Pants-type absorbent article

Abstract

A pants-type absorbent article (1) having an absorbent main body (10) and a waist-encircling member (20) that is stretchable in the left-right direction, the waist-encircling member (20) having a front waist-encircling section (FA) and a rear waist-encircling section (BA), the front waist-encircling section (FA) and the rear waist-encircling section (BA) being joined to each other by a pair of side joining sections (40) provided on both side sections in the left-right direction, the pair of side joining sections (40) being provided between the front waist-encircling section (FA) and the rear waist-encircling section (BA) in the left-right direction, and the pair of side joining sections (40) being provided between the front waist-encircling section (FA) and the rear waist-encircling section (BA) in the left-right direction. The difference between the magnitude of the force when the length of the waist-encircling member (20) is extended from the natural state to 80% of the length at the most extended state and the magnitude of the force when the length of the waist-encircling member (20) is contracted from the most extended state to 80% of the length at the most extended state is 4.0 N or less.

Description

Technical Field

[0001] The present invention relates to a pant-type absorbent article. Background Art

[0002] Conventionally, there is known a shorts-type absorbent article in which a plurality of elastic members having stretchability in the left-right direction are provided in a waist member. For example, Patent Document 1 discloses a shorts-type diaper in which a hot-melt adhesive is applied to the outer surface of an elastic member 12C sandwiched between an outer layer 12S and an inner layer 12H constituting an outer sheet 12 (corresponding to the waist member), and the two layers 12S and 12H are bonded together via the adhesive and the elastic member 12C.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-61348 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In such a pants-type absorbent article, the length of the waist member in the left-right direction (i.e., the circumference of the waist opening) is not always kept constant when worn, and the waist member may expand and contract in the left-right direction according to the body movement and breathing of the wearer. In particular, when the waist member is worn in a highly stretched state of about 80% of the most stretched state in the left-right direction, the tightening force on the wearer's body increases with the expansion and contraction of the waist member, making it difficult to wear the article loosely.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a pants-type absorbent article that can be worn loosely even when the elongation rate of the waist member is high.

[0009] Means for solving problems

[0010] The main technical solution for achieving the above-mentioned purpose is a shorts-type absorbent article, which has mutually intersecting up and down directions, left and right directions, and front and back directions, and has a liquid-absorbing absorbent main body and a waist member with stretchability along the left and right directions, the waist member has a front waist portion arranged at the front side of the front and back directions and a rear waist portion arranged at the rear side of the front and back directions, the front waist portion and the rear waist portion are joined to each other by a pair of side joints arranged on both side portions in the left and right directions, and is characterized in that, in the left and right directions, the difference between the magnitude of the force when the length of the waist member is stretched from a natural state to 80% of the length when it is most stretched and the magnitude of the force when the length of the waist member is contracted from the most stretched state to 80% of the length when it is most stretched is less than 4.0N.

[0011] Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0012] Effects of the Invention

[0013] According to the present invention, a pants-type absorbent article that can be worn loosely even when the waist member has a high elongation rate can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic perspective view showing a structural example of the diaper 1.

[0015] Figure 2 This is a schematic plan view of the diaper 1 in the unfolded and stretched state as viewed from the skin side in the thickness direction.

[0016] Figure 3 yes Figure 2 Schematic diagram of the AA section.

[0017] Figure 4 It is a top view and a cross-sectional view of the absorbent body 10.

[0018] Figure 5 This is a diagram for explaining a range in which a plurality of welded portions 50 are formed in the waist member 20 .

[0019] Figure 6 It is a diagram for explaining an example of the arrangement of the welded portion 50 .

[0020] Fig. 7A and Figure 7B This is a diagram for explaining the principle of attaching the waist elastic member 25 to the waist member 20 using the welded portion 50 .

[0021] FIG. 8 is a diagram for explaining the concept of a tensile test for measuring the magnitude of the tightening force of the waist member 20 .

[0022] Fig. 9 This is a table showing the results of the tensile test on Diaper 1 and Comparative Examples A to F.

[0023] Fig.10 This is a graph showing the relationship between the elongation rate of the waist member and the magnitude of the force during extension and contraction for the diaper 1 and comparative examples A and B.

[0024] Fig.11 This is a table showing the results of the tensile test on the lower side portion FA2 of the diaper 1 and Comparative Examples A to F.

[0025] Fig.12 This is a graph showing the relationship between the elongation rate of the lower side portion FA2 of the waist member and the magnitude of the force during extension and contraction for the diaper 1 and comparative examples A and B.

[0026] Fig.13 This is a table showing the results of the tensile test on the upper side portion FA1 of the diaper 1 and Comparative Examples A to F.

[0027] Fig.14 This is a graph showing the relationship between the elongation rate of the upper side portion FA1 of the waist member and the magnitude of the force during extension and contraction for the diaper 1 and comparative examples A and B. DETAILED DESCRIPTION

[0028] At least the following matters will become clear from the description of this specification and the accompanying drawings.

[0029] (Form 1)

[0030] A shorts-type absorbent article, the shorts-type absorbent article having mutually intersecting up-down directions, left-right directions and front-back directions, and having a liquid-absorbing absorbent main body and a waist member having stretchability along the left-right directions, the waist member having a front waist portion arranged at the front side of the front-back direction and a rear waist portion arranged at the rear side of the front-back direction, the front waist portion and the rear waist portion being joined to each other by a pair of side joints arranged at both side portions in the left-right directions, characterized in that, in the left-right directions, the difference between the magnitude of the force when the length of the waist member is stretched from a natural state to 80% of the length when it is most stretched and the magnitude of the force when the length of the waist member is contracted from the most stretched state to 80% of the length when it is most stretched is less than 4.0N.

[0031] According to the pants-type absorbent article of form 1, when the waist member is worn in a highly stretched state (elongation 80%), the difference in magnitude of force between the stretching and contracting of the waist member in the left-right direction is 4.0 N or less, and the tightening force acting on the waist of the wearer becomes smaller than when the difference in magnitude of force is greater than 4.0 N. Therefore, even in a highly stretched state, the wearer can be worn loosely.

[0032] (Form 2)

[0033] According to the shorts-type absorbent article described in form 1, wherein, in the left-right direction, the difference between the magnitude of the force used to stretch the length of the waist member from a natural state to 60% of the most stretched length and the magnitude of the force used to shrink the length of the waist member from a most stretched state to 60% of the most stretched length is less than 2.5N.

[0034] According to the pants-type absorbent article of form 2, the difference in force between the stretched and contracted states when the waist member is worn in a low-stretched state (stretching rate 60%) is 2.5 N or less, and the tightening force is smaller than when the difference in force is greater than 2.5 N. Therefore, the pants can be worn loosely even in a low-stretched state.

[0035] (Form 3)

[0036] A shorts-type absorbent article according to form 1 or 2, wherein, in the left-right direction, the difference between the magnitude of the force used to stretch the length of the waist member from a natural state to 85% of the most stretched length and the magnitude of the force used to shrink the length of the waist member from a most stretched state to 85% of the most stretched length is less than 4.0N.

[0037] According to the pants-type absorbent article of form 3, the difference in force between the extension and contraction of the waist member when worn in a highly extended state (elongation 85%) is 4.0 N or less, and the tightening force is weaker than when the difference in force is greater than 4.0 N. Therefore, even in the maximum extended state assumed in the normal use form, the pants can be worn loosely.

[0038] (Form 4)

[0039] A shorts-type absorbent article according to any one of forms 1 to 3, wherein in the left-right direction, the ratio of the magnitude of the force used to shrink the length of the waist member from the most stretched state to 50% of the most stretched length divided by the magnitude of the force used to stretch the length of the waist member from the natural state to 50% of the most stretched length is greater than 50%.

[0040] According to the shorts-type absorbent article of form 4, the magnitude of the force acting when the waist member contracts is 50% or more of the magnitude of the force acting when it is stretched, and the force during contraction is less likely to be reduced compared to a case where it is less than 50%. Therefore, when the waist member is worn in a low stretch state (50%), it is easy to prevent the position of the waist member from being shifted due to insufficient tightening force.

[0041] (Form 5)

[0042] A shorts-type absorbent article according to any one of forms 1 to 4, wherein in the left-right direction, the ratio of the magnitude of the force used to contract the length of the waist member from the most stretched state to 60% of the most stretched length divided by the magnitude of the force used to stretch the length of the waist member from the natural state to 60% of the most stretched length is greater than 60%.

[0043] According to the shorts-type absorbent article of form 5, the magnitude of the force acting when the waist member contracts is 60% or more of the magnitude of the force acting when it is stretched, and the force during contraction is less likely to be reduced compared to a case where the force is less than 60%. Therefore, when the waist member is worn in a low stretch state (60%), it is easy to prevent the position of the waist member from being shifted due to insufficient tightening force.

