WO2013005423A1

WO2013005423A1 - Disposable wearing article

Info

Publication number: WO2013005423A1
Application number: PCT/JP2012/004312
Authority: WO
Inventors: Toshiyasu Yoshioka; Keiko Ichihara
Original assignee: Unicharm Corporation
Priority date: 2011-07-04
Filing date: 2012-07-03
Publication date: 2013-01-10
Also published as: AR087050A1; TW201315450A; JP5999878B2; JP2013013580A; TWM526371U

Abstract

Provided is a disposable wearing article adapted to keep the peripheries of the respective leg-openings in close contact with the wearer's body with a good fit to prevent the absorbent core from being displaced and to prevent bodily fluids from leaking out sideways. Side flaps (61) of an absorbent chassis (12) are provided with a plurality of leg elastics (62) extending in a longitudinal direction (Y). Crossover regions (70) of the respective side flaps (61) are formed with fixed sub-regions (75) secured to an elasticized waist panel (11) and free sub-regions (76) lying outboard of the fixed sub-regions (75) in a transverse direction (X) and not secured to the elasticized waist panel (11). Each of spacing dimensions (R1, R2) in the transverse direction (X) between the adjacent leg elastics (62) is in a range of about 3.0 to about 10.0mm, a spacing dimension (R2) in the transverse direction between each of the opposite side edges (45c) of the absorbent core (45) and the innermost one of the leg elastics (62) is in a range of about 3.0 to about 10.0mm. Spaced regions (69, 71) in the transverse direction (X) between the adjacent leg elastics (62) arranged in the side flaps (61) are formed with transverse wrinkles (68) at a rate of 9 to 20 wrinkles/50mm.

Description

DISPOSABLE WEARING ARTICLE

The present disclosure relates to disposable wearing articles and, more specifically, to disposable wearing articles such as disposable diapers, disposable toilet-training pants, disposable incontinent pants and disposable sanitary pants having opposite side flaps provided with a plurality of leg elastics.

Background

Disposable wearing articles that include leg elastics disposed along the peripheries of the respective leg-openings are known. For example, JP 2002-102278 A (PTL 1) discloses a disposable wearing article having a chassis defining a surface configuration of the wearing article, an absorbent core sandwiched between inner and outer sheets forming the chassis and curved leg elastics extending across a crotch region into front and rear waist regions. JP 2006-525858 A (PTL 2) discloses a wearing article having an elasticized waist panel and an absorbent chassis attached to the elasticized waist panel wherein the absorbent chassis is provided with leg elastics rectilinearly extending in a longitudinal direction along peripheries of respective leg-openings.

JP 2002-102278 A JP 2006-525858 A

In the wearing article disclosed in PTL 1, not only the peripheries of the respective leg-openings but also portions of the front and rear waist regions may be put in contact with the wearer's body with a good fit under tensile stress of the leg elastics extending across the crotch region into the front and rear waist regions. In the wearing article disclosed in PTL 2, the front and rear waist regions fit about the wearer's waist as the elasticized waist panel is stretched circumferentially about the wearer's waist and the peripheries of the respective leg-openings fit about the wearer's thighs as the absorbent chassis is stretched in the longitudinal direction of the wearing article.

However, in the wearing article disclosed in PTL 1, due to the arrangement that the absorbent core is fixed within the absorbent chassis and the front and rear waist regions have no elasticity except the periphery of the waist-opening, when the absorbent core has been displaced downward due to absorption of bodily fluids, it is impossible to pull the absorbent core upward to its initial position and, in consequence, the peripheries of the respective leg-openings are spaced apart from the wearer's inguinal regions and eventually bodily fluids might leak out sideways.

In the wearing article disclosed in PTL 2, with the wearing article put on the wearer's body, the waist elastics of the elasticized waist panel is circumferentially stretched about the wearer's waist and the leg elastics attached to the side flaps of the elastic chassis so as to intersect with the waist elastics are also stretched. In this way, the absorbent chassis should not be significantly displaced downward even after the absorbent core has absorbed bodily fluids. However, the leg elastics are rectilinearly arranged and therefore it is impossible to make the peripheries of the respective leg-openings defined by the side flaps fit to the curved thighs and the inguinal regions of the wearer. As a result, the side flaps might be squeezed in the wearer's inguinal regions and be deformed, and eventually bodily fluids might leak sideways and/or the absorbent chassis might be displaced.

There is provided a disposable wearing article having a longitudinal direction and a transverse direction being orthogonal to each other and including a skin-facing side, a non-skin-facing side, a front waist region, a rear waist region, a crotch region extending between the front and rear waist regions, an annular elasticized waist panel and an absorbent chassis attached to the elasticized waist panel.

According to the present invention:
the absorbent chassis includes an absorbent core and side flaps lying outboard of opposite side edges of the absorbent core in the transverse direction and extending in the longitudinal direction;
the side flaps are provided with a plurality of leg elastics extending in the longitudinal direction;
the leg elastics are secured to the side flaps with hot melt adhesives applied to these leg elastics;
respective regions of the side flaps intersecting with the elasticized waist panel are formed with fixed sub-regions secured to the elasticized waist panel and free sub-regions lying outboard of the respective fixed sub-regions in the transverse direction and not secured to the elasticized waist panel; and
a spacing dimension in the transverse direction between the adjacent leg elastics is in a range of about 3.0 to about 10.0mm, a spacing dimension in the transverse direction between each of the opposite side edges of the absorbent core and the innermost one of the leg elastics is in a range of about 3.0 to about 10.0mm and spaced regions in the transverse direction between the adjacent leg elastics arranged in the side flaps are formed with transverse wrinkles at a rate of 9 to 20 wrinkles/50mm.

