, and the left-right length W1 of the ventral waist portion 20 (30) when it is stretched to its maximum length in the natural state is measured. The value (W1 / W0) obtained by dividing the stretched length W1 by the natural length W0 may be multiplied by a. Furthermore, with the ventral waist portion 20 (30) stretched to its maximum in the left-right direction, the vertical width D mm of the waist elastic member 23 (33) may be measured through the sheet constituting the ventral waist portion 20 (30). Alternatively, the waist elastic member 23 (33) may be removed from the ventral waist portion 20 (30) and stretched a-fold, and the width D mm in the direction corresponding to the vertical direction of the diaper 1 may be measured. Furthermore, the waist elastic member 23 (33) removed from the ventral waist portion 20 (30) is set between the chucks of a tensile tester and stretched in the direction of extension of the waist elastic member 23 (33), and the load at which the waist elastic member 23 (33) breaks is obtained. The length L0 of another waist elastic member 23 (33) removed from the ventral waist portion 20 (30) in its natural state is measured. Thereafter, the waist elastic member 23 (33) is set in the tensile tester and stretched to a load slightly smaller than the load at break, and the length L1 of the waist elastic member 23 (33) is obtained based on the distance between the chucks at that time. The length L1 divided by the length L0 in its natural state (L1 / L0) is then multiplied by b.

[0115] Although the side joints 41 of this embodiment are illustrated as a rectangle with rounded corners as shown in FIG. 4B, the shape of the side joints 41 is not particularly limited. However, as shown in FIG. 4B, the side joints 41 preferably have a curved portion at least in part of their periphery. Examples of other shapes with a curved portion include a circle, an ellipse, and a shape with an irregular contour. In this case, the waist elastic members 23 (33) tend to follow the contour (curved portion) of the side joints 41, and the center line Cl2 of the waist elastic members 23 (33) located in the side joint region 40 tends to tilt relative to the center line Cl1 (in the left-right direction) of the waist elastic members 23 located between the first welded portion pair 50S1 and the second welded portion pair 50S2. This further reduces slippage of the waist elastic members 23 (33) from the side joint region 40. It should be noted that the shapes of all the side joints 41 arranged in the side joint region 40 do not necessarily have to be the same, and for example, the shapes of the side joints 41 may differ depending on their positions in the up-down direction.

[0116] 10A and 10B are diagrams showing modified examples of the welded portion 50. While Fig. 4B illustrates the welded portion 50 as a parallelogram, the shape of the welded portion 50 is not particularly limited. For example, as shown in Fig. 10A, the welded portion 50 may have a shape in which the vertical distance between the two welded portions 50 constituting the welded portion pair 50S is wider at at least one of the left-right end portions (both ends G3 in Fig. 10A) than at the left-right center portion (G1) of the welded portion pair 50S.

[0117] In this case, the waist elastic members 23 extend in the left-right direction through the gaps between the pairs of welded portions 50S aligned in the left-right direction, and can move up and down in the portions of the left-right ends of the welded portions 50 where the gap (G3) is wide. In other words, the waist elastic members 23 can tilt slightly in the left-right direction along the left-right ends of the welded portions 50. Therefore, the waist elastic members 23 (33) are less likely to slip out of the pairs of welded portions 50S, and the stretchability of the waist portion 2 is maintained.

[0118] 10A, when the distance G3 between the lateral ends of the welded portion pair 50S is wide, the waist elastic member 23 (33) is more likely to fit between the raised patterns (e.g., raised portions formed on the outer peripheral surfaces of the rollers that sandwich the sheet) that form the welded portion pair 50S during the manufacture of the diaper 1. This prevents the waist elastic member 23 (33) from being cut by the raised patterns that form the welded portion pair 50S during the formation of the welded portion 50.

