PH12016500186B1

PH12016500186B1 - Disposable diaper

Info

Publication number: PH12016500186B1
Application number: PH12016500186A
Authority: PH
Inventors: Satoru Sakaguchi; Yasuhiro Yamanaka; Kana Sawa; Maki Miyake
Original assignee: Unicharm Corp
Priority date: 2013-07-26
Filing date: 2016-01-26
Publication date: 2016-05-02
Also published as: CN105407849B; TWI661816B; KR20160037885A; AU2014294292B2; CN105407849A; TW201529056A; AU2014294292A1; PH12016500186A1; SA516370469B1; KR102312228B1; JP6193666B2; WO2015012129A1; JP2015024048A; MY168983A

Abstract

A disposable diaper (10) includes a pair of fastening tapes (90) disposed on product widthwise outer ends of the back lower-torso region and configured to be fastened to the front lower-torso region, and a waist elastic sheet extending bilaterally from the center in the product width direction of the disposable diaper and being elastically extensible in the product width direction. The waist elastic sheet includes a back waist elastic sheet disposed at a back end (10R) of the diaper. When the disposable diaper is in a relaxed state, the back end (10R) of the disposable diaper has a curved shape in which the product widthwise center is recessed inward in the product longitudinal direction from the product widthwise outer ends.

Description

follows: leg elastic zone's extensibility = (length of leg elastic zone in stretched state)/(length of leg elastic zone in relaxed state).

Further, the extensibility of the secondary elastic zone 77 is preferably 1.6 to 2.4. ltis noted that, the extensibility of the secondary elastic zone 77 is a degree of extension of the secondary elastic zone and is defined as follows: secondary elastic zone's extensibility = (length of secondary elastic zone in stretched state)/(length of secondary elastic zone in relaxed state).

In this description, such extensibility is determined as follows, for example.

First, the disposable diaper 10 is taken out of a package if it is enclosed therein.

A region to be measured, for example, the leg elastic zone, is then cut out. Here, the external sheet joined to the region to be measured such as the leg elastic zone, is cut out altogether. The extensibility of the cut sample is measured to determine the extensibility of the region of interest.

Each sample is kept in an atmosphere at a temperature of 20°C + 2°C and a relative humidity (RH) of 60% + 5% for 60 minutes, and then the length of the region of interest is measured along the elastically extensible direction. This length measured is defined as "the length of the region of interest (for example, the leg elastic zone) in the relaxed state."

Secondly, the length of the desired region in the elastically extensible direction is measured in this state (i.e., the relaxed state), and the length of this desired region in the elastically extensible direction, as the region is stretched from the relaxed state to an extent that any wrinkle created by the elastic member is not visually observed in a non-extensible sheet, are measured. This latter length measured is defined as "the length of the region of interest (for example, the leg elastic zone) in the stretched state.”

Using these measurements, extensibility can be calculated in the above expressions.

It is noted that measurement of "length" herein is intended to take the following ee approach.

A sample is prepared by taking out the disposable diaper 10 from a package if it is enclosed therein and keeping it in an atmosphere at a temperature of 20°C + 2°C and a relative humidity (RH) of 60% + 5% for 12 hours.

Next, a measuring tape (PVC-coated fiberglass tape; available from Shinwa

Rules Co. Ltd.) is used along the region to be measured, and the length of the region as such is measured. To measure the length of the region of interest in the stretched state, the disposable diaper 10 in the relaxed state is stretched to an extent that any wrinkle created by the elastic member is not visually observed.

In this description, lengths of ten samples were measured according to the above approach, and an average value was calculated, which was defined as length.

Further, a pair of leg side gathers 80, extending in the product longitudinal direction L, is disposed inboard from the pair of leg elastic zones 75 (that is, toward the center in the product width direction W). The leg side gathers 80 are raised elastic gathers, disposed along product widthwise inner ends of the side flaps 70 and inboard in the product width direction from the leg elastic zones 75. The leg side gathers 80 are disposed inboard in the product width direction from the leg elastic zones 75. The leg side gathers 80 can employ any known configurations, specifically, they may be formed by sheet materials different from the side flaps 70.

The disposable diaper 10 has a waist elastic sheet that extends bilaterally from the product widthwise center of the disposable diaper and is elastically extensible in the product width direction. The waist elastic sheet includes a back waist elastic sheet 85 disposed at the back end of the disposable diaper and a front waist elastic sheet 86 disposed at the front end of the disposable diaper. It is noted that, in Fig. 1, an imaginary line L1 is shown, running through the product widthwise center (midpoints) of the disposable diaper, extending in the product longitudinal direction.

When the disposable diaper is in the relaxed state, the back end 10R thereof has a curved shape in which the product widthwise center of the back end 10R is recessed inward in the product longitudinal direction from the product widthwise outer ends of the back end 10R. When the disposable diaper is in the relaxed state, a back end of the back waist elastic sheet 85 at the back end of the disposable diaper has a curved shape in which the product widthwise center is recessed inward in the product longitudinal direction from the product widthwise outer ends.

Further, when the disposable diaper is in the stretched state (as is shown in Fig. 1), a front end 85F of the back waist elastic sheet 85 has a curved shape in which the product widthwise center of the front end 85F is recessed outward in the product longitudinal direction from the product widthwise outer ends of the front end 85F. It is noted that, the curved shape of the back waist elastic sheet is not formed in the entirety of the front end 85F, but partially at the widthwise center of the front end.

The back waist elastic sheet 85 is disposed between the pair of fastening tapes in the product width direction. The front end 85F of the back waist elastic sheet 85 partially overlaps the absorbent. The back end 85R of the back waist elastic sheet 85 is aligned with the back end of the disposable diaper. The back waist elastic sheet 85 is greater in length in the product width direction than the absorbent 40 and the back sheet 60a. The back waist elastic sheet extends outward in the product width direction from the absorbent 40 and from the back sheet 60a.

