Abstract:
A disposable diaper is provided on the inner surface of a crotch region with a pair of barrier cuffs opposed to each other about a longitudinal center line. Each of the barrier cuffs includes inner and outer sheet strips in the form of sheet strips provided separately of each other. The first and second sheet strips include bottom side edges fixed to the inner surface of the diaper and top side edges left free from the inner surface in the crotch region. The bottom side edge of the first sheet strip is spaced aside from the bottom side edge of the second sheet strip toward the center line. The first and second sheet strips are collapsed onto the inner surface of the diaper and overlap to each other in such collapsed state. The first and second sheet strips are locally bonded to each other in a part of the overlapping area of these sheet strips. One of the first and second sheet strips has its top side edge placed aside from the top side edge of the other sheet strip toward the center line and provided with an elastic member.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a disposable diaper including a pair of elasticized barrier cuffs.  
         [0002]     Disposable diapers including a pair of barrier cuffs elastically biased to be raised from the inner surface of the diaper have conventionally been well known. Specifically, such cuffs are raised from the inner surface of the diaper as elastic members attached in a stretched state to the diaper contract. Rising up in this manner, the cuffs function to prevent body fluid discharged on the inner surface of the diaper from leaking sideways.  
         [0003]     For example, a disposable diaper disclosed in Japanese Unexamined Patent Application Publication No. 1989-162807 (REFERENCE 1) is provided in a crotch region with a pair of floating inner cuffs extending in a longitudinal direction. Each of these floating inner cuffs comprises a cuff layer defined by a part of topsheet, a base layer underlying the cuff layer and an elastic member sandwiched between the cuff layer and the base layer so as to extend in the longitudinal direction in a contractible manner. The elastic member is partially bonded to the base layer and the segment of the elastic member left free from the base layer functions to lift the cuff layer off from the base layer as this segment contracts. The cuff layer is bonded in its region a predetermined dimension spaced from the elastic member in a transverse direction of the diaper to the base layer. When lifted in this manner, the cuff layer describes an inverted V-shaped cross-section and thereby forms a double wall barrier cuff comprising walls lying inwardly and outwardly as viewed in a transverse direction of the diaper.  
         [0004]     A disposable diaper disclosed in Japanese Unexamined Patent Application Publication No. 1989-213402 (REFERENCE 2) comprises a first sheet including side flaps put in close contact with the wearer&#39;s skin and a second sheet underlying the first sheet wherein each of the side flaps is provided in the vicinity of its outer side edge with a first elastic member and between the first elastic member and a liquid-absorbent core with a second elastic member. The first sheet is bonded in its two regions spaced from the second elastic member in opposite directions to the second sheet so that the first sheet may protuberate between these two regions as the second elastic member contracts. Consequentially, the first sheet forms a double wall barrier cuff comprising walls lying inwardly and outwardly as viewed in the transverse direction of the diaper.  
         [0005]     The elasticized double wall barrier cuffs disclosed in REFERENCES 1 and 2 are respectively constructed in the manner that the elastic members are sandwiched between two sheets defining the inner walls and the outer walls as viewed in the transverse direction of the diaper, respectively, on transversely opposite lateral zones of the diaper so that these elastic members may lift the inner walls from below. According to such construction, a height of these barrier cuffs depends on the transversely opposite lateral zones of the diaper. It is desired to increase a height of the barrier cuffs, the transversely opposite lateral zones, particularly in the crotch region must be widened. However, any intention to widen a dimension of the crotch region is constrained by the essential condition for design. In order to increase a height of the barrier cuffs with the knowledge of such constraint, a width dimension of the body fluid absorbent core laid in the crotch region should be inevitably reduced. With the diaper having such narrow core, a capacity of the body fluid absorption in the crotch region is generally deteriorated. Therefore, it is an object of the present invention to solve the problem left behind unsolved by the prior art concerning the double wall barrier cuffs.  
