Patent Publication Number: US-2012035573-A1

Title: Disposable diaper

Description:
TECHNICAL FIELD  
     The present invention relates to disposable diapers. 
     BACKGROUND  
     Conventionally, there are known disposable diapers having a pair of leakage-barrier cuffs extending in parallel in a longitudinal direction on respective sides of their crotch region. 
     For example, the pants-type diaper disclosed in JP 2002-102278 A1 (PTL 1) includes leg-openings annularly provided with leg elastic members on both sides of a crotch region and a pair of leakage-barrier cuffs extending in the longitudinal direction inside the respective leg-openings. The respective cuffs have elasticized edges so as to be elastically stretchable and contractible. These edges are elasticized by elastic members attached thereto under rectilinear tension. With this diaper put on the wearer&#39;s body, peripheral edges of the respective leg-openings are kept in close contact with the wearer&#39;s legs under the effect of the annular leg elastic members and the elasticized edges of the respective paired cuffs are kept in close contact with inguinal regions and/or inner sides of the wearer&#39;s thighs. 
     {Citation List} 
     {Patent Literature} 
     {PTL 1} JP 2002-102278 A1 
     SUMMARY  
     Technical Problem  
     In the diaper disclosed in PTL 1, the leg elastic members are kept in close contact with the respective legs and at the same time the waist elastic members attached under tension to a peripheral edge of the waist-opening are kept in close contact with the waist to stabilize a position of the diaper on the wearer&#39;s body in a vertical direction. In such a state of the diaper, the elasticized edges of the cuffs curved in a U-shape in the longitudinal direction are kept in close contact with the inguinal regions of the wearer from below and kept in close contact with inner sides of the wearer&#39;s thighs obliquely from below to prevent bodily fluids from leaking sideways in the crotch region. However, in diapers of relatively simple construction, there is a diaper which includes a pair of cuffs extending in parallel in the longitudinal direction immediately inside the respective leg-openings but not the elastic members annularly extending along the peripheral edges of the respective leg-openings. With the diaper of such construction put on the wearer&#39;s body, if the diaper slips down under a weight of body waste discharged thereon or due to a movement of the wearer&#39;s body, the cuffs&#39; elasticized edges having been kept in close contact with the wearer&#39;s skin might also slip down and gaps might be formed between the skin and the cuffs&#39; elasticized edges, and eventually bodily fluids might leak through these gaps. 
     An object of this invention is to improve the disposable diaper of prior art so that gaps apt to be formed between the leakage-barrier cuffs and the wearer&#39;s skin during use of the diaper may be effectively lessened. 
     Solution to Problem  
     According to this invention, there is provided a disposable diaper having a longitudinal direction, a transverse direction and a thickness direction being orthogonal to one another and including a front waist region extending forward in the longitudinal direction, a rear waist region extending rearward in the longitudinal direction and a crotch region extending in the longitudinal direction between the front waist region and the rear waist region, wherein the crotch region is formed with a bodily fluid absorbent core having a surface at least partially covered with a liquid-pervious sheet and the crotch region is formed along respective side edges thereof opposed to each other in the transverse direction with a pair of stretchable and contractible leakage-barrier cuffs parallelly extending outboard of the core in the longitudinal direction. 
     The improvement according to this invention is characterized as follows. The front waist region, the rear waist region and the crotch region respectively have an inner side facing the wearer&#39;s skin and an outer side opposed to the inner side. One of the paired cuffs is formed so as to extend outward beyond the core in the transverse direction and includes the inner side, the outer side, an outer side edge extending in parallel to a center line extending in the longitudinal direction so as to bisect a dimension of the crotch region in the transverse direction and at least one first elastic member attached under tension to the outer side edge so as to make the outer side edge stretchable and contractible in the longitudinal direction. The other of the paired cuffs includes a proximal edge fixed to the inner side of the one of the paired cuffs so as to extend in parallel to a center line in the longitudinal direction, a free edge extending in parallel to the proximal edge and at least one second elastic member attached under tension to the free edge so as to make the free edge stretchable and contractible in the longitudinal direction. At least one of the paired cuffs includes a third elastic member extending in the longitudinal direction and attached under tension thereto in the vicinity of the zone in which the proximal edge is fixed thereto. The paired cuffs respectively have opposite ends, as viewed in the longitudinal direction, fixed to the inner side of the diaper. 