[0044] (Form 6)

[0045] The pants-type absorbent article according to any one of aspects 1 to 5, wherein the increase ratio of the force when the waist member is stretched from 50% to 85% of its most stretched length in the left-right direction is 30N or less.

[0046] According to the pants-type absorbent article of form 6, the increase ratio of the force when the waist member is stretched within the range of 50% to 85% is 30 N or less, and the waist member is easily stretched more gently than when the force is greater than 30 N. Therefore, it is possible to suppress a sharp increase in the tightening force in the waist member, and it is easy to wear loosely.

[0047] (Form 7)

[0048] The pants-type absorbent article according to aspect 6, wherein the increase ratio of the magnitude of the force when the waist member is stretched from 75% to 85% of the most stretched length in the left-right direction is 44N or less.

[0049] According to the pants-type absorbent article of form 7, the increase ratio of the force when the waist member is stretched within the range of 75% to 85% is 44 N or less, and the waist member is easily stretched more gently than when the force is greater than 44 N. Therefore, even in a highly stretched state, the waist member can be worn loosely.

[0050] (Form 8)

[0051] A shorts-type absorbent article according to any one of forms 1 to 7, wherein, in the up-down direction, in an area below the central position of the pair of side joints, in the left-right direction, the difference between the magnitude of the force used to stretch the length of the waist member from a natural state to 80% of the most stretched length and the magnitude of the force used to shrink the length of the waist member from the most stretched state to 80% of the most stretched length is less than 1.5N.

[0052] According to the shorts-type absorbent article of form 8, the difference in magnitude of the force during extension and during contraction is 1.5 N or less at the lower part of the waist member overlapping the absorbent body and the absorbent core, and the difference in magnitude of the force during extension and during contraction is smaller than when the difference is greater than 1.50 N. Therefore, even in a highly extended state, the shorts can be worn loosely, and the positional displacement of the absorbent body and the absorbent core can be easily suppressed.

[0053] (Form 9)

[0054] A shorts-type absorbent article according to any one of forms 1 to 8, wherein, in the area below the central position of the pair of side joints in the up-down direction, the difference between the magnitude of the force when the length of the waist member is stretched from a natural state to 80% of the length when it is most stretched and the magnitude of the force when the length of the waist member is contracted to 80% of the length when it is most stretched from the natural state in the left-right direction is smaller than the difference between the magnitude of the force when the length of the waist member is stretched from a natural state to 80% of the length when it is most stretched and the magnitude of the force when the length of the waist member is contracted to 80% of the length when it is most stretched from the natural state in the left-right direction in the area above the central position of the pair of side joints in the up-down direction.

[0055] According to the shorts-type absorbent article of form 9, when the waist member is worn in a highly extended state (80%), the difference in the magnitude of the force when the lower side portion is extended and contracted is smaller than the difference in the magnitude of the force when the upper side portion of the waist member is extended and contracted. Therefore, the waist member as a whole can maintain a loose feeling, and the lower side portion overlapping with the absorbent body can suppress the large stretching force in the left and right directions from acting on the absorbent body, making it difficult to cause positional displacement of the absorbent body.

[0056] (Form 10)

[0057] A shorts-type absorbent article according to any one of forms 1 to 9, wherein, in the up-down direction, in an area above the center position of the pair of side joints, in the left-right direction, the difference between the magnitude of the force when stretching the length of the waist member from a natural state to 85% of the most extended length and the magnitude of the force when contracting the length of the waist member from the most extended state to 85% of the most extended length is less than 1.35N.

[0058] According to the shorts-type absorbent article of form 10, even when worn in the maximum stretched state (85%) assumed in the normal usage form, the difference in the magnitude of the force during stretching and during contraction is less than 1.35N at the upper side of the waist member where the wearer can easily feel the tightening. Compared with the case where the difference in the magnitude of the force is greater than 1.35N, the tightening force becomes weaker, and the article can be easily worn loosely.

[0059] (Form 11)

[0060] A shorts-type absorbent article according to any one of forms 1 to 10, wherein in the up-down direction, in an area below the central position of the pair of side joints, in the left-right direction, the ratio of the force required to shrink the length of the waist member from the most stretched state to 50% of the most stretched length divided by the force required to stretch the length of the waist member from the natural state to 50% of the most stretched length is greater than 50%.

[0061] According to the shorts-type absorbent article of form 11, the magnitude of the force acting on the lower side portion 2 of the waist member during contraction is 50% or more of the magnitude of the force acting on the lower side portion 2 during extension, and the force during contraction is less likely to be excessively reduced compared to a case where the force is less than 50%. Therefore, even when the shorts-type absorbent article is worn in a low extension state (50%), the tightening force due to the waist member can be suppressed from being insufficient at the lower side portion overlapping the absorbent body, and the positional displacement of the absorbent body is less likely to occur.

[0062] (Form 12)

[0063] A shorts-type absorbent article according to any one of forms 1 to 11, wherein in the up-down direction, in an area below the central position of the pair of side joints, in the left-right direction, the ratio of the force required to contract the length of the waist member from the most stretched state to 60% of the most stretched length divided by the force required to stretch the length of the waist member from the natural state to 60% of the most stretched length is greater than 60%.

[0064] According to the shorts-type absorbent article of form 12, the magnitude of the force acting on the lower side of the waist member during contraction is 60% or more of the magnitude of the force acting on the lower side of the waist member during extension, and the force during contraction is less likely to be excessively reduced compared to a case where the force is less than 60%. Therefore, even when the waist member is worn in a state where the extension rate is 60%, which is slightly higher than 50%, the tightening force due to the waist member can be suppressed from being insufficient at the lower side portion overlapping with the absorbent body, and the positional displacement of the absorbent body is less likely to occur.

[0065] (Form 13)

[0066] A shorts-type absorbent article according to any one of forms 1 to 12, wherein the waist member has a plurality of elastic members that can be stretched and contracted in the left-right direction at intervals in the up-down direction between a first sheet and a second sheet joined by a plurality of welded portions, and each of the elastic members is sandwiched between two adjacent welded portions in the up-down direction among the plurality of welded portions in a state contracted in the left-right direction, thereby being attached to the waist member.

[0067] According to the pants-type absorbent article of form 13, by attaching the waist elastic member to the waist member using a plurality of scattered welded parts, the stretching force exhibited by the waist member can be easily adjusted, and even in a highly stretched state, the tightening force can be prevented from becoming excessively large.

[0068] ===Implementation Method===

[0069] As an example of the pants-type absorbent article according to the embodiment of the present invention, a pants-type diaper 1 (hereinafter, also simply referred to as "diaper 1") will be described. The pants-type absorbent article also includes pants-type sanitary napkins, pants-type absorbent pads, and the like.

[0070] <Basic structure of diaper 1>

[0071] Figure 1 This is a schematic perspective view showing a structural example of the diaper 1 according to the present embodiment. Figure 2 This is a schematic plan view of the diaper 1 in the unfolded and stretched state as viewed from the skin side in the thickness direction. Figure 3 yes Figure 2 Schematic diagram of the AA section.

[0072] The "stretched state" of the diaper 1 refers to a state in which the diaper 1 as a whole (the entire product) is stretched without wrinkles by stretching the elastic members (e.g., the waist elastic members 25 and the leg elastic members 27 described later) of the diaper 1. Specifically, it refers to a state in which the dimensions of the components constituting the diaper 1 (e.g., the absorbent body 10 and the waist elastic members 20 described later) are the same as or close to the dimensions of the components alone. On the other hand, the stretched state refers to a state in which the diaper 1 is stretched without wrinkles by stretching the elastic members (e.g., the waist elastic members 25 and the leg elastic members 27 described later) of the diaper 1. Figure 1 Such a state is called the natural state. The "natural state" refers to the state when the diaper 1 is left for a predetermined time. For example, the waist member 20 of the diaper 1 is stretched to both sides in the left and right directions to become the "stretched state", and after the stretched state is maintained for 15 seconds, the diaper 1 is released from the stretch and placed on a flat surface such as a table. Then, the state after 5 minutes of being placed flat on such a flat surface is called the natural state.

[0073] Diapers 1 in Figure 1 The shorts-type state shown has mutually orthogonal "up and down directions", "left and right directions" and "front and back directions". Figure 3 As shown in FIG. 1 , the diaper 1 has a "thickness direction" which is the direction in which the components are stacked. The side that becomes the waist side of the wearer when the wearer wears the diaper 1 in the up-down direction is referred to as the "upper side", and the side that becomes the crotch side of the wearer is referred to as the "lower side". In addition, the side that becomes the belly side of the wearer when the wearer wears the diaper 1 in the front-back direction is referred to as the "front side", and the side that becomes the back side of the wearer is referred to as the "rear side". In addition, the side that contacts the skin of the wearer when the wearer wears the diaper 1 in the thickness direction is referred to as the "skin side", and the opposite side is referred to as the "non-skin side".

