AU2015254266A1

AU2015254266A1 - Disposable diaper

Info

Publication number: AU2015254266A1
Application number: AU2015254266A
Authority: AU
Inventors: Toshimitsu Baba; Shunsuke Masaki; Kaori MINAMI
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 2014-05-02
Filing date: 2015-04-21
Publication date: 2016-11-17
Also published as: JP6468724B2; BR112016024559B1; CN106232077B; BR112016024559A2; PH12016502110A1; CN106232077A; PH12016502110B1; KR20160147796A; WO2015166844A1; JP2015211782A

Abstract

This disposable diaper (1) is provided with a composite elastic member (5) in a waistband portion (WP). The composite elastic member comprises a first non-woven fabric sheet portion (6U) and a second non-woven fabric sheet portion (6L) that are superimposed over each other and a plurality of elastic members (7) that extend along the waistband direction (DW) between the non-woven fabric sheet portions. The first and second non-woven fabric sheet portions each have a plurality of concave-convex areas (41) and at least one non-concave-convex area (43) that separates the concave-convex areas from each other in a direction that is orthogonal to the waistband direction. The waistband portion includes a waistband opening side area (AWO) that is located on the waistband opening side and a leg opening side area (ALO) that is located more toward the leg opening (LO) sides than the waistband opening side area. The spacing between elastic members (LL) disposed in the leg opening side area is larger than the spacing between elastic members (LW) disposed in the waistband opening side area.

Description

AC893-PCT - 1 -

DESCRIPTION

Title of Invention DISPOSABLE DIAPER Technical Field [0001]

The present invention relates to a disposable diaper .

Background Art [0002] A pants-type wearable article has been disclosed having a stiffening sheet made of a nonwoven fabric, woven fabric, plastic film, foamed plastic sheet or paper disposed on the section near the waistband opening of the waistband portion that elastically contracts to form a gather (see PTL 1). This partially forms low-stiffness regions and high-stiffness regions in the waistband direction at the sections near the waistband opening of the pants-type wearable article. As a result, the sections near the waistband opening at the waistband portion softly contact the skin of the wearer by the presence of the gather, while the stiffness is increased at the sections where the stiffening sheet has been situated, making it easier to grip those sections, and thus facilitating lifting of the pants-type wearable article .

Citation List Patent literature [0003] PTL 1: Japanese Unexamined Patent Publication No. 2004-329505 Summary of Invention Technical Problem [0004]

However, in order to obtain the effect of the invention disclosed in PTL 1, it is necessary to selectively grip the high-stiffness regions when donning 2 the disposable diaper (pants-type wearable article), as the effect may not be obtained when the low-stiffness regions are gripped. Furthermore, when the entire perimeter region of the waistband opening is a highstiffness region, the feel on the skin may become hard, potentially impairing the feel during wear.

[0005]

Moreover, with the invention disclosed in PTL 1 it is necessary to place a stiffening sheet as an additional member in the disposable diaper. This can potentially result in increased production cost.

[0006]

It is therefore an object of the present invention to provide a disposable diaper that is easy to lift up when worn, without requiring placement of an additional member.

Solution to Problem [0007]

In order to achieve the object stated above, the invention provides: a disposable diaper in which a waistband opening and a pair of leg openings are formed and which has an absorbing element having a liquid-permeable top sheet, a liquid-impermeable back sheet and a liquid-absorbing absorbent body lying between the top sheet and the back sheet, the disposable diaper comprising a waistband portion, provided between the waistband opening and the leg openings of the disposable diaper, that covers the waist of the wearer, and a crotch section, forming the leg openings together with the waistband portion, that covers the crotch of the wearer, a composite elastic member being formed in the waistband portion, the composite elastic member comprising a first nonwoven fabric sheet section and a second nonwoven fabric sheet section which are mutually overlaid, and a 3 plurality of elastic members extending in the waistband direction between the first nonwoven fabric sheet section and the second nonwoven fabric sheet section, the first nonwoven fabric sheet section and the second nonwoven fabric sheet section each comprising: a plurality of concavoconvex regions at least partially comprising protrusions and recesses that alternately repeat along the waistband direction and extend in the direction orthogonal to the waistband direction, and at least one non-concavoconvex region that separates the concavoconvex regions from each other in the direction orthogonal to the waistband direction, and the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are overlaid in such a manner that the concavoconvex regions of the first nonwoven fabric sheet section and the concavoconvex regions of the second nonwoven fabric sheet section are mutually aligned and the non-concavoconvex region(s) of the first nonwoven fabric sheet section and the non-concavoconvex region (s) of the second nonwoven fabric sheet section are mutually aligned, the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are joined together through the elastic member, the waistband portion includes a waistband opening side area located on the waistband opening side and leg opening side areas located further to the leg opening sides than the waistband opening side area, and the spacing between the elastic members situated in the leg opening side areas is larger than the spacing between the elastic members situated in the waistband opening side area.

Advantageous Effects of Invention [0008]

In the disposable diaper of the invention, a composite elastic member having a larger spacing between elastic members situated in the leg opening side areas 4 than the spacing between the elastic members situated in the waistband opening side area, is provided in the waistband portion of the disposable diaper. As a result, according to the invention it is possible to provide a disposable diaper that is easy to grip at the waistband portion, and thus easy to lift up, when it is worn, without requiring placement of an additional member. Furthermore, since the disposable diaper of the invention does not require placement of an additional member, it is possible to avoid increased production cost.

Brief Description of Drawings [0009]

Fig. 1 is a schematic perspective view of a disposable diaper according to an embodiment of the invention .

Fig. 2A is a plan view schematically showing the spread-out state of the disposable diaper of Fig. 1.

Shown is the skin side when worn.

Fig. 2B is a simplified magnified cross-sectional view long line IIB-IIB of Fig. 2A.

Fig. 2C is a simplified cross-sectional view long line IIC-IIC of Fig. 2A.

Fig. 3 is a bottom view schematically showing the spread-out state of the disposable diaper of Fig. 1.

Shown is the outer side when worn.

Fig. 4(A) is a partial magnified view of the stomach side portion of the waistband portion of the disposable diaper of Fig. 3, and (B) is a cross-sectional view of the partial magnified view.

Fig. 5A is a magnified perspective view of the cut portion of section VA of Fig. 4.

Fig. 5B is an exploded perspective view of Fig. 5A.

Fig. 5C is a magnified view of the periphery of the cross-section of the elastic member of Fig. 5A.

Fig. 6 is a schematic diagram of an apparatus for production of a composite elastic member.

Fig. 7 is a perspective view of a cut-tooth gear 5 roll and continuous gear roll in a shaping apparatus in the apparatus for production of a composite elastic member.

Fig. 8 is a front view of the cut-tooth gear roll and continuous gear roll of Fig. 7.

Fig. 9 is a partial side view of the cut-tooth gear roll and continuous gear roll of Fig. 7.

Fig. 10A is a magnified cross-sectional view schematically showing the meshing section between a cut-tooth gear roll and a continuous gear roll, and a nonwoven fabric sheet deformed between them, at a cut-tooth portion of the cut-tooth gear roll, the view being linearly expanded in the peripheral direction of the cut-tooth gear roll and continuous gear roll.

Fig. 10B is a magnified cross-sectional view schematically showing the meshing section between a cut-tooth gear roll and a continuous gear roll, and a nonwoven fabric sheet deformed between them, at a discontinuous tooth portion of the cut-tooth gear roll, the view being linearly expanded in the peripheral direction of the cut-tooth gear roll and continuous gear roll.

Fig. 11 is a plan view (A) and cross-sectional view (B) of the assembly before folding of one nonwoven fabric sheet section with the folding apparatus.

Fig. 12 is a plan view (A) and cross-sectional view (B) of the assembly after folding of one nonwoven fabric sheet section with the folding apparatus.

Fig. 13A is a diagram showing an example of the form before the composite elastic member of this embodiment has been compressed in the second direction.

Fig. 13B is a diagram showing an example of the form after the composite elastic member of this embodiment has been compressed in the second direction.

Fig. 14A is a diagram showing an example of the form before the composite elastic member formed from two non-shaped nonwoven fabric sheet sections has been compressed 6 in the second direction.

Fig. 14B is a diagram showing an example of the form after the composite elastic member formed from two non-shaped nonwoven fabric sheet sections has been compressed in the second direction.

Fig. 15A is a diagram illustrating the size of the test strip in the compressive strength test.

Fig. 15B is a perspective view showing an overview of the test strip in the compressive strength test.

Fig. 16 is a graph showing an example of changes in time and compressive force in a compressive strength test.

Description of Embodiments [0010]

The present invention will now be described in greater detail with reference to the accompanying drawings. It is to be understood that the drawings may not be drawn to the same size, scale or form for the actual constituent elements, in order to aid in understanding of the invention and to simplify the explanation of the drawings.