When the disposable diaper is in the relaxed state, the front end 10F thereof has a curved shape in which the product widthwise center of the front end 10F is recessed inward in the product longitudinal direction from the product widthwise outer ends the front end 10F. When the disposable diaper is in the relaxed state, a front end 86F of the front waist elastic sheet 86 at the front end of the disposable diaper has a curved shape in which the product widthwise center of the front end 86F is recessed inward in the product longitudinal direction from the product widthwise outer ends of the front end 86F.

Further, when the disposable diaper is in the stretched state (as is shown in Fig. 1), a back end 86R of the front waist elastic sheet 86 has a curved shape in which the product widthwise center of the back end 86R is recessed outward in the product longitudinal direction from the product widthwise outer ends of the back end 86R. lt is noted that, the curved shape of the front waist elastic sheet is not formed in the entirety of the back end 86R, but partially at the widthwise center of the back end 86R.

The back end 86R of the front waist elastic sheet 86 is adjacent to the absorbent 40 and the target sections 95 in the product longitudinal direction. The back end 86R of the front waist elastic sheet 86 is outboard in the product longitudinal direction from the absorbent 40 and from the target sections 95.

The front end 86F of the front waist elastic sheet 86 is aligned with the front end of the disposable diaper. The front waist elastic sheet 86 is greater in length in the product width direction than the absorbent 40 and the back sheet 60a. The front waist elastic sheet 86 extends outward in the product width direction from the absorbent 40 and from the back sheet 60a.

In the embodiment, a sheet having a property of narrowing (so-called "narrowing sheet") is preferable for the waist elastic sheet, that is, when the sheet is stretched in one direction, the sheet is narrowed in a second direction orthogonal to the stretching direction.

A usable waist elastic sheet can be a sheet formed of an mixture of elastic : filaments that are elastically extensible and non-elastic filaments that are non-elastically extensible, in particular, a spunbond nonwoven fabric sheet having a mass of 20 to 80 g/m® more preferably 40 to 75 g/m? and further more preferably 50 to 70 g/m? containing polyurethane filaments as elastic filaments having a denier of 2 to 6 dtex and at least one of polyolefin filaments, polyester filaments, and polyamide filaments as non-elastic filaments having a denier of 2 to 6 dtex. with a mixing ratio by weight between the elastic filaments and the non-elastic filaments being 40 : 60 to 60 : 40. In such nonwoven fabric formed of a mixture of elastic filaments and non-elastic filaments, part of a non-elastic filament layer is broken with gear so as to render extensibility. Other waist elastic sheets are also possible as long as one has a narrowing property, which can be relatively readily shaped into the narrowed configuration of the embodiment. It is noted that, the waist elastic sheet is not limited to a nonwoven fabric sheet, but may be formed of a film sheet. Further, a pre-shaped elastic sheet may also be used, having a varying width in the product longitudinal direction (cut so as to protrude inward) in the product longitudinal direction.

The extensibility of the back waist elastic sheet 85 is preferably 1.4 to 1.8. In the embodiment, the extensibility of the back waist elastic sheet 85 is setto 1.5t0 1.6. It is noted that, the extensibility is a degree of extension of the back waist elastic sheet and is defined as follows: back waist elastic sheet's extensibility = (length of back waist elastic sheet in stretched state)/(length of back waist elastic sheet in relaxed state).

The extensibility of the front waist elastic sheet 86 is preferably 1.3 to 1.7. In the embodiment, the extensibility of the front waist elastic sheet 86 is setto 1.4t0 1.6. It is noted that, the extensibility is a degree of extension of the front waist elastic sheet and is defined as follows: front waist elastic sheet's extensibility = (length of front waist elastic sheet in stretched state)/(length of front waist elastic sheet in relaxed state).

In the embodiment, the waist elastic sheet is interposed between the external sheet 60 and the back sheet 60a. However, in a configuration in which the core wrap 40b extends outward in the product longitudinal direction from the absorbent core 40a, the waist elastic sheet may be interposed between the core wrap 40b and the back sheet 60a or the external sheet 60. The position of the waist elastic sheet is not limited. In the region in which the absorbent is absent, the waist elastic sheet may be interposed between the side flap 70 and the back sheet 60a or the external sheet 60.

The back waist elastic sheet 85, in plan view of the disposable diaper, overlaps a portion of the low-stiffness region 110 of the absorbent. It is noted that, although the back waist elastic sheet 85 partially overlaps the low-stiffness region 110 in the embodiment, the whole back waist elastic sheet 85 may overlap the low-stiffness region

Because such low-stiffness region 110 has been formed, the back waist elastic sheet 85 can elastically extend without obstruction, and when it contracts, the low-stiffness region 110 becomes narrower, making the distance between the planking absorbent areas in the product width direction shorter than the low-stiffness region 110, so that the absorbent 40 is prevented from rising into an unintended profile. It is noted that, the low-stiffness region 110 is preferably narrower in width than the back waist elastic sheet 85 in order to prevent leakage of bodily waste.

It is noted that, although the waist elastic sheet according to the embodiment is configured to extend and contract in the product width direction, the waist elastic sheet may be configured to extend and contract in the product width direction and the product longitudinal direction.

The fastening tape 90 is attached to the region in the side flap 70 corresponding to the back lower-torso region 30. The fastening tape 90 includes a substrate sheet 91 connected to the side flap 70 and a hook sheet 92 fixed to the substrate sheet 91 and provided with a plurality of engagement hooks as engagement members (not shown) thereon. The hook sheet 92 is the region that is provided with engagement members thereon; and the waist holding section in the back lower-torso region, as mentioned above, is the region that extends from the hook sheet 92 in the product width direction.

