Patent Application
20120278975
The present invention relates to pants-type disposable wearing articles and, more particularly, to pants-type disposable wearing articles such as disposable diapers, disposable toilet-training pants, disposable incontinent pants, disposable sanitary pants and the like respectively of pants-type, wherein front and rear waist regions are joined together along respective side edges thereof by side seams each including a plurality of sealing spots.
Conventionally, pants-type disposable wearing articles provided with the side seams adapted to join the front and rear waist regions together along side edges of the respective waist regions are known. For example, JP 2008-136651 A (PTL 1) discloses a pants-type disposable wearing article having a front waist region, a rear waist region, a crotch region extending between the front and rear waist regions and side seams provided along the side edges of the front and rear waist spots, each of the side seams including a plurality of sealing spots arranged intermittently in a longitudinal direction of the diaper.
In the pants-type wearing article disclosed in PTL 1, the sealing spot having a smallest width dimension (i.e., a narrowest sealing spot) is positioned at the midpoint of the side seam between the top and bottom segments thereof so that a seam width of the sealing spot may be gradually reduced from the top and bottom segments toward the narrowest sealing spot. With such an arrangement, after the diaper has been used, the front and rear waist regions may be smoothly torn off each other merely by tearing one of the top and bottom segments since the top and bottom segments have a given joint strength but the joint strength of the intermediate segment is relatively low.
An object of the present invention is to provide a pants-type disposable wearing article wherein each of the side seams has a desired joint strength and the joint should not unintentionally be released particularly in the bottom segment during use of the wearing article.
According to the present invention, there is provided a pants-type disposable wearing article having a longitudinal axis and a transverse axis being orthogonal thereto, and including a front waist region, a rear waist region, a crotch region extending between the front and rear waist regions, a waist-opening and side seams by which the front and rear waist regions are joined together along side edges thereof.
According to the present invention, the side seams are respectively formed of a plurality of sealing spots arranged intermittently in a direction along the longitudinal axis and includes a top segment located in the vicinity of the waist-opening and a bottom segment located in the vicinity of the crotch region, and each of the sealing spots has a substantially uniform area and a dimension of the bottom segment in a direction along the transverse axis is larger than a dimension of the top segment in the direction along the transverse axis.
The present invention further includes one or more of the following embodiments.
(1) A dimension of the side seams in the direction along the longitudinal axis is gradually reduced from the outside toward the inside as viewed in the direction along the transverse axis in the bottom segment of the side seams.
(2) The side seams includes an intermediate segment extending between the top segment and the bottom segment; the opposite side edges of the front and rear waist regions respectively include non-elasticized regions formed of a non-elasticized outer sheet, first elasticized regions lying below the non-elasticized regions and formed of the outer sheet and an elasticized inner sheet and second elasticized regions lying below the first elasticized regions and formed of the inner and outer sheets and stretchable leg elastic elements bonded to the inner and outer sheets; and the top segments are formed in the non-elasticized regions, the intermediate segments are formed in the first elasticized regions and the bottom segments are formed in the second elasticized regions.
(3) An area ratio of the sealing spots in the top segment formed in the non-elasticized region is lower than both of an area ratio of the sealing spots in the intermediate segment formed in the first elasticized region and an area ratio of the sealing spots in the bottom segment formed in the second elasticized region.
(4) The sealing spots are arranged obliquely to the longitudinal axis and shaped so that a width dimension of the sealing spots is gradually enlarged in a direction of top-to-bottom.
In the wearing article according to the present invention, each of the sealing spots forming the respective side seams has the substantially uniform area and the dimension of the bottom segment in the direction along the transverse axis is larger than the dimension of the top segment in the direction along the transverse axis. With such an arrangement, the waist-opening having a size sufficient to facilitate the article to be handled and, at the same time, to ensure that the peripheral edges of the leg-openings come in close contact with the wearer's skin at a desired fit. In addition, such unique arrangement reliably eliminates the possibility that the sealing spots in the bottom segment might be unintentionally broken during use of the wearing article.
a)-(b) are diagrams similar to
The diaper 10 has a longitudinal direction Y, a thereto orthogonal transverse direction X, a side facing a wearer's skin, a side facing away from the wearer's skin, a chassis 11 defining an outer shape of the diaper 10 and a liquid-absorbent structure 12 lying on the side of the chassis 11 facing the wearer's skin.
