Absorbent article

Abstract

To provide an absorbent article that prevents itself from slipping down and leaves few marks on a wearer's skin.SOLUTION: An absorbent article 1 has an absorbent body 2 and an exterior body 3, provided with a side seal part S, a waist opening WH and a leg opening LH. The exterior body 3 includes an easy stress relaxation member 34 and an anti-stress relaxation member 33 and also has a flexible area for the waist W and a flexible area around the hips D. The flexible area for the waist W has the number of the anti-stress relaxation members 33 per unit length in the longitudinal direction X that is smaller than that in the flexible area around the hips D. The flexible area for the waist W has a stress holding rate after a relaxation test that is smaller than that in the flexible area around the hips D, the relaxation test in which the absorbent article 1 has been stretched at a 1.4-fold factor and let stand for 10 hours at the room temperature of 40°C.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to absorbent articles.

Background Art

[0002] Many of the currently commercially available absorbent articles such as disposable diapers, which have an opening in the waist area of the wearer, have elasticity in the vicinity of the waist opening in order to suppress displacement. As a method of imparting elasticity to the vicinity of the waist opening, there is a method of disposing an elastic member such as thread rubber in the vicinity of the waist opening in the outer wrapper of the diaper. The applicant has previously proposed an absorbent article described in Patent Document 1 as such an absorbent article. In Patent Document 1, the vicinity of the waist opening in the outer wrapper is composed of a stretch sheet, a non-stretch sheet disposed on the skin-facing side of the stretch sheet, and an elastic member disposed between both sheets.

[0003] In an absorbent article in which an elastic member is disposed in the vicinity of the waist opening in the outer wrapper, by adjusting the stress of the elastic member, it is possible to achieve both suppression of displacement and difficulty in leaving marks. For example, in the iliac region where the abdominal circumference variation is small, the stress of the elastic member is increased, and in the waist stretch region, the stress of the elastic member is decreased.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, it is difficult to sufficiently suppress the appearance of marks of the absorbent article on the wearer by only adjusting the stress of the elastic member. In particular, when the wearer is a child with a large body, marks are likely to appear. Even in the absorbent article of Patent Document 1, there is room for improvement in preventing the appearance of marks of the absorbent article on the wearer. Therefore, an object of the present invention is to provide an absorbent article that can solve the drawbacks of the above-described prior art.

Means for Solving the Problems

[0006] The present invention includes an absorbent main body and an exterior body disposed on the non-skin facing surface side of the absorbent main body, It has a ventral part arranged on the ventral side of the wearer, a dorsal part arranged on the dorsal side of the wearer, and a crotch part located between the ventral part and the dorsal part, and has a longitudinal direction corresponding to the direction extending from the ventral part through the crotch part to the dorsal part and a transverse direction orthogonal to the longitudinal direction. The present invention relates to a pant-type absorbent article in which both side portions of the ventral part and both side portions of the dorsal part are joined to form a pair of side seal portions, a waist opening, and a pair of leg openings. The exterior body includes an easy stress relaxation member as a stretchable member and a difficult stress relaxation member that is less stress-relaxing than the easy stress relaxation member, and a waist stretch region that is located on the opening end side of the waist opening and stretches in the transverse direction rather than the edge of the absorbent main body in the longitudinal direction, and a body circumference stretch region that is located on the crotch part side rather than the edge of the absorbent main body in the longitudinal direction. In the waist stretch region, the number of the difficult stress relaxation members per unit length in the longitudinal direction is less than that in the body circumference stretch region. The waist stretch region has an elongation magnification of 1.4 times, and the stress retention rate after the relaxation test after being left at a temperature of 40°C for 10 hours is smaller than that in the body circumference stretch region.

[0007] The present invention also includes an absorbent main body and an exterior body disposed on the non-skin facing surface side of the absorbent main body, It relates to a pant-type absorbent article having a ventral part arranged on the ventral side of the wearer, a dorsal part arranged on the dorsal side of the wearer, and a crotch part located between the ventral part and the dorsal part, having a longitudinal direction corresponding to the direction extending from the ventral part through the crotch part to the dorsal part and a transverse direction orthogonal to the longitudinal direction, and a pair of side seal parts, a waist opening, and a pair of leg openings being formed by joining both side parts of the ventral part and both side parts of the dorsal part. The outer package includes, as a stretchable member, an easy stress relaxation member and a difficult stress relaxation member that is less likely to relax stress than the easy stress relaxation member, and has a waist stretchable region that is located on the opening end side of the waist opening rather than the edge of the absorbent body in the longitudinal direction and stretches in the transverse direction, and a body circumference stretchable region that is located on the crotch side rather than the edge of the absorbent body in the longitudinal direction. In the waist stretchable region, the number of the difficult stress relaxation members per unit length in the longitudinal direction is less than that in the body circumference stretchable region. The waist stretchable region is stretched in the transverse direction until it reaches a length of 71% of the length of the pant-type absorbent article in the maximum stretched state, and the stress retention rate after the standard relaxation test after being left at a temperature of 40°C for 10 hours is smaller than that in the body circumference stretchable region.

Advantages of the Invention

[0008] According to the present invention, it is possible to suppress displacement and provide an absorbent article that is less likely to leave marks on the wearer.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 11

MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, the present invention will be described based on its preferred embodiments. FIGS. 1 to 6 show a pant-type disposable diaper (hereinafter referred to as "diaper") 1, which is an embodiment of the absorbent article of the present invention. As shown in FIGS. 1 to 3, the diaper 1 includes a ventral part A arranged on the ventral side of the wearer during wearing, a dorsal part B arranged on the dorsal side of the wearer, and a crotch part C located therebetween. The diaper 1 also has a longitudinal direction X corresponding to the direction extending from the ventral part A through the crotch part C to the dorsal part B and a transverse direction Y orthogonal to the longitudinal direction X. In FIG. 1, the symbol Cy indicates the center line along the longitudinal direction X of the diaper 1.

[0011] As shown in FIGS. 1 to 3, the diaper 1 includes an absorbent body 2 and an outer cover 3 disposed on the non-skin-facing surface side of the absorbent body 2. The outer cover 3 includes a ventral outer cover 3A disposed on the ventral side portion A and a dorsal outer cover 3B disposed on the dorsal side portion B. The absorbent body 2 is fixed so as to span between the ventral outer cover 3A and the dorsal outer cover 3B.

[0012] In the diaper 1, both side portions 3e, 3e along the longitudinal direction X of the ventral outer cover 3A and both side portions 3f, 3f along the longitudinal direction X of the dorsal outer cover 3B are joined to form a pair of side seal portions S, S, a waist opening WH, and a pair of leg openings LH, LH.

[0013] As shown in FIG. 4, the absorbent body 2 has an absorber 23, a surface sheet 21 disposed on the skin-facing surface side of the absorber 23, and a back sheet 22 disposed on the non-skin-facing surface side of the absorber 23. Similar to the absorbent body 2, the absorber 23 has a shape that is long in the longitudinal direction X of the diaper 1 and is interposed between the surface sheet 21 and the back sheet 22.

[0014] The "skin-facing surface" is the surface of the diaper 1 or its component member (for example, the absorber 23) that faces the wearer's skin when the diaper 1 is worn, and the "non-skin-facing surface" is the surface that faces the side opposite to the wearer's skin when the diaper 1 is worn. Also, "when worn" and "worn state" refer to the state in which the diaper 1 is worn while maintaining an appropriate wearing position.

[0015] As described above, the outer body 3 includes a ventral outer body 3A and a dorsal outer body 3B. In the present embodiment, the ventral outer body 3A and the dorsal outer body 3B have a waist elastic region W located on the opening end WE side of the waist opening WH rather than the edges 2a, 2b of the absorbent body 2 in the longitudinal direction X, and a body circumferential elastic region D located on the crotch C side rather than the edges 2a, 2b of the absorbent body 2. The total length of the waist elastic region W and the body circumferential elastic region D in the longitudinal direction X is the same as the length of the side seal portion S. The waist elastic region W and the body circumferential elastic region D expand and contract in the lateral direction Y. The waist elastic region W of the ventral outer body 3A and the waist elastic region W of the dorsal outer body 3B are continuous, and a cylindrical waist elastic region W is formed as a whole. The body circumferential elastic region D of the ventral outer body 3A and the body circumferential elastic region D of the dorsal outer body 3B are continuous, and a cylindrical body circumferential elastic region D is formed as a whole. The dorsal outer body 3B has an extension region E extending from the body circumferential elastic region D toward the crotch C side.

[0016] In the present invention, the outer body has, as a stretching member, an easy stress relaxation member and a difficult stress relaxation member that is more difficult to relax stress than the easy stress relaxation member. A stretching member is a member having a property of being stretchable and contracting when the stretching force is released, and stress relaxation means that the contraction force decreases by maintaining the stretched state for a predetermined time. In the embodiment shown in FIG. 1, the ventral outer body 3A and the dorsal outer body 3B have an outer layer sheet 32, an inner layer sheet 31 disposed on the skin-facing surface side of the outer layer sheet 32, a plurality of elastic members 33 disposed between the two sheets 31, 32, and a stretching sheet 34 disposed on the non-skin-facing surface side of the outer layer sheet 32. In the present embodiment, the stretching sheet 34 is an easy stress relaxation member, and the elastic member 33 is a difficult stress relaxation member. The stretching sheet 34 is disposed across the waist elastic region W and the body circumferential elastic region D. The stretching sheet 34 and the outer layer sheet