Fig. 1 is a perspective view exemplarily showing a disposable diaper as one example of disposable wearing articles according to a first embodiment of this invention. Fig. 2 is a partially cutaway developed plan view showing the diaper developed in a front-back direction after opposite side seams have been peeled off, as viewed from the inner side. Fig. 3 is a plan view similar to Fig. 2 with the absorbent chassis removed. Fig. 4 is a schematic sectional view taken along line IV-IV in Fig. 2. Fig. 5 is a schematic sectional view taken along line V-V in Fig. 2. Fig. 6 is a scale-enlarged diagram illustrating a region surrounded by circle VI in Fig. 5. Fig. 7 is a scale-enlarged diagram illustrating a region surrounded by circle VII in Fig. 1.

Referring to Figs. 1 and 2, a diaper 10 has a longitudinal direction Y and a transverse direction X being orthogonal to each other, and includes a skin-facing side and a non-skin-facing side opposite to each other, an annular elasticized waist panel 11 circumferentially extending about the wearer's waist, an absorbent chassis 12 attached to the skin-facing side of the elasticized waist panel 11, a front waist region 13, a rear waist region 14 and a crotch region 15 extending between the front and

rear waist regions

13, 14.

The elasticized waist panel 11 functions as an elastic belt and includes a front waist panel 16 defining the front waist region 13 and a rear waist panel 17 defining the rear waist region 14. The front waist panel 16 has a transversely long rectangular shape contoured by an inner end 16a, an outer end 16b and both

side edges

16c, 16d connecting the inner and

outer ends

16a, 16b to each other. The rear waist panel 17 has a transversely long rectangular shape which is substantially the same as the front waist panel 16, and is contoured by an inner end 17a, an outer end 17b and both

side edges

17c, 17d connecting the inner and

outer ends

17a, 17b to each other. Both

side edges

16c, 16d of the front waist panel 16 and both

side edges

17c, 17d of the rear waist panel 17 which are opposed to each other, respectively, have inner surfaces thereof joined to each other, respectively, at seams 20 defined by a series of joining portions, by means of known means, for example, various kinds of heat sealing techniques such as heat embossing, ultrasonic sealing and, thereupon, a waist-opening 21 and a pair of leg-openings 22 are defined.

Each of the front and

rear waist panels

16, 17 includes an inner sheet 23 lying on the skin-facing side, an outer sheet 24 lying on the non-skin-facing side and front and

rear waist elastics

25, 26 disposed between the inner and

outer sheets

23, 24.

As the inner and

outer sheets

23, 24, at least one of liquid-impermeable SMS (spun bonded/melt blown/spun bonded) fibrous nonwoven fabrics, spun bonded nonwoven fabrics, air-through nonwoven fabrics, plastic sheets and laminates thereof may be used. The inner and

outer sheets

23, 24 are joined to each other with hot melt adhesives applied to the inner surface of at least one of these two sheets or by means of the aforementioned heat sealing techniques.

Referring to Fig. 2, a plurality of string- or strand-like front waist elastics 25 are disposed between the inner and

outer sheets

23, 24 of the front waist panel 16 to be contractible in the transverse direction X. In this way, the front waist panel 16 is elasticized at least in the transverse direction X.

The front waist elastics 25 include: a plurality of first elastics 31 extending in the transverse direction X along the outer end 16b; a plurality of second elastics 32 lying below the first elastics 31 and extending in parallel to the first elastics 31; a plurality of third elastics 33 lying below the second elastics 32 and extending in parallel to the second elastics 32; and a plurality of fourth elastics 34 lying below the third elastics 33 and extending in the transverse direction X in parallel to the third elastics 33 along the inner end 16a. The first elastics 31 define a front waist band. The fourth elastics 34 intersect with leg elastics 62 to be described later.

Specifically, as the first elastics 31, elastic material having a fineness in a range of about 400 to about 1200dtex and a stretch ratio in a range of about 2.0 to about 2.6 may be used, as the second elastics 32, elastic material having a fineness in a range of about 350 to about 1200dtex and a stretch ratio in a range of about 1.8 to about 2.6 may be used and as the third and

fourth elastics

33, 34, elastic material having a fineness in a range of about 300 to about 950dtex and a stretch ratio in a range of about 2.6 to about 3.6 may be used.

Between the inner and

outer sheets

23, 24 of the rear waist panel 17, a plurality of string- or strand-like rear waist elastics 26 are disposed to be stretchable and contractible in the transverse direction X. The rear waist panel elastics 26 make the rear waist panel 17 elastic at least in the transverse direction X.

The rear waist elastics 26 include a plurality of fifth elastics 35 extending in the transverse direction X along the outer end 16b, a plurality of sixth elastics 36 lying below the fifth elastics 35 and extending in parallel to the fifth elastics 35, a plurality of seventh elastics 37 lying below the sixth elastics 36 and extending in parallel to the sixth elastics 36 and a plurality of eighth elastics 38 lying below the seventh elastics 37 and extending in the transverse direction X in parallel to the seventh elastics 37 along the inner end 17a. The fifth elastics 35 define a rear waist band. The eighth elastics 38 intersect with leg elastics 62 to be described later.

Specifically, as the fifth elastics 35, elastic material having a fineness in a range of about 350 to about 1200dtex and a stretch ratio in a range of about 1.8 to about 2.6 may be used, as the sixth elastics 36, elastic material having a fineness in a range of about 300 to about 900dtex and a stretch ratio in a range of about 2.6 to about 3.6 may be used and as the seventh and

eighth elastics

37, 38, elastic material having a fineness in a range of about 440 to about 500dtex and a stretch ratio in a range of about 3.2 to about 3.6 may be used.