The diaper 10 has a front waist region 13, a rear waist region 14, a crotch region 15 extending between the front and rear waist regions 13, 14, front and rear ends 16, 17 opposed to each other in the longitudinal direction Y and extending in the transverse direction X and opposite side edges 18, 19 opposed to each other in the transverse direction X and extending in the longitudinal direction Y.
The opposite side edges 18, 19 are respectively concavely curved in the crotch region 15 so that these side edges 18, 19 may come in close contact with a wearer's thighs at a desired fit. Opposite side edges 22, 23 of the front waist region 13 which will be referred to hereinafter as front opposite side edges 22, 23 and opposite side edges 24, 25 of the rear waist region 14 which will be referred to hereinafter as rear opposite side edges 24, 25 partially constitute the opposite side edges 18, 19. The front side edges 22, 23 and the rear side edges 24, 25 respectively opposed in a front-back direction of the diaper 10 are joined together by the respective side seams 26 extending intermittently in the longitudinal direction Y to form a waist-opening 27 and a pair of leg-openings 28 (See
The chassis 11 includes a substantially trapezoidal first outer sheet 30 lying on the non-skin-facing side and defining the front waist region 13, a substantially trapezoidal second outer sheet 31 defining the rear waist region 14, a first inner sheet 32 extending in the transverse direction X in the front waist region 13 and bonded to the side of the first outer sheet 30 facing the wearer's skin, a second inner sheet 33 extending in the transverse direction X in the rear waist region 14 and bonded to the side of the second outer sheet 31 facing the wearer's skin and a substantially rectangular intermediate sheet 34 extending between the first and second outer sheets 30, 31 so as to define a midportion of the crotch region 15.
Referring to
The chassis 11 further includes a graphic film 44 made of a plastic material located in the central area of the rear waist region 14 as viewed in the transverse direction X and printed on its side facing away from the wearer's skin with graphics (not shown) or the like adapted to be visually recognized from the outside and a fixing sheet 45 formed of a fibrous nonwoven fabric extending on the side of the chassis 11 facing the wearer's skin across the crotch region 15 into the front and rear waist regions 13, 14. The fixing sheet 45 has a width dimension larger than that of the intermediate sheet 34 and covers, in the central area of the crotch region 15, the entire side of the intermediate sheet 34 facing the wearer's skin.
Along the front end 16 (i.e., a peripheral edge 27a of the waist-opening 27) of the front waist region 13, the first outer sheet 30 is folded inward to form a front turnback 46 within which two or more strand-like first waist elastic elements 47 made of elastomers are contractibly attached under tension. Along the rear end 17 (i.e., a peripheral edge 27a of the waist-opening 27) of the rear waist region 14, the second outer sheet 31 is folded inward to form a rear turnback 48 within which two or more strand-like second waist elastic elements 49 made of elastomers are contractibly attached under tension.
Along respective segments (i.e., peripheral edges 28a of the leg-openings 28) of the opposite side edges 18, 19 of the diaper 10 extending from the bottom of the front waist region 13 to the portions of the crotch region 15 lying adjacently to the front waist region 13, tape-like front leg elastic elements 50R, 50L made of elastomers are attached to the inner surface of the first outer sheet 30. In a similar fashion, along respective segments (i.e., peripheral edges 28a of the leg-openings 28) of the opposite side edges 18, 19 of the diaper 10 extending from the bottom of the rear waist region 14 to the portions of the crotch region 15 lying adjacent to the rear waist region 14, tape-like rear leg elastic elements 51R, 51L made of elastomers are attached to the inner surface of the second outer sheet 31. The rear leg elastic elements 51R, 51L and parts of the front leg elastic elements 50R, 50L are coated on respective outer surfaces thereof with hot melt adhesives (not shown) and attached to the fixing sheet 45 with the hot melt adhesives.