[0011] A disposable diaper 1 according to an embodiment of the invention will now be described with reference to Figs. 1 to 5C. The disposable diaper 1 of this embodiment is an underwear-type disposable diaper. It is to be understood that in the drawings, some or all of the wrinkles formed in the disposable diaper 1 may not be shown in the drawings, for easier visualization of the drawings. The disposable diaper 1 shown in Fig. 2A and Fig. 3 is shown in a state spread out in a flat manner with the side portion IS of the disposable diaper 1 cut from the waistband opening WO to the leg opening LO, so that the wrinkles are stretched without creating excessive tension on the members composing the disposable diaper 1. In these spread-out views, the term "waistband direction DW" is used as the definition of the direction, 7 and the waistband direction DW in these spread-out views is essentially orthogonal to the direction in which the crotch section CP extends. Also, the "direction orthogonal to the waistband direction DW" is the direction in which the composite elastic member 5 extends, of the direction orthogonal to the waistband direction DW described above. Also, it is to be understood that the sheet-like members may be represented by a single line in the schematic cross-sectional views of Fig. 2B and Fig. 2C.

[0012]

The disposable diaper 1 of this embodiment comprises a waistband portion WP that covers the waist of the wearer over the entire waistband direction DW when worn, and a crotch portion CP that covers the crotch of the wearer.

[0013]

As shown in Fig. 1, the waistband portion WP includes a waistband portion edge WPE forming a waistband opening WO, located above the disposable diaper 1 when worn. The waistband portion WP includes a stomach side portion WPS located on the abdominal side of the wearer when worn, and a back side portion WPB located on the back side of the wearer when worn. The stomach side portion WPS and back side portion WPB are joined by heat sealing, for example, at each side portion IS of the disposable diaper 1. As shown in Fig. 2A, in the disposable diaper 1 of this embodiment, the waistband portion edge WPE includes a stomach waistband portion edge WPES located on the stomach side of the wearer during use of the disposable diaper 1, and a back waistband portion edge WPEB located on the back side of the wearer during use of the disposable diaper 1. A composite elastic member 5, described in detail below, is provided in the waistband portion WP.

[0014]

The crotch portion CP extends in the direction - 8 - orthogonal to the waistband direction DW, from the stomach side portion WPS to the back side portion WPB of the waistband portion WP. The crotch portion CP has a smaller dimension in the waistband direction DW than in the waistband portion WP, whereby leg openings LO are formed in the disposable diaper 1. With this construction, as shown in Fig. 1, the waistband portion WP is located between the waistband opening WO and the leg openings LO, and the crotch portion CP forms the waistband portion WP and the leg openings LO.

[0015]

In the disposable diaper 1 of this embodiment, an outer sheet 2 is provided on the outer surface of the crotch portion CP, and an absorbing element 3 is further provided, being disposed on the outer sheet 2. The absorbing element 3 is provided from the stomach side portion WPS of the waistband portion WP through the crotch portion CP through to the back side portion WPB of the waistband portion WP, running along the lengthwise direction of the crotch portion CP.

[0016]

According to this embodiment, the outer sheet 2 is composed of different known nonwoven fabrics that are hydrophobic or liquid-impermeable, and for example, it may be formed from a spunbond nonwoven fabric, point bond nonwoven fabric, SMS (spunbond/meltblown/spunbond) nonwoven fabric, liquid-impermeable plastic film, or a laminate thereof, having a basis weight in the range of about 10 to 40 g/m2.

[0017]

Also, the absorbing element 3 is disposed so that the distance LEB in the direction orthogonal to the waistband direction DW between the back waistband portion edge WPEB of the waistband portion WP and the lengthwise edge 3EB of the absorbing element located on the back waistband portion edge WPEB side, is longer than the distance LES in the direction orthogonal to the waistband 9 direction DW between the stomach waistband portion edge WPES and the lengthwise edge 3ES of the absorbing element located on the stomach waistband portion edge WPES side of the waistband portion WP. When these distances LEB and LES are not constant across the waistband direction DW, the comparison may be made based on the minimum distances .

[0018]

As shown in Fig. 2B, the absorbing element 3 has a liquid-impermeable back sheet 3B located on the back surface on the side opposite the liquid-permeable top sheet 3T which is located on the front surface of the wearer side when worn, and a liquid-absorbing absorbent body 3C lying between the top sheet 3T and the back sheet 3B. In addition, the absorbent body 3C comprises a liquid-absorbing core wrapped with a core wrap sheet (not shown). The core wrap sheet is a sheet that covers the liquid-absorbing core in order to improve the shape retention and fluid diffusibility of the liquid-absorbing core. The top sheet 3T and core wrap sheet may be separate, or the top sheet 3T and the core wrap sheet may be formed as a single sheet.

[0019]

For the top sheet 3T of the absorbing element 3 there may be used any of various fiber nonwoven fabrics that are liquid-permeable, and for example, an air-through fiber nonwoven fabric, spunbond nonwoven fabric, SMS nonwoven fabric or the like having a basis weight of about 15 to 45 g/m2.

[0020]

The back sheet 3B of the absorbing element 3 is liquid-impermeable, and it may be formed from a leak-resistant (liquid-impermeable) plastic film or poorly liquid-permeable fiber nonwoven fabric, or a laminate thereof, and for example, it may be made of primarily a plastic film, or a laminate of a nonwoven fabric and a plastic film. 10 [0021]

The absorbent core of the liquid-absorbing absorbent body 3C in the absorbing element 3 is obtained by mixing super-absorbent polymer particles (SAP) and fluff pulp or thermoplastic synthetic fibers (staple fibers), and forming the mixture into a prescribed shape. Alternatively, there may be used various known absorbent cores, for example, having polymer particles dispersed in thermoplastic rigid fibers, or polymer particles dispersed on a core wrap sheet and anchored with an adhesive .

[0022]

The core wrap sheet of the absorbent body 3C used may be any of various types of fiber nonwoven fabrics or tissue sheets having liquid permeability on at least a portion of the skin side, and for example, there may be used an air-through fiber nonwoven fabric, spunbond nonwoven fabric, SMS nonwoven fabric, or tissue sheet absorbent body with a basis weight of 8 to 30 g/m2.

[0023]

The disposable diaper 1 comprises a pair of antileakage walls 4 each extending along the lengthwise direction of the crotch portion CP, on both sides of the absorbing element 3 separated by the center line C. The anti-leakage walls 4 are members that prevent leakage of discharged body fluids such as urine from the disposable diaper 1.

[0024]

The anti-leakage walls 4 each have a stationary end 4S where the anti-leakage wall 4 is anchored to the side edge section of the absorbing element 3, and a non-anchored free end 4F located at the edge on the side opposite the stationary end 4S. The anti-leakage walls 4 also each have a free end portion 4FP including the free end 4F. The anti-leakage walls 4 of this embodiment are each formed from a nonwoven fabric sheet and an elastic member 4E attached to the free end portion 4FP along the - 11 -free end 4F.

[0025]

The composite elastic member 5 provided on the waistband portion WP of the disposable diaper 1 comprises two nonwoven fabric sheet portions 6U, 6L which are mutually overlaid, and a plurality of filamentous elastic members 7 extending in the waistband direction DW between the inner side nonwoven fabric sheet portion 6U and the outer side nonwoven fabric sheet portion 6L. The inner side nonwoven fabric sheet portion 6U and outer side nonwoven fabric sheet portion 6L are joined together via the elastic members 7. The two nonwoven fabric sheet portions 6U, 6L are each composed of an outer side nonwoven fabric sheet portion 6L located on the outer side when worn, and an inner side nonwoven fabric sheet portion 6U located on the wearer side when worn, which is the opposite side. As shown in Fig. 2C, some of the elastic members 7 among the plurality of elastic members 7 are provided at locations overlapping with the location where the absorbing element 3 is present.

[0026]

For this embodiment, an SMS nonwoven fabric with a basis weight of 15 g/m2 is used for the nonwoven fabric sheet 6. However, the invention is in no way limited to this. As the nonwoven fabric sheet 6 there may be used a spunbond nonwoven fabric, meltblown nonwoven fabric, heat rolled nonwoven fabric, an SMS nonwoven fabric as a combination of a spunbond nonwoven fabric and a meltblown nonwoven fabric, an air-through nonwoven fabric, a spunlace nonwoven fabric, an airlaid nonwoven fabric, or the like. Also, the material of the nonwoven fabric sheet 6 may be polyethylene, polypropylene, polyester, acryl or the like.

[0027]

However, it is preferred to use for the nonwoven fabric sheet 6 a long filament nonwoven fabric formed by direct spinning without cutting the filaments, such as an 12 SMS nonwoven fabric or spunbond nonwoven fabric. This is from the viewpoint of minimizing reduction in strength of the nonwoven fabric sheet necessary for shaping treatment, and because the ductility is high, while the nonwoven fabric sheet itself 6 will be thinner than using a staple fiber nonwoven fabric, and it will be possible to produce a fabric with high planarity (flatness).

