CN112004507A - Absorbent article - Google Patents

Abstract

The absorbent article has: an absorbent main body (10) provided with an absorbent core (11A); and a pair of waist parts (20). The waist body part (20) is provided with a skin side sheet part (221) positioned closest to the skin and a plurality of elastic threads (23) capable of stretching in the transverse direction. In the waist part (20), the bending rigidity of the skin side panel part (221) measured by the KES method is 0.0096 N.m²/m×10^‑4Thereafter, the inner sheet portion (21) is disposed between the skin-side sheet portion (221) and the elastic thread (23) in the thickness direction of the waistline portion (20) and is located in the longitudinal directionThe waist side of the absorbent main body (10). The bending rigidity of the inner sheet portion (21) measured by the KES method is greater than the bending rigidity of the skin-side sheet portion (221).

Description

absorbent articles

technical field

The present invention relates to an absorbent article.

Background technique

Patent Document 1 discloses an absorbent article including an absorptive main body (a main body portion) including a liquid-permeable front sheet, a liquid-impermeable surface sheet, and an exterior sheet covering the back side of the absorptive main body. The back side panel and the absorber between the front panel and the back side panel. Furthermore, Patent Document 1 finds that the flexibility of the outermost nonwoven fabric of the exterior sheet significantly affects the flexibility of the entire absorbent article, and discloses that the outermost nonwoven fabric is a soft nonwoven having a degree of curvature of 3.8 gf·cm/cm or less cloth.

In addition, Patent Document 1 describes that, similar to the outermost nonwoven fabric, it is desirable that all the nonwoven fabrics constituting the exterior sheet, that is, the front and rear pressure sheets covering the front and rear end portions of the absorptive main body, and the outermost nonwoven fabric The upper layer of non-woven fabric with elastic threads sandwiched in the middle is made of soft non-woven fabric. Patent Document 1 also discloses that the front and rear pressure sheets are formed by extending the inner surface folded portion of the soft outermost nonwoven fabric until the portion overlaps the front and rear end portions of the absorbent main body.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2010-131167

SUMMARY OF THE INVENTION

Invention to solve problem

The problem to be solved by the present invention is at least one of the following first problem and second problem.

The first problem is that, in the above case, the material arranged on the skin side with respect to the elastic threads is only a soft nonwoven fabric. In this case, the linear load of the elastic thread is less likely to be absorbed and relieved by the nonwoven fabric on the skin side, and the elastic thread is fixed to the wearer's skin while the nonwoven fabric adheres around the elastic thread. Therefore, linear loads of elastic threads may be exerted on the wearer's skin, and traces of the elastic threads may remain on the wearer's skin. In particular, in many cases, the wearer's abdomen protrudes, and line marks may appear on the wearer's abdomen.

Accordingly, it is an object of the present invention to provide an absorbent article that is less likely to create line marks on the waist of the wearer.

The second problem is that, in the above-mentioned case, the material arranged on the skin side with respect to the waist side end portion (front and rear end portion) of the absorbent body is only a soft nonwoven fabric. In the waist side end portion of the absorbent body, a plurality of materials are laminated to each other and an adhesive is applied. Therefore, the waist side edge of the absorptive main body is hard, and the soft nonwoven fabric is difficult to absorb and relax the hardness of the waist side edge of the absorptive main body (that is, between the part having the absorptive main body and the part not having the absorptive main body). the hardness of the edges in the steps). Therefore, there is a risk that the wearer's skin is damaged by the waist-side edge of the absorbent body.

Therefore, an object of the present invention is to provide an absorbent article in which the waist side edge of the absorbent body is less likely to damage the wearer's skin.

solution to the problem

The main aspect of the present invention for solving the first problem is an absorbent article having longitudinal and transverse directions, the absorbent article comprising: an absorbent body including an absorbent core; and a pair of waist portions each Each waist part includes a skin side panel part arranged at a position closest to the skin side and a plurality of elastic threads capable of expanding and contracting in the lateral direction, and a plurality of elastic threads in the pair of waist In at least one waist part among the parts, the flexural rigidity of the skin side panel part based on the KES method is 0.0096 N·m ² /m×10 ^-4 or less, the waist part has an inner layer part, and the inner layer part is The layer sheet part is located on the waist side in the longitudinal direction with respect to the absorptive main body, and the inner layer sheet part is located between the skin side sheet part and the elastic thread in the thickness direction of the waist part. The flexural rigidity of the inner-layer sheet portion by the KES method is higher than the flexural rigidity of the skin-side sheet portion.

The main aspect of the present invention for solving the second problem is an absorbent article having longitudinal and transverse directions, the absorbent article comprising: an absorbent body including an absorbent core; and a pair of waist portions each Each of the waist portions includes a skin side panel portion disposed at the most skin-side position, and in at least one of the pair of waist portions, the flexural rigidity of the skin side panel portion based on the KES method is 0.0096 N·m ² /m×10 ⁻⁴ or less, an inner layer sheet portion is arranged on the non-skin side with respect to the skin side sheet portion, and the flexural rigidity of the inner layer sheet portion by KES method is higher than that of the skin The side sheet part has high flexural rigidity, and the inner layer sheet part is arranged on the skin side of the absorptive main body so as to span the waist side edge of the absorptive main body in the longitudinal direction.

Other features of the present invention will become apparent by reading the description of this specification with reference to the accompanying drawings.

effect of invention

Regarding the first problem, the effect of the present invention is to provide an absorbent article that is less likely to cause line marks on the waist of the wearer.

Regarding the second problem, the effect of the present invention is to provide an absorbent article in which the waist side edge of the absorbent body is less likely to damage the wearer's skin.

Description of drawings

FIG. 1 is a perspective view of the underpants-type disposable diaper 1 .

Fig. 2 is a plan view of the diaper 1 in an expanded state and an extended state.

FIG. 3 is a cross-sectional view taken along line I-I in FIG. 2 .

FIG. 4A is a schematic cross-sectional view of the waist portion 40 according to the comparative example taken in the thickness direction, and FIG. 4B is a schematic cross-sectional view of the waist portion 20 taken in the thickness direction according to the embodiment.

FIG. 5 is an enlarged cross-sectional view of the abdominal waist portion 20 shown in FIG. 3 .

FIG. 6 is a cross-sectional view of a modification of the waist portion 20 .

FIG. 7 is a cross-sectional view of a modification of the waist portion 20 .

FIG. 8 is a cross-sectional view of a modification of the waist portion 20 .

FIG. 9 is a cross-sectional view of a modification of the waist portion 20 .

Fig. 10 is a perspective view of the underpants-type disposable diaper 1 according to the second embodiment.

Fig. 11 is a plan view of the diaper 1 in a developed and extended state.

FIG. 12 is a cross-sectional view taken along line I-I in FIG. 11 .

13A is a schematic cross-sectional view showing a contracted state of the skin side sheet portion 40 according to the comparative example, and FIG. 13B is a schematic cross-sectional view showing a contracted state of the skin side sheet portion 221 according to the embodiment.

FIG. 14 is an enlarged view of a cross-sectional view of the abdominal waist portion 20 shown in FIG. 12 .

FIG. 15 is a cross-sectional view of a modification of the waist portion 20 .

FIG. 16 is a cross-sectional view of a modification of the waist portion 20 .

FIG. 17 is a cross-sectional view of a modification of the waist portion 20 .

Detailed ways

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

An absorbent article having longitudinal and transverse directions, the absorbent article comprising: an absorbent body including an absorbent core; and a pair of waist portions each including a skin side panel portion and a plurality of elastic threads, The skin side panel portion is arranged at a position closest to the skin side, the plurality of elastic threads can be stretched and contracted in the lateral direction, and in at least one waist portion of the pair of waist portions, the skin side panel The flexural rigidity by KES method of the waist part is 0.0096 N·m ² /m×10 ^-4 or less, and the waist part has an inner layer sheet part in the longitudinal direction with respect to the absorptive main body. on the waist side, the inner layer sheet portion is located between the skin side sheet portion and the elastic thread in the thickness direction of the waist portion, and the flexural stiffness ratio of the inner layer sheet portion based on the KES method The flexural rigidity of the skin side panel portion is high.

According to such an absorbent article, the flexural rigidity of the skin side panel portion is low. Therefore, the concavities and convexities formed on the waist portion due to the contraction of the elastic thread are easily crushed, so that wrinkles are hardly generated on the waist portion of the wearer. In addition, since the linear load of the elastic thread is absorbed and relieved by the inner layer sheet portion, thread marks are less likely to be caused on the waist of the wearer.

In such an absorbent article, the waist portion includes a non-skin side sheet portion arranged at a position closest to the non-skin side, and the elastic thread is arranged on the inner layer sheet portion and all the inner layer sheet portions in the thickness direction. between the non-skin side sheet portions, and the skin side sheet portion is a portion formed by folding the waist side end portion in the longitudinal direction of the non-skin side sheet portion toward the skin side.

According to such an absorbent article, similar to the flexural rigidity of the skin-side sheet portion, the flexural rigidity of the non-skin side sheet portion is low, so that the feel of the waist portion from the non-skin side can be improved.

In such an absorbent article, the waist side edge part in the said longitudinal direction of the said inner layer sheet part is folded toward the skin side.

According to such an absorbent article, since the inner layer sheet part arranged on the skin side with respect to the elastic thread forms two layers, it is less likely that a thread mark will be generated on the waist of the wearer.

In such an absorbent article, the waist portion includes a second inner layer sheet portion and a non-skin side sheet portion, the second inner layer sheet portion is disposed on the non-skin side with respect to the inner layer sheet portion, and the The non-skin side sheet portion is arranged at the position closest to the non-skin side, the flexural rigidity of the second inner layer sheet portion based on the KES method is 0.0096 N·m ² /m×10 ⁻⁴ or less, and the elastic thread is arranged between the second inner layer sheet portion and the non-skin side sheet portion in the thickness direction, and the skin side sheet portion is formed by placing the non-skin side sheet portion in the longitudinal direction The part of the waist side end folded toward the skin side.

According to such an absorbent article, even when the flexural rigidity of the second inner layer sheet portion is low, since the linear load of the elastic thread is absorbed and relieved by the inner layer sheet portion, line marks are less likely to be generated on the waist of the wearer.

In such an absorbent article, the waist portion includes a third inner layer sheet portion and a non-skin side sheet portion, the third inner layer sheet portion is arranged on the non-skin side with respect to the inner layer sheet portion, and the The non-skin side panel part is arranged at the position most on the non-skin side, the waist part has a waist side part and a core side part, and the waist part is located on the waist side in the longitudinal direction with respect to the absorbent main body part, the core side part is a part overlapping the absorptive core in the thickness direction, the plurality of elastic threads includes a waist side elastic thread arranged on the waist side part and a waist side elastic thread arranged on the core A core-side elastic thread of a side portion, the waist-side elastic thread is arranged between the inner layer sheet portion and the third inner layer sheet portion in the thickness direction, and the core-side elastic thread is arranged in the thickness direction between the inner layer sheet portion and the third inner layer sheet portion The thickness direction is disposed between the third inner layer sheet portion and the non-skin side sheet portion.

According to such an absorbent article, the waist-side elastic thread is less likely to be visually recognized from the non-skin side, so that the user can be given an impression that the waist-side portion has a soft fit. On the other hand, the core-side elastic strands are easily visually recognized from the non-skin side, so that the user can be impressed that the absorbent core has high fit and less leakage.

In such an absorbent article, the waist portion has an intermediate portion between the waist side portion and the core side portion in the longitudinal direction, and the plurality of elastic threads includes a intermediate elastic threads, and some of the intermediate elastic threads are arranged at positions between the inner layer sheet portion and the third inner layer sheet portion in the thickness direction, and some of the intermediate elastic threads are arranged in the thickness direction The thickness direction is arranged at a position between the third inner layer sheet portion and the non-skin side sheet portion.

According to such an absorbent article, the stretching force of the intermediate portion can be increased, so that the sagging of the absorbent main body can be suppressed.

In such an absorbent article, the waist part has a waist side part, which is a part located on the waist side in the longitudinal direction with respect to the absorptive main body, and an absorbent main body side part, and the absorbent main body is located on the waist side in the longitudinal direction. The side portion of the absorbent body is a portion overlapping with the absorbent body in the thickness direction, and the magnitude of the force for extending the side portion of the waist portion per unit length in the lateral direction is divided by the amount of the side portion of the waist portion. The value obtained by the length in the longitudinal direction is less than the magnitude of the force for extending the side part of the absorbent main body per unit length in the transverse direction divided by the length of the side part of the absorbent main body in the longitudinal direction. obtained value.

According to such an absorbent article, since the stretchable force of the side portion of the waist is smaller than that of the side portion of the absorbent main body, it is less likely that wrinkles or line marks will be formed on the waist of the wearer.

In such an absorbent article, the waist-side end of the inner layer sheet portion is located at the waist in the longitudinal direction with respect to the elastic thread arranged at the most waist-side position among the plurality of elastic threads side.

According to such an absorbent article, with respect to more elastic threads, the inner layer sheet portion can be arranged on the skin side, so that thread marks are less likely to be generated on the waist of the wearer.

In such an absorbent article, the crotch side end of the inner layer sheet portion is located on the crotch side in the longitudinal direction with respect to the waist side end of the absorbent main body.

According to such an absorbent article, with respect to more elastic threads, the inner layer sheet portion can be arranged on the skin side, so that thread marks are less likely to be generated on the waist of the wearer.

In such an absorbent article, the flexural rigidity by the KES method of the skin side sheet portion is 0.0035 N·m ² /m×10 ^-4 or more.

According to such an absorbent article, the appropriate tensile strength of the skin side panel portion can be obtained, so that breakage of the waist portion during use can be suppressed.