Referring to Fig. 3, in the front waist region 13, a front upper waist elastic region 40A is defined in a region in which the first and

second elastics

31, 32 have been arranged, and a pair of front lower waist elastic regions 40B is defined in a region in which the third and

fourth elastics

33, 34 have been arranged. In the rear waist region 14, a rear upper waist elastic region 41A is defined in a region in which the fifth and

sixth elastics

35, 36 have been arranged, and a pair of rear lower waist elastic regions 41B is defined in a region in which the seventh and

eighth elastics

37, 38 have been arranged.

In the front waist region 13, respective midsections of the third and

fourth elastics

33, 34 having been under tension between the pair of the front lower waist elastic regions 40B are cut or cut out to define a front inelastic region 42 in which the third and

fourth elastics

33, 34 are no longer present. In the similar fashion, in the rear waist region 14 also, respective midsections of the seventh and

eighth elastics

37, 38 having been under tension between the pair of the rear lower waist elastic regions 41B are cut or cut out to define a rear inelastic region 43 in which the elastics are no longer present. In this regard, the front inelastic region 42 may be defined by cutting the third and

fourth elastics

33, 34 at the respective midsections thereof and making them snap back. In the similar fashion, the rear inelastic region 43 may be defined by cutting the seventh and

eighth elastics

37, 38 at the respective midsections thereof.

The front and rear

inelastic regions

42, 43 formed in the front and

rear waist regions

13, 14, respectively, serve to prevent a substantially central region of the absorbent chassis 12 opposed to these

regions

42, 43 from being subjected to the contractile force of the elastics. Consequently, the absorbent core 45 included in the absorbent chassis 12 in this central region should not be creased and/or deformed under the contractile force of these elastics. In this way, the absorbent core 45 can be stably kept in contact with the wearer's body without any deteriorating its liquid-absorptive property.

A dimension in the longitudinal direction Y of the front inelastic region 42 is substantially equal to a dimension in the longitudinal direction Y of the rear inelastic region 43. However, a dimension W1 in the transverse direction X of the front inelastic region 42 is in a range of about 55 to about 90mm and a dimension W2 in the transverse direction X of the rear inelastic region 43 is in a range of about 80 to about 115mm. In this manner, the latter is larger than the former.

Referring to Figs. 2 and 5, the absorbent chassis 12 has a longitudinally long rectangular shape contoured by front and

rear ends

12e, 12f and

opposite side edges

12g, 12h and includes a front end segment 12A attached to the inner surface of the front waist panel 16, a rear end segment 12B attached to the inner surface of the rear waist panel 17 and an intermediate segment 12C extending in the longitudinal direction Y between the front and rear ends 12a, 12b.

Referring to Fig. 3, the elasticized waist panel 11 and the front and

rear segments

12A, 12B of the absorbent chassis 12 are bonded together by means of front and

rear bond regions

50, 51 formed on the surfaces of them opposed to each other. The front and

rear bond regions

50, 51 respectively include a plurality of bond lines 52 extending in the longitudinal direction Y each of which is formed of applied hot melt adhesives. A dimension in the transverse direction X (width dimension) of the respective bond lines 52 is in a range of about 3.0 to about 10.0mm and the

outermost bond lines

52a, 52b in the transverse direction X lie in the vicinity of opposite side edges of an absorbent core 45 to be described later on. In this regard, the configuration of these front and

rear bond regions

50, 51 are not limited to a plurality of lines and may be provided in the other various patterns such as Greek-capital-Omega-like-, spiral- and wavy-patterns, etc.

The absorbent chassis 12 includes a liquid-permeable inner sheet 53 lying on the skin-facing side, a hydrophobic cover sheet 54 lying on the non-skin-facing side and the absorbent core 45 interposed between the inner sheet 53 and the cover sheet 54. The absorbent core 45 has a panel geometry with its midsection in the longitudinal direction Y being concave inwardly and is entirely wrapped with a liquid-dispersant tissue paper or the like (not shown). A leakage-barrier sheet 57 formed of a liquid-impermeable plastic film is interposed between the lower surface of the absorbent core 45 and the cover sheet 54.

The absorbent core 45 is formed of a mixture of fluff wood pulp, superabsorbent polymer particles (SAP) and, optionally, heat-sealable staple fibers. According to this embodiment, side flaps 61 can be stably kept in contact with the wearer's body without bending or deforming the side flaps 61 during use of the diaper and, even when the absorbent core 45 is relatively thin, the absorbent core 45 also should not be bent or deformed during use of the diaper. In this way, it is possible to set a mass per unit area of fluff wood pulp lower than the usually adopted level. Specifically, the mass per unit area of fluff wood pulp may be set to be in a range of about 150 to about 250g/m².

As the cover sheet 54, at least one of hydrophobic SMS (spun bonded/melt blown/spun bonded) fibrous nonwoven fabrics having a mass per unit area in a range of about 10 to about 30g/m², spun bonded nonwoven fabrics and/or plastic sheets having a mass per unit area in a range of about 15 to about 30g/m² and laminates thereof may be used.

The cover sheet 54 extends outward beyond a peripheral edge of the absorbent core 45 and the extension thereof to define a pair of end flaps 60 outboard of the opposite ends of the absorbent core 45 so as to extend in the transverse direction X and a pair of the side flaps 61 outboard of the opposite side edges of the absorbent core 45 so as to extend in the longitudinal direction Y. The side flaps 61 are respectively provided with a plurality of string- or strand-like leg elastics 62 attached thereto to be contractible in the longitudinal direction Y. In this manner, the side flaps 61 and the leg elastics 62 function as gasket-cuffs adapted to be kept in close contact about the wearer's legs.