[0028]

For this embodiment, LycraR having 470 dtex is used for the elastic member 7. However, the invention is in no way limited to this. Elastic yarn such as urethane spandex may be used for the elastic members 7. There are used several elastic yarn filaments of about 30 to 1500 dtex as the size, and preferably elastic yarn with the same size or with different sizes. If the size is 30 dtex or smaller, the number of elastic yarn filaments used per unit width will increase, tending to require larger production equipment, and if it is 1500 dtex or greater, the spacing between adjacent elastic yarn filaments will increase, potentially resulting in non-uniform meshing between the nonwoven fabric sheet portions 6U, 6L. The material used for the elastic members 7 may also be synthetic rubber such as styrene-butadiene, butadiene, isoprene or neoprene, natural rubber, EVA, SIS, SEBS, SEPS, expandable and shrinkable polyolefin, polyurethane, or the like. The same material as used for the elastic members 7 in the composite elastic member 5 may also be used for the elastic members 4E in the anti-leakage walls 4.

[0029]

For this embodiment, the inner side nonwoven fabric sheet portion 6U and outer side nonwoven fabric sheet portion 6L are each formed from a single nonwoven fabric sheet 6 folded at both ends in the direction orthogonal to the waistband direction DW. Furthermore, as shown in Fig. 2C, the waistband portion edge WPE of the waistband portion WP forming the waistband opening WO is formed by 13 the folded portion of the single nonwoven fabric sheet 6, and the portion 6F folded to the skin side of the wearer from the waistband portion edge WPE does not overlap with the absorbing element 3.

[0030]

The stomach side portion WPS of the waistband portion WP is shown in Fig. 2C, but for this embodiment, the waistband portion edge WPE is formed of the folded portion of the single nonwoven fabric sheet, similar to the back side portion WPB of the waistband portion WP. However, the portion folded from the waistband portion edge WPE to the skin side of the wearer does not overlap with the absorbing element 3. Here, "does not overlap" means that when the disposable diaper 1 is expanded and as viewed flat, the constituent elements of the flat disposable diaper 1 do not overlap each other.

[0031]

Also, the waistband portion WP of this embodiment has three nonwoven fabric sheets 6 overlaid at the edge 6FE of the portion folded from the waistband portion edge WPE to the skin side of the wearer. As a result, the thickness is increased at the portion where the three nonwoven fabric sheets 6 are overlaid, thereby increasing the grip feel when the waistband portion WP is gripped, and further facilitating gripping of the waistband portion WP.

[0032]

As shown in Figs. 5A and 5B, the inner side nonwoven fabric sheet portion 6U and the outer side nonwoven fabric sheet portion 6L each comprise a plurality of concavoconvex regions 41 comprising protrusions 53 and recesses 51 that alternately repeat along the waistband portion WP while extending in the direction orthogonal to the waistband direction DW, and non-concavoconvex regions 43 mutually separating the concavoconvex regions 41 in the direction orthogonal to the waistband direction DW. For this embodiment, the concavoconvex regions 41 include 14 waistband opening side concavoconvex regions 41W located in the waistband opening side area AWO, and leg opening side concavoconvex regions 41L located in the leg opening side areas ALO, having larger dimensions in the direction orthogonal to the waistband direction DW than the waistband opening side concavoconvex regions 41W.

[0033]

Also, as shown in Fig. 5A, the inner side nonwoven fabric sheet portion 6U and outer side nonwoven fabric sheet portion 6L are overlaid in such a manner that the concavoconvex regions 41 of the inner side nonwoven fabric sheet portion 6U and the concavoconvex regions 41 of the outer side nonwoven fabric sheet portion 6L are mutually overlaid and in rows, and the non-concavoconvex regions 43 of the inner side nonwoven fabric sheet portion 6U and the non-concavoconvex regions 43 of the outer side nonwoven fabric sheet portion 6L are mutually overlaid and in rows. Here, "(concavoconvex regions 41 (non-concavoconvex regions 43) are mutually) in rows)" means that the concavoconvex regions 41 of the inner side nonwoven fabric sheet portion 6U and the concavoconvex regions 41 of the outer side nonwoven fabric sheet portion 6L (the non-concavoconvex regions 43 of the inner side nonwoven fabric sheet portion 6U and the non-concavoconvex regions 43 of the outer side nonwoven fabric sheet portion 6L) extend parallel to each other.

[0034]

Also, as shown in Fig. 5C, the two nonwoven fabric sheet portions 6U, 6L are joined together at bonding sections 45 by an adhesive via the elastic members 7 in the non-concavoconvex regions 43U, 43L. For this embodiment, the bonding sections 45 are dispersed so as to cover the entire peripheries of the elastic members 7.

[0035]

For this embodiment, in the concavoconvex regions 41, the protrusions 53L of the outer side nonwoven fabric sheet portion 6L enter into the recesses 51U of the inner 15 side nonwoven fabric sheet portion 6U, and the protrusions 53U of the inner side nonwoven fabric sheet portion 6U enter into the recesses 51L of the outer side nonwoven fabric sheet portion 6L. Thus, the concavoconvex regions 41 of the inner side nonwoven fabric sheet portion 6U and the outer side nonwoven fabric sheet portion 6L are mutually adjacent in the thickness direction DT of the composite elastic member 5. In contrast, the non-concavoconvex regions 43L, 43U formed in the inner side nonwoven fabric sheet portion 6U and the outer side nonwoven fabric sheet portion 6L are mutually separate in the thickness direction DT of the composite elastic member 5.

[0036]

Incidentally, as shown in Fig. 4, the waistband portion WP includes a waistband opening side area AWO located on the waistband opening WO side, in which the plurality of elastic members 7 in the composite elastic member 5 are disposed at an essentially constant spacing LW, and leg opening side areas ALO located more toward the leg opening LO sides than the waistband opening side area AWO, in which the plurality of elastic members 7 in the composite elastic member 5 are disposed at an essentially constant different spacing LL. For this embodiment, the spacing LL between elastic members 7 situated in the leg opening side areas ALO is larger than the spacing LW between elastic members 7 situated in the waistband opening side areas AWO. Here, the spacing between the elastic members 7 is the distance between the centers of the elastic members 7 in the direction orthogonal to the waistband direction DW.

[0037]

Throughout the present specification, one portion of the waistband portion WP including elastic members 7 situated at both constant spacings is considered to be a single region. In addition, a plurality of regions are present in the waistband portion WP having mutually 16 different spacings between the elastic members 7, and a disposable diaper 1 including a construction in which, of two regions among these regions, the spacings between the elastic members 7 in the region located on the leg opening LO side are wider than the spacings between the elastic members 7 in the region located on the waistband opening WO, is also encompassed within the scope of the invention .

[0038]

The description above concerns mainly the stomach side portion WPS of the waistband portion, as it pertains to the waistband portion WP. However, in the disposable diaper 1 of this embodiment, though not shown here, the back side portion WPB of the waistband portion has a similar construction to the stomach side portion WPS of the waistband portion.

[0039]

In the disposable diaper 1 of this embodiment, the waistband portion WP is provided with the composite elastic member 5 and the crotch portion CP is provided with an outer sheet 2 which is a separate member from the expandable and shrinkable material 5, but a portion of the composite elastic member 5 disposed on the waistband portion WP is shaped so as to form a leg opening LO, and may be extended so as to overlap the crotch portion CP.

[0040]

An example of a method for producing the composite elastic member 5 to form the waistband portion WP for this embodiment will now be described with reference to Figs. 6 to 12.

[0041]

Fig. 6 is a schematic diagram of an apparatus 10 for production of a composite elastic member 5. First, as an overview of the example for this method, in the apparatus 10, the concavoconvex regions 41 and non-concavoconvex regions 43 are formed in the nonwoven fabric sheet 6 by a shaping apparatus 15, and the elastic members 7 on which 17 an adhesive has been applied in an adhesive applicator 19 are attached to the nonwoven fabric sheet 6 on which the concavoconvex regions 41 and non-concavoconvex regions 43 have been shaped. Next, the assembly comprising the nonwoven fabric sheet 6 and elastic members 7 are folded by a folding apparatus 23, and finally pressure is applied onto the assembly in the thickness direction by an attachment press 25 to produce a composite elastic member 5.

[0042]

Referring to Fig. 6, first the nonwoven fabric sheet 6 composing the composite elastic member 5 is kept wound on a sheet feeder 11, and it is wound off it in the material machine direction MD and conveyed to a preheating roll 13. The preheating roll 13 preheats the wound out nonwoven fabric sheet 6A to render it more deformable, and for this example it is set to 50 to 130°C. The preheating temperature is determined according to the type and material of the nonwoven fabric sheet.