In such an absorbent article, the compression recovery rate RC by the KES method of the said skin side panel part is 15% or more and 50% or less.

According to such an absorbent article, the unevenness|corrugation formed in the waist part by the shrinkage of an elastic thread is easily crushed, and a wrinkle|wrinkle|wrinkle does not generate|occur|produce in the waist part of a wearer almost.

In such an absorbent article, the basis weight of the skin side sheet portion is 10 g/m ² or more and 30 g/m ² or less, and the skin side sheet portion has 0.12 g/cm ³ or more under a load of 49.03 hPa And the apparent density of 0.2g/ ^cm3 or less.

According to such an absorbent article, the flexural rigidity of the skin side panel portion can be reduced, and the flexibility thereof can be improved.

In such an absorbent article, the skin side sheet portion contains fibers having a fiber diameter of 14 μm or more and 22 μm or less, and the coefficient of variation MMD/MIU×100 of the coefficient of friction of the skin side sheet portion by the KES method is 2 % or more and 6% or less.

According to such an absorbent article, the skin side panel portion has relatively many fibers, which have little variation in the coefficient of friction and are in contact with the user's fingertips in such a manner as to adhere to the user's fingertips. Provides a smooth, pliable and soft feel.

In such an absorbent article, the friction coefficient MIU of the skin side panel portion is at least 0.25.

According to such an absorbent article, the skin side panel portion has relatively many fibers, and these fibers are in contact with the user's fingertips so as to adhere to the user's fingertips. Provides a smooth, pliable and soft feel.

In such an absorbent article, the said skin side sheet part contains polyethylene fiber.

According to such an absorbent article, polyethylene fibers are more flexible than other thermoplastic resin fibers such as polypropylene fibers and PET (polyethylene terephthalate) fibers and the like. Therefore, the flexural rigidity of the skin side panel portion can be reduced, and the flexibility thereof can be improved.

An absorbent article having a longitudinal direction and a transverse direction, the absorbent article comprising: an absorbent body including an absorbent core; and a pair of waist portions each including a position disposed at the skin-most side The skin side panel portion, in at least one of the pair of waist portions, the flexural rigidity of the skin side panel portion based on the KES method is 0.0096 N·m ² /m×10 ⁻⁴ or less, relative to An inner layer sheet portion is arranged on the non-skin side of the skin side sheet portion, the flexural rigidity of the inner layer sheet portion by the KES method is higher than the flexural rigidity of the skin side sheet portion, and the inner layer sheet portion is The part is arranged on the skin side of the absorbent body and spans the waist side end edge of the absorbent body in the longitudinal direction.

According to such an absorbent article, the flexural rigidity of the skin side panel portion is low. Therefore, the tactile feeling of the wearer can be improved. In addition, the unevenness formed by the shrinkage of the waist portion is easily crushed, so that wrinkles are hardly formed on the waist of the wearer. Moreover, since the hardness and the step of the edge of the absorptive main body are absorbed and relieved by the inner layer sheet part, it is possible to prevent the wearer's skin from being damaged by the edge of the absorptive main body.

In such an absorbent article, the waist portion includes a non-skin side sheet portion arranged at a position closest to the non-skin side, the skin side sheet portion being obtained by placing the non-skin side sheet portion on the A portion in which a longitudinal waist end portion is folded toward the skin side, and the inner layer sheet portion has a skin side portion and a non-skin side portion, and the skin side portion is formed by orienting the longitudinal waist end portion toward the skin side. A portion in which the skin side is folded, the non-skin side portion is a portion disposed on the non-skin side with respect to the skin side portion, and in the thickness direction of the waist portion, the non-skin side portion of the inner layer sheet portion is A stretchable member is arranged between the side portion and the non-skin side sheet portion, the stretchable member is capable of expanding and contracting in the lateral direction, and the skin side portion of the inner layer sheet portion is arranged on the side of the absorptive body. The skin side spans the waist side edge in the longitudinal direction of the absorptive main body.

According to such an absorbent article, the inner layer sheet portion absorbs and relieves the hardness and step of the edge of the absorptive main body, so that the edge of the absorptive main body can be prevented from damaging the wearer's skin. In addition, similar to the skin side panel portion, the non-skin side panel portion has a low flexural rigidity, so that the feel of the waist portion from the non-skin side can be improved.

In such an absorbent article, the crotch-side edge of the skin-side portion of the inner layer sheet portion is located on the crotch side in the longitudinal direction with respect to the waist-side edge of the absorbent core.

According to such an absorbent article, the inner layer sheet part absorbs and relieves the hardness and the step of the edge of the absorptive core, so that the edge of the absorptive core can be suppressed from damaging the wearer's skin.

In such an absorbent article, in the thickness direction of the waist portion, a stretchable sheet portion is disposed between the skin side portion and the non-skin side portion of the inner layer sheet portion, and the stretchable sheet portion is capable of Expanding and contracting in the lateral direction, the elastic sheet portion has a higher flexural rigidity based on the KES method than the skin side sheet portion, and the elastic sheet portion is disposed on the skin of the absorbent body side, spanning the waist side edge of the absorbent body in the longitudinal direction.

According to such an absorbent article, the inner layer sheet portion and the stretchable sheet portion absorb and reduce the hardness and step of the edge of the absorbent main body, so that the edge of the absorbent main body can be further suppressed from damaging the wearer's skin.

In such an absorbent article, the crotch side edge of the skin side portion of the inner layer sheet portion, the crotch side edge edge of the skin side sheet portion, and the crotch side edge of the elastic sheet portion are in the longitudinally offset from each other.

According to such an absorbent article, the steps at the end edges of the respective sheet portions are reduced, so that it is possible to suppress the wearer's skin from being damaged by the end edges of the respective sheet portions.

In such an absorbent article, the crotch-side edge of the skin-side portion of the inner-layer sheet portion is located at the most crotch-side position in the longitudinal direction.

According to such an absorbent article, it is possible to suppress the phenomenon that the skin side sheet portion with low rigidity is positioned closest to the crotch side, causing it to be twisted, and the stretchable sheet portion is positioned closest to the crotch side, causing it to curl.

In such an absorbent article, the said inner-layer sheet part is a stretchable sheet part which can expand and contract in the said lateral direction.

According to such an absorbent article, the hardness and step of the edge of the absorbent body are absorbed and relieved by the stretchable sheet portion, and local constriction can be suppressed by bringing the waist portion into close contact with the wearer on the ground. Therefore, damage to the waist of the wearer can be further prevented.

In such an absorbent article, the crotch side edge of the elastic sheet portion is located on the waist side in the longitudinal direction with respect to the waist side edge of the absorptive core.

According to such an absorbent article, excessive shrinkage of the absorptive core by the stretchable sheet portion can be suppressed. The flatness of the absorbent core can be maintained.

In such an absorbent article, the skin side sheet portion is arranged on the skin side of the absorptive main body and spans the waist side edge of the absorptive main body in the longitudinal direction.

According to such an absorbent article, since the hardness and step of the edge of the absorbent body are absorbed and relaxed by the inner layer sheet and the skin side sheet, the wearer's skin can be further suppressed from being damaged by the edge of the absorptive body.

In such an absorbent article, the flexural rigidity by the KES method of the skin side sheet portion is 0.0035 N·m ² /m×10 ^-4 or more.

According to such an absorbent article, appropriate tensile strength of the skin side panel portion can be obtained, so that breakage of the waist portion during use can be suppressed.

In such an absorbent article, the compression recovery rate RC by the KES method of the said skin side panel part is 15% or more and 50% or less.

According to such an absorbent article, the unevenness|corrugation formed in the waist part by the contraction|shrinkage of an elastic thread is easy to be crushed, and a wrinkle mark hardly arises in a wearer's waist part.

In such an absorbent article, the basis weight of the skin side sheet portion is 10 g/m ² or more and 30 g/m ² or less, and the skin side sheet portion has 0.12 g/cm ³ or more under a load of 49.03 hPa And the apparent density of 0.2g/ ^cm3 or less.

According to such an absorbent article, the flexural rigidity of the skin side panel portion can be reduced, and the flexibility thereof can be improved.

In such an absorbent article, the skin side sheet portion contains fibers having a fiber diameter of 14 μm or more and 22 μm or less, and the coefficient of variation MMD/MIU×100 of the coefficient of friction of the skin side sheet portion by the KES method is 2 % or more and 6% or less.

According to such an absorbent article, the skin side sheet portion has many fibers, and these fibers have less variation in the coefficient of friction and are in contact with the user's fingertips so as to adhere to the user's fingertips. Provides a smooth, pliable and soft feel.

In such an absorbent article, the friction coefficient MIU of the skin side panel portion is at least 0.25.

According to such an absorbent article, the skin side sheet portion has many fibers, and these fibers are in contact with the user's fingertips so as to adhere to the user's fingertips. Provides a smooth, pliable and soft feel.

In such an absorbent article, the said skin side sheet part contains polyethylene fiber.

According to such an absorbent article, polyethylene fibers are more flexible than other thermoplastic resin fibers such as polypropylene fibers and PET (polyethylene terephthalate) fibers and the like. Therefore, the flexural rigidity of the skin side panel portion can be reduced, and the flexibility thereof can be improved.

=== Implementation ===

Hereinafter, an embodiment of the absorbent article according to the present invention will be described using an underpants-type disposable diaper for infants as an example. However, the absorbent article according to the present invention is not limited to the underpants-type disposable diaper for infants, and can be applied to underpants-type disposable diapers for adults, belt-type disposable diapers, sanitary panties, and the like.

<First Embodiment>

===Structure of the underpants-type disposable diaper 1 ===

Fig. 1 is a perspective view of a pants-type disposable diaper 1 (hereinafter, referred to as "diaper"). Fig. 2 is a plan view of the diaper 1 in an unfolded and extended state. FIG. 3 is a cross-sectional view taken along line I-I in FIG. 2 .

In the shorts type state shown in FIG. 1, the diaper 1 has a longitudinal direction, a lateral direction, and a front-rear direction, and has a waist opening BH and a pair of leg openings LH. In the longitudinal direction, the waist side is defined as the upper side, and the crotch side is defined as the lower side. In the front-rear direction, the front side of the wearer is defined as the front side, and the back side of the wearer is defined as the rear side. As shown in FIG. 3, the direction in which the materials which comprise the diaper 1 are laminated|stacked is a thickness direction. In the thickness direction, the side of the diaper 1 in contact with the wearer is defined as the skin side, and the side of the diaper 1 not in contact with the wearer is defined as the non-skin side.

The diaper 1 includes an absorbent main body 10 and a pair of waist portions 20 and 30, which are three members that are rectangular in plan view. Of the pair of waist portions 20 and 30 , one attached to the wearer's ventral portion is the ventral waist portion 20 , and the other attached to the wearer's back portion is the dorsal waist portion 30 .

In the diaper 1 in the unfolded state shown in FIG. 2 , the abdominal waist portion 20 and the back waist portion 30 are arranged such that the lengthwise directions of these portions extend in the lateral direction of the diaper 1 . One end in the longitudinal direction of the absorptive main body 10 is arranged in the lateral center portion of the abdominal waist portion 20 . The end on the other side in the longitudinal direction of the absorptive main body 10 is arranged in the lateral center portion of the back waistline portion 30 .

In the diaper 1 in the unfolded state shown in FIG. 2 , the absorptive main body 10 is substantially folded in half at the center in the longitudinal direction so that the longitudinal direction extends along the longitudinal direction of the diaper 1 . Then, in the lateral direction of the diaper 1, both side end portions of the abdominal waist portion 20 and both side end portions of the back side waist portion 30 are joined together by welding or by using an adhesive to form the pants type shown in FIG. 1 . Diapers 1.

As shown in FIG. 3 , the absorptive main body 10 includes an absorber 11 , a liquid-permeable topsheet 12 disposed on the skin side with respect to the absorber 11 , and a liquid-impermeable topsheet 12 disposed on the non-skin side with respect to the absorber 11 The back sheet 13 and the exterior sheet 14 arranged on the non-skin side with respect to the back sheet 13 . The exterior sheet 14 is preferably a flexible sheet.

As shown in FIG. 2 , the absorber 11 includes an absorptive core 11A that absorbs and retains excretion fluid such as urine, and a liquid-permeable core wrap sheet 11B that covers the absorptive core 11A. An example of the absorbent core 111A may be obtained by forming liquid-absorbent fibers such as pulp containing a superabsorbent polymer (so-called SAP) into a predetermined shape. Note that the absorbent core 11A is not limited to being covered with the core wrap sheet 11B.

As shown in FIG. 2 , leg elastic members 15 are provided on both lateral sides of the absorptive main body 10 . Therefore, the diaper 1 is fitted to the leg of the wearer. The leg elastic members 15 are fixed between two outer sheets 14 folded inward in the lateral direction in a state of being elongated in the longitudinal direction of the absorptive main body 10 . Examples of the leg elastic members 15 may be elastic threads and elastic nonwoven fabrics.

As shown in FIG. 3 , the abdominal waist portion 20 (the back waist portion 30 ) includes a first sheet 21 ( 31 ), a second sheet 22 ( 32 ), and a plurality of elastic threads 23 ( 33 ) that can expand and contract in the lateral direction. A plurality of elastic threads 23 ( 33 ) are arranged side by side in the longitudinal direction between the first sheet 21 ( 31 ) and the second sheet 22 ( 32 ), and are fixed in a state of being elongated in the lateral direction. Therefore, the abdominal waist part 20 and the back waist part 30 expand and contract in the lateral direction and fit to the waist of the wearer. Suitable examples of the elastic threads 23 and 33 are styrene-based rubber, urethane-based rubber, ester-based rubber, and other known synthetic rubbers made of polyurethane or polyethylene, in addition to the natural rubber in the form of threads.