[0119] The welded portion 50 may have a curved portion at a portion of its periphery. For example, it may be a rectangle with rounded corners as shown in FIG. 10B, a circle, an ellipse, or a shape with an uneven contour. In this case, the waist elastic member 23 can extend in the left-right direction between the pairs of welded portions 50S aligned in the left-right direction, while being slightly inclined in the left-right direction along the curved portion of the welded portion 50. This makes it difficult for the waist elastic member 23 (33) to slip out of the pairs of welded portions 50S, maintaining the stretchability of the waist portion 2.

[0120] FIG. 11 is an enlarged cross-sectional view of the waist elastic member 23 (33). Examples of the waist elastic member 23 (33) include polyurethane, polyester, and latex (natural rubber). Among these, as shown in FIG. 11, a thread-like elastic member consisting of a plurality of elastic fibers 4 (elastic threads) such as polyurethane or polyester is preferred. In this case, the outer shape of the waist elastic member 23 (33) is uneven, which increases the surface area of ​​the waist elastic member 23 (33) that comes into contact with the constituent fibers of the sheet and increases the frictional force with the sheet. Therefore, slipping of the waist elastic member 23 (33) from the side joint region 40 or between the welded portion pairs 50S can be further suppressed.

[0121] Furthermore, since the waist elastic members 23 (33) are made up of a plurality of elastic fibers 4, the waist elastic members 23 (33) are less likely to be cut when the side joints 41 are formed by welding or pressure, and this prevents the waist elastic members 23 (33) from slipping out of the side joint regions 40. More preferably, voids S are formed between the elastic fibers 4. This makes it more difficult for the waist elastic members 23 (33) to be cut, even if they are compressed by the convex patterns forming the side joints 41, because the voids S are compressed to provide clearance for the waist elastic members 23 (33). Furthermore, this prevents the waist elastic members 23 (33) from being displaced in the vertical direction of the diaper 1 when the voids S are compressed, which can prevent the waist elastic members 23 (33) from being cut by the convex patterns.

[0122] It is also preferable that the oil 5 is applied to at least a portion of the surface of the waist elastic member 23 (33). By doing so, even if the protruding pattern forming the side joint 41 accidentally steps on the waist elastic member 23 (33) when forming the side joint 41, the oil makes the waist elastic member 23 (22) slippery, so that the waist elastic member 23 (33) is easily pushed out of the protruding pattern. This prevents the waist elastic member 23 (33) from being cut.

[0123] Furthermore, the weight ratio of the oil (the weight of the oil divided by the weight of the waist elastic members 23 (33)) is preferably 0.5% or more and 5% or less. By setting the weight ratio of the oil to 0.5% or more, the waist elastic members 23 (33) become more slippery, making it easier for the waist elastic members 23 (33) to be pushed out of the convex pattern that forms the side joint region 41. On the other hand, by keeping the weight ratio of the oil to 5% or less, it is possible to prevent the friction between the sheet and the waist elastic members 23 (33) from decreasing too much, and to prevent the waist elastic members 23 from slipping out of the side joint region 40.

[0124] The type of oil is not particularly limited, and may be applied to the elastic fibers 4 constituting the waist elastic member 23 (33) for the purpose of preventing adhesion, improving processability, etc. Specifically, oils whose main components are dimethylpolysiloxane, modified polysiloxane in which some of the methyl groups are substituted with other alkyl groups, phenyl groups, amino groups, etc., mineral oil, etc., can be used.

[0125] Furthermore, an oil may be applied not only to the waist elastic members 23 (33) but also to at least a portion of the surface of the sheet facing the waist elastic members 23 (33). That is, an oil may be applied to the non-skin side of the skin side sheet 21 (31) or the skin side of the non-skin side sheet 22 (32). In this case, too, the waist elastic members 23 (33) become more easily slippery relative to the sheet, and are more likely to be pushed out of the convex pattern that forms the side joint 41. This prevents the waist elastic members 23 (33) from breaking.