     According to one embodiment of this invention, at least one of the front and rear waist regions includes a plurality of waist elastic members attached under tension thereto and one of the first, second and third elastic members intersects with the waist elastic members. 
     According to another embodiment of this invention, at least one of the front and rear waist regions includes a plurality of waist elastic members attached under tension thereto and the third elastic member of the first, second and third elastic members intersects with the waist elastic members. 
     Advantageous Effects of Invention  
     The disposable diaper according to this invention includes a pair of the leakage-barrier cuffs on each side of the crotch region. One of the paired cuffs is formed so as to extend outward beyond the bodily fluid absorbent core and includes the first elastic member attached to the outer side edge and the other of the paired cuffs has the proximal edge fixed to the inner surface thereof and includes the second elastic member attached the free edge extending in parallel to the proximal edge. Any of the paired cuffs includes the third elastic member attached under tension in the longitudinal direction thereto in the vicinity of the zone in which the proximal edge is fixed. With this diaper put on the wearer&#39;s body, one of the paired cuffs is kept in close contact with the wearer&#39;s skin, particularly with the inner side of the wearer&#39;s thigh, under the effect of the first elastic member and the other of the paired cuffs is kept in close contact with the inner side of the wearer&#39;s thigh under the effect of the second elastic member. In addition, these paired cuffs are kept in close contact with the wearer&#39;s skin also under the effect of the third elastic member. Inconsequence, even if the diaper slips down during use thereof, development of gaps between the paired cuffs and the wearer&#39;s skin should be reliably restricted. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS  
       {FIG.  1 } A partially cutaway perspective view of a disposable diaper. 
       {FIG.  2 } A partially cutaway plan view of a developed diaper obtained from the diaper of  FIG. 1 . 
       {FIG.  3 } A partially scale-enlarged diagram of  FIG. 2 . 
       {FIG.  4 } A sectional view taken along line IV-IV in  FIG. 2 . 
       {FIG.  5 } A sectional view taken along line V-V in  FIG. 2 . 
       {FIG.  6 } A partial view of the diaper put on the wearer&#39;s body. 
     
    
    
     DESCRIPTION OF EMBODIMENTS  
     Details of the disposable diaper according to this invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a partially cutaway perspective view of a pants-type disposable diaper  1  as one example of the disposable diaper wherein a longitudinal direction, a transverse direction and a height direction are indicated by double-headed arrows A, B, C being orthogonal to one another. The diaper  1  is symmetric about a center line P-P bisecting a dimension thereof in the transverse direction B and including a crotch panel  6  forming a crotch region  2 , a front panel  7  forming a front waist region  3  extending forward from the crotch region  2  and a rear panel  8  forming a rear waist region  4  extending rearward from the crotch region  2  wherein the front and rear waist panels  7 ,  8  are put flat together along respective opposite laterals thereof and sealed at seams  20  extending continually in the height direction C. These front and rear panels  7 ,  8  cooperate with each other to define a waist-opening  12  and these front and rear panels  7 ,  8  cooperate together to define a pair of leg-openings  13 . The front panel  7  is formed of a first inner sheet  16  and a first outer sheet  17  overlap with each other and bonded together with hot melt adhesives (not shown) intermittently applied thereto wherein these two sheets  16 ,  17  sandwich a plurality of elastic members  18  extending under tension across the front panel  7  in the transverse direction B and a plurality of elastic members  19  extending under tension on laterals of the front panel  7  but not fully extending across the front panel  7 . These elastic members  18 ,  19  are attached to at least one of the sheets  16 ,  17  with hot melt adhesives (not shown). The rear panel  8  is also formed of a second inner sheet  22  and a second outer sheet  23  overlap and bonded together with hot melt adhesives (not shown) wherein these two sheets  22 ,  23  sandwich a plurality of elastic members  24  extending under tension across the rear panel  8  and a plurality of elastic members  25  extending in the transverse direction B without fully extending across the rear panel  8  (See  FIG. 2 ). These elastic members  24 ,  25  are attached to at least one of the sheets  22 ,  23  with hot melt adhesives (not shown). In such diaper  1 , a side facing the wearer&#39;s skin (not shown) is designated herein as an inner side  5   a  and a side facing the wearer&#39;s garment (not shown) is designated herein as an outer side  5   b.    
