Patent Abstract:
A disposable absorbent article is provided comprising a liquid absorbent pad having a large single through slit designed to control fluid surge and minimize fluid leakage when fluid is discharged suddenly during the use of the article.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates to a liquid absorbent pad having a single large through slit for use in absorbent articles such as diapers, briefs, incontinence garments, sanitary napkins, and the like articles. The invention also relates to absorbent articles comprising a liquid absorbent pad or layer having a single through slit designed to control the fluid surge in order to prevent or minimize fluid leak when fluid is discharged suddenly during the use of the absorbent article. 
     BACKGROUND OF THE INVENTION 
     It is common knowledge that incontinent persons, many elderly and infants have difficulty controlling urination and often discharge or excrete large amount of urine suddenly, thus causing a fluid surge in the crotch area. Uncontrolled fluid surge results in leakage of fluid unless the absorbent article is especially constructed to contain the fluid surge in order to prevent or minimize fluid leakage. 
     Several different structures have been disclosed for absorbent articles in an effort to control or ameliorate the adverse effects of fluid surge in absorbent articles used by incontinent persons, the elderly and infants. One early patent, i.e., U.S. Pat. No. 3,889,679 issued Jun. 17, 1975 to Glenn N. Taylor, III, describes a disposable diaper which comprises a liquid impervious backing sheet and an absorbent body having a multiplicity of openings therein which extend through said absorbent body thus defining a corresponding multiplicity of fluid passages. The surging fluid flows directly through the absorbent body toward the liquid impervious backing sheet remote from the absorbent body. The passages are cylindrical, have a diameter of from about ¼ to about 1-inch and are provided through the full extent of the absorbent body. 
     In a more recent patent, i.e., U.S. Pat. No. 5,300,053 issued Apr. 5, 1994 to Donald M. Genaro, an absorbent brief is described which comprises a liquid-permeable top layer, a liquid-impervious backing layer and absorbent layer sandwiched between said two layers. The absorbent layer has a dispersion channel which extends through the absorbent layer to the liquid-impervious layer for providing unobstructed liquid flow. As shown in  FIG. 1  of the Genaro patent, liquid flowing through the distribution channel  18  can be channeled to secondary channels  18 ′,  18 ″ which, together with distribution channel  18 , form a generally Y-shaped channel. 
     Others have proposed structures for absorbent articles which rely on increased volume of the absorbent pad to absorb the surging fluid and minimize or prevent fluid leak. However, increased volume of absorbent pad contributes to bulkiness of the article which results in inferior fit around the body of the wearer. 
     It has also been suggested to use an absorbent pad made of a high absorbency material, or use superabsorbent polymers (SAP) in the absorbent pad but these alternatives are costly even if the bulkiness of the article is not increased. Others have incorporated an acquisition layer having a basis weight of 50-100 grams per square meter (GSM) in the structure of the absorbent article in order to reduce the “insult time” but this results in increased cost of the article. 
     There is thus a dire need for an absorbent pad for use in diapers, incontinent briefs and the like articles, which is effective for minimizing or preventing fluid leakage caused by sudden fluid surge in and around the crotch area. 
     It is therefore an object of the present invention to provide a liquid absorbent pad for use in absorbent articles, wherein the absorbent pad has a unique construction designed to accommodate and contain fluid surge caused by sudden urination. 
     It is, another object of this invention to provide a liquid absorbent pad useful in absorbent articles wherein the absorbent pad has a single large through slit for accommodating fluid surge and minimizing fluid leaks from the crotch area of the absorbent article. 
     It is also an object of this invention to provide a disposable absorbent article such as diapers, briefs, incontinence garments, sanitary napkins, and the like articles comprising such liquid absorbent pads. 
     It is a further object of this invention to provide a disposable absorbent article which, due to its unique structure of the absorbent pad, helps maintains the top surface of the article dry after a surge of fluid such as by sudden urination. 
     The foregoing and other objects of the present invention will be more fully comprehended from the following detailed description of the invention with reference to the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     In accordance with this invention, a disposable absorbent article is provided which comprises a liquid absorbent pad (core or layer) which has a large elongated through slit designed to prevent leakage of fluid, usually urine, caused by sudden discharge of copious amount of urine by incontinent persons, the elderly, or by infants when using the article. The disposable absorbent article, e.g., a diaper, comprises a liquid pervious topsheet, a liquid-impervious backsheet which, when breathability is required is vapor pervious, a crotch region and a liquid absorbent pad made of a material comprising fluff and super-absorbent polymer (SAP), disposed between the topsheet and the backsheet. The liquid absorbent layer also comprises a crotch region (pad crotch area) and has a top surface and a bottom surface, and a single large through elongated slit which extends from the top surface to the bottom surface of the absorbent pad. The slit dimensions is preferably from about 0.5 inch to about 1.5 inches wide, and from about 2 to about 10 inches long depending on the size of the diaper, and is located within the pad&#39;s crotch region. 