In the present embodiment, as an example of a pant-type disposable diaper, a so-called three-piece type in which the abdominal waist portion 20 and the back waist portion 30 are separated and includes the abdominal waist portion 20, the back waist portion 30 and the Absorbent body 10 . However, it is not limited to this. For example, a so-called two-piece pant-type disposable diaper including two members, that is, an absorbent main body and an outer member, in which the abdominal waist part 20 and the back waist part 30 are integrated, and the abdominal waist part can be integrated, can be used. The part 20 and the back waist part 30 are continuous in the crotch part, and form a unit.

===Characteristic part of waist part 20 and 30 ===

4A is a schematic cross-sectional view of the waist portion 40 taken in the thickness direction according to the comparative example, and FIG. 4B is a schematic cross-sectional view of the waist portion 20 taken in the thickness direction according to the present embodiment. FIG. 5 is an enlarged view of a cross-sectional view of the abdominal waist portion 20 shown in FIG. 3 .

At least one of the pair of waist portions 20 and 30 included in the diaper 1 according to the present embodiment has the following characteristic parts. Hereinafter, the ventral waist portion 20 will be described as an example; however, the dorsal waist portion 30 does not necessarily have the following characteristic parts. Alternatively, both the ventral waist portion 20 and the dorsal waist portion 30 may have the following features; or the dorsal waist portion 30 alone may have the following features while the ventral waist portion 20 does not have the following features part.

As described above, the abdominal waist portion 20 (hereinafter, also simply referred to as “waist portion 20 ”) includes the first sheet 21 , the second sheet 22 , and the plurality of elastic threads 23 . A part of the second sheet 22 serves as the non-skin side sheet portion 222 , and the non-skin side sheet portion 222 is a portion arranged on the most non-skin side of the waist portion 20 . The other part of the second sheet 22 serves as the skin-side sheet portion 221, and the other portion is opposed to the absorbent main body by folding the longitudinal waist-side end portion of the second sheet 22 (of the non-skin-side sheet portion 222) toward the skin side 10 The part on the skin side. The plurality of elastic threads 23 are arranged between the first sheet 21 and the non-skin side sheet portion 222 in the thickness direction.

The skin-side sheet portion 221 is fixed to the first sheet 21 and the absorptive main body 10 with the adhesive 50 . The longitudinal length of the skin-side sheet portion 221 is smaller than the longitudinal length of the non-skin-side sheet portion 222 , and is a length that allows the crotch-side end portion of the skin-side sheet portion 221 to cover the waist-side end portion of the absorptive main body 10 . Therefore, the skin side sheet part 221 does not cover the absorptive main body 10 excessively, which suppresses the reduction of the area in which the absorptive main body 10 can absorb. Moreover, the waist side edge part of the absorptive main body 10 can be covered with the skin side sheet part 221, so that the end part of the absorptive main body 10 can be suppressed from being opened.

The first sheet 21 is arranged between the skin-side sheet portion 221 and the elastic thread 23 in the thickness direction. A part of the 1st sheet|seat 21 is arrange|positioned at the waist side with respect to the absorptive main body 10 in the longitudinal direction. The first sheet 21 corresponds to the inner layer sheet portion. The first sheet 21 is fixed to the skin side sheet portion 221 and the absorptive main body 10 with the adhesive 50 .

Since the skin side sheet portion 221 is in direct contact with the wearer's skin, a soft sheet with low flexural rigidity is used. Therefore, the skin side panel portion 221 has a smooth, flexible and soft feel, thereby improving the feel on the wearer's skin.

As a result of the test conducted by the inventors, it was found that the flexural rigidity by the KES method of the skin side panel portion 221 is preferably 0.0096 N·m ² /m×10 ⁻⁴ or less. Generally, the waist portion 20 of the diaper 1 is provided with elastic threads 23 that can expand and contract in the lateral direction so as to fit the waist of the wearer. The waist portion 20 is contracted in the lateral direction by the elastic thread 23 , and irregularities are formed in the thickness direction, and the irregularities are located in the waist portion 20 side by side in the lateral direction. The unevenness is long in the longitudinal direction; in other words, longitudinal pleats are formed in the waist portion 20 .

Therefore, in the case where the flexural rigidity of the skin-side sheet portion 221 is greater than 0.0096 N·m ² /m×10 ⁻⁴ and the skin-side sheet portion 221 has high Large and uniform unevenness was formed, as in the comparative example shown in FIG. 4A . Furthermore, the shape retention (resilience) of the protruding portion 42 protruding toward the skin side is improved. When the waist portion 40 is in contact with the wearer, the protrusions 42 are hardly crushed, and the protrusions 42 may bite deeply into the wearer's skin. Accordingly, longitudinal folds (indentations formed by the protrusions 42 ) may be produced on the wearer's skin.

In contrast, according to the present embodiment, the flexural rigidity of the skin side panel portion 221 is set to be 0.0096 N·m ² /m×10 ⁻⁴ or less. As the skin-side sheet portion 221, a sheet having high drapeability and hanging down loosely is used. Therefore, as shown in FIG. 4B , in the waist portion 20 according to the present embodiment, uneven unevenness having repeated fine undulations is formed due to the contraction of the elastic thread 23 . That is, the waist portion 20 is smooth, and the contact area between the waist portion 20 and the wearer's skin can be increased. Therefore, the contact pressure of the waist portion 20 due to the elastic thread 23 can be dispersed, and thus the large protrusions 42 such as shown in FIG. 4A according to the comparative example do not locally contact the wearer's skin. Furthermore, the shape retention (resilience) of the protruding portion 26 decreases. Therefore, when the waist portion 20 is in contact with the wearer, the protrusions 26 may be crushed, and the protrusions 26 are less likely to bite into the wearer's skin. This results in virtually no vertical creases on the wearer's skin. Therefore, at least one of the lateral flexural rigidity and the longitudinal flexural rigidity of the skin side panel portion 221 needs to be 0.0096 N·m ² /m×10 ⁻⁴ or less. Preferably, the transverse flexural stiffness, which largely affects the formation of wrinkles, is 0.0096 N·m ² /m×10 ⁻⁴ or less. More preferably, the flexural stiffness in both directions is 0.0096 N·m ² /m×10 ⁻⁴ or less.

However, when the flexural rigidity of the skin-side sheet portion 221 is 0.0096 N·m ² /m×10 ⁻⁴ or less, the cushioning properties of the skin-side sheet portion 221 become weak. Therefore, for example, when only the skin side sheet portion 221 is arranged on the skin side of the elastic thread 23, the linear load of the elastic thread 23 is less likely to be absorbed and relieved by the skin side sheet portion 221. When the skin-side sheet portion 221 has high drapeability, in a state in which the skin-side sheet portion 221 is adhered to the periphery of the elastic thread 23 , that is, in a state in which the outline of the elastic thread 23 emerges from the skin-side surface of the waist portion 20 , the waist portion 20 is in contact with the wearer's skin. In this case, the linear load of the elastic threads 23 may be exerted on the wearer's skin, making it more likely that line marks (indentations of the elastic threads 23 ) are produced on the wearer's skin.

In particular, regarding the elastic threads 23a to 23e (hereinafter, also referred to as "waist side elastic threads") arranged on the waist side with respect to the absorptive main body 10, the absorptive main body 10 is not located on the skin side of these waist side elastic threads. Therefore, traces of the waist elastic threads 23a to 23e may be produced on the wearer's skin. The waist of an infant who is a target wearer of the diaper 1 according to the present embodiment protrudes in many cases. Therefore, the waist-side elastic threads 23a to 23e may bite into the protruding waist of the infant, and line marks may be generated on the waist of the infant.

Therefore, in the present embodiment, the inner layer sheet portion 21 is arranged between the skin side sheet portion 221 and the elastic thread 23 in the thickness direction of the waist portion 20 , and at least a part of the inner layer sheet portion 21 is arranged with respect to the absorptive main body 10 On the waist side. The flexural rigidity of the inner layer sheet portion 21 by the KES method is set to a higher (larger) value than the flexural rigidity of the skin-side sheet portion 221 .

Therefore, the inner layer sheet portion 21 having a higher cushioning property than the skin side sheet portion 221 is arranged on the skin side with respect to the waist elastic threads 23a to 23e, and the linear load of the waist elastic threads 23a to 23e is affected by the inner layer sheet Part 21 absorbs ease. Since the inner layer sheet portion 21 is less likely to adhere to the waistline-side elastic threads 23a to 23e, the contours of the waistline-side elastic threads 23a to 23e are less likely to emerge from the skin-side surface of the waistline portion 20. Therefore, the waist-side elastic threads 23a to 23e are less likely to bite into the waist of the wearer, and are less likely to produce thread marks on the waist of the wearer. Note that the flexural rigidity of at least one of the lateral direction and the longitudinal direction of the inner layer sheet portion 21 may be higher than the flexural rigidity of at least one of the lateral direction and the longitudinal direction of the skin side sheet portion 221 .

That is, in the case of the diaper 1 according to the present embodiment, wrinkles and line marks of vertical pleats are less likely to be formed on the waist of the wearer, so that it is possible to prevent the sensitive skin of the infant from being damaged. In addition, the inner layer sheet part 21 is not located at the most skin side, and the skin side sheet part 221 which is softer than the inner layer sheet part 21 is located at the most skin side. A good feel on the wearer's skin can be maintained.

The flexural rigidity of the skin-side sheet portion 221 is more preferably 0.007 N·m ² /m×10 ⁻⁴ or less. Therefore, it is less likely that longitudinal fold marks will be created on the waist of the wearer. The flexural rigidity of the inner layer sheet portion 21 is preferably 0.0096 N·m ² /m×10 ⁻⁴ or more, or more preferably 0.015 N·m ² /m×10 ⁻⁴ or more. Alternatively, the flexural stiffness of the inner-layer sheet portion 21 may be more than twice that of the skin-side sheet portion 221, or the difference between the two flexural stiffnesses may be 0.005 N·m ² /m×10 ⁻⁴ above. This makes it less likely that line marks will be created on the waist of the wearer.

In the waist portion 20 shown in FIG. 5, the elastic thread 23 elongated in the lateral direction is sandwiched and fixed between a part of the first sheet 21 and the second sheet 22 (non-skin side sheet portion 222), and the first sheet This portion of the sheet 21 serves as the inner-layer sheet portion 21 . Therefore, as in the waist portion 20 of FIG. 7 to be described later, compared with the case where the inner sheet portion 24 with high rigidity is provided in addition to the first sheet 21 and the second sheet 22 with the elastic thread 23 sandwiched therebetween , the construction can be simplified.

In addition, in the waist portion 20 shown in FIG. 5 , a portion formed by folding the longitudinal waist side end of the second sheet 22 (of the non-skin side sheet portion 222 ) toward the skin side is used as the skin side sheet portion 221 . Therefore, like the skin-side sheet portion 221, the non-skin-side sheet portion 222 has a flexural rigidity by the KES method of 0.0096 N·m ² /m×10 ^-4 or less, and thus is a soft sheet. This makes it possible to improve the feel of the waist portion 20 on the non-skin side. In particular, in the case of the diaper 1 for infants, since the infant caregiver or the like does not wear the diaper 1, the infant caregiver or the like can hardly feel the good touch of the waist portion 20 on the skin side. The improvement of the feel of the waist portion 20 on the non-skin side can give an impression to the caregivers of infants and the like that the diaper 1 is a product with a good feel.

However, the present invention is not limited to the configuration of the waist portion 20 shown in FIG. 5 . For example, the skin side panel portion 221 and the non-skin side panel portion 222 may be formed from separate sheets. The flexural rigidity of the non-skin side panel portion 222 is not limited to 0.0096 N·m ² /m×10 ⁻⁴ or less.

Note that the flexural rigidity of the skin side sheet portion 221 based on the KES method and the flexural rigidity of the inner layer sheet portion 21 based on Flexural stiffness by KES method. Specifically, both the skin side sheet portion 221 and the inner layer sheet portion 21 were cut into pieces of 10 cm×10 cm used as samples. Then, each sample was fixed between the chucks of the measuring testing machine so that the flexural stiffness of the sample in the transverse direction could be measured. Each sample was bent anteriorly to a maximum curvature of +2.5cm" ¹ , and inwardly to a maximum curvature of -2.5cm" ¹ , and then returned to its original position. The flexural stiffness value was calculated from the average value of the inclination when the inclination of the bending moment with respect to the curvature was substantially constant after starting the forward bending and the inclination when the inclination of the bending moment with respect to the curvature was substantially constant after starting the inward bending . The measurement was repeated five times for each sample, and the average of the obtained values was used as the flexural stiffness. The flexural rigidity (described later) of other sheet portions can also be measured in the same manner.

In this case, in the waist part 20, the part located on the waist side with respect to the absorptive main body 10 in the longitudinal direction is called waist side part 20A, and the part overlapping the absorptive main body 10 in the thickness direction is called as the waist part 20A. Absorbent body side 20B. In the absorptive main body side part 20B, the part overlapping with the absorptive core 11A in the thickness direction is called core side part 20D, and the part between the waistline side part 20A and the core side part 20D in the longitudinal direction is called an intermediate part Section 20C.

It is preferable that the value (F1/L1) obtained by dividing the magnitude of the force F1 for extending the waistline side portion 20A unit length in the lateral direction by the longitudinal length L1 of the waistline side portion 20A is smaller than the unit length extending the absorptive main body side portion 20B in the lateral direction. A value obtained by dividing the magnitude of the force F2 by the longitudinal length L2 of the absorbent body side portion 20B (F2/L2).