[0074] In addition, diaper 1 Figure 2 In the unfolded state shown, the pants have a "longitudinal direction" and a "lateral direction" that are orthogonal to each other. The "longitudinal direction" is a direction along the up-down direction of the pants type, and the "lateral direction" is a direction along the left-right direction of the pants type.

[0075] The diaper 1 of this embodiment includes a liquid-absorbent main body 10 that absorbs liquid such as urine, and a waist member 20 that is joined to the non-skin side of the absorbent main body 10 and is disposed around the waist of the wearer when the diaper 1 is worn.

[0076] (Absorbent body 10)

[0077] Figure 4 1 is a top view and a cross-sectional view of the absorbent body 10. Figure 2 As shown in FIG. 1 , the absorbent body 10 of this embodiment is in a generally rectangular shape when viewed from above, with the longitudinal direction (i.e., the length direction of the absorbent body 10) along the vertical direction of the diaper 1. Figure 3 and Figure 4 As shown, the absorbent body 10 has an absorbent core 11 along the longitudinal direction (up and down direction), a top sheet 12 arranged at a position closer to the skin side than the absorbent core 11, a back sheet 13 arranged at a position closer to the non-skin side than the absorbent core 11, and a pair of side sheets 15, 15 arranged on both sides of the absorbent core 11 in the lateral direction (left and right direction).

[0078] The absorbent core 11 is a member for absorbing and retaining excretion fluid such as urine, and can be exemplified by forming liquid-absorbent fibers such as pulp containing a superabsorbent polymer (SAP) into a predetermined shape. Figure 4 As shown, the absorbent core 11 of this embodiment is formed into a substantially hourglass shape with the central portion of the longitudinal direction narrowing inwardly in the left-right direction, but the shape of the absorbent core 11 is not limited thereto. In addition, the outer peripheral surface of the absorbent core 11 may also be covered by a liquid-permeable sheet member (core wrap sheet 11b) such as a tissue.

[0079] The top sheet 12 is a liquid-permeable sheet member that can come into contact with the wearer's skin when worn, and is formed of, for example, a hydrophilic air-through nonwoven fabric, a spunbond nonwoven fabric, or the like. Figure 4 In the cross-sectional view of , the left and right ends of the top sheet 12 are folded into the position closer to the non-skin side than the absorbent core 11, so that the top sheet 12 wraps the absorbent core 11 from the skin side. In addition, it can also be that a second sheet not shown in the figure is provided between the top sheet 12 and the absorbent core 11.

[0080] The back sheet 13 is a liquid-impermeable and breathable sheet member (breathable sheet member) for preventing liquid such as urine absorbed by the absorbent core 11 from leaking to the outside, and is formed of a liquid-impermeable film such as polyethylene or polypropylene.

[0081] The side sheet 15 is a sheet member disposed on both sides of the absorbent core 11 in the lateral direction, and for example, a hydrophobic nonwoven fabric such as SMS (spunbond-meltblown-spunbond) nonwoven fabric can be used. One end side of the side sheet 15 in the up-down direction (left-right direction) is bent to be located at a position closer to the non-skin side than the absorbent core 11 and the back sheet 13. On the other hand, the other end side of the side sheet 15 in the up-down direction (left-right direction) is bent to be located at a position closer to the skin side than the absorbent core 11 and the top sheet 12, and a pair of leak-proof wall portions 30, 30 are formed on both sides of the absorbent body 10.

[0082] A pair of anti-leakage walls 30 are provided on both sides of the absorbent body 10 in the lateral direction (left-right direction), and are portions corresponding to so-called three-dimensional gathers. When the diaper 1 is worn, the anti-leakage walls 30 stand up toward the skin side of the wearer at both sides of the absorbent body 10 in the left-right direction, thereby preventing excretion fluids such as urine from leaking out to the outside of the absorbent body 10 in the left-right direction along the wearer's skin. In addition, the anti-leakage walls 30 may be respectively composed of two or more sheet members (side sheets 15).

[0083] like Figure 4As shown in the cross-sectional view of , the side sheet 15 is folded back multiple times to form a stacked state in the thickness direction, and the leakage-proof wall elastic member 35 is arranged between the stacked side sheets 15 in a longitudinally stretched state. When the diaper 1 is worn, the end 15t of the leakage-proof wall portion 30 is contracted in the longitudinal direction (up and down direction) based on the elasticity of the leakage-proof wall elastic member 35, so that the absorbent body 10 is easily fitted around the legs of the wearer.

[0084] (Waist member 20)

[0085] The waist member 20 is a sheet member disposed on the non-skin side of the absorbent body 10, and includes a skin side sheet 21, non-skin side sheets 22, 23, and a cover sheet 24. Figure 2 As shown, the waist member 20 is formed at the front side ( Figure 1 The portion overlapping the side joint 40 (described later) at the front side of the front-to-back direction of the waist member 20 is defined as the "front waist portion FA". Similarly, the waist member 20 is defined as the portion overlapping the side joint 40 (described later) at the front side of the front-to-back direction of the waist member 20 formed at the rear side ( Figure 1 The portion where the side joint 40 overlaps at the position of the front side (the rear side in the front-to-back direction) is defined as the "rear waistline BA". Furthermore, the portion between the rear end of the front waistline FA in the longitudinal direction and the front end of the rear waistline BA is defined as the "crotch CA".

[0086] The skin side sheet 21 is a sheet member disposed on the skin side of the waist member 20, and is formed of, for example, spunbonded nonwoven fabric, SMS nonwoven fabric, etc. Figure 2 As shown, the skin side sheet 21 is continuous from the front side (ventral side) to the back side (dorsal side) in the longitudinal direction, and has a shape that is narrowed inward in the left-right direction at the crotch portion CA. This narrowed portion becomes the leg opening 1b (described later) in the pants-type diaper 1.

[0087] The non-skin side sheet 22 is a sheet member stacked on the non-skin side of the skin side sheet 21 on the front side (ventral side) in the longitudinal direction, and is formed by a spunbond nonwoven fabric, an SMS nonwoven fabric, etc., similarly to the skin side sheet 21. The skin side sheet 21 and the non-skin side sheet 22 are mutually joined by a plurality of fusion bonding portions 50, 50... described later in a state of being stacked in the thickness direction. In addition, a plurality of waist elastic members 25, 25... are provided between the skin side sheet 21 and the non-skin side sheet 22. A plurality of waist elastic members 25, 25... are arranged at intervals in the longitudinal direction (up and down direction), and are respectively installed between the skin side sheet 21 and the non-skin side sheet 22 in a state of being stretched in the transverse direction (left and right direction). As a result, the waist elastic member 25 exhibits elasticity in the transverse direction (left and right direction), and this elasticity is used to impart elasticity to the front waist portion FA of the waist member 20.

[0088] As an example, the waist elastic member 25 can be formed of an elastic resin material mainly composed of a thermoplastic elastic resin formed into a rubber band shape. As the above-mentioned thermoplastic elastic resin, for example, a thermoplastic resin that exhibits rubber elasticity at room temperature is preferably used, and for example, thermoplastic elastomers described in JIS K 6418: 2007 can be cited. The above-mentioned thermoplastic elastic resin is preferably a thermoplastic elastic resin whose elastic deformation temperature range is about 100° C. or less. As the above-mentioned thermoplastic elastic resin, for example, olefin elastomers (such as VERSIFY (trademark) of Dow Chemical Company), propylene elastomers (such as Vistamaxx (trademark) of ExxonMobil Corporation), styrene elastomers (such as Quintac (trademark) of Japan Zeon Co., Ltd.) and the like can be cited.

[0089] The non-skin side sheet 23 is a sheet member stacked on the non-skin side of the skin side sheet 21 on the rear side (back side) in the longitudinal direction, and has the same structure as the non-skin side sheet 22. That is, the non-skin side sheet 23 is joined to the skin side sheet 21 through a plurality of welded portions 50, 50..., and a plurality of waist elastic members 25, 25... are arranged between the skin side sheet 21 and the non-skin side sheet 23 so as to be stretchable in the lateral direction (left-right direction).

[0090] The cover sheet 24 is a sheet member which is laminated on the non-skin side of the skin side sheet 21 on the rear side (back side) in the longitudinal direction, similarly to the non-skin side sheet 23. Figure 3 As shown, the cover sheet 24 is located at a lower side (front side in the longitudinal direction) than the non-skin side sheet 23 in the vertical direction, and is partially overlapped with the non-skin side sheet 23. Hereinafter, the portion where the cover sheet 24 overlaps with the non-skin side sheet 23 in the vertical direction (longitudinal direction) is also referred to as the "back overlapping portion LB".