According to a different production method, the apparatus 10 does not include a preheating roll 13, and conveying is directly to the shaping apparatus 15.

[0043]

The preheated nonwoven fabric sheet 6B is then conveyed to the shaping apparatus 15. The shaping apparatus 15 is composed of a cut-tooth gear roll 15A and a continuous gear roll 15B, and for this example, the temperature is set to 50 to 130°C to facilitate shaping as with the preheating roll 13.

[0044]

Fig. 7 is a perspective view of a cut-tooth gear roll 15A and a continuous gear roll 15B in a shaping apparatus 15 in the apparatus 10 for production of a composite elastic member 5. In the drawing illustrating production of the composite elastic member 5, for the directions of the composite elastic member 5 there are used a first direction D1 which is the same direction as 18 the material machine direction MD, a second direction D2 which is the direction orthogonal to the first direction D1 on the surface of the composite elastic member 5, and the thickness direction DT of the composite elastic member 5.

[0045]

Referring to Fig. 7, the continuous gear roll 15B has a plurality of continuous teeth 27 separated in the circumferential direction, each of the continuous teeth being continuous in the widthwise direction. Also, the cut-tooth gear roll 15A has a plurality of discontinuous teeth 29 separated in the circumferential direction, each of the discontinuous teeth 29 being discontinuous in the widthwise direction by one or more cut-tooth portions 31, the cut-tooth portions 31 being aligned in the circumferential direction.

[0046]

In this production example, the discontinuous teeth 29 include narrow-width discontinuous teeth 29W with small dimensions in the widthwise direction of the cut-tooth gear roll 15A, which are to form the recesses 51 and protrusions 53 in the concavoconvex regions 41W located in the waistband opening side area AWO of the composite elastic member 5, and large-width discontinuous teeth 29L with larger dimensions in the widthwise direction of the cut-tooth gear roll 15A, which are to form the recesses 51 and protrusions 53 in the concavoconvex regions 41W located in the leg opening side areas ALO of the composite elastic member 5.

[0047]

Fig. 8 is a front view of the cut-tooth gear roll 15A and continuous gear roll 15B of Fig. 7. In this production method example, the widths Wvf of the cut-tooth portions 31f forming the non-concavoconvex regions 43 (Fig. 11), in which the folding lines FL (Fig. 11) described below are located, are larger than the widths Wvs of the other cut-tooth portions 31s. Also, the 19 widths Wgl of the large-width discontinuous teeth 29L are larger than the widths Wgw of the narrow-width discontinuous teeth 29W. In this production method example, Wvf is 2 mm, Wvs is 1 mm, Wgw is 4 mm and Wgl is 9 mm. However, the dimensions of each constituent element of the cut-tooth gear roll 15A and continuous gear roll 15B are not limited to these dimensions.

[0048]

In this production example, the narrow-width discontinuous teeth 29W and large-width discontinuous teeth 29L are each set in 6 rows in the second direction D2. However, the number of rows of discontinuous teeth 29 may be changed according to the size of the waistband portion WP and the dimensions of each location of the shaping apparatus 15.

[0049]

Fig. 9 is a partial side view of the cut-tooth gear roll 15A and continuous gear roll 15B of Fig. 7. The shapes of the cut-tooth gear roll 15A and the continuous gear roll 15B are the same as viewed from the side, and therefore their partial side views are shown in a single diagram. In this example, the protrusions TH of the teeth 27, 29 of the cut-tooth gear roll 15A and the continuous gear roll 15B are approximately 1 mm, and the spacing TP between the top sections of adjacent teeth 27, 29 is approximately 1 mm. Also, flat sections are present at the top section of each of the teeth 27, 29, the length TL in the circumferential direction of the flat section being approximately 0.1 mm. However, the dimensions of each constituent element of the cut-tooth gear roll 15A and continuous gear roll 15B are not limited to these dimensions.

[0050]

The preheated nonwoven fabric sheet 6B passes between the cut-tooth gear roll 15A and continuous gear roll 15B that are engaged and rotating in mutually opposite directions, as illustrated in Figs. 7 to 9. The 20 mechanism of shaping when the nonwoven fabric sheet 6B passes between the cut-tooth gear roll 15A and the continuous gear roll 15B, will now be explained with reference to Fig. 10A and Fig. 10B. Fig. 10A and Fig. 10B are magnified cross-sectional views schematically showing the area surrounding the meshing section between the cut-tooth gear roll 15A and continuous gear roll 15B, and a nonwoven fabric sheet 6 deformed between them, the view being linearly expanded in the peripheral direction of the cut-tooth gear roll 15A and continuous gear roll 15B. Fig. 10A is a cross-sectional view of a cut-tooth portion 31 of the cut-tooth gear roll 15A, and Fig. 10B is a cross-sectional view of a discontinuous tooth 29 portion of the cut-tooth gear roll 15A.

[0051]

As shown in Fig. 10A, the nonwoven fabric sheet 6B that is introduced into the cut-tooth portion 31 of the cut-tooth gear roll 15A is pressed by the continuous gear roll 15B toward the outer side in the radial direction of the continuous gear roll 15B, but without being deformed, thus forming non-concavoconvex regions 43. Meanwhile, as shown in Fig. 10B, the nonwoven fabric sheet 6B that has been caught between the discontinuous teeth 29 of the cut-tooth gear roll 15A and the continuous teeth 27 of the continuous gear roll 15B becomes positioned at the tooth tip portion 33B. This causes stretching between the tooth tip portion 33B, the tooth tip portion 33A and another tooth tip portion 33B, which are adjacent in a three-point bending manner, forming a protrusion 53 with the tooth tip portion 33A as the top section.

[0052]

Furthermore, stretching occurs between the tooth tip portion 33A, the tooth tip portion 33B and another tooth tip portion 33A, which are adjacent in a three-point bending manner, forming a recess 51 with the tooth tip portion 33B as the bottom section. During this time, the location in the radial direction of the gear rolls 15A, 21 15B is essentially the same for the non-concavoconvex regions 43 of the nonwoven fabric sheet 6 pressed to the continuous gear roll 15B at the cut-tooth portions 31 of the cut-tooth gear roll 15A, and the bottom sections of the recesses 51 of the nonwoven fabric sheet 6B which are positioned at the tooth tip portions 33B of the continuous gear roll 15B at the discontinuous teeth 29 portions of the cut-tooth gear roll 15A. That is, their location in the thickness direction DT of the nonwoven fabric sheet 6B are essentially the same. Thus, even after the concavoconvex regions 41 and the non-concavoconvex regions 43 have been formed in the nonwoven fabric sheet 6B, the non-concavoconvex regions 43 and the bottom sections of the recesses 51 of the nonwoven fabric sheet 6B are situated on essentially the same plane.

This plane is defined as the imaginary reference plane RP for the nonwoven fabric sheet portions 6U, 6L. The reference plane RP is flat, and the non-concavoconvex region 43 extends out on this reference plane RP. Since both of the nonwoven fabric sheet portions 6U, 6L are flexible, the reference plane RP is not necessarily flat.

[0053]

Thus, in terms of the relationship between the protrusions 53 and the reference plane RP, the protrusions 53 protrude in the thickness direction DT from the reference plane RP, i.e. from the location of the protrusion of the non-concavoconvex regions 43.

[0054]

The nonwoven fabric sheet 6C passing through the shaping apparatus 15 is then conveyed to a merging zone 21.

[0055]

Meanwhile, the elastic members 7 are kept wound on an elastic member feeder 17, and are wound out to be conveyed to the adhesive applicator 19. The elastic members 7 are subjected to a constant tension beforehand so as to be joined to the nonwoven fabric sheet 6 with 22 the prescribed elastic member attachment factor (= (length of elastic member in extended state when attached to nonwoven fabric sheet) -=- (length of elastic member in contracted state)). The following steps are carried out while maintaining the tension applied to the elastic members 7.

[0056]

The adhesive applicator 19 applies an adhesive onto the elastic members 7 A that has been conveyed from the elastic member feeder 17.

[0057]

In this production example, slit continuous coating is carried out at the adhesive applicator 19, and the elastic members 7A are matched to the sections where the adhesive has been discharged from the slit nozzles (not shown) , for application of the adhesive around the elastic members 7A. The adhesive in this case is a hot-melt adhesive, but this is not limitative.

[0058]

At the merging zone 21 where the nonwoven fabric sheet 6C and the elastic members 7B are merged, the elastic members 7B on which the adhesive has been applied are situated on the non-concavoconvex regions 43 of the nonwoven fabric sheet 6C. The assembly 5A with the elastic members 7B attached to the nonwoven fabric sheet 6C is shown in Fig. 11. As a different embodiment, the elastic members 7B on which the adhesive has been applied are disposed on the concavoconvex regions 41 of the nonwoven fabric sheet 6C.