The hook sheet 92 is fixed to the substrate sheet 91, more particularly, joined to the substrate sheet 91. The joining of the hook sheet 92 and the substrate sheet 91 is preferably performed with care to avoid stiffening of the fastening tape 90 more than necessary. Specifically, the hook sheet 92 and the substrate sheet 91 are preferably joined with hot melt adhesive, applied intermittently in dots, spirals, or linearly. It is noted that the hook sheet 92 and the substrate sheet 91 may also be joined via heat sealing or the like.

The substrate sheet 91 is formed by one or more laminated nonwoven fabrics.

A nonwoven fabric made through spunbonding (SB) or spunbond-meltblown-spunbond

(SMS) process may be used as the substrate sheet 91. The nonwoven fabric forming the substrate sheet 91 has a basis weight (or a total basis weight if nonwoven fabrics are laminated) of 30 to 120 g/m?, preferably 40 to 90 g/m.

The fastening tape includes a base 93 that overlaps the external sheet and an extension 94 that extends outward in the product width direction from the external sheet.

The base 93 is an area of the substrate sheet 91 which overlaps the external sheet when the fastening tape is deployed. The extension 94 is another area of the substrate sheet 91 which does not overlap the external sheet. When the disposable diaper is in the stretched state as is shown in Fig. 1, a product longitudinal center of the extension is aligned with a product longitudinal center of the base, in the product longitudinal direction.

On the other hand, when the disposable diaper is in the relaxed state, the fastening tape is shifted in association with the curving of the back waist elastic sheet 85, so that the product longitudinal center of the extension comes outboard in the product longitudinal direction from the product longitudinal center of the base.

As used herein, overlapping of components includes indirect overlapping of components (with other component(s) interposed therebetween) as well as direct overiapping of components.

The target sections 95 are disposed on the non-skin-facing surface of the external sheet 60 in the front lower-torso region. The target sections 95 are configured to function as a loop in a hook-loop fastening system so that the engagement hooks of the fastening tapes can hook thereon. An air-through nonwoven fabric, for example, may be used for the target zones.

By way of example, a filament nonwoven fabric made of polyolefinic thermoplastic synthetic resin filaments or a polyolefinic thermoplastic synthetic resin film may be used for the target sections 95. The loops on the target sections may be formed of polyolefinic thermoplastic synthetic resin.

Further, a bulky nonwoven fabric may be partially embossed for preventing fluffiness on the surface and used for the target sections 95.

Further, the external sheet 60 of the disposable diaper may be formed by a nonwoven fabric, and indicial marking for the fastening of the fastening tapes 90 may be printed on the non-skin-facing surface of the back sheet 60a or the external sheet 60 or indicial sheets may be disposed on the non-skin-facing surface of the back sheet 60a or the external sheet 60, so that the marking or the sheets function as the target sections.

Next, a worn state of the disposable diaper formed as above will be explained.

To put the disposable diaper on, a caregiver pulls the fastening tape in the back lower-torso region to the front lower-torso region. As the caregiver brings the fastening tape to the front lower-torso region, he or she fastens the fastening tape to the corresponding target section.

Fig. 5 is illustrates the disposable diaper according to the embodiment, when worn by a wearer. In Fig. 5, the fastening tapes have been fastened inboard in the width direction and oriented toward the crotch region, so that the disposable diaper is worn in a manner that the front lower-torso region is pulled up and outward in the width direction.

Worn in this way, the disposable diaper is facilitated to cover the plump belly of the infant because the front lower-torso region thereof is sustained upward.

Further, the back end of the disposable diaper is pulled in the width direction when the fastening tapes are pulled to the front lower-torso region while the disposable diaper is being worn. Figs. 6(a) to (c) illustrate how the back waist elastic sheet is deformed when the back lower-torso region of the disposable diaper is pulled in the width direction via the fastening tapes. Fig. 6(a) illustrates a pre-deformed state; Fig. 6(b) illustrates a state in which an outward pull in the product width direction has been applied to the state in Fig. 6(a); and Fig. 6(c) illustrates a state in which the fastening tapes have been further pulled.

When the disposable diaper is in the pre-deformed state as shown in Fig. 6(a), the back end of the disposable diaper has a curved shape in which the product widthwise center of the back end is recessed inward in the product longitudinal direction from the product widthwise outer ends. Further, when the disposable diaper is in the pre-deformed state, the front end of the back waist elastic sheet has a curved shape in which the product widthwise center of the front end is recessed outward in the product longitudinal direction from the product widthwise outer ends.

The state shown in Fig. 6(b) is brought about when the fastening tapes in the pre-deformed state are slightly pulled outward in the width direction. The back end of the disposable diaper is pulled in the width direction when the fastening tapes are pulled to the front lower-torso region. In this state, the back end of the disposable diaper still has a curved shape in which the product widthwise center of the back end is recessed inward in the product longitudinal direction from the product widthwise outer ends.

Further, the front end of the back waist elastic sheet has a curved shape in which the product widthwise center of the front end is recessed outward in the product longitudinal direction from the product widthwise outer ends.

The state shown in Fig. 6(c) is brought about when the fastening tapes in the state shown in Fig. 6(b) are slightly pulled outward in the width direction. The back end of the disposable diaper becomes substantially parallel to the product width direction.

The front end of the back waist elastic sheet has a curved shape in which the product widthwise center of the front end is recessed outward in the product longitudinal direction from the product widthwise outer ends.