[0091] The cover sheet 24 is bonded to the skin side sheet 21 and a portion of the non-skin side sheet 23 via an adhesive surface 75 made of an adhesive such as a hot melt adhesive. In addition, a leg elastic member 27 made of an elastic cord or the like is provided between the cover sheet 24 and the skin side sheet 21 in the thickness direction (see Figure 3). The leg elastic member 27 is attached to the waist member 20 via an adhesive portion 70 made of an adhesive such as a hot melt adhesive applied to a specified area of ​​the non-skin side of the skin side sheet 21. In the present embodiment, the leg elastic member 27 has: a straight portion 27a, wherein the portion overlapping with the absorbent body 10 (absorbent core 11) is arranged in a straight line along the horizontal direction at the central portion in the horizontal direction (left-right direction); and a curved portion 27b, wherein the curved portion 27b is arranged in a curved manner along the contour of the leg opening 1b on both sides in the horizontal direction. By fixing substantially the entire area of ​​the leg elastic member 27 by means of the adhesive portion 70, the shape of the straight portion 27a and the curved portion 27b in the leg elastic member 27 can be maintained. In addition, by means of the elasticity exhibited by the leg elastic member 27, the leg opening 1b is easily fitted around the legs of the wearer on the back side when the diaper 1 is worn, and the portion of the waist member 20 covering the buttocks of the wearer is difficult to rise.

[0092] In addition, the waist member 20 has the skin side sheet 21 and the non-skin side sheets 22 and 23 partially folded back downward at the upper end in the vertical direction. Figure 3 In the embodiment, the skin side sheet 21 and the non-skin side sheet 22 form a front folded portion 20Ff, which is a portion folded back toward the lower side in the vertical direction and the skin side in the thickness direction at the front folded position FL20f located at the front upper end of the waist member 20. The front folded portion 20Ff is bonded to the sheet member (in the thickness direction) adjacent to the front sheet member 20 by an adhesive such as a hot melt adhesive. Figure 3 At least a portion of the skin side sheet 21 and the top sheet 12 of the absorbent body 10 are joined to each other.

[0093] Similarly, in Figure 3 In the embodiment, the skin side sheet 21 and the non-skin side sheet 23 form a rear folded portion 20Fb, which is a portion folded back toward the lower side (the front side in the longitudinal direction) and the skin side in the thickness direction at the rear folded position FL20b located at the rear upper end of the waist member 20. The rear folded portion 20Fb is bonded to the sheet member (in the thickness direction) adjacent to the rear sheet member 20 by an adhesive such as a hot melt adhesive. Figure 3 At least a portion of the skin side sheet 21 and the top sheet 12 of the absorbent body 10 are joined to each other.

[0094] In addition, in the diaper 1, the front folded portion 20Ff may be formed by folding back only one sheet member of the skin side sheet 21 and the non-skin side sheet 22 at the front folded position FL20f. Similarly, the rear folded portion 20Fb may be formed by folding back only one sheet member of the skin side sheet 21 and the non-skin side sheet 23 at the rear folded position FL20b. That is, the folded portions 20Ff and 20Fb may be formed by one sheet member, respectively.

[0095] Alternatively, a separate sheet member may be provided at a position closer to the skin than the folded portions 20Ff and 20Fb. For example, the sheet member may be arranged so as to span from the skin side of the lower edge of the folded portions 20Ff and 20Fb in the vertical direction. Figure 3 (not shown in the figure), thereby preventing the lower end edges of the folded portions 20Ff and 20Fb from biting into the wearer's skin when the diaper 1 is worn.

[0096] Diapers 1 from Figure 2 From the unfolded state shown, the center position CL in the longitudinal direction (at Figure 2 The absorbent body 10 and the waist member 20 are folded in half in the longitudinal direction (indicated by a single dotted line) as the folded position. In this folded state, the lateral sides 20fe, 20fe of the front waist portion FA and the lateral sides 20be, 20be of the rear waist portion BA in the waist member 20 that overlap in the front-to-back direction are joined using a known joining method such as sealing welding to form a pair of side joining parts 40, 40. As a result, the waist member 20 after folding is connected in a ring shape at the front side (ventral side) and the rear side (dorsal side), forming a waist member 20 having a folded shape. Figure 1 The diaper 1 is a pants-type diaper 1 having a waist opening 1a and a pair of leg openings 1b as shown.

[0097] <About Attachment of Waist Elastic Member 25>

[0098] A specific method of attaching the waist elastic members 25 and the leg elastic members 27 to the waist member 20 will be described. First, a method of attaching the waist elastic members 25 will be described.

[0099] Figure 5 This is a diagram for explaining a range in which a plurality of welded portions 50 are formed in the waist member 20 . Figure 6 It is a diagram for explaining an example of the arrangement of the welded portion 50 . Fig. 7A and Figure 7B This is a diagram for explaining the principle of attaching the waist elastic member 25 to the waist member 20 using the welded portion 50 .

[0100] In the waist member 20 of the diaper 1, the skin side sheet 21 and the non-skin side sheets 22, 23 are joined by a plurality of welded portions 50, 50, etc. formed by welding means such as known ultrasonic welding. Figure 5 In the figure, during the manufacturing process of the diaper 1, when the non-skin side sheets 22, 23 (equivalent to the second sheet) are joined to the non-skin side of the skin side sheet 21 (equivalent to the first sheet), the area where the welded portion 50 is formed is indicated by the oblique line portion. In addition, at the stage of joining the skin side sheet 21 to the non-skin side sheets 22, 23, the leg opening 1b is not yet formed (the sheet member is not cut). Figure 5In FIG. 1 , the position of the absorbent body 10 (absorbent core 11 ) is indicated by a dotted line. However, at the stage of forming the welded portion 50 , the absorbent body 10 is not yet joined to the waist member 20 .

[0101] like Figure 5 As shown, the skin side sheet 21 and the non-skin side sheets 22, 23 are joined at the portions overlapping in the thickness direction in the stretched state before being bent at the front bending position FL20f and the rear bending position FL20b. That is, a welded portion 50 is formed in the range spanning the bending positions FL20f and FL20b in the front and rear. Figure 5 Within the range indicated by the oblique line portion, the waist elastic components 25, 25... which can be stretched and retracted along the left and right directions are sandwiched between the skin side pieces 21 (first piece) and the non-skin side pieces 22, 23 (second piece) opposite to each other in the thickness direction in a manner that a plurality of them are arranged at intervals in the up and down direction (longitudinal direction), and are installed based on the welding parts 50, 50...

[0102] In the waist member 20 of this embodiment, Figure 6 As shown, by arranging a plurality of welded portions 50, 50 ... at intervals in the vertical direction (longitudinal direction), a welded portion row 60 along the vertical direction is formed, and a plurality of welded portion rows 60 are arranged at intervals in the left-right direction (lateral direction). Figure 6 In order to simplify the description, the configuration and number of the waist elastic member 25 and the welded portion 50 are schematically shown. Each welded portion row 60 is configured to have a convex portion 60P protruding to one side or the other side in the left-right direction. That is, by making the positions of the multiple welded portions 50 included in the welded portion row 60 different from each other in the left-right direction, the welded portion row 60 is formed to have concave and convex as a whole. Figure 6 In the example of FIG. 5 , the welded portion row 60 is formed to bend left and right from the upper side to the lower side in the vertical direction. However, the arrangement of each welded portion 50 is not limited to Figure 6 For example, the welded portion row 60 may have the convex portion 60P only on one side in the left-right direction. In addition, the welded portion row 60 may not have concavities and convexities in the left-right direction but may be arranged straightly in the up-down direction.

[0103] The waist elastic member 25 is attached to the waist member 20 by sandwiching the waist elastic member 25 vertically with two welded portions 50, 50 adjacent to each other in the vertical direction among the plurality of welded portions 50, 50 ... included in the welded portion row 60. That is, a pair of welded portions 50, 50 arranged on both sides of the waist elastic member 25 in the vertical direction form a welded portion pair 50s, and the waist elastic member 25 is attached using the welded portion pair 50s.

[0104] like Fig. 7AAs shown, a pair of welded portions 50, 50 forming a welded portion pair 50s are arranged at intervals GH50 in the vertical direction. In addition, the size of the interval GH50 is set to the same size as the outer diameter D25t of the waist elastic member 25 such as the elastic line under the state of the target elongation ratio in the left-right direction or a slightly larger size (GH50≥D25t) than it. That is, the waist elastic member 25 in the stretched state is configured between the welded portion pair 50s in the vertical direction. According to such a structure, in the manufacturing process of the diaper 1, after the waist elastic member 25 in the stretched state is configured between the skin side piece 21 and the non-skin side piece 22 (23), when the skin side piece 21 is joined to the non-skin side piece 22 (23), the welded portion 50 can be formed without overlapping with the waist elastic member 25. Here, the “extension ratio” is a value R (= L1 / L0 ) indicating how many times the total length L1 of the waist elastic member 25 is stretched to its natural length compared to the total length L0 in the unloaded state.