[0017] Regarding the stress relaxation ease of the easy stress relaxation member and the difficult stress relaxation member, the magnitude of the stress relaxation ease can be determined by comparing the magnitudes of the stress retention rates after the material relaxation test measured by the following first measurement method. The larger the value of the stress retention rate after the material relaxation test, the more difficult it is to relax the stress. <First Measurement Method of Stress Retention Rate after Material Relaxation Test> By the following method, for each of the easy stress relaxation member and the difficult stress relaxation member, after obtaining the measurement samples before and after the stress relaxation test respectively, a tensile test is performed on each of the obtained measurement samples. (1) Method for Creating Measurement Sample before Stress Relaxation Test Take out the easy stress relaxation member and the difficult stress relaxation member from the diaper, and obtain measurement samples from each of the taken-out easy stress relaxation member and difficult stress relaxation member. For both the easy stress relaxation member and the difficult stress relaxation member, when in sheet form, the dimensions of the measurement sample are such that the dimension in the direction corresponding to the lateral direction of the diaper is 150 mm, and the dimension in the direction corresponding to the longitudinal direction of the diaper is 40 mm. For both the easy stress relaxation member and the difficult stress relaxation member, when in string form (filament form), one easy stress relaxation member and one difficult stress relaxation member are used as the measurement sample, and the dimension of the measurement sample is such that the dimension in the direction corresponding to the lateral direction of the diaper is 150 mm. If it is not possible to obtain a measurement sample of the above-described dimensions from the easy stress relaxation member or the difficult stress relaxation member, obtain a measurement sample with the largest possible dimensions. (2) Method for Creating Measurement Sample after Stress Relaxation Test (2-1) Marking Mark a rectangle on the part of the diaper where the easy stress relaxation member and the difficult stress relaxation member are arranged, with the lateral dimension of the diaper being 150 mm and the longitudinal dimension of the diaper being 40 mm. Then, perform the following stress relaxation test. If it is not possible to mark the diaper with the above-described dimensions, mark it with the largest possible dimensions. (2-2) Stress Relaxation Test The diaper is stretched so that the inner dimension of the diaper becomes 1.4 times the inner dimension in the natural state of the diaper, and the diaper is stored at 40 °C for 10 hours. The inner dimension of the diaper means the distance between the side seal portions of the outer package in the lateral direction of the diaper. When the inner dimension of the diaper is not constant in the longitudinal direction of the diaper, the inner dimension of the diaper is measured at 10 mm intervals in the longitudinal direction, and the average value thereof is taken as the inner dimension. (2-3) Extraction of measurement samples From the diaper after the stress relaxation test, the portion marked with the mark is cut out. Then, an easily stress-relaxing member and a difficult stress-relaxing member are taken out from the cut-out portion, and each is used as a measurement sample. For both the stress-relaxing member and the difficult stress-relaxing member, in the case of a string-like shape (filamentous case), one easily stress-relaxing member and one difficult stress-relaxing member are used as the measurement sample. (3) Tensile test For each measurement sample obtained by the above (1) and (2), a tensile test is performed using a tensile testing machine. Specifically, each measurement sample is fixed to the chuck of the tensile testing machine in a non-extended and non-relaxed state. At this time, for both ends in the longitudinal direction of the measurement sample, a portion 20 mm from the edge in the longitudinal direction of the measurement sample is clamped by the chuck. That is, when the length in the longitudinal direction of the measurement sample is 150 mm, the distance between the chucks is 110 mm. Then, the distance between the chucks is expanded at a speed of 300 mm / min. The stress at the time when the distance between the chucks reaches 1.4 times the initial length of the stretched portion is measured. In addition, the measurement sample after the stress relaxation test is subjected to a tensile test after standing for 1 hour after the stress relaxation test. The measurement result of the measurement sample before the stress relaxation test is taken as the stress S0 before storage, and the measurement result of the measurement sample after the stress relaxation test is taken as the stress S1 after storage, and the stress retention rate after the material relaxation test is calculated by the following formula 1. Stress retention rate after material relaxation test = S1 / S0 ··· (Formula 1) Compare the stress retention rate after the material relaxation test of the easily stress-relaxing member obtained in this way with the stress retention rate after the material relaxation test of the difficult stress-relaxing member. If the stress retention rate after the material relaxation test of the easily stress-relaxing member is smaller than the stress retention rate after the material relaxation test of the difficult stress-relaxing member, it is determined that the easily stress-relaxing member is more likely to relax stress than the difficult stress-relaxing member.

[0018] The stress retention rate after the material relaxation test can also be calculated using the stress S0 before storage and the stress S1 after storage measured by the following second measurement method. For example, when it is determined that the easily stress-relaxing member is more likely to relax stress than the difficult stress-relaxing member as described above, in addition to the stress retention rate after the material relaxation test of the easily stress-relaxing member obtained by the first measurement method being smaller than the stress retention rate after the material relaxation test of the difficult stress-relaxing member, or instead of that, it is preferable that the stress retention rate after the material relaxation test of the easily stress-relaxing member obtained by the second measurement method is smaller than the stress retention rate after the material relaxation test of the difficult stress-relaxing member. The stress retention rate after the material relaxation test calculated by the above-described first measurement method and the stress retention rate after the material relaxation test calculated by the second measurement method are substantially the same. Here, "substantially the same" means that the magnitude relationship between the stress retention rate after the material relaxation test of the easily stress-relaxing member and the stress retention rate after the material relaxation test of the difficult stress-relaxing member calculated by the first measurement method, and the magnitude relationship between the stress retention rate after the material relaxation test of the easily stress-relaxing member and the stress retention rate after the material relaxation test of the difficult stress-relaxing and easily stress-relaxing member calculated by the second measurement method do not change.

[0019] <Second Measurement Method for Stress Retention Rate after Material Relaxation Test> (1) Method for Creating a Measurement Sample before the Stress Relaxation Test Perform in the same manner as the method for creating a measurement sample before the stress relaxation test in (1) of the <First Measurement Method for Stress Retention Rate after Material Relaxation Test> described above. (2) Method for Creating a Measurement Sample after the Stress Relaxation Test (2-1) Application of Marks Perform in the same manner as the application of marks in (2-1) of the <First Measurement Method for Stress Retention Rate after Material Relaxation Test> described above. (2-2) Stress Relaxation Test Prepare a cylinder having a circumference that is twice the inner dimension of the diaper when the diaper is stretched in the lateral direction Y until it reaches 71% of the length in its maximum extended state. Put the diaper on the cylinder and store the diaper at 40°C for 10 hours in a state where the length of the diaper in the lateral direction Y is extended until it reaches 71% of the length in its maximum extended state. The inner dimension of the diaper means the distance between the side seal portions of the outer body in the lateral direction of the diaper. When the inner dimension of the diaper is not constant in the longitudinal direction of the diaper, measure the inner dimension of the diaper at 10 mm intervals in the longitudinal direction and use the average value as the inner dimension. (2-3) Removal of the measurement sample Perform in the same manner as the removal of the measurement sample in (2-3) of the above <First Measurement Method of Stress Retention Rate after Material Relaxation Test>. (3) Tensile test After fixing each measurement sample obtained in the above (1) and (2) to the chuck of a tensile testing machine, perform in the same manner as the (3) tensile test of the above <First Measurement Method of Stress Retention Rate after Material Relaxation Test>, except that the stress is measured at the point when the distance between the chucks reaches 71% of the length in the maximum extended state of the stretched portion.

[0020] The ratio of the stress retention rate after the material relaxation test of the easy stress relaxation member to the stress retention rate after the material relaxation test of the difficult stress relaxation member (stress retention rate after the material relaxation test of the easy stress relaxation member / stress retention rate after the material relaxation test of the difficult stress relaxation member) is preferably 0.10 or more, more preferably 0.20 or more, still more preferably 0.30 or more, preferably less than 1.00, more preferably 0.80 or less, still more preferably 0.60 or less, and preferably 0.10 or more and less than 1.00, more preferably 0.20 or more and 0.80 or less, still more preferably 0.30 or more and 0.50 or less, from the viewpoint of providing a difference in ease of stress relaxation to suppress the displacement of the diaper and not to tighten the abdominal circumference too much.

[0021] The stress retention rate after the material relaxation test of the easy stress relaxation member is preferably 0.10 or more, more preferably 0.20 or more, still more preferably 0.30 or more, preferably 0.70 or less, more preferably 0.60 or less, still more preferably 0.50 or less, and preferably 0.10 or more and 0.70 or less, more preferably 0.20 or more and 0.60 or less, still more preferably 0.30 or more and 0.50 or less, from the viewpoints of not over-tightening the abdominal circumference and suppressing displacement, and of moderately relaxing stress and achieving an optimal tightening stress when a large-sized wearer wears it.

[0022] The stress retention rate after the material relaxation test of the difficult stress relaxation member is preferably 0.50 or more, more preferably 0.60 or more, still more preferably 0.70 or more, and preferably less than 1.0, from the viewpoints of not over-tightening the abdominal circumference and suppressing displacement, and of maintaining a stress capable of suppressing displacement at least minimally when the easy stress relaxation member is excessively relaxed due to environmental temperature or body type.

[0023] In the present embodiment, in both the waist stretchable region W and the body circumferential stretchable region D, the elastic member 33 is arranged in an extended state along the lateral direction Y. Thereby, the waist stretchable region W and the body circumferential stretchable region D are stretchable in the lateral direction Y. The number of difficult stress relaxation members per unit length in the longitudinal direction X is different between the waist stretchable region W and the body circumferential stretchable region D. More specifically, the waist stretchable region W has fewer elastic members 33 per unit length along the longitudinal direction X than the body circumferential stretchable region D. In the present embodiment, although the elastic member 33 is arranged in the waist stretchable region W, the elastic member 33 may not be arranged in the waist stretchable region W. Also, by making the pitch of the difficult stress relaxation member in the longitudinal direction X different between the waist stretchable region W and the body circumferential stretchable region D, the number of difficult stress relaxation members per unit length in the longitudinal direction X can be made different between the waist stretchable region W and the body circumferential stretchable region D.

[0024] The waist stretch region W preferably has a number of elastic members 33 per unit length in the vertical direction X of 0.10 per 10 mm or more, more preferably 0.20 per 10 mm or more, still more preferably 0.25 per 10 mm or more, preferably 1.85 per 10 mm or less, more preferably 1.00 per 10 mm or less, and still more preferably 0.50 per 10 mm or less, on the condition that the number of elastic members 33 per unit length in the vertical direction X is less than that in the body circumferential stretch region D. By having the number of elastic members 33 per unit length in the vertical direction X within this range, the waist stretch region W can prevent excessive tightening around the abdomen and suppress slippage. Also, when worn by a larger-sized wearer, it can moderately relieve stress and provide an optimal tightening stress. The body circumferential stretch region D preferably has a number of elastic members 33 per unit length in the vertical direction X of 1.2 per 10 mm or more, more preferably 1.45 per 10 mm or more, still more preferably 1.70 per 10 mm or more, preferably 2.50 per 10 mm or less, more preferably 2.25 per 10 mm or less, and still more preferably 1.90 per 10 mm or less, on the condition that the number of elastic members 33 per unit length in the vertical direction X is more than that in the waist stretch region W. By having the number of elastic members 33 per unit length in the vertical direction X within this range, the body circumferential stretch region D can prevent excessive tightening around the abdomen and suppress slippage. Also, when the stress relaxation member excessively relaxes stress depending on the environmental temperature and body shape, it can maintain a stress that can at least suppress slippage.