       FIG. 2  is a partially cutaway plan view of a developed diaper  1   a  obtained by peeling off the front panel  7  and the rear panel  8  of the diaper  1  joined together at the seams  20  in  FIG. 1  from each other to develop these two panels  7 ,  8  in the longitudinal direction A and then stretching the crotch panel  6  and these front and rear panels  7 ,  8  in the longitudinal direction  1  as well as in the transverse direction B. In the developed diaper  1   a,  the crotch panel  6  has a rectangular shape which is relatively long in the longitudinal direction A wherein a section thereof overlapping the front panel  7  is bonded to the first inner sheet  16  with hot melt adhesives (not shown) and a section thereof overlapping the rear panel  8  is bonded to the second inner sheet  22  with hot melt adhesives (not shown). The crotch panel  6  is formed in its midsection in the transverse direction B with a bodily fluid absorbent structure  31  extending in the longitudinal direction A and formed on each side in the transverse direction B with an outer cuff  32  and an inner cuff  33  extending in parallel in the longitudinal direction A. The bodily fluid absorbent structure  31  includes a liquid-pervious cover sheet  31   a  and a bodily fluid absorbent core  31   b  wherein at least the inner surface side of entire surface of the core  31   b  is wrapped with the cover sheet  31   a.    
       FIG. 3  is a scale-enlarged view showing a region encircled by imaginary line III in  FIG. 2 . The outer cuff  32  and the inner cuff  33  are formed of an outer sheet  42  (See  FIG. 4  also) and the outer sheet  42  is folded back to define two layers which are locally joined together along a joint zone  44  by means of one of hot melt adhesives  46  and sealing processing wherein the joint zone  44  extends in parallel to the center line P-P fully between a front end  6   a  and a rear end  6   b  of the crotch panel  6  (See  FIG. 2 ). The outer cuff  32  is defined outside the joint zone  44  as viewed in the transverse direction B of the crotch panel  6  and the inner cuff  33  is defined inside the joint zone  44  wherein the joint zone  44  defines a boundary zone between the outer cuff  32  and the inner cuff  33 . The outer sheet  42  has boundary zone&#39;s elastic member  60  attached thereto under tension so as to extend in parallel to the center line P-P in the longitudinal direction A in the vicinity of the joint zone  44 . The expression “in the vicinity of the joint zone  44 ” used herein means that the boundary zone&#39;s elastic member  60  is spaced from the joint zone  44  in the transverse direction B within 10 mm, more preferably within 5 mm. In an example of the infant diapers using the boundary zone&#39;s elastic member  60  in this manner has, in the longitudinal direction A indicated in  FIG. 2 , a dimension L 2  of the crotch region  2  in a range of 200 to 300 mm, a dimension L 3  of the front waist region  3  in a range of 100 to 150 mm and a dimension L 4  of the rear waist region  4  in a range of 100 to 150 mm and, in the transverse direction B, a dimension W 2  in a range of 150 to 200 mm, a dimension W 3  of the front waist region  3  in a range of 300 to 400 mm and a dimension W 4  of the rear waist region  4  in a range of 300 to 400 mm. A liquid-impervious inner sheet  41  is sandwiched between the outer sheet  42  and the bodily fluid absorbent structure  31  as viewed in the thickness direction of the bodily fluid absorbent structure  31 . 