The respective leg elastics 62 include innermost leg elastics 62a closest to the opposite side edges of the absorbent core 45, outermost leg elastics 62b extending along the opposite side edges of the respective side flaps 61 and middle leg elastics 62c lying between the inner- and

outermost leg elastics

62a, 62b.

Opposite lateral segments of the cover sheet 54 defining the side flaps 61 are partially folded inward above the absorbent chassis 12 and form a pair of sleeves 64 extending in the longitudinal direction Y. Within the respective sleeves 64, a plurality of string- or strand-like cuff elastics 65 are attached with hot melt adhesives to be contractible in the longitudinal direction Y. The sleeves 64 are secured to the skin-facing side of the leakage-barrier sheet 57 by means of fixing regions 66 formed of applied hot melt adhesives and cooperate with the cuff-elastics 65 to define leakage-barrier cuffs.

As the leg elastics 62 and the cuff-elastics 65, the elastic members formed of natural rubber or synthetic rubber having a fineness in a range of about 300 to about 950dtex and a stretch ratio in a range of about 2.2 to about 3.2 may be preferably used. While the leg elastics 62 are formed of three elastic members and the cuff-elastics 65 are formed of two elastic members in this embodiment, the number of these elastic members may be more than three and more than two, respectively. The term "stretch ratio" herein used is based on a value of 1.0 representing a non-stretched state of the respective elastic members and, for example, when the elastic material having a length of 100mm in a non-stretched state is stretched to 200mm, this is the state of this elastic member having been stretched at a stretch ratio of 2.0.

The leg elastics 62 are disposed between the cover sheet 54 and the leakage-barrier sheet 57 by means of hot melt adhesive applied continuously or intermittently in the length direction of the leg elastics 62. In this regard, it is also possible to fix the leg elastics 62 between the cover sheet 54 and the leakage-barrier sheet 57 with hot melt adhesives applied to at least one of the opposed surfaces of the cover sheet 54 and the leakage-barrier sheet 57 continuously or intermittently in the length direction of the leg elastics 62 so long as the advantageous effects of this invention to be described later is achieved. When the leg elastics 62 are continuously or intermittently coated with hot melt adhesives and when the two

sheets

54, 57 are continuously or intermittently coated with hot melt adhesives, the adjacent coated regions are preferably spaced from each other by about 5.0mm or less. In this case, a desired number of transverse wrinkles 68, more specifically, nine or more transverse wrinkles 68 per a dimension of 50mm in the longitudinal direction Y of the respective side flaps 61 may be formed. In order that a required number of the transverse wrinkles 68 may be surely formed, the leg elastics 62 are continuously coated with hot melt adhesives in the length direction of the leg elastics 62. As the method of applying hot melt adhesives, various methods of known art may be used. For example, for intermittent application, various types of spraying application methods may be used and, for continuous applications, the elastic members may be transported below a nozzle ejecting molten hot melt adhesives so that substantially the entire peripheral surfaces of the elastic members may be coated with hot melt adhesives.

Referring to Figs. 6 and 7, a dimension (width dimension) in the transverse direction X of the respective side flaps 61, i.e., a spacing dimension W3 between the side edge 45c of the absorbent core 45 and the outer edge (the outer edges 12g of the absorbent chassis 12) of the side flap 61 is in a range of about 10.0 to about 35.0mm, more preferably in a range of about 12.0 to about 30.0mm. A dimension (spacing dimension) R1 in the transverse direction X of the outer spaced region 69 defined between the outermost leg elastic 62b and the middle leg elastic 62c is in a range of about 3.0 to about 10.0mm, more preferably in a range of about 4.0 to about 8.0mm, and a dimension (spacing dimension) R2 in the transverse direction X of a spaced region 70 defined between the side edge 45c of the absorbent core 45 and the innermost leg elastic 62a is in a range of about 3.0 to about 10.0mm. A dimension (spacing dimension) R3 in the transverse direction X of the inner spaced region 71 defined between the innermost leg elastic 62a and the middle leg elastic 62c is in a range of about 3.0 to about 10.0mm, more preferably in a range of about 4.0 to about 8.0mm. The respective side flaps 61 may be provided with a plurality of leg elastics 62 at relatively small intervals to form the side flaps 61 with a plurality of the transverse wrinkles 68 extending in the transverse direction. It should be noted here that the inner and outer spacing dimensions R1, R3 between the leg elastics 62 are center-to-center distances, respectively.

While the outermost leg elastics 62b are not spaced apart from the outer side edges of the associated side flaps 61 in this embodiment, the elastic members 62b may be spaced apart from the outer side edges of the associated side flaps 61 so long as the advantageous effects of this invention to be described later can be assured. In this case, the spacing dimension is preferably 4.0mm or less. This is because, if this spacing dimension exceeds 4.0mm, none of the transverse wrinkles 68 will be formed between the outermost leg elastics 62c and the outer side edges of the associated side flaps 61 and it will be impossible to obtain the effect that the side flaps 61 as a whole are formed with the transverse wrinkles 68 to have a sufficiently high stiffness to restrict an undesirable sag and deformation of the side flaps 61.

Referring to Fig. 6, the innermost leg elastics 62a lie immediately below the fixing region 66 functioning as a proximal end for the sleeve 64 so that contraction of the innermost leg elastics 62a may serve to maintain associated barrier cuffs in standing up posture and thereby to prevent the barrier cuffs from collapsing inward or outward to be spaced apart from the wearer's body.