The first and second outer sheets 30, 31 are respectively formed of heat-sealable spun bonded nonwoven fabric having substantially no elastic stretch properties. This fibrous nonwoven fabric has an apparent thickness of about 0.3 to 0.5 mm, a mass per unit area of about 15 to about 40 g/m2, preferably about 25 to about 35 g/m2, a fiber density of about 0.06 to about 0.1 g/cm3, preferably about 0.07 to about 0.09 g/cm3. The first and second outer sheets 30, 31 maybe formed of two or more layers and the respective outermost fiber layers may be formed of crimped spun bonded filament fibers. The first and second outer sheets 30, 31 may be formed of a fibrous nonwoven fabric having an elastic contraction percentage lower than that of the first and second outer sheets 32, 33.
The first and second inner sheets 32, 33 are respectively formed of an elastically stretchable air-through fiber (staple) nonwoven fabric or a spun bonded nonwoven fabric both made of heat-sealable elastomer fibers. Such nonwoven fabric has an apparent thickness of about 0.9 to about 1.0 mm, a mass per unit area of about 20 to about 50 g/m2, preferably about 30 to about 40 g/m2 and a fiber density of about 0.01 to about 0.04 g/cm3, preferably about 0.025 to about 0.035 g/cm3.
The first and second outer sheets 30, 31 have a stretch ratio of about 100 to about 150% and the first and second inner sheets 32, 33 have a stretch ratio of about 150 to 300%. The first and second inner sheets 32, 33 are bonded under tension at a ratio of about 2.0 to about 3.0 to the first and second outer sheets 30, 31 with hot melt adhesives.
Hot melt adhesives 41, 42 used to bond the first and second outer sheets 30, 31 to the first and second inner sheets 32, 33 are not limited to any particular types and various types of adhesives widely used in the related technical field may be used without limitation so long as a desired elasticity for the first and second inner sheets 32, 33 is not affected. To this end, rubber-based adhesives such as SBS (styrene-butadiene-styrene)-adhesives or SIS (styrene-isoprene-styrene)-adhesives, each having a mass per unit area of about 1.0 to 5.0 g/m2 is preferably used for this purpose. Coating patterns for hot melt adhesives 41, 42 may be selected from various well known patterns such as a Q-pattern, a spiral pattern, a dotted pattern and a wavy pattern.
The intermediate sheet 34 and the fixing sheet 45 may be formed of a spun bonded fibrous nonwoven fabric and/or an inelastic air-through fibrous nonwoven fabric similarly to the first and second outer sheets 30, 31.
The liquid-absorbent structure 12 has a vertically long rectangular shape extending across the crotch region 15 into the front and rear waist regions 13, 14 contoured by front and rear ends and opposite side edges which are orthogonal to the front and rear ends. The liquid-absorbent structure 12 comprises a liquid-previous inner sheet 53 lying on the side facing the wearer's skin, a liquid-absorbent core 55 formed of wrapping a liquid-absorbent material assembly including a mixture of fluff pulp fibers and superabsorbent polymer particles with a liquid-dispersant sheet (not shown), a cover sheet 56 lying on the non-skin-facing side so as to cover the entire liquid-absorbent core 55 from the non-skin-facing side and a leakage-barrier sheet 57 formed of a plastic material and sandwiched between the liquid-absorbent core 55 and the cover sheet 56.