       FIG. 4  is a sectional view taken along line IV-IV in  FIG. 2 . In the crotch panel  6 , the bodily fluid absorbent structure  31  has an inner surface  36  adapted to come in contact with skin of the wearer (not shown) and an opposite surface  37  which faces, in turn, a leakage-barrier sheet  38  (See also  FIG. 3 ). The leakage-barrier sheet  38  composed of the inner sheet  41  formed of a liquid-impervious plastic film and the outer sheet  42  formed of a nonwoven fabric, more preferably, a nonwoven fabric formed of water-repellent fibers, most preferably, an air-permeable and liquid-impervious nonwoven fabric. The inner sheet  41  is bonded to the opposite surface  37  of the bodily fluid absorbent structure  31  with hot melt adhesives (not shown) and extends across the bodily fluid absorbent structure  31  in the transverse direction B beyond side edges  39  thereof. The outer sheet  42  is bonded to the inner sheet  41  with hot melt adhesives (not shown) to define the outer side  5   b  of the diaper  1  in the crotch region  2  and extends across the bodily fluid absorbent structure  31  in the transverse direction B beyond the side edges  39  of the bodily fluid absorbent structure  31 . The outer sheet  42  extends in the transverse direction B beyond the side edges of the inner sheet  41  and is folded back toward the center line P-P along a first folded zone  43  so as to overlap itself. The outer sheet  42  overlapping itself in this manner is bonded to itself with hot melt adhesives  46  in the joint zone  44 . The outer sheet  42  having been folded back is folded back again along a second folded zone  45  closer to the center line P-P than the first folded zone  43  so as to extend outward in the transverse direction B and a distal end thereof forms a sleeve  48  covering inner side elastic members  49 . The inner side elastic members  49  extend in the longitudinal direction A in parallel to the center line P-P and bonded under tension to the inner surface of the sleeve  48  with hot melt adhesives (not shown). The outer sheet  42  is somewhat sleeve-like also between the first folded zone  43  and the joint zone  44  and outer side elastic members  47  are attached under tension in the longitudinal direction A in parallel to the center line P-P to the inner surface of the first folded zone  43  with hot melt adhesives (not shown). In such crotch panel  6 , a segment of the outer sheet  42  extending between the first folded zone  43  and the joint zone  44  defines the outer cuff  32  adapted to be kept in close contact with the inner sides of the wearer&#39;s thighs and the first folded zone  43  defines the outer side edge of this outer cuff  32 . A segment extending between the joint zone  44  and the sleeve  48  defines the inner cuff  33  adapted to be kept in close contact with the inner sides of the wearer&#39;s thighs and the joint zone  44  defines a proximal edge of the inner cuff  33  and the sleeve  48  defines a free edge adapted to be deformed at a relatively high degree of freedom (See  FIGS. 2 and 3 ). Such inner cuff  33  is formed by an extension of the outer cuff  32  lying on the inner side  5   a  of the diaper  1  so that the inner cuff  33  may rise from the inner side  5   a  as indicated by imaginary lines when the diaper  1  of  FIG. 1  is assembled from the developed diaper  1   a.    