That is, it is preferable that the lateral expansion-contraction force per unit width in the longitudinal direction of the waistline side part 20A is smaller than the lateral expansion-contraction force per unit width in the longitudinal direction of the absorptive main body side part 20B. This can reduce the pinching of the wearer's waist caused by the waist-side elastic threads 23a to 23e. Therefore, it is less likely that line marks will be created on the waist of the wearer. On the other hand, increasing the stretching force of the absorbent body side portion 20B allows the absorbent body 10 to come into close contact with the wearer. This makes it possible to hardly create a gap between the absorbent main body 10 and the wearer, so that leakage of excrement can be suppressed. In addition, in the case where the absorptive main body 10 absorbs excrement and increases in weight, the sagging of the absorptive main body 10 can be suppressed, so that the fit of the absorptive main body 10 can be maintained.

For example, in the case where the lateral stretching force is reduced, at least one of the following adjustments can be made: reduce the fineness of the elastic thread 23 (reduce the diameter); reduce the elongation ratio of the elastic thread 23; reduce the elastic thread 23 effective length; reduce the number of elastic threads 23 per unit width in the longitudinal direction. The elongation ratio of the elastic thread 23 is the elongation length when the natural length of the elastic thread 23 is defined as 1. The effective length of the elastic thread 23 is the length of the portion where the elastic thread 23 exhibits stretchability, and is the length of the portion where the elastic thread 23 in the stretched state is fixed to the sheet. In the case of increased lateral telescoping forces, the adjustment can be made in the opposite way.

Specifically, the fineness of the waist elastic threads 23a to 23e may be about 200 to 1100 dtex, or preferably about 300 to 1000 dtex. If the fineness is less than 200 dtex, there is a risk that the elastic threads 23a to 23e cannot exhibit the required stretchability. If the fineness is larger than 1100 dtex, there is a risk that the elastic threads 23 are more likely to be visually recognized from the outside of the diaper 1, giving the user the impression that the diaper 1 is constricting the waist. Specifically, the pitch of the waist-side elastic threads 23a to 23e (the distance between the centers of the elastic threads 23 adjacent to each other in the longitudinal direction) may be in the range of about 2.0 mm to 12.0 mm, or preferably about 4.0 mm to 4.0 mm. within the range of 10.0mm. Therefore, when the waist portion 20 is fitted to the wearer, it is less likely that wrinkles or lines will be created on the wearer's waist.

Further, it is preferable to make the core side portion 20D elongate in the lateral direction by maximizing the value (F3/L3) obtained by dividing the magnitude of the force F3 for extending the intermediate portion 20C per unit length in the lateral direction by the longitudinal length L3 of the intermediate portion 20C. The magnitude of the force F4 per unit length divided by the longitudinal length L4 of the core side portion 20D is followed by a value (F4/L4), and the magnitude of the force F1 for extending the waist side portion 20A per unit length in the lateral direction is divided by the waist side portion The value (F1/L1) obtained by the longitudinal length L1 of 20A is the smallest.

This can prevent shrinkage of the waistline side portion 20A and suppress excessive shrinkage of the core side portion 20D in the lateral direction, while suppressing sagging of the absorptive main body 10 at the intermediate portion 20C. Therefore, the flatness of the absorber core 11A can be maintained so that a gap is hardly generated between the absorptive main body 10 and the wearer. Therefore, leakage of excrement can be suppressed.

Note that the method of measuring the forces F1 to F4 for extending the respective portions 20A to 20D of the waistline portion 20 by a unit length in the lateral direction may be a known method. For example, a target portion is cut from the diaper 1 as a sample. It is assumed that the sample includes the effective length portions of all the elastic threads 23 included in the respective portions 20A to 20D. Both ends of the sample corresponding to the transverse direction of the diaper 1 are clamped by chucks of a tensile tester such as Autograph (AGS-G100N) manufactured by SHIMADZU Corporation. Then, the load (N) obtained when the sample is stretched by separating the chuck per unit length can be used as the magnitude of the forces F1 to F4 that elongate the unit length in the transverse direction.

As shown in FIG. 5 , it is preferable that the waist side end 21 a of the inner layer sheet portion 21 is longitudinally positioned at the waist with respect to the elastic thread 23 a arranged on the most waist side among the plurality of elastic threads 23 included in the waist portion 20 . side. Similarly, it is preferable that the crotch side edge 21b of the inner layer sheet part 21 is located on the crotch side in the longitudinal direction with respect to the waist side edge 10a of the absorptive main body 10 .

Therefore, the inner layer sheet portion 21 can be provided on the skin side with respect to a larger number of waist side elastic threads 23a to 23e. Therefore, it is less likely that line marks due to more elastic threads 23a to 23e are generated on the waist of the wearer.

Although the inner layer sheet portion 21 is preferably provided on the skin side of all the waistline side elastic threads 23a to 23e as in the present embodiment ( FIG. 5 ), the present invention is not limited to this. The inner-layer sheet part 21 may be provided between at least one elastic thread 23 of the waist-side elastic threads 23 a to 23 e and the skin-side sheet part 221 .

===Modification of waist part 20 ===

6 to 9 are cross-sectional views of modified examples of the waist portion 20 .

The waist part 20 shown in FIG. 6 has a structure similar to that shown in FIG. 5 . Between the first sheet 21 and the second sheet 22 (non-skin side sheet portion 222 ), the elastic thread 23 is sandwiched and fixed, and the first sheet 21 corresponds to the inner layer sheet portion 21 . The first sheet 21 has a higher flexural stiffness than that of the skin-side sheet portion 221 . However, in FIG. 6 , the longitudinal waist side end portion 212 of the inner layer sheet portion 21 is folded toward the skin side together with the second sheet 22 .

Therefore, the unfolded portion 211 and the folded portion 212 of the inner layer sheet portion 21 are arranged on the skin side of the waistline side elastic threads 23a to 23e. The linear load of the waist-side elastic threads 23a to 23e is absorbed and relieved by the two inner layer sheet portions 211 and 212 . Therefore, the waist-side elastic threads 23a to 23e are less likely to bite into the waist of the wearer and are even less likely to produce thread marks on the waist of the wearer.

In the waist portion 20 shown in FIG. 7 , similarly to FIG. 5 , a portion of the second sheet 22 serves as the non-skin side sheet portion 222 , and a portion provided by folding the waist side end portion of the second sheet 22 serves as the skin Side panel portion 221 . However, in FIG. 7, regarding the first sheet 21 in which the elastic thread 23 is fixed by sandwiching the elastic thread 23 between the first sheet 21 and the second sheet 22 (non-skin side sheet portion 222), it is based on the KES method. The flexural rigidity (at least one of transverse flexural rigidity and longitudinal flexural rigidity) is 0.0096 N·m ² /m×10 ⁻⁴ or less. That is, the first sheet 21 and the skin-side sheet portion 221 are equally flexible sheets, and correspond to the second inner layer sheet portion.

Therefore, in the waist portion 20 shown in FIG. 7 , the inner layer sheet portion 24 is arranged between the second inner layer sheet portion 21 and the skin side sheet portion 221 . The inner layer sheet portion 24 is a sheet separate from the first sheet 21 and the second sheet 22 . The flexural rigidity of the inner layer sheet portion 24 is higher than the flexural rigidity of the skin-side sheet portion 221 . Therefore, the inner sheet portion 24 is less likely to cause line marks on the wearer's skin.

In the case of the waist portion 20 shown in FIG. 7 , the longitudinal length of the inner layer sheet portion 24 having high rigidity may be smaller than the longitudinal length of the first sheet 21 . Specifically, it is preferable that the longitudinal length of the inner-layer sheet portion 24 is such a length that the inner-layer sheet portion 24 can cover the waist-side elastic threads 23a to 23e from the skin side. Therefore, in the waist portion 20 shown in FIG. 7 , the range in which the inner layer sheet portion 24 having higher rigidity is arranged can be narrower than that in the waist portion 20 shown in FIG. 5 . The flexibility of the waist portion 20 can be increased.

In the waist portion 20 shown in FIG. 8 , with respect to the first sheet 21 in which the elastic thread 23 is fixed by sandwiching the elastic thread 23 between the first sheet 21 and the second sheet 22 (non-skin side sheet portion 222 ), the opposite The inner layer sheet part 25 is arranged on the skin side on the first sheet 21 . The inner layer sheet portion 25 is a sheet separate from the first sheet 21 and the second sheet 22 . The flexural rigidity of the inner-layer sheet portion 25 is higher than the flexural rigidity of the skin-side sheet portion 221 . The first sheet 21 corresponds to the third inner layer sheet portion 21 .

In FIG. 8, the configuration of the elastic thread 23 varies according to its longitudinal position. Specifically, the waist-side elastic threads 23 a to 23 e are arranged between the inner layer sheet portion 25 and the third inner layer sheet portion 21 in the thickness direction. In contrast, the core-side elastic wires 23f arranged in the core-side portion 20D are arranged between the third inner layer sheet portion 21 and the non-skin-side sheet portion 222 in the thickness direction. Likewise, the middle elastic thread 23g arranged in the middle portion 20C is preferably arranged between the third inner layer sheet portion 21 and the non-skin side sheet portion 222 in the thickness direction.

In this case, the waistline side elastic threads 23a to 23e are further arranged on the skin side, making it difficult to visually recognize from the outside (non-skin side) of the diaper 1 . Therefore, the user's waist side portion 20A can be given an impression of being softly fitted to the wearer's waist. In contrast, the core-side elastic thread 23f and the middle elastic thread 23g are further arranged on the non-skin side, so as to be easily visually recognized from the outside of the diaper 1 . This makes it possible to give an impression to the user that the absorbent core 11A and the absorbent main body 10 have high fit and little leakage due to the elastic threads 23 .

Since the flexural rigidity by the KES method of the inner layer sheet portion 25 is higher than the flexural rigidity of the skin side sheet portion 221 , line marks are less likely to be generated on the waist of the wearer. In particular, in this case, it is preferable to use the stretching force of the waistline side portion 20A (that is, a value obtained by dividing the magnitude of the force for extending the waistline side portion 20A per unit length in the lateral direction by the longitudinal length of the waistline side portion 20A). ) is smaller than the stretching force of the other parts 20C and 20D. Therefore, although the waist-side elastic threads 23a to 23e are located further on the skin side, it is unlikely that line marks are produced on the wearer's waist.

The stiffness of the third inner layer sheet portion 21 may be greater than the flexural stiffness of the skin-side sheet portion 221 , or may be equal to or less than the flexural stiffness of the skin-side sheet portion 221 . Although not shown, it is also possible to adopt a configuration in which a portion formed by folding the waist-side end portion of the first sheet 21 serves as an inner layer sheet portion ( 25 ) and an unfolded portion serves as a third inner layer sheet portion ( twenty one).

In the waist portion 20 shown in FIG. 9 , compared with the waist portion 20 shown in FIG. 8 , the inner layer sheet portion 25 extends toward the crotch side, and the number of the intermediate elastic threads 23g in the intermediate portion 20C is increased. Specifically, some of the intermediate elastic wires 23g are arranged between the inner layer sheet portion 25 and the third inner layer sheet portion 21 in the thickness direction, and other intermediate elastic wires 23g are arranged in the thickness direction of the third inner layer sheet portion 21 and the non-skin side panel portion 222 .

The intermediate portion 20C has elastic wires 23g arranged so as to overlap each other in the thickness direction so that the stretching force of the intermediate portion 20C (that is, the magnitude of the force to elongate the intermediate portion 20C per unit length in the lateral direction is divided by the longitudinal direction of the intermediate portion 20C). The value obtained by the length) is larger than the expansion and contraction force of the other parts 20A and 20D. This can prevent shrinkage of the waistline side portion 20A and suppress excessive shrinkage of the core side portion 20D in the lateral direction, while suppressing sagging of the absorptive main body 10 at the intermediate portion 20C. Therefore, the flatness of the absorptive core 11A can be maintained so that a gap is hardly generated between the absorptive main body 10 and the wearer. Therefore, leakage of excrement can be suppressed.

<Second Embodiment>

===Structure of the underpants-type disposable diaper 1 ===

Fig. 10 is a perspective view of a pants-type disposable diaper 1 (hereinafter, referred to as "diaper") according to the second embodiment. Fig. 11 is a plan view of the diaper 1 in an unfolded and extended state. FIG. 12 is a cross-sectional view taken along line I-I in FIG. 11 . Hereinafter, the configuration of the diaper 1 according to the second embodiment will be explained mainly from points different from the diaper 1 according to the first embodiment.

As shown in FIG. 12 , in the diaper 1 of the second embodiment, the abdominal waist portion 20 (the back waist portion 30 ) includes a first sheet 21 ( 31 ), a second sheet 22 ( 32 ), and a laterally expandable and contractible The plurality of elastic threads 23 (33). A plurality of elastic threads 23 ( 33 ) are arranged side by side in the longitudinal direction between the first sheet 21 ( 31 ) and the second sheet 22 ( 32 ), and are fixed in a state elongated in the lateral direction. Therefore, the abdominal waist part 20 and the back waist part 30 expand and contract in the lateral direction, and are fitted to the waist of the wearer. Suitable examples of the elastic threads 23 and 33 are styrene-based rubber, urethane-based rubber, ester-based rubber, and other known synthetic rubbers made of polyurethane or polyethylene, in addition to the natural rubber in the form of threads.

In the back side waist portion 30 , the elastic thread 33 is arranged in a region from the upper end portion to the lower end portion of the back side waist portion 30 . In contrast, the elastic thread 23 is not arranged in the upper end portion of the abdominal waist portion 20 . On the contrary, in the upper end part of the abdominal waist part 20, the elastic sheet 240 which can expand and contract in the lateral direction is arranged. In the longitudinal direction, the stretchable sheet 240 and the elastic thread 23 may be arranged in a manner of overlapping with each other or in a manner of being completely staggered from each other.