Furthermore, because the back end of the disposable diaper has a curved shape in the pre-deformed state, the back end of the disposable diaper is greater in length in the width direction than portions inward in the product longitudinal direction from the back end. Hence, the back end of the disposable diaper is readily stretched in the width direction. However, when the disposable diaper is pulled outwardly in the width direction and strained, as shown in Fig. 6(c), that is, when the disposable diaper is worn by the wearer, the extension amount of the back end of the disposable diaper via the waist elastic sheet is greater than the extension amounts in portions inward in the product longitudinal direction from the back end (for example, the front end of the back waist elastic sheet) via the waist elastic sheet. Thus, biasing force of the back waist elastic sheet increases outwardly in the product longitudinal direction. When the disposable diaper is worn, the back end of the back waist elastic sheet can pull the front lower-torso region upward and outward in the width direction. (2) Manufacturing method for disposable diaper

The following will explain one example of a manufacturing method for the disposable diaper according to the embodiment. Note that, for methods that will not be explained in the embodiment, any existing method(s) may be used. Further, the manufacturing method to be explained below is merely an example, and other manufacturing method(s) may also be employed. The manufacturing method for the disposable diaper at least includes a component forming step, a component arranging step, leg-area forming step, and a cutting step.

In the manufacturing method for the disposable diaper, individual disposable diapers are manufactured as follows: a continuous body of a plurality of disposable diapers connected to each other in the product longitudinal direction is made, and then the continuous body is cut to the size of an individual disposable diaper along the product width direction WV.

In the component forming step, components of the disposable diaper are formed. Specifically, the absorbent 40 is formed by layering absorbent materials, for example.

In the component arranging step, components of the disposable diaper 10, such as continuous webs of waist elastic sheet and top sheet, the absorbent, the leg elastic zone 75, and secondary elastic zone 77, are arranged on top of a continuous web of back sheet.

Here, for the waist elastic sheet, the front waist elastic sheet 86 of one disposable diaper and the back waist elastic sheet 85 of the adjacent disposable diaper are not yet separated. The side ends of the waist elastic sheet, which are to be the product widthwise outer ends of the disposable diaper when the disposable diaper is formed, are held with suction means or the like, and the waist elastic sheet is stretched in a

DISPOSABLE DIAPER =F og

Specification = ’ 1

TECHNICAL FIELD . J

The present invention relates to a disposable diaper. | 4

BACKGROUND ART

Disposable diapers having a front lower-torso region, a crotch region, and a back lower-torso region, and including an absorbent extending from the crotch region to the front lower-torso region and the back lower-torso region, and a fastening tape for fastening the front lower-torso region and the back lower-torso region to each other, have been known (see, for example, Patent Literature 1).

In general, the fastening tape extends laterally outward from a lateral end of the back lower-torso region of the disposable diaper. When the disposable diaper of Patent

Literature 1 is worn, the crotch region of the disposable diaper is brought adjacent the crotch area of a wearer and in this state the fastening tape in the back lower-torso region is pulled to the front lower-torso region so that the fastening tape is fastened to the front lower-torso region.

Further, a waist opening of the disposable diaper of the Patent Literature 1 is provided with an elastic member that is elastically extensible in the width direction. The waist opening of the disposable diaper fits around the wearer's waist by way of elastic extension of the elastic member.

CITATION LIST

PATENT LITERATURE

Patent Literature 1: JP 2006-20665 A

SUMMARY OF INVENTION

Typically, infants have plump bellies. It is reasonable for a caregiver to fasten a fastening tape of a disposable diaper on the bulge of the belly of an infant in order to properly cover the belly bulge. When the fastening tape is fastened ion the belly bulge, a region laterally extending from the fastening tape closely fits the wearer's body while an the product width direction of the disposable diaper and affixed onto a continuous web.

Because the waist elastic sheet is stretched with its side ends held, the side ends of the waist elastic sheet are hardly stretched. The extensibility of the side ends of the waist elastic sheet in the product width direction will be lower than the extensibility of the area between the side ends in the product width direction.

Specifically, the region in which the waist elastic sheet of the disposable diaper is formed will have three zones having different extensibilities. The three zones in the region in which the waist elastic sheet of the disposable diaper is formed, are: a central zone located in the product widthwise center of the region, a lateral zone located at each of the product widthwise ends in the region (corresponding to the side ends of the waist elastic sheet), and an intermediate zone between the central zone and the lateral zone; and the relation of these zones in terms of extensibility is: extensibility of the central zone in the product width direction > extensibility of the intermediate zone in the product width direction > extensibility of the lateral zone in the product width direction.

The extensibility of the central zone in the product width direction can be 1.4 to 1.8. The extensibility of the lateral zone in the product width direction is set lower than the extensibility of the central zone in the product width direction, which can be 1.0 to 1.1.

The extensibility of the intermediate zone in the product width direction can be set lower than the extensibility of the central zone in the product width direction but higher than the extensibility of the lateral zone in the product width direction, which can be 1.2t0 1.3. It is noted that, the extensibility of the lateral zone in the product width direction can be 1.0 and thus this zone may not be practically stretchable.

Further, the elastic sheet that has been stretched in the product width direction is narrowed in the product longitudinal direction. In particular, the product widthwise center of the elastic sheet is narrowed. Hence, in the stretched-out elastic sheet, a length in the product longitudinal direction at the product widthwise center is shorter than that at the product widthwise end. In the elastic sheet affixed in such narrowed state, as shown in Fig. 1, product longitudinal ends of the elastic sheet, such as the back end of the front waist elastic sheet and the front end of the back waist elastic sheet, have curved shapes in which the widthwise centers thereof are recessed from the widthwise outer ends thereof,

In the leg-area forming step, the top sheet 50, the external sheet 60, and the back sheet 60a are cut. As a result, the front ends 77F of the secondary elastic zones 77 are cut, and the leg openings 35 to encircle the wearer's legs are formed.

In the cutting step, the continuous body in which the top sheet 50, the back sheet 60a, the absorbent 40, and other components have been arranged is cut in the product width direction W to the size of a product. In this way, the disposable diaper 10 is manufactured.

As the individual disposable diapers are cut from the continuous body, the waist elastic sheets and the leg elastic zones in the disposable diapers which have been stretched are relaxed, assuming the relaxed position. As the stretched state is relaxed, the waist elastic sheet that has been narrowed due to the stretching is deformed to return to the state before narrowing. Thus, the back end of the back waist elastic sheet and the front end of the front waist elastic sheet, which have been straight in the stretched state, are deformed and curved in the relaxed state.