       SUMMARY OF THE INVENTION  
       [0006]     According to the present invention, there is a disposable diaper having a front waist region, a rear waist region and a crotch region. The disposable diaper comprises an inner surface put in contact with the wearer&#39;s skin and an outer surface put in contact with an undergarment and a body fluid absorbent core interposed between the inner and outer surfaces. The disposable diaper is formed on its inner surface with a pair of elastic barrier cuffs opposed to each other about a center line bisecting a width dimension of the crotch region so as to extend into the front and rear waist regions and adapted to be raised from the inner surface.  
         [0007]     The present invention further comprises each of the barrier cuffs comprising inner and outer sheet strips in a form of sheet strips provided separately of each other, these first and second sheet strips respectively comprise bottom side edges fixed to the inner surface in the front and rear waist regions as well as in the crotch region and top side edges left free from the inner surface at least in the crotch region of the front waist region, the rear waist region and the crotch region. The bottom side edge of the first sheet strip is spaced aside from the bottom side edge of the second sheet strip toward the center line, the first and second sheet strips are collapsed onto the inner surface and overlap to each other in such collapsed state, and the first and second sheet strips are locally bonded in sections thereof extending in parallel to the center line to each other and one of these first and second sheet strips has its top side edge placed aside from the top side edge of the other sheet strip toward the center line while the top side edge of the other sheet strip is provided with an elastic member extending in parallel to the center line and bonded in a stretched state thereto.  
         [0008]     According to other embodiment of the present invention, the top side edge of the one of said first and second sheet strips is also provided with an elastic member extending in parallel to the center line and bonded in a stretched state thereto.  
         [0009]     According to another embodiment of the present invention, an intermediate section of the first sheet strip defined between a section over which the first sheet strip and the second sheet strip are bonded to each other and the bottom side edge of the first sheet strip is provided with an elastic member extending in parallel to the center line and bonded in stretched state thereto.  
         [0010]     In the disposable diaper according to the present invention, each of the barrier cuffs comprises the first sheet strip and second sheet strip provided separately of the first sheet strip wherein the bottom side edge of the first sheet strip is spaced aside from the bottom side edge of the second sheet strip toward the center line. Such unique arrangement allows a height dimension of the barrier cuff to be increased by increasing a width dimension of at least one of the first and second sheet strips. The first and second sheet strips cooperate with the inner surface of the diaper to define a space and thereby to provide the double wall barrier cuff of which the second sheet strip functions as means to conceal contamination of the first sheet strip with body fluid.  
         [0011]     According to the embodiment of the present invention wherein the first and second sheet strips are respectively provided along the top side edges thereof with the elastic members bonded in a stretched state thereto, the barrier cuff is more effectively raised up from the inner surface of the diaper than when only one of the first and second sheet strips is provided along its top side edge with the elastic member bonded in stretched state thereto. Consequentially, the respective top side edges can be elastically put in close contact with the wearer&#39;s skin.  
         [0012]     According to the embodiment of the present invention wherein an intermediate section of the first sheet strip defined between a line along which the first sheet strip and the second sheet strip are bonded to each other and the bottom side edge of the first sheet strip is provided with the elastic member extending in parallel to the center line and bonded in stretched state thereto, the first sheet strip is formed with gathers in the vicinity of its intermediate section including this elastic member. These gathers function to prevent the first and second sheet strips from coming unacceptably close to each other and thereby to maintain the sufficiently large space between the first and second sheet strips. 
     
    
     BRIEF DESCTIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a partially cutaway plan view showing a disposable diaper according to the present invention;  
         [0014]      FIG. 2  is a plan view showing a part of  FIG. 1  in an enlarged scale;  
         [0015]      FIG. 3  is a sectional view taken along the line III-III in  FIG. 1 ;  
         [0016]      FIG. 4  is a view similar to  FIG. 3 , showing a posture taken by one of barrier cuffs when the disposable diaper bows;  
         [0017]      FIG. 5  is a view similar to  FIG. 1 , showing other embodiment of the present invention;  
         [0018]      FIG. 6  is a sectional view taken along the line VI-VI in  FIG. 5 ; and  
         [0019]      FIG. 7  is a view similar to  FIG. 4 , showing a posture taken by one of barrier cuffs when the disposable diaper of  FIG. 5  bows. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Details of a disposable diaper according to the present invention will be more fully understood from the description given hereunder with reference to the accompanying drawings.  