In the upper end portion of the abdominal waist portion 20, since the elastic sheet 240 is arranged without the elastic thread 23, the upper end portion of the abdominal waist portion 20 is in close ground contact with the wearer. Therefore, local shrinkage is suppressed and traces of the elastic members are less likely to be left. In particular, since the abdomen of the infant protrudes, it is preferable to suppress the contraction of the abdominal waist portion 20 .

When the wearer wears the diaper 1 , the ease of expansion and contraction of the waist opening BH is greatly influenced by the expansion and contraction force of the upper end portions of the waist portions 20 and 30 . The stretchable sheet 240 has a property of being easily stretched from a natural state and hardly shrinking from the stretched state. Since the elastic sheet 240 is arranged at the upper end of the abdominal waist portion 20, the waist opening BH is easily expanded when the wearer wears the diaper 1, and the diaper 1 can prevent the diaper 1 from pinching the abdomen after the waist portion 20 is fitted to the wearer.

Examples of the stretchable sheet 240 include a nonwoven fabric or a stretchable plastic film that has undergone a suitable stretching treatment (such as gear stretching, etc.), which includes a polyurethane-based elastomer and polypropylene (PP), which is a The elastomer is an elastic thermoplastic elastomer fiber, and the polypropylene (PP) is a non-elastic thermoplastic resin fiber and a polyolefin-based resin.

In the diaper 1 according to the present embodiment, only the abdominal waist portion 20 includes the elastic sheet 240, but it is not limited to this. Both the abdominal waist portion 20 and the back waist portion 30 may include the elastic sheet 240 . Alternatively, the abdominal waist portion 20 may not include the stretchable sheet 240 , and only the back waist portion 30 may include the stretchable sheet 240 .

===Characteristic part of the abdominal waist part 20 ===

13A is a schematic cross-sectional view showing the contracted state of the skin side sheet portion 400 according to the comparative example, and FIG. 13B is a schematic cross-sectional view showing the contracted state of the skin side sheet portion 221 according to the present embodiment. FIG. 14 is an enlarged view of a cross-sectional view of the abdominal waist portion 20 shown in FIG. 12 .

At least one of the pair of waist portions 20 and 30 included in the diaper 1 according to the present embodiment has the following characteristic parts. Hereinafter, the ventral waist portion 20 will be described as an example; however, the dorsal waist portion 30 does not necessarily have the following characteristic parts. Alternatively, both the ventral waist portion 20 and the dorsal waist portion 30 may have the following features; or the dorsal waist portion 30 alone may have the following features while the ventral waist portion 20 does not have the following features part.

The abdominal waist portion 20 (hereinafter, also simply referred to as “waist portion 20 ”) includes the first sheet 21 , the second sheet 22 , the plurality of elastic threads 23 , and the stretchable sheet 240 as described above. A part of the second sheet 22 serves as a non-skin side sheet portion 222 that is a portion arranged at a position on the most non-skin side of the waist portion 20 . The longitudinal waist side end portion of the second sheet 22 is folded toward the skin side and is located on the skin side with respect to the absorbent main body 10 . This folded portion serves as the skin-side panel portion 221 arranged at the most skin-side position of the waist portion 20 .

The first sheet 21 is arranged between the non-skin side sheet portion 222 and the absorptive main body 10 in the thickness direction. The plurality of elastic threads 23 are arranged between the non-skin side sheet portion 222 and the first sheet 21 in the thickness direction. The stretchable sheet 240 is arranged between the skin-side sheet portion 221 and the absorptive main body 10 in the thickness direction. Materials adjacent to each other in the thickness direction are bonded with the adhesive 50 shown in FIG. 14 .

Since the skin side sheet portion 221 is in direct contact with the wearer's skin at the waist portion 20, the skin side sheet portion 221 is a soft sheet with low flexural rigidity. This can improve the feel of the skin side panel portion 221 on the wearer's skin.

Specifically, as a result of the test conducted by the inventors, it was found that the flexural rigidity by the KES method of the skin side panel portion 221 is preferably 0.0096 N·m ² /m×10 ⁻⁴ or less. Generally, the waist portion 20 of the diaper 1 is provided with elastic members (elastic sheets 240 and elastic threads 23) that expand and contract in the lateral direction so as to fit to the waist of the wearer. The waist portion 20 is contracted in the lateral direction by the elastic member, and irregularities are formed in the thickness direction, and the irregularities are located in the waist portion 20 side by side in the lateral direction. The unevenness is long in the longitudinal direction; in other words, longitudinal pleats are formed in the waist portion 20 .

Therefore, in the case where the flexural stiffness of the skin-side sheet portion 400 is greater than 0.0096 N·m ² /m×10 ⁻⁴ and the skin-side sheet portion 400 has high The portion 400 is formed with large and uniform unevenness, as in the comparative example shown in FIG. 13A . Furthermore, the shape retention (resilience) of the protruding portion 410 protruding toward the skin side is improved. When the skin side panel portion 400 is in contact with the wearer, the protrusions 410 are hardly crushed, and the protrusions 410 may bite deeply into the wearer's skin. As a result, longitudinal creases (indentations formed by protrusions 410 ) may be created on the wearer's skin.

In contrast, according to the present embodiment, the flexural rigidity of the skin side panel portion 221 is set to be 0.0096 N·m ² /m×10 ⁻⁴ or less. As the skin-side sheet portion 221, a sheet having high drapeability and hanging down loosely is used. Therefore, as shown in FIG. 13B , in the skin-side sheet portion 221, uneven unevenness having repeated fine undulations is formed due to the contraction of the elastic member. That is, the skin side panel portion 221 is smooth, and the contact area between the skin side panel portion 221 and the wearer's skin can be increased. Therefore, the contact pressure of the skin-side sheet portion 221 due to the elastic member can be dispersed, thus suppressing the large protrusions 410 according to the comparative example such as shown in FIG. 13A from locally contacting the wearer's skin. Furthermore, the shape retention (resilience) of the protruding portion 250 protruding to the skin side decreases. Therefore, when the skin side panel portion 221 is in contact with the wearer, the protrusions 250 may be crushed, and the protrusions 250 are less likely to bite into the wearer's skin. This results in virtually no vertical creases on the wearer's skin. Therefore, at least one of the lateral flexural rigidity and the longitudinal flexural rigidity of the skin side panel portion 221 needs to be 0.0096 N·m ² /m×10 ⁻⁴ or less. Preferably, the transverse flexural stiffness, which largely affects the formation of wrinkles, is 0.0096 N·m ² /m×10 ⁻⁴ or less. More preferably, the flexural stiffness in both directions is 0.0096 N·m ² /m×10 ⁻⁴ or less.

In the longitudinal waist side end portion of the absorbent main body 10, a plurality of materials are laminated on each other and an adhesive is applied. This end may be stiff. Therefore, the longitudinal waist side end edge 10a of the absorbent body 10 (ie, the edge in the step between the portion with the absorbent body 10 and the portion without the absorbent body 10) may bite into the wearer's skin. Concavity and convexity are also formed in the edge 10a of the absorptive main body 10 due to the shrinkage of the elastic member. However, the protrusions of the end edge 10a of the absorbent body are relatively stiff and less likely to be crushed, so the protrusions may locally bite into the skin of the wearer. In many cases, the waist of an infant to whom the diaper 1 according to the present embodiment is worn protrudes. The edge 10a of the absorptive main body 10 may bite into the waist of an infant whose waist protrudes.

In the waist part 20 shown in FIG. 14, on the skin side of the absorptive main body 10, the skin side sheet part 221 is arrange|positioned over the edge 10a of the absorptive main body 10. However, the flexural rigidity of the skin-side sheet portion 221 is as low as 0.0096 N·m ² /m×10 ⁻⁴ or less, and the cushioning properties of the skin-side sheet portion 221 are low. Therefore, the hardness and step of the edge 10a of the absorptive main body 10 are less likely to be absorbed and relieved by the skin side sheet portion 221 . Therefore, for example, when only the skin side sheet portion 221 is arranged on the skin side with respect to the end edge 10a of the absorptive main body 10, the end edge 10a of the absorptive main body 10 bites into the skin of the wearer, causing marks on the skin, etc., And the marks may damage the wearer's skin.

Therefore, in the diaper 1 according to the present embodiment, the elastic sheet 240 as the inner layer sheet portion is arranged on the non-skin side with respect to the skin side sheet portion 221, and the flexural rigidity of the elastic sheet 240 by the KES method is made high than (greater than) the flexural stiffness of the skin side panel portion 221 . The stretchable sheet 240 is provided on the skin side of the absorptive main body 10 so as to straddle the longitudinal waist side edge 10 a of the absorptive main body 10 . That is, the elastic sheet 240 covers the edge 10a of the absorptive main body 10 from the skin side.

Therefore, the elastic sheet 240 having higher cushioning properties than that of the skin-side sheet portion 221 is arranged on the skin side with respect to the edge 10a of the absorptive main body 10, and the hardness and hardness of the edge 10a of the absorptive main body 10 are alleviated by absorption. steps. Therefore, the edge 10a of the absorptive main body 10 is less likely to bite the wearer's skin, the wearer's skin can be suppressed from being damaged by the edge 10a of the absorptive main body 10, and the skin side surface of the waist portion 20 can be improved on the skin touch. Note that it is only necessary to make at least one of the lateral flexural rigidity and the longitudinal flexural rigidity of the elastic sheet 240 (inner layer sheet portion) higher than at least one of the lateral flexural rigidity and longitudinal flexural rigidity of the skin side sheet portion 221 high.

As described above, in the diaper 1 according to the present embodiment, it is unlikely that the wrinkles of the longitudinal gathers and the traces of the edge 10a of the absorptive main body 10 are generated in the waist of the wearer. Therefore, the sensitive skin of infants and young children can be inhibited from being damaged. In addition, the stretchable sheet 240 having higher rigidity is not located at the most skin-side position, but the skin-side sheet portion 221 softer than the inner layer sheet portion 21 is located at the most skin-side position. A good feel on the wearer's skin can be maintained.

The flexural rigidity of the skin-side sheet portion 221 is more preferably 0.007 N·m ² /m×10 ⁻⁴ or less. Therefore, it is less likely that longitudinal fold marks will be created on the waist of the wearer. The flexural rigidity of the inner layer sheet portion (stretchable sheet 240 in FIG. 14 ) is preferably 0.0096 N·m ² /m×10 ⁻⁴ or more, or more preferably 0.015 N·m ² /m×10 ⁻⁴ or more. Alternatively, the flexural stiffness of the inner-layer sheet portion may be more than twice that of the skin-side sheet portion 221, or the difference between the flexural stiffnesses of the two sheet portions may be 0.005 N·m ² /m×10 ^-4 and above. This makes it less likely that the end edge 10a of the absorbent body 10 will damage the wearer's skin.

In addition, in the waist portion 20 shown in FIG. 14 , a portion formed by folding the longitudinal waist side end of the second sheet 22 (of the non-skin side sheet portion 222 ) toward the skin side is used as the skin side sheet portion 221 . Therefore, like the skin-side sheet portion 221, the non-skin-side sheet portion 222 has a flexural rigidity by the KES method of 0.0096 N·m ² /m×10 ^-4 or less, and thus is a soft sheet. This makes it possible to improve the feel of the waist portion 20 on the non-skin side. In particular, in the case of the diaper 1 for infants, since the infant caregiver or the like does not wear the diaper 1, the infant caregiver or the like can hardly feel the good touch of the waist portion 20 on the skin side. The improvement of the feel of the waist portion 20 on the non-skin side can give an impression to the caregivers of infants and the like that the diaper 1 is a product with a good feel.

However, the present invention is not limited to the configuration of the waist portion 20 shown in FIG. 14 . For example, the skin side panel portion 221 and the non-skin side panel portion 222 may be formed from separate sheets. The flexural rigidity of the non-skin side panel portion 222 is not limited to 0.0096 N·m ² /m×10 ⁻⁴ or less. The flexural rigidity of the first sheet 21 is not particularly limited, and may be 0.0096 N·m ² /m×10 ⁻⁴ or less, or may be higher than 0.0096 N·m ² /m×10 ⁻⁴ .

In the waist part 20 shown in FIG. 14, the elastic thread 23 is arrange|positioned between the non-skin side panel part 222 and the 1st panel 21. As shown in FIG. In contrast, the stretchable sheet 240 is arranged between the skin side sheet portion 221 and the absorptive main body 10 . Therefore, by using the elastic sheet 240 to make the waist part 20 come into close contact with the wearer's ground, it is possible to absorb and alleviate the stiffness and the step of the edge 10a of the absorptive main body 10 . Therefore, in the case of the waist portion 20 shown in FIG. 14 , the structure can be simplified compared to the case where a material for absorbing and relaxing the hardness and the step of the edge 10 a of the absorptive main body 10 is provided in addition to the elastic sheet 240 . .

Note that the flexural rigidity of the skin side sheet portion 221 based on the KES method and the inner layer sheet portion (stretchability and elasticity) can be measured by using a measuring tester (pure bending tester KES-FB2-AUTO-A manufactured by Kato Tech Co., Ltd.). Flexural stiffness based on the KES method of sheet 240). Specifically, both the skin side sheet portion 221 and the inner layer sheet portion were cut into pieces of 10 cm×10 cm used as samples. Then, each sample was fixed between the chucks of the measuring testing machine so that the flexural stiffness of the sample in the transverse direction could be measured. Each sample was bent anteriorly to a maximum curvature of +2.5cm" ¹ , and inwardly to a maximum curvature of -2.5cm" ¹ , and then returned to its original position. The flexural stiffness value was calculated from the average value of the inclination when the inclination of the bending moment with respect to the curvature was substantially constant after starting the forward bending and the inclination when the inclination of the bending moment with respect to the curvature was substantially constant after starting the inward bending . The measurement was repeated five times for each sample, and the average of the obtained values was used as the flexural stiffness. The flexural rigidity (described later) of other sheet portions can also be measured in the same manner.