       FIG. 5  is a sectional view taken along line V-V in  FIG. 2 , showing a construction of the front end  6   a  of the crotch panel  6 . In the front end  6   a,  the outer sheet  42  underlying the bodily fluid absorbent structure  31  as seen in  FIG. 5  is bonded to the second inner sheet  22  with hot melt adhesives  56  and the outer cuff  32  is also bonded to the second inner sheet  22 . In the inner cuff  33  in a folded state, the outer sheet  42  is bonded to itself and bonded also to the cover sheet  31   a  with hot melt adhesives  57 . In the rear end  6   b  (See  FIG. 2 ) of the crotch panel  6  also, the outer sheet  42  and the outer cuff  32  formed of this outer sheet  42  are bonded to the first inner sheet  16  in the same manner as those in the front end  6   a.  The inner cuff  33  is folded back in the similar manner to that in  FIG. 4 . One of the outer side elastic members  47 , the inner side elastic member  49  and the boundary zone&#39;s elastic member  60 , more preferably, the boundary zone&#39;s elastic member  60  extends in a stretchable and contractible manner across the elastic members  19 ,  25  in the front and rear panels  7 ,  8 . These elastic members extending across one another cooperate together to surround the associated leg of the wearer and thereby to function in the same manner as the leg elastic members annularly arranged. 
       FIG. 6  is a schematic sectional view of the crotch panel  6  after the developed diaper la constructed as shown in  FIGS. 2 through 5  has been assembled to the diaper  1  of  FIG. 1 , wherein some of the members are not shown for convenience of illustration but the positions of these members are the same as the positions in the sectional view of  FIG. 4 . In  FIG. 6 , a portion of the inner side  62  of the wearer&#39;s thigh and a portion of the inguinal region being contiguous thereto are indicated by imaginary lines, respectively. In the longitudinal direction A, the crotch panel  6  of the diaper  1  bows in a U-shape and is suspended at the front end  6   a  and the rear end  6   b  from the front panel  7  and the rear panel  8 , respectively. In the transverse direction B, the crotch panel  6  bows to be convex downward of the diaper  1 . Upon contraction of the outer side elastic members  47  and the inner side elastic members  49 , the outer cuff  32  and the inner cuff  33  extend upward from the respective side edges  39  of the bodily fluid absorbent structure  31 . In consequence, the first folded zone  43  of the outer sheet  42  defining the lower edge of the outer cuff  32  as viewed in  FIG. 6  comes in contact with the inner side  62  of the wearer&#39;s thigh, and the second folded zone  45  of the inner cuff  33  is unfolded so that the sleeve  48  now defining the upper edge of the inner cuff  33  may come in contact with the inner side  62  of the wearer&#39;s thigh or the inguinal region  63 . In this way, these paired outer cuffs  32  and inner cuffs  33  respectively function as leakage-barrier cuffs adapted to prevent bodily fluids from leaking sideways from the diaper  1 . Along the joint zone  44  in the outer sheet  42  defining the proximal edge of the inner cuff  33 , the outer cuff  32  and the inner cuff  33  are branched from each other and the joint zone  44  is elastically kept in contact with the inner side  62  of the wearer&#39;s thigh under the effect of the boundary zone&#39;s elastic member  60 . 
     With the diaper  1  put on the wearer&#39;s body in a preferred manner, the inner side  62  of the wearer&#39;s thigh is at the position indicated by the imaginary lines  62  in  FIG. 2  and the outer side elastic members  47 , the inner side elastic members  49  and the boundary zone&#39;s elastic member  60  lying at the bottom of the crotch region  6  as viewed in  FIG. 1  are stretched and deformed inward in the transverse direction B so as to get close to the center line P. The outer side elastic members  47  of the outer cuff  32  and the inner side elastic members  49  of the inner cuff  33  are elastically put in contact with the inner side  62  of the wearer&#39;s thigh in the longitudinal direction C of the diaper  1  as well as in the transverse direction B extending from the inner side toward the outer side of the diaper  1  but these elastic members do not annularly tighten the wearer&#39;s thigh. Assuming that the outer cuff  32  and the inner cuff  33  have no additional features, the first folded zone  43  in the outer cuff  32  and the sleeve  48  of the inner cuff  33  would be spaced from the inner side  62  of the wearer&#39;s thigh when the diaper  1  unintentionally