[0126] ===Method for manufacturing pants-type disposable diaper 1=== The following describes a method for manufacturing the diaper 1. Fig. 12 is a diagram illustrating the process of manufacturing the diaper 1 on a production line. Fig. 13A is an explanatory diagram illustrating the position where the side joint portion 41 is formed, and Fig. 13B is a schematic side view of the ultrasonic welding device 60 as viewed from the CD direction.

[0127] In the diaper 1 manufacturing line shown in Figure 12, materials are transported in a transport direction corresponding to the left-right direction of the diaper 1. The direction that corresponds to the up-down direction of the diaper 1 and intersects the transport direction is referred to as the CD direction (cross direction). Because the materials for the diaper 1 are continuously transported in the transport direction, Figure 12 shows a virtual cutting position PC for each product pitch P1.

[0128] First, a process for forming the continuum 20a of the ventral waistline portion and the continuum 30a of the back waistline portion is carried out. Specifically, continuum 22a, 32a of the non-skin side sheet is conveyed in the conveyance direction using a conveyance device (not shown) such as a conveyance roller, and continuum 23a, 33a of multiple waistline elastic members stretched in the conveyance direction and continuum 21a, 31a of the skin side sheet join together.

[0129] The plurality of waist elastic member continuums 23a, 33a join together while being spaced apart in the CD direction. The waist elastic member continuums 23a, 33a join together while being stretched to the same value as the maximum elongation ratio of the waist elastic members 23, 33 in the diaper 1. This forms a waist-side continuous laminate 2a in which the plurality of waist elastic member continuums 23a, 33a are arranged between the skin-side sheet continuums 21a, 31a and the non-skin-side sheet continuums 22a, 32a. The material forming the ventral waist portion 20 and the material forming the back waist portion 30 are conveyed while being spaced apart in the CD direction.

[0130] Next, a plurality of welds 50 are formed on the continuous waistband laminate 2a being conveyed in the conveying direction, joining the continuous skin-side sheets 21a, 31a and the continuous non-skin-side sheets 22a, 32a. Although not shown, when forming the welds 50 by ultrasonic welding, this can be done using an ultrasonic welding device (not shown) equipped with an anvil roller that rotates along the conveying direction around its axis in the CD while wrapping the continuous waistband laminate 2a, and a horn that vibrates in a direction perpendicular to the outer circumferential surface of the anvil roller. A raised pattern (raised portions) corresponding to the welds 50 is formed on the outer circumferential surface of the anvil roller and receives the vibrations of the horn.

[0131] 4B and other figures, the pattern of the welded portions 50 is such that rows of welded portions 50L are spaced apart in the CD direction and spaced apart in the conveying direction. Furthermore, welded portions 50 are formed on both sides of the stretched waist elastic member continuum 23a, 33a in the CD direction. Thus, when the waist elastic members 23, 33 of the diaper 1 contract in the left-right direction, a plurality of pairs of welded portions 50S are formed, sandwiching the waist elastic members 23, 33 therebetween.

[0132] 6A, the pattern of the welded portions 50 may be formed intermittently at a product pitch P1 so that the welded portions 50 are not formed at the formation positions of the side joint regions 40. Alternatively, as shown in FIG. 8B, the welded portions 50 may be formed continuously so that the welded portions 50 are also formed at the formation positions of the side joint regions 40.

[0133] In this way, a continuum 20a for the ventral waistline portion and a continuum 30a for the back waistline portion are formed. Next, a process of arranging the absorbent main bodies 10 is carried out. The absorbent main bodies 10 are arranged intermittently in the conveying direction at product pitches P1, with their longitudinal directions oriented along the CD direction. The absorbent main bodies 10 are also bridged and fixed between the continuum 20a for the ventral waistline portion and the continuum 30a for the back waistline portion.

[0134] Next, using a folding device (such as a guide roller or guide plate) not shown, the absorbent main body 10 is folded in half at approximately the center CL in the CD direction, and the continuous body 20a of the ventral waist portion and the continuous body 30a of the dorsal waist portion are overlapped in their thickness direction (front-to-back direction).

