Patent Publication Number: US-2011054434-A1

Title: Disposable pants-type diaper

Description:
TECHNICAL FIELD 
     The present invention relates to disposable pants-type diapers with which the wearer&#39;s skin would not be soiled with urine and/or feces. 
     RELATED ART 
     It is well known to provide diapers each with a structure serving to prevent urine and feces from being mixed with each other inside the diaper put on the wearer&#39;s body. For example, in the case of the disposable pants-type diaper described in JP 2007-296314 A (PATENT DOCUMENT 1), a nonwoven fabric piece defining a separator serving to prevent urine and feces from being mixed with each other is provided in the crotch region and this nonwoven fabric piece is fixed along the opposite side edges thereof to the inner surface of the diaper. The nonwoven fabric piece has a front end and a rear end both extending in the transverse direction of the diaper and these two ends are partially integrated together on a center line bisecting a width dimension of the diaper. The diaper is formed with a body waste retaining space symmetrically in a front-back direction about the spacer which functions to divide this space into front and rear body waste retaining sub-spaces so that urine and feces may be separately retained. 
     PATENT DOCUMENT 1: JP 2007-296314 A 
     DISCLOSURE OF THE INVENTION 
     Problem to be Solved by the Invention 
     In the case of this diaper of prior art, the separator may collapse onto the liquid-pervious inner sheet covering the absorbent core as the wearer takes a sitting posture and, in consequence, feces once having been retained in the body waste retaining sub-space defined behind the separator may be partially extruded forward beyond the separator until the wearer&#39;s external genital may be soiled with feces. In addition, the core lying in the crotch region may be crooked in the transverse direction and pressed against the wearer&#39;s thighs as the wearer moves his or her legs to be closed up to the wearer&#39;s skin. Eventually, the internal volume of the body waste retaining space may be unacceptably reduced and the wearer&#39;s skin may be soiled with excess feces. 
     In view of the problem as has been described above, it is a principal object of the present invention to improve the disposable pants-type diaper so that the separator may fulfill its function without being affected by variation of the diaper wearer&#39;s posture. 
     Measure to Solve the Problem 
     The object set forth above is achieved, according to the present invention, by an improvement in a disposable pants-type diaper having a front-back direction, a transverse direction and a vertical direction being orthogonal one to another and comprising a crotch region, a front waist region extending forward from the crotch region and a rear waist region extending rearward from the crotch region wherein the crotch region includes a bodily fluid absorbent structure comprising a liquid-pervious inner sheet, a liquid-impervious outer sheet and a bodily fluid absorbent core sandwiched between the inner and outer sheets and curved with inner sheet inside and the crotch region is additionally formed with a separator adapted to separate urine and feces from each other. 
     The improvement according to the present invention is characterized in aspects as follow. The innermost sheet member bonded to the inner sheet to be interposed between skin of wearer of the diaper and the inner sheet is adapted to be partially spaced upward from the inner sheet in the vertical direction and thereby to form a body waste retaining space having a front opening allowing urine to flow into the body waste retaining space and a rear opening allowing feces to move into the body waste retaining space. A portion of the innermost sheet member extending in the front-back direction between the front opening and the rear opening is folded to be opposed to each other in the front-back direction and directly or indirectly bonded to itself along a center line extending in the transverse direction and bisecting a dimension of the diaper in the front-back direction so that the portion droops down toward the crotch region and a lower end thereof is joined to the inner sheet to form the separator. The separator is provided along the center line with a sheet member having a thickness in the front-back direction in a range of 1 to 10 mm, a width in the transverse direction in a range of 10 to 70 mm and a height in the vertical direction in a range of 30 to 100% of a dimension of the separator in the vertical direction and functioning to restrict a degree of deformation potentially occurring in the separator formed of the innermost sheet material. 
     According to one preferred embodiment of the present invention, the sheet member has a level of stiffness in a range of 40 to 130N based on Procedure D of Stiffness Measuring Method specified by Section 6 of JIS K 6400-2. 
     According to another preferred embodiment of the present invention, the sheet member is attached to the separator on a front surface of the separator, a rear surface of the separator or between the opposed and joined portions of the innermost sheet member. 