[0025] Regarding the method for measuring the number of elastic members 33 per unit length, the method for measuring the number of elastic members 33 per unit length in the waist stretch region W will be described as an example. Measure the length Lw of the waist stretch region W in the vertical direction X. Also, let Nw be the number of elastic members 33 included in the waist stretch region W. Then, the number of elastic members 33 per unit length is calculated by the following formula 2. The unit length is 10 mm. Number of elastic members per unit length = [Nw (pieces) / Lw (mm)] × 10 mm ··· (Formula 2) The number of elastic members 33 per unit length in the circumferential expansion / contraction region D can also be obtained in the same manner. That is, assuming the length of the circumferential expansion / contraction region D in the longitudinal direction X is Ld (mm) and the number of elastic members 33 included in the circumferential expansion / contraction region D is Nd (pieces), it is obtained by the following formula 3. Number of elastic members per unit length = [Nd (pieces) / Ld (mm)] × 10 mm ··· (Formula 3)

[0026] In the diaper 1, the waist expansion / contraction region W has a stress retention rate after relaxation test greater than that of the circumferential expansion / contraction region D. The stress retention rate after relaxation test mentioned here means the stress retention rate after relaxation test (hereinafter also referred to as the "standard stress retention rate after relaxation test") when the elongation magnification is 1.4 times and left at a temperature of 40 °C for 10 hours. The standard stress retention rate after relaxation test can be measured by the following first measurement method. <First measurement method for standard stress retention rate after relaxation test> By the following method, after obtaining measurement pieces before and after the stress relaxation test from the measurement target region of the diaper, a tensile test is performed on each of the obtained measurement pieces. (1) Method for creating a measurement piece before the stress relaxation test Cut out the measurement target region from the diaper to obtain a rectangular measurement piece with a longitudinal length of 150 mm and a width length of 40 mm, where the direction corresponding to the transverse direction of the diaper is the longitudinal direction and the direction corresponding to the longitudinal direction of the diaper is the width direction. (2) Method for creating a measurement piece after the stress relaxation test (2-1) Marking Mark the measurement target region on the diaper in a rectangular shape with a transverse dimension of 150 mm and a longitudinal dimension of 40 mm of the diaper. Then, perform the following stress relaxation test. (2-2) Stress relaxation test Perform it in the same manner as the (2-2) stress relaxation test of the above <First measurement method for stress retention rate after material relaxation test>. (2-3) Taking out the measurement piece Cut out the marked part from the diaper after the stress relaxation test to obtain a measurement piece. (3) Tensile test For each measurement piece obtained by the above (1) and (2), a tensile test is performed using a tensile testing machine. Specifically, each measurement piece is fixed to the chuck of the tensile testing machine in a non-extended and non-relaxed state. At this time, for both ends in the longitudinal direction of the measurement piece, a portion 20 mm from the edge in the longitudinal direction of the measurement piece is clamped by the chuck. That is, when the length of the measurement piece in the longitudinal direction is 150 mm, the distance between the chucks is 110 mm. Then, the distance between the chucks is expanded at a speed of 300 mm / min. The stress at the time when the distance between the chucks reaches 1.4 times the initial length of the stretched portion is measured. Note that for the measurement piece after the stress relaxation test, a tensile test is performed after standing for 1 hour after the stress relaxation test. The measurement result of the measurement piece before the stress relaxation test is defined as the pre-stress P0, and the measurement result of the measurement piece after the stress relaxation test is defined as the post-stress P1. The stress retention rate after the standard relaxation test is calculated by the following formula 4. Stress retention rate after standard relaxation test = P1 / P0 ··· (Formula 4)

[0027] The stress retention rate after the standard relaxation test can also be calculated using the pre-stress P0 and the post-stress P1 measured by the following second measurement method. For example, in addition to the stress retention rate after the relaxation test of the waist stretch region W obtained by the first measurement method being greater than the stress retention rate after the relaxation test of the body circumference stretch region D, or instead of that, it is preferable that the stress retention rate after the relaxation test of the waist stretch region W obtained by the second measurement method is greater than the stress retention rate after the relaxation test of the body circumference stretch region D. The stress retention rate after the standard relaxation test calculated by the above-described first measurement method and the stress retention rate after the standard relaxation test calculated by the second measurement method are substantially the same. Here, "substantially the same" means that the magnitude relationship between the stress retention rate after the relaxation test of the waist stretch region W and the stress retention rate after the relaxation test of the body circumference stretch region D calculated by the first measurement method, and the magnitude relationship between the stress retention rate after the relaxation test of the waist stretch region W and the stress retention rate after the relaxation test of the body circumference stretch region D calculated by the second measurement method do not change.

[0028] <Second measurement method for stress retention rate after standard relaxation test> By the following method, after obtaining measurement pieces before and after the stress relaxation test from the measurement target area of the diaper, a tensile test is performed on each of the obtained measurement pieces. (1) Method for creating a measurement piece before the stress relaxation test Peel off the outer bodies 3 joined by the side seal parts S, S, unfold the diaper and spread it out flat, and cut out a rectangular measurement piece with a width direction length of 30 mm along a straight line parallel to the lateral direction Y of the diaper from the diaper. When cutting out the measurement piece, cut through the entire diaper including not only the outer body 3 but also the absorbent main body 2, the elastic member 33, and the side seal part S. (2) Method for creating a measurement piece after the stress relaxation test (2-1) Stress relaxation test Perform in the same manner as the (2-2) stress relaxation test of the above <Second measurement method of stress retention rate after material relaxation test>. (2-2) Removal of the measurement piece Perform in the same manner as the (2-3) removal of the measurement piece of the above <First measurement method of stress retention rate after standard relaxation test>. (3) Tensile test For each measurement sample obtained in the above (1) and (2), a tensile test is performed using a tensile testing machine. Specifically, each measurement sample is fixed to the chuck of the tensile testing machine in a non-extended and non-relaxed state. At this time, sandwich the chuck on the immediate inside of the both end portions in the longitudinal direction of the measurement sample, which were the portions where the side seal parts S, S were formed. Then, expand the distance between the chucks at a speed of 300 mm / min. Measure the stress at the time when the distance between the chucks reaches 71% of the length of the maximum extended state of the stretched portion. Otherwise, perform in the same manner as the (3) tensile test of the above <First measurement method of stress retention rate after standard relaxation test>.

[0029] Hereinafter, the reasons why the stress retention rates after the relaxation test are different between the waist stretchable region W and the body circumferential stretchable region D will be described in detail. When the diaper 1 is worn for a long time, the ventral outer body 3A and the dorsal outer body 3B are maintained in a state of being stretched in the lateral direction Y for a long time, so the stress of the outer bodies 3A and 3B is relaxed. In the diaper 1 of the present embodiment, as described above, both the stretchable sheet 34 which is an easy stress relaxation member and the elastic member 33 which is a difficult stress relaxation member are arranged in the waist stretchable region W and the body circumferential stretchable region D. However, the number of elastic members 33 per unit length is different between the waist stretchable region W and the body circumferential stretchable region D. Thereby, the ease of stress relaxation when the stretched state is maintained is different between the waist stretchable region W and the body circumferential stretchable region D. More specifically, since the number of elastic members 33 per unit length is smaller in the waist stretchable region W than in the body circumferential stretchable region D, the stress retention rate after the relaxation test is smaller in the waist stretchable region W than in the body circumferential stretchable region D.

[0030] In the diaper 1 of the present embodiment, the stress retention rate after the relaxation test in the waist stretchable region W is relatively small, and the stress retention rate after the relaxation test in the body circumferential stretchable region D is relatively large. Thereby, the diaper 1 of the present embodiment can suppress the displacement and is less likely to leave marks on the wearer. Hereinafter, this point will be described in detail. In conventional absorbent articles, it is known that in the waist stretch region, the abdominal circumference variation of the wearer is relatively small, and in the waist stretch region, the abdominal circumference variation of the wearer is relatively large. Therefore, in order to suppress displacement and minimize marking while suppressing displacement, the body circumference stretch region D should have a stress that suppresses displacement, while the waist stretch region W should have as little stress as possible from the viewpoint of reducing marking. In the diaper 1 of the present embodiment, by setting the post-relaxation stress retention rate of the waist stretch region W and the post-relaxation stress retention rate of the body circumference stretch region D to the above-described relationship, when the diaper 1 is worn for a long time, the stress in the body circumference stretch region D is difficult to relax, and the stress in the body circumference stretch region D is easily maintained. Therefore, the displacement of the diaper 1 can be suppressed. On the other hand, in the waist stretch region W, the stress is easily relaxed according to the body shape of the wearer while the diaper 1 is being worn. In this way, since the stress in the waist stretch region W of the diaper 1 is likely to be a stress corresponding to the body shape of the wearer, it is possible to prevent the diaper 1 from leaving a mark on the wearer. As described above, according to the diaper 1 of the present embodiment, it is possible to suppress displacement and prevent the wearer from being marked.

[0031] In the diaper 1 of the present embodiment, in the body circumference stretch region D, it is preferable that the elastic member 33, which is a stress-relaxation-resistant member, is disposed on the skin-facing side of the stretch sheet 34, which is a stress-relaxation-easy member. By doing so, when a wearer with a body size larger than the standard wears the diaper 1, the stress in the body circumference stretch region D is appropriately relaxed, excessive tightening is suppressed, and it is possible to prevent back marks from occurring.

[0032] From the perspective of further enhancing this effect, the ratio R2 / R1 of the stress retention rate R2 of the waist stretchable region W to the stress retention rate R1 of the torso stretchable region D after the standard relaxation test is preferably 0.10 or more, more preferably 0.25 or more, still more preferably 0.40 or more, preferably less than 1.0, more preferably 0.85 or less, still more preferably 0.60 or less, and preferably 0.10 or more and less than 1.00, more preferably 0.25 or more and 0.85 or less, still more preferably 0.40 or more and 0.60 or less.

[0033] From the perspective of preventing displacement, the stress retention rate R1 of the torso stretchable region D after the standard relaxation test is preferably 0.30 or more, more preferably 0.40 or more, still more preferably 0.50 or more. From the perspective of preventing excessive constriction of the wearer's torso, it is preferably 0.80 or less, more preferably 0.70 or less, still more preferably 0.60 or less. From the perspective of achieving both, it is preferably 0.30 or more and 0.80 or less, more preferably 0.40 or more and 0.70 or less, still more preferably 0.50 or more and 0.60 or less.

[0034] From the perspective of preventing displacement, the stress retention rate R2 of the waist stretchable region W after the standard relaxation test is preferably 0.10 or more, more preferably 0.2 or more, still more preferably 0.30 or more. From the perspective of preventing excessive constriction of the wearer's torso, it is preferably 0.60 or less, more preferably 0.50 or less, still more preferably 0.40 or less. From the perspective of achieving both, it is preferably 0.10 or more and 0.60 or less, more preferably 0.20 or more and 0.50 or less, still more preferably 0.30 or more and 0.40 or less.

[0035] Also, for the waist stretchable region W, it is preferable that the relaxation test post-stress retention rate (hereinafter also referred to as the "low-temperature relaxation test post-stress retention rate") R4 when stretched in an environment at a temperature below the human body temperature is greater than the standard relaxation test post-stress retention rate R1. By doing so, when the wearer wears the diaper 1, the stress is relaxed, and for example, when the diaper 1 is packaged and sold at the store, the stress is less likely to be relaxed. From the viewpoint of further enhancing this effect, for the waist stretchable region W, the ratio R4 / R1 of the low-temperature relaxation test post-stress retention rate R4 to the standard relaxation test post-stress retention rate R1 is preferably 1.50 or more, more preferably 1.75 or more, still more preferably 2.00 or more, preferably 4.00 or less, more preferably 3.75 or less, still more preferably 3.50 or less, preferably 1.50 or more and 4.00 or less, more preferably 1.75 or more and 3.75 or less, still more preferably 2.00 or more and 3.50 or less. The low-temperature relaxation test post-stress retention rate can be obtained in the same manner as the above-described <First Measurement Method of Standard Relaxation Test Post-Stress Retention Rate> (hereinafter referred to as the "First Measurement Method of Low-Temperature Relaxation Test Post-Stress Retention Rate") except that the temperature for storing the stretched diaper for 10 hours in the above-described (stress relaxation test) is changed to 23°C. Or, it can be obtained in the same manner as the above-described <Second Measurement Method of Standard Relaxation Test Post-Stress Retention Rate> (hereinafter referred to as the "Second Measurement Method of Low-Temperature Relaxation Test Post-Stress Retention Rate") except that the temperature for storing the stretched diaper for 10 hours in the above-described (stress relaxation test) is changed to 23°C. In addition to or instead of the value obtained by using the low-temperature relaxation test post-stress retention rate R4 calculated by the first measurement method of the low-temperature relaxation test post-stress retention rate satisfying the above-described numerical range, it is preferable that the value obtained by using the low-temperature relaxation test post-stress retention rate R4 calculated by the second measurement method of the low-temperature relaxation test post-stress retention rate satisfies the above-described numerical range.