         [0021]      FIG. 1  is a partially cutaway plan view showing a disposable diaper  1  and  FIG. 2  is a plan view showing a circled part II of  FIG. 1  in an enlarged scale. The diaper  1  comprises a liquid-pervious topsheet  2  defining an inner surface put in contact with the wearer&#39;s skin, a liquid-impervious backsheet  3  defining an outer surface put in contact with clothes and a body fluid absorbent core  4  sandwiched between these two sheets  2 ,  3 . The diaper  1  has a longitudinal direction L and a transverse direction W, defining a front waist region  6 , a rear waist region  7  and a crotch region  8  extending between these two waist regions  6 ,  7  in the back-and-front direction L. The front and rear waist regions  6 ,  7  are respectively provided along respective ends  11 ,  12  thereof with waist elastic members  13 ,  14  sandwiched between the top- and backsheets  2 ,  3  and bonded in a stretched state to at least one of these sheets  2 ,  3 . The crotch region  8  is provided along its transversely opposite side edges  16  with leg elastic members  17  sandwiched between the topsheet  2  and the backsheet  3  and bonded in a stretched state to at least one of these sheets  2 ,  3 . The rear waist region  7  is provided on its transversely opposite side edges  18  with tape fasteners  19  used to connect the front and rear waist regions  6 ,  7  with each other. Paired barrier cuff  20  is laid on the inner surface of the diaper  1  on both sides of a center line C-C bisecting a width of the diaper  1 , respectively.  
         [0022]     Each of the barrier cuffs  20  comprises inner and outer sheets  21 ,  22  provided separately of each other placed upon each other and extending in the longitudinal direction L as seen in  FIG. 1 . The inner sheet  21  is of preferably liquid-impervious nature and bonded along front and rear ends  26 ,  27  and an outer side edge  28  thereof to the topsheet  2  by means of hot melt adhesive  24 . An inner side edge  29  as well as an intermediate section  31  extending between the inner side edge  29  and the outer side edge  28  is not bonded to the topsheet  2  and an elastic member  32  exclusively for the intermediate section  31  extending in the longitudinal direction L is attached in a stretched state to the intermediate section  31  by means of hot melt adhesive (not shown). The outer sheet  22  also is preferably of liquid-impervious nature and bonded along front and rear ends  36 ,  37  and an outer side edge  38  thereof to the topsheet  2  and/or the inner sheet  21  overlapping the outer sheet  22  by means of hot melt adhesive  34 . While the inner side edge  39  of the outer sheet  22  is bonded neither to the topsheet  2  nor to the inner sheet  21 , an intermediate section  41  extending between the inner side edge  39  and the outer side edge  38  is bonded to the inner side edge  29  of the inner sheet  21  by means of hot melt adhesive  43 . An elastic member  42  exclusively for the inner side edge  39  is attached in a stretched state to the inner side edge  39  by means of hot melt adhesive (not shown).  