     EFFECT OF THE INVENTION 
     In the disposable pants-type diaper according to the present invention, the innermost sheet member forming the separator adapted to separate urine and feces from each other and thereby to prevent urine and feces from being mixed with each other is provided with the sheet member having a thickness in the front-back direction in a range of 1 to 10 mm, a width in the transverse direction in a range of 10 to 70 mm and a height in the vertical direction in a range of 30 to 100% of a dimension of the separator in the vertical direction and functioning to restrict the separator from being deformed. With this arrangement, the separator can fulfill its primary function without being readily crooked even if the diaper wearer&#39;s posture changes in various ways. The separator provided with this sheet member serves also to restrict the bodily fluid-absorbent core from being crooked to be pressed against the diaper wearer&#39;s skin. In this way, the separator is able to prevent the internal volume of the body waste retaining space from being unacceptably reduced due to such crooking of the core. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially cutaway perspective view of a pants-type diaper according to the present invention. 
         FIG. 2  is a plan view showing the pants-type diaper having front and rear waist regions thereof unsealed from each other and flatly developed. 
         FIG. 3  is a sectional view taken along the line in  FIG. 1 . 
         FIG. 4  is an overhead view of the pants-type diaper as viewed from above in a direction indicated by the arrows IV-IV in  FIG. 3 . 
         FIG. 5  is a partially cutout perspective view of one preferred embodiment of the pants-type diaper according to the present invention. 
         FIG. 6  is a sectional view taken along the line VI-VI in  FIG. 5 . 
         FIG. 7  is a view similar to  FIG. 6 , showing another preferred embodiment of the present invention. 
     
    
    
     IDENTIFICATION OF REFERENCE NUMERALS USED IN THE DRAWINGS 
     
         
           1  pants-type diaper 
           2  inner sheet 
           3  outer sheet 
           4  absorbent core 
           6  crotch region 
           6   a  lowermost portion of crotch region 
           7  front waist region 
           8  rear waist region 
           10  chassis 
           12  leg-openings 
           20  innermost sheet member 
           20   a  separator 
           31  body waste retaining space 
           33  front opening 
           34  rear opening 
           35  lower end 
           45  liquid-absorbent structure 
           81  sheet member (deformation restricting sheet) 
           120  innermost sheet member 
         A front-back direction 
         B transverse direction 
         C vertical direction 
         K dimension of separator in vertical direction 
         L height 
         M width 
         N thickness 
         P-P center line 
       
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Details of the disposable pants-type diaper according to the present invention will be more fully understood from the description given hereunder with reference to the accompanying drawings. 
       FIG. 1  is a partially cutaway perspective view showing the disposable pants-type diaper  1  as put on the wearer&#39;s body wherein a front-back direction, a transverse direction and a vertical direction of the diaper  1  are respectively indicated by the double-headed arrows A, B and C which are orthogonal one to another. The diaper  1  includes a pants-shaped chassis  10  comprising a liquid-pervious inner sheet  2 , a liquid-impervious outer sheet  3  and a bodily fluid-absorbent core  4 . The chassis  10  has a crotch region  6 , a front waist region  7  extending forward from the crotch region  6  and a rear waist region  8  extending rearward from the crotch region  6 . The front and rear waist regions  7 ,  8  are put flat and sealed together along respective pairs of side edges  7   a ,  7   a  and  8   a ,  8   a  of these waist regions  7 ,  8 , more specifically, at joints  9  arranged intermittently in the vertical direction as viewed in  FIG. 1  along these side edges  7   a ,  7   a  and  8   a ,  8   a  and thereupon a waist-opening  11  and a pair of leg-openings  12  are formed. Along a periphery  11   a  of the waist-opening  11 , a plurality of waist elastic members  14   a  extending in a circumferential direction is sandwiched between the inner and outer sheets  2 ,  3  and bonded under tension to at least one of the inner and outer sheets  2 ,  3 . Along a periphery of each of the leg-openings  12 , a plurality of leg elastic members  14   b  extending in the circumferential direction is sandwiched between the inner and outer sheets  2 ,  3  and bonded under tension to at least one of these inner and outer sheets  2 ,  3 . Three components, i.e., the leg elastic members  14   b  and the inner and outer sheets  2 ,  3  cooperate together to define respective elastic regions  41  surrounding the wearer&#39;s legs. Of the diaper  1 , at least the crotch region  6  includes a bodily fluid absorbent structure  45  comprising the inner and outer sheets  2 ,  3  and the absorbent core  4  sandwiched therebetween. The bodily fluid absorbent structure  45  extends in the front-back direction A and curves convexly downward to define a bottom portion  6   a  of the crotch region  6 . 