[0036] The stress retention rate R4 after the low-temperature relaxation test of the waist stretch region W is preferably 0.500 or more, more preferably 0.55 or more, still more preferably 0.60 or more, from the viewpoint that the stress is less likely to relax in a state of being packaged and sold at a store, etc. From the viewpoint of not increasing the stress retention rate after the standard relaxation test, it is preferably 0.90 or less, more preferably 0.85 or less, still more preferably 0.80 or less. From the viewpoint of achieving both, it is preferably 0.500 or more and 0.90 or less, more preferably 0.55 or more and 0.85 or less, still more preferably 0.60 or more and 0.80 or less.

[0037] A preferred configuration of the ventral outer body 3A and the dorsal outer body 3B will be described. In the ventral outer body 3A, the outer layer sheet 32 is longer in the longitudinal direction X than the inner layer sheet 31 and has an extension portion 32E extending from the longitudinal end of the inner layer sheet 31. The extension portion 32E is folded back to the skin-facing surface side of the outer layer sheet 32 as shown in FIG. 4. The extension portion 32E of the outer layer sheet 32 covers the end of the absorbent body 2 in the longitudinal direction X. In the waist stretch region W, an elastic member 33 is disposed between the outer layer sheet 32 and the extension portion 32E of the outer layer sheet 32. Also, the stretch sheet 34 is also longer in the longitudinal direction X than the inner layer sheet 31 and has an extension portion 34E extending from the longitudinal end of the inner layer sheet 31. The extension portion 34E of the stretch sheet 34 is also folded back to the skin-facing surface side of the stretch sheet 34.

[0038] The dorsal outer body 3B is different from the ventral outer body 3A in that the position of the end portion 34c on the crotch portion C side of the stretch sheet 34 is different. The stretch sheet 34 in the dorsal outer body 3B has the end portion 34c on the crotch portion C side located on the crotch portion C side, more than the stretch sheet 34 in the ventral outer body 3A. In other words, in the body circumference stretch region D on the ventral side A side, the end portion 34c of the stretch sheet 34 on the crotch portion C side is located closer to the waist opening WH side than in the body circumference stretch region D on the dorsal side B side.

[0039] The circumferential expansion / contraction region D with the ventral outer body 3A and the circumferential expansion / contraction region D of the dorsal outer body 3B may or may not have the same position of the end portion 34c of the expansion / contraction sheet 34 on the thigh portion C side. When the positions of the end portions 34c of the expansion / contraction sheet 34 on the thigh portion C side are different between the circumferential expansion / contraction region D of the ventral outer body 3A and the circumferential expansion / contraction region D of the dorsal outer body 3B, either end portion 34c of the expansion / contraction sheet 34 may be located on the waist opening WH side. However, as in the present embodiment, it is preferable that the end portion 34c of the expansion / contraction sheet 34 in the circumferential expansion / contraction region D of the ventral outer body 3A is located on the waist opening WH side (see FIG. 4). By forming a larger region where the expansion / contraction sheet 34 that is easily stress-relieved is not arranged at the end portion on the thigh portion C side of the ventral outer body 3A, where the stress fluctuation is larger than that of the dorsal outer body 3B, it is possible to prevent the stress in the circumferential expansion / contraction region D of the ventral outer body 3A from being excessively reduced, and thus it is possible to effectively prevent displacement and dropping.

[0040] The ventral outer body 3A and the dorsal outer body 3B may or may not have the same number of elastic members 33 arranged in the circumferential expansion / contraction region D. However, as in the present embodiment, it is preferable that the number of the elastic members 33 is the same. By doing so, it is possible to prevent the stress in the circumferential expansion / contraction region D of the ventral outer body 3A from being excessively reduced compared to the stress in the circumferential expansion / contraction region D of the dorsal outer body 3B, and it is possible to impart the minimum stress that can prevent displacement and dropping to the circumferential expansion / contraction region D of the ventral outer body 3A.

[0041] In the circumferential stretching region D, the elastic member 33 may be disposed on the skin-facing side of the stretch sheet 34 or on the non-skin-facing side of the stretch sheet 34. However, as in the present embodiment, it is preferably disposed on the skin-facing side of the stretch sheet 34. By doing so, it becomes easier to achieve both suppression of displacement and resistance to leaving marks. Hereinafter, this point will be described in detail. The circumferential stretching region D is a part that strongly contributes to preventing the diaper 1 from slipping off. In the circumferential stretching region D, the elastic member 33 secures the stress necessary to prevent displacement, and by disposing the stretch sheet 34, the stress in the circumferential stretching region D is adjusted to a magnitude suitable for the wearer's body shape. As in the present embodiment, since the elastic member 33 is disposed on the skin-facing side of the stretch sheet 34, in the circumferential stretching region D, it becomes easier to balance the securing of stress by the elastic member 33 and the adjustment of stress by the stretch sheet 34, so it becomes easier to achieve both suppression of displacement and resistance to leaving marks.

[0042] The elastic member 33 and the stretch sheet 34 may or may not be in contact with each other. However, as in the present embodiment, it is preferably not in contact with each other. By doing so, the action of the elastic member 33 to exhibit the stress necessary to prevent displacement and the action of the stretch sheet 34 to relieve the stress of the exterior body according to the wearer's body shape and suppress excessive tightening are less likely to interfere with each other, and it becomes easier to achieve both suppression of displacement and resistance to leaving marks.

[0043] In the present embodiment, the torso expansion / contraction region D has a first region D1 located relatively closer to the waist opening WH side and a second region D2 located relatively closer to the crotch C side. The first region D1 is the region located on the waist opening WH side when the torso expansion / contraction region D is bisected in the vertical direction X, and the second region D2 is the region located on the crotch C side when the torso expansion / contraction region D is bisected in the vertical direction X. It is preferable that the stress of the elastic member 33 in the second region D2 is greater than that in the first region D1. By doing so, slippage can be effectively prevented. Hereinafter, this point will be described in detail. Since the ends on the crotch C side of the ventral exterior body 3A and the dorsal exterior body 3B move in conjunction with the movement of the wearer's legs, the stress variation in the second region D2 is greater than that in the first region D1. By making the stress T2 of the elastic member 33 in the second region D2 greater than the stress T1 of the elastic member 33 in the first region D1, it is possible to prevent the stress in the second region D2 from being excessively reduced due to stress variation during wearing, and thus prevent slippage.

[0044] The stress of the elastic member 33 referred to here is the stress at an elongation ratio of 1.4 times, and can be measured by the same method as the <Method for Measuring the Stress Retention Ratio after the Material Relaxation Test> described above.

[0045] From the viewpoint of further improving the anti-slippage effect, the ratio T2 / T1 of the stress T2 to the stress T1 is preferably 1.1 or more, more preferably 1.3 or more, still more preferably 1.5 or more, preferably 3.0 or less, more preferably 2.5 or less, still more preferably 2.0 or less, preferably 1.1 or more and 3.0 or less, more preferably 1.3 or more and 2.5 or less, still more preferably 1.5 or more and 2.0 or less.

[0046] In the present embodiment, as shown in FIG. 5, the stretch sheet 34 is a stretch sheet in which elastic filaments 43 arranged to extend in the lateral direction Y are joined between two nonwoven fabrics 41, 42. The two fiber sheets 41, 42 are stretchable in the lateral direction Y. The stretchable sheet 34 can be manufactured, for example, according to the method described in Japanese Patent Application Laid-Open No. 2009-61743. Specifically, for example, while pulling and stretching a plurality of molten elastic filaments 43 spun from a spinning nozzle at a predetermined speed, before the elastic filaments 43 solidify, the elastic filaments 43 are fused to the fiber sheets 41 and 42 so that the elastic filaments 43 are arranged in one direction without crossing each other. Then, the two sheets 41 and 42 to which the elastic filaments 43 are fused are stretched along the extending direction of the elastic filaments 43, whereby the stretchable sheet 34 can be manufactured. The entire stretchable sheet 34 has elasticity in the lateral direction Y.

[0047] In the ventral exterior body 3A or the dorsal exterior body 3B, it is preferable that the area M1 of the portion 8 where the elastic filaments 43 of the stretchable sheet 34 and the elastic member 33 overlap in the thickness direction Z of the exterior bodies 3A and 3B is small (see FIG. 6). By doing so, the region where both the stress of the elastic filaments 43 and the stress of the elastic member 33 are applied can be reduced, so that the stress of the ventral exterior body 3A or the dorsal exterior body 3B does not become excessively large, and the mark of the diaper 1 can be more effectively prevented from adhering to the wearer. From the viewpoint of making this effect more remarkable, in the plan view of the exterior bodies 3A and 3B in the maximum stretched state of the diaper 1, the ratio of the area M1 of the region where the elastic member 33 and the elastic filaments 43 overlap to the area M2 of the elastic filaments 43 is preferably 80% or less, more preferably 50% or less, and still more preferably 0%, that is, it is further preferable that the elastic member 33 and the elastic filaments 43 do not overlap each other in the thickness direction Z. The area M1 can be obtained by multiplying the total value of the lengths of the portions 8 where the elastic filaments 43 of the stretchable sheet 34 and the elastic member 33 overlap in the thickness direction Z of the exterior bodies 3A and 3B by the length in the lateral direction Y of the exterior bodies 3A and 3B (see FIG. 6). The area M2 can be obtained by multiplying the total value of the diameters of the plurality of elastic filaments 43 included in the stretchable sheet 34 by the length in the lateral direction Y of the exterior bodies 3A and 3B (see FIG. 6).

[0048] In the present embodiment, the absorbent body 2 may be provided with a pair of leak - proof cuffs 15, 15 on both left and right sides along the longitudinal direction X on the skin - facing surface of the absorbent body 2. The leak - proof cuffs 15 extend along the longitudinal direction X. As shown in FIG. 2, one end side in the transverse direction Y of the leak - proof cuff 15 is fixed to another component, for example, the surface sheet 21, and is a fixed end portion. Also, the other end side in the transverse direction Y of the leak - proof cuff 15 is a free end portion 15b that is not fixed to other components. A thread - shaped or strip - shaped elastic member (hereinafter referred to as "elastic member for forming leak - proof cuff") 16 is arranged in an extended state along the longitudinal direction X at the free end portion 15b of the leak - proof cuff 15. The leak - proof cuff 15 is such that the elastic member 16 for forming the leak - proof cuff arranged in the extended state contracts in the worn state of the diaper 1, and thereby stands up at least in the crotch portion C, and thereby prevents the lateral outflow of excreta such as urine to the outside in the transverse direction Y. In the present embodiment, both ends of the elastic member 16 for forming the leak - proof cuff in the longitudinal direction X are located inward of the longitudinal direction X than the end portion 34c on the crotch portion C side of the stretchable sheet 34.