[0105] Then, when the waist elastic member 25 relaxes from the stretched state, as shown in FIG. Figure 7B As shown, the waist elastic member 25 shrinks in the left-right direction and expands in the up-down direction, and the expanded outer diameter D25t' is larger than the interval GH50 in the up-down direction of the welding part pair 50s (D25t'>GH50). Therefore, the expansion of the waist elastic member 25 in the up-down direction is restricted between the welding part pair 50s, and thus, the waist elastic member 25 is substantially in a state of being sandwiched and pressed by the welding parts 50, 50 in the up-down direction. As a result, the position of the waist elastic member 25 in the up-down direction and the left-right direction is restricted by the welding part pair 50s, and the waist elastic member 25 can be installed on the waist member 20 in a stretchable manner, and the waist member 20 is given stretchability in the left-right direction.

[0106] Since the skin side sheet 21 (first sheet) and the non-skin side sheets 22, 23 (second sheet) are joined by the joining means, that is, the welding part 50 using ultrasonic welding or the like, it is possible to firmly ensure the joining strength of the waist member 20. In addition, since the welding parts are dispersedly arranged, it is easy to maintain the softness of the waist member 20, and the skin touch can be improved.

[0107] Furthermore, in the diaper 1 in the shorts-type state, since the waist elastic member 25 is joined at both ends of the waist member 20 in the left-right direction by the side joints 40, the waist elastic member 25 will not be detached from the waist member 20 even if the waist member 20 stretches in the left-right direction when the diaper 1 is worn.

[0108] <About the tightening force when wearing diaper 1>

[0109] When wearing a pants-type absorbent article such as the diaper 1, the wearer's legs are respectively passed through a pair of leg openings 1b, 1b, and the waist member 20 and the absorbent body 10 are pulled up to the crotch side and fit the wearer's body. At this time, the waist member 20 is stretched in the left-right direction from the natural state, and the elasticity of the waist elastic member 25 generates a tightening force along the circumference of the waist opening 1a, so that the waist member 20 fits the wearer's waist.

[0110] However, in general shorts-type diapers, the length of the waist member in the left-right direction (the circumference of the waist opening) is not always constant when the wearer wears the diaper. For example, when the wearer moves his body or breathes, the circumference of the waist changes, and the waist member expands and contracts in the left-right direction according to the change. In addition, in conventional shorts-type diapers, as the waist member expands and contracts in the left-right direction, the tightening force acting on the wearer's waist increases, which may cause the wearer to feel oppressive and uncomfortable. In particular, when the shorts-type diaper is worn in a so-called high-stretch state in which the length of the waist member in the left-right direction is about 80% of the maximum stretch (equivalent to the above-mentioned stretch state), the tightening force associated with the expansion and contraction of the waist member increases, making it difficult to wear the diaper loosely.

[0111] In contrast, in the diaper 1 of the present embodiment, the waist elastic member 25 is attached to the waist member 20 by using a plurality of scattered welded portions 50, so that the stretching force exhibited by the waist member 20 can be adjusted, and even in a highly stretched state, the tightening force can be prevented from becoming excessively large. The following describes the results of a test on the tightening force of the waist member 20 using the diaper 1 of the present embodiment and conventional pants-type diapers A to F as comparative examples.

[0112] FIG8 is a diagram for explaining the concept of a tensile test for measuring the tightening force of the waist member 20. First, both ends of the waist member 20 of the diaper 1 in a natural state are stretched in the left-right direction to form a Fig. 8A The waist member 20 is in the stretched state as shown in FIG. 1 (i.e., stretched to a state where the left-right dimension of the waist member 20 is consistent with the dimension of the member alone). Fig. 8A The state of the waist member 20 is called the "maximum stretched state". That is, the "maximum stretched state" refers to the state when the waist member 20 is stretched most in the left-right direction. The length of the waist member 20 in the left-right direction in the maximum stretched state is defined as L1.

[0113] Next, the diaper 1 is returned to its natural state, and the two ends (e.g., the position of the side joint 40) of the waist member 20 of the diaper 1 are clamped by the chucks of a known tensile tester (e.g., a universal material testing machine manufactured by Instron). At this time, the interval between the chucks of the tensile tester is set to 180 mm. In addition, the interval of 180 mm between the chucks is less than the length of the waist member 20 in the left-right direction in the natural state. From this state (i.e., the natural state), the waist member 20 is stretched to both sides in the left-right direction at a stretching speed of 300 mm / min, so that the waist member 20 is stretched to the maximum stretched state. Next, the waist member 20 in the maximum stretched state is contracted at a speed of 300 mm / min until the length in the left-right direction returns to 180 mm. This cycle is repeated twice. In addition, during the stretching of the first cycle, the length of the waist member 20 in the left-right direction is stretched to a specified length L (refer to Figure 8B ) is measured and recorded. In addition, during the second cycle of contraction, the length of the waist member 20 in the left and right directions is contracted to a predetermined length L (refer to Figure 8B ) is measured and recorded.

[0114] Thus, the magnitude of the force when the length of the waist member 20 in the left-right direction is extended to (L / L1)% of the maximum extension state and the magnitude of the force when it is contracted to (L / L1)% of the maximum extension state are measured, and the magnitude of the tightening force accompanying the expansion and contraction of the waist member 20 is evaluated. In addition, as a comparative example, the conventional shorts-type diapers A to F available on the market were also measured under the same conditions and compared with the diaper 1.

[0115] Fig. 9 This is a table showing the results of the tensile test on Diaper 1 and Comparative Examples A to F.

[0116] Fig.10 This is a graph showing the relationship between the elongation of the waist member and the magnitude of the force during extension and contraction for Diaper 1 and Comparative Examples A and B. Fig. 9 In the figure, the magnitude of the force (N) when the waist member 20 is stretched or contracted to the left-right length L of the waist member 20 relative to the left-right length L1 of the waist member 20 in the maximum stretched state is shown for each stretch rate (L / L1) of the waist member 20. For example, the force when the waist member 20 of the diaper 1 is stretched in the left-right direction from the natural state to L / L1=0.5 (i.e., the stretch rate is 50%) is 3.61 N. In addition, the force when the waist member 20 of the diaper 1 is contracted in the left-right direction from the maximum stretched state to L / L1=0.5 (the stretch rate is 50%) is 2.19 N.

[0117] also, Fig. 9 The range of elongation (0.5 to 0.85) shown is the range of expansion and contraction of the waist member 20 assumed when the diaper 1 and the comparative examples A to F are worn. That is, in the normal use form of the diaper 1, the waist member 20 is extended or contracted in the left-right direction within the range of elongation of 0.5 to 0.85. In addition, hereinafter, the range of 0.5 to 0.6 (50% to 60%) of the relatively low elongation of the waist member 20 is defined as the "low elongation state", and the range of 0.75 to 0.85 (75% to 85%) of the relatively high elongation is defined as the "high elongation state".

[0118] exist Fig. 9 In the figure, the magnitude of the force when the waist member 20 of the diaper 1 is stretched from the natural state to an elongation of 0.80 (80% of the length at the maximum stretch) is 11.07 N. On the other hand, the magnitude of the force when the waist member 20 is contracted from the maximum stretch state to an elongation of 0.80 is 9.00 N. This means that when the diaper 1 is worn in a highly stretched state with an elongation of about 0.80, a force of 11.07 N is applied when the waist member 20 is stretched in the left-right direction due to the wearer's body movement, and a force of 9.00 N is applied when the waist member 20 is contracted in the left-right direction. Furthermore, the difference between the magnitude of the force when stretched and when contracted, i.e., 2.07 N (=11.07-9.00), acts on the waist of the wearer as a tightening force accompanying the expansion and contraction of the waist member 20.

[0119] In contrast, the tightening force under the same conditions (elongation of 0.80) in the pants-type diapers of Comparative Examples A to F is greater than that of Diaper 1. For example, in Comparative Example A, the difference in force between the stretching and the stretching at an elongation of 0.8 (80%) is 4.56 N (= 13.62 - 9.06), which is significantly greater than that of Diaper 1 (refer to Fig.10 Similarly, in Comparative Example B, the difference in force between the stretching and the stretching at an elongation of 0.8 is 4.79 N (= 10.72 - 5.93), which is a greater force than that of Diaper 1 (refer to Fig.10 Thus, in Comparative Examples A to F, in a high elongation state of about 0.80 elongation, a tightening force greater than 4.0 N acts on the waist of the wearer (see Fig. 9 , Fig.10 ).