The front end of the front waist elastic sheet contracts by a greater amount compared to the back end of the front waist elastic sheet, so that the product widthwise center of the front end of the disposable diaper is recessed inward in the product longitudinal direction from the product widthwise outer ends of the front end of the disposable diaper, creating a curved shape. Similarly, the back end of the back waist elastic sheet contracts by a greater amount compared to the front end of the back waist elastic sheet, so that the product widthwise center of the back end of the disposable diaper is recessed inward in the product longitudinal direction from the product widthwise outer ends of the back end of the disposable diaper, creating a curved shape.

Further, as the individual disposable diapers are cut from the continuous body and assume the relaxed position, the front end of the front waist elastic sheet contracts by a greater amount compared to the back end of the front waist elastic sheet, and the back end of the back waist elastic sheet contracts by a greater amount compared to the front end of the back waist elastic sheet. The greater amount of contraction of the front end of the front waist elastic sheet is attributed to the fact that the front end of the front waist elastic sheet is more spaced from the absorbent core 40a compared to the back end of the front waist elastic sheet and hence it is less affected by the stiffness of the absorbent core 40a. The greater amount of contraction of the back end of the back waist elastic sheet is attributed to the fact that the back end of the back waist elastic sheet is more spaced from the absorbent core 40a compared to the front end of the back waist elastic sheet and hence it is less affected by the stiffness of the absorbent core 40a. (3) Operation and effect

The back end of the disposable diaper can contract with ease because the back waist elastic sheet has been disposed thereat, facilitating the extending and contracting in the width direction and also because the back end of the disposable diaper assumes a curved shape in the relaxed state. When the disposable diaper is worn, the waist elastic sheet at the back end of the disposable diaper can pull the front lower-torso region upward and outward in the width direction. For example, even when the disposable diaper is displaced, it can still cover the belly bulge of the wearer because the front lower-torso region has been pulled upward and outward in the width direction.

The back waist elastic sheet overlaps the waist holding section. More preferably, the back waist elastic sheet crosses the product longitudinal center of the waist holding section, and more preferably, the back waist elastic sheet crosses a crotch-side end in the product longitudinal direction of the waist holding section. The waist holding section for holding the disposable diaper against the wearer's body can contract in the width direction via the waist contracting section; hence, even when the disposable diaper is displaced, the waist holding section can constantly fit the waist of the wearer.

The back end of the back waist elastic sheet does not overlap the absorbent,

but the front end of the back waist elastic sheet overlaps the absorbent. The absorbent, among components of the disposable diaper, has relatively high stiffness. For this reason, the area of the back waist elastic sheet overlapping the absorbent does not contract as much as the absorbent non-overlapping area thereof.

Hence, the back end of the back waist elastic sheet can relatively contract with more ease than the front end of the back waist elastic sheet, more effectively pulling the front lower-torso region upward when the disposable diaper is worn.

The low-stiffness region is disposed at the back end of the absorbent. The low-stiffness region facilitates the back end of the absorbent to deploy in the width direction, so that the back end of the waist elastic sheet can more readily stretch in the product width direction when the disposable diaper is being worn. Hence, when the disposable diaper is worn, the back waist elastic sheet can further effectively pull the front lower-torso region upward.

The front end of the disposable diaper can be positioned on the belly bulge of the wearer. Here, if the front end is parallel to the width direction, the front end would not conform to the curved shape of the wearer's budging belly. The curved shape of the front end, however, assists the front end to conform to the belly bulge of the wearer.

When the disposable diaper is in the relaxed state, the product longitudinal center of the extension is positioned outboard in the product longitudinal direction from the product longitudinal center of the base. That is, when the disposable diaper is in the relaxed state, the extension of the fastening tape does not extend parallel to the product width direction, but is inclined from inward to outward in the width direction, outwardly in the product longitudinal direction.

Because the extension of the fastening tape is outboard in the longitudinal direction from the base of the fastening tape, when the fastening tape is fastened in the front, the extension is readily positioned on the crotch side relative to the base. Thus, the fastening tape can readily exert pulling force on the back side and the upper side.

The back film is disposed inboard in the product longitudinal direction from the back end of the disposable diaper. The area in which the liquid-impermeable back sheet is disposed will have higher stiffness and thus less stretchable compared to the area in which the back sheet is not disposed.

The back end of the disposable diaper is more readily deployed in the width direction, and the back end of the waist elastic sheet is more readily stretched in the width direction when the disposable diaper is being worn, so that the front lower-torso region is more effectively pulled upward when worn. (4) Other embodiments

The content of the present invention has been disclosed as above through the embodiments of the present invention; however, the description and drawings as part of the disclosure should not be understood as limitation to the invention. After reviewing this disclosure, various alternative embodiments, examples, and practicable techniques will be apparent to those skilled in the art.

In a modification example, a back waist elastic sheet may not overlap a waist holding section.

In a modification example, a back waist elastic sheet may be disposed so that it does not overlap an absorbent but a front waist elastic sheet may be disposed so that it overlaps the absorbent.

In a modification example, a low-stiffness region may not be formed in an absorbent 40.

In a modification example, the disposable diaper may not have a front waist elastic sheet.

In a modification example, when the disposable diaper is in a relaxed state, a product longitudinal center of an extension may be aligned with a product longitudinal center of a base in the product longitudinal direction, or the product longitudinal center of the extension may be inboard in the product longitudinal direction from the product longitudinal center of the base.

In a modification example, a back film may extend to a back end of the disposable diaper, may extend to a front end of the disposable diaper; and/or may extend to the product widthwise ends of the disposable diaper.

Hence, it is obvious that the invention includes various embodiments that are not described herein. Therefore, the technical scope of the invention is defined solely by matters specifying the invention stated in the scope of the claims which are valid from the above description.