     The liquid absorbent pad is defined by a pair of opposed longitudinal sides and a pair of opposed lateral sides and the slit is also defined by a pair of opposed longitudinal sides and a pair of opposed lateral sides. The region between the sides of the slit and the sides of the pad define a zone enriched with fluff-SAP mixture such that this region contains more fluff-SAP mixture than the remaining portion of the pad, i.e., the non-enriched zone. This fluff-SAP mixture concentration in the vicinity of, or adjacent the sides of the slit insures more effective liquid absorption. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, wherein like reference numerals are employed to designate like parts wherever possible: 
         FIG. 1  is an exploded view of an absorbent brief including an absorbent layer having a single large through slit formed therein in accordance with one embodiment of the present invention; 
         FIGS. 2 and 3  each shows a top view of an absorbent layer illustrating a different embodiment of the pad of this invention for use in an absorbent brief such as the absorbent brief shown in  FIG. 1 ; 
         FIG. 4  is a stretched plan view of a breathable absorbent brief (diaper) incorporating an absorbent layer having a single large through slit formed therein in accordance with the embodiment shown in  FIG. 1 , wherein both the diaper and the absorbent pad are defined by contoured sides; 
         FIG. 4A  is similar to  FIG. 4  in all respects except that only the diaper is contoured; 
         FIG. 4B  is similar to  FIGS. 4 and 4A  in all respects except that only the absorbent layer is contoured; 
         FIG. 4C  is similar to  FIGS. 4 ,  4 A and  4 B in all respects except that neither the diaper nor the absorbent layer is contoured; 
         FIG. 5  is a sectional view taken along the line  5 — 5  in  FIG. 4 ; 
         FIG. 6  is a sectional view taken along the line  6 — 6  in  FIG. 4 ; and 
         FIG. 7  is a sectional view taken along the line  7 — 7  in FIG.  4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to  FIG. 1  of the drawings, there is shown an absorbent article such as a diaper  100  having a liquid permeable topsheet or layer  101 , a liquid impervious backsheet or layer  103  and an absorbent layer  105  sandwiched between the topsheet  101  and the backsheet  103 . The diaper shown in  FIG. 1  is in an hour-glass shape, though it can be formed in butterfly shape or in other configurations. The topsheet  101  includes a back waist section or panel  101 A and a front waist section or panel  101 B, and the backsheet  103  includes a rear waist section or panel  103 A and a front waist section or panel  103 B. The absorbent layer  105  comprises a single through elongated slit  107  formed therein and extending from the top surface through the bottom surface of said layer. The absorbent layer comprises a back panel  105 A and a front panel  105 B, and may be in a generally rectangular configuration, or it may be T-shaped or in hour-glass shape as the brief itself. Regardless of the shape of the absorbent layer, as will hereinafter be described the size and location of the single through aperture  107  are critical in controlling the fluid surge resulting from sudden discharge of copious amounts of urine which is often experienced by incontinent persons, the elderly and the infants. For maximum fluid surge control and leak prevention, the slit  107  is from about 2 to about 10 inches long and is from about 0.5 to about 1.5 inches wide, and is located entirely within the crotch region  109  which region is between the broken lines x—x and y—y in FIG.  1 . Referring back to  FIG. 1 , the backsheet is provided with tabs  111  for securing the rear and front panels together when folded to form the diaper. Tabs  111  may be adhesive tabs, Velcro®, fasteners or other conventional engagement means. 
     The absorbent layer  105  is made of conventional absorbent material known to those skilled in the art such as wood pulp fiber and various types of wettable hydrophilic and cellulosic fibers, all of which are used in the form of “fluff”. Examples of suitable fibrous materials forming the fluff are described in the aforementioned Taylor patent and in U.S. Pat. No. 5,429,629 issued Jul. 14, 1995 to Margaret G. Latimer et al., the disclosures of which are incorporated herein by reference. It is to be understood that the term “fluff” refers to all those fibrous materials disclosed in said patents. While absorbent pads made of fluff exhibit adequate fluid absorption capacity, improvement in fluid absorption is realized by mixing the fluff with Super Absorbent Polymers (SAP) in which the SAP constitutes from about 3 to about 80 weight percent of the fluff-SAP mixture. It has been found that a more effective fluid surge control may be realized when the fluff-SAP mixture is more concentrated in a fluid surge management zone (Z) which is defined by the broken lines around the absorbent