In the front bond region 50 in which the front end segment 12A of the absorbent chassis 12 is bonded to the front waist panel 16, the outermost bond line 52a extends outward across the innermost leg elastic 62a to the middle leg elastic 62c. Specifically, crossover regions 74 of the side flaps 61 in which the leg elastics 62 are present include fixed sub-regions 75 secured to the front waist panel 16 by means of the front bond region 50 and free sub-regions 76 extending outward in the transverse direction X from the fixed sub-region 75.

Fig. 7 is a scale-enlarged diagram illustrating a region surrounded by circle VII in Fig. 1. In this regard, while a description given hereunder is limited to the side of the front waist region 13 of the diaper 10, the description is true for the side of the rear waist region 14.

Referring to Fig. 7, the respective side flaps 61 are formed with a plurality of the transverse wrinkles 68 extending in the transverse direction X under the effect of contraction of the leg elastics 62. In respective portions of the fixed region 75 and the free region 76 having a dimension L1 in the longitudinal direction Y in a range of about 15.0 to about 40.0mm, the leg elastics 62 intersect with the fourth elastics 34. The respective side flaps 61 are provided with a plurality of elastic members arranged at a relatively small interval as has previously been described and, in consequence, the respective side flaps 61 are formed with correspondingly many transverse wrinkles 68. Specifically, the transverse wrinkles 68 are formed at a relatively high density, i.e., at a rate of about 10 to about 25 wrinkles/50mm.

In this manner, the side flaps 61 are respectively formed with the fine transverse wrinkles 68 in relatively high density and the free sub-regions 76 are defined in the region 74 intersecting with the front waist panel 16 and the absorbent chassis 12. With such an arrangement, the front crotch side edges 77 of the respective side flaps 61 extending along the opposite side edges of the front crotch section should not be squeezed by the wearer's crotch and, in consequence, the function thereof to prevent bodily fluids from leaking sideways should not be deteriorated. While the front crotch side edges 77 should normally face the wearer's inguinal regions, if the side flaps 61 are poor in stiffness, the front crotch side edges 77 would be irregularly twisted or partially caught between the wearer's thighs and consequently could not properly function as gasket cuffs.

According to this embodiment, however, the front crotch side edges 77 of the respective side flaps 61 are formed in the respective outer spaced regions 69 with a plurality of relatively fine transverse wrinkles 68 so as to ensure a sufficiently high stiffness to prevent the front crotch side edges 77 from partially curling up and/or being caught between the wearer's thighs. In this way, the front crotch side edges 77 as a whole may be put in close contact with the wearer's body. In the crossover region 74, the side flaps 61 are stably secured to the front waist panel 16 in the fixed sub-regions 75 thereof including the inner spaced region 71 so that the side flaps 61 may be pulled in the transverse direction X when the front waist panel 16 is stretched in the transverse direction X. The free sub-regions 76 is free from any interference of movements of the elasticized waist panel 11 so that the front crotch side edges 77 defined along the opposite side edges of the front section of the crotch region and formed with the transverse wrinkles 68 may be kept in contact with the wearer's body.

The spaced region 70 defined between the absorbent core 45 and the innermost leg elastic 62a having substantially the same dimension as the spacing dimension between the adjacent leg elastics 62 is also formed with the transverse wrinkles 68. In consequence, this spaced region 70 also has a sufficiently high stiffness enough that the absorbent core 45 should not be twisted or deformed by being caught between the wearer's thighs.

The side flaps 61 may be put in contact with the wearer's body in a broadened state in the transverse direction X without being bent in the longitudinal direction Y and the free sub-regions 76 of the side flaps 61 are put in close contact with the vicinity of the wearer's ilium. Consequently, when the front and

rear waist regions

13, 14 are pulled up during use of the diaper, the side flaps 61 as well as the absorbent core 45 are also pulled up cooperatively therewith and thereby leakage of bodily fluids due to downward displacement of the absorbent core 45 may be restricted.

As has previously been described, the dimension W2 in the transverse direction X of the rear inelastic region 43 in the rear waist region 14 is larger than the dimension W1 in the transverse direction X of the front inelastic region 42 in the front waist region 13. Consequently, the side flaps 61 in the rear waist region 14 lie on positions outboard of the positions of the side flaps in the front waist region 13 as viewed in the transverse direction X. Stiffness of the side flaps 61 improved by the transverse wrinkles 68 cooperates with the effect of crossover between the waist elastics 25, 26 and the leg elastics 62 to put the side flaps 61 in the front waist region 13 in close contact with the relatively narrow inguinal regions of the wearer and to put the side flaps 61 in the rear waist region 14 in close contact with the relatively wide buttock of the wearer. Without changing the configuration of the absorbent chassis 12, i.e., without differentiating the width dimension of the absorbent chassis 12 between the front and

rear waist regions

13, 14, the area over which the side flaps 61 are put in close contact with the wearer's skin may be differentiated between the front and

rear waist regions

13, 14 merely by providing the front and rear

inelastic regions

42, 43. Such front and rear

inelastic regions

42, 43 may be made on the usual production line for diapers and the manufacturing process will be correspondingly simple in comparison to the case in which the configuration of the absorbent chassis 12 is made dimensionally asymmetric.

<Method for measuring the number of transverse wrinkles 68>
First, the diaper 10 was developed after the seams 20 on the opposite sides had peeled off and then the absorbent chassis 12 was pulled in the longitudinal direction Y and thereby the leg elastics 62 were stretched until the wrinkles of the side flaps 61 disappear. Then point-like marks were put on positions of the respective front crotch side edges 77 spaced by 50mm downward from the lower end of the front waist region 13 and this range extending downward from the lower end 16a of the front waist region 13 to the marked positions were used as the measurement range. The outer and inner spaced

regions

69, 71 in this measurement range were respectively provided with red center lines rectilinearly extending in the longitudinal direction Y.