[0135] Then, before forming the side joint region 40, the stretched state of the waist elastic member continuum 23a, 33a is relaxed. For example, the stretched state of the waist elastic member continuum 23a, 33a is relaxed until the length of the waist elastic member continuum 23a, 33a is reduced to 50% to 70% of the length of the state in which the waist elastic member continuum 23, 33 is stretched at the maximum stretch ratio of the waist elastic members 23, 33 in the diaper 1. However, the ventral waist portion continuum 20a and the dorsal waist portion continuum 30a are stretched to an appropriate extent compared to their natural state (unloaded state).

[0136] This makes it easier to position the materials, allowing the formation of the side joint region 40 and cutting into individual products to be performed at accurate positions. Furthermore, the side joint region 41 can be formed with a high basis weight of the sheets (fibers) constituting the ventral waistline portion continuum 20a and the dorsal waistline portion continuum 30a. This increases the amount of fiber to be welded (pressurized), thereby enhancing the joining strength of the side joint region 41.

[0137] Then, a plurality of side joints 41 that join the continuous body 20a of the ventral waistline portion and the continuous body 30a of the dorsal waistline portion, which are stacked in the thickness direction (front-to-back direction), are formed in a line in the CD direction to form the side joint region 40.

[0138] 13B, when forming side joints 41 by ultrasonic welding, ultrasonic welding can be performed using an ultrasonic welding device 60 that includes an anvil roller 62 that rotates along the conveyance direction with its axis in the CD direction while wrapping the material around it, and a horn 61 that vibrates in a direction perpendicular to the outer circumferential surface of anvil roller 62. The outer circumferential surface of anvil roller 62 is provided with a convex pattern (convex portions 621) that receives the vibrations of horn 61 and corresponds to side joints 41.

[0139] A pair of side joint regions 40 are formed on either side of the cutting position PC in the conveying direction, and the pair of side joint regions 40 are formed at a product pitch P1. For example, one side joint region 40 becomes the side joint region 40 on one side in the left-right direction of a certain diaper 1, and the other side joint region 40 becomes the side joint region 40 on the other side in the left-right direction of another diaper 1.

[0140] Finally, while the stretch of the waist elastic member continuum 23a, 33a is relaxed, the ventral waist portion continuum 20a and the dorsal waist portion continuum 30a are cut at cutting positions PC at product pitch P1 to form individual diapers 1.

[0141] In the manufacturing method of the diaper 1 of this embodiment, in the step of forming the side joint region 40, when the material is viewed in the front-to-back direction (thickness direction) as shown in Figure 13A, the side joint region 41 is formed so that the center line Cl4 of the side joint region 41 is offset from the center line Cl3 of the welded portion pair 50S (for example, the first welded portion pair 50S1 shown in Figure 6A, etc.) adjacent to the side joint region 40 in the conveying direction (left-right direction).

[0142] The center line Cl3 of the welded portion pair 50S is a line that divides the space between two adjacent welded portions 50 in the CD direction in half. The center line Cl4 of each side joint 41 is a line that divides each side joint 41 in half in the CD direction.

[0143] By shifting the centerlines Cl3 and Cl4 in the CD direction in this manner, it is possible to reduce the probability (area ratio) that the waist elastic members 23 and 33 passing between the pair of welded portions 50S overlap with the protrusions 621 that form the side joints 41. This reduces the possibility that the continuum of waist elastic members 23a and 33a will be cut by the protrusions 621 that form the side joints 41. As a result, it is possible to manufacture a diaper 1 that maintains the stretchability of the waist portion 2.

[0144] In the manufacturing method of the diaper 1 of this embodiment, in the step of forming the side joint region 40, the side joint region 41 is formed while displacing the CD position of the waist elastic member continuum 23a, 33a, which is stretched in the conveying direction. In other words, the protrusions 621 forming the side joint region 41 push out the waist elastic member continuum 23a, 33a without stepping on it. This prevents the waist elastic member continuum 23a, 33a from being cut, and allows the manufacture of a diaper 1 in which the stretchability of the waist region 2 is maintained.