[0120] In the diaper 1 of the present embodiment, when the waist member 20 is worn in a highly stretched state (80%), the difference in magnitude of force between the stretching and contracting of the waist member 20 in the left-right direction due to the wearer's body movement is 4.0 N or less, and the tightening force acting on the wearer's waist becomes smaller than when the difference in magnitude of force is greater than 4.0 N. That is, in the diaper 1 of the present embodiment, it is possible to wear the wearer "loosely" even in a highly stretched state.

[0121] In fact, whether the wearer feels "loose" when the waist member 20 of the diaper 1 is worn in a highly stretched state (80%) can be evaluated by performing a sensory test. For example, when 10 test subjects perform a predetermined action (such as walking) while wearing the diaper 1 in a highly stretched state (80%), if the proportion of people who feel discomfort or unpleasantness is less than 2, the diaper 1 can be worn "loosely".

[0122] In addition, in the diaper 1 of the present embodiment, even when the waist member 20 is worn in a low elongation state of about 0.60, it can be worn "loosely". Specifically, in the diaper 1, the magnitude of the force required to stretch the waist member 20 from the natural state to an elongation of 0.60 (60% of the length at the maximum elongation) is 5.83N. On the other hand, the magnitude of the force required to shrink the waist member 20 from the maximum elongation state to an elongation of 0.60 is 4.29N. That is, the difference in the magnitude of the force when the diaper 1 is stretched and when it is contracted when it is worn in a low elongation state of 60% is 1.54N (=5.83-4.29) (refer to Fig. 9 ).

[0123] In contrast, in Comparative Examples A to F, the difference in force between the extension and contraction when the garment was worn at an extension rate of 0.60 (low extension state) was greater than 2.50 N (see Fig. 9 ), it is known that a larger tightening force than that of the diaper 1 is applied. That is, in the diaper 1, the difference in magnitude of the force between the stretched and contracted state when the waist member 20 is worn in a low stretched state (60%) is 2.5N or less, and the tightening force is weaker than when the difference in magnitude of the force is larger than 2.5N, so that the diaper can be worn loosely even in the low stretched state.

[0124] In addition, in the diaper 1, even when the waist member 20 is worn in the maximum elongation state (the elongation of the waist member 20 is 0.85) assumed in the normal use form, it can be worn "loosely". Specifically, in the diaper 1, the magnitude of the force when the waist member 20 is stretched from the natural state to the elongation of 0.85 (85% of the length when stretched to the maximum) is 13.71N. On the other hand, the magnitude of the force when the waist member 20 is contracted from the maximum elongation state to the elongation of 0.85 is 11.77N. That is, the difference in the magnitude of the force when the diaper 1 is stretched and contracted when it is worn in the high elongation state of 85% is 1.94N (=13.71-11.77).

[0125] In contrast, in Comparative Examples A to F, the difference in force between the extension and contraction when the garment was worn at an elongation of 0.85 (high elongation state) was greater than 4.0 N (see Fig. 9 ), it is known that a larger tightening force than that of the diaper 1 is applied. That is, in the diaper 1, the difference in magnitude of the force between the stretched and contracted state when the waist member 20 is worn in a highly stretched state (85%) is 4.0 N or less, and the tightening force is weaker than when the difference in magnitude of the force is greater than 4.0 N, so that the diaper can be worn loosely even in the maximum stretch state that can be imagined.

[0126] The following is explained: the diaper 1 of this embodiment does not tighten too much in the low-stretch state to the high-stretch state compared with the conventional pants-type diaper, and can be worn loosely. However, in the pants-type diaper, if the waist member is too loose, it is easy to cause positional deviation, etc., and the fit may be deteriorated. In particular, when the waist member is worn in the low-stretch state with an elongation rate of about 0.5 to 0.6, the tightening force based on the waist member may be too weak.

[0127] For example, in Comparative Example C, the magnitude of the force when the waist member is stretched from the natural state to an elongation of 0.50 (50% of the length at the maximum elongation) is 8.72 N, and the magnitude of the force when it is contracted from the maximum elongation state to an elongation of 0.50 is 3.81 N. In addition, the value obtained by dividing the force during contraction by the force during extension when worn in a low elongation state (50%) is 43.7% (=3.81 / 8.72). That is, the magnitude of the force acting during contraction is less than half of the magnitude of the force acting during extension. In this case, the force during contraction becomes excessively small, which may cause insufficient tightening force of the waist portion and easily cause positional displacement. In addition, in any case of Comparative Examples A to F, the value obtained by dividing the force during contraction by the force during extension is less than 43.7% (less than 50%), and in the low elongation state (50%), positional displacement may easily occur during contraction.

[0128] On the other hand, in the diaper 1 of the present embodiment, the magnitude of the force when the waist member 20 is stretched from the natural state to an elongation of 0.50 is 3.61 N, and the magnitude of the force when it is retracted from the maximum elongation state to an elongation of 0.50 is 2.19 N. Furthermore, the value obtained by dividing the force during contraction by the force during extension when the diaper is worn in a low elongation state (50%) is 60.7% (=2.19 / 3.61). That is, the magnitude of the force acting on the waist member 20 during contraction is more than 50% of the magnitude of the force acting during extension, and the force during contraction is less likely to be excessively reduced compared to a case where the force is less than 50%. Therefore, even when the diaper 1 is worn in a low elongation state (50%), it is difficult for the waist member 20 to be positionally displaced.

[0129] In addition, when the elongation of the waist member 20 is set to 0.6, which is slightly higher than 0.5, in Comparative Example A, the magnitude of the force when the waist member is stretched from the natural state to the elongation of 0.60 is 6.72 N, and the magnitude of the force when it is contracted from the maximum elongation state to the elongation of 0.60 is 3.64 N. And, the value obtained by dividing the force during contraction by the force during extension is 54.2% (=3.64 / 6.72). In addition, in any of Comparative Examples A to F, the value obtained by dividing the force during contraction by the force during extension is 54.2% or less (less than 60%).

[0130] On the other hand, in the diaper 1 of the present embodiment, the magnitude of the force applied when the waist member 20 is stretched from the natural state to an elongation of 0.60 is 5.83 N, and the magnitude of the force applied when the waist member 20 is stretched from the maximum elongation state to an elongation of 0.60 is 4.29 N. Furthermore, the value obtained by dividing the force applied when the waist member 20 is stretched by the force applied when the waist member 20 is stretched is 73.6% (= 4.29 / 5.83). That is, the magnitude of the force applied when the waist member 20 is stretched is more than 60% of the magnitude of the force applied when the waist member 20 is stretched, and the force applied when the waist member 20 is stretched is less likely to be excessively reduced compared to a case where the force applied when the waist member 20 is stretched is less than 60%. Therefore, even when the diaper 1 is worn in a low elongation state (60%), it is less likely that the position of the waist member 20 will be displaced.

[0131] When the diaper 1 is worn, the waist member 20 is pulled from the toes side to the crotch side of the wearer while the waist opening 1a and the leg opening 1b are expanded by stretching the waist member 20 to both sides in the left-right direction. At this time, the waist member 20 is stretched from the low-stretched state to the high-stretched state. In the diaper 1, the ratio of the increase in force when the waist member 20 is greatly stretched in this way is limited to a predetermined value or less, thereby preventing the tightening force by the waist member 20 from becoming excessively large.

[0132] In the diaper 1, when the waist member 20 in the natural state is stretched in the left-right direction, the ratio of the force increase when it is stretched from 50% of the maximum stretch state to 85% is 28.85N (= (13.71-3.61) / (0.85-0.50)). Fig.10 The inclination when the elongation of the diaper 1 changes from 0.5 to 0.85 is 28.85 N (30 N or less).

[0133] On the other hand, in Comparative Example B, the ratio of the increase in force when the waist member 20 is stretched in the left-right direction from 50% of the maximum stretched state to 85% is 31.41N (=(13.35-2.35) / (0.85-0.50)). In addition, in any of Comparative Examples A to F, the ratio of the increase in force when the waist member 20 is stretched from 50% of the maximum stretched state to 85% is greater than 30N, which is a value greater than that of Diaper 1. That is, in Diaper 1, the ratio of the increase in force when the waist member 20 is stretched within the range of elongation of 0.5 to 0.85 is less than 30N, and the waist member 20 is easier to stretch smoothly than when it is greater than 30N. As a result, it is possible to suppress a sharp increase in the tightening force, and it is easy to wear the diaper 1 loosely.