[0049] It is preferable that the ventral outer body 3A and the dorsal outer body 3B have a stress - relaxation member non - existent region K where the stretchable sheet 34 does not exist at the end portion on the crotch portion C side in the region where the ventral outer body 3A or the dorsal outer body 3B overlaps with the leak - proof cuff 15. In the present embodiment, the stress - relaxation member non - existent region K has a strip - shaped shape extending along the transverse direction Y. By the ventral outer body 3A or the dorsal outer body 3B having the stress - relaxation member non - existent region K, even when the stress of the ventral outer body 3A or the dorsal outer body 3B is relaxed when the diaper 1 is worn, the way the absorbent body 2, particularly the leak - proof cuff 15, contacts the wearer's skin is less likely to change, and the wearing comfort can be maintained.

[0050] Also, from the same perspective, the length H1 of the non-existence region K of the easy stress relaxation member in the longitudinal direction X is preferably 1.0 mm or more, more preferably 5 mm or more, still more preferably 10 mm or more, and is preferably 30 mm or less, more preferably 20 mm or less, still more preferably 15 mm or less, and is preferably from 1 mm to 30 mm, more preferably from 5 mm to 20 mm, still more preferably from 10 mm to 15 mm.

[0051] In the present embodiment, the absorbent main body 2 is joined to the ventral exterior body 3A and the dorsal exterior body 3B. The absorbent main body 2, the ventral exterior body 3A, and the dorsal exterior body 3B are joined in the circumferential stretch region D. The method of joining the absorbent main body 2 to the ventral exterior body 3A and the dorsal exterior body 3B is not particularly limited, and for example, they may be joined by an adhesive or may be fused by heat or ultrasonic waves.

[0052] Further, the planar shape of the joint G where the absorbent main body 2 is joined to the ventral exterior body 3A or the dorsal exterior body 3B is not particularly limited. Regarding the shape of the joint G, the shape of the joint G between the ventral exterior body 3A and the absorbent main body 2 will be described as an example. In the present embodiment, as shown in FIG. 2, the joint G between the ventral exterior body 3A and the absorbent main body 2 has a first joint G1, a second joint G2, and a third joint G3. The first joint G1 is located at the end of the absorbent main body 2 in the longitudinal direction X and extends in the lateral direction Y. The second joint G2 extends from the central portion of the first joint G1 in the lateral direction Y toward the crotch portion C side. The second joint 2G2 may or may not be divided into two in the lateral direction Y. The third joint G3 extends outward in the lateral direction Y from the end of the second joint G2 on the side opposite to the first joint G1. In the present embodiment, since the joint G between the ventral exterior body 3A and the absorbent main body 2 has such a shape, even when the stress of the ventral exterior body 3A is relaxed, the way the absorbent main body 2 contacts the skin of the wearer is less likely to change, and the wearing feeling can be maintained.

[0053] FIG. 7 shows a modified example of the exterior body 3 according to the diaper 1 of the present embodiment. In the modified example shown in FIG. 7, the outer layer sheet 32 and the stretchable sheet 34, which is an easy stress relaxation member, are intermittently joined in the lateral direction Y. In other words, the outer layer sheet 32 and the stretchable sheet 34 have a plurality of joining portions 5 arranged intermittently in the lateral direction Y. The plurality of joining portions 5 form a joining portion row L arranged at intervals along the lateral direction Y, and a plurality of such joining portion rows L are provided. Each joining portion row L is arranged in parallel at intervals in the longitudinal direction X. Note that the joining portion 5 can also be formed to extend continuously in the longitudinal direction X.

[0054] In the modified example shown in FIG. 7, the outer layer sheet 32 and the inner layer sheet 31 are partially joined. Specifically, the outer layer sheet 32 and the inner layer sheet 31 are intermittently joined in the lateral direction Y. In the modified example shown in FIG. 7, the inner layer sheet 31 is joined to the outer layer sheet 32 at the joining portion 5 that joins the outer layer sheet 32 and the stretchable sheet 34.

[0055] As shown in FIG. 7, the inner layer sheet 31 forms a convex portion 61 that protrudes in a direction away from the stretchable sheet 34. The convex portion 61 is formed by the inner layer sheet 31 rising so as to be separated from the stretchable sheet 34 due to the contraction of the elastic member 33 arranged in an extended state between the outer layer sheet 32 and the inner layer sheet 31 when the ventral exterior body 3A or the dorsal exterior body 3B is in a relaxed state, causing the interval between the joining portion rows L to narrow. In the modified example shown in FIG. 7, the outer layer sheet 32 also protrudes in a direction away from the stretchable sheet 34 together with the inner layer sheet 31, but in this modified example, the outer layer sheet 32 does not necessarily have to protrude in a direction away from the stretchable sheet 34.

[0056] In the diaper 1 having the exterior body 3 shown in FIG. 7, it is possible to more effectively prevent the wearer from getting traces of the diaper 1 while preventing the stress from being excessively relaxed. Hereinafter, this point will be described in detail. In the initial state of wearing the diaper 1 (hereinafter referred to as the "initial state"), the convex portion 61 protruding toward the skin side of the wearer in the exterior body 3 is mainly in contact with the skin of the wearer. For the wearer, when the diaper 1 is small, in the initial state, the contact area between the convex portion 61 and the skin of the wearer is relatively small, so that the body temperature of the wearer is suppressed from being excessively transmitted to the stretchable sheet 34 which is an easy stress relaxation member, and the exterior body 3 is prevented from being excessively stress-relaxed by the heat caused by the body temperature of the wearer, and it is possible to suppress the stress of the exterior body 3 from being excessively lowered. On the other hand, for the wearer, when the diaper 1 is large, the contact area between the convex portion 61 and the skin of the wearer is relatively large, so that the heat caused by the body temperature of the wearer is preferentially transmitted to the stretchable sheet 34, and the stretchable sheet 34 is quickly stress-relaxed, thereby suppressing excessive tightening.

[0057] In the present embodiment, it is preferable that the waist stretchable region W has a relaxation test post-stress retention rate (hereinafter, also referred to as "post-stress retention rate in high-elongation relaxation test") R3 when stretched at a high elongation ratio is smaller than the standard relaxation test post-stress retention rate R1. By doing so, even when a wearer with a body type larger than the standard wears the diaper 1, the stress in the waist stretchable region W is more easily relaxed according to the body type of the wearer, so that it is possible to more effectively prevent the wearer from leaving marks of the diaper 1. From the viewpoint of further enhancing this effect, for the waist stretchable region W, the ratio R3 / R1 of the post-stress retention rate R3 in the high-elongation relaxation test to the standard relaxation test post-stress retention rate R1 is preferably 0 or more, more preferably 0.10 or more, still more preferably 0.25 or more, preferably 1.00 or less, more preferably 0.90 or less, still more preferably 0.75 or less, preferably 0 or more and 1.00 or less, more preferably 0.10 or more and 0.90 or less, still more preferably 0.25 or more and 0.75 or less. The post-stress retention rate in the high-elongation relaxation test can be obtained in the same manner as the <first measurement method of the standard relaxation test post-stress retention rate> described above (hereinafter, referred to as "the first measurement method of the post-stress retention rate in the high-elongation relaxation test") except that the elongation ratio in the above-described (stress relaxation test) is changed to 1.6 times. Or, it can be obtained in the same manner as the <second measurement method of the standard relaxation test post-stress retention rate> described above (hereinafter, referred to as "the second measurement method of the post-stress retention rate in the high-elongation relaxation test") except that the length in the lateral direction Y of the diaper in the above-described (stress relaxation test) is stretched until it becomes 80% of the length in the maximum elongation state. The ratio R3 / R1 of the post-stress retention rate R3 in the high-elongation relaxation test to the standard relaxation test post-stress retention rate R1 is such that the value obtained using the ratio R3 of the post-stress retention rate R3 in the high-elongation relaxation test calculated by the first measurement method of the post-stress retention rate in the high-elongation relaxation test satisfies the above-described numerical range, and in addition to or instead of this, the value obtained using the ratio R3 of the post-stress retention rate R3 in the high-elongation relaxation test calculated by the second measurement method of the post-stress retention rate in the high-elongation relaxation test satisfies the above-described numerical range.

[0058] As a means for making the stress retention rate R3 after the high-elongation relaxation test in the waist stretch region W smaller than the stress retention rate R1 after the standard relaxation test, for example, the configuration of the exterior body 3 may be made as in the modified example shown in FIG. 7. By doing so, when the waist stretch region W is stretched at a high elongation ratio, the height of the convex portion 61 becomes low, and the distance between the stretch sheet 34, which is an easy stress relaxation member, and the wearer's skin becomes close. Therefore, the exterior body 3 is likely to relax stress due to the heat caused by the wearer's body temperature. As a result, the stress retention rate R3 after the high-elongation relaxation test can be made smaller than the stress retention rate R1 after the standard relaxation test.

[0059] From the viewpoint of preventing deviation, the stress retention rate R3 after the high-elongation relaxation test in the waist stretch region W is preferably 0.05 or more, more preferably 0.100 or more, still more preferably 0.150 or more. From the viewpoint of preventing excessive tightening of the wearer's torso, it is preferably 0.350 or less, more preferably 0.300 or less, still more preferably 0.250 or less. From the viewpoint of achieving both, it is preferably 0.05 or more and 0.350 or less, more preferably 0.100 or more and 0.300 or less, still more preferably 0.150 or more and 0.250 or less.

[0060] Next, another embodiment of the present invention will be described with reference to FIGS. 8 to 11. Regarding the embodiment shown in FIGS. 8 to 12, only the differences from the embodiment shown in FIGS. 1 to 6 will be described. Points not particularly described for the embodiment shown in FIGS. 8 to 11 are the same as those in the embodiment shown in FIGS. 1 to 6, and the description of the same embodiment is applied as appropriate.

[0061] In the embodiments shown in FIGS. 8 and 9, the stretchable sheet 34 has an extending portion 34E extending from the longitudinal end of the inner layer sheet 31, but the extending portion 34E is not folded back toward the skin-facing surface side. More specifically, the end of the extending portion 34E, that is, the end of the stretchable sheet 34 on the waist opening WH side and the opening end WE of the waist opening WH are in the same position in the longitudinal direction X. Also, in the embodiments shown in FIGS. 8 and 9, the dorsal exterior body 3B does not have an extending region E. Even in the embodiments shown in FIGS. 8 and 9, the same effects as those of the embodiments shown in FIGS. 1 to 6 are achieved.

[0062] In the embodiment shown in FIG. 10, the ventral exterior body 3A and the dorsal exterior body 3B are composed of an outer layer sheet 32, an inner layer sheet 31, and a plurality of elastic members 33 arranged between the two sheets 31 and 32. In this embodiment, the outer layer sheet 32 is constituted by the stretchable sheet 34. The inner layer sheet 31 has an extending portion 31E extending from the longitudinal end of the absorbent body 2. The extending portion 31E of the inner layer sheet 31 is folded back toward the skin-facing surface side of the inner layer sheet 31 and covers the end of the absorbent body 2 in the longitudinal direction X. The outer layer sheet 32 also has an extending portion 32E extending from the longitudinal end of the absorbent body 2, and the extending portion 32E is folded back toward the skin-facing surface side of the outer layer sheet 32. In this embodiment, the stretchable sheet 34, which is the outer layer sheet 32, is in contact with the elastic member 33. Even in the embodiment shown in FIG. 10, the same effects as those of the embodiments shown in FIGS. 1 to 6 are achieved.