layer  105  as shown in FIG.  1 . By increasing the amount of the fluff-SAP mixture in this zone, greater efficiency is realized in containing the sudden surge of fluid which results from uncontrolled urination by incontinent persons, the elderly or by infants. In a typical institutional or household diaper used by adult incontinent persons, the diaper is usually from about 24 to about 40 inches long and from about 17 to about 35 inches wide, and the absorbent layer is from about 19 to about 35 inches long, from about 14 to about 20 inches wide and is from about 100 to about 400 mils thick. The slit  107  must be located within the crotch region, preferably centrally and is defined by the longitudinal sides  107 A,  107 B and the lateral sides  107 C,  107 D which are generally parallel to the respective longitudinal and lateral sides of the zone Z. It has been found that maximum fluid surge control can be realized when the longitudinal sides of zone Z are spaced from about 1 to about 10 inches relative to the respective longitudinal sides  107 A,  107 B of the slit  107 , and the lateral sides of zone Z are spaced from about 6 to about 30 inches relative to the lateral sides  107 C,  107 D of the slit  107 . It is this zone Z that must be enriched in fluff-SAP content relative to the remaining portion of the absorbent layer. In order to realize the advantages of the present invention, the amount of fluff-SAP mixture enriched zone is from about 1.5 to about 5.0 preferably from about 2.0 to about 3.0 times the amount of the fluff-SAP mixture in the non-enriched zone. Thus, the amount of fluff-SAP mixture in the enriched zone can vary from about 400 to about 1000 gsm, preferably from about 600 to about 800 gsm and the amount of fluff-SAP mixture in the non-enriched zone is from about 100 to about 300 gsm. 
     The Super Absorbent Polymers which are suitable for the purpose of this invention are generally well known in the art and are described in the aforementioned Latimer et al. patent. These include polyacrylamide, polyvinyl alcohol, polyvinyl ether, ethylene, maleic anhydride copolymers, polyacrylates, polyacrylamides, polyvinylpyrrolidone, polyacrylates, isobutylene maleic anhydride copolymers, or mixtures of said polymers and copolymers. Crosslinked polyacrylic acid has been found to be particularly effective absorbent when mixed with fiberized wood (fluff) in an amount between about 3 to about 80 weight percent based on the weight of fluff-SAP mixture. 
       FIG. 4  illustrates a diaper in flat-out (stretched) position such as the diaper shown and described in copending application Ser. No. 09/302,385 filed Apr. 30, 1999 which is assigned to the assignee of the present application, except that the diaper in  FIG. 4  herein includes an absorbent layer or pad having a single through slit in accordance with the present invention. The diaper shown in  FIG. 4  is generally designated as  210  which is defined by the opposed side edges  212  and  214 , the back end edge  216  and front end edge  218  which connect the side edges. Each of the side edges  212  and  214  has a medial cutout portion which defines the leg openings  220  and  222  for insertion of the legs of the wearer therethrough when the back end edge  216  is folded onto the front end edge  218  to form the diaper structure as it is worn by the user. As is further shown in  FIG. 4 , each of the side edges  212  and  214  has laterally extending side ears or panels  224 . The diaper  210  also comprises a breathable backsheet  226 , a fluid pervious front or top sheet  228  facing the body of the wearer and an absorbent pad or layer  230  disposed between the top sheet and the back sheet as shown in  FIGS. 5-7 . The top sheet is generally coextensive with the backsheet although this is not strictly necessary. Also shown in  FIGS. 5 ,  6  and  7 , is an acquisition layer  232  interposed between the top sheet  228  and the absorbent pad  230 . The acquisition layer serves to temporarily retain the body exudates and slowly distribute them through the absorbent pad  330  in order to keep the skin dry and reduce diaper leakage. Referring again to  FIGS. 5-7 , the composite layers also include the layer  234 , generally made of liquid and vapor impermeable polyethylene, which preferably spans the length of the absorbent article and extend laterally toward the sides of the diaper, ending at the cutout portions (leg holes)  220 , 222 . The polyethylene film  234  may be laminated to the backsheet  226  as seen from  FIGS. 5-7  and thus provides an area which is liquid and vapor impervious. As a process aid, a tissue layer may be interposed between the absorbent layer  230  and the backsheet  226 . 