After the absorbent chassis 12 in such a state were left to stand at ambient temperature (room temperature in a range of about 18 to about 22^oC, relative humidity in a range of 55 to 65%) for 24 hours, the absorbent chassis 12 was released from tension in the longitudinal direction Y and the leg elastics 62 were left to contract. After the test piece had been left for a while, the number of wrinkles formed on the red lines and extending in the transverse direction X was counted. A similar measurement was conducted on a plurality of the diapers 10 (n=10) and the number of the wrinkles 68 counted for ten test pieces was averaged to obtain the number of the transverse wrinkles 68. In this regard, the term a "wrinkle" used herein means a convexity defined between the adjacent concavities and having a width dimension of 0.5mm or more in the transverse direction X.

In the crossover region 74, a tensile stress over a predetermined width of the lower front region 40B elasticized by the third and

fourth elastics

33, 34 in the front waist panel 16 is preferably higher than a tensile stress over a predetermined width of the regions elasticized by the leg elastics 62 in the side flaps 61. Under this circumstance, the elasticity of the front waist region 13 will be able to restrict downward movements and/or deformation of the side flaps 61 and thereby to retain the outer shape of the absorbent core 45 even if, after excretion, its own mass of body waste is exerted on the absorbent chassis 12 to move this downward.

Specifically, a tensile stress of the lower front elastic region 40B at a stretch ratio of 75% is 0.72N/10mm and a tensile stress of the region of the side flaps 61 elasticized by the leg elastics 62 at a stretch ratio of 75% is 0.52N/10mm.

<Method of measuring tensile stress in respective regions>
A tensile stress over a predetermined width of the lower front elastic region 40B and a tensile stress over a predetermined width of the region of the side flaps 61 elasticized by the leg elastics 62 were measured by a method described below with use of Tensile Tester (manufactured by Shimadzu Corporation in Japan: Autograph Tester, Part Number: AG-X10plus).

First, the elasticized waist panel 11 was cut off from the diaper 10, the elasticized waist panel 11 was circumferentially stretched so as to stretch the third and

fourth elastics

33, 34, and, from the lower front elastic region 40B in this condition, a portion having a width dimension of about 10.0mm (width dimension in the transverse direction X) was cut out as a test piece 1 (including a part of the front waist panel 16 and a part of the absorbent chassis 12). A length of this test piece 1 in the transverse direction X was set as the maximum elongation length (100%). Then, the absorbent chassis 12 was removed from the diaper 10 other than the diaper 10 from which the elasticized waist panel 11 had been cut off, the sleeve 64 (inclusive of the cuff elastics 65) was removed from the side flap 61 of the removed absorbent chassis 12, thereafter the side flap 61 was stretched in the longitudinal direction Y until the wrinkles disappear and a portion having a width dimension of about 10.0mm (width dimension in the longitudinal direction Y) was cut out as a test piece 2. A length of this test piece 2 was set as the maximum elongation length (100%). The test pieces 1, 2 obtained in this manner were respectively loaded on chucks of Tensile Tester and subjected to 1-cycle tests under measurement condition as follows: movement rate: 100mm/min, inversion distance: 85% of the maximum elongation length. Specifically, values of stress at a moment the length of the respective test pieces contract to 75% of the respective maximum elongation lengths after inversion were obtained. Such a measurement was conducted at least ten times with use of a plurality of the diapers 10 and measured values were averaged to obtain the values of tensile stress (N/mm) of the test pieces 1, 2. When it is difficult to make the test pieces 1, 2 each having a width dimension of 10.0mm depending on the size of the diaper 10 as a whole, it is possible to make the test pieces having a more convenient width dimension and to convert the measurement results the values for the test pieces having the width dimension of 10.0mm.

The front waist panel 16 is formed in a region facing the midsection of the absorbent core 45 with the front inelastic region 40 and, in consequence, the absorbent core 45 may be stably kept in contact with the wearer's body without being deformed even when a thickness dimension of the absorbent core 45 is relatively thin. This means that, for example, it is possible to reduce total amount of fluff wood pulp included in the absorbent core 45 and thereby to improve flexibility of the diaper 10 as a whole. In addition, the amount of raw and processed materials may be reduced and thereby the manufacturing cost can be saved.

<Measurement of contraction percentage in side flaps>
TABLE 1 comparatively indicates a contraction percentage of the side flaps 61 in Example of this invention and Comparative Examples 1 and 2. The construction and the constituent materials are the same for Example and Comparative Examples 1 and 2 except those specifically indicated in TABLE 1 and stated later. In the description about the measurement given hereunder, the width dimension means the dimension in the transverse direction Y.