       FIG. 2  is a partially cutaway perspective view showing the diaper  1   a  as after the front and rear waist regions  7 ,  8  of the diaper  1  have been unsealed at the joints  9  and flatly developed as a whole in the front-back direction A as well as in the transverse direction B wherein such developed diaper  1   a  is shown as viewed from its inner side. In the state of such developed diaper  1   a , the chassis  10  in  FIG. 1  appears as a concave shaped flattened chassis  10   a . The periphery  11   a  of the waist-opening  11  in  FIG. 1  appears herein as a front end  7   b  and a rear end  8   b  of the flattened chassis  10   a  and the peripheries  13  of the respective leg-openings  12  appear herein as the crotch region&#39;s side edges  13   b  of the flattened chassis  10   a . While the crotch region&#39;s side edges  13   b  convexly curve toward the center line P-P extending in the front-back direction A to bisect a dimension of the flattened chassis  10   a  in the transverse direction X, the respective pairs of side edges  7   a ,  7   a  and  8   a ,  8   a  of the front and rear waist regions  7 ,  8  extend substantially in parallel to this center line P-P. The absorbent core  4  also is concave shaped and is formed of a mixture  4   a  of fluff pulp fibers and super-absorbent polymer particles wrapped with a bodily fluid-absorbent and highly dispersant wrapping sheet  4   b  such as a tissue paper. In the flattened chassis  10   a , the innermost sheet member  20  made of, for example, a hydrophobic nonwoven fabric, a plastic film or a composite sheet thereof, more preferably, a hydrophobic and liquid-impervious nonwoven fabric, a plastic film or a composite sheet thereof is attached to the inner sheet  2  defining the inner surface of the flattened chassis  10   a  in the crotch region  6  so that the innermost sheet member  20  may define a separator  20   a  (See  FIG. 3 ). Such flatly developed diaper  1   a  is formed symmetrically about the center line P-P extending in the front-back direction A. The lowermost portion  6   a  of the crotch region  6  lies on the transverse center line Q-Q bisecting a dimension of the flatly developed diaper  1   a  in the front-back direction A. 
     The innermost sheet member  20  is attached to the flattened chassis  10   a  so that the innermost sheet member  20  may be interposed between the inner sheet  2  and the diaper wearer&#39;s skin (not shown) when the diaper  1  is put on the wearer&#39;s body. The innermost sheet member  20  has side edges  23  respectively fixed to the crotch region&#39;s side edges  13   b  by hot melt adhesive  24 , a front edge  21  lying before the lowermost portion  6   a  of the crotch region  6  and extending in the transverse direction B between the side edges  23 ,  23  and a rear edge  22  lying behind the lowermost portion  6   a  of the crotch region  6  and extending in the transverse direction B between the side edges  23 ,  23 . The innermost sheet member  20  in the illustrated embodiment is not bonded to the inner sheet  2  and adapted to be spaced from the inner sheet  2  except the side edges  23  so that a tunnel- or pocket-like body waste retaining space  31  extending from the front edge  21  to the rear edge  22  may be defined between the innermost sheet member  20  and the inner sheet  2 . Along the front edge  21  and the rear edge  22 , the innermost sheet member  20  is folded to form a sleeve  21   a  and a sleeve  22   a , respectively. These sleeves  21   a ,  22   a  contain therein a front elastic member  21   b  and a rear elastic member  22   a  attached under extension thereto, respectively, to define front elastic region  42  and a rear elastic region  43  both extending between the crotch region&#39;s side edges  13   b . These elastic regions  42 ,  43  intersect with the elastic regions  41  of the flattened chassis  10   a . A distance Hf from the transverse center line Q-Q to the front edge  21  is substantially equal to a distance Hr from the transverse center line to the rear edge  22 . 