     Referring again to  FIG. 4 , the backsheet  226  is provided with a pair of opposed, perforated (or non-perforated) films or landing zones  236 , usually made of flexible polyolefin plastic such as polyethylene or polypropylene, a polyester, a cellulose ester or some other plastic material known in the art, but preferably it is made of polyethylene or polypropylene. A pair of releasable tabs, e.g., adhesive tabs  238  are provided at the rear side panels or ears  224  such that when the back waist end  216  is folded onto the front waist edge  218  of the diaper, the tabs  238  are securely adhered onto the corresponding surfaces of the landing zones  236 . Thus, each landing zone  236  has an inside surface which is adherent to the backsheet  226 , and an exterior surface which is adapted to be releasably fastened to the tabs  238 . To this end, the exterior surface of each landing zone  236  may be treated with silicone or other suitable material so as to render its surface releasably adherent to the tabs  238 . Instead of using a release agent or in combination therewith, the exterior surfaces of the landing zones may be embossed in order to reduce the adhesion forces between the fastening tabs and the exterior surfaces of these zones. It can be seen therefore that in use, when the back waist panel  216  is folded onto the front waist  218  the releasable tabs  238  can be fastened at any point on the surfaces of the landing zones  236  thus affording adjustment and improved fit of the diaper around the waist of the wearer. Although two perforated landing zones are shown in  FIG. 2 , one or more such zones may be provided which may or may not be perforated, as desired. However, perforated landing zones impart breathability to the diaper. 
     The diaper  210  also comprises at least one or more elastic members or bands  240  disposed near the opposite sides  212  and  214 . Preferably 2 to 4 such elastic bands are used and act as “gatherers” in the crotch region  242 . These elastic members are sometimes referred to in the art as crotch elastics and serve to prevent fluid leakage from the crotch area through the leg openings of the diaper. The elastic bands  240  are usually under tension and are adhesively secured at the sides of the article between the top or cover sheet  228  and the polyethylene backing film  234 . 
     In accordance with this invention, the absorbent pad  230  has a single through elongated slit  244  formed therein which is generally rectangular shaped although it may have some other geometrical shape such as, e.g., oval. In order to realize the advantages of the present invention the slit  244  is disposed within the crotch region  242  of the absorbent pad when the diaper and the absorbent pad have the configurations shown in FIG.  4 . This region is the area defined by the points A, B, C and D which are formed by intersection of the line x—x and y—y and the longitudinal sides of the absorbent pad  230 . Thus, the crotch region of the absorbent pad  230  must be distinguished from the crotch region  243  of the diaper shown in FIG.  4 . It can be appreciated therefore that the crotch region  242 A in  FIG. 4A  is the area defined by the points A′, B′, C′ and D′ formed by intersection of the lines x′—x′ and y′—y′ with the longitudinal sides of the absorbent pad  230 , and this crotch region is to be differentiated from the diaper crotch region  243 A. In  FIG. 4B , the pad crotch region  242 B is the area in the pad defined by the points A′, B′, C′ and D′ formed by the intersection of the lines x″—x″ and y″—y″ with the longitudinal sides of the absorbent pad. Again this region is to be distinguished from the diaper crotch region  243 B. Similarly in  FIG. 4C , the pad crotch region  242 G is the area defined by the points A 2 , B 2 , C 2  and D 2  formed by the intersection of the lines x″—x″ and y″—y″ with the longitudinal sides of the pad  230 , and is to be distinguished from the diaper crotch region  243 C. Finally, in  FIG. 4C  the pad crotch region  242 C is the area in the pad defined by the points A 3 , B 3 , C 3  and D 3  formed by the intersection of the lines x″—″ and y″—y″ with the longitudinal sides of the pad  230 . Once again, the pad crotch region  242 C is to be distinguished from the diaper crotch region  243 C. 
     The advantages of the present invention are best realized when the elongated slit is within the pad crotch region. 
     The slit  240  according to the present invention is from about 2 to about 10 inches long and from about 0.5 to about 1.5 inches wide. In  FIG. 4 , the slit  244  is defined by the longitudinal generally parallel sides  244 A,  244 B and the lateral generally parallel sides  244 C,  244 D, and is cut through the entire thickness of the absorbent pad which is usually about 100 to about 400 mils thick. It must be mentioned that the preferred location of the slit  244  depends on the expected wearers of the diaper. Thus, when the diaper is to be used by incontinent elderly men, or by infants, the slit is located at the middle of the pad crotch region, whereas in diapers expected to be worn by incontinent females, the slit is off the center of the pad crotch region, closer to the back edge of the absorbent pad, but still entirely within the pad crotch region.  FIGS. 2 and 3  illustrate absorbent pads in which the slits are formed slightly off from the middle of the pad crotch region. In  FIG. 3 , the absorbent pad is shown as a butterfly shape pad. However, the shape of the pad does not reduce the efficacy of fluid surge management of the absorbent pad. 
     The superior surge management control efficacy of an absorbent pad having a single through slit of 5 inches long and 1 inch according to the present invention was compared to an absorbent pad without an aperture. The structure and construction of the pads were otherwise similar and each pad was incorporated in a similar size diaper. The tests were designed to determine the “insult” rate, i.e., the rate of penetration of fluid into the absorbent core. Leakage from the crotch region of the diaper is less when urine penetrates faster into the absorbent core. Thus, the shorter this time, the lower is the insult rate and the less the fluid leakage from the diaper. The test procedure and equipment used are described below. 
     