         [0023]      FIG. 3  is a sectional view taken along the line III-III in  FIG. 1 . For better understanding of the cross-sectional shape in question, the barrier cuff  20  is shown to be slightly raised from the topsheet  2  with the outer sheet  22  being slightly spaced from the inner sheet  21 . The outer side edge  28  of the inner sheet  21  fixed to the topsheet  2  by means of adhesive  24  is placed aside toward the center line C (See  FIG. 1 ) with respect to the outer side edge  38  of the outer sheet  22  fixed to the topsheet  2  by means of adhesive  34 . The inner side edge  29  of the inner sheet  21  is bonded to the intermediate section  41  of the outer sheet  22  and the inner side edge  39  of the outer sheet  22  extends inward beyond the inner side edge  29  of the inner sheet  21  toward the center line C. Such barrier cuff  20  forms a space  51  surrounded by the inner sheet  21 , the outer sheet  22  and the topsheet  2 . As shown, the topsheet  2  and the backsheet  3  are bonded to the core  4  by means of hot melt adhesive  52 ,  53 , respectively, and portions of these sheets  2 ,  3  extending outward beyond peripheral edge of the core  4  are bonded to each other by means of hot melt adhesive  54 .  
         [0024]      FIG. 4  is a view similar to  FIG. 3 , showing a posture taken by one of the barrier cuffs  20  when the disposable diaper  1  of  FIG. 1  bows in the longitudinal direction with the topsheet  2  inside. The barrier cuff  20  comes into the state substantially as shown when the diaper  1  is put on the wearer&#39;s body. Both the elastic member  42  exclusively for the inner side edge and the elastic member  32  exclusively for the intermediate section contract as the diaper  1  bows. In response to contraction of these elastic members  42 ,  32 , the barrier cuff  20  is fully raised up from the topsheet  2  to maximize the space  51  as shown. In this state, the inner sheet  21  and the outer sheet  22  cooperate with each other to form the double wall structure. With the barrier cuff  20  fully raised up in this manner, the outer side edge  28  of the inner sheet  21  cooperates with the outer side edge  38  of the outer sheet  22  to define a bottom side edge, the inner side edge  39  of the outer sheet  22  defines a top side edge, and the inner side edge  29  of the inner sheet  21  defines a joint to the outer sheet  22 . The barrier cuff  20  taking such posture effectively banks up body fluid flowing outward in the transverse direction of the diaper  1 . Even if the inner sheet  21  is soiled with body fluid, the outer sheet  22  functions to conceal such soil from being highly visible. In addition, even if body fluid permeate the inner sheet  21 , it is unlikely that such body fluid might leak out from the diaper  1  since such body fluid is reliably held by the outer sheet  22  within the space  51 . With the diaper  1  put on the wearer&#39;s body, the inner sheet  21  and the outer sheet  22  always move integrally with each other and therefore it is unlikely that the space  51  might disappear. Consequentially, the outer sheet  22  can reliably conceal soil and, at the same time, prevent leakage of body fluid. The elastic member  42  exclusively for the inner side edge causes the inner side edge  39  of the outer sheet  22  to be shrunk and thereby to be formed with gathers (not shown). The elastic member  32  exclusively for the intermediate section causes the intermediate section  31  of the inner sheet  21  to be shrunk and thereby to be formed with gathers (not shown). These gathers function to prevent the inner and outer sheets  21 ,  22  from coming in close contact with each other when these sheets  21 ,  22  move closer to each other. The contamination concealing effect provided by the outer sheet  22  is ensured so far as these two sheets  21 ,  22  are kept to be spaced from each other. A height of such barrier cuff  20  can be easily increased by expanding a width dimension of the outer sheet  22 . With the diaper  1  put on the wearer&#39;s body, a dimension m by which the inner sheet  21  and the outer sheet  22  are spaced from each other on the topsheet  2  is preferably in a range of 3 to 30 mm and a dimension n by which the barrier cuff  20  is raised up from the topsheet  2 , i.e., a height from the topsheet  2  to the inner side edge  39  of the outer sheet  22  in  FIG. 4  is preferably in a range of 10 to 100 mm.  