[0059]

Next, the assembly 5A in the state shown in Fig. 11 is conveyed to the folding apparatus 23. In this production example, the folding apparatus 23 is an involuting sailor. At the involuting sailor, the assembly 5A is folded at the folding lines FL, and the upper nonwoven fabric sheet portion 6U, which is the side of the nonwoven fabric sheet 6 that overlaps, is overlaid 23 on the lower nonwoven fabric sheet portion 6L, which is the side of the nonwoven fabric sheet 6 that is overlapped, so that the non-concavoconvex regions 43 are aligned. Thus, the concavoconvex regions 41 of the nonwoven fabric sheet portions 6U, 6L are also overlaid and mutually aligned. As a result, the assembly 5A in the state shown in Fig. 11, when passed through the folding apparatus 23, becomes an assembly 5B in the state shown in Fig. 12. In another example of the production method, a shaping apparatus 15 as described above is used for separate shaping of two nonwoven fabric sheets, and the nonwoven fabric sheets are then overlaid to produce the assembly 5B.

[0060]

In this production example, the folding apparatus 23 folds the assembly 5A along the two folding lines FL. However, so long as the nonwoven fabric sheet 6 is folded so that the concavoconvex regions 41 of the upper nonwoven fabric sheet portion 6U and the concavoconvex regions 41 of the lower nonwoven fabric sheet portion 6L are overlaid and mutually aligned, and so that the non-concavoconvex regions 43 of the upper nonwoven fabric sheet portion 6U and the non-concavoconvex regions 43 of the lower nonwoven fabric sheet portion 6L are overlaid and mutually aligned, then the folding may be centered on any locations as necessary. Alternatively, it may be folded at only one location as necessary.

[0061]

The following explanation concerns the mechanism by which the protrusions 53 enter into the recesses 51 as shown in Fig. 5A when the assembly 5A is to be folded at the folding apparatus 23.

[0062]

The nonwoven fabric sheet 6 is generally soft and easily deformable, and therefore in order to transport the nonwoven fabric sheet 6 through the production steps, a constant tension is usually applied in the material 24 machine direction MD, i.e. the first direction Dl.

[0063]

In addition to this, when the assembly 5A passes through the folding apparatus 23, further tension is applied to the nonwoven fabric sheet portion 6U in the first direction Dl by the folding apparatus 23. Specifically, this tension is applied by the sailor edge (not shown) of the involuting sailor, as a concrete embodiment of the folding apparatus 23. As a result, the upper nonwoven fabric sheet portion 6U extends further in the first direction Dl than the lower nonwoven fabric sheet portion 6L. Thus, the concavoconvexity pitch in the concavoconvex regions 41 of the upper nonwoven fabric sheet portion 6U (the distance in the waistband direction DW between the recesses 51 or between the protrusions 53 that are mutually adjacent in the waistband direction DW) is slightly wider than the concavoconvexity pitch in the concavoconvex regions 41 of the lower nonwoven fabric sheet portion 6L.

[0064]

Next, when the upper nonwoven fabric sheet portion 6U is overlapped with the lower nonwoven fabric sheet portion 6L, the tension is released, returning to the state in which previously applied tension introduced in the folding apparatus 23 is applied. The concavoconvexity pitch then returns to the previous state before introduction of the assembly 5A into the folding apparatus 23. This changes the relative position between the recesses 51U and protrusions 53U of the upper nonwoven fabric sheet portion 6U and the protrusions 53L and recesses 51L of the lower nonwoven fabric sheet portion 6L. As a result, when the protrusions 53 enter into the recesses 51 at the sections where the recesses 51 and protrusions 53 were overlapping, and the tension on the upper nonwoven fabric sheet portion 6U is released to become the same as the tension on the lower nonwoven fabric sheet portion 6L, the concavoconvexity pitch of 25 the nonwoven fabric sheet portions 6U, 6L become offset by a half-pitch, starting from the sections where the protrusions 53 have entered into the recesses 51, such that the protrusions 53 enter into the recesses 51.

[0065]

The example given above is a production method using a folding apparatus 23. In a different example of the production method, two nonwoven fabric sheets are separately formed into the same shape and overlaid, so that a composite elastic member 5 as described above is produced without using the folding apparatus 23. In this case, when the nonwoven fabric sheets are overlaid together, higher tension is applied in the first direction D1 on one of the nonwoven fabric sheets than on the other nonwoven fabric sheet. This allows the same structure to be obtained as when two nonwoven fabric sheet portions 6U, 6L of the single nonwoven fabric sheet 6 are overlapped. This is because, for the reason explained above, the protrusions 53U, 53L of the nonwoven fabric sheet portions 6U, 6L enter into the recesses 51L, 51U of the nonwoven fabric sheet portions 6L, 6U.

However, it is to be understood that when the basis weights, fiber thicknesses, etc. of the two nonwoven fabric sheets differ from each other, it may be necessary to adjust the tension applied to each nonwoven fabric sheet so that the concavoconvexity pitches are mutual compatible .

[0066]

Returning to Fig. 6, the assembly 5B that has passed through the folding apparatus 23 is finally conveyed to the attachment press 25, and subjected to pressure in the thickness direction DT. This causes the nonwoven fabric sheet portions 6U, 6L to become joined together via the elastic members 7 in the non-concavoconvex regions 43, completing the final composite elastic member 5C.

[0067]

In this production example, the nonwoven fabric 26 sheet portions 6U, 6L are joined together via the elastic members 7 in the non-concavoconvex regions 43. As another example, however, the nonwoven fabric sheet portions 6U, 6L are joined at least partially via the elastic members 7 in the concavoconvex regions 41. As yet another example, the nonwoven fabric sheet portions 6U, 6L are joined at least partially in a manner not via the elastic members 7.

[0068]

Furthermore, with the composite elastic member 5, when the elastic members 7 are in the contracted state by the construction in which the nonwoven fabric sheet 6 has a cross-sectional undulating form in the concavoconvex regions 41, the thickness of the composite elastic member 5 in the concavoconvex regions 41 is greater than the thickness in the non-concavoconvex regions 43. The feel when the wearer has contacted the composite elastic member 5 is therefore satisfactory. This is because the non-concavoconvex regions 43 that have become hardened by the adhesive applied around the elastic members 7 protrude further than the concavoconvex regions 41, and the non-concavoconvex regions 43 contact with the skin surface of the wearer before the concavoconvex regions 41, preventing a feeling of foreign matter for the wearer. In order to prevent the wearer from sensing a feeling of foreign matter, the diameters of the elastic members 7 are more preferably smaller than the spacing between the non-concavoconvex regions 43 of the upper nonwoven fabric sheet portion 6U and the non-concavoconvex regions 43 of the lower nonwoven fabric sheet portion 6L, which are mutually aligned.

[0069]

Incidentally, as explained at the beginning of the description of this embodiment, the disposable diaper 1 of this embodiment has the composite elastic member 5 produced using the method described above provided in the waistband portion WP. According to this embodiment, the 27 composite elastic member 5 is disposed in the disposable diaper 1 in such a manner that the first direction D1 of the composite elastic member 5 is essentially aligned with the waistband direction DW. In other words, the composite elastic member 5 is disposed in the disposable diaper 1 so that the second direction D2 of the composite elastic member 5 matches the direction orthogonal to the waistband direction DW.

[0070]

For this embodiment, the ends of the composite elastic member 5 in the second direction D2, located on the waistband opening WO side, which are the portions folded on the folding lines FL, are mounted in the disposable diaper 1 so as to form the waistband portion edge WPE.

[0071] A function of the composite elastic member 5 provided in the waistband portion WP of the disposable diaper 1 of this embodiment will now be explained with reference to Fig. 13A to Fig. 14B.

[0072]

As mentioned above, the composite elastic member 5 has a design in which the recesses 51 and protrusions 53 are alternately formed in the first direction D1 in the concavoconvex regions 41. As will be understood from the front end cross-section shown in Fig. 5A, the cross-section along the first direction D1 of the concavoconvex regions 41 has an undulating cross-sectional form. Such an undulating form functions to reinforce the stiffness of the overall structure, similar to a cross-sectional undulating core provided inside a common corrugated board. Also, the concavoconvex regions 41 of the two nonwoven fabric sheet portions 6U, 6L are mutually adjacent, and more specifically, the protrusions 53U, 53L of the nonwoven fabric sheet portions 6U, 6L, having entered into the recesses 51L, 51U of the nonwoven fabric sheet portions 6L, 6U, the two nonwoven fabric sheet 28 portions 6U, 6L thus cooperate for mutual support. As a result, the stiffness against compressive force in the second direction D2 of the composite elastic member 5, and thus the direction orthogonal to the waistband direction DW, is higher than that of the composite elastic member 5' formed from the two nonwoven fabric sheet portions which have not been shaped.