[0063] Also in the embodiment shown in FIG. 11, similar to the embodiment shown in FIG. 10, the ventral exterior body 3A and the dorsal exterior body 3B are each composed of an outer layer sheet 32, an inner layer sheet 31, and a plurality of elastic members 33 disposed between both sheets 31 and 32, and the outer layer sheet 32 is constituted by an elastic sheet 34. Also in the embodiment shown in FIG. 11, similar to the embodiment shown in FIG. 9, the inner layer sheet 31 has an extending portion 31E, and the extending portion 31E is folded back to the skin-facing surface side of the inner layer sheet 31 and covers the end of the absorbent body 2 in the longitudinal direction X. The outer layer sheet 32 does not extend from the longitudinal end of the absorbent body 2, and the end of the outer layer sheet 32 on the waist opening WH side and the opening end WE of the waist opening WH are in the same position in the longitudinal direction X. Also in the embodiment shown in FIG. 11, the same effects as those of the embodiments shown in FIGS. 1 to 6 are achieved.

[0064] Next, matters common to the above-described embodiments will be described. Examples of the stress relaxation member include, in addition to the elastic sheet 34 described above, a thermoplastic resin film having elasticity, and the like. Examples of the thermoplastic resin film having elasticity include a urethane film, and the like. Among these, it is preferable to use the elastic sheet 34 as the stress relaxation member from the viewpoint of easy stress relaxation.

[0065] The two fiber sheets 41 and 42 constituting the elastic sheet 34 used as the stress relaxation member may each be a nonwoven fabric of short fibers. Examples of the nonwoven fabric include an air-through nonwoven fabric, a heat-rolled nonwoven fabric, a spunlace nonwoven fabric, a spunbond nonwoven fabric, a meltblown nonwoven fabric, and the like. The two sheets 41 and 42 may be of the same type or different types from each other. The elastic filament 43 that constitutes the telescopic sheet 34 is preferably a thermoplastic elastomer resin represented by an A-B-A triblock copolymer having two types of polymer blocks, block A and block B. The A-B-A triblock copolymer is composed of block A and block B. The A-B-A triblock copolymer can be a copolymer selected from the group consisting of the substances of block A and the group consisting of the substances of block B, which will be described in detail. The elastic filament 43 may be one type of A-B-A triblock copolymer or two or more types of A-B-A triblock copolymers.

[0066] In the A-B-A triblock copolymer, block A is a hard segment. In the A-B-A triblock copolymer, the chains of block A aggregate with each other to form a hard phase. Since the glass transition temperature (Tg) of block A is 25°C or higher, for example, at about room temperature, it forms a hard phase and acts as a physical crosslinking point. Also, above the glass transition temperature (Tg), block A melts and has fluidity, so processing and molding become easy.

[0067] The A-B-A triblock copolymer has a glass transition temperature (Tg) of block A of 25°C or higher, preferably 60°C or higher, more preferably 70°C or higher, and also preferably 100°C or lower. Further, the glass transition temperature (Tg) of block B is less than 25°C, preferably 0°C or lower, more preferably -30°C or lower, and also preferably -70°C or higher. The glass transition temperature (Tg) in this specification can be measured by thermomechanical analysis (TMA), differential scanning calorimetry (DSC), differential thermal analysis (DTA), or dynamic viscoelasticity measurement. Specifically, for example, it can be determined using a commercially available viscoelasticity measurement device, the Rheovibron DDV-GP series (A&D Company, Limited). The measurement conditions for the glass transition temperature (Tg) are as follows: when the measurement sample is a film sheet, a sheet with a thickness of 2 mm, a width of 5 mm, and a length of 2 cm is heated in a nitrogen atmosphere at 2 Hz torsion mode from -75°C at a heating rate of 5°C / min for measurement. Also, when the sample is mounted in a product such as a diaper, first, only the target sample is peeled off and taken out from the product. The taken-out sample is dissolved in a toluene solvent. If solids are present at this time, filtration is performed, and the filtered solvent is evaporated to obtain a sample in film form. The sample thus obtained can be evaluated by selecting from the above-described measurement methods.

[0068] In the A-B-A triblock copolymer, the weight average molecular weight of block A is preferably 1900 or higher, more preferably 4000 or higher, and still more preferably 6000 or higher. Also, the weight average molecular weight of block A is preferably 12000 or lower, more preferably 10000 or lower, and still more preferably 8000 or lower. When the weight average molecular weight of block A is within this range, it is possible to eliminate rubber marks caused by excessive tightening without the stress relaxation member slipping off or damaging the appearance due to the body temperature of the wearer.

[0069] In an A-B-A triblock copolymer, block A preferably mainly consists of a vinyl aromatic polymer. Here, "mainly consists of" means that the content of the vinyl aromatic polymer in block A is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 100% by mass based on all the structural units of block A. The structure contained in the sample can be specified by using nuclear magnetic resonance (NMR) or infrared spectroscopy (IR), and its ratio can be determined from the peak integration value of NMR. When measuring a sample mounted in a product, the sample obtained by the above-mentioned means can be dissolved in a toluene solvent for NMR measurement and evaluated in its original form for IR measurement.

[0070] Examples of the vinyl aromatic compound constituting block A of the A-B-A triblock copolymer include styrene, p-methylstyrene, m-methylstyrene, p-tert-butylstyrene, α-methylstyrene, chloromethylstyrene, p-tert-butoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, vinyltoluene, 1-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, etc. Block A of the A-B-A triblock copolymer may be composed of these vinyl aromatic compounds alone or composed of two or more of them. Among these vinyl aromatic compounds, it is more preferable to use styrene in terms of ease of polymerization and versatility.

[0071] Also, in the A-B-A triblock copolymer, block B is a soft segment. In the A-B-A triblock copolymer, block B behaves as a soft phase at about room temperature, for example, and is a part that exhibits rubber elasticity.

[0072] In the A-B-A triblock copolymer, the weight-average molecular weight of block B is preferably 10,000 or more, more preferably 15,000 or more, still more preferably 20,000 or more, and particularly preferably 30,000 or more. Also, the weight-average molecular weight of block B is preferably 90,000 or less, more preferably 70,000 or less, still more preferably 50,000 or less, and particularly preferably 40,000 or less. When the weight-average molecular weight of block B is within this range, it is possible to eliminate rubber marks caused by excessive tightening without the stress relaxation member slipping off or damaging the appearance due to the body temperature of the wearer.

[0073] Block B of the A-B-A triblock copolymer preferably mainly consists of polyolefin. Here, "mainly consists of" means that the content of polyolefin in block B is preferably 90% by mass or more, more preferably 95% by mass or more, based on all the structural units of block B.

[0074] Examples of the olefin constituting block B of the A-B-A triblock copolymer include ethylene, propylene, butylene, 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, phenylbutadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, and the like. Block B may be composed of these olefins alone or of two or more of them. Also, block B may be hydrogenated so that part or all of the double bonds are saturated.

[0075] Examples of the A-B-A triblock copolymer include, specifically, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS) which is a hydrogenated product of SBS, styrene-ethylene-propylene-styrene block copolymer (SEPS) which is a hydrogenated product of SIS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), and the like. Among these, SEBS, SEPS, and SEEPS are preferable in terms of thermal stability and weather resistance.

[0076] The weight average molecular weight of the A-B-A triblock copolymer is preferably 30,000 or more, more preferably 35,000 or more, still more preferably 40,000 or more, and particularly preferably 45,000 or more. Also, the weight average molecular weight of the A-B-A triblock copolymer is preferably 110,000 or less, more preferably 90,000 or less, still more preferably 70,000 or less, and particularly preferably 60,000 or less. When the weight average molecular weight of the A-B-A triblock copolymer is within this range, it becomes possible to eliminate rubber marks caused by excessive tightening without the stress relaxation member slipping off or damaging the appearance due to the body temperature of the wearer.

[0077] In this specification, the weight-average molecular weight of the A-B-A triblock copolymer is measured by the GPC method. The weight-average molecular weight of block A and the weight-average molecular weight of block B can be obtained from the ratio determined from the identification of the structural formula and the NMR peak integration value using nuclear magnetic resonance (NMR) separately after measuring the weight-average molecular weight of the entire A-B-A triblock copolymer, and the obtained ratio and the weight-average molecular weight of the whole. The measurement conditions of the GPC method are as follows: column: TSKgel G-2000H, column temperature: 40 °C, mobile phase: tetrahydrofuran (THF), flow rate: 1.0 mL / min, sample concentration: 10 mg / 5 mL-THF, injection volume: 500 μL, and the weight-average molecular weight is a value converted by polystyrene. For the analytical sample, as a pretreatment, 10 mg of the sample is dissolved in 5 mL of THF (tetrahydrofuran) at room temperature for 10 minutes and then filtered through a sintered filter with a pore size of 0.45 μm.

[0078] In this embodiment, the A-B-A triblock copolymer can be synthesized, for example, by the following steps. First, a vinyl aromatic compound and a conjugated diene compound are added to a hydrocarbon solvent such as cyclohexane in an appropriate order, and anionic polymerization is carried out using an organolithium compound, sodium metal, etc. as an initiator to obtain a copolymer having a double bond based on the conjugated diene.

[0079] Next, hydrogen is added to the double bond based on the conjugated diene of this copolymer to obtain the target A-B-A triblock copolymer. The hydrogenation rate of the double bond based on the conjugated diene is preferably 80% or more, particularly 90% or more, from the viewpoints of heat resistance and weather resistance. The hydrogenation reaction can be carried out using a noble metal-based catalyst such as platinum or palladium, an organic nickel compound, an organic cobalt compound, or a composite catalyst of these compounds and other organometallic compounds. The hydrogenation rate is calculated by the iodine value measurement method.

[0080] In addition, commercially available products can also be used as the A-B-A triblock copolymer. Examples of commercially available products preferably used in this embodiment as the A-B-A triblock copolymer include, for example, the product name "Clayton" of Clayton Polymer Co., Ltd., the product names "Tuftec" and "Tufprene" of Asahi Kasei Chemicals Corporation, the product names "Septon" and "Hybrar" series of Kuraray Co., Ltd., and the like.

[0081] The thermoplastic elastomer resin may contain other resins other than the A-B-A triblock copolymer. As the other resins, for example, rubber, or thermoplastic elastomers such as polyolefin-based elastomers, polyester-based elastomers, polyurethane-based elastomers, etc. can be used. These can be used alone or in combination of two or more. Further, the thermoplastic elastomer resin composition may contain a plasticizer, and as the plasticizer, paraffinic oil, paraffinic wax, naphthenic oil, ethylene-α-olefin oligomer, low molecular weight polyethylene, etc. can be used. These can be used alone or in combination of two or more.

[0082] As the elastic member 33 used as the stress relaxation difficult member, for example, synthetic rubbers such as styrene-butadiene, butadiene, isoprene, neoprene, natural rubber, EVA, stretchable polyolefin, polyurethane, etc. formed into a filamentous (such as thread rubber) or cord-like (such as flat rubber) can be preferably used. Among these, from the viewpoint of being difficult to relax stress, synthetic rubbers such as styrene-butadiene, butadiene, isoprene, neoprene, etc. are particularly preferable. The cross-section of the elastic member 33 may be rectangular, square, circular, elliptical, polygonal, etc.