It is appreciated that Japanese Patent Application No. 2013-156030 (filed on

July 26, 2013) is incorporated herein in its entirety by reference.

INDUSTRIAL APPLICABILITY

A disposable diaper that can properly cover the bulge of the wearer's belly can be provided.

Reference Signs List 10: disposable diaper 20: front lower-torso region 25: crotch region 30: back lower-torso region 35: leg opening 40: absorbent 40a: absorbent core 40b: core wrap 50: top sheet 60: external sheet 60a: back sheet 70: side flap 75: leg elastic zone 75F: front end 75R: back end 77: secondary elastic zone

77F: frontend 77R: back end 80: leg side gathers 81: elastic member 85: back waist elastic sheet 85F: front end 85R: back end 86: front waist elastic sheet 86F: front end 86R: back end 90: fastening tape 91: substrate sheet 92: hook sheet 93: base 94: extension 95: target section 110: low-stiffness region

L: product longitudinal direction

W: product width direction é . elastic member in the waist opening laterally contracts so as to provide a fit around the wearer's belly.

When the fastening tape is fastened on the belly bulge, the measurement of the region of the disposable diaper laterally extending from the fastening tape is adapted to the measurement of the plump belly of the wearer. However, as the wearer moves, the disposable diaper can be displaced. For example, when the fastening position of the fastening tape of the disposable diaper is displaced to the crotch side, the region laterally extending from the fastening tape is displaced from the belly bulge of the wearer.

Consequently, the measurement of the region laterally extending from the fastening tape becomes higher than the measurement of the wearer's waist, so that the disposable diaper can be displaced even further.

The present invention addresses the above problem with an object of providing a disposable diaper that can properly cover wearer's belly bulge.

A disposable diaper (a disposable diaper 10) according to the disclosure herein includes a front lower-torso region (a front lower-torso region 20), a back lower-torso region (a back lower-torso region 30), and a crotch region (a crotch region 25) between the front lower-torso region and the back lower-torso region; a product longitudinal direction (a product longitudinal direction L) from the front lower-torso region to the back lower-torso region; a product width direction (a product width direction W) orthogonal to the product longitudinal direction; an absorbent (an absorbent 40) extending from the crotch region to at least one of the front lower-torso region and the back lower-torso region; a pair of fastening tapes (fastening tapes 90) disposed on product widthwise outer ends of the back lower-torso region and configured to be fastened to the front lower-torso region; and a waist elastic sheet extending bilaterally from the center in the product width direction of the disposable diaper and being elastically extensible in the product width direction. The waist elastic sheet includes a back waist elastic sheet (a back waist elastic sheet 85) disposed at a back end of the disposable diaper, and when the disposable diaper is in a relaxed state, the back end of the disposable diaper has a curved shape in which the product widthwise center is recessed inward in the product longitudinal direction from the product widthwise outer ends.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a flat-out, plan view of a disposable diaper according to the embodiment, in a stretched state.

Fig. 2 is a plan view of a portion of the disposable diaper according to the embodiment, in a relaxed state.

Fig. 3 is a cross-sectional view of the disposable diaper taken along the line

F1-F1 shown in Fig. 1.

Fig. 4 is a cross-sectional view of the disposable diaper taken along the line

F2-F2 shown in Fig. 1.

Fig. 5 is a view illustrating the disposable diaper according to the embodiment, when worn by a wearer.

Figs. 6(a) to 6(c) are schematic views of deformed states of a back waist elastic sheet.

DESCRIPTION OF EMBODIMENTS

Embodiments of a disposable diaper 10 of the invention will now be described with reference to the drawings. Note that, in the following description of the drawings, the same or like parts are given the same or like reference sign. Note also that the drawings are for schematic depiction only and that dimensional ratios are different from those in a real-world setting.

Thus, specific dimensions or the like should be determined taking the following explanation into consideration. Note also that, some dimensional relations or ratios may be different between the drawings. (1) Overall schematic configuration of disposable diaper

Fig. 1 is a flat-out, plan view of a disposable diaper 10 according to the embodiment, in a stretched state. Fig. 2 is a plan view of a portion (back end portion) of the disposable diaper according to the embodiment, in a relaxed state. Fig. 3 is a cross-sectional view of the disposable diaper taken along the line F1-F1 shown in Fig. 1.

Fig. 4 is a cross-sectional view of the disposable diaper taken along the line F2-F2 shown in Fig. 1.

The stretched state shown in Fig. 1 illustrates a state in which a leg elastic zone 75 and an elastic member 81 of leg side gathers 80 have been stretched to such extent that no wrinkles are formed in components of the disposable diaper, for example, a top sheet 50 and a side flap 70. A relaxed state, as opposed to the stretched state, is a state in which the disposable diaper 10 has been taken out from a package if it had been enclosed therein and kept in an atmosphere at a temperature of 20°C + 2°C and a relative humidity (RH) of 60% + 5% for 12 hours. The disposable diaper in the relaxed state has wrinkles in its components, for example, the top sheet 50 and the side flap 70.

The disposable diaper 10 is a disposable diaper of a tape type. Here, a tape-type diaper is one whose laterally outer end of the front lower-torso region and laterally outer end of the back lower-torso region are not joined prior to use but are joined via a fastening member such as a fastening tape when the diaper is worn.

The disposable diaper 10 has a front lower-torso region 20, a crotch region 25, and a back lower-torso region 30. The front lower-torso region 20 is the area that will come in contact with the front lower torso (i.e., the belly) of the wearer. The back lower-torso region 30 is the area that will come in contact with the back lower torso (i.e. the back) of the wearer. The crotch region 25 is located between the front lower-torso region 20 and the back lower-torso region 30.

Note that, in the embodiment, a direction from the front lower-torso region 20 to the back lower-torso region 30 is referred to as a product longitudinal direction L, and a direction that is orthogonal to the product longitudinal direction L is referred to as a product width direction W.