<Example>
Referring to TABLE 1, in the Example, three leg elastics 62 each having a stretch ratio of 2.7 and a fineness of about 780dtex are arranged in the respective side flaps 61 and these leg elastics 62 are secured to the sheet member with hot melt adhesives applied in slit-pattern. A width dimension W3 of the respective side flaps 61 is about 15.0mm, a width dimension R2 of the respective spaced regions 70 defined between the side edges 45c of the absorbent core 45 and the innermost leg elastics 62a is about 5.0mm and width dimensions R1, R3 of the outer and inner spaced

regions

69, 71 are about 5.0mm.
<Comparative Example 1>
In the Comparative Example 1, three leg elastics 62 each having a stretch ratio of 2.7 and a fineness of about 470dtex are arranged in the respective side flaps 61 and these leg elastics 62 are secured to the sheet member with hot melt adhesives applied in slit-pattern. The dimensions W3, R1, R2 and R3 are 27.5mm, 6.0mm, 8.5mm and 13.0mm, respectively.
<Comparative Example 2>
In the Comparative Example 2, three leg elastics 62 each having a stretch ratio of 2.5 and a fineness of about 620dtex are arranged in the respective side flaps 61 and these leg elastics 62 are secured to the sheet member with hot melt adhesives applied in slit-pattern. The dimensions W3, R1, R2 and R3 are 27.5mm, 7.0mm, 10.5mm and 10.0mm, respectively.

The diapers made under the above-mentioned conditions according to Example, Comparative Example 1 and Comparative Example 2 were put on a total of 10 persons (5 male and 5 female) and 10 minutes after these diapers had been put on 10 persons, width dimension of the side flaps 61 in the respective diapers were measured. Contraction percentages (%) of the side flaps 61 were obtained by averaging values for the respective diapers calculated by dividing the width dimension W3 (mm) of the side flaps 61 before the diapers were put on by the width dimension W3 (mm) of the side flaps 61 after the diapers had been put on.

As will be apparent from TABLE 1, the outer spaced region 69 and the inner spaced region 71 were formed with thirteen (13) transverse wrinkles 68, respectively. The outer spaced region 69 and the inner spaced region 71 were evenly formed with a plurality of fine wrinkles in this manner and, in consequence, the front crotch side edges 77 of the respective side flaps 61 maintained a planar condition as a whole. Contraction percentage of the side flaps 61 was 13%. In Comparative Example 1, the outer spaced region 69 was formed with nine (9) transverse wrinkles and the inner spaced region 71 was formed with six (6) transverse wrinkles. Contraction percentage of the side flaps 61 was 52%. In the Comparative Example 2, the outer spaced region 69 was formed with seven (7) transverse wrinkles and the inner spaced region 71 also was formed with seven (7) transverse wrinkles. Contraction percentage of the side flaps was about 39%. As observed above, the contraction percentage of the side flaps was remarkably higher in the Comparative Examples 1, 2 than in the Example. Consequentially, the side flaps 61 according to the Comparative Examples 1, 2 may not retain the planar condition and eventually may sag or deformed by being caught between the wearer's thighs during use of the diaper 10.

The inventors believe that the reason that the contraction percentages of the side flaps 61 in the Comparative Examples 1, 2 are remarkably higher than that in the Example is as follows: In Comparative Example 1, the fineness of the leg elastics is about 470dtex and the relatively wide inner spaced region 71 is formed with only six (6) transverse wrinkles 68 which are defined by relatively large convexities. In this way, the stiffness is inevitably lower than the outer spaced region 69 and the wrinkles 68 readily contract. Eventually, it is impossible for this inner spaced region 71 to retain the planar condition. In the Comparative Example 2, the stretch ratio of the leg elastics 62 is 2.5 which is lower than those of the Example and the Comparative Example 1. Eventually, the outer spaced region 69 as well as the inner spaced region 71 were formed with relatively small number of the transverse wrinkles 68.

From these measurement results and comparative verification, preferably the stretch ratio of the leg elastics 62 is in a range of about 2.6 to about 3.5, the fineness thereof is in a range of about 480 to about 1030dtex and the spaced regions R1, R3 between leg elastics 62 are formed with the transverse wrinkles 68 at a rate of 9 to 20 wrinkles/50mm in order to ensure the advantageous effects of this invention such that the side flaps 61 are formed with a plurality of fine transverse wrinkles 68 to improve the stiffness correspondingly and thereby to keep the side flaps in planar and close contact with the wearer's body without the side flaps partially curled up and/or caught between the wearer's thighs.

The constituent members of the diaper 10 are not limited to those described in the description but the other various types of material widely used in the relevant technical field may be used without limitation unless otherwise stated. The terms "first" and "second" used in the description and Claims of this invention are used merely to distinguish the similar elements, similar positions or the other similar means.

The present invention described above may be arranged in at least one or more of the following features:
(i) A disposable wearing article having a longitudinal direction and a transverse direction being orthogonal to each other, the article including:
a skin-facing side;
a non-skin-facing side;
a front waist region;
a rear waist region;
a crotch region extending between the front and rear waist regions;
an annular elasticized waist panel; and
an absorbent chassis attached to the elasticized waist panel, wherein:
the absorbent chassis comprises an absorbent core and side flaps lying outboard of opposite side edges of the absorbent core in the transverse direction and extending in the longitudinal direction;
the side flaps are provided with a plurality of leg elastics extending in the longitudinal direction;
the leg elastics are secured to the side flaps with hot melt adhesives applied to these leg elastics;
respective regions of the side flaps intersecting with the elasticized waist panel are formed with fixed sub-regions secured to the elasticized waist panel and free sub-regions lying outboard of the respective fixed sub-regions in the transverse direction and not secured to the elasticized waist panel; and
a spacing dimension in the transverse direction between the adjacent leg elastics is in a range of about 3.0 to about 10.0mm, a spacing dimension in the transverse direction between each of the opposite side edges of the absorbent core and the innermost one of the leg elastics is in a range of about 3.0 to about 10.0mm and spaced regions in the transverse direction between the adjacent leg elastics arranged in the side flaps are formed with transverse wrinkles at a rate of 9 to 20 wrinkles/50mm.