     The innermost sheet member  20  is provided on the front edge  21  with a deformation restricting sheet member  81  on the center line P-P extending in the front-back direction A. The deformation restricting sheet member  81  may be provided in the form of a block made of a sponge, a foamed polyurethane, a foamed polystyrene, a foamed polyethylene, a felt or a nonwoven fabric having a flexibility sufficient to be easily deformed under a body weight of the wearer of the diaper  1  and, more preferably, having an elastic recovery properties also sufficient for a rapid recovery after deformation. The innermost sheet member  20  is provided on the rear edge  22  with a region  82  indicated by a imaginary line. The deformation restricting sheet member  81  is bonded to this region  82  when the side edges  7   a ,  7   a  and  8   a ,  8   a  of the flattened chassis  1   a  are joined together to obtain the diaper  1  (See  FIGS. 3 and 4 ). 
       FIG. 3  is a sectional view taken along the line in  FIG. 1  and the line corresponds to the center line P-P extending in the front-back direction A in  FIG. 2 . In the pant-shaped chassis  10 , the front and rear waist regions  7 ,  8  are joined together along the respective side edges  7   a ,  7   a  and  8   a ,  8   a  thereof. The crotch region  6  curves in U-shape as viewed in the front-back direction A and the lowermost portion  6   a  of the crotch region  6  defines a bottom of this U-shaped curve. The crotch region&#39;s side edges  13   b  appear in  FIG. 3  as the peripheral edges  13  defining the leg-openings  12 . The innermost sheet member  20  has the front edge  21  and the rear edge  22  thereof bonded to each other by the deformation restricting sheet member  81  and the portion  36  shown in  FIG. 2  to extend in the front-back direction A between the front edge  21  and the rear edge  22  sags toward the lowermost portion  6   a  to form the separator  20   a  partitioning the crotch region  6  into a front half and a rear half. The deformation restricting sheet member  81  has a thickness N in the front-back direction A and a height L in the vertical direction and is attached to the innermost sheet member  20  by adhesion or sealing. The region in which the deformation restricting sheet member  81  is joined to the rear edge  22  is designated by a reference numeral  82 . The separator  20   a  has its lower end  35  bonded to the lowermost portion  6   a  of the crotch region  6  by adhesive (not shown) and has height K corresponding to a dimension from the deformation restricting sheet member  81  to the inner sheet  2  in the lowermost portion  6   a  of the crotch region  6 . In the body waste retaining space  31  formed by cooperation of the innermost sheet member  20  with the inner sheet  2 , the front edge  21  of the innermost sheet member  20  is adapted to be spaced from the inner sheet  2  and thereby to define a front opening  33  and the rear edge  22  is adapted to be spaced from the inner sheet  2  and thereby to define a rear opening  34 . 
       FIG. 4  is an overhead view of the diaper  1  of  FIG. 1  as viewed from above the waist-opening  11  in a direction indicated by the arrows IV-IV in  FIG. 3 . The deformation restricting sheet member  81  has a width M in the transverse direction B and each of the front and rear ends  21 ,  22  is bisected in the transverse direction B by the deformation restricting sheet member  81  divided in two, i.e., right segments  21   R ,  22   R  adapted to be put in contact with a right leg of the diaper wearer (not shown) and left segments  21   L ,  22   L , adapted to be put in contact with a left leg of the diaper wearer. The right segments  21   R ,  22   R  cooperate with each other to define a laterally facing V-shaped space so that the wearer&#39;s right leg may be guided through this laterally facing V-shaped space. In a similar manner, the left segments  21   L ,  22   L , cooperate with each other to define a laterally facing V-shaped space so that the wearer&#39;s left leg may be guided through this laterally facing V-shaped space. As illustrated, the respective leg-openings  12  of the chassis  10  have a right leg peripheral edge  13   R  and a left leg peripheral edge  13   L . The respective peripheral edges  13   R ,  13   L , comprise upper segments  15   a  not overlapping the side edges  23  of the innermost sheet member  20  and lower segments  15   b  overlapping the side edges  23  and bonded thereto (See  FIG. 3  also). In  FIG. 4 , respective ranges of these upper segments  15   a  and lower segments  15   b  are indicated by double-headed arrows G and H. 