slips down along the wearer&#39;s body so as to develop gaps between these cuffs  32 ,  33  and the inner side  62  of the wearer&#39;s thigh, causing bodily fluids to leak sideways through such gaps and deteriorating the desired function of the outer cuff  32  and the inner cuff  33  as the leakage-barrier cuffs. However, the outer sheet  42  in the diaper  1  includes the boundary zone&#39;s elastic member  60  provided in the vicinity of the joint zone  44  about which the outer cuff  32  and the inner cuff  33  are branched from each other functions to keep the outer cuff  32  and the inner cuff  33  in close contact with the inner side  62  of the wearer&#39;s thigh in the joint zone  44 . In this way, a movement of the outer cuff  32  away from the inner side  62  of the wearer&#39;s thigh due to unintentional slip down of the diaper  1  can be restricted by cooperation of the outer side elastic members  43  and the boundary zone&#39;s elastic member  60 , and a movement of the inner cuff  33  away from the inner side  62  of the wearer&#39;s thigh can be restricted by cooperation of the inner side elastic members  49  and the boundary zone&#39;s elastic member  60  to prevent the gaps causing leakage of bodily fluids from developing between these cuffs  32 ,  33  and the inner side  62  of the wearer&#39;s thigh. While the boundary zone&#39;s elastic member  60  may be bonded to the outer cuff  32  or the inner cuff  33  in the vicinity of the joint zone  44 , this elastic member  60  is preferably bonded to the outer sheet  42  at a position inside the joint zone  44 , more specifically, at a position defined between the joint zone  44  and the center line P-P as exemplarily shown in  FIGS. 2 and 4 . While the boundary zone&#39;s elastic member  60  is not limited to the illustrated example and may be formed of a plurality of rubber threads, it is preferred in any cases that a force F 0  which is needed to stretch the joint zone  44  from a state of under contraction of the boundary zone&#39;s elastic member  60  by 20% should be higher than a force F 2  which is needed to stretch the inner side elastic members  49  from the state thereof under contraction by 20% rather than a force F 1  which is needed to stretch the outer side elastic members  47  from the state thereof under contraction by 20% and the inner cuff  33  can be prevented from moving away from the wearer&#39;s skin. If any elastic members alternative to the boundary zone&#39;s elastic member  60  are attached to the outer sheet  42  at a position spaced inward from the joint zone  44 , for example, in the infant diaper  1 , at a position spaced inward from the joint zone  44  by 10 mm or more, an amount by which such elastic members can be stretched toward the center line P-P will be restricted by the inner side  62  of the wearer&#39;s thigh in comparison to the exemplarily illustrated boundary zone&#39;s elastic member  60 . Such elastic members being alternative to the boundary zone&#39;s elastic member  60  are undesirable because the closer to the midsection of the diaper  1  the elastic members being alternative to the boundary zone&#39;s elastic member  60  are located, the lower the force keeping the cuffs in close contact with the inner side  62  of the wearer&#39;s thigh in the transverse direction B becomes and the effect to restrict the movement of the outer cuff  32  and the inner cuff  33  will be correspondingly deteriorated. While this invention has been described above exemplarily based on the pants-type disposable diaper  1 , this invention is applicable also to a so-called open-type diaper having the front waist region  2  and the rear waist region  3  are detachably connected to each other by means of fastener. 
     REFERENCE SIGNS LIST  
     
         
           1  disposable diaper 
           2  crotch region 
           3  front waist region 
           4  rear waist region 
           5   a  inner surface 
           5   b  outer surface 
           18  elastic members 
           19  elastic members 
           24  elastic members 
           25  elastic members 
           31   a  liquid-pervious sheet (cover sheet) 
           31   b  core 
           32  cuffs (outer cuffs) 
           33  cuffs (inner cuffs) 
           43  outer side edges (first folded zones) 
           44  proximal edges (joint zones) 
           47  first elastic members (outer side elastic members) 
           49  second elastic members (inner side elastic members) 
           60  third elastic members (boundary zones&#39; elastic members) 
         A longitudinal direction 
         B transverse direction 
         P center line