[0145] In order to displace the positions of the waist elastic member continua 23a, 33a in the CD direction, it is preferable to form the side joints 41 by ultrasonic welding, for example. This makes it easier for the waist elastic member continua 23a, 33a to move due to the ultrasonic vibrations of the horn 61, and to be pushed out from the protrusions 621 that form the side joints 41. This prevents the waist elastic member continua 23a, 33a from being cut when the side joints 41 are formed.

[0146] However, the side bond 41 may be formed by a welding method other than ultrasonic welding (for example, heat welding), or by a non-heating pressure method. In the case of heat welding, the fibers around the side bond 41 are also easily melted by the heat, but in the case of ultrasonic welding, the fibers in the side bond 41 mainly melt, and the surrounding fibers do not melt easily. Therefore, it is advisable to confirm that the side bond 41 has been formed by ultrasonic welding by observing the melted state of the fibers around the side bond 41.

[0147] Alternatively, as described above, an oil may be applied to the surface of the waist elastic member continuum 23a, 33a or to the surface of the sheet facing the waist elastic member continuum 23a, 33a. In this case, the waist elastic member continuum 23a, 33a becomes more easily movable and is more easily pushed out of the protrusions 621 that form the side joint portions 41 (their position in the CD direction becomes more easily displaced).

[0148] It is also advisable to cut the waist elastic member continuum 23a, 33a to the product size in a relaxed state. This reduces the contractile force of the waist elastic members 23, 33 immediately after cutting compared to cutting the waist elastic member continuum 23a, 33a in a stretched state. This prevents the waist elastic members 23, 33 from slipping out of the side joint region 40 or the welded portion pair 50S.

[0149] ===Other embodiments=== The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof. [Explanation of symbols]

[0150] 1 Diapers (pants-type absorbent articles), 2 waistband, 10 absorbent body, 11 absorbent core, 12 top sheet, 13 back sheet, 14 exterior sheet, 15 leg-around elastic member, 16 Leakage prevention wall section, 20 abdominal waist portion, 21 skin-side sheet, 22 non-skin-side sheet, 23 Waist elastic member (elastic member) 30 back waist portion, 31 skin-side sheet, 32 non-skin-side sheet, 33 Waist elastic member (elastic member) 40 side joint area, 41 side joint, 50 welded part, 50S welded part pair, 60 ultrasonic welding device, 61 horn, 62 anvil roller, 621 Convex

Claims

1. having vertical, horizontal, and front-to-rear directions that intersect with one another, an absorbent body; a waist portion in which the ventral waist portion and the back waist portion are joined at both ends in the left-right direction by a pair of side joining regions, In the waistband portion, a plurality of elastic members that stretch in the left-right direction are arranged side by side in the up-down direction between the skin side sheet and the non-skin side sheet that are joined by a plurality of welding portions, the plurality of welded portions are located on both sides of the elastic member in the up-down direction, sandwich the elastic member in a state contracted in the left-right direction, and include a plurality of pairs of welded portions that regulate the left-right position of the elastic member relative to the skin side sheet and the non-skin side sheet; The plurality of weld pairs are a first welded portion pair that is adjacent to the inner side of the side joint region on one side in the left-right direction and that sandwiches a first elastic member among the plurality of elastic members; a second pair of welded portions adjacent to the first pair of welded portions on the inner side in the left-right direction and sandwiching the first elastic member therebetween, When the pants-type absorbent article in a stretched state is viewed in the front-rear direction, a center line of a portion of the first elastic member located in the side joint region on one side in the left-right direction is inclined with respect to a center line of a portion of the first elastic member located between the first pair of welded portions and the second pair of welded portions, In the side joint region, a plurality of side joints are arranged side by side in the up-down direction, A pants-type absorbent article, characterized in that, when viewed in the front-rear direction, a part of the first elastic member overlaps with the side joining portion.