     Sequence in which the diaper  1  may be put on the wearer&#39;s body will be described below together with behavior of the diaper  1 . First, the front and rear waist regions  7 ,  8  of the chassis  10  may be spaced from each other in the front-back direction A and then the waist-opening  11  may be sufficiently broadened as seen in  FIGS. 1 and 4 . Thereby the front edge  21  of the separator  20   a  formed of the innermost sheet member  20  is deformed so that the right segment  21   R  and the left segment  21   L , are curved in V-shape facing forward in the front-back direction A around the deformation restricting sheet member  81 . In a similar manner, the rear edge  22  is deformed so that the right segment  22   R  and the left segment  22   L  are curved in V-shape facing rearward in the front-back direction A (See  FIG. 4 ). Consequently, the front opening  33  and the rear opening  34  for the body waste retaining space  31  are automatically broadened (See  FIG. 3 ). The left segments  21   L ,  22   L , are spaced from each other in the front-back direction A at the same moment that the right segments  21   R ,  22   R  are spaced from each other in the front-back direction A. Now the diaper wearer (not shown) may guide his or her right leg into an opening  41   R  for the right leg defined by the upper segment  15   a  of the right leg peripheral edge  13   R , the right segment  21   R  of the front edge  21  and the right segment  22   R  of the rear edge  22 . Then the wearer may guide his or her right leg into the leg-opening  12  for the right leg defined by the upper segment  15   a  and the lower segment  15   b  of the right leg peripheral edge  13   R . Without interruption, the wearer may guide his or her left leg into an opening  41   L  for the left leg defined by the upper segment  15   a  of the left leg peripheral edge  13   L , the left segment  21   L , of the front edge  21  and the left-hand segment  22   L , of the rear edge  22 . Then the wearer may guide his or her right leg into the leg-opening  12  for the left leg defined by the upper segment  15   a  and the lower segment  15   b  of the left leg peripheral edge  13   L . 
     In the diaper  1  after it has been put on the wearer&#39;s body, the peripheral edges  13  of the respective leg-openings  12 , i.e., the right leg peripheral edge  13   R  and the left leg peripheral edge  13   L , are elastically contractible in a circumferential direction thereof, on one hand, and the front edge  21  and the rear edge  22  of the separator  20   a  are elastically contractible in the transverse direction B, on the other hand. With such arrangement, the upper segment  15   a  of the peripheral edge  13   R  for the right leg and the right segments  21   R ,  22   R  of the separator  20   a  are elastically put in close contact around the right leg in the vicinity of the right leg&#39;s inguinal region to form a primary seal  51   R  (See  FIG. 4 ) serving to prevent leakage of bodily fluids. Below the primary seal  51   R , the lower segment  15   b  and the upper segment  15   a  of the peripheral edge  13   R  for the right leg are integrated to form a secondary seal  52   R  (See  FIG. 4 ) serving to prevent leakage of bodily fluids. Function of this secondary seal  52   R  is similar to that of the leg seal in the conventional pants-type diaper. The arrangement and function as have been described just above are true with respect to the left leg. Specifically, the upper segment  15   a  of the peripheral edge  13   L , for the left leg and the left segments  21   L ,  22   L  of the separator  20   a  are elastically put in close contact around the left leg in the vicinity of the left leg&#39;s inguinal region to form a primary seal  51   L , serving to prevent leakage of bodily fluids. Below the primary seal  51   L , the lower segment  15   b  and the upper segment  15   a  of the peripheral edge  13   L , for the left leg are integrated to form a secondary seal  52   L  serving to prevent leakage of bodily fluids. The diaper  1  having been put on the wearer&#39;s body may be sufficiently pulled up along the body to assure that a central segment of the separator  20   a  as viewed in the transverse direction B along which the deformation restricting sheet member  81  is attached thereto comes in contact with the wearer&#39;s skin between the wearer&#39;s external genital and anus. 