       
         
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
           
               
                   
               
             
             
               
                 1. 
                 Scope and Purpose: 
               
             
          
           
               
                   
                 1.1 
                 To measure the ability of an incontinence product to accept 
               
               
                   
                   
                 and retain synthetic urine under simulated in-use conditions of 
               
               
                   
                   
                 load and pressure. 
               
               
                   
                 1.2 
                 To calculate amount of time required for an absorbent article 
               
               
                   
                   
                 to absorb a fixed quantity of a test solution and to measure the 
               
               
                   
                   
                 dryness of the product. 
               
             
          
           
               
                 2. 
                 Definitions: 
               
             
          
           
               
                   
                 2.1 
                 Rewet or dryness: amount of wetness returned to the surface 
               
               
                   
                   
                 of an incontinent product onto an absorbent filter paper. 
               
             
          
           
               
                 3. 
                 Reagents: 
               
             
          
           
               
                   
                 3.1 
                 0.9% Sodium Chloride (NcCl) Solution 
               
               
                   
                 3.2 
                 0.01% Fuchsin Acid (Optional)-dye used for coloring Sodium 
               
               
                   
                   
                 Chloride solution. 
               
             
          
           
               
                 4. 
                 Equipment: 
               
             
          
           
               
                   
                 4.1 
                 125 ml separatory funnel, discharging 7 ml/sec 
               
               
                   
                 4.2 
                 NIST Traceable Timer 
               
               
                   
                 4.3 
                 Weights 
               
             
          
           
               
                   
                 4.3.1 
                 Stainless steel cylindrical weight 9.8 lbs.: 9.0 cm 
               
               
                   
                   
                 diameter 1.0 psi 
               
             
          
           
               
                   
                 4.4 
                 Dosing Rings 
               
             
          
           
               
                   
                 4.4.1 
                 Stainless steel ring (60 mm ID, 70 mm OD, 40 
               
               
                   
                   
                 mm Height) 300 
               
             
          
           
               
                   
                 4.5 
                 Filter paper: AFI Grade 950, 9.0 cm diameter or equivalent 
               
               
                   
                   
                 filter paper 
               
               
                   
                 4.6 
                 Ringstand with Support Ring 
               
               
                   
                 4.7 
                 100 ml volume graduated cylinder 
               
               
                   
                 4.8 
                 10 ml volume graduated cylinder 
               
               
                   
                 4.9 
                 Analytical Balance able to weight to nearest 0.01 grams. 
               
             
          
           
               
                 5. 
                 Procedure: 
               
             
          
           
               
                   
                 5.1.1 
                 Trim the leg gathers, if present, out of the product so the 
               
               
                   
                   
                 product may lay flat. 
               