The disposable diaper 10 includes an absorbent 40 extending from the crotch region 25 to at least one of the front lower-torso region 20 and the back lower-torso region 30. The absorbent 40 is formed by an absorbent core 40a and a core wrap 40b.

The absorbent core 40a may be similar to that of any conventional disposable diapers, and can be suitably formed of well-known members and materials, for example, comminuted pulp and super absorbent polymer. The absorbent core 40a is wrapped by the core wrap 40b in the form of sheet.

The core wrap 40b is a sheet that covers the absorbent core 40a. At least a portion of a skin-facing surface of the core wrap 40b is formed by a liquid-permeable nonwoven fabric made of various kinds of filament or a tissue sheet. For example, an air-through filament nonwoven fabric, spunbond nonwoven fabric, SMS (spunbond-meltblown-spunbond) nonwoven fabric having a mass of about 10 to 30 g/m? or atissue sheet having a mass of about 10 to 30 g/m? can be used.

A low-stiffness region 110 is disposed as a low-stiffness area in the absorbent 40 in the back lower-torso region, which has a basis weight lower than other areas of the absorbent or in which the absorbent core 40a is absent. The low-stiffness region 110 has a shape in which a product widthwise length gradually decreases from the product widthwise center of an end of the absorbent 40 in the back lower-torso region toward the front lower-torso region. More specifically, the low-stiffness region has a wedged shape in plan view of the disposable diaper. A border line between the absorbent core 40a and the low-stiffness region 110 has an arc shape protruding toward the product widthwise (W) center. The absorbent 40 outboard in the product width direction from the low-stiffness region 110 each has a trapezoidal shape narrowing toward the end of the absorbent 40 in the back lower-torso region.

The liquid-permeable top sheet 50 is disposed on a top surface (i.e., skin-facing surface) of the absorbent 40. Further, a liquid-impermeable back sheet 60a is disposed on a bottom surface (i.e., non-skin-facing surface) of the absorbent 40. An external sheet 60 is disposed on a bottom surface (i.e., non-skin-facing surface) of the back sheet 60a.

The back sheet 60a is disposed inward in the product longitudinal direction from a front end 10F of the disposable diaper, and inward in the product longitudinal direction

DE eeeeeTTETET—T—TETETETETEEEELESSSSSSSSSSSSSS ee from a back end 10R of the disposable diaper. The back sheet 60a is disposed inboard in the product width direction from the product widthwise ends of the disposable diaper.

The external sheet is disposed as a non-skin-contacting surface of the disposable diaper.

The external sheet is formed by, for example, a nonwoven fabric.

A side flap 70 is disposed on each product widthwise (W), side margin of the absorbent 40. The side flap 70 is disposed from the front lower-torso region 20 through the crotch region 25 to the back lower-torso region 30, and is disposed outboard in the product width direction from the absorbent 40. The side flap 70 is formed by one or more laminated nonwoven fabrics.

A pair of leg openings 35 is respectively formed in the side flaps 70 of the disposable diaper 10. The leg openings 35 are disposed on the respective product-widthwise side ends of the disposable diaper which are the areas that will encircle the legs of the wearer when the disposable diaper is worn by the wearer. The leg openings 35 are concave toward the product widthwise center of the absorbent body.

Further, the pair of side flaps 70 is individually provided with fastening tapes 90.

Each fastening tape 90 is disposed at the product widthwise outer end of the back lower-torso region, and is configured to be fastened to the front lower-torso region. The fastening tape 90 extends outward in the product width direction from the side flap 70.

In the back lower-torso region 30, the fastening tape extends in the product width direction W to be fastened to a non-skin-facing surface of the front lower-torso region 20 and thus holds the disposable diaper 10 against the wearer's body.

Target sections 95 are disposed on the non-skin-facing surface of the front lower-torso region so that the pair of fastening tapes 90 is fastened thereonto, respectively.

In the embodiment, the front lower-torso region 20, the back lower-torso region 30, and the fastening tapes 90 form a waist holding section. The waist holding section in the back lower-torso region 30 extends in the product width direction from where an engagement area of the fastening tape 90 is disposed. The waist holding section in the

CT front lower-torso region 20 extends in the product width direction from where the target section 95 is disposed.

A pair of leg elastic zones 75 are respectively disposed in the side flaps 70, where leg elastic zones are disposed inboard in the product width direction from the respective leg openings 35 and outboard in the product width direction from the absorbent 40, and are extensible in the product longitudinal direction L.

The leg elastic zones 75 may have any configuration as long as they are capable of extending and contracting the leg openings 35 in the product longitudinal direction; for example, the leg elastic zones 75 may be disposed along the respective leg openings 35, or part of the leg elastic zones 75 may be angled relative to the respective leg openings 35.

Further, a pair of secondary elastic zones 77 are disposed outboard in the product width direction from the respective leg elastic zones 75, straddling the border between the crotch region 25 and the back lower-torso region 30, and extensible in the product longitudinal direction. As the region in the side flap 70 in which the secondary elastic zone 77 has been formed contracts, the side flap 70 is enabled to conform to the buldging contour of the wearer's buttocks, covering the buttocks with the region.

As used herein, the leg elastic zone 75 and the secondary elastic zone 77 are areas that actually contract in the product longitudinal direction by means of elastic members such as rubber threads, but do not include areas in which elastic members are disposed under non-elasticized conditions.

Each leg elastic zone 75 is formed by three elastic members that are extensible in the product longitudinal direction. Each secondary elastic zone 77 is formed by a single elastic member that is extensible in the product longitudinal direction. The elastic members according to the embodiment are made of elastic polyurethane filaments and/or natural rubber.

A back end 75R of the leg elastic zone 75 is disposed in the front relative to the fastening tape 90 and inboard in the product width direction from the fastening tape.