     With the diaper  1  put on the wearer&#39;s body in the state as has been described above, the portion  36  of the separator  20   a  is positioned to divide the wearer&#39;s crotch region into a front half and a rear half. In the front half of the wearer&#39;s crotch region, the wearer&#39;s external genital lying before the front edge  21  is exposed in the front opening  33  and, in the rear half of the wearer&#39;s crotch region, the wearer&#39;s anus lying behind the rear edge  22  is exposed in the rear opening  34 . Consequentially, it is assure that urine discharged by the wearer flows through the front opening  33  into the pocket-like body waste retaining space  31  and feces excreted by the wearer moves through the rear opening  34  into the body waste retaining space  31 . In this way, it is possible for the diaper  1  to prevent urine and/or feces from coming in contact with the wearer&#39;s skin by the presence of the separator  20   a . In addition, the deformation restricting sheet member  81  attached to the separator  20   a  functions to restrict the bodily fluid-absorbent structure from being crooked along the center line P-P in the front-back direction and thereby pressed against the diaper wearer&#39;s skin as the diaper wearer moves his or her legs to be closed up. Thereby the deformation restricting sheet member  81  prevents the internal volume of the body waste retaining space  31  from being unacceptably reduced. The deformation restricting sheet member  81  further prevents the bodily fluid-absorbent structure  45  from moving close to the front opening  33  and/or the rear opening  34  and thereby closing these openings  33 ,  34 . 
     The shape of the bodily fluid-absorbent structure  45  behaving to be crooked in this manner is indicated by imaginary lines in  FIG. 1  and  FIG. 5 . The bodily fluid-absorbent structure  45  in  FIG. 1  as well as the bodily fluid-absorbent structure  122  in  FIG. 5  corresponding to the bodily fluid-absorbent structure  45  potentially behaves to move in opposite directions of the arrows E and F to be crooked and pressed in the direction of the arrow G against the wearer&#39;s skin. However, the deformation restricting sheet member  81  is able to restrict such movement. 
     In response to change of the diaper wearer&#39;s posture from sitting posture to standing posture, the deformation restricting sheet member  81  accelerates the separator  20   a  to return from its state collapsing on the inner sheet  2  during sitting posture of the diaper wearer to the initial state in which the separator  20   a  extends downward from the region defined between the front and rear openings  33 ,  34  toward the inner sheet  2  as shown in  FIG. 3  and thereby allows the separator  20   a  to fulfill its primary function. In the case of the separator  20   a  extending downward as seen in  FIG. 3  having its lower end  35  bonded to the lowermost portion  6   a  of the crotch region  6 , the separator  20   a  extending between the front edge  21  and the lower end  35 , i.e., between the rear edge  22  and the lower end  35  can quickly recover its normal state as seen in  FIG. 3  even if the separator  20   a  has collapsed onto the inner sheet  2 . Specifically, the deformation restricting sheet member  81  having stiffness higher than the innermost sheet member  20  is attached to the separator  20   a  and therefore the separator  20   a  can easily recover its primary state merely as the front edge  21  is pulled forward and the rear edge  22  is pulled rearward. 
     The deformation restricting sheet member  81  functioning in the manner as has been described above has the width M preferably in a range of 10 to 70 mm, more preferably in a range of 30 to 60 mm, the thickness N preferably in a range of 1 to 10 mm, more preferably in a range of 3 to 7 mm and the height L preferably in a range of 30 to 100%, more preferably in a range of 50 to 80% of the height K of the separator  20   a . If any one or more of these dimensions of the deformation restricting sheet member  81  is or are out of the ranges as have been described, feeling to wear the diaper  1  will be deteriorated and/or deformation restricting function of the deformation restricting sheet member  81  in the separator  20   a  and the bodily fluid-absorbent structure  45  will be insufficient. In order that the deformation restricting sheet member  81  can fulfill its primary function of enhancing the stiffness of the separator  20   a  in the central segment thereof as viewed in the transverse direction B, the deformation restricting sheet member  81  is formed of a material preferably having stiffness in a range of 40 to 130N, more preferably in a range of 60 to 90N based on Procedure D of Stiffness Measuring Method specified by Section 6 of JIS K 6400-2. If the stiffness is less than 40N, the deformation restricting sheet member  81  will be too flexible to fulfill its function and if the stiffness exceeds 130N, the deformation restricting sheet member  81  will make the separator  20   a  locally stiff beyond an allowable limit. In addition to the requirements as have been described above, the deformation restricting sheet member  81  preferably has an elastically restoring force. 