               
                   
                 5.1.2 
                 Fold under the front and back wing flaps, leaving product 
               
               
                   
                   
                 target area flat and in contact with test surface area. 
               
               
                   
                 5.1.3 
                 TEST PROCEDURE: 
               
             
          
           
               
                   
                 5.1.3.1 
                 Measure out volume of test solution with 
               
               
                   
                   
                 graduated cylinder and transfer the solution to the 
               
               
                   
                   
                 separatory funnel. If using the ring stand make 
               
               
                   
                   
                 sure the funnel is secured on the stand and proper- 
               
               
                   
                   
                 ly suspended from the support ring. 
               
             
          
           
               
                   
                 5.1.3.1.1 
                 Volume 100 ml test solution for Briefs, 
               
               
                   
                   
                 2-Piece, Protective Underwear, and 
               
               
                   
                   
                 Belted Garments. 
               
             
          
           
               
                   
                 5.1.3.2 
                 Center the dosing ring over the target zone, 
               
               
                   
                   
                 centrally located with tip of funnel approximately 
               
               
                   
                   
                 40 mm from the sample surface (same height as 
               
               
                   
                   
                 top of dosing ring). 
               
             
          
           
               
                   
                 5.1.3.2.1 
                 The target zone for briefs and 2-piece 
               
               
                   
                   
                 undergarments is at the center of the 
               
               
                   
                   
                 crotch area. 
               
               
                   
                 5.1.3.2.2 
                 The target zone for protective under- 
               
               
                   
                   
                 wear is the center of the narrowest 
               
               
                   
                   
                 crotch width of the pad. 
               
             
          
           
               
                   
                 5.1.3.3 
                 Deliver the test solution into the ring by fully 
               
               
                   
                   
                 opening the stopcock on the funnel. At the same 
               
               
                   
                   
                 time, start the timer to record speed in seconds for 
               
               
                   
                   
                 the test solution to completely enter the product. 
               
               
                   
                   
                 Stop the timer when all solution has passed 
               
               
                   
                   
                 through the top sheet and record the time. This is 
               
               
                   
                   
                 the Acquisition Speed. 
               
               
                   
                 5.1.3.4 
                 Wait fifteen (15) minutes +/− 1 minute using 
               
               
                   
                   
                 timer. 
               
               
                   
                 5.1.3.5 
                 Place a stack of pre-weighed filter papers (10-15 
               
               
                   
                   
                 filter papers, W1) on the center of the wetted 
               
               
                   
                   
                 target area. 
               
               
                   
                 5.1.3.6 
                 Place a 1.0 psi cylindrical weight (9.0 cm, 9.8 lb. 
               
               
                   
                   
                 Equals 1.0 psi) on the top of the dry filter paper, 
               
               
                   
                   
                 making sure the stack is level, not tipping to one 
               
               
                   
                   
                 side or the other. Start the timer. 
               
               
                   
                 5.1.3.7 
                 After one (1) minute, remove the cylindrical 
               
               
                   
                   
                 weight and the wetted out papers. 
               
               
                   
                 5.1.3.8 
                 Reweigh the filter paper stack (W2) and record 
               
               
                   
                   
                 the wet filter paper weight. 
               
               
                   
                 5.1.3.9 
                 Note: if the entire stack of filter paper is wetted, 
               
               
                   
                   
                 the test is invalid and must be reevaluated with a 
               
               
                   
                   
                 new sample of using a heavier (5.0 g additional) 
               
               
                   
                   
                 stack of dry filter paper. 
               
             
          
           
               
                   
                 5.1.4 
                 MULTIPLE DOSE REWETS 
               
             
          
           
               
                   
                 5.1.4.1 
                 Repeat sections 5.1.3.1 through 5.1.3.9 up to two 
               
               
                   
                   
                 (2) more times on the same product. 
               