The cover sheet 56 has opposite laterals extending outward in the transverse direction X beyond the opposite side edges of the liquid-absorbent core 55. These laterals are partially folded inward to form a pair of sleeve-like side flaps 58R, 58L extending in the direction of the longitudinal axis P. Within the respective side flaps 58R, 58L, four strand-like elastic elements 59, 60 made of elastomers and extending in the longitudinal direction Y are contractibly attached under tension with hot melt adhesives. Of these elastic elements 59, 60, the respective two elastic elements 59a, 60a lying outside are located in the middle of the crotch region 15 as viewed in the longitudinal direction Y and cooperate with the first and second leg elastic elements 50R, 50L, 51R, 51L to define elastic belt-like zones adapted to extend along the wearer's inguinal regions when the diaper 10 is put on the wearer's body. Of the elastic elements 59, 60, the respective two elastic elements 59b, 60b lying inside extend within the respective side flaps 58R, 58L across the crotch region 15 into the front and rear waist regions 13, 14. Under contraction of these elastic elements 59, 60, the opposite laterals of the cover sheet 56 are spaced upward from the inner sheet 53 to form barrier- or gasket-cuffs adapted to prevent sideways leakage of body waste.
The side of the liquid-absorbent structure 12 facing away from the wearer's skin is entirely or partially bonded to the side of the chassis 11 facing the wearer's skin with hot melt adhesives (not shown). A rear end of the liquid-absorbent structure 12 is sandwiched between the second inner sheet 33 and the second outer sheet 31 and thereby body waste should not leak out beyond the rear end of the liquid-absorbent structure 12.
While the ranges covered by the first and second inner sheets 32, 33 are limited to the front and rear waist regions 13, 14, respectively, according to the illustrated embodiment, it is possible to provide the first and second inner sheets 32, 33 so as to extend into the crotch region 15. It is also possible to form the chassis 11 as a whole of inner and outer sheets each defining the outer shape of the diaper 10 instead of providing the fixing sheet 45 on the side facing the wearer's skin so that the diaper 10 as a whole may have stretch properties.
For convenience of illustration,
The top segment 71 is formed in a non-elasticized region 63 defined by the front turnback 46 of the first outer sheet 30 along the side edge 19 of the diaper 10, the intermediate segment 73 is formed in a first elasticized region 64 in which the first outer sheet 30 and the elasticized first inner sheet 32 are present, and the bottom segment 72 is formed in a second elasticized region 65 in which the first inner and outer sheets 30, 32 overlap the first leg elastic element 50R. With regard to dimensions of the respective segments 71, 72, 73 as measured in the longitudinal direction Y, specifically on the assumption that a length l1 of the side edge 19 of the diaper 10 as measured in the longitudinal direction Y is about 100 mm (L-size of the standard infant diaper), a dimension l2 of the top segment 71 ranges about 10 to 30 mm, a dimension l3 of the intermediate segment 73 ranges about 80 to 50 mm, and a dimension l4 of the bottom segment 72 ranges about 10 to 40 mm.
As will be apparent from
Specifically, the distance between each pair of the adjacent sealing spots 29 in the top segment 71 as measured in the longitudinal direction Y is preferably about 2.0 to about 6.0 mm and the distance between each pair of the adjacent sealing spots 29 in the intermediate segment 73 and the bottom segment 72 as measured in the longitudinal direction Y is preferably about 0.5 to about 4.0 mm.
In the bottom segment 72, the sealing spots 29 are arranged close together in comparison to the top segment 71 and the intermediate segment 73 and, in addition, a dimension of the side seam 26 in the transverse direction X is larger than the top segment 71 and the intermediate segment 73. More specifically, while the top segment 71 and the intermediate segment 73 respectively comprise two columns of the sealing spots 29 zigzag arranged, the bottom segment 72 comprises three or more columns of the sealing spots 29 inclusive of the above-mentioned two columns. By dimensioning the bottom segment to be larger than the top segment 71, a substantial circumferential dimension of the diaper 10 in the vicinity of the peripheral edge 28a of the leg-opening can be made narrower than a substantial circumferential dimension of the diaper 10 in the vicinity of the peripheral edge 27a of the waist-opening. Consequentially, the diaper 10 comes in contact about the wearer's thighs at sufficient fit to prevent body waste from leaking sideways and, at the same time, the waist-opening 27 ensures a sufficient dimension to facilitate the diaper 10 to be put on the wearer's body.