The crotch side edge 240a of the elastic sheet 240 is preferably located on the waist side in the longitudinal direction with respect to the waist side edge 11Aa of the absorptive core 11A. That is, it is preferable that the elastic sheet 240 does not overlap with the absorptive core 11A in the thickness direction. Therefore, excessive shrinkage of the absorptive core 11A in the lateral direction due to the stretchable sheet 240 can be suppressed. The flatness of the absorptive core 11A can be maintained. Therefore, a gap is less likely to be generated between the absorptive main body 10 and the wearer, and leakage of excrement can be suppressed. Also, deterioration of wearing comfort can be suppressed.

Although the flexural rigidity of the skin side sheet portion 221 is low, it is also preferable to arrange the skin side sheet portion 221 on the skin side of the absorptive main body 10 across the end edge 10a of the absorptive main body 10 like the elastic sheet 240 . Therefore, the hardness and the level|step difference of the edge 10a of the absorptive main body 10 are absorbed by the skin side sheet part 221 and the elastic sheet 240, and are relieved. Therefore, compared with the case where only the elastic sheet 240 is arranged on the skin side of the end edge 10a of the absorptive body 10, the wearer's skin can be further suppressed from being damaged by the end edge 10a of the absorptive body 10.

In addition, in the longitudinal direction, the crotch side edge 221a of the skin side panel portion 221 extends further toward the rail side than the crotch side edge edge 240a of the elastic sheet 240, so that the elastic sheet 240 can be firmly fixed to the skin side panel portion 221 . Therefore, curling of the elastic sheet 240 is suppressed.

===Modification of waist part 20 ===

15 to 17 are cross-sectional views of modified examples of the waist portion 20 .

In the waist portion 20 shown in FIG. 15 , similarly to FIG. 14 , a part of the second sheet 22 serves as the non-skin side sheet portion 222 , and a portion formed by folding the waist side end of the second sheet 22 serves as the skin Side panel portion 221 . In FIG. 15, the first sheet 21 fixes the elastic thread 23 by sandwiching the elastic thread 23 between the first sheet 21 and the second sheet 22 (non-skin side sheet portion 222), and the first sheet 21 corresponds to the inner layer film department. The first sheet 21 has a higher flexural stiffness than that of the skin-side sheet portion 221 .

The inner layer sheet part 21 (first sheet) includes a skin side part 211 and a non-skin side part 212; the skin side part 211 is a part formed by folding the longitudinal waist side end part toward the skin side of the absorptive main body 10, and the non-skin side part 211 is The side portion 212 is a portion arranged on the non-skin side with respect to the skin side portion 211 . The skin side part 211 of the inner layer sheet part 21 is arranged on the skin side of the absorptive main body 10 , spanning the longitudinal waist side edge 10 a of the absorptive main body 10 . Therefore, the hardness and step of the edge 10a of the absorptive main body 10 are absorbed and relieved by the skin side portion 211 of the inner layer sheet part 21, and the wearer's skin can be prevented from being damaged by the edge 10a of the absorptive main body 10.

When the elastic thread 23 (stretchable member) is arranged between the non-skin side portion 212 and the non-skin side sheet portion 22 of the inner layer sheet portion 21 in the thickness direction, the stretchable sheet 240 (stretchable sheet portion) in the thickness direction The upper is disposed between the skin side portion 211 and the non-skin side portion 212 of the inner layer sheet portion 21 . In this case, the flexural rigidity of the stretchable sheet 240 based on the KES method is preferably higher than the flexural rigidity of the skin side sheet portion 221 , and the stretchable sheet 240 is preferably arranged so as to span the end edge 10 a of the absorptive main body 10 On the skin side of the absorbent body 10 .

Therefore, the hardness and step of the edge 10a of the absorbent body 10 are absorbed and moderated by the two-layer sheet portion having high rigidity, that is, they are absorbed and moderated by the skin side portion 211 and the elastic sheet 240 of the inner sheet portion 21 . Therefore, the wearer's skin can be further suppressed from being damaged by the edge 10a of the absorptive main body 10 .

When a plurality of sheet portions other than the skin-side sheet portion 221 are arranged on the skin side of the end edge 10a of the absorbent main body 10 as shown in FIG. 15 , the flexural rigidity of at least one such sheet portion needs to be higher than the skin side The flexural stiffness of the sheet portion 221 . In the waist portion 20 of FIG. 15 , the flexural rigidity of the skin-side portion 211 of the inner layer sheet portion 21 may be equal to or smaller than the flexural rigidity of the skin-side sheet portion 221 . In addition, the flexural rigidity of the stretchable sheet 240 may be equal to or smaller than the flexural rigidity of the skin-side sheet portion 221 . In this case, the stretchable sheet 240 may be disposed between the non-skin side sheet portion 222 and the non-skin side portion 212 of the inner layer sheet portion 21 .

The absorptive core 11A is a thick member, and the absorptive core 11A has high rigidity. Therefore, it is preferable that the longitudinal waist side edge 11Aa of the absorptive core 11A does not reach the waist side edge 10a of the absorptive main body 10 . When the absorptive core 11A is covered with the core wrap sheet 11B, the waist side edge (not shown) of the core wrap sheet 11B preferably does not reach the end edge 10a of the absorptive main body 10 . Therefore, the hardness and the step of the edge 10a of the absorptive main body 10 can be suppressed from being increased by the absorptive core 11A and the core wrapping sheet 11B. Therefore, the edge 10a of the absorptive main body 10 can be as soft as possible, and the wearer's skin can be suppressed from being damaged by the edge 10a of the absorptive main body 10.

It is preferable that the crotch side edge 211a of the skin side part 211 of the inner layer sheet part 21 is located on the crotch side in the longitudinal direction with respect to the waist side edge 11Aa of the absorptive core 11A. Therefore, the hardness and the step of the edge 11Aa of the absorptive core 11 are absorbed and relieved by the skin side part 211 of the inner layer sheet part 21 . Therefore, the wearer's skin can be further suppressed from being damaged by the edge 11Aa of the absorptive core 11A.

14, the crotch side edge 240a of the elastic sheet 240 is preferably located on the waist side in the longitudinal direction with respect to the waist side edge 11Aa of the absorptive core 11A. Therefore, excessive shrinkage of the absorptive core 11A in the lateral direction due to the stretchable sheet 240 can be suppressed. The flatness of the absorptive core 11A can be maintained.

The waist portion 20 shown in FIGS. 16 and 17 is different from the waist portion 20 shown in FIG. 15 in the length of the skin side panel portion 221 in the longitudinal direction, and other structures are the same as each other. Similar to the waist part 20 shown in FIG. 17 , the crotch side end 221 a of the skin side panel part 221 may be located on the waist side with respect to the edge 10 a of the absorbent main body 10 .

Similar to the waist portion 20 shown in FIGS. 15 and 16 , the skin side panel portion 221 may be arranged on the skin side of the absorbent body 10 across the end edge 10 a of the absorbent body 10 . In this case, although the flexural rigidity of the skin-side sheet portion 221 is low, the hardness and step of the edge 10 a of the absorptive main body 10 are absorbed and relaxed by the skin-side portion 211 and the skin-side sheet portion 221 of the inner-layer sheet portion 21 . . Therefore, the wearer's skin can be further suppressed from being damaged by the edge 10a of the absorptive main body 10 .

In the waist portion 20 shown in FIG. 15 , the longitudinal length of the skin-side sheet portion 221 is equal to the longitudinal length of the skin-side portion 211 of the inner layer sheet portion 21 . In the case of the waist portion 20 shown in FIGS. 16 and 17 , the longitudinal length of the skin-side sheet portion 221 is smaller than the longitudinal length of the skin-side portion 211 of the inner-layer sheet portion 21 . As described above, in the case where the crotch side end 221a of the skin side sheet portion 221 does not coincide with the crotch side end 211a of the skin side portion 211 of the inner layer sheet portion 21 in the longitudinal direction, the same as the plurality of sheets shown in FIG. 15 Compared with the case where the crotch side ends of the parts are aligned with each other, the steps at the crotch side ends of the respective panel parts can be reduced. Therefore, the wearer's skin can be suppressed from being damaged by the crotch side end of each panel. In addition, since the number of stacked layers of the sheet portion is changed one by one in the longitudinal direction, discomfort during use can be reduced.

Likewise, it is preferable that the crotch side edge 240a of the elastic sheet 240 does not coincide with the crotch side edge 211a of the skin side part 211 of the inner layer sheet part 21 and the crotch side edge 221a of the skin side part 221 in the longitudinal direction. Therefore, the wearer's skin can be restrained from being damaged by the crotch side end of each sheet portion, and discomfort during use can be reduced.

When the crotch side end of each sheet portion is displaced, it is preferable that the crotch side end edge 211a of the skin side portion 211 of the inner layer sheet portion 21 is positioned at the most rail side in the longitudinal direction. Therefore, the skin-side sheet portion 221 and the elastic sheet 240 can be firmly fixed to the skin-side portion 211 of the inner-layer sheet portion 21 . This can suppress the following phenomenon: the skin side panel part 221 having low rigidity is located at the most crotch side, and the crotch side end of the skin side panel part 221 is twisted; The crotch side end of the sexual sheet 240 is curled.

Although not shown, waist side end portions of the stretchable sheet 240 may be folded together with the first sheet 21 and the second sheet 22 and positioned on the skin side and the non-skin side of the absorbent main body 10 . In the case of the waist portion 20 shown in FIGS. 15 to 17 , the elastic thread 23 may be arranged at the upper end portion of the waist portion 20 instead of the elastic sheet 240 . The stretchable sheet 240 may be arranged in a part or all of the waist portion 20 without being limited to the upper end portion of the waist portion 20 .

===Flexibility of the skin side panel portion 221 according to each of the first embodiment and the second embodiment ===

As described above, in order to improve the feel of the waist portion 20 on the wearer's skin and make it less likely that longitudinal folds are formed on the wearer's skin, the skin side panel portion 221 is highly flexible (has high drape) Sheet. Next, the structure of the skin side panel portion 221 will be described. The non-skin side panel portions 222 preferably have the same flexibility.

For the skin side sheet portion 221, a nonwoven fabric which is made of fibers containing thermoplastic synthetic resin and is a spunbond fiber nonwoven fabric is used. More preferably, spunbond fiber nonwovens or spunbond-meltblown-spunbond (SMS) fiber nonwovens are preferably used. As continuous fibers constituting such a nonwoven fabric, polyolefin-based thermoplastic fibers containing polypropylene (PP) and polyethylene (PE), which are various types of known synthetic resins, are preferably used. In this embodiment, a spunbond fiber nonwoven fabric mainly containing polyethylene fibers is used.

Since the skin side panel portion 221 is formed of a spunbond nonwoven fabric formed of continuous fibers, the free ends of the fibers do not come into direct contact with the wearer's skin, unlike an airlaid nonwoven fabric or the like including short fibers. In particular, when the wearer makes contact with the fingertips, the relatively free-moving continuous fibers are in contact with the fingerprints of the fingers, while the free ends of the fibers are not in contact with the fingerprints, thereby providing a soft and delicate texture to the skin. Unlike the case of using conjugate fibers or the like, a step of fibrillating fibers is not required. The number of manufacturing steps is small and the manufacturing cost can be reduced.

Since the spunbond fiber nonwoven fabric or SMS fiber nonwoven fabric composed of continuous fibers is used for the skin side sheet portion 221, no fluff occurs on the surface of the sheet material, and compared with other synthetic fibers composed of short fibers, the Can give the wearer a smooth, flexible, soft feel. In addition, the fiber orientation of spunbond fiber nonwovens is easier to control than other fiber nonwovens. Therefore, the complex waist portion 20 having a desired balance of sheet tensile strength and stretchability can be obtained.

The skin side sheet portion 221 is a fibrous nonwoven fabric mainly containing polyethylene fibers. The percentage content of polyethylene fibers relative to the entire sheet is 70% by mass to 100% by mass. Since polyethylene fibers are softer than other thermoplastic resin fibers such as polypropylene fibers and PET (polyethylene terephthalate) fibers, when the percentage content of polyethylene fibers is at least 70% by mass, it is Compared with the prior art non-woven fabrics with a percentage content of 70 mass% or less, the fibers are softer. In addition, polyethylene fibers have a larger fiber diameter, so the gaps between the fibers are larger and have high air permeability. Therefore, the water retention in the waist part 20 can be reduced.

When the skin side sheet portion 221 is formed of a spunbonded nonwoven fabric using continuous polyethylene fibers, the continuous fibers have a plurality of fused portions formed by thermally fusing the continuous fibers with each other by heat treatment by a calendar emboss method. In the fusion portion, each constituent fiber is thermally fused and the fiber shape is not maintained, and a part thereof is converted into a film. Therefore, the fused portion has a higher stiffness than the non-fused portion constituting the fiber.

The total area ratio of the fusion portion to the area of the skin-side sheet portion 221 is related to the texture of the sheet and the strength of the sheet. In view of this, the total area ratio of the fusion portion is preferably 5% or more and 25% or less. When the total area ratio is less than 5%, the strength of the sheet may decrease, and a part of the waist portion 20 may be broken during use. In contrast, when the total area ratio is more than 25%, the entire sheet may become hard and the texture may be deteriorated.

The flexibility (specifically, "smoothness" and "flexibility and flexibility") of the skin-side sheet portion 221 can be checked by using the surface properties, bending properties, fiber density, fiber diameter, specific volume, compression properties, and the like of the skin-side sheet portion 221 . softness").