OOS

Hence, the region that is in the front relative to the fastening tape 90 and inboard in the width direction from the fastening tape 90 will be contracted by the leg elastic zone 75.

Afront end 77F of the secondary elastic zone 77 is disposed in the back relative to a front end 75F of the leg elastic zone 75. Hence, the region in the back relative to the front end 75F of the leg elastic zone 75 will be contracted by the secondary elastic zone 77. A back end 77R of the secondary elastic zone 77 is disposed in the back relative to the back end of the leg elastic zone. Hence, the region in the back relative to the leg elastic zone 75 will be contracted by the secondary elastic zone 77.

The leg elastic zone 75 can pull up the crotch region of the disposable diaper toward the wearer's crotch area. Further, the pulling force by the leg elastic zone can be transferred to the fastening tape 90 via the secondary elastic zone 77, Hence, when the fastening tape 90 is fastened, the region between the fastening tape 90 and the leg elastic zone 75, as well as the region held against the wearer's waist by the fastening tape 90 and the region in which the leg elastic zone 75 is disposed, readily provides a close fit.

Furthermore, the region outboard in the product width direction from the leg elastic zone can be contracted by the secondary elastic zone, so that the side flap in the back lower-torso region can properly cover the wearer's buttocks. In this way, especially a back portion of the leg opening is protected from being inside-out when worn.

Furthermore, the contracting of the leg elastic zone can pull the leg opening toward the wearer's body, preventing displacement of the leg opening.

The leg elastic zone 75 is interposed between the side flap 70 and the external sheet 60. Alternatively, in the region in which the back sheet 60a is interposed between the absorbent 40 and the external sheet 60, the leg elastic zone 75 is interposed between the back sheet 60a and the side flap 70.

The extensibility of the leg elastic zone 75 is preferably 1.7 to 2.4. In the embodiment, the extensibility of the leg elastic zone 75 is set to 1.9t0 2.2. It is noted that, the extensibility is a degree of extension of the leg elastic zone and is defined as

Claims

= 3 a CLAIMS c 3 5

1. Adisposable diaper comprising: = : 2 a front lower-torso region, a back lower-torso region, and a crotch igh between the front lower-torso region and the back lower-torso region; = a product longitudinal direction from the front lower-torsa region to the & back lower-torso region; a product width direction orthogonal to the product longitudinal direction; an absorbent extending from the crotch region to at least one of the front lower-torso region and the back lower-torso region; a pair of fastening tapes disposed on product widthwise outer ends of the back lower-torso region and configured to be fastened to the front lower-torso region; and a waist elastic sheet extending bilaterally from the center in the product width direction of the disposable diaper and being elastically extensible in the product width direction, wherein the waist elastic sheet includes a back waist elastic sheet disposed at a back end of the disposable diaper, and when the disposable diaper is in a relaxed state, the back end of the disposable diaper has a curved shape in which the product widthwise center is recessed inward in the product longitudinal direction from the product widthwise outer ends when the back waist elastic sheet is stretched in product width direction, the back waist elastic sheet is narrowed in a product longitudinal direction, when the back waist elastic sheet is stretched in product width direction, a length of the back waist elastic sheet in the product longitudinal direction at the product widthwise center of the back waist elastic sheet is shorter than a length of the back waist elastic sheet in the product longitudinal direction at the product widthwise end of the back waist elastic sheet, and when the back waist elastic sheet is stretched in product width direction, a front end of back waist elastic sheet has a shape in which the product widthwise center of the front end is recessed outward in the product longitudinal direction from the product widthwise outer ends of the front end.

2. The disposable diaper according to claim 1, comprising a waist holding section in the front lower-torso region and the back lower-torso region, extending along the product width direction for holding the disposable diaper against the wearer's body, wherein the back waist elastic sheet overlaps the waist holding section.

3. The disposable diaper according to claim 1 or claim 2, wherein the absorbent is located inboard in the product longitudinal direction from a back end of the back lower-torso region, and a front end of the back waist elastic sheet overlaps the absorbent.

4. The disposable diaper according to claim 1 or claim 2, wherein a low-stiffness region is disposed in the absorbent, having a basis weight lower than other areas of the absorbent or not having the absorbent core therein, wherein the low-stiffness region has a shape in which a product widthwise length gradually decreases from a product widthwise center of a back end of the absorbent toward the front lower-torso region.

5. The disposable diaper according to claim 1 or claim 2, wherein the waist elastic sheet includes a front waist elastic sheet disposed at a front end of the disposable diaper, and when the disposable diaper is in the relaxed state, the front end of the disposable diaper has a curved shape in which the product widthwise center is recessed inward in the product longitudinal direction from the product widthwise outer ends.

6. The disposable diaper according to claim 1 or claim 2, comprising an external sheet at least in the back lower-torso region, the external sheet being disposed on a non-skin-facing side of the absorbent, the fastening tape includes a base that overlaps the external sheet and an extension that extends outward in the product width direction from the external sheet, wherein when the disposable diaper is in the relaxed state, a product longitudinal center of the extension is outboard in the product longitudinal direction from a product longitudinal center of the base.

7. The disposable diaper according to claim 1 or claim 2, comprising a liquid-impermeable back film at least in the back lower-torso region, the back film being disposed on the non-skin-facing side of the absorbent, wherein the back film is disposed inboard in the product longitudinal direction from the back end of the back lower-torso region.

8. The disposable diaper according to claim 1 or claim 2, comprising: a central zone located in the product widthwise center of a region in which the waist elastic sheet is formed, a lateral zone located at each of the product widthwise ends in the region; and an intermediate zone between the central zone and the lateral zone, wherein extensibility of the central zone in the product width direction is higher than extensibility of the intermediate zone in the product width direction, and extensibility of the intermediate zone in the product width direction is higher than extensibility of the lateral zone in the product width direction.