[0073]

Fig. 13A and Fig. 13B are each a diagram showing an example of the form before and after the composite elastic member 5 of this embodiment has been compressed in the second direction D2. Fig. 13A and Fig. 13B show the state when the disposable diaper 1 is worn and the elastic members 7 are contracted to some degree, and as explained above, the concavoconvex regions 41 are stretched by the shaping apparatus 15 so that the thickness is greater than that of the non-concavoconvex regions 43. Fig. 14A and Fig. 14B are each a diagram showing an example of the form before and after the composite elastic member 5' formed from the two non-shaped nonwoven fabric sheet portions 6' has been compressed in the second direction. Even when compressive force has been applied in the second direction, the composite elastic member 5 is resistant to bending, i.e. resistant to buckling, by compressed stiffness due to the shaped form and structure at the concavoconvex regions 41. Referring to Fig. 13B, the composite elastic member 5 is shown being slightly bent at the non-concavoconvex regions 43, without bending at the concavoconvex regions 41. Referring to Fig. 14B, in contrast, at the non-shaped composite elastic member 5', application of compressive force in the second direction causes the non-shaped nonwoven fabric sheet portions 6' located between the elastic members 7 to freely move without generating force due to the shape, and therefore the spacings between the elastic members 7 are shortened. As this occurs, the non-shaped nonwoven fabric sheet 29 portions 6' protrude in the thickness direction, tending to easily form large wrinkles at the non-shaped composite elastic member 5'. It will therefore be understood that the composite elastic member 5 has higher compressive strength in the second direction D2 than a conventional composite elastic member 5'.

[0074]

The following compressive strength test was also conducted to confirm the high compressed stiffness of the composite elastic member 5.

[0075] - Test method -

The compressive strength test carried out for this purpose is a test similar to the ring crush test (JIS P8126) used in compressive strength testing for paper and paperboard. In this compressive strength test, as shown in Fig. 15A, a test strip 61 having a shape with lengths of 100 mm in the first direction and 20 mm in the second direction is prepared. As shown in Fig. 15B, the test strip 61 is then formed into a ring, and the 2 mm overlapping portion of the edges is held and joined at one location at approximately the center using a stapler (the stapler needle 63 being shown in Fig. 15B).

[0076]

To carry out the compressive strength test, the test strip 61 is mounted on a test stage and compressive force is applied downward in the vertical direction onto the entire upper edge of the test strip 61, at a speed of 10 mm/min until the test strip 61 buckles. Fig. 16 is a graph showing an example of changes in time T[s] and compressive force Fc[N] in the compressive strength test. Referring to Fig. 16, it will be understood that compressive force is gradually applied to the test strip 61, after which the test strip 61 becomes no longer able to withstand the compressive force and buckles, at the point indicated by reference numeral 65 in Fig. 16. The maximum compressive force applied at the buckling point 30 is used as the evaluation standard in the compressive strength test.

[0077]

This compressive strength test was carried out for the samples described below.

[0078] (Example)

The test strip 61 of the example was fabricated from a composite elastic member 5 produced by a production method similar to the production method example described above, and the same test strip 61 size mentioned above was used. In the example test strip 61, the nonwoven fabric sheet 6 used was an SMS nonwoven fabric shaped with a uniform concavoconvexity pitch by a shaping apparatus 15 having a spacing of 1 mm between the top sections of adjacent teeth 27, 29, the spacing between elastic members 7 being a constant 5 mm, and the weight being 15 g/m2.

[0079] (Comparative Example)

There was used a composite elastic member 5' fabricated in exactly the same manner as the composite elastic member 5, except for using a non-shaped nonwoven fabric sheet portion 6', and it was cut to the same size as the test strip 61 described above.

[0080]

The results of the compressive strength test are shown below. The following measurement results are average values for the measurement results for three test strips for both the example and comparative example.

[0081] [Table 1]

Example Comparative Example Compressive strength 0.58 0.39 [0082] 31

As shown in Table 1, the composite elastic member 5 of the example fabricated as described above was confirmed to have sufficiently higher compressive strength in the second direction than the composite elastic member of the comparative example which had not been shaped.

[0083]

Also, a shorter spacing between elastic members 7 resulted in higher compressive strength of the composite elastic member 5. This is because in an object having a constant cross-sectional area, a greater length of the object is associated with lower resistance to buckling load (load in the lengthwise direction of the object).

For example, if the portion of the nonwoven fabric sheet 6 at one concavoconvexity pitch distance having an undulating cross-section between two adjacent elastic members 7 is considered to be one column, the force considered is the application of force compressing the column in the lengthwise direction of the column. In the field dealing with strength of materials, since the buckling stress of the column having a constant cross-sectional shape is a higher buckling stress with a smaller column length, it may be said that a shorter spacing between elastic members 7 is associated with higher compressive strength of the composite elastic member 5.

[0084]

The function and effect of the disposable diaper 1 of this embodiment will now be explained.

[0085] (1) In the waistband portion WP of the disposable diaper 1 of this embodiment, the spacing LL between elastic members 7 situated in the leg opening side areas ALO is larger than the spacing LW between elastic members 7 situated in the waistband opening side area AWO. When the disposable diaper 1 is formed in this manner, it is easier to lift the disposable diaper 1 when it is fitted 32 onto a wearer. The reason for this is as follows. When the disposable diaper 1 is fitted onto a wearer, a finger is inserted between the waistband portion WP and the skin surface of the wearer. When the finger is thus inserted, the compressive strength is high on the waistband portion WP in the waistband opening side area AWO which is previously contacted with the finger, making deformation such as curling less likely at that portion, and therefore the finger is easily inserted between the waistband portion WP and the skin surface of the wearer. Moreover, when the inserted finger reaches the leg opening side area ALO, the fingertip enters the waistband portion WP in the leg opening side area ALO, in order to lift the disposable diaper 1. During this time, the elastic force is weak at the waistband portion WP of the leg opening side area ALO because of the wide spacing between the elastic members 7, and even though the nonwoven fabric sheet 6 portion of the composite elastic member 5 has been shaped, it is readily deformable compared to the waistband portion WP in the waistband opening side area AWO. Furthermore, the fingertip easily enters between the regions AWO, ALO, aided by the difference in stiffness between the regions AWO, ALO, allowing the lifting force to be efficiently transmitted to the waistband portion WP. Thus, as explained above, the disposable diaper 1 of this embodiment is easy to lift.

[0086] (2) Furthermore, since the compressive strength of the waistband portion WP of the waistband opening side area AWO can be increased without placing any additional member such as used in the invention described in PTL 1, it is possible to limit increase in production costs.

[0087] (3) In addition, the composite elastic member 5 preferably has a superior feel from the viewpoint of contact on the skin of the wearer. Compared to a non-33 shaped composite elastic member 5' as described above, the composite elastic member 5 of this embodiment is thinner overall and has a smoother surface since it has been regularly shaped, and therefore the contact area with the skin surface is low. Moreover, as mentioned above, the thickness of the composite elastic member 5 in the contracted state is thicker at the concavoconvex regions 41 than at the non-concavoconvex regions 43, and therefore the non-concavoconvex regions 43 that are hard due to the adhesive applied around the elastic members 7 do not directly contact with the skin of the wearer.

This results in a satisfactory feel when the composite elastic member 5 has been contacted. From this viewpoint, in order to further smooth the surface of the composite elastic member 5, it is preferred for the concavoconvexity pitch in the concavoconvex regions 41 to be even smaller.

[0088] (4) In addition, as mentioned above, in the disposable diaper 1 of this embodiment, more preferably the distance LEB in the direction orthogonal to the waistband direction DW between the back waistband portion edge WPEB of the waistband portion WP and the lengthwise edge 3EB of the absorbing element located on the back waistband portion edge WPEB side, is longer than the distance LES in the direction orthogonal to the waistband direction DW between the stomach waistband portion edge WPES and the lengthwise edge 3ES of the absorbing element located on the stomach waistband portion edge WPES side. This will allow the leg opening side area ALO to be wider in the back side portion WPB of the waistband portion WP, so that the fingertip can even more easily enter when the back side portion WPB of the waistband portion WP is gripped, which requires greater force when lifting the disposable diaper 1. As a result, the disposable diaper 1 of this embodiment is even easier to lift.

[0089] 34 (5) Furthermore, the disposable diaper 1 of this embodiment more preferably has the elastic members 7 of the composite elastic member 5 provided at locations that overlap with the location where the absorbing element 3 is present. This will allow force applied to the composite elastic member 5 to be transmitted to the absorbing element 3 not only via the nonwoven fabric sheet 6 but also by the elastic members 7. As a result, the disposable diaper 1 will be even easier to lift.