[0134] In addition, by limiting the increase in the force when the waist member 20 of the diaper 1 is stretched within the range of elongation of 0.75 to 0.85 (i.e., in the high elongation state) to below a specified value, it is possible to prevent excessive tightening even in the high elongation state. Specifically, when the waist member 20 is stretched in the left-right direction from 75% of the maximum elongation state to 85%, the increase in the force is 43.5N (= (13.71-9.36) / (0.85-0.75)). That is, Fig.10 The inclination when the elongation of the diaper 1 changes from 0.75 to 0.85 is 43.52 N (less than 44 N).

[0135] On the other hand, in Comparative Example B, the ratio of the increase in force when the waist member 20 is stretched in the left-right direction from 75% of the maximum stretched state to 85% is 45.0 N (= (13.35-8.85) / (0.85-0.75)). In addition, in any of Comparative Examples A to F, the ratio of the increase in force when the waist member 20 is stretched from 75% of the maximum stretched state to 85% is greater than 44 N, which is a value greater than that of Diaper 1. That is, in Diaper 1, the ratio of the increase in force when the waist member 20 is stretched within the range of elongation of 0.75 to 0.85 is less than 44 N, and compared with the case where it is greater than 44 N, it can be worn loosely even in a highly stretched state.

[0136] In addition, the upper part and the lower part of the waist member 20 of the diaper 1 were subjected to a tensile test in the same manner as described above when the waist member 20 was divided into two equal parts in the vertical direction. Specifically, the part of the front waist member FA (the rear waist member BA) shown in FIG. 8 that is above the central position FAC (corresponding to the central position of the side joint 40) in the vertical direction is set as the upper part FA1, and the part that is below the central position FAC is set as the lower part FA2. In addition, the waist member 20 was cut along the left-right direction at the central position FAC in the vertical direction to be divided into the upper part FA1 and the lower part FA2, and the upper part FA1 and the lower part FA2 were subjected to a tensile test in the same manner as described above.

[0137] Fig.11 This is a table showing the results of the tensile test on the lower side portion FA2 of the diaper 1 and Comparative Examples A to F. Fig.12 This is a graph showing the relationship between the elongation rate of the lower side portion FA2 of the waist member and the magnitude of the force during extension and contraction for the diaper 1 and comparative examples A and B. Fig.13 This is a table showing the results of the tensile test on the upper side portion FA1 of the diaper 1 and Comparative Examples A to F. Fig.14 This is a graph showing the relationship between the elongation of the upper part FA1 of the waist member and the magnitude of the force during extension and contraction for Diaper 1 and Comparative Examples A and B. In addition, Comparative Examples A to F were also divided into a portion above and a portion below the center position in the vertical direction of the front waist portion (rear waist portion) in the same manner as Diaper 1, and a tensile test was performed.

[0138] exist Fig.11 The magnitude of the force applied when the lower side portion FA2 of the waist member 20 of the diaper 1 is stretched from the natural state to an elongation of 0.80 (80% of the length at the maximum elongation) is 4.72 N. On the other hand, the magnitude of the force applied when the lower side portion FA2 of the waist member 20 is contracted from the maximum elongation state to an elongation of 0.80 is 3.48 N. Furthermore, the difference between the magnitude of the force applied when stretched and when contracted is 1.24 N (=4.72-3.48), which is less than 1.50 N.

[0139] On the other hand, in Comparative Example D, the magnitude of the force when the waist member is stretched from the natural state to an elongation of 0.80 is 4.33 N, and the magnitude of the force when it is contracted from the maximum stretched state to an elongation of 0.80 is 2.79 N. Moreover, the difference in magnitude of the force when stretched and contracted is 1.54 N (= 4.33-2.79). In addition, in any of Comparative Examples A to F, the difference in magnitude of the force when stretched and contracted is greater than 1.50 N, which is a value greater than that of Diaper 1.

[0140] That is, in the diaper 1 of the present embodiment, when the waist member 20 is worn in a highly stretched state (80%), the difference in magnitude of the force during stretching and during contraction at the lower side portion FA2 is 1.5 N or less, and the difference in magnitude of the force during stretching and during contraction is smaller than when it is greater than 1.50 N. Since the lower side portion FA2 is a portion overlapping the absorbent body 10 and the absorbent core 11 (see FIG. 8 ), by reducing the difference in magnitude of the force during stretching and during contraction at the lower side portion FA2, it is possible to suppress the positional displacement of the absorbent body 10 and the absorbent core 11 caused by the expansion and contraction of the waist member 20 in the left-right direction, and the diaper 1 can be worn loosely.

[0141] In addition, Fig.13 The force required to extend the upper side portion FA1 of the waist member 20 of the diaper 1 from the natural state to an extension rate of 0.80 is 7.13 N. On the other hand, the force required to contract the upper side portion FA1 of the waist member 20 from the maximum extension state to an extension rate of 0.80 is 5.68 N. The difference between the force required to extend and contract is 1.45 N (=7.13-5.68).

[0142] Therefore, when the waist member 20 is worn in a highly stretched state (80%), the difference in the magnitude of the force between the stretching and contracting of the lower side portion FA2 (1.24 N) is smaller than the difference in the magnitude of the force between the stretching and contracting of the upper side portion FA1 of the waist member 20 (1.45 N). As a result, the loose feeling of the waist member 20 can be maintained, and the lower side portion FA2 overlapping with the absorbent body 10 can suppress the large stretching force in the left-right direction from acting on the absorbent body 10, and the positional displacement of the absorbent body 10 is less likely to occur.

[0143] In addition, Fig.13 The force applied when the upper side portion FA1 of the waist member 20 of the diaper 1 is stretched from the natural state to an elongation of 0.85 is 8.69 N, and the force applied when the upper side portion FA1 of the waist member 20 is contracted from the maximum stretched state to an elongation of 0.85 is 7.39 N. The difference between the force applied when stretched and when contracted is 1.3 N (=8.69-7.39), which is less than 1.35 N.

[0144] On the other hand, in Comparative Example B, the magnitude of the force when the waist member is stretched from the natural state to an elongation of 0.85 is 5.02 N, and the magnitude of the force when it is contracted from the maximum stretched state to an elongation of 0.80 is 3.65 N. Moreover, the difference in magnitude of the force when stretched and contracted is 1.37 N (=5.02-3.65). In addition, in any of Comparative Examples A to F, the difference in magnitude of the force when stretched and contracted is greater than 1.35 N, which is a value greater than that of Diaper 1.

[0145] That is, in the diaper 1, even when the waist member 20 is worn in the maximum stretched state (85%) assumed in the normal usage mode, the difference in the magnitude of the force during stretching and contraction at the upper side portion FA1 of the waist member 20, which is easily noticeable by the wearer, is less than 1.35N. Compared with the case where the difference in the magnitude of the force is greater than 1.35N, the tightening force becomes weaker, and the diaper can be easily worn loosely.

[0146] In addition, Fig.11 The force required to stretch the lower side portion FA2 of the waist member 20 of the diaper 1 from the natural state to 0.50% is 1.46N, and the force required to shrink the lower side portion FA2 from the maximum stretched state to 0.50% is 0.77N.

[0147] Furthermore, the value obtained by dividing the contraction force by the extension force when worn in a low extension state (50%) was 52.7% (=0.77 / 1.46), which was 50% or more.

[0148] On the other hand, in Comparative Example A, the magnitude of the force when the waist member is stretched from the natural state to an elongation of 0.50 is 2.19 N, and the magnitude of the force when it is retracted from the maximum elongation state to an elongation of 0.50 is 0.94 N. Moreover, the value obtained by dividing the force during retraction by the force during extension is 42.9% (= 0.94 / 2.19). In addition, in any of Comparative Examples A to F, the value obtained by dividing the force during retraction by the force during extension is less than 50%, which is a value smaller than that of Diaper 1.

[0149] That is, the magnitude of the force acting on the lower side portion FA2 of the waist member 20 of the diaper 1 during contraction is 50% or more of the magnitude of the force acting on the waist member 20 during extension, and the force during contraction is less likely to be excessively reduced compared to a case where the force is less than 50%. Therefore, even when the diaper 1 is worn in a low extension state (50%), the positional deviation of the absorbent body 10 due to insufficient tightening force of the waist member 20 can be suppressed at the lower side portion FA2 overlapping the absorbent body 10.

[0150] In addition, Fig.11 The force required to stretch the lower side portion FA2 of the waist member 20 from the natural state to 0.60 is 2.39 N, and the force required to shrink the lower side portion FA2 from the maximum stretch state to 0.50 is 1.56 N. Furthermore, the value obtained by dividing the force during shrinkage by the force during extension when worn in a low stretch state (50%) is 65.3% (=1.56 / 2.39), which is 60% or more.