The basis weight (weight per unit area) of the skin side sheet portion 221 is 10 g/m ² or more and 30 g/m ² or less, or more preferably 12 g/m ² or more and 25 g/m ² or less. The thickness under a light load (0.49 hPa) is preferably 0.10 mm or more and 0.60 mm or less. When the basis weight of the skin-side sheet portion 221 is less than 10 g/m ² , flexibility is high, but it is difficult to obtain sufficient tensile strength. When the basis weight exceeds 30 g/m ² , higher tensile strength can be obtained, however, it is difficult to obtain sufficient flexibility.

The apparent density of the skin side sheet portion 221 under a load of 0.49 hPa (≈0.5 gf/cm ² ) is 0.02 g/cm ³ or more and 0.1 g/cm ³ or less, or preferably 0.04 g/cm ³ or more and 0.08 g/cm ³ or less. The apparent density under a load of 49.03 hPa is 0.1 g/cm ³ or more and 0.2 g/cm ³ or less, or preferably 0.12 g/cm ³ or more and 0.18 g/cm ³ or less. The specific volume of the skin side sheet portion 221 under a load of 0.49 hPa is 10 cm ³ /g or more and 50 cm ³ /g or less, or preferably 12.0 cm ³ /g or more and 18.0 cm ³ /g or less. The specific volume under a load of 49.03 hPa is 5.0 cm ³ /g or more and 10 cm ³ /g or less, or preferably 4.0 cm ³ /g or more and 8.0 cm ³ /g or less.

When the apparent density of the skin-side sheet portion 221 under a load of 0.49 hPa is less than 0.02 g/cm ³ , the fusion portion of the skin-side sheet portion 221 decreases, and fluff may occur. In contrast, when the apparent density under a load of 0.49 hPa exceeds 0.1 g/cm ³ , the stiffness of the skin side panel portion 221 is relatively increased.

When the specific volume of the skin side panel part 221 under a load of 49.03 hPa (≈50 gf/cm ² ) is within a predetermined range and the fibers are compressed by pressing with fingertips, since the fibers are easily crushed and have a low recoil The elasticity and therefore the density increases, the contact area between the fingertip and the fibers is relatively increased, the fibers are easily attached to the fingertips and thus give the fingertips a soft feel and are less likely to create creases on the fibers.

The basis weight of the skin side sheet part 221 is measured according to the JISL1096 method. The apparent density was obtained using an average value (N=3) calculated from the basis weight and thickness obtained by measurement. The specific volume of the skin-side sheet portion 221 is calculated by dividing the basis weight of the nonwoven fabric by the thickness of the nonwoven fabric.

The average fiber diameter of the constituent fibers (mainly polyethylene fibers) of the skin side sheet portion 221 is 14 μm or more and 22 μm or less. Since the fiber diameter is large, the total area ratio of the fusion portion to the area of the skin side panel portion 221 is relatively small. This can reduce the flexural rigidity of the skin side panel portion 221 .

<Bending characteristics>

As described above, the flexural rigidity of the skin side panel portion 221 by the KES method is 0.0096 N·m ² /m×10 ⁻⁴ or less. This makes the fibers easier to bend, increases the contact distance between the fibers and the fingertips that touch the fibers, and increases the coefficient of friction MIU. As described above, the flexural rigidity of the skin side panel portion 221 by the KES method is preferably 0.0035 N·m ² /m×10 ⁻⁴ or more. In the case where the flexural rigidity is less than 0.0035 N·m ² /m×10 ⁻⁴ , there is a risk that the tensile strength of the skin side panel portion 221 is lowered and a part of the waist portion 20 is broken during use. As a result, the coefficient of change MMD/MIU×100 of the friction coefficient is 2% or more and 6% or less, so the change in the friction coefficient is reduced and the skin side sheet portion 221 becomes smoother. That is, the amount of fibers attached to the fingerprints of the fingertips is increased, giving a smooth feeling.

<Compression Properties>

The compressive work load WC by the KES method of the skin side panel portion 221 is preferably 0.14 N·m/m ² or more and 0.2 N·m/m ² or less, and the compression recovery rate RC is preferably 15% or more and 50% or less. In the case where the compressive working load WC is greater than 0.2 N·m/m ² , when the waist portion 20 comes into contact with the wearer, the protrusions 26 , 250 formed by the shrinkage of the waist portion 20 are less likely to be crushed, and there is a May bite into wearer's skin. When the compression recovery rate RC is greater than 50%, when the waist portion 20 comes into contact with the wearer, the crushed protrusions 26, 250 have a strong force to return to the original state, and the protrusions 26, 250 are worn increased local contact pressure on the patient's skin. In contrast, when the compressive work load WC is less than 0.14 N·m/m ² or when the compression recovery rate RC is less than 15%, the stiffness of the waist portion 20 is too low, and a part of the waist portion 20 is used may break during this time. By setting the compressive work load WC and the compressive recovery rate RC of the skin side panel portion 221 within the above-mentioned ranges, it is less likely that creases are generated in the waist of the wearer, while the tensile strength of the waist portion 20 is appropriately obtained.

<Surface Properties>

The skin side sheet portion 221 is a fiber web formed by thermally fusing continuous fibers mainly composed of polyethylene fibers to each other. Since there are no free ends of fibers on the surface, the amount of fluff is small and the sheet surface has good smoothness. Furthermore, polyethylene fibers are soft compared to polypropylene fibers. Polyethylene fibers have a soft surface that deforms under light loading and, as the wearer's body moves, follows and conforms to that movement.

The friction coefficient MIU of the surface of the skin side sheet portion 221 is 0.15 or more and 0.40 or less, more preferably 0.25 or more and 0.35 or less, and the average deviation MMD of the friction coefficient is 0.008 or more and 0.01 or less. Since the friction coefficient MIU exceeds 0.15, the frictional resistance is high. When the wearer contacts the surface of the sheet, the wearer may experience a smooth sensation such as fibers adhering to the wearer's skin. The coefficient of variation MMD/MIU×100 of the friction coefficient is 2.0% or more and 6.0% or less. As described above, when the compression recovery rate RC is less than 50%, the fibers are crushed and the fiber density increases even under a slight load applied when the wearer's fingertips are in contact with the fibers. The amount of fibers in contact with the fingertips increases, and the coefficient of friction MIU increases. Therefore, the coefficient of variation MMD/MIU×100% of the friction coefficient falls within the range of the smaller predetermined value. The variation in the coefficient of friction is reduced, providing adequate smoothness overall, a greater amount of fibers in contact with the user's fingertips in a manner that adheres to fingerprints, and can impart a smooth, pliable, and soft feel to the wearer.

The range of predetermined values of the curvature characteristics and surface characteristics of the skin side panel portion 221 may be satisfied in at least one of the lateral direction and the longitudinal direction of the waist body portion 20, or more preferably in both directions. The measurement of each mechanics based on the KES method in this specification is explained in detail in "Standardization and Analysis of Style Evaluation" 2nd Edition (Committee on Style Evaluation and Standardization of the Japan Textile Machinery Society, published on July 10, 1980).

Referring to Table 1, various nonwoven fabrics were produced under various conditions, and their properties and performance were evaluated. The nonwoven fabrics of Examples 1 to 5 were formed of spunbond nonwoven fabrics containing 100% by mass of polyethylene fibers as continuous fibers. The nonwoven fabric of Comparative Example 1 was formed of a spunbonded nonwoven fabric containing 100% by mass of polypropylene fibers as continuous fibers. Furthermore, in the manufacturing step, the nonwoven fabrics of Examples 1 to 5 and Comparative Examples 1 and 2 were heat-treated by a calendering method using a hot embossing roll.

The test subjects wore the diaper 1 having the skin side panel portion 221 using the nonwoven fabrics of Examples 1 to 5 and Comparative Examples 1 to 3, respectively, on infants and young children, and evaluated the possibility of wrinkle marks and stretching in two steps. strength. According to the skin of the infant after putting on the diaper, "○" was selected for the diaper that the test subject felt "less likely to form wrinkles", and "×" was selected for the test subject who felt "probable to develop creases" diapers 1. Regarding the tensile strength, “◯” was selected for the diaper 1 in which the waist portion 20 was broken in use, and “×” was selected for the diaper 1 in which the waist portion 20 was not broken.

Table 1

<Example 1>

For the nonwoven fabric of Example 1, a spunbonded nonwoven fabric composed of polyethylene fibers having a basis weight of 20.40 g/m ² and an average fiber diameter of 14.83 μm was used.

<Example 2>

For the nonwoven fabric of Example 2, a spunbonded nonwoven fabric composed of polyethylene fibers having a basis weight of 18.98 g/m ² and an average fiber diameter of 16.89 μm was used.

<Example 3>

For the nonwoven fabric of Example 3, a spunbonded nonwoven fabric composed of polyethylene fibers having a basis weight of 20.84 g/m ² and an average fiber diameter of 20.28 μm was used.

<Example 4>

For the nonwoven fabric of Example 4, a spunbonded nonwoven fabric composed of polyethylene fibers having a basis weight of 25.12 g/m ² and an average fiber diameter of 16.77 μm was used.

<Example 5>

For the nonwoven fabric of Example 5, a spunbond nonwoven fabric composed of polyethylene fibers having a basis weight of 15.14 g/m ² and an average fiber diameter of 16.77 μm was used.

<Comparative Example 1>

For the nonwoven fabric of Comparative Example 1, a spunbonded nonwoven fabric composed of polypropylene fibers having a basis weight of 20.37 g/m ² and an average fiber diameter of 12.19 μm was used.

<Comparative Example 2>

For the nonwoven fabric of Comparative Example 2, a spunbonded nonwoven fabric composed of conjugate fibers having a basis weight of 15.08 g/m ² and an average fiber diameter of 17.35 μm was used. As the conjugate fiber, continuous fibers and core-sheath type conjugate fibers including a core made of polypropylene and a sheath made of polyethylene are used.

<Comparative Example 3>

For the nonwoven fabric of Comparative Example 3, an air-permeable nonwoven fabric composed of conjugate fibers having a basis weight of 23.52 g/m ² and an average fiber diameter of 16.64 μm was used. For the conjugate fiber, a core-sheath type conjugate fiber, which is a short fiber having a fiber length of 51 mm and including a core made of polyethylene terephthalate (PET) and a core made of polyethylene terephthalate (PET), was used. Sheath made of vinyl.

The basis weight, fiber diameter, surface properties (MIU, MMD, MMD/MIU), bending properties (B), and compressive properties (T0, Tm, WC, RC) of each nonwoven fabric were measured by the following methods.

<Measurement method of basis weight>

A sample of 100 mm×200 mm (N=10) was obtained from each nonwoven fabric, the basis weight of the sample was obtained, and the average value of the obtained basis weight was used as the basis weight of each nonwoven fabric.

<Measuring method of average fiber diameter>

Samples of 10 mm x 10 mm were prepared by cutting out samples from each non-woven fabric and placing them on the preforms respectively. Appropriate drops of glycerol were applied to each sample to soak the entire sample in glycerol and a coverslip was placed on the sample. Then, the sheet surface of each sample was observed at a magnification of 1000 times using a known optical microscope (for example, VHC-100 Digital Microscope Lens VH-Z450 manufactured by KEYENCE Corporation). The fiber diameter of the fibers (N=50) exposed from the sheet surface was measured, and the average value thereof was used as the average fiber diameter.

<Measuring method of surface properties>

By using KES-FB4-A-AUTO (Automatic Surface Tester) manufactured by Kato Tech Co., Ltd., each nonwoven fabric having a range of 100 mm × 100 mm was extracted as a sample, and the sample was placed on a test stand with a smooth metal flat surface Come up to measure the surface properties. In the manufacture of each nonwoven fabric, each sample was moved horizontally by 0 to 2 cm in the machine direction (direction of fiber orientation) at a constant speed of 0.1 cm/sec using a rubbing head (gauge head) with an outer dimension of 5 mm x 5 mm. Under the condition that the initial load is 50 gf, each numerical value is calculated when MIU is the average friction coefficient in the moving section and MMD is the standard deviation of the friction coefficient. Each sample was subjected to the same measurement five times, and the average value of the measurement results was used as the value of MIU and the value of MMD for each sample.

<Measurement method of thickness T0, Tm and compressive properties>

To measure the thickness of each nonwoven fabric, a compression tester KES-FB3-AUTO-A manufactured by Kato Tech Co., Ltd. was used. First, a piece of 100 mm × 100 mm in size was cut out from each non-woven fabric as a sample, the center of the sample was lightly sandwiched between discs arranged up and down, and the compressed area (area of the disc) was measured. Thickness T0 of each sample at 2.0 cm ² and a load of 0.49 hPa. Then, the measurement sample was compressed under a load of 49.03 hPa at a loading speed of 0.02 mm/sec, and the thickness Tm was measured under a load of 49.03 hPa. In addition, when WC represents the working load (N·m/m ² ) required when compressing from the thickness T0 to the thickness Tm, and WC2 represents the working load required when recovering from the thickness Tm to the thickness T0, it is obtained according to the following calculation formula Compression recovery rate RC (%).

RC(%)=WC2/WC×100

<Measurement result>

Referring to the results in Table 1, it is clear that, as in Comparative Examples 1 to 3, when the flexural rigidity of the nonwoven fabric is more than 0.0096 N·m ² /m × 10 ^-4 , it is easy to get on the wearer's skin Wrinkles are generated, and as in Examples 1 to 5, when the flexural rigidity of the nonwoven fabric is 0.0096 N·m ² /m×10 ⁻⁴ or less, it is unlikely that wrinkles will be generated on the skin of the wearer . In addition, it is clear that, as in Example 5, when the flexural rigidity is 0.0035 N·m ² /m×10 ⁻⁴ or more, the waist portion 20 is not broken in use, and the nonwoven fabric of Example 5 can Used as the skin side panel portion 221 without any problem.