[0090] (6) In addition, the composite elastic member 5 has a superior aesthetic appearance from the viewpoint of visibility from the outer side. The disposable diaper 1 of this embodiment is thin overall, with a smoother surface and a high aesthetic appearance, by formation of shaped regular wrinkles even in the contracted state, due to the construction of the composite elastic member 5 wherein the protrusions 53 enter into the recesses 51.

[0091]

Furthermore, the elastic member attachment factor of the elastic members 7 located in the leg opening side area ALO of the waistband portion WP is preferably lower than the elastic member attachment factor of the elastic members 7 located in the waistband opening side area AWO of the waistband portion WP. This anchors the disposable diaper 1 to the wearer by stronger elastic force by the elastic members 7, in the waistband opening side area AWO of the waistband portion WP. In the leg opening side area ALO of the waistband portion WP, on the other hand, relaxation of constriction by the elastic members 7 facilitates movement of the waistband portion WP at the leg opening side area ALO. This allows a finger inserted into the disposable diaper 1 from between the waistband opening WO and the skin surface of the wearer to easily enter into the waistband portion WP. As a result, the disposable diaper 1 will be even easier to lift. Incidentally, when the elastic members 7 are disposed on 35 the border line between the waistband opening side area AWO and the leg opening side area ALO, the elastic member attachment factor of the elastic members 7 is the same as both of the elastic member attachment factors of the elastic members 7 located in the waistband opening side area AWO and leg opening side area ALO.

[0092]

All features that will be readily appreciated by a person skilled in the art from the present specification, the drawings and the description in the claims, though explained only in combinations related with certain other features throughout the present specification, may be employed either independently, or one or more of the disclosed features may be combined in any desired combination, so long as the features are not distinctly excluded and so long as the technical mode is not impossible or the combination is not meaningless.

[0093]

In the disposable diaper 1 of the embodiment described above, in both the stomach side portion WPS of the waistband portion WP and the back side portion WPB of the waistband portion WP, the construction is such that the spacing LL between the elastic members 7 located in the leg opening side area ALO is larger than the spacing LW between the elastic members 7 located in the waistband opening side area AWO. According to another embodiment, the elastic members 7 are disposed with a construction such that the spacing LL is larger than the spacing LW in either the stomach side portion WPS or the back side portion WPB of the waistband portion WP. Moreover, a smaller spacing LL, LW between the elastic members 7 in the waistband opening side area AWO and the leg opening side area ALO is preferred as this will increase the compressive strength.

[0094]

In this embodiment, the waistband opening side area AWO includes the waistband portion edge WPE forming the 36 waistband opening WO, but it may instead be separated from the waistband opening WO in the direction orthogonal to the waistband direction DW, so as not to include the waistband portion edge WPE. That is, a separate area may be present between the waistband opening side area AWO and the waistband opening WO. Moreover, the leg opening side area ALO is adjacent to the waistband opening side area AWO in the direction orthogonal to the waistband direction DW, but it may also be separated from the waistband opening side area AWO. In other words, a separate area may be present between the leg opening side area ALO and the waistband opening side area AWO.

[0095]

For example, the disposable diaper 1 according to another embodiment may comprise a waistband portion WP including three areas, the areas being defined as the first area, second area and third area from the waistband opening WO side, from the waistband opening WO toward the periphery of the leg openings LO. Here, the spacing between the elastic members situated in the second area is longer than the spacing between the elastic members situated in the first area, and the spacing between the elastic members situated in the third area is longer than the spacing between the elastic members situated in the second area. In this case, the first area is the waist opening side area and the second area is the leg opening side area, based on the relationship between the elastic members 7 in the areas. Similarly, the second area may be the waist opening side area and the third area may be the leg opening side area. Also similarly, the first area may be the waist opening side area and the third area may be the leg opening side area.

[0096]

In the disposable diaper 1 of this embodiment, the distance LEB in the direction orthogonal to the waistband direction DW between the back waistband portion edge WPEB of the waistband portion WP and the lengthwise edge 3EB 37 of the absorbing element located on the back waistband portion edge WPEB side, is longer than the distance LES in the direction orthogonal to the waistband direction DW between the stomach waistband portion edge WPES and the lengthwise edge 3ES of the absorbing element located on the stomach waistband portion edge WPES side. According to another embodiment, however, the distance LEB is shorter than the distance LES. According to yet another embodiment, the distance LEB is the same as the distance LES.

[0097]

In the disposable diaper 1 of this embodiment, the elastic members 7 of the composite elastic member 5 situated in the waistband portion WP are each formed across the entire waistband direction DW of the waistband portion WP. In a disposable diaper 1 according to yet another embodiment, a graphics sheet is provided containing characters of the manufacturer's name or product name, or illustrations such as characters or marks, in a common manner, and the composite elastic member 5 is provided over the graphics sheet. In a composite elastic member 5 provided on a disposable diaper 1 of this embodiment, the elastic members 7 are not disposed in the graphics area on which the graphics sheet is provided, in order to improve visibility of the characters or illustrations on the graphics sheet. Generally, during production of the composite elastic member 5, the adhesive will not be applied onto the elastic members 7 situated in the portions corresponding to the graphics area, so that the elastic members 7 will not be situated in the graphics area. Moreover, after the elastic members 7 have been attached to the nonwoven fabric sheet 6, the elastic members 7 are cut at the portions where the adhesive has not been applied. In a common disposable diaper, the graphics area is usually situated at a location at the center section in the waistband direction DW of the stomach side portion WPS 38 and the back side portion WPB in the waistband portion WP, and overlapping the absorbing element 3. Thus, even when the elastic members 7 are partially not situated in the waistband portion WP, the elastic members 7 are preferably provided at locations where the portions that can actually exhibit the elastic force of the elastic members 7 overlap with the absorbing element 3. This is in order to allow the force of lifting the disposable diaper 1 to be transmitted from the waistband portion WP to the absorbing element 3 through the elastic members 7, and to thus facilitate lifting of the disposable diaper 1. Furthermore, according to another embodiment, the elastic members 7 of the composite elastic member 5 are provided at locations that overlap with the locations where the absorbing element 3 is present.

[0098]

Also, in order to improve the visibility of the graphics area, the recesses 51 and protrusions 53 may not be shaped in the nonwoven fabric sheet portion 6 at the sections overlapping with the graphics area. However, preferably the entire waistband portion WP is shaped, as in the embodiment described above. This will allow the effect of the invention to be more reliably exhibited.

[0099]

In the embodiment described above, the elastic members 7 are provided between the non-concavoconvex regions 43 of the inner side nonwoven fabric sheet portion 6U and the non-concavoconvex regions 43 of the outer side nonwoven fabric sheet portion 6L. According to another embodiment, however, the elastic members 7 are provided between the concavoconvex regions 41 of the inner side nonwoven fabric sheet portion 6U and the concavoconvex regions 41 of the outer side nonwoven fabric sheet portion 6L.

[0100]

In this embodiment, in the concavoconvex regions 41, the protrusions 53L of the outer side nonwoven fabric 39 sheet portion 6L enter into the recesses 51U of the inner side nonwoven fabric sheet portion 6U, and the protrusions 53U of the inner side nonwoven fabric sheet portion 6U enter into the recesses 51L of the outer side nonwoven fabric sheet portion 6L. According to yet another embodiment, however, the protrusions 53L of the outer side nonwoven fabric sheet portion 6L do not enter into the recesses 51U of the inner side nonwoven fabric sheet portion 6U, and the protrusions 53U of the inner side nonwoven fabric sheet portion 6U do not enter into the recesses 51L of the outer side nonwoven fabric sheet portion 6L.

[0101]

In this embodiment, the inner side nonwoven fabric sheet portion 6U and the outer side nonwoven fabric sheet portion 6L are formed from a single nonwoven fabric sheet, but according to another embodiment, the inner side nonwoven fabric sheet portion 6U and the outer side nonwoven fabric sheet portion 6L are formed from separate nonwoven fabric sheets, the nonwoven fabric sheets being not folded.

[0102]

In a disposable diaper 1 according to this embodiment, the waistband portion edge WPE of the waistband portion WP forming the waistband opening WO is formed by the folded portions of the single nonwoven fabric sheet 6 at the folding lines FL, and the portions of the single nonwoven fabric sheet 6 folded over from the waistband portion edge WPE do not overlap the absorbing element 3. According to another embodiment, however, the portions of the single nonwoven fabric sheet 6 folded over from the waistband portion edge WPE overlap the absorbing element 3.

[0103]

The present invention is prescribed as follows.