[0083] As the top sheet, a sheet having liquid permeability, such as a non-woven fabric or a perforated film, can be used. The top sheet may have an uneven shape on the side facing the skin. For example, a plurality of convex portions can be formed in a scattered pattern on the side of the top sheet facing the skin. Alternatively, ridges and grooves extending in one direction can be alternately formed on the side of the top sheet facing the skin. For such purposes, the top sheet can also be formed using two or more non-woven fabrics.

[0084] On the other hand, as the back sheet, for example, a liquid-impermeable film, a spunbond-meltblown-spunbond laminated non-woven fabric, etc. can be used. A plurality of micropores can be provided in the liquid-impermeable film, and the film can be given water vapor permeability. For the purpose of further improving the feel of the absorbent article against the skin, etc., a sheet with a good texture such as a non-woven fabric can be laminated on the outer surface of the back sheet.

[0085] The absorber includes an absorbent core. The absorbent core is composed of, for example, a laminate of hydrophilic fibers such as pulp and other cellulose, a mixed laminate of the hydrophilic fibers and an absorbent polymer, a deposit of an absorbent polymer, a laminated structure in which an absorbent polymer is supported between two absorbent sheets, etc. The absorbent core may be covered with a core wrap sheet that is liquid-permeable at least on the side facing the skin, or the entire surface including the side facing the skin and the side not facing the skin may be covered with a core wrap sheet. As the core wrap sheet, for example, thin paper made of hydrophilic fibers, a non-woven fabric having liquid permeability, etc. can be used.

[0086] As described above, the present invention has been described based on its embodiments, but the present invention can be appropriately modified without being limited to the above embodiments. For example, in each of the above-described embodiments, the outer wrapper 3 is divided into a ventral outer wrapper 3A and a dorsal outer wrapper 3B, but the outer wrapper 3 may have a continuous shape covering the ventral part A, the crotch part C, and the dorsal part B. Also, all parts that are unique to only one of the above-described embodiments can be appropriately used with each other. Regarding the above-described embodiments, the present invention further discloses the following absorbent articles.

[0087] <1> It includes an absorbent body and an exterior body disposed on the non-skin-facing surface side of the absorbent body, It has a ventral part disposed on the ventral side of the wearer, a dorsal part disposed on the dorsal side of the wearer, and a crotch part located between the ventral part and the dorsal part, and has a longitudinal direction corresponding to the direction extending from the ventral part through the crotch part to the dorsal part and a transverse direction orthogonal to the longitudinal direction. A pair of side seal parts, a waist opening, and a pair of leg openings are formed by joining both side parts of the ventral part and both side parts of the dorsal part. It is a pant-type absorbent article, The exterior body includes, as a stretchable member, an easy stress relaxation member and a difficult stress relaxation member that is less stress-relaxing than the easy stress relaxation member, and has a waist stretch region that is located on the opening end side of the waist opening rather than the edge of the absorbent body in the longitudinal direction and stretches in the transverse direction, and a body circumference stretch region that is located on the crotch part side rather than the edge of the absorbent body in the longitudinal direction, In the waist stretch region, the number of the difficult stress relaxation members per unit length in the longitudinal direction is less than that in the body circumference stretch region, The absorbent article, wherein the waist stretch region has an elongation magnification of 1.4 times and a post-stress retention rate after a standard relaxation test after being left for 10 hours at a temperature of 40 °C is smaller than that of the body circumference stretch region. <2> The absorbent article according to <1>, wherein the ratio of the post-stress retention rate of the easy stress relaxation member to the post-stress retention rate of the difficult stress relaxation member after a material relaxation test is 0.10 or more and less than 1.00, preferably 0.20 or more and 0.80 or less, more preferably 0.30 or more and 0.50 or less. <3> The absorbent article according to <1> or <2>, wherein the post-stress retention rate of the easy stress relaxation member after a material relaxation test is 0.10 or more and 0.70 or less, preferably 0.20 or more and 0.60 or less, more preferably 0.30 or more and 0.50 or less. <4> The stress relaxation rate after the material relaxation test of the stress relaxation resistant member is 0.50 or more, preferably 0.60 or more, preferably 0.70 or more, and preferably less than 1.0. The absorbent article according to any one of <1> to <3> above. <5> The stress relaxation rate after the standard relaxation test of the waist stretch region with respect to the stress relaxation rate after the standard relaxation test of the body circumferential stretch region is 0.10 or more and less than 1.00, preferably 0.25 or more and 0.85 or less, more preferably 0.40 or more and 0.60 or less. The absorbent article according to any one of <1> to <4> above. <6> The stress relaxation rate after the standard relaxation test of the body circumferential stretch region is 0.30 or more and 0.80 or less, preferably 0.40 or more and 0.70 or less, more preferably 0.50 or more and 0.60 or less. The absorbent article according to any one of <1> to <5> above. <7> The stress relaxation rate after the standard relaxation test of the waist stretch region is 0.10 or more and 0.60 or less, preferably 0.20 or more and 0.50 or less, more preferably 0.30 or more and 0.40 or less. The absorbent article according to any one of <1> to <6> above. <8> In the body circumferential stretch region, the stress relaxation resistant member is disposed on the skin-facing surface side of the stress relaxation easy member. The absorbent article according to any one of <1> to <7> above. <9> The stress relaxation easy member and the stress relaxation resistant member are not in direct contact. The absorbent article according to any one of <1> to <8> above. <10> The waist stretch region has an elongation magnification of 1.6 times, and the stress relaxation rate after the high elongation relaxation test after leaving it at 40 ° C for 10 hours is smaller than the stress relaxation rate after the standard relaxation test. The absorbent article according to any one of <1> to <9> above. <11> The ratio of the stress relaxation rate after the high elongation relaxation test to the stress relaxation rate after the standard relaxation test in the waist stretch region is 0 or more and 1.00 or less, preferably 0.10 or more and 0.90 or less, more preferably 0.25 or more and 0.75 or less. The absorbent article according to <10> above. <12> The stress retention rate after the high-elongation relaxation test of the waist stretchable region is 0.05 or more and 0.350 or less, preferably 0.100 or more and 0.300 or less, more preferably 0.150 or more and 0.250 or less. The absorbent article according to <10> or <11>. <13> The waist stretchable region has an elongation magnification of 1.4 times, and the stress retention rate after the low-temperature relaxation test after leaving it at 23°C for 10 hours is greater than the stress retention rate after the standard relaxation test. The absorbent article according to any one of <1> to <12>. <14> The ratio of the stress retention rate after the low-temperature relaxation test to the stress retention rate after the relaxation test in the waist stretchable region is 1.50 or more and 4.00 or less, preferably 1.75 or more and 3.75 or less, more preferably 2.00 or more and 3.50 or less. The absorbent article according to <13>. <15> The stress retention rate after the low-temperature relaxation test of the waist stretchable region is 0.500 or more and 0.90 or less, preferably 0.55 or more and 0.85 or less, more preferably 0.60 or more and 0.80 or less. The absorbent article according to <13> or <14>. <16> The easy stress relaxation member is a stretchable sheet in which elastic filaments arranged to extend in the transverse direction are joined between two nonwoven fabrics. In a plan view of the outer package in the maximum elongation state of the absorbent article, the ratio of the area of the region where the difficult stress relaxation member and the elastic filament overlap to the area of the elastic filament is 80% or less. The absorbent article according to any one of <1> to <15>. <17> The outer package includes a ventral outer package disposed on the ventral side and a dorsal outer package disposed on the dorsal side. The absorbent body is fixed across between the ventral outer package and the dorsal outer package. The absorbent body has a leak-proof cuff extending along the longitudinal direction. The ventral outer body and the dorsal outer body have a stress relaxation member non-existence region where the stress relaxation member does not exist at an end portion on the crotch side in a region where the ventral outer body or the dorsal outer body overlaps with the leak-proof cuff. The absorbent article according to any one of <1> to <16> above. <18> The absorbent article according to <17> above, wherein a longitudinal length of the stress relaxation member non-existence region is 1 mm or more and 30 mm or less, preferably 5 mm or more and 20 mm or less, and more preferably 10 mm or more and 15 mm or less. <19> The outer body includes a ventral outer body disposed on the ventral side and a dorsal outer body disposed on the dorsal side. The absorbent main body is fixed across between the ventral outer body and the dorsal outer body. The ventral outer body and the dorsal outer body are joined by a joining portion with the absorbent main body. The absorbent article according to any one of <1> to <18> above, wherein the joining portion has a first joining portion extending in the lateral direction, a second joining portion extending from a central portion in the lateral direction of the first joining portion toward the crotch side, and a third joining portion extending outward in the lateral direction from an end portion of the second joining portion on the crotch side. <20> The number of stress relaxation members disposed in the torso stretch region on the ventral side and the number of stress relaxation members disposed in the torso stretch region on the dorsal side are the same. The absorbent article according to any one of <1> to <19> above, wherein an end portion of the stress relaxation member on the crotch side in the torso stretch region on the ventral side is located closer to the waist opening side than the torso stretch region on the dorsal side. <21> The torso stretch region has a first region located relatively closer to the waist opening side and a second region located relatively closer to the crotch side. The absorbent article according to any one of <1> to <20> above, wherein the stress of the stress relaxation member is greater in the second region than in the first region. <22> The ratio of the stress of the stress relaxation difficult member in the second region to the stress of the stress relaxation difficult member in the first region is 1.1 or more and 3.0 or less, preferably 1.3 or more and 2.5 or less, more preferably 1.5 or more and 2.0 or less, The absorbent article according to <21>. <23> The exterior body has an outer layer sheet disposed on the skin-facing side of the stress relaxation easy member, and an inner layer sheet disposed on the skin-facing side of the outer layer sheet. The outer layer sheet and the stress relaxation easy member are intermittently joined in the lateral direction. The outer layer sheet and the inner layer sheet are partially joined. The inner layer sheet forms a convex portion protruding in a direction away from the stress relaxation easy member, The absorbent article according to any one of <1> to <22>.

Example

[0088] Hereinafter, the present invention will be described in more detail using examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “mass%”.

[0089] 〔Example 1〕 A pant-type disposable diaper having substantially the same basic configuration as the diaper 1 shown in FIG. 2 was produced. Specifically, a commercially available pant-type disposable diaper (manufactured by Kao Corporation, trade name “Merries (registered trademark) Pants L size”) was prepared, the stretch sheet of the prepared diaper was changed to another stretch sheet, and the elastic member of the diaper was changed to another elastic member, which was designated as Example 1. In Example 1, a stretch sheet 34 was manufactured according to the method described in JP-A-2009-61743, and this was used as a stress relaxation easy member. As the elastic filament 43 constituting the stress relaxation easy member, SEPS was used as an A-B-A triblock copolymer. The molecular weight of the A-B-A triblock copolymer, the molecular weight of block A, and the molecular weight of block B were as shown in Table 1. In Example 1, the elastic member 33 shown in Table 1 was used and was used as the stress relaxation resistant member. The number of stress relaxation resistant members per unit length in the waist stretch region of the prepared diaper and the number of stress relaxation resistant members per unit length in the body circumference stretch region of the diaper were made as shown in Table 1.