In addition, the compression recovery rate RC of the nonwoven fabric according to any one of Examples 1 to 5 was 50% or less, which was lower than that of the nonwoven fabric in any one of Comparative Examples 1 to 3. Also in view of this, it is clear that a flexible nonwoven fabric with low flexural rigidity has protrusions that are easily crushed in the folds, and is less likely to generate fold marks.

In addition, the basis weight of the nonwoven fabric according to any one of Examples 1 to 5 was in the range of 10 g/m ² or more and 30 g/m ² or less, and the apparent density under a load of 49.03 hPa fell to 0.12 g /cm ³ or more and 0.2 g/cm ³ or less. Therefore, as long as the basis weight and apparent density of the nonwoven fabric are within the above-mentioned ranges, flexibility can be obtained while obtaining appropriate tensile strength.

Comparing Example 1 (nonwoven fabric consisting of polyethylene fibers with a fiber diameter of 14.83 μm) and Comparative Example 1 (nonwoven fabric consisting of polypropylene fibers with a fiber diameter of 12.19 μm), the MIU of Example 1 The coefficient of variation MMD/MIU×100 of the friction coefficient of Example 1 is 2.57%, while the coefficient of variation of the friction coefficient of Comparative Example 1 MMD/MIU×100 is 3.28%. Therefore, since the non-woven fabric is composed of relatively soft polyethylene fibers, the coefficient of friction MIU is high. As a result, the coefficient of variation MMD/MIU×100 of the coefficient of friction is low, the variation of the coefficient of friction is reduced, and the sheet surface is smooth. Therefore, when the user moves the fingertip in the plane direction with respect to the surface of the nonwoven fabric, the amount of fibers that come into contact with the fingerprint so as to adhere to the fingerprint is large, and a smooth feeling can be imparted.

Regarding the nonwoven fabric of any one of Comparative Examples 2 and 3 composed of conjugate fibers, the coefficient of variation MMD/MIU×100 of the coefficient of friction exceeded 6%. Therefore, as compared with the nonwoven fabric of any one of Examples 1 to 5 composed of single fibers of polyethylene fibers, the smoothness of the sheet surface was deteriorated. In other words, in the case where the nonwoven fabric according to any one of Examples 1 to 5 is composed of polyethylene fibers having a fiber diameter of 14 μm or more and 22 μm or less, the coefficient of variation MMD of the friction coefficient based on the KES method is easily obtained Soft nonwoven fabric having a smooth sheet surface in which /MIU×100 is 2% or more and 6% or less. The measured results of the friction coefficient MIU according to Examples 1, 2, 4 and 5 were 0.268 to 0.335, so the friction coefficient MIU is preferably at least 0.25 (above).

The embodiments of the present invention have been described above, however, the above-described embodiments are for easier understanding of the present invention and are not intended to explain the present invention in a limited manner. In addition, the present invention may be modified or improved without departing from the spirit of the present invention, and equivalents of the modified or improved configurations are included.

Description of reference numerals

1 Shorts-type disposable diapers (absorbent articles)

10 Absorbent body

11 Absorbent body, 11A Absorbent core, 11B Core wrap sheet

12 top sheet, 13 back sheet, 14 exterior sheet

15 Leg elastics

20 Abdominal waist part (waist part)

20A Waist Side, 20B Absorbent Body Side

20C Middle, 20D Core Side

21 The first sheet (inner sheet, second inner sheet, third inner sheet)

22 Second piece, 221 Skin side piece, 222 Non-skin side piece

23 Elastic thread (stretchable member), 23a to 23e Waist side elastic thread

23f core side elastic, 23g middle elastic

24 inner sheet, 25 inner sheet, 26 protrusion

30 Back waist part (waist part), 31 1st piece

32 second piece, 33 elastic thread

Waist part of 40 comparative examples

50 Adhesive

240 stretch sheet (stretch sheet part, inner sheet part), 250 protruding part

400 Skin side panels of the comparative example

Claims (30)

1. An absorbent article having a longitudinal direction and a transverse direction, The absorbent article includes: an absorbent body that includes an absorbent core; and a pair of waist portions, each waist portion including a skin side panel portion and a plurality of elastic threads, the skin side panel is arranged at the position closest to the skin side, the plurality of elastic threads are capable of expanding and contracting in the lateral direction, In at least one of the pair of waist portions, The flexural rigidity of the skin side panel part by KES method is 0.0096N·m ² /m×10 ^-4 or less, The waist portion has an inner layer sheet portion, The inner layer sheet portion is located on the waist side in the longitudinal direction with respect to the absorptive main body, The inner layer sheet portion is located between the skin side sheet portion and the elastic thread in the thickness direction of the waist portion, The flexural rigidity by the KES method of the inner-layer sheet portion is higher than the flexural rigidity of the skin-side sheet portion. 2. The absorbent article according to claim 1, wherein The waist portion includes a non-skin side panel portion disposed at the most non-skin side position, The elastic thread is arranged between the inner layer sheet portion and the non-skin side sheet portion in the thickness direction, and The said skin side sheet part is a part which folded the waist side edge part in the said longitudinal direction of the said non-skin side sheet part toward the skin side. 3. The absorbent article of claim 2, wherein The waist-side end portion in the longitudinal direction of the inner layer sheet portion is folded toward the skin side. 4. The absorbent article of claim 1, wherein The waist portion includes a second inner layer panel portion and a non-skin side panel portion, the second inner layer sheet portion is arranged on the non-skin side with respect to the inner layer sheet portion, the non-skin side panel portion is arranged at the most non-skin side position, The flexural rigidity of the second inner layer sheet portion based on the KES method is 0.0096 N·m ² /m × 10 ^-4 or less, The elastic thread is arranged between the second inner layer sheet portion and the non-skin side sheet portion in the thickness direction, and The skin-side sheet portion is a portion formed by folding the waist-side end portion in the longitudinal direction of the non-skin-side sheet portion toward the skin side. 5. The absorbent article of claim 1, wherein The waist portion includes a third inner layer panel portion and a non-skin side panel portion, the third inner layer sheet portion is arranged on the non-skin side with respect to the inner layer sheet portion, the non-skin side panel portion is arranged at the most non-skin side position, The waist portion has a waist side portion and a core side portion, The waist side portion is a portion located on the waist side in the longitudinal direction with respect to the absorptive main body, The said core side part is a part which overlaps with the said absorptive core in the said thickness direction, the plurality of elastic threads include a waist-side elastic thread arranged on the waist side portion and a core-side elastic thread arranged on the core side portion, The waist-side elastic thread is arranged between the inner layer sheet portion and the third inner layer sheet portion in the thickness direction, and The core-side elastic thread is arranged between the third inner layer sheet portion and the non-skin side sheet portion in the thickness direction. 6. The absorbent article of claim 5, wherein the waist portion has an intermediate portion between the waist side portion and the core side portion in the longitudinal direction, the plurality of elastic strands include an intermediate elastic strand disposed at the intermediate portion, and some of the intermediate elastic wires are arranged at positions between the inner layer sheet portion and the third inner layer sheet portion in the thickness direction, and Some of the intermediate elastic strands are arranged at positions between the third inner sheet portion and the non-skin side sheet portion in the thickness direction. 7. The absorbent article according to any one of claims 1 to 6, wherein The waist portion has a waist side portion and an absorbent main body side portion, The waist side portion is a portion located on the waist side in the longitudinal direction with respect to the absorptive main body, The absorptive main body side portion is a portion overlapping the absorptive main body in the thickness direction, and A value obtained by dividing the magnitude of the force for extending the side part of the waist by a unit length in the lateral direction by the length of the side part of the waist part in the longitudinal direction less than A value obtained by dividing the magnitude of the force by which the side part of the absorptive main body is extended by a unit length in the transverse direction by the length of the side part of the absorptive main body in the longitudinal direction. 8. The absorbent article according to any one of claims 1 to 7, wherein The waist side end of the inner layer sheet portion is located on the waist side in the longitudinal direction with respect to the elastic thread arranged at the most waist side position among the plurality of elastic threads. 9. The absorbent article according to any one of claims 1 to 8, wherein The crotch side end of the inner layer sheet part is located on the crotch side in the longitudinal direction with respect to the waist side end of the absorptive main body. 10. The absorbent article according to any one of claims 1 to 9, wherein The flexural rigidity by the KES method of the skin side sheet portion is 0.0035 N·m ² /m×10 ⁻⁴ or more. 11. The absorbent article according to any one of claims 1 to 10, wherein The compression recovery rate RC by the KES method of the skin side panel is 15% or more and 50% or less. 12. The absorbent article of any one of claims 1 to 11, wherein The skin side sheet portion has a basis weight of 10 g/m ² or more and 30 g/m ² or less, and The skin side sheet portion has an apparent density of 0.12 g/cm ³ or more and 0.2 g/cm ³ or less under a load of 49.03 hPa. 13. The absorbent article of any one of claims 1 to 12, wherein The skin side sheet portion includes fibers having a fiber diameter of 14 μm or more and 22 μm or less, and The coefficient of variation MMD/MIU×100 of the friction coefficient by the KES method of the skin side sheet portion is 2% or more and 6% or less. 14. The absorbent article of any one of claims 1 to 13, wherein The coefficient of friction MIU of the skin side panel portion is at least 0.25. 15. The absorbent article of any one of claims 1 to 14, wherein The skin side panel portion contains polyethylene fibers. 16. An absorbent article having a machine direction and a transverse direction, The absorbent article includes: an absorbent body that includes an absorbent core; and a pair of waist parts, each waist part including a skin side panel part arranged at a position closest to the skin side, In at least one of the pair of waist portions, The flexural rigidity of the skin side panel part by KES method is 0.0096N·m ² /m×10 ^-4 or less, an inner layer sheet portion is arranged on the non-skin side with respect to the skin side sheet portion, The flexural rigidity of the inner-layer sheet portion based on the KES method is higher than the flexural rigidity of the skin-side sheet portion, The inner layer sheet portion is arranged on the skin side of the absorptive main body, and spans the waist side edge of the absorptive main body in the longitudinal direction. 17. The absorbent article of claim 16, wherein The waist portion includes a non-skin side panel portion disposed at the most non-skin side position, The skin side sheet portion is a portion formed by folding the waist side end portion in the longitudinal direction of the non-skin side sheet portion toward the skin side, The inner sheet portion has a skin side portion and a non-skin side portion, The skin side portion is a portion formed by folding the waist side end portion in the longitudinal direction toward the skin side, the non-skin side portion is a portion arranged on the non-skin side with respect to the skin side portion, A stretchable member is arranged between the non-skin side portion of the inner layer sheet portion and the non-skin side sheet portion in the thickness direction of the waist portion, the telescopic member is expandable and retractable in the lateral direction, and The skin side part of the inner layer sheet part is arranged on the skin side of the absorptive main body, spanning the waist side edge of the absorptive main body in the longitudinal direction. 18. The absorbent article of claim 17, wherein The crotch side edge of the skin side part of the said inner-layer sheet part is located in the crotch side in the longitudinal direction with respect to the waist side edge of the said absorptive core. 19. The absorbent article of claim 17 or 18, wherein In the thickness direction of the waist portion, a stretchable sheet portion is arranged between the skin side portion and the non-skin side portion of the inner layer sheet portion, The stretchable sheet portion can expand and contract in the lateral direction, The elastic sheet portion has a higher flexural rigidity based on the KES method than the skin-side sheet portion, and The said elastic sheet part is arrange|positioned on the skin side of the said absorptive main body, spanning the waist side edge of the said longitudinal direction of the said absorptive main body. 20. The absorbent article of claim 19, wherein The crotch side edge of the skin side part of the inner layer sheet part, the crotch side edge of the skin side part and the crotch side edge of the elastic sheet part are displaced from each other in the longitudinal direction. 21. The absorbent article of claim 20, wherein The crotch side edge of the skin side part of the said inner-layer sheet part is located in the most crotch side position in the said longitudinal direction. 22. The absorbent article of claim 16, wherein The said inner layer sheet part is a stretchable sheet part which can expand and contract in the said horizontal direction. 23. The absorbent article of any one of claims 19 to 22, wherein The crotch side edge of the elastic sheet part is located on the waist side in the longitudinal direction with respect to the waist side edge of the absorptive core. 24. The absorbent article of any one of claims 16 to 23, wherein The skin side sheet portion is arranged on the skin side of the absorptive main body and spans the waist side edge of the absorptive main body in the longitudinal direction. 25. The absorbent article of any one of claims 16 to 24, wherein The flexural rigidity by the KES method of the skin side sheet portion is 0.0035 N·m ² /m×10 ⁻⁴ or more. 26. The absorbent article of any one of claims 16 to 25, wherein The compression recovery rate RC by the KES method of the skin side panel is 15% or more and 50% or less. 27. The absorbent article of any one of claims 16 to 26, wherein The skin side sheet portion has a basis weight of 10 g/m ² or more and 30 g/m ² or less, and The skin side sheet portion has an apparent density of 0.12 g/cm ³ or more and 0.2 g/cm ³ or less under a load of 49.03 hPa. 28. The absorbent article of any one of claims 16 to 27, wherein the skin side sheet portion includes fibers having a fiber diameter of 14 μm or more and 22 μm or less, and The coefficient of variation MMD/MIU×100 of the friction coefficient by the KES method of the skin side sheet portion is 2% or more and 6% or less. 29. The absorbent article of any one of claims 16 to 28, wherein The coefficient of friction MIU of the skin side panel portion is at least 0.25. 30. The absorbent article of any one of claims 16 to 29, wherein The skin side panel portion contains polyethylene fibers.

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