[0104] (1) A disposable diaper in which a waistband opening 40 and a pair of leg openings are formed and which has an absorbing element having a liquid-permeable top sheet, a liquid-impermeable back sheet and a liquid-absorbing absorbent body lying between the top sheet and the back sheet, the disposable diaper comprising a waistband portion, provided between the waistband opening and the leg openings of the disposable diaper, that covers the waist of the wearer, and a crotch portion, forming the leg openings together with the waistband portion, that covers the crotch of the wearer, a composite elastic member being formed in the waistband portion, the composite elastic member comprising a first nonwoven fabric sheet section and a second nonwoven fabric sheet section which are mutually overlaid, and a plurality of elastic members extending in the waistband direction between the first nonwoven fabric sheet section and the second nonwoven fabric sheet section, the first nonwoven fabric sheet section and the second nonwoven fabric sheet section each comprising: a plurality of concavoconvex regions at least partially comprising protrusions and recesses that alternately repeat along the waistband direction and extend in the direction orthogonal to the waistband direction, and at least one non-concavoconvex region that separates the concavoconvex regions from each other in the direction orthogonal to the waistband direction, and the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are overlaid in such a manner that the concavoconvex regions of the first nonwoven fabric sheet section and the concavoconvex regions of the second nonwoven fabric sheet section are mutually aligned and the non-concavoconvex region(s) of the first nonwoven fabric sheet section and the non-concavoconvex region(s) of the second nonwoven fabric sheet section are mutually aligned, 41 the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are joined together through the elastic member, the waistband portion includes a waistband opening side area located on the waistband opening side and leg opening side areas located further to the leg opening sides than the waistband opening side area, and the spacing between the elastic members situated in the leg opening side areas is larger than the spacing between the elastic members situated in the waistband opening side area.

[0105] (2) A disposable diaper according to (1), the waistband portion including a waistband portion edge that forms the waistband opening, the waistband portion edge including a stomach waistband portion edge located on the stomach side of the wearer when the disposable diaper is used, and a back waistband portion edge located on the back side of the wearer when the disposable diaper is used, the crotch portion being provided extending from the stomach side portion of the waistband portion to the back side portion of the waistband portion, in a manner such that the absorbing element is along the lengthwise direction of the crotch portion, and the distance between the back waistband portion edge and the lengthwise edge of the absorbing element located on the back waistband portion edge side, in the direction orthogonal to the waistband direction, being longer than the distance between the stomach waistband portion edge and the lengthwise edge of the absorbing element located on the stomach waistband portion edge side, in the direction orthogonal to the waistband direction.

[0106] (3) A disposable diaper according to (1) or (2) , wherein the elastic members of the composite elastic member are provided at locations that overlap with the 42 location where the absorbing element is present.

[0107] (4) A disposable diaper according to any one of (1) to (3), wherein the elastic member attachment factor of the elastic members located in the leg opening side areas of the waistband portion is lower than the elastic member attachment factor of the elastic members located in the waistband opening side area of the waistband portion.

[0108] (5) A disposable diaper according to any one of (1) to (4) , wherein the elastic members are disposed between the non-concavoconvex region of the first nonwoven fabric sheet section and the non-concavoconvex region of the second nonwoven fabric sheet section.

[0109] (6) A disposable diaper according to any one of (1) to (5), wherein the protrusions of the first nonwoven fabric sheet section enter into the recesses of the second nonwoven fabric sheet section, and the protrusions of the second nonwoven fabric sheet section enter into the recesses of the first nonwoven fabric sheet section.

[0110] (7) A disposable diaper according to any one of (1) to (6), wherein the first nonwoven fabric sheet section and the second nonwoven fabric sheet section which are mutually overlaid are formed by folding a single nonwoven fabric sheet along folding lines that are parallel in the waistband direction, and mutually overlaying them.

[0111] (8) A disposable diaper according to (7), wherein the waistband portion edge of the waistband portion forming the waistband opening is formed by the folded portions of the single nonwoven fabric sheet 43 folded at the folding lines, and the portions of the single nonwoven fabric sheet folded from the waistband portion edge do not overlap with the absorbing element.

[0112] (9) A disposable diaper according to any one of (1) to (8), wherein the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are joined by an adhesive applied onto the elastic member.

Explanation of Symbols [0113] 1 Disposable diaper 3 Absorbing element 3B Back sheet 3C Absorbent body 3T Top sheet 5 Composite elastic member 6 Nonwoven fabric sheet 6U Upper nonwoven fabric sheet portion and inner side nonwoven fabric sheet portion (first nonwoven fabric sheet section or second nonwoven fabric sheet section) 6L Lower nonwoven fabric sheet portion and outer side nonwoven fabric sheet portion (second nonwoven fabric sheet section or first nonwoven fabric sheet section) 7 Elastic member 41 Concavoconvex region 43 Non-concavoconvex region 51 Recess 53 Protrusion AWO Waistband opening side area ALO Leg opening side area CP Crotch portion DW Waistband direction LO Leg opening WO Waistband opening WP Waistband portion

Claims

1. A disposable diaper in which a waistband opening and a pair of leg openings are formed and which has an absorbing element having a liquid-permeable top sheet, a liquid-impermeable back sheet and a liquidabsorbing absorbent body lying between the top sheet and the back sheet, the disposable diaper comprising a waistband portion, provided between the waistband opening and the leg openings of the disposable diaper, that covers the waist of the wearer, and a crotch portion, forming the leg openings together with the waistband portion, that covers the crotch of the wearer, a composite elastic member being formed in the waistband portion, the composite elastic member comprising a first nonwoven fabric sheet section and a second nonwoven fabric sheet section which are mutually overlaid, and a plurality of elastic members extending in the waistband direction between the first nonwoven fabric sheet section and the second nonwoven fabric sheet section, the first nonwoven fabric sheet section and the second nonwoven fabric sheet section each comprising : a plurality of concavoconvex regions at least partially comprising protrusions and recesses that alternately repeat along the waistband direction and extend in the direction orthogonal to the waistband direction, and at least one non-concavoconvex region that separates the concavoconvex regions from each other in the direction orthogonal to the waistband direction, and the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are overlaid in such a manner that the concavoconvex regions of the first nonwoven fabric sheet section and the concavoconvex regions of the second nonwoven fabric sheet section are mutually aligned and the non-concavoconvex region(s) of the first nonwoven fabric sheet section and the non-concavoconvex region(s) of the second nonwoven fabric sheet section are mutually aligned, the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are joined together through the elastic member, the waistband portion includes a waistband opening side area located on the waistband opening side and leg opening side areas located further to the leg opening sides than the waistband opening side area, and the spacing between the elastic members situated in the leg opening side areas is larger than the spacing between the elastic members situated in the waistband opening side area.

2. A disposable diaper according to claim 1, the waistband portion including a waistband portion edge that forms the waistband opening, the waistband portion edge including a stomach waistband portion edge located on the stomach side of the wearer when the disposable diaper is used, and a back waistband portion edge located on the back side of the wearer when the disposable diaper is used, the crotch portion being provided extending from the stomach side portion of the waistband portion to the back side portion of the waistband portion, in such a manner that the absorbing element is along the lengthwise direction of the crotch portion, and the distance between the back waistband portion edge and the lengthwise edge of the absorbing element located on the back waistband portion edge side, in the direction orthogonal to the waistband direction, being longer than the distance between the stomach waistband portion edge and the lengthwise edge of the absorbing element located on the stomach waistband portion edge side, in the direction orthogonal to the waistband direction.

3. A disposable diaper according to claim 1 or 2, wherein the elastic members of the composite elastic member are provided at locations that overlap with the location where the absorbing element is present.

4. A disposable diaper according to any one of claims 1 to 3, wherein the elastic member attachment factor of the elastic members located in the leg opening side areas of the waistband portion is lower than the elastic member attachment factor of the elastic members located in the waistband opening side area of the waistband portion.

5. A disposable diaper according to any one of claims 1 to 4, wherein the elastic members are disposed between the non-concavoconvex region of the first nonwoven fabric sheet section and the non-concavoconvex region of the second nonwoven fabric sheet section.

6. A disposable diaper according to any one of claims 1 to 5, wherein the protrusions of the first nonwoven fabric sheet section enter into the recesses of the second nonwoven fabric sheet section, and the protrusions of the second nonwoven fabric sheet section enter into the recesses of the first nonwoven fabric sheet section.

7. A disposable diaper according to any one of claims 1 to 6, wherein the first nonwoven fabric sheet section and the second nonwoven fabric sheet section which are mutually overlaid are formed by folding a single nonwoven fabric sheet along folding lines that are parallel in the waistband direction, and mutually overlaying them.

8. A disposable diaper according to claim 7, wherein the waistband portion edge of the waistband portion forming the waistband opening is formed by the folded portions of the single nonwoven fabric sheet folded at the folding lines, and the portions of the single nonwoven fabric sheet folded from the waistband portion edge do not overlap with the absorbing element.

9. A disposable diaper according to any one of claims 1 to 8, wherein the first nonwoven fabric sheet section and the second nonwoven fabric sheet section are joined by an adhesive applied onto the elastic member.