[0151] On the other hand, in Comparative Example A, the magnitude of the force when the waist member is stretched from the natural state to an elongation of 0.60 is 3.38 N, and the magnitude of the force when it is retracted from the maximum elongation state to an elongation of 0.60 is 1.87 N. Moreover, the value obtained by dividing the force during retraction by the force during extension is 55.3% (=1.87 / 3.38). In addition, in any of Comparative Examples A to F, the value obtained by dividing the force during retraction by the force during extension is less than 60%, which is a value smaller than that of Diaper 1.

[0152] That is, the magnitude of the force acting on the lower side portion FA2 of the waist member 20 of the diaper 1 during contraction is 60% or more of the magnitude of the force acting on the lower side portion FA2 during extension, and the force during contraction is less likely to be excessively reduced compared to a case where the force is less than 60%. Therefore, even when the diaper 1 is worn in a state where the elongation of the waist member 20 is 60%, which is slightly higher than 50%, the positional deviation of the absorbent body 10 caused by insufficient tightening force of the waist member 20 can be suppressed at the lower side portion FA2 overlapping the absorbent body 10.

[0153] ===Others===

[0154] The above-mentioned embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can of course be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

[0155] In the above embodiment, as an example of a pants-type absorbent article, a diaper 1 (see FIG. 1 ) is described in which the skin side sheet 21 in the waist member 20 is continuously formed from one side (front side) to the other side (rear side) in the longitudinal direction and is integrally formed. Figure 3 The skin side sheet 21 may be formed separately on the front and rear sides. For example, the absorbent article may be a three-piece shorts-type absorbent article consisting of a front outer garment component (front waistline), a rear outer garment component (rear waistline) and an absorbent body.

[0156] The waist member 20 of the diaper 1 may be provided with a post-processing belt 80 at a predetermined position. The post-processing belt 80 is a substantially rectangular belt-shaped member (belt member) that is long in the vertical direction (longitudinal direction) and is made of a resin material such as polyethylene or polypropylene.

[0157] In diaper 1, as Figure 2 and Figure 3As shown, the post-processing belt 80 is provided on the non-skin side of the waistline portion BA on the rear side of the waistline member 20 (the non-skin side of the non-skin side sheet 23). One side of the post-processing belt 80 in the vertical direction is fixed to the waistline member 20, and the other side in the vertical direction has an adhesive portion. An adhesive is applied to the adhesive portion, and before using the diaper 1, a part of the post-processing belt 80 is folded with the adhesive portion as the inner side so that the adhesive portion is not exposed to the outside and the adhesive surface is protected.

[0158] When the used diaper 1 is disposed, the diaper 1 rolled up in the vertical direction with the absorbent body 10 facing inside is pulled while the folded post-processing tape 80 is stretched to expose the adhesive portion, and the adhesive portion is rolled around the diaper 1. Thus, the diaper 1 can be kept in the rolled-up state, and the diaper 1 can be disposed without the excrement and the like adhering to the inside of the diaper 1 (absorbent body 10) leaking out.

[0159] Description of Reference Numerals

[0160] 1Diapers (pants-type absorbent articles),

[0161] 1a waist opening, 1b leg opening,

[0162] 10 Absorbent body,

[0163] 11 absorbent core, 11b core wrapping sheet,

[0164] 12 top pieces, 13 back pieces, 15 side pieces, 15t ends,

[0165] 20 waist components,

[0166] 20Ff front folded portion, 20Fb rear folded portion,

[0167] 21 skin side piece, 22 non-skin side piece, 23 non-skin side piece, 24 cover piece, 25 waist

[0168] Elastic components,

[0169] 27 leg elastic member, 27a straight portion, 27b curved portion,

[0170] 30 leak-proof wall,

[0171] 35 leak-proof wall elastic component,

[0172] 40 side joint,

[0173] 50 welding part, 50s welding part pair,

[0174] 60 welding parts,

[0175] 70 bonding part, 75 bonding surface,

[0176] 80 post-processing belt (belt component),

[0177] 91 intermittent department, 92 intermittent department,

[0178] E1 is a first elastic member, E2 is a second elastic member,

[0179] CL Central Location,

[0180] FA front waist, FA1 front upper part, FA2 front lower part, FAC middle part,

[0182] BA rear waistline,

[0183] CA inseam,

[0184] FL20f is the front bending position, FL20b is the rear bending position.

Claims

1. A shorts-type absorbent article, the shorts-type absorbent article having an up-down direction, a left-right direction, and a front-back direction intersecting each other, The pants-type absorbent article comprises a liquid-absorbent main body and a waist member having stretchability in the left-right direction. The waist member includes a front waist portion provided at the front side in the front-rear direction and a rear waist portion provided at the rear side in the front-rear direction. The front waistline portion and the rear waistline portion are joined to each other by a pair of side joints provided on both sides in the left-right direction, wherein: In the left-right direction, The difference between the force required to extend the waist member to 80% of its most extended length from a natural state and the force required to contract the waist member to 80% of its most extended length from its most extended state is 4.0 N or less.

2. The pants-type absorbent article according to claim 1, characterized in that In the left-right direction, The difference between the force required to extend the waist member to 60% of its most extended length from a natural state and the force required to contract the waist member to 60% of its most extended length from a most extended state is 2.5 N or less.

3. The pants-type absorbent article according to claim 1 or 2, characterized in that: In the left-right direction, The difference between the force required to extend the waist member to 85% of its most extended length from a natural state and the force required to contract the waist member to 85% of its most extended length from its most extended state is 4.0 N or less.

4. The pants-type absorbent article according to claim 3, characterized in that: In the left-right direction, The ratio of the force required to shrink the waist member to 50% of its most stretched length from its most stretched state divided by the force required to stretch the waist member to 50% of its most stretched length from its natural state is 50% or more.

5. The pants-type absorbent article according to claim 3, characterized in that: In the left-right direction, The ratio of the force required to shrink the waist member to 60% of its most stretched length from the most stretched state divided by the force required to stretch the waist member to 60% of its most stretched length from the natural state is 60% or more.

6. The pants-type absorbent article according to claim 3, characterized in that: In the left-right direction, the increase ratio of the magnitude of the force when the waist member is stretched from a state of 50% to a state of 85% of the length when stretched most is 30N or less.

7. The pants-type absorbent article according to claim 6, characterized in that: In the left-right direction, the increase ratio of the magnitude of the force when the waist member is stretched from a state of 75% to a state of 85% of the length when stretched most is 44 N or less.

8. The pants-type absorbent article according to claim 3, characterized in that: In the up-down direction, in a region below the center position of the pair of side joints, In the left-right direction, The difference between the force required to stretch the waist member to 80% of its most stretched length from a natural state and the force required to shrink the waist member to 80% of its most stretched length from a most stretched state is 1.5 N or less.

9. The pants-type absorbent article according to claim 8, characterized in that: In the vertical direction, in an area below the center position of the pair of side joints, in the left-right direction, the difference between the magnitude of the force when the length of the waist member is stretched from the natural state to 80% of the length when it is most stretched and the magnitude of the force when the length of the waist member is contracted from the most stretched state to 80% of the length when it is most stretched is less than In the up-down direction, in an area above the center position of the pair of side joints, in the left-right direction, the difference between the magnitude of the force when the length of the waist member is stretched from a natural state to 80% of the length when it is most stretched and the magnitude of the force when the length of the waist member is contracted from the most stretched state to 80% of the length when it is most stretched.

10. The pants-type absorbent article according to claim 3, characterized in that: In the up-down direction, in a region above the center position of the pair of side joints, In the left-right direction, The difference between the force required to stretch the waist member to 85% of its most stretched length from a natural state and the force required to shrink the waist member to 85% of its most stretched length from its most stretched state is 1.35 N or less.

11. The pants-type absorbent article according to claim 3, characterized in that: In the up-down direction, in a region below the center position of the pair of side joints, In the left-right direction, The ratio of the force required to shrink the waist member to 50% of its most stretched length from its most stretched state divided by the force required to stretch the waist member to 50% of its most stretched length from its natural state is 50% or more.

12. The pants-type absorbent article according to claim 3, characterized in that: In the up-down direction, in a region below the center position of the pair of side joints, In the left-right direction, The ratio of the force required to shrink the waist member to 60% of its most stretched length from the most stretched state divided by the force required to stretch the waist member to 60% of its most stretched length from the natural state is 60% or more.

13. The pants-type absorbent article according to claim 3, characterized in that: The waist member includes a plurality of elastic members that are stretchable in the left-right direction and are spaced apart in the up-down direction between the first sheet and the second sheet joined by the plurality of welded portions. Each of the elastic members is attached to the waist member by being sandwiched between two welded portions adjacent to each other in the up-down direction among the plurality of welded portions in a state contracted in the left-right direction.

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