In the diaper 10 according to the present embodiment, a width dimension W1 of the side seam in the top segment 71 and the intermediate segment 73 in the transverse direction X is about 0.5 to about 5.5 mm and a width dimension W2 of the side seam in the bottom segment 72 in the transverse direction X is about 3.0 to about 6.0 mm. The sealing spots 29 in the segments 71, 72, 73 have area ratios preferably of about 3.4 to about 4.0%, about 7.5 to about 9.0% and 4.4 to about 5.0%, respectively, of a given width (6 mm) of the non-elasticized region 63, the first elasticized region 64 and the second elasticized region 65.
The respective sealing spots 29 have a substantially uniform area and the bottom segment 72 has a width dimension larger than that of the top segment 71. Under such condition, the bottom segment 72 will have seam strength higher than that of the other segments 71, 73 so long as the top segment 71 and the bottom segment 72 comprise the sheets laminated under the same conditions. The bottom segment 72 extending in the vicinity of the peripheral edge 28a of the leg-opening would otherwise be apt to get wrinkled due to movements of the wearer's leg and to unseal the laminated sheets. However, the bottom segment 73 according to the present embodiment has relatively high seam strength and the seam array should not be unintentionally unsealed. According to the present embodiment, the first leg elastic element 50L made of elastic materials such as urethane is sandwiched between the first inner sheet 32 and the first outer sheet 30 and bonded thereto. Such arrangement would otherwise make it difficult to fusion bond the sheets under pressure and, in consequence, the seam strength would otherwise be lower in the bottom segment 72 than in the top segment 71. However, the width of the bottom segment 72 is dimensioned to be larger than that of the top segment 71 so that the sealing area may be larger in the bottom segment 72 than in the top segment 71 according to the present embodiment. In this way, the bottom segment 72 ensures sufficient seam strength to eliminate the possibility that this segment might be unsealed during use of the diaper 10.
Specifically, as a result of actual measurement using the tensile tester of known art, seam strength per unit area (1 inch) was 10 to 25 N/inch in the top segment 71, 8 to 18 N/inch in the intermediate segment 73 and 10 to 35 N/inch in the bottom segment 72.
The bottom segment 72 is shaped so as to extend obliquely inward from the intermediate segment 73 so that the width of the segment 73 may be gradually enlarged as the segment 72 slopes down inward. More specifically, a dimension of the innermost column in the bottom segment 72 as viewed in the longitudinal direction Y is smaller than that of the column immediately adjacent thereto and the dimension of this adjacent column in the longitudinal direction Y is smaller than that of further outer two columns (defining the top segment 71 and the intermediate segment 73). In this manner, the bottom segment 72 is step wisely configured as a whole.
The bottom segment 72 obliquely extends inward from the intermediate segment 73, facilitating the bottom segment 72 to be torn. In addition, should any amount of body waste flow into the front waist region 13, such amount of body waste can be quickly moved onto the liquid-absorbent structure 12 without the possibility that the amount of body waste might be accumulated on the step defined between the intermediate segment 73 and the bottom segment 72.
Referring to
Each of the sealing spots 29 is relatively small and specifically has an area of about 0.25 to about 2.0 mm. The smaller the size of the sealing spot 29 is, the smaller force there is needed to tear the sealing spot 29. The above-mentioned area of the individual sealing spot 29 is preferable for this reason.
While a dimension l5 of the individual sealing spot 29 in the longitudinal direction Y (i.e., seal dimension) may be appropriately set depending on the seam strength required for each of the segments 71, 72, 73, it is also possible to set the seam strength so that the seam strength may gradually increase from the top segment 71 toward the bottom segment 72. In this case, the seal dimension l5 of the individual sealing spot 29 in the top segment 71 preferably is about 0.5 to about 5.5 mm and the seal dimension l5 of the individual sealing spot 29 in the intermediate segment 73 and the bottom segment 72 is preferably about 3.0 to 6.0 mm.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-011309 | Jan 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/050665 | 1/17/2011 | WO | 00 | 7/11/2012 |