     In the diaper  1 , the front edge  21  of the innermost sheet member  20  defining the separator  20   a  partially defines the peripheral edge of the front opening  33 . As viewed in the front-back direction A, the front edge  21  lies behind the wearer&#39;s external genital and positioned so that the external genital can be reliably exposed in the front opening  33 . While the front edge  21  is exemplarily illustrated to extend linearly in the transverse direction B, it is also possible to form the front edge  21  to curve convexly toward the transverse center line Q-Q. The rear edge  22  of the innermost sheet member  20  partially defines the peripheral edge of the rear opening  34 . As viewed in the front-back direction A, the rear edge  22  lies before the wearer&#39;s anus and positioned so that the anus can reliably face the rear opening  34 . While such rear edge  22  is exemplarily illustrated to extend linearly in the transverse direction B, it is possible to form the rear edge  22  to curve convexly toward the transverse center line Q-Q. 
     In the crotch region  6  of the flattened chassis  10   a  shown by  FIG. 2 , the inner and outer sheets  2 ,  3  put flat together define side flaps  25  outside the liquid-absorbent core  4 . When the crotch region  6  is curved in U-shape under contraction of the elastic regions  41  and thereupon the diaper  1  is put into the state as illustrated by  FIG. 1 , the side flaps  25  behave to raise themselves along side edges  4   c  of the core  4  in the vicinity of the transverse center line Q-Q, i.e., in the vicinity of the lowermost portion  6   a  of the crotch region  6 . The innermost sheet member  20  having the side edges  23  bonded to the inner surface of the elastic regions  41  pulls the side flaps  25  inward in the transverse direction of the diaper  1 , i.e., toward the center line P-P extending in the front-back direction as the waist-opening  11  is broadened. In consequence, the behavior of the side flaps  25  to raise themselves is further enhanced. Such behavior of the side flaps  25  becomes further significant as the front edge  21  and the rear edge  22  elastically contract. The side flaps  25  having such behavior come in close contact with the wearer&#39;s thighs from below with respect to the diaper  1  and thereby effectively prevent bodily fluids from leaking out along the wearer&#39;s thighs. 
     To implement the present invention, a liquid-pervious sheet material such as a nonwoven fabric or a perforated plastic film may be used as the inner sheet  2 . A liquid-impervious sheet material such as a plastic film or a composite sheet consisting of a plastic film and a nonwoven fabric may be used as the outer sheet  3 . Fluff pulp fibers or a mixture of fluff pulp fibers and super-absorbent polymer particles wrapped with an appropriate sheet material such as a tissue paper may be used as the liquid-absorbent core  4 . A hydrophobic sheet material such as a nonwoven fabric or a plastic film, more preferably, a hydrophobic and liquid-impervious sheet material may be used as the innermost sheet member  20 . While the innermost sheet member  20  are preferably provided along the front edge  21  and the rear edge  22  with the elastic members  21   b ,  22   b  attached under tension thereto so that the innermost sheet member  20  may be elastically contracted, it is possible to eliminate use of the elastic members  21   b ,  22   b  by using an elastic sheet material adapted to be elastically and contracted in the transverse direction B as the innermost sheet member  20 . It should be appreciated that the present invention includes an embodiment according to which both the front edge  21  and the rear edge  22  are not elastically contractible in the transverse direction B. 
       FIG. 5  is a partially cutaway perspective view of one preferred embodiment of the diaper  1  according to the present invention. Regions and members of this embodiment similar to those in the diaper  1  of  FIG. 1  are designated with similar reference numerals. Specifically, the diaper  1  of  FIG. 5  also has the crotch region  6 , the front waist region  7  and the rear waist region  8  wherein the side edges  7   a ,  7   a  and  8   a ,  8   a  of the front and rear waist regions  7 ,  8  are put flat and sealed together at the joints  9  arranged intermittently in the vertical direction to form the waist-opening  11  and a pair of the leg-openings  12 . The diaper  1  according to this embodiment also includes the innermost sheet member  120  facing the wearer&#39;s skin (not shown) and a bodily fluid absorbent member  122  attached to the outer surface  120   b  of the innermost sheet member  120  wherein these innermost sheet member  120  and the bodily fluid absorbent member  122  are integrated with each other to form the pant-shaped chassis  10 . The innermost sheet member  120  is preferably hydrophobic, more preferably hydrophobic and liquid-impervious. Elastic sheet pieces  52  are bonded under tension to the inner surface of the innermost sheet member  120  in the front waist region  7  and the rear waist region  8 , respectively, so that the innermost sheet member  120  may be elastically contracted in the circumferential direction. The innermost sheet member  120  is formed in the crotch region  6  with the front opening  33  and the rear opening  34 . The front opening  33  has the peripheral edge  33   b  and is positioned in front of the transverse center line Q-Q so that the wearer&#39;s external genital can be exposed in this front opening  33 . The rear opening  34  has the peripheral edge  34   b  and is positioned behind the transverse center line Q-Q so that the wearer&#39;s anus can be exposed in this rear opening  34 . Referring to  FIG. 5 , the deformation restricting sheet member  81  interposed between the lower segment  34   b  of the peripheral edge  34   b  and the lower segments  34   c  of the peripheral edge  34   b  both of the innermost sheet member  120  to join these two segments  33   c ,  34   c  is shown (See  FIG. 6  also). The imaginary lines J indicate the potential behavior of the bodily fluid-absorbent structure  122  in the crotch region  6  moving inward in opposite directions of the arrows E and F and thereby being crooked so as to be pressed in a direction of the arrow G against the diaper wearer&#39;s skin. The deformation restricting sheet member  81  is effective to restrict such potential behavior. 