         [0025]      FIGS. 5, 6  and  7  show other embodiment of the present invention, of which  FIG. 5  is a view similar to  FIG. 1 ,  FIG. 6  is a sectional view taken along the line VI-VI in  FIG. 5  and  FIG. 7  is a view similar to  FIG. 4 , showing a posture taken by one of the barrier cuffs  20  when the disposable diaper  1  of  FIG. 5  bows. As will be apparent from  FIGS. 5 and 6 , the inner sheet  21  of the barrier cuff  20  has its inner side edge  29  extends toward the center line C beyond the inner side edge  39  of the outer sheet  22  in the rear waist region  7  and the crotch region  8 . It should be noted here that the inner sheet  21  extends obliquely with respect to the center line C as will be apparent from  FIG. 5  so that a dimension by which the opposite inner side edges  29 ,  29  are spaced from each other may be maximized in a urination zone extending from the crotch region into the front waist region. The inner and outer sheets  21 ,  22  are bonded to each other in the respective intermediate sections  31 ,  41  by means of hot melt adhesive  57  while a second elastic member  56  exclusively for the inner side edge  29  is attached in a stretched state to the inner side edge  29  of the inner sheet  21 . It should be noted here that the inner sheet  21  according to this embodiment is not provided with the elastic member  32  exclusively for the intermediate section  31  as seen in  FIG. 3 . The inner side edge  39  of the outer sheet  22  is provided with the elastic member  42  exclusively for the inner side edge  39  similar to that as seen in  FIG. 3 .  
         [0026]     The first mentioned elastic member  42  exclusively for the inner side edge  39  as well as the second elastic member  56  exclusively for the inner side edge  29  contracts so as to raise up the barrier cuffs  20  as shown in  FIG. 6  when the diaper  1  bows. Consequently, the respective inner side edges  29 ,  39  come in close contact with the wearer&#39;s skin under the effect of these elastic members  42 ,  56 . As has previously been described, the dimension by which the inner side edges  29 ,  29  of the respective inner sheets  21 ,  21  is maximized in the urination zone (See  FIG. 5 ) so that urine discharged from the wearer can be reliably absorbed by the core  4  between the barrier cuffs  20 . In this regard, it is possible without departing from the scope of the present invention to adopt, in the diaper  1  of  FIG. 5 , a pair of barrier cuffs arranged in a manner that the inner side edges  29 ,  29  extend not obliquely with respect to the center line C but in parallel to each other.  
         [0027]     The diaper  1  of such construction may be exploited using stock materials as will be described. The liquid-pervious topsheet  2  may be formed from a stock material selected from the group including a nonwoven fabric and a perforated plastic film. The liquid-impervious backsheet  3  may be formed from a stock material selected from the group including a plastic film, a nonwoven fabric and a composite sheet comprising a plastic film and a nonwoven fabric laminated together. The core  4  may be formed from a stock material fluff pulp fibers or a mixture of fluff pulp fibers and super-absorbent polymer particles, in any case, wrapped with a sheet having a high liquid-permeability such as a tissue paper or a nonwoven fabric or a sheet having a high liquid-permeability as well as a high liquid-spreadability. The inner sheet  21  as well as the outer sheet  22  constituting the barrier cuff  20  may be formed from a water-repellent, preferably water-repellent and liquid-impervious sheet in the form of nonwoven fabric or plastic film. In the case of one embodiment wherein sheet material having an air-permeability higher than that of the inner sheet  21  is used as the outer sheet  22 , it is also possible without departing from the scope of the present invention to use the inner and outer sheets  21 ,  22  which are different from each other in terms of an air-permeability, a flexibility and the other properties. Furthermore, it is possible without departing from the scope of the present invention to weld the sheets together instead of bonding them by means of adhesive or vice versa. It is also possible to exploit the present invention not only in the form of the open-type diaper as illustrated but also in the form of the pants-type or pull-on diaper.  
         [0028]     The present invention allows it possible to make the disposable diaper wherein a height of the double wall barrier cuffs can be easily increased.  
         [0029]     The entire discloses of Japanese Patent Application No. 2005-322567 filed on Nov. 7, 2005 including specification, drawings and abstract are herein incorporated by reference in its entirety.