2. The pants-type absorbent article according to claim 1, The pants-type absorbent article is characterized in that the first elastic member extends outward in the left-right direction beyond the side joint region on one side in the left-right direction.

3. The pants-type absorbent article according to claim 1 or 2, A pants-type absorbent article, characterized in that a part of the first elastic member is in contact with the side joint portion in the side joint portion region on one side in the left-right direction.

4. The pants-type absorbent article according to claim 1 or 2, A pants-type absorbent article characterized in that in the side joint region on one side of the left-right direction, a portion of the first elastic member is sandwiched between the skin-side sheet and the non-skin-side sheet by the side joint.

5. The pants-type absorbent article according to claim 4, A pants-type absorbent article characterized in that, in the side joint region on one side in the left-right direction, a portion of a second elastic member among the plurality of elastic members is in contact with the side joint.

6. The pants-type absorbent article according to claim 4, A pants-type absorbent article, characterized in that a part of the first elastic member is in contact with the side joint portion in the side joint portion region on the other side in the left-right direction.

7. The pants-type absorbent article according to any one of claims 1 to 6, A pants-type absorbent article, characterized in that the vertical distance between the first pair of welded portions and the side joint portions aligned in the left-right direction is shorter than the vertical distance between the first pair of welded portions.

8. The pants-type absorbent article according to any one of claims 1 to 6, A pants-type absorbent article characterized in that the vertical distance between the first pair of welded portions and the side joint portions aligned in the left-right direction is equal to or greater than the vertical distance between the first pair of welded portions.

9. The pants-type absorbent article according to any one of claims 1 to 8, In the side joint region, a plurality of rows of side joints, each row including a plurality of side joints arranged in the up-down direction, are arranged in the left-right direction, A pants-type absorbent article, wherein the rows of the side joint portions are spaced apart in the left-right direction.

10. A pants-type absorbent article according to any one of claims 1 to 6, In the side joint region, a plurality of rows of side joints, each row including a plurality of side joints arranged in the up-down direction, are arranged in the left-right direction, the side joint portions of each of two rows of side joint portions adjacent to each other in the left-right direction are offset from each other in the up-down direction, A pants-type absorbent article characterized in that the length in the vertical direction between the side joint portion adjacent to the first welded pair in the left-right direction and the side joint portion adjacent to the side joint portion in the left-right direction but shifted in the vertical direction from the side joint portion is smaller than the diameter of the first elastic member when contracted in the left-right direction.

11. The pants-type absorbent article according to any one of claims 1 to 10, The side joint region has a portion where the welded portion and the side joint overlap in the thickness direction of the waist portion.

12. The pants-type absorbent article according to any one of claims 1 to 11, A pants-type absorbent article characterized in that in at least one of the pair of side joint regions, at least one of the elastic members of the ventral waist portion is arranged offset in the vertical direction from the elastic member of the dorsal waist portion.

13. The pants-type absorbent article according to any one of claims 1 to 12, When the pants-type absorbent article is stretched to the maximum in the left-right direction, the stretch ratio of the first elastic member is a times, and the width of the first elastic member in the up-down direction is D mm; When the maximum elongation ratio of the first elastic member alone is b times, The length in the up-down direction of the side joint portion that is aligned with the first welded portion pair in the left-right direction is A pants-type absorbent article characterized in that the thickness is D×b / a mm or less.

14. The pants-type absorbent article according to any one of claims 1 to 13, A pants-type absorbent article characterized in that the vertical distance between the two welded portions that constitute the welded portion pair is wider at the end portion on at least one side in the left-right direction than at the center portion in the left-right direction of the welded portion pair.

15. The pants-type absorbent article according to any one of claims 1 to 14, A pants-type absorbent article, characterized in that an oil is applied to at least a part of the surface of the elastic member.

16. The pants-type absorbent article according to any one of claims 1 to 15, The pants-type absorbent article is characterized in that the elastic member is a thread-like elastic member formed by assembling a plurality of elastic fibers.

Images