     The bodily fluid absorbent member  122  has the bodily fluid absorbent structure  45  comprising the liquid-pervious inner sheet  2 , the liquid-impervious outer sheet  3  and the bodily fluid absorbent core  4  sandwiched the inner and outer sheets  2 ,  3 . These inner and outer sheets  2 ,  3  extend outward beyond the periphery of the core  4  and put flat and bonded together outside the periphery of the core  4  wherein at least one of these inner and outer sheets  2 ,  3  is bonded to the innermost sheet member  120  so that the front opening  33  and the rear opening  34  may be covered with said one of the inner and outer sheets  2 ,  3  from outside of the innermost sheet member  120 . Along the side edges  13  of the crotch region  6 , the inner sheet  2 , the outer sheet  3  and the innermost sheet member  120  are placed one on another and bonded together. Also along the side edges  13 , the leg elastic members  14   b  sandwiched between the inner sheet  2  and the outer sheet  3  is bonded under tension to at least one of these two sheets  2 ,  3 . Between the side edges  13 , the inner sheet  2  and the innermost sheet member  120  are not bonded to each other so that the innermost sheet member  120  may be spaced from the inner sheet  2  in the thickness direction of the core  4  to form the body waste retaining space  31  into which urine flows through the front opening  3  and feces moves through the rear opening  34 . 
       FIG. 6  is a sectional view taken along the line VI-VI in  FIG. 1  wherein the line VI-VI corresponds to the center line P-P extending in the front-back direction. The innermost sheet member  120  is indirectly bonded to itself along the lower segment  33   c  of the peripheral edge  33   b  defining the front opening  33  and the lower segment  34   c  of the peripheral edge  34   b  defining the rear opening  34  via the deformation restricting sheet member  81  having the thickness N and the height K. The portion  36  of the innermost sheet member  120  defined in the front-back direction A between the lower segments  33   c ,  34   c  sags down toward the lowermost portion  6   a  of the crotch region  6 . The portion  36  of the innermost sheet member  120  extending between the lower segments  33   c ,  34   c  in the front-back direction A extends downward toward the lower most portion  6   a  of the crotch region  6  and the lower end  35  of the innermost sheet member  120  is joined to the inner sheet  2 . 
       FIG. 7  is a view similar to  FIG. 6 , showing another preferred embodiment of the present invention. In the diaper  1  shown by  FIG. 7 , the innermost sheet member  120  is directly bonded to itself to form the separator  20   a . The deformation restricting sheet member  81  is attached to the rear surface  83  of the separator  20   a . With this alternative arrangement, there is possibility that loose passage flowing into the body waste retaining space comes in direct contact with the deformation restricting sheet member  81 . Considering such possibility, it will be advantageous to form the deformation restricting sheet member  81  by a sponge having interconnected cells or a sheet material having many voids such as a nonwoven fabric of crimped conjugate fibers since loose passage can be trapped by these voids. By trapping loose passage of high fluidity in the voids, loose passage would be prevented from flowing out of the rear opening and soiling the wearer&#39;s skin. It should be appreciated here that the deformation restricting sheet member  81  may be attached not to the rear surface  83  but to the front surface  82  of the separator  20   a  without departing from the scope of the present invention.