The aspect(s) of the present invention described in the above item (i) may include at least the following embodiments, which may be taken in isolation or in combination with one another:
(ii) The leg elastics are formed of elastic yarns or threads each having a stretch ratio in a range of about 2.6 to about 3.5 and a fineness in a range of about 480 to 1030 dtex.
(iii) A dimension in the transverse direction of the respective side flaps is in a range of about 10.0 to about 35.0mm.
(iv) A spaced region in the transverse direction defined between each pair of the adjacent leg elastics includes an inner spaced region defined in the fixed sub-region of the respective side flaps and an outer spaced region defined in the free sub-region of the respective side flaps.
(v) In the front and rear waist regions, elastic regions adapted to be contractible in the transverse direction under the effect of a plurality of string- or strand-like waist elastics arranged therein are defined and the waist elastics partially intersect with the leg elastics.
(vi) In the front and rear waist regions, respective midsections of the elastic regions facing the absorbent core are formed with front and rear inelastic regions and a dimension in the transverse direction of the rear inelastic region is larger than a dimension in the transverse direction of the front inelastic region.
(vii) A tensile stress over a predetermined width of sub-regions of the respective elastic regions intersecting with the crossover regions of the respective side flaps is higher than a tensile stress over a predetermined width of sub-regions provided with the leg elastics of the crossover regions.
(viii) The hot melt adhesive with which the leg elastics are secured to the side flaps is intermittently applied to the leg elastics at intervals of about 5.0mm or less in the length direction of the leg elastics.
(ix) The hot melt adhesives with which the leg elastics are secured to the side flaps are continuously applied to the leg elastics in the length direction of the leg elastics.

The described aspects and/or embodiments provide one or more of the following effects:
In the disposable wearing article according to this invention, the crossover regions of the respective side flaps intersecting with the elasticized waist panel are formed with the fixed sub-regions in which the leg elastics are arranged and the side flaps are secured to the elasticized waist panel and the free sub-regions not secured to the elasticized waist panel. The fixed sub-regions constituting the crossover regions function to allow the side flaps also to be pulled upward when the elasticized waist panel is pulled up without a possibility that the vicinity of the opposite side edges of the absorbent core might be spaced downward from the wearer's body. The free sub-regions constituting the crossover regions function to allow the peripheries of the leg-openings which are continuous with the free sub-regions to be kept in close contact with the wearer's skin without loss of a plurality of the transverse wrinkles formed under contraction of the leg elastics and thereby to prevent bodily fluids from leaking out sideways.

This application claims the benefit of Japanese Application No. 2011-148702 the entire disclosure of which is incorporated by reference herein.

Claims

A disposable wearing article having a longitudinal direction and a transverse direction being orthogonal to each other, the article comprising:
a skin-facing side;
a non-skin-facing side;
a front waist region;
a rear waist region;
a crotch region extending between the front and rear waist regions;
an annular elasticized waist panel; and
an absorbent chassis attached to the elasticized waist panel, wherein:
the absorbent chassis comprises an absorbent core and side flaps lying outboard of opposite side edges of the absorbent core in the transverse direction and extending in the longitudinal direction;
the side flaps are provided with a plurality of leg elastics extending in the longitudinal direction;
the leg elastics are secured to the side flaps with hot melt adhesives applied to these leg elastics;
respective regions of the side flaps intersecting with the elasticized waist panel are formed with fixed sub-regions secured to the elasticized waist panel and free sub-regions lying outboard of the respective fixed sub-regions in the transverse direction and not secured to the elasticized waist panel; and
a spacing dimension in the transverse direction between the adjacent leg elastics is in a range of about 3.0 to about 10.0mm, a spacing dimension in the transverse direction between each of the opposite side edges of the absorbent core and the innermost one of the leg elastics is in a range of about 3.0 to about 10.0mm and spaced regions in the transverse direction between the adjacent leg elastics arranged in the side flaps are formed with transverse wrinkles at a rate of 9 to 20 wrinkles/50mm.
The wearing article defined by claim 1, wherein the leg elastics are formed of elastic yarns or threads each having a stretch ratio in a range of about 2.6 to about 3.5 and a fineness in a range of about 480 to 1030 dtex.
The wearing article defined by claim 1, wherein a dimension in the transverse direction of the respective side flaps is in a range of about 10.0 to about 35.0mm.
The wearing article defined by claim 1, wherein a spaced region in the transverse direction defined between each pair of the adjacent leg elastics comprises an inner spaced region defined in the fixed sub-region of the respective side flaps and an outer spaced region defined in the free sub-region of the respective side flaps.
The wearing article defined by claim 1, wherein, in the front and rear waist regions, elastic regions adapted to be contractible in the transverse direction under the effect of a plurality of string- or strand-like waist elastics arranged therein are defined and the waist elastics partially intersect with the leg elastics.
The wearing article defined by claim 5, wherein, in the front and rear waist regions, respective midsections of the elastic regions facing the absorbent core are formed with front and rear inelastic regions and a dimension in the transverse direction of the rear inelastic region is larger than a dimension in the transverse direction of the front inelastic region.
The wearing article defined by claim 5, wherein a tensile stress over a predetermined width of sub-regions of the respective elastic regions intersecting with the crossover regions of the respective side flaps is higher than a tensile stress over a predetermined width of sub-regions provided with the leg elastics of the crossover regions.
The wearing article defined by claim 1, wherein the hot melt adhesives with which the leg elastics are secured to the side flaps is intermittently applied to the leg elastics at intervals of about 5.0mm or less in the length direction of the leg elastics.
The wearing article defined by claim 1, wherein the hot melt adhesives with which the leg elastics are secured to the side flaps are continuously applied to the leg elastics in the length direction of the leg elastics.