             
          
           
               
                   
                 5.4 
                 CALCULATIONS 
               
             
          
           
               
                   
                 5.4.1. 
                 REWET (g) = W2 (Wet filter paper weight) − W1 
               
               
                   
                   
                 (Dry Filter paper weight) 
               
               
                   
                   
               
             
          
         
       
     
     The test results are shown in Table 1 below, using two similar diapers except that one was without a slit and the other with a 1.5 slit. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Control diaper 
                 Diaper with slit as 
               
               
                   
                 without slit 
                 in FIG. 3 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Overall Product Wt. 
                 130.96/11.9 
                 130.11/1.7 
               
               
                 Gm Dryness, gm 
               
               
                 1 
                 0.04 
                 0.04 
               
               
                 2 
                 2.38 
                 0.61 
               
               
                 3 
                 11.70 
                 5.92 
               
               
                 Insult Time, Sec. 
               
               
                 1 
                 11.70 
                 10.9 
               
               
                 2 
                 48.4 
                 11.1 
               
               
                 3 
                 32.7 
                 12.1 
               
               
                   
               
             
          
         
       
     
     As shown in the above table, the insult time for a diaper comprising an absorbent core having a through single slit of 1 inch×5 inches is considerably lower as compared to the diaper which includes an absorbent core without an aperture. It is also noted that the dryness is remarkably lower when using an absorbent pad according to the present invention. 
     Additional tests were conducted to determine the effect that slit size in the pad (length) on the insult time, in seconds. The test procedure was essentially the same as hereinbefore using similar diapers; one for control (without a slit) and others have 1 inch wide slit but slit lengths of 10 inches, 7 inches and 4 inches, respectively. The results are shown in Table 2 below. 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Sample No. 
                 Control 
                 10 inch slit 
                 7 inch slit 
                 4 inch slit 
               
               
                   
               
             
             
               
                 1 
                 21 
                 19 
                 17 
                 16 
               
               
                 2 
                 35 
                 18 
                 18 
                 17 
               
               
                 3 
                 50 
                 25 
                 23 
                 32 
               
               
                   
               
             
          
         
       
     
     The diaper with 10 inch and 7 inch slit exhibited liquid run offs on the second and third runs. Liquid was observed coming up through the slit in the absorbent pad from outside of the dosing ring. 
     In making the absorbent article of the present invention, the top or cover sheet  228  conveniently made of spunbond nonwoven polypropylene which is available from First Quality Fibers, Inc., McElhattan, Pa. The acquisition layer  232  is usually made of chemically or thermally bonded nonwoven polyester polypropylene fibers available from, BBA Nonwovens, Simpsonville, N.C. Preferably the width of the acquisition layer  332  is 3 to 5 inches wide. The abosorbent pad  230  may be made of mixture wood pulp fibers (fluff) and superabsorbent polymers such as IM 7000 series available from Clariant Products, Inc., Portsmouth, Va., and Chemdal 200 Series, available from Chemdal, Inc., Palatin, Ill. Alternatively, the absorbent pad  230  may be of dual construction, in which case the absorbent polymer may be securely positioned between layers of the absorbent material. 
     The backing layer  234  may be a polyethylene backing film and is generally non-porous and is liquid, air and vapor impermeable. This layer is placed under the absorbent layer  230  in order to prevent the body exudates from leaking and thus soiling the user&#39;s bed and clothing. This film usually covers at least the area under the absorbent pad  230 . In a preferred construction, the backing film  234  is adhesively or thermally laminated to the nonwoven backsheet  226 , which itself is made of spunbond nonwoven polypropylene available from First Quality Fibers, McElhattan, Pa. Polyethylene suitable as backing film for making the diapers of this invention are available from Clopay Plastics, Cincinnati, Ohio. Alternatively, a layer of hydrophilic tissue may be used made of cellulosic fibers bonded together thermally, chemically or by the use of suitable sizing agents placed between the absorbent pad and the backing film. For improved effectiveness, the hydrophobic tissue may be laminated (cold or hot) to the nonwoven backsheet. 
     While the use of the absorbent pad of this invention has been described in connection with a breathable diaper, it must be understood that such description is for the purpose of illustration and is not intended to be a limitation on the use of this pad. Other types of diapers and briefs, and other absorbent articles such as sanitary napkins or pull ups may incorporate these pads in order to improve their liquid absorption. 
     Also, the backsheet used in the absorbent articles contemplated by the present invention may be a single film which is liquid-impermeable but vapor permeable or it may be a composite sheet made of a liquid-impermeable and vapor permeable film adherent to a layer of nonwoven material. The term “backsheet” as used herein is intended to encompass all such films and composites. Other changes and modifications may be made which are obvious from the foregoing detailed description.

Technology Classification (CPC): 0