[0090] [Example 2] In Example 1, the molecular weight of the A-B-A triblock copolymer, the molecular weight of block A, and the molecular weight of block B in the elastic filament 43 constituting the stress relaxation member were changed as shown in Table 1. Otherwise, a pant-type disposable diaper having the same configuration as in Example 1 was produced and used as Example 2.

[0091] [Comparative Example 1] A pant-type disposable diaper having the same configuration as in Example 1 was produced as Comparative Example 1, except that the number of stress relaxation resistant members per unit length in the waist stretch region of the prepared diaper and the number of stress relaxation resistant members per unit length in the body circumference stretch region of the diaper were changed as shown in Table 1.

[0092] [Comparative Example 2] In Example 1, the molecular weight of the A-B-A triblock copolymer, the molecular weight of block A, and the molecular weight of block B in the elastic filament 43 constituting the stress relaxation member were changed as shown in Table 1. Otherwise, a pant-type disposable diaper having the same configuration as in Example 1 was produced and used as Comparative Example 2.

[0093] <Measurement of the number of elastic members per unit length> For the pant-type disposable diapers of Examples 1 and 2 and Comparative Examples 1 and 2, the number of elastic members per unit length in the waist stretch region and the number of elastic members per unit length in the body circumference stretch region were measured according to the above method.

[0094] <Measurement of the stress retention rate after the standard relaxation test> For the pant-type disposable diapers of Examples 1 and 2 and Comparative Examples 1 and 2, in accordance with the second measurement method of stress retention rate after the standard relaxation test, the stress retention rate R2 after the standard relaxation test in the waist stretch region and the stress retention rate R1 after the standard relaxation test in the hip circumference stretch region were measured. The stress retention rate R2 after the standard relaxation test in the waist stretch region, the stress retention rate R1 after the standard relaxation test in the hip circumference stretch region, and R2 / R1 are shown in Table 1.

[0095] <Evaluation of the resistance of diapers to slipping off> The pant-type disposable diapers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were worn on a baby dynamic model equivalent to a 1- to 2-year-old child. After making this model perform an operation of moving the legs up and down simultaneously at a speed of 15 times per minute for 15 minutes, the resistance of the pant-type disposable diapers to slipping off was evaluated in accordance with the following evaluation criteria. A: The amount of slippage is less than 15 mm. B: The amount of slippage is 15 mm or more and less than 25 mm. C: The amount of slippage is 25 mm or more.

[0096] <Evaluation of the difficulty of diaper marks on the wearer> The pant-type disposable diapers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were worn on 1- to 2-year-old children for 4 to 10 hours (used as usual), and the state of diaper marks was observed. The difficulty of diaper marks on the wearer caused by wearing the pant-type disposable diapers was evaluated in accordance with the following evaluation criteria. A: The level where almost no diaper marks can be seen. B: The level where even if there are diaper marks, it doesn't matter. C: The level where the diaper marks are clearly attached and noticeable.

[0097]

Table 1

[0098] As is clear from the results shown in Table 1, in the pant-type disposable diapers obtained in Examples 1 and 2, it can be seen that the number of stress relaxation members per unit length in the waist stretch region is smaller than that in the body circumference stretch region. Due to this, the waist stretch region has a smaller stress retention rate after the standard relaxation test than the body circumference stretch region, and the pant-type disposable diapers obtained in Examples 1 and 2 have less displacement and are less likely to leave marks on the wearer compared to the pant-type disposable diapers obtained in Comparative Examples 1 and 2. Further, in the pant-type disposable diapers obtained in Examples 1 and 2, it can be seen that the stress retention rate in the waist stretch region is smaller than that in the body circumference stretch region after the standard relaxation test. From this also, the pant-type disposable diapers obtained in Examples 1 and 2 have less displacement and are less likely to leave marks on the wearer compared to the pant-type disposable diapers obtained in Comparative Examples 1 and 2.

Explanation of Signs

[0099] 1 Pant-type disposable diaper 2 Absorbent main body 21 Surface sheet 22 Back sheet 23 Absorbent body 3 Outer cover 3A Abdominal side outer cover 3B Dorsal side outer cover 31 Inner layer sheet 32 Outer layer sheet 33 Stress relaxation member (elastic member) 34 Easy stress relaxation member (stretch sheet) 41,42 Fiber sheet 43 Elastic filament W Waist stretch region D Body circumference stretch region

Claims

1. An absorbent article comprising an absorbent body and an outer wrapper disposed on the non-skin-facing side of the absorbent body, having a ventral part disposed on the ventral side of the wearer, a dorsal part disposed on the dorsal side of the wearer, and a crotch part located between the ventral part and the dorsal part, having a longitudinal direction corresponding to the direction extending from the ventral part through the crotch part to the dorsal part and a transverse direction orthogonal to the longitudinal direction, and a pair of side seal parts, a waist opening, and a pair of leg openings being formed by joining both side parts of the ventral part and both side parts of the dorsal part, which is a pant-type absorbent article, wherein the outer wrapper includes, as a stretch member, an easy stress relaxation member and a difficult stress relaxation member that is less stress-relaxing than the easy stress relaxation member, and has a waist stretch region located on the opening end side of the waist opening rather than the edge of the absorbent body in the longitudinal direction and stretching in the transverse direction, and a body circumference stretch region located on the crotch part side rather than the edge of the absorbent body in the longitudinal direction, wherein the number of the difficult stress relaxation members per unit length in the longitudinal direction of the waist stretch region is smaller than that of the body circumference stretch region, wherein the waist stretch region has an elongation magnification of 1.4 times and a standard relaxation test post-stress retention rate after being left for 10 hours at a temperature of 40°C is smaller than that of the body circumference stretch region, wherein, in the body circumference stretch region, the difficult stress relaxation member is disposed on the skin-facing side of the easy stress relaxation member, an absorbent article.

2. An absorbent article comprising an absorbent body and an outer wrapper disposed on the non-skin-facing side of the absorbent body, having a ventral part disposed on the ventral side of the wearer, a dorsal part disposed on the dorsal side of the wearer, and a crotch part located between the ventral part and the dorsal part, having a longitudinal direction corresponding to the direction extending from the ventral part through the crotch part to the dorsal part and a transverse direction orthogonal to the longitudinal direction, and a pair of side seal parts, a waist opening, and a pair of leg openings being formed by joining both side parts of the ventral part and both side parts of the dorsal part, which is a pant-type absorbent article, wherein the outer wrapper includes, as a stretch member, an easy stress relaxation member and a difficult stress relaxation member that is less stress-relaxing than the easy stress relaxation member, and has a waist stretch region located on the opening end side of the waist opening rather than the edge of the absorbent body in the longitudinal direction and stretching in the transverse direction, and a body circumference stretch region located on the crotch part side rather than the edge of the absorbent body in the longitudinal direction, The waist stretchable region has a smaller number of the stress relaxation difficult members per unit length in the longitudinal direction than the body circumference stretchable region. The waist stretchable region is stretched in the lateral direction until it reaches a length of 71% of the length of the pant-type absorbent article in the maximum stretched state, and the stress retention rate after the standard relaxation test after leaving it at a temperature of 40°C for 10 hours is smaller than that of the body circumference stretchable region. In the body circumference stretchable region, the stress relaxation difficult member is disposed on the skin-facing side of the stress relaxation easy member, the absorbent article.

3. The absorbent article according to claim 1 or 2, wherein the stress relaxation easy member and the stress relaxation difficult member are not in direct contact with each other.

4. The waist stretchable region has an elongation magnification of 1.6 times, and the stress retention rate after the high elongation relaxation test after leaving it at a temperature of 40°C for 10 hours is smaller than the stress retention rate after the standard relaxation test, the absorbent article according to any one of claims 1 to 3.

5. The waist stretchable region has an elongation magnification of 1.4 times, and the stress retention rate after the low temperature relaxation test after leaving it at a temperature of 23°C for 10 hours is larger than the stress retention rate after the standard relaxation test, the absorbent article according to any one of claims 1 to 4.

6. The stress relaxation easy member is a stretchable sheet in which elastic filaments arranged to extend in the lateral direction are joined between two nonwoven fabrics. In a plan view of the outer wrapper in the maximum stretched state of the absorbent article, the ratio of the area of the region where the stress relaxation difficult member and the elastic filament overlap to the area of the elastic filament is 80% or less, the absorbent article according to any one of claims 1 to 5.

7. The outer wrapper includes a ventral outer wrapper disposed on the ventral side and a dorsal outer wrapper disposed on the dorsal side. The absorbent body is fixed so as to span between the ventral outer wrapper and the dorsal outer wrapper. The absorbent body has a leak-proof cuff extending along the longitudinal direction. The ventral outer wrapper and the dorsal outer wrapper have a stress relaxation easy member non-existence region where the stress relaxation easy member does not exist at an end portion on the crotch side in a region where the ventral outer wrapper or the dorsal outer wrapper overlaps with the leak-proof cuff, the absorbent article according to any one of claims 1 to 6.

8. The longitudinal length of the stress relaxation easy member non-existence region is 1 mm or more and 30 mm or less, the absorbent article according to claim 7.

9. The outer package includes a ventral outer package disposed on the ventral side and a dorsal outer package disposed on the dorsal side. The absorbent body is fixed across between the ventral outer package and the dorsal outer package. The ventral outer package and the dorsal outer package are joined to the absorbent body by a joining portion. The absorbent article according to any one of claims 1 to 8, wherein the joining portion has a first joining portion extending in the lateral direction, a second joining portion extending from the central portion in the lateral direction of the first joining portion toward the crotch side, and a third joining portion extending outward in the lateral direction from the end of the second joining portion on the crotch side.

10. The number of stress relaxation members arranged in the circumferential stretch region on the ventral side and the circumferential stretch region on the dorsal side is the same. The absorbent article according to any one of claims 1 to 9, wherein in the circumferential stretch region on the ventral side, the end of the stress relaxation member on the crotch side is located closer to the waist opening side than in the circumferential stretch region on the dorsal side.

11. The circumferential stretch region has a first region located relatively closer to the waist opening side and a second region located relatively closer to the crotch side. The absorbent article according to any one of claims 1 to 10, wherein the stress of the stress relaxation member is greater in the second region than in the first region.

12. The outer package has an outer layer sheet disposed on the skin-facing side of the stress relaxation member and an inner layer sheet disposed on the skin-facing side of the outer layer sheet. The outer layer sheet and the stress relaxation member are intermittently joined in the lateral direction. The outer layer sheet and the inner layer sheet are partially joined. The absorbent article according to any one of claims 1 to 11, wherein the inner layer sheet forms a convex portion protruding in a direction away from the stress relaxation member.

13. The absorbent article according to any one of claims 1 to 12, wherein the waist stretch region is stretched in the lateral direction until it reaches 80% of the length in the maximum stretched state of the pant-type absorbent article, and the stress retention rate after the high elongation relaxation test after being left at a temperature of 40 ° C for 10 hours is smaller than the standard relaxation test stress retention rate.

14. The absorbent article according to any one of claims 1 to 13, wherein the waist elastic region is stretched in the lateral direction until it reaches a length of 71% of the length of the pant-type absorbent article in the maximum stretched state, and the stress retention rate after the low-temperature relaxation test after leaving it at a temperature of 23°C for 10 hours is greater than the stress retention rate